I put together the little Folsom amp.

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S Clark

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Re: I put together the little Folsom amp.
« Reply #20 on: 7 Mar 2018, 05:16 am »
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. 

SteveKi

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Re: I put together the little Folsom amp.
« Reply #21 on: 7 Mar 2018, 12:21 pm »
Are these Amp and PS boards still available?
Steve

Oscillate

Re: I put together the little Folsom amp.
« Reply #22 on: 7 Mar 2018, 01:39 pm »
"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

Danny Richie

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Re: I put together the little Folsom amp.
« Reply #23 on: 7 Mar 2018, 03:01 pm »
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.

rollo

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Re: I put together the little Folsom amp.
« Reply #24 on: 7 Mar 2018, 03:16 pm »
   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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Re: I put together the little Folsom amp.
« Reply #25 on: 7 Mar 2018, 04:25 pm »
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.

Danny Richie

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Re: I put together the little Folsom amp.
« Reply #26 on: 7 Mar 2018, 07:11 pm »
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:

Folsom

Re: I put together the little Folsom amp.
« Reply #27 on: 7 Mar 2018, 08:11 pm »
   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. 

Danny Richie

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Re: I put together the little Folsom amp.
« Reply #28 on: 7 Mar 2018, 08:43 pm »
Quote
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.

Quote
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.

Quote
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?

Folsom

Re: I put together the little Folsom amp.
« Reply #29 on: 7 Mar 2018, 09:08 pm »
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.


Folsom

Re: I put together the little Folsom amp.
« Reply #30 on: 7 Mar 2018, 09:10 pm »
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.

Danny Richie

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Re: I put together the little Folsom amp.
« Reply #31 on: 7 Mar 2018, 09:17 pm »
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?

Danny Richie

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Re: I put together the little Folsom amp.
« Reply #32 on: 7 Mar 2018, 09:18 pm »
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.

Folsom

Re: I put together the little Folsom amp.
« Reply #33 on: 7 Mar 2018, 09:27 pm »
Yes, 7 and 8 ohm.

Danny Richie

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Re: I put together the little Folsom amp.
« Reply #34 on: 7 Mar 2018, 10:15 pm »
Yes, 7 and 8 ohm.

That would REALLY change the response.

Folsom

Re: I put together the little Folsom amp.
« Reply #35 on: 7 Mar 2018, 10:18 pm »
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.

Danny Richie

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Re: I put together the little Folsom amp.
« Reply #36 on: 8 Mar 2018, 01:27 am »
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.

Danny Richie

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Re: I put together the little Folsom amp.
« Reply #37 on: 8 Mar 2018, 01:29 am »
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.

Folsom

Re: I put together the little Folsom amp.
« Reply #38 on: 8 Mar 2018, 01:48 am »
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.

Danny Richie

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Re: I put together the little Folsom amp.
« Reply #39 on: 8 Mar 2018, 02:06 am »
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.

Quote
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.