Folsom's great little 7297 Chip Amp

Folsom · « **Reply #340 on:** 3 Jun 2016, 06:14 am »

BRN, I think you're the first person to use the Nichicon FP caps instead of the Panasonic's. I'm excited to hear about what you think.

lacro · « **Reply #341 on:** 3 Jun 2016, 01:45 pm »

Nice clean work, looks great

No ventilation holes?

lokie · « **Reply #342 on:** 3 Jun 2016, 02:18 pm »

Sorry for being such a putz but does anyone have one of these for sale? or starting a build and want's to build an extra one simultaneously?

Thanks

happyrabbit · « **Reply #343 on:** 3 Jun 2016, 04:40 pm »

BRN - looks excellent

!

BRN · « **Reply #344 on:** 3 Jun 2016, 11:58 pm »

Quote from: lacro on 3 Jun 2016, 01:45 pm

Nice clean work, looks great No ventilation holes?

The 7297 chip was installed to the back of the chassis as described in the instructions. I attached the heatsink to the back of the chassis and applied thermal paste to help with the heat transfer. Should work fine to dissipate the heat.

Thanks for the nice comments. It was fun putting together.

Folsom · « **Reply #345 on:** 4 Jun 2016, 12:08 am »

The chip doesn't put out a lot of heat, but keeping it cools retains the power output. If it did run hot the heatsink would need to be rotated 90* to allow convection to work better.

My vent holes were because the heatsink is on the inside.

lacro · « **Reply #346 on:** 4 Jun 2016, 02:40 pm »

Quote from: Folsom on 4 Jun 2016, 12:08 am

The chip doesn't put out a lot of heat, but keeping it cools retains the power output. If it did run hot the heatsink would need to be rotated 90* to allow convection to work better.

My vent holes were because the heatsink is on the inside.

My case definitely needs vents as it can get warm, not from the chip which has an external heatsink (oriented correctly), but from the transistor heatsink which is internal. BRN's case is pretty large so maybe vents are not needed, but probably worth checking.

limits · « **Reply #347 on:** 9 Jun 2016, 10:36 pm »

Hi guys. Well. Amp board attempt number two. New board, all new parts. And...it works!! This time I heeded Folsom's advice, and took my time. Thank you VERY much for designing this, and making it available for others.

Seems to have a fair bit more gain than my tube amp...15 watts is plenty for my B1 buffer/Exodus Audio Kepler speakers. Really, really liking what I am hearing

Reported to have great mids on up, which it does. The thing that surprised me most was the bass, which is also excellent.

Will upload some pics of it in a bit--thought I could just do it directly from my phone, but can't get it to work...

Thanks again, Folsom!

Folsom · « **Reply #348 on:** 9 Jun 2016, 11:14 pm »

limits · « **Reply #349 on:** 10 Jun 2016, 03:08 pm »

Some shots of my Folsom 7297 amp. Didn't appreciate how dang big those caps were until I tried to fit them on the board...

lacro · « **Reply #350 on:** 10 Jun 2016, 08:42 pm »

Quote from: limits on 10 Jun 2016, 03:08 pm

Some shots of my Folsom 7297 amp. Didn't appreciate how dang big those caps were until I tried to fit them on the board...

Wow! Great work, that's a really nice looking build

It makes mine look so ghetto

What's up with the high end Jentzen caps, think they make a difference? Give it time to burn-in, it gets better with time. I never gave much credence to the theory of component burn-in except with speakers, but I think the Folsom amp really comes alive with some time on it. BTW, what's the rest of your nice looking system consist of?

limits · « **Reply #351 on:** 11 Jun 2016, 02:55 pm »

Hi lacro; Thanks--And I love the way your build turned out. In fact it was your posted pics that got me over the hump to try again with a second amp board.

Thanks also for the Tenma suggestion. Although the attempt to replace the chip on the first board proved unsuccessful, it made the process a lot easier.

I have no idea if the Jentzen caps make a difference, as I haven't heard another build. I have used them in the past for speakers, and liked them, so I figured what the heck...I am really liking the amp, tho...

My mess...uhh, I mean my test setup, to see if I finally have a working amp, consists of a Nelson Pass B1 buffer (in the repurposed wooden wine box), a Schiit Audio multibit Bifrost, which is awesome, an Oppo (bdp-83, I think), and Exodus Audio Kepler speakers, which I can't say enough good things about. They sound amazing for a 1/2 cu. ft. Vented box.

I will continue to let the amp settle in, and let you know how that progresses...can't imagine improvement from here, as what I am currently hearing is very nice, but if it happens, I'll take it...

BRN · « **Reply #352 on:** 11 Jun 2016, 04:24 pm »

Quote from: limits on 9 Jun 2016, 10:36 pm

Reported to have great mids on up, which it does. The thing that surprised me most was the bass, which is also excellent.

Limits,

I thought the same thing with the bass. Compared to my ZKIT1 the bass extension was much better and having the extra power is a nice plus.

When I put the amp together I was also thinking about putting in different input caps, but decided to go with the BOM on the build. Maybe I will change them out later with some boutique type.

I'm still in the process of letting the Folsom break-in. I only have about 30 hours on it. The changes so far have been subtle but noticeable. The mid-range is opening up nicely, and seems to be the biggest change.

This is the first amp I have had in about 11 years that does not use tubes and so far I'm happy with how it sounds, and the price is hard to beat.

limits · « **Reply #353 on:** 11 Jun 2016, 08:42 pm »

Hi BRN;

My congratulations on your build--Wow; very nice--appearance worthy of the sound

The Folsom 7297 amp to me sounds as 'tubey' as my tube amp (in the good way) without the hum. Oh, and was/is quite a bit cheaper, especially considering the re-tubing roller coaster

limits · « **Reply #354 on:** 12 Jun 2016, 06:39 pm »

Hi All:

I have been running my amp, letting it settle in this weekend. Ran it for most of the day yesterday, and again this afternoon.

I noticed the D45H11G with the suggested slip-on heatsink from Mouser gets HOT, like 'burn your finger when you touch it hot'. The 7297 chip/heatsink is just warm.

Is this similar to what you all are seeing, or is this unusual?

Thanks; All else seems normal, and it sounds great (this is using the Folsom antipole, btw)...

limits

limits · « **Reply #355 on:** 12 Jun 2016, 06:59 pm »

Ugh...I think I answered my own question. I installed the D45H11G BACKWARDS!!

I will shut things down, and take a look at the datasheet, but what a dumb a$$...Geez...

Assuming I will need to fix this...

Folsom · « **Reply #356 on:** 12 Jun 2016, 07:11 pm »

Ops. If you're finding it too hard to get it back into the holes, you can mounted it on the bottom sort of like an SMD device.

Don't feel bad, all of us didn't notice in your pics.

limits · « **Reply #357 on:** 12 Jun 2016, 07:46 pm »

Hi Jeremy; Can I do this now, or should I wait for the caps to discharge? Man, this build has been a humbling experience

Folsom · « **Reply #358 on:** 12 Jun 2016, 08:02 pm »

Discharged is best, or it could blow up the transistor. You can check their voltage to see if they have.

limits · « **Reply #359 on:** 12 Jun 2016, 09:03 pm »

Alrighty...fixed.

Surprised it worked before?

It sounds the same, and don't think the finger burner is any cooler, but at least it is oriented correctly. Used my other board's transistor after I cut the leads to the reversed one too short... Feel like the court jester. Oh well, ultimately this sounds great. Humbling? Yep. Hopefully entertaining to you all (...at least I didnt do THAT...)