I put together the little Folsom amp.

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dBe

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Re: I put together the little Folsom amp.
« Reply #40 on: 8 Mar 2018, 03:48 am »
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!
« Last Edit: 8 Mar 2018, 08:20 pm by dBe »

Danny Richie

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Re: I put together the little Folsom amp.
« Reply #41 on: 8 Mar 2018, 03:16 pm »
Quote
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.

Quote
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.

Quote
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.

Quote
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.

maty

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Re: I put together the little Folsom amp.
« Reply #42 on: 8 Mar 2018, 03:39 pm »
...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?



Danny Richie

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Re: I put together the little Folsom amp.
« Reply #43 on: 8 Mar 2018, 03:51 pm »
Something like that?


Used that way, but not implemented that way.

maty

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Re: I put together the little Folsom amp.
« Reply #44 on: 8 Mar 2018, 03:56 pm »
Is it a secret?  8)

Danny Richie

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Re: I put together the little Folsom amp.
« Reply #45 on: 8 Mar 2018, 05:00 pm »
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.

maty

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Re: I put together the little Folsom amp.
« Reply #46 on: 8 Mar 2018, 05:15 pm »
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!




and first in the RCA cables from my DAC (amp connection)


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

Folsom

Re: I put together the little Folsom amp.
« Reply #47 on: 8 Mar 2018, 07:26 pm »
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.

dBe

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Re: I put together the little Folsom amp.
« Reply #48 on: 8 Mar 2018, 08:19 pm »
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.


FullRangeMan

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Re: I put together the little Folsom amp.
« Reply #50 on: 8 Mar 2018, 08:44 pm »
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?

dBe

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Re: I put together the little Folsom amp.
« Reply #51 on: 8 Mar 2018, 08:46 pm »
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.

maty

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Re: I put together the little Folsom amp.
« Reply #52 on: 8 Mar 2018, 08:54 pm »
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.

FullRangeMan

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Re: I put together the little Folsom amp.
« Reply #53 on: 8 Mar 2018, 08:56 pm »
Carbon fiber.
Thanks Bro, I will look a local substitute, maybe the price be better.

saygrr

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Re: I put together the little Folsom amp.
« Reply #54 on: 8 Mar 2018, 09:16 pm »
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


Folsom

Re: I put together the little Folsom amp.
« Reply #56 on: 8 Mar 2018, 09:27 pm »
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 what I mean. It's funny because otherwise the metal enclosures provide shielding, so I'm not saying metal enclosures are inherently bad.

Danny Richie

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Re: I put together the little Folsom amp.
« Reply #57 on: 8 Mar 2018, 09:40 pm »
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.

saygrr

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Re: I put together the little Folsom amp.
« Reply #58 on: 9 Mar 2018, 12:00 am »
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.

Danny Richie

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Re: I put together the little Folsom amp.
« Reply #59 on: 9 Mar 2018, 12:21 am »
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.