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Dave Elledge sent me populated boards and told me I had to build these out and listen to them. I've learned from experience if Dave says to listen to something then there is something special going on. I've learned a lot form Dave and one of those things is to trust him when he likes something.
I built a pair of amps as mono-blocks a few years ago using these same chips and the results were exceptional. I like the off the grid systems for the zero noise floor and for the fact that they will sound the same no matter where I take them (Audio shows...). Here is a link to that thread: http://www.audiocircle.com/index.php?topic=124981.msg1317309#msg1317309
I think that the Folsom version takes them up several levels by design of the boards much better and with support of assembly. It will be interesting to compare this version to the pair that I made. The power supply is really nice, but I have an expensive power cables on it, plus a balanced power supply from Dodd Audio, and an Uber Buss from Dave Elledge. So three of four thousand dollars worth of conditioning verse a $200 100 amp hour Power Sonic battery. Which will I like better? I don't know.
I mounted the amp part in an Aluminum chassis that Gary Dodd designed before he passed away. I have a lot of them.
(http://gr-research.com/amps/folsom3.jpg)
Somewhere I have a box of on/off switches that fit the front baffle of the chassis. The on/off switch lights up when turned on too. At some point I'll find them and replace what I used with what belongs there.
I used a Neutrik connector for the DC power in. I used Caradas RCA inputs, and tube connectors of coarse. There was no way I'd ruin it with binding posts. :green: The input wire is Vampire's continuous caste Copper. The input coupling caps are Sonicap Platinum's. The speaker wire is our internal wire that is solid core Copper in polyethylene. The power wire is OFC Copper in 12 gauge.
(http://gr-research.com/amps/folsom4.jpg)
I have interconnects from High Fidelity Cables. http://www.highfidelitycables.com/ It's there entry level $1,600 a meter pair version. And the speaker cables are from Electra Cable, B6 model. http://www.electracable.com/speakercables.htm I made the DC cable using a braided 6 wire configuration of Silver Coated Copper.
(http://gr-research.com/amps/folsom8.jpg)
I put the power supply in a separate chassis.
(http://gr-research.com/amps/folsom7.jpg)
I put the power input on one side and the DC output on the other side. And I put a power switch on the input side.
(http://gr-research.com/amps/folsom6.jpg)
Dave populated the boards before sending them to me and there is no telling what extra's he did to them.
(http://gr-research.com/amps/folsom5.jpg)
I turned them on a little bit ago and they are up and playing with no issues. They sound great immediately. Now to let them burn in for a while. Those Sonicap Platinum's are going to take a while....
So more on this after some play time.
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Danny, glad to see your positive review of the Folsom amp. I have built several of them, and I am really impressed with Jeremy's creation. Paired with my X-LS Encores, it's one sweet system for cheap! Hope to hear your observations when the caps break in.
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I have mine (thank you Danny for recommending it to me) hooked up to a pair of X-LS as well and I am stunned at how good the combination sounds. I am really looking forward to trying it with the wedgies (...ahem, Danny).
I believe that Jeremy has come out with another amp with a lot more power. Going to build that one and compare it to the Folsom.
Paul
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I am really looking forward to trying it with the wedgies (...ahem, Danny).
We are working on it.
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Looks very nice! Anybody ever take some measurents on these? Do they produce enough power to drive speakers to fill a good sized room?
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It depends on the efficiency of the speakers.
The amp can actually do 24w peaks, even though it's rated at 15w.
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What exactly is this amp?
Its J-fet or chip amp?
It can be biased in Class A?
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Looks very nice! Anybody ever take some measurents on these? Do they produce enough power to drive speakers to fill a good sized room?
Although if they're that cheap, you could bi-amp or tri-amp.
Do they have a version with turn on based on a trigger (from receiver, for instance)?
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It's AB.
Technically it's a chipamp, but it doesn't sound like any basic chipamp you've heard before (3875, 3886, 7293 etc). It has balanced outputs, which is unlike all of those.
My newer amp uses the 7293 to get some more serious power, but it doesn't sound like the 7293 because it has specialized feedback that is error correcting. It's sensitive enough to compare the incoming and outgoing signal, for voltage tracking, but not when it's own self power is moving. That's why it is battery/solar powered feedback.
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Although if they're that cheap, you could bi-amp or tri-amp.
Do they have a version with turn on based on a trigger (from receiver, for instance)?
I have not made one. The idle current is so low that it isn't really necessary.
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Nice, thanks bro.
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I really like the two chassis design. You could build a battery supply and switch between the two.
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SClark runs 24v battery power on his unit. It can be done fairly easy. I'm not saying it's better or anything, as I usually prefer AC powered gear, but it works well with the design of the amplifier and keeps the voltage regulation section active - which is also a major filter.
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Does the new amp have the capability for balanced inputs?
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Not yet. It requires a lot more work due to the way the feedback works. Maybe I'll have a solution for a possibility with an additional PCB board you'd need to run along with it, but I don't suspect the demand for that too soon.
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Thanks for the feedback.
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Looks like a fun project. If only there was a kit available.
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What would a kit need to entail for you? When someone orders I include an uploadable BOM to mouser for all the parts that go on the PCB boards, and the transformer.
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I really like the two chassis design. You could build a battery supply and switch between the two.
I just happen to have a large 100 amp hour battery with a power cable that has the same plug on it. So I can swap between the two.
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Is the battery 24v? If it's not you'd want to add another in series. The regulator filter, KMR, doesn't fully activate with under voltage. The problem with that is it'll reduce current from an infinite capacitor to like a 1500uf cap (sorta).
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I run two 26 AH batteries in series to get to 24V... plenty of power for dynamics, and it will run for days. Danny has always run bigger batteries, where I've always run separate components on separate batteries... phono pre, pre amp, dac, and now amp.
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Are these Amp and PS boards still available?
Steve
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"Are these Amp and PS boards still available?"
If Folsom does not have any of the amp & PS boards available
...I will be selling mine soon. They are new/unused and the PCBs are
still taped together as received. Also, after messaging with Folsom,
I have the Ok to pass along the BOM, assembly guide, etc... to the
buyer. I am selling because I simply don't have the time to do this
project. Cost would be the same as I paid for them plus USPS priority
shipping ($47 + 7.20 shipping). Please PM me if interested. Thanks
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Is the battery 24v? If it's not you'd want to add another in series. The regulator filter, KMR, doesn't fully activate with under voltage. The problem with that is it'll reduce current from an infinite capacitor to like a 1500uf cap (sorta).
Well, maybe I can't swap them then. I run my amps on 12 to 14 volts.
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Interesting build. Nice case. Maybe Folsom will build one and send it around on a tour. As I respect both Dave's and Danny's ears I'm curious as to Danny's opinion of sound.
If I could assemble one I would but not capable. TOUR. You will sell more.
charles
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Looks very nice! Anybody ever take some measurents on these? Do they produce enough power to drive speakers to fill a good sized room?
It depends on the efficiency of the speakers.
The amp can actually do 24w peaks, even though it's rated at 15w.
:duh:
I posted the question from my phone and should have elaborated - sorry.
It sounds like perhaps this version has been "tweeked" a bit by Dave Elledge (I miss him being here on AC....), and I wondered if the output changed.
I may take a look at the dedicated thread in the Cheap & Cheerful forum and see if it's something this fumble fingered amateur can tackle. I would be interested in finding out how different this version that Danny assembled is/sounds from the "stock" version - although I probably would not go with the Battery PS. If there is a big enough difference, I would then wonder if Dave and/or Danny might offer this as an upgrade option. :green:
Funds are kinda short at the moment, so I can't go overboard, but I would sure love to experiment with something other than what I currently have (Emotiva XPA-1) driving my LS6's (down to 50 Hz), or perhaps change things up a bit and experiment with them on the Super V's.
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I couldn't help myself. I made some A/B comparisons this morning. It is not really a fair comparisons yet as the new Folsum design has a lot of burn in ahead of it and it may come around a LOT. Again, the amps use the same chips.
As mono-blocks my amps have shorter speaker cables. They are just alike, but shorter, and I have always preferred them a little over the longer ones. The shorter ones also do not touch the floor either.
Also, my amps have no coupling caps at all. There is really nothing better than having no cap in the path. However, if I use either of my two outputs on my pre-amp that have a full range output then my amps won't come on. It leaves too much DC offset (I think) The coupling cap in the output of my pre-amp, that is a 3.3uF Jupiter cap, is just too big. But the third output on my pre-amp has a much smaller Sonicap Platinum and the amps work just fine with that output. So switching between the two amps means moving to a different output on the pre-amp too.
I would also mention that the input sensitivity is very different between the two amps. The Folsum model has a much higher input sensitivity level, and I do like that. But it also means that with A/B comparisons to my amps that I have to adjust the level on the servo subs with each switch.
The Folsum amp may have a little more output, drive, and dynamics, due to the higher voltage levels applied to the chip, but it was hard to tell much difference in that regard.
The Folsum amp also has a little larger coupling cap and plays a little lower than my amps. It works the lower woofers in the NX-Otica a little more and adds a little more body. I like that too.
The lower vocal region on the amps are really close. There is a little more body to the Folsum amp but not much. Upper vocals are softer for sure. It sounds a lot more like my tube amps in some ways than my chip amps. They are super musical and I could listen to them all day long.
However, at this point in the comparison (not much burn in time on them) they really give up upper level detail to my amps. My amps are sharper and sound a little more like a solid state amp. Air and space around everything is more present with mine. The Folsum amp is a lot more two dimensional verses mine. Mine present a deeper more layered sound stage. Some more time might change things in this regard a bit and I bet that it will.
I will say this though. If you aren't using one of the Folsum amps then you need to try one out. I think they are really tough to beat no matter how much money you spend. Granted you need reasonably efficient speakers, or you do not need high SPL levels. With the NX-Otica's (about 93.5db sensitivity) they may be all the power you ever want or need. For what the kit costs are it's a no brainer. They don't require a lot of parts either so spend your money on good quality wire, connectors, etc. It makes a difference.
I am looking forward to hearing what they do after more time, but so far a huge thumbs up from me. :thumb:
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Interesting build. Nice case. Maybe Folsom will build one and send it around on a tour. As I respect both Dave's and Danny's ears I'm curious as to Danny's opinion of sound.
If I could assemble one I would but not capable. TOUR. You will sell more.
charles
That happened 2 years ago :lol: . It was even used in a review of The Perfect Storm speakers from Vapor.
:duh:
I posted the question from my phone and should have elaborated - sorry.
It sounds like perhaps this version has been "tweeked" a bit by Dave Elledge (I miss him being here on AC....), and I wondered if the output changed.
I may take a look at the dedicated thread in the Cheap & Cheerful forum and see if it's something this fumble fingered amateur can tackle. I would be interested in finding out how different this version that Danny assembled is/sounds from the "stock" version - although I probably would not go with the Battery PS. If there is a big enough difference, I would then wonder if Dave and/or Danny might offer this as an upgrade option. :green:
Funds are kinda short at the moment, so I can't go overboard, but I would sure love to experiment with something other than what I currently have (Emotiva XPA-1) driving my LS6's (down to 50 Hz), or perhaps change things up a bit and experiment with them on the Super V's.
The output amount will still look like the datasheet for the TDA7297. It isn't really going to change. The work to make the 7297 is to provide the best power possible to the chip, and to carefully get the signal to it in the purest way. This includes a specialized grounding scheme that isn't normal but sounds vastly better.
It would probably make the Super V's sound amazing, as it would old add to their dynamic nature. The LS6's may sound good too, but the amount of reactance in speaker may make it a little more difficult for volume compare to 7297. You can change the LS6 reactance some with a simple mod, but it changes the FR some too.
Danny, it is interesting that the sensitivity is different, because the gain is identical between them. Mine can be made to make a more 3D image by making the KMR dirtier (more RF noise). It still helps the overall sound, but the additional RF will grow the 3D effect very quickly. I have intentionally kept the RF out, because I prefer the timbre a lot more without it, and dynamics in general seem more appealing to me without. I'm sure you will have differences to note as the caps change.
RF is very popular these days, with grounding boxes, etc. It is the sound many, many audiophiles like.
But also for me personally the stock 7297 versions were much to harsh, I have felt like the reduction in Enoise has helped with that to tame it into something I can listen to a lot.
BTW Danny, I have a fun experiment you could try with the two amps... I'd need to know which drivers and the wiring pattern they have for the NX-Otica's first. Then I'd recommend a bypass to try. You will explain to me how it changes the FR, but regardless I'd love to note the subjective experience from you.
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Danny, it is interesting that the sensitivity is different, because the gain is identical between them. Mine can be made to make a more 3D image by making the KMR dirtier (more RF noise). It still helps the overall sound, but the additional RF will grow the 3D effect very quickly. I have intentionally kept the RF out, because I prefer the timbre a lot more without it, and dynamics in general seem more appealing to me without. I'm sure you will have differences to note as the caps change.
The difference in input sensitivity must be because of the higher voltage level applied to the chip. My battery is at only 14 volts.
I like the low noise design and I might prefer the mid-range a little more in you design. But I think the filtering might be a bit much in the top end. It is eating into the detail level a little bit for sure. For instance the brush stokes on a snare drum that was light in the background we present and well placed in the sound stage with my amps, but with your design they tended to blend into the music and background.
The cap burn in effects are usually a softening or smoothing out for the most part. I usually don't get a big swing in detail level.
RF is very popular these days, with grounding boxes, etc. It is the sound many, many audiophiles like.
Typically I am not a big fan of RF noise either. I have experimented with small amounts of ESR paper on cables to block RF noise. And my speaker cables have a little ring of it on both ends.
BTW Danny, I have a fun experiment you could try with the two amps... I'd need to know which drivers and the wiring pattern they have for the NX-Otica's first. Then I'd recommend a bypass to try. You will explain to me how it changes the FR, but regardless I'd love to note the subjective experience from you.
Resistor by-pass on the inductors? The NX-Oticas use two of these in parallel. http://gr-research.com/m165xwoofer-2-1.aspx And four of these in series/parallel. http://gr-research.com/m130woofer-1.aspx What else do you need to know?
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Oh, and maybe try without the balanced PSU in the chain of AC to the amplifier. I have found balanced transformers have strange effects on it.. could be similar with whatever the special device you use has. It muted the top end.
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10uf - 8R, RC across the 165NQ's
15uf - 7R, RC across all of the 165's (at crossover would be the place to connect it)
It'll drop the 165NQ's FR some. Maybe a smaller inductor on them would help, or maybe it'd be bad for phase? I'm not sure. But regardless of the FR, give it a listen.
As in 8 ohm and 7 ohm?
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Oh, and maybe try without the balanced PSU in the chain of AC to the amplifier. I have found balanced transformers have strange effects on it.. could be similar with whatever the special device you use has. It muted the top end.
It could be. All chip and digital amps are really sensitivity to power cables and power supplies. I'll give it a shot and report back later today.
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Yes, 7 and 8 ohm.
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Yes, 7 and 8 ohm.
That would REALLY change the response.
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Yes. Try it anyway. You would think on the 165NQ's that it would have a large attenuation in their upper range, like it would sound low in volume, but if you try it you may find the opposite - that is what happened for me. And yes it is a very deliberate choice, not a random thing.
Playing with crossover sims I can only find that to correct the dip it causes, using a smaller inductor will get you closer to flat. But I'm not sure if that would cause phase issues or not.
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Yes. Try it anyway. You would think on the 165NQ's that it would have a large attenuation in their upper range, like it would sound low in volume, but if you try it you may find the opposite - that is what happened for me. And yes it is a very deliberate choice, not a random thing.
Playing with crossover sims I can only find that to correct the dip it causes, using a smaller inductor will get you closer to flat. But I'm not sure if that would cause phase issues or not.
They have a cap value almost that size in shunt already with no resistor.
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Oh, and maybe try without the balanced PSU in the chain of AC to the amplifier. I have found balanced transformers have strange effects on it.. could be similar with whatever the special device you use has. It muted the top end.
I just tried it with no balanced power supply and the result was almost the same. So now just a high quality power cable (with very little filtering) to the Uber Buss and an identical power cable after it.
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No resistor, then it's not the same thing. I know you got the parts :icon_lol: They won't use hardly any power, I use alligator leads to do it on my own (until I perma put something in) and they are sufficient.
You could try without the Uber, but I doubt it'd make a difference since the Uber is parallel and the PSU isn't SMPS. Perhaps the thing is I'd just have to be preset to know what exactly it sounds like. I tend to think the 7297 has really nice high frequency with snap to it.
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No resistor, then it's not the same thing. I know you got the parts :icon_lol: They won't use hardly any power, I use alligator leads to do it on my own (until I perma put something in) and they are sufficient.
I'll bring the parts over and clip them on another day.
You could try without the Uber, but I doubt it'd make a difference since the Uber is parallel and the PSU isn't SMPS. Perhaps the thing is I'd just have to be preset to know what exactly it sounds like. I tend to think the 7297 has really nice high frequency with snap to it.
This thing is starting to open up a little more. With the Best of Eva Cassidy I am liking the fuller body in the vocals over my amps. And there is a lot of airy noise in the live recordings that yours damps out. Still missing a little detail in the highs though. There is a clear difference in the top end.
I also noticed that if I push pause and listen to the speaker with nothing playing, but everything on, your amps are very quiet, but not as dead quiet as the battery powered amps. Yours has a very slight hiss. They are a little quieter than my battery powered tube amps though.
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I think the lack of air may be due to coupling caps that haven't been exercised much recently. I found that Platinums sound pretty good new and then backup a bunch for several hundred hours. I can send you some of the Jantzens that have a bit of time on them, but still need 30-40 hours. 1.8ufd is what I have settled upon as keeping the impulse response as well as an extended low end. In addition (I never thought I would say that I have a Solen cap that I like, but...) the Solen Silver 1000V 0.10 are excellent as bypasses.
Folsom's 7297 amp is a killer for the $$$ IF you have high sensitivity speakers. Running a pair in vertical bi-wire would be great if you need 3dB more power AND would free up the amps to excel in their own frequency ranges.
Since you are a wild man measure the amp for DC offset and see if it will be OK without the input caps. If you are using one of Gary's preamps with output caps you should be good to go.
I love great products from people that think outside of the box and are good people to boot!
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I think the lack of air may be due to coupling caps that haven't been exercised much recently. I found that Platinums sound pretty good new and then backup a bunch for several hundred hours.
That is possible, but I think the difference between the two amps is more than just cap break in up top.
I can send you some of the Jantzens that have a bit of time on them, but still need 30-40 hours. 1.8ufd is what I have settled upon as keeping the impulse response as well as an extended low end. In addition (I never thought I would say that I have a Solen cap that I like, but...) the Solen Silver 1000V 0.10 are excellent as bypasses.
Actually this makes me want to put some larger coupling caps in mine so they will play down lower. I am liking the additional body and more solid low end. I think the third output on my pre-amp has .047uF values. It's more ideal for those higher crossover points I've been using with some of these open baffle designs, but gives up too much in some applications for sure.
Folsom's 7297 amp is a killer for the $$$ IF you have high sensitivity speakers. Running a pair in vertical bi-wire would be great if you need 3dB more power AND would free up the amps to excel in their own frequency ranges.
For sure this is an excellent sounding amp. It makes me want to build a pair as mono-blocks with two outputs for bi-amping.
Since you are a wild an measure the amp for DC offset and see if it will be OK without the input caps. If you are using one of Gary's preamps with output caps you should be good to go.
If I use the .047uF cap output then no problem. If I use the 3.3uF cap output then the amps won't turn on.
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...Typically I am not a big fan of RF noise either. I have experimented with small amounts of ESR paper on cables to block RF noise.
And my speaker cables have a little ring of it on both ends.
Something like that?
(http://ultimateaudio.co.nz/wp-content/uploads/2015/10/FS-1-Speaker-Cables.png)
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Something like that?
(http://ultimateaudio.co.nz/wp-content/uploads/2015/10/FS-1-Speaker-Cables.png)
Used that way, but not implemented that way.
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Is it a secret? 8)
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Is it a secret? 8)
I have some in a 1" wide roll. Here it is in sheets. https://www.tweekgeek.com/stillpoints-ers-rfi-killer/
I settled on about a 1/2" wide strip wrapped around the cable right before it splits into a pair at the end. Tape it on and then heat shrink it with the end.
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In my cheap tweaked KEF Q100 coaxial speakers I have a Würth 150 kHz ferrite in the woofer cables -> more and better bass.
I tried first with tweeter+woofer cables but then the sound was equalized like U, too much highs!
(http://maty.galeon.com/WP-imagenes/kef-q100/KEF-Q100-filter-rockwool.jpg) (http://maty.galeon.com/WP-imagenes/kef-q100/KEF-Q100-filter-rockwool.jpg)
(http://maty.galeon.com/WP-imagenes/kef-q100/KEF-Q100-crossover-styroflex-bypass.jpg) (http://maty.galeon.com/WP-imagenes/kef-q100/KEF-Q100-crossover-styroflex-bypass.jpg)
and first in the RCA cables from my DAC (amp connection)
(http://maty.galeon.com/WP-imagenes/hard/RCA-cables-Wurth-150-khz-ferrites.jpg) (http://maty.galeon.com/WP-imagenes/hard/RCA-cables-Wurth-150-khz-ferrites.jpg)
It was trial and error and it works!
My inspiration to make the same with the speakers was Nuprime ST-10:
[IMG] http://maty.galeon.com/WP-imagenes/hard/Nuprime-ST-10-inside.jpg
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In-case anyone is wondering, I will say that my version only has power filtration. There is no manipulation of the signal in any way. It goes into the caps, and then into the chip, and back out of the chip to speakers. Not a single part between.
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In-case anyone is wondering, I will say that my version only has power filtration. There is no manipulation of the signal in any way. It goes into the caps, and then into the chip, and back out of the chip to speakers. Not a single part between.
That is why it sounds so good. :thumb: You took care to get the heart of the amp right (power supply) so the brains and muscles can do their jobs. That little 7297 chip amp is very, very good. Just stay away from the ebay knock off chips that don't measure up.
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Well, I think is a good idea to add a RF/EMI filter. I recommended Schaffner FN 9244B 1A.
[IMG] http://maty.galeon.com/WP-imagenes/hard/IEC-inlet-filter-Schaffner-FN_9244-specs.png
[IMG] http://maty.galeon.com/WP-imagenes/hard/IEC-inlet-filter-Schaffner-FN_9244-typical-filter-attenuation.png
[IMG] http://maty.galeon.com/WP-imagenes/hard/IEC-inlet-filter-Schaffner-FN_9244-cicuit.png
* B = medical
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I have some in a 1" wide roll. Here it is in sheets. https://www.tweekgeek.com/stillpoints-ers-rfi-killer/
I settled on about a 1/2" wide strip wrapped around the cable right before it splits into a pair at the end. Tape it on and then heat shrink it with the end.
Hi,
These ERS-RFI are interesting to DIY apps.
According the link its made of:
carbon fibers of various lengths and sizes. Using a proprietary method, these fibers are coated with metals, such as nickel.
Do you know if its Carbon Fiber or Carbon Steel?
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Hi,
These ERS-RFI are interesting to DIY apps.
According the link its made of:
carbon fibers of various lengths and sizes. Using a proprietary method, these fibers are coated with metals, such as nickel.
Do you know if its Carbon Fiber or Carbon Steel?
Carbon fiber.
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10 Mhz - 49 dB
The most important in audio is < 1 Mhz, aka RF. Better with Schaffner RF/EMI filters and Würth 150 kHz ferrites.
By the way, carbon fiber dissipates hot very well too. And it is a very good idea the nickel.
> 1 MHz, aka EMI, useful with video. Cheap ferrites.
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Carbon fiber.
Thanks Bro, I will look a local substitute, maybe the price be better.
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Danny Can you share more info on your amps.
Is it battery only?
Is it tube?
Dimensions?
Weight?
Power output?
RCA and XLR or just RCA inputs?
Photo front and back?
Mono block?
It would be nice to be off the grid, but if the amp can be turned off that would be ok also. Amps that sound best when left on is not for me much longer me thinks.
The Folsom and yours both are very interesting.
Thanks
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The tubes system
Past
https://www.stereophile.com/rmaf2007/101407gr/index.html
(https://www.stereophile.com/images/gr-450.jpg)
http://www.stereomojo.com/Luminance%20KST-150%20Amplifier%20Review/LuminanceKST-150AmplifierReview.htm
(http://www.stereomojo.com/Luminance%20KST-150%20Amplifier%20Review/images/bigblue3.jpg)
Present
(http://gr-research.com/pics/rmafshowpic6.jpg)
(http://b0.ultimist.com/photos/topic/4/10449_1_IMG_9191-dodd-audio-amplifier_large.jpg)
(http://b2.ultimist.com/photos/topic/4/10451_1_IMG_9193-dodd-audio-preamp_huge.jpg)
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A big difference between ours is that mine runs at 17.8v, for full power. Danny's run at 12v, maybe 14v?
It's absolute luck if you get an eBay chip that will tolerate more than 12v for more than a week, and even then don't expect it to run near 18v. Where as I accidentally had a chip running on 22v for a couple weeks, and it worked fine after I got the voltage back down too. The authentic test passed chips are much more robust for tolerance of voltage. This may be important if you're trying to get full power, like you run the speaker fullrange.
Danny probably has the link to his. One advantage his has is that he enclosure is wood between the binding posts, where as it is metal on the one he built for mine. At least I found a difference in SQ, by eliminating the RF inducing situation of not allowing the output + and - fields to interact at the point where they cross the chassis. In one my most recent posts I drew pictures (http://www.audiocircle.com/index.php?topic=138229.msg1670797#msg1670797) what I mean. It's funny because otherwise the metal enclosures provide shielding, so I'm not saying metal enclosures are inherently bad.
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Danny Can you share more info on your amps.
Is it battery only?
Is it tube?
Dimensions?
Weight?
Power output?
RCA and XLR or just RCA inputs?
Photo front and back?
Mono block?
It would be nice to be off the grid, but if the amp can be turned off that would be ok also. Amps that sound best when left on is not for me much longer me thinks.
The Folsom and yours both are very interesting.
Thanks
I built this little pair nearly 4 years ago when it was discovered just how good these little chips were. Mine were the cheap version purchased from E-Bay. You can see everything here: http://www.audiocircle.com/index.php?topic=124981.msg1317309#msg1317309
I have them both plugged into a 100 amp hour Power Sonic battery.
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Thanks Danny. We talked a little over a year ago. At that time it sounded like you were going to be coming out with an amp. I thought this was it.
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Okay now that these things have played for a day they have really opened up a lot more. The top end and imaging is now almost the same as my amps. I'd say they were about 98% there. I little more and they will be dead on each other. It's amazing what some burn in time will do.
I also tried the Folsom amp with the 100 amp hour Power Sonic battery. It has less voltage than the A/C power supply but the sound quality is really close. They are almost dead on. In just a few tracks the battery had slightly better upper end and imaging (a little more air), but very, very slight. I A/Bed them back and forth about 20 times. Fun stuff!
The odd thing to me still is the difference in input sensitivity still. I have to turn my amps up a little more to equal the Folsum amp in volume. And when going between the A/C power supply and the battery the output level on the Folsum amp the output stayed the same.
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If you plug yours into the other output on the preamp, do you get different volume than the 3.3uf? The different preamp outputs are the only thing that make any real sense. Putting a second capacitor between the chips isn't an attenuation device in itself. The chip is internally set for gain.
The battery will provide a little more RF in order to enhance some high frequency character. (more air = the most common benefit of some RF)
The TL431 regulator can be swapped for one from Fairchild to dirty up the supply a little, which will give a little more enhanced character from RF. But it will maintain filtration of mostly lower frequency stuff that makes the amp not sound as good. "warmer" might be the best description.
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If you plug yours into the other output on the preamp, do you get different volume than the 3.3uf? The different preamp outputs are the only thing that make any real sense. Putting a second capacitor between the chips isn't an attenuation device in itself. The chip is internally set for gain.
Mine won't play plugged into the the output with the 3.3uF output caps unless I plug in a filter cap right at the amp. I keep a .022uF, a .033uF, and .047uF inline filter handy for different speakers.
There is clearly an output difference. I don't know why.
I just listened to to Vienna Teng recorded live, using the your amp. I went back and forth several times using the A/C power supply and the battery again. Her voice is slightly more chesty and with a little more body with the A/C power supply and slightly more open and airy with the battery.
I wish everyone here could hear this system right now. Unbelievable!
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hey danny.
do you have any of those cases for sale?
what are the dimensions?
thanks,
drmike
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hey danny.
do you have any of those cases for sale?
what are the dimensions?
thanks,
drmike
Yeah, I have a lot of them. I'll make some deal on them.
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Yeah, I have a lot of them. I'll make some deal on them.
Danny, shoot me a cost for 4. Thanks. It'll be good just to have a GD design on hand other than my pre and amp.
I loved that man. He was an inspiration in chasing battery power and just a hoot to hang out with talking audio. I miss him muchly.
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When you shoot Dave a PM, send me one too. I could use a couple of those as well.
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+1
Me too please. :)
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Danny,
You can add me to the case list also.
Mike
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Yeah, I have a lot of them. I'll make some deal on them.
I need 2 please.
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Fun to see the Folsom amp still gets the attention and great reviews it deserves! :thumb:
Nice build!
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Any thoughts on integrating these amps INTO the crossover of your 2-way models? I could see a single chip amp "bi-amping" one of your speakers (one channel for the tweeter, one channel for the woofer). The speaker binding posts (or tube connectors) would be replaced with a single RCA connector and an input for power.
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Any thoughts on integrating these amps INTO the crossover of your 2-way models? I could see a single chip amp "bi-amping" one of your speakers (one channel for the tweeter, one channel for the woofer). The speaker binding posts (or tube connectors) would be replaced with a single RCA connector and an input for power.
It would be real easy to make that happen on just about any model we offer.
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It would be real easy to make that happen on just about any model we offer.
Why stop there? Throw in a "do no harm" volume control and you've got a true audiophile integrated speaker system. Just plug in a source via a long pair of XLR cables to the speakers, and press, "play."
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Next thing all y'all are going to tell Danny to design line level crossovers for all his kits and sell kit-form true active systems... ;)
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My newer amp uses the 7293 to get some more serious power, but it doesn't sound like the 7293 because it has specialized feedback that is error correcting. It's sensitive enough to compare the incoming and outgoing signal, for voltage tracking, but not when it's own self power is moving. That's why it is battery/solar powered feedback.
Keep me informed as to how development of this goes.
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Okay, for you guys asking about these chassis's.
(http://gr-research.com/amps/folsom3.jpg)
I looked up the all the cost that I have in these. There was raw Aluminum, CNC machining, and engraving. The front baffles say Commemorative Designs in honor of Gary Dodd as he designed these.
I have $115 in each chassis.
I can throw in the Cardas RCA's for $10 each. That's less than the retail for.
The Neutrik connectors are $15 a set (male and female).
And the tube connectors are $59 a set.
These little chassis are perfect for the Folsom amps.
I also have a bunch of the TDA7850 chip sets and circuit boards. These are what the chassis's were designed for. It's a similar chip set, but will output 50 watts per channel into four channels. You can vary the input coupling cap value to allow one set of outputs to be full range and the other can have reduced low frequency (filtered lows). That's what Gary was going to do with them.
http://html.alldatasheet.com/html-pdf/233387/STMICROELECTRONICS/TDA7850/1944/1/TDA7850.html
I can throw in these chip sets and boards for another $20.
Oh yeah, the internal space is 6" by 5" and 2.375" tall.
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Gentlemen, I have once again been disinvited to post on Audio Circle by your Imperious Leader JohnR. If anyone needs or would like help with the Folsom 7297 amp, please PM Danny and he can give you my email address.
This amp is an overachiever at its price point and a great overall performer at any price.
Kudos, Jeremy!
Bye, ya'll.
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Hi, I am interested in these, and I have come to the conclusion that I'm a little lost. I know it needs a chassis, but I'm lost on the rest. Jeremy sends a parts list, directions and a psu board and the amp board. I can follow directions and solder, but outside of that, noob. After ordering the mouser parts list, will I need anything else to plug it in and go? I read several of you use batteries and don't know how to do that.
I have built 4 gr kits and a bottlehead amp by watching and learning. What else do I need to know before I order one of these?
Thanks for any help.
Ben
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The BOM does not include the connectors. It has a few suggestions. You also need a heatsink, which I mention can be got at heatsinkusa if you want something specific cut to size.
You also have to buy wire.
You may find this topic useful. https://www.audiocircle.com/index.php?topic=138229.0
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Don't know about several of us using batteries, but I am. Simply take two 12V SLA batteries and connect in series to up the voltage to 24V and connect to the power input on the board.
Don't get in a hurry and you should have no problems. The board is well marked.
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I did the mod that eliminates the chassis bridge between the +/- speaker outputs and have found it to be a great sounding modification.
Isn’t difficult and highly recommended! Cool, it is: better sound from an over-achiever! Thanks, Jeremy!
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Don't know about several of us using batteries, but I am. Simply take two 12V SLA batteries and connect in series to up the voltage to 24V and connect to the power input on the board.
Don't get in a hurry and you should have no problems. The board is well marked.
Would you elaborate a bit more on the batteries you use? What min Ah requirement for a reasonable run time, and what are you using for a charger. I have built several of these amps using SMPS's and with Transformer/Antipole PS, but never with batteries.
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I"m using two 18 AH batteries. They will power the unit for a week or probably two when used an hour or so a day. At that time I'll put in a couple of 5 AH's while charging the bigger batteries, and they'll run for than a couple of listening sessions. I use a CTEK 12V charger. I have a switch between the 18 AH batteries. Most times I'll simply charge one at a time when not playing, never taking out the batteries.
I've also used a couple of 28 AH batteries that power my Dodd pre and Dodd phono stage in my main system. I can't hear a difference in dynamics or quality between them and the 18 AH.
These little amps are extremely efficient. I'd bet you could use a couple of 7 AH batteries and have a dynamic system that would run for days or even a week.
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Okay, for you guys asking about these chassis's.
(http://gr-research.com/amps/folsom3.jpg)
I looked up the all the cost that I have in these. There was raw Aluminum, CNC machining, and engraving. The front baffles say Commemorative Designs in honor of Gary Dodd as he designed these.
I have $115 in each chassis.
I can throw in the Cardas RCA's for $10 each. That's less than the retail for.
The Neutrik connectors are $15 a set (male and female).
And the tube connectors are $59 a set.
These little chassis are perfect for the Folsom amps.
I also have a bunch of the TDA7850 chip sets and circuit boards. These are what the chassis's were designed for. It's a similar chip set, but will output 50 watts per channel into four channels. You can vary the input coupling cap value to allow one set of outputs to be full range and the other can have reduced low frequency (filtered lows). That's what Gary was going to do with them.
http://html.alldatasheet.com/html-pdf/233387/STMICROELECTRONICS/TDA7850/1944/1/TDA7850.html
I can throw in these chip sets and boards for another $20.
Oh yeah, the internal space is 6" by 5" and 2.375" tall.
Somehow, I missed this post. I am interested but have several questions after re-reading this thread and parts of a couple others.
Danny, are these chassis' still available?
I'm guessing that they are best used as mono so need 2 for a Stereo?
I read a lot about different values for the different parts. How do you determine which values will best suit your system?
Is the value dependent on your speakers, your preamp, or a combination of the 2?
What other factors should be considered?
Any final conclusion on battery vs AC SQ? (I am interested in AC - any way to maximize? I have an UberBUSS)
Would there be any way a single one would sound good on the Super V's and the LS6's? (at a lower volume).
I would probably want to have the option of limiting the output of the low frequency via the input coupling cap.
Thanks
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Somehow, I missed this post. I am interested but have several questions after re-reading this thread and parts of a couple others.
Danny, are these chassis' still available?
Yes. I have a lot of them.
I'm guessing that they are best used as mono so need 2 for a Stereo?
For me it is worth the extra money to make mono-blocks out of them just to keep speaker cable lengths shorter. I can spend more on longer speaker cables than it cost to build another amp (almost). Plus the amps can be two channel amps for bi-amping or different sized coupling caps can be used to vary the low end roll off. So you can have a full range channel and a channel with a -3db at whatever you want it to be.
I read a lot about different values for the different parts. How do you determine which values will best suit your system?
Are you referring to input coupling caps? If so the value depends on how much you want to roll off the bottom end.
And spend the money of good RCA connectors, tube connectors and wire. It can really make a difference. And I stock most of that.
Is the value dependent on your speakers, your preamp, or a combination of the 2?
The input impedance of the amp and your target roll off determines the value. For this amp I think it is 25k ohms.
So a .022uF value will be -3db down at 289Hz.
A .033uF value will be -3db down at 192Hz.
A .047uF value will be -3db down at 135Hz.
A .068uF value will be -3db down at 93Hz.
A .1uF value will be -3db down at 63Hz.
A .22uF value will be -3db down at 29Hz.
A .33uF value will be -3db down at 19Hz.
A .47uF value will be -3db down at 13.5Hz.
A 1.0uF value will be -3db down at 6Hz.
What other factors should be considered?
Just a target roll off.
Any final conclusion on battery vs AC SQ? (I am interested in AC - any way to maximize? I have an UberBUSS)
I've gone back and forth quite a bit and in my system the battery sounds better. And with the power supply I used really good cables, an Uber Buss, and a Dodd Audio balanced power supply. I still preferred the battery. However, not all batteries are the same. Mine is a 100 amp hour Power Sonic.
Would there be any way a single one would sound good on the Super V's and the LS6's? (at a lower volume).
The LS-6's are going to like more power, but they will drive the Super-V's easily to good levels.
I would probably want to have the option of limiting the output of the low frequency via the input coupling cap.
Piece of cake. See above. The limiting of current demand from it will give it a little more head room too.
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I use 1.5uf, 1uf still has audible roll off even at 6hz corner. (who knows why...)
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I use 1.5uf, 1uf still has audible roll off even at 6hz corner. (who knows why...)
:scratch:
6 Hz has audible roll off? I have no speaker capable of producing anything audible at 6 Hz. Am I missing something?
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For a single pole filter, a -3dB down point at 6Hz means that it is -0.1dB down at 60Hz.
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For a single pole filter, a -3dB down point at 6Hz means that it is -0.1dB down at 60Hz.
Thanks Rich. I'm guessing that would be tough for me to notice.
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Yes. I have a lot of them.
For me it is worth the extra money to make mono-blocks out of them just to keep speaker cable lengths shorter. I can spend more on longer speaker cables than it cost to build another amp (almost). Plus the amps can be two channel amps for bi-amping or different sized coupling caps can be used to vary the low end roll off. So you can have a full range channel and a channel with a -3db at whatever you want it to be.
Are you referring to input coupling caps? If so the value depends on how much you want to roll off the bottom end.
And spend the money of good RCA connectors, tube connectors and wire. It can really make a difference. And I stock most of that.
The input impedance of the amp and your target roll off determines the value. For this amp I think it is 25k ohms.
So a .022uF value will be -3db down at 289Hz.
A .033uF value will be -3db down at 192Hz.
A .047uF value will be -3db down at 135Hz.
A .068uF value will be -3db down at 93Hz.
A .1uF value will be -3db down at 63Hz.
A .22uF value will be -3db down at 29Hz.
A .33uF value will be -3db down at 19Hz.
A .47uF value will be -3db down at 13.5Hz.
A 1.0uF value will be -3db down at 6Hz.
Just a target roll off.
I've gone back and forth quite a bit and in my system the battery sounds better. And with the power supply I used really good cables, an Uber Buss, and a Dodd Audio balanced power supply. I still preferred the battery. However, not all batteries are the same. Mine is a 100 amp hour Power Sonic.
The LS-6's are going to like more power, but they will drive the Super-V's easily to good levels.
Piece of cake. See above. The limiting of current demand from it will give it a little more head room too.
If I understand everything correctly, I would be looking at somewhere between .1 & .15 uF (I'm currently using the Fmods at 50 Hz when running the LS6s).
What else would I need besides the Chassis and the Chip boards to build out 2 Mono blocks? Separate boxes for the PS and all of the other electronics for the PS and the Amp box?
Trying to figure out if I can swing this with good RCA's, tube connectors and Wire - what's the total cost to get 2 channels of amplification?
(and how much my soldering skills and ability to read a circuit diagram would be taxed :green:)
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Ryan from Vapor could hear the roll off with 1uf. So it was not just me.
The amp may exaggerate it a little, especially since it has a -3db at 20hz.
But all you have to do is add a little more capacitance and all is good.
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Ryan from Vapor could hear the roll off with 1uf. So it was not just me.
The amp may exaggerate it a little, especially since it has a -3db at 20hz.
But all you have to do is add a little more capacitance and all is good.
...This seemed to work for me... :thumb:
(https://www.audiocircle.com/image.php?id=181363)
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In building the Folsom amp, I understand quality of results vary considerably with the choice of caps used. What caps would some of you recommend I order/use? I lean more towards the "cheap and cheerful" approach as opposed to "no holds barred" . Let me say my caps budget, for the amp and the anti-pole, is $50.
Pete
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In building the Folsom amp, I understand quality of results vary considerably with the choice of caps used. What caps would some of you recommend I order/use? I lean more towards the "cheap and cheerful" approach as opposed to "no holds barred" . Let me say my caps budget, for the amp and the anti-pole, is $50.
Pete
I am happy with Clarity ESA caps.
https://www.partsconnexion.com/CLARITY-74834.html
(https://www.audiocircle.com/image.php?id=181662)
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I did the mod that eliminates the chassis bridge between the +/- speaker outputs and have found it to be a great sounding modification.
Isn’t difficult and highly recommended! Cool, it is: better sound from an over-achiever! Thanks, Jeremy!
More on this Mod?
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In building the Folsom amp, I understand quality of results vary considerably with the choice of caps used. What caps would some of you recommend I order/use? I lean more towards the "cheap and cheerful" approach as opposed to "no holds barred" . Let me say my caps budget, for the amp and the anti-pole, is $50.
Pete
Since the value needed is quite small, it is worth spending a little more to get high quality caps.
I like the Jupiter caps and Sonicap Platinum's myself.
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More on this Mod?
https://www.audiocircle.com/index.php?topic=138229.msg1670633#msg1670633 (https://www.audiocircle.com/index.php?topic=138229.msg1670633#msg1670633)
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Danny, have you (or anyone else) tried the new Folsom 7293 amp yet? Looking forward to hearing some impressions.
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Danny, have you (or anyone else) tried the new Folsom 7293 amp yet? Looking forward to hearing some impressions.
Not yet, but I'd love to try it.
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Not yet, but I'd love to try it.
I have one and am only a few hundred miles from North Texas, if you want to hear it let me know.
(https://www.audiocircle.com/image.php?id=200738)
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I have one and am only a few hundred miles from North Texas, if you want to hear it let me know.
(https://www.audiocircle.com/image.php?id=200738)
I'd love to hear it.
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I have one and am only a few hundred miles from North Texas, if you want to hear it let me know.
Nice. I just ordered boards and parts for a dual mono setup. What are you using as a preamp?
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I'd love to hear it.
I get back in town in a week, we can setup something.
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Nice. I just ordered boards and parts for a dual mono setup. What are you using as a preamp?
I have a Modwright Transporter that I use as pre-amp. This project while big is worth it. What case do you plan to use?
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Hi! Are there still boards for sale? Does anyone know how to order them?
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I ordered a set of boards a few days ago.
https://www.diyaudio.com/forums/group-buys/338275-folsom-ec7293-pvi-powered-frontend-60-120w-8-4ohm.html
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I have been doing a bit of research on these amps as well. There are detailed build and part selection discussions at diyaudio.com.
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I ordered a set of boards a few days ago.
https://www.diyaudio.com/forums/group-buys/338275-folsom-ec7293-pvi-powered-frontend-60-120w-8-4ohm.html
Nice! Will check it out! :D
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How to contact me: folsom.jeremyh@gmail.com
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Morning Danny,
I am interested in the approach you came up with for powering your system. It is a fascinating departure from what I would have considered for a high end system. I am going to experiment with the idea and have ordered the Folsom pcb kits as a start.
What I am wondering is how to approach the evolution on the preamp side. Given that Dodd equipment is not available, would you have any quidance as to how one could best explore preamp options? Are there other tube ideas out there that are similar? Or perhaps, solid state. (I am getting the builder bug, so thinking of kit or DIY type solutions.)
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These are nice sounding kits.
http://www.tubes4hifi.com/pre11.htm (http://www.tubes4hifi.com/pre11.htm)
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Morning Danny,
I am interested in the approach you came up with for powering your system. It is a fascinating departure from what I would have considered for a high end system. I am going to experiment with the idea and have ordered the Folsom pcb kits as a start.
What I am wondering is how to approach the evolution on the preamp side. Given that Dodd equipment is not available, would you have any quidance as to how one could best explore preamp options? Are there other tube ideas out there that are similar? Or perhaps, solid state. (I am getting the builder bug, so thinking of kit or DIY type solutions.)
I really don't know of any good battery powered pre-amps that I could recommend.
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I really don't know of any good battery powered pre-amps that I could recommend.
It’s a shame you couldn’t sell 12v Dodd preamps or have someone else carry on the designs.
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Watch the trading post... they do pop up from time to time
jay
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It’s a shame you couldn’t sell 12v Dodd preamps or have someone else carry on the designs.
That might happen one of these days.
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A little bit off topic:
Has anyone built the EC7293?
I have the boards and have started buying up on parts. Just waiting for time and courage. Would love to see and hear how others have approached it and how they like it.
I will start a build thread when I get that far.
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A little bit off topic:
Has anyone built the EC7293?
I have the boards and have started buying up on parts. Just waiting for time and courage. Would love to see and hear how others have approached it and how they like it.
I will start a build thread when I get that far.
I'm in the same boat. I also have the EC7293 and will soon start my build. I'll follow your post and chime in with my progress. I will be using it with a Tortuga LDR300v25 buffered preamp.
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I'm in the same boat. I also have the EC7293 and will soon start my build. I'll follow your post and chime in with my progress. I will be using it with a Tortuga LDR300v25 buffered preamp.
Nice! I will be using it with a Holographic Audio Pre 25 preamp. Really nice Swedish hifi-gear. Gets very much out the way of the source.
Pretty cheapo but nice turntable with Nagaoka pick up, and an Arcam dac that really wants to move to the desktop and make room for something more refined... But that'll have be a project further down the road. Amp first!
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I'll be around to answer questions :wink:
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:thumb: :thumb: :thumb:
I'll be around to answer questions :wink: