Folsom's great little 7297 Chip Amp

Odal3 · « **Reply #720 on:** 11 Nov 2016, 08:46 pm »

Wow - Master piece!

limits · « **Reply #721 on:** 11 Nov 2016, 10:08 pm »

Very nice, Larry! Hey--What's up with those fancy input caps?

It looks as good as I bet it sounds!

shadowlight · « **Reply #722 on:** 11 Nov 2016, 11:55 pm »

@lacro, wow that is one awesome build.

Captainhemo · « **Reply #723 on:** 12 Nov 2016, 01:44 am »

Awsome Larry

Told ya that there trans had " magic pixie dust" in it

I've gotta get going on mine....
jay

BRN · « **Reply #724 on:** 12 Nov 2016, 01:51 am »

That is one beautiful looking amp. Great job.

lacro · « **Reply #725 on:** 12 Nov 2016, 02:09 pm »

Guys: Thanks for the kind words! I am really happy with results of the build, and most of all the amazing sound it produces

Also, a special thanks to shadowlight, and Captainhemo for their generous donation of parts

Quote from: limits on 11 Nov 2016, 10:08 pm

Hey--What's up with those fancy input caps?

limits: The fancy input caps are just an experiment. Clarity caps are on sale (50% off) at Parts Connection, so they were not much $ I don't know how much the caps are contributing to the great sound with this build, but they don't seem to be hurting the sound. They are keepers!

Captainhemo · « **Reply #726 on:** 12 Nov 2016, 04:58 pm »

Like I said Larry, the final result is great, I'll be using your pics for ideas when I finally lay mine out in a chassis.

For those interested in maybe tryng some different input caps, Parts Coonexion is having a 25% off sale Sat Nov 26 but IIRC, it's only on for 1/2 day.

jay

Odal3 · « **Reply #727 on:** 12 Nov 2016, 06:55 pm »

I soldered 2.5in wire between DAC output and folsom board amp and for me it helped clean up the sound a notch. I used very low cost IC before so it wasn't too surprising it would be better. The source is a RPI streamer with a direct connected I2S DAC so there are now no removable IC in the signal chain.

I'm currently using software volume control for convinience (maybe not ideal) so I don't have the recommended DACT hardware volume control installed.

Many say using a preamp often sounds better than what a DAC itself can produce so are there any recommended tweaks to compensate for this? Buffer? Anything else specific to the Folsom amp?

Folsom · « **Reply #728 on:** 12 Nov 2016, 07:01 pm »

If you're feeding direct from the DAC you're probably fine. The DACT volume control is excellent but a buffer between it and the amp is best. However you have little need feeding directly from a DAC, so long as the DAC has good outputs.

If you want a buffer I already recommended a very good one. It is however a little more advanced, requiring some work with a multimeter and such to get it correct.

Odal3 · « **Reply #729 on:** 13 Nov 2016, 03:24 am »

Thanks!

The advanced part kind of scared me away last time.

lacro · « **Reply #730 on:** 13 Nov 2016, 01:11 pm »

I too am interested in the Kuartlotron, but the "advanced" statement has me wondering as well. Is there more than adjusting the correct resistance on the trimmers that makes it advanced? If it makes your already superb sounding amp sound even better, I've got to have one! Jeremy, would you consider putting together a brief "tutorial for dummies"

Folsom · « **Reply #731 on:** 13 Nov 2016, 04:53 pm »

It's more advanced because I haven't made a tutorial of any kind, and you need to measure and adjust while it's turned on, and not hooked up to anything. I'd consider making one if someone sent me all the parts and a pair of the (new) PCB boards. The other issue is that you have to provide all of the PSU parts on your own. I could provide a few suggestions but that's about all.

drew_t · « **Reply #732 on:** 15 Nov 2016, 08:50 pm »

Quote from: lacro on 11 Nov 2016, 06:27 pm

Just completed my latest Folsom amp. I couldn't find a case I liked, so I built my own.

Nice build, but how does the heat get out?

lacro · « **Reply #733 on:** 16 Nov 2016, 01:14 pm »

Quote from: drew_t on 15 Nov 2016, 08:50 pm

Nice build, but how does the heat get out?

Good observation. The carbon fiber top is intentionally not attached to the case (floating). I purposefully drilled holes between the fins of the heat sink on the bottom. My intention was to drill vent holes in the top; just prop it up similar to a piano top, or remove it altogether during use. However, for some unknown reason, this build does not produce heat (top on), even after a 10 hour high level listening session. I can't explain why as all previous Folsom amps I have built have produced significant heat. I like the clean look of no holes in the top, but, I still have the above mentioned options if ever needed.

Floating top:

S Clark · « **Reply #734 on:** 16 Nov 2016, 02:11 pm »

My latest version also doesn't create any heat to speak of- I can put my finger directly to the heat sink after hours of plaing. It's enclosed in a hinged Cuervo 1800 box, but I don't feel the need to open while playing.

Tortorgia · « **Reply #735 on:** 27 Nov 2016, 04:39 am »

Can anyone share a link on where to get the board and an updated parts list? please

Folsom · « **Reply #736 on:** 28 Nov 2016, 06:57 am »

I'm out of boards for now.

zek · « **Reply #737 on:** 28 Nov 2016, 11:10 pm »

Is it possible to get PCBs in pdf and a list of materials for amp and PSU?

Folsom · « **Reply #738 on:** 28 Nov 2016, 11:24 pm »

Nope.

zek · « **Reply #739 on:** 29 Nov 2016, 04:55 pm »

Unfortunately.