Folsom's great little 7297 Chip Amp

lacro · « **Reply #140 on:** 10 Feb 2016, 12:15 am »

Hey Jeremy,
Can I use 20ga wire for power, and speakers if the lengths are just a few inches?

Ultralight · « **Reply #141 on:** 10 Feb 2016, 12:22 am »

Apologies. I've randomly scanned a few pages, including the first. I'm still a bit confused - is there a web page that explains exactly what is involved her ?

For example, what parts to order? How much for all the parts? And what type of work involved in soldering it?

And is this hands down better than the best of the breed in TPA3116 chip amps?

Sorry for the basic queries.

Thanks

Folsom · « **Reply #142 on:** 10 Feb 2016, 01:05 am »

Funny you mention it. I'm using a TPA3116 while my demo is out and about. It's a nice little budget amp. My TPA3116 has SEPF caps, my own PSU (that won out with many others on DIYaudio), and BlackGate N caps for input. It's not bad, but... I don't think it holds a candle to the TDA7297. ClassD is too soft if you ask me. It ultimately limits it a lot.

I'll PM you for $ and such.

JeffB · « **Reply #143 on:** 10 Feb 2016, 01:56 am »

I had assumed the 7297 was class D. What is the design?

Folsom · « **Reply #144 on:** 10 Feb 2016, 01:58 am »

AB , I'm not sure at what level it goes from A to AB.

Odal3 · « **Reply #145 on:** 10 Feb 2016, 06:30 am »

Parts finally ordered. Now I only need to get some decent wire and I will be ready to go.

Philistine · « **Reply #146 on:** 14 Feb 2016, 05:11 pm »

This is my first project, Amp and Antipole, and reasonably confident with the build.
I'm procrastinating at the moment because of finding the right case and heat sink combination - if anyone has any suggestions/recommendations it would be appreciated, or maybe a group buy?

I've got a few pairs of GR Research speakers, Neo 2's and Criterions, that I'm looking to fire up with the Chip Amp.

Folsom · « **Reply #147 on:** 14 Feb 2016, 08:29 pm »

I recommended some in the notes that I emailed. There's a number of enclosures on eBay as well.

chocoking_118 · « **Reply #148 on:** 15 Feb 2016, 03:25 pm »

Hi,
I am looking for a 6 channel amp for LXmini speakers where the recommended power is 50W per channel. Is this little amp powerful enough for the task? Appreciate your advice please.

Thanks.

Folsom · « **Reply #149 on:** 15 Feb 2016, 09:11 pm »

The sensitivity on those speakers is awfully low as raw drivers. Unless they get a healthy boost from the construction of their enclosures to 87+ then I would say no, I wouldn't do it. I prefer 91db+ but I still get a good time out of less.

hdspeakerman · « **Reply #150 on:** 15 Feb 2016, 09:43 pm »

Rane MA-6

Folsom · « **Reply #151 on:** 19 Feb 2016, 03:01 am »

This should be arriving in Indonesia some time soon along with a PSU, heatsink, and transformer. It's replacing a F5 that just makes too much heat.

Odal3 · « **Reply #152 on:** 19 Feb 2016, 03:18 am »

Got my desk full of small component bag packages. Just waiting for the final package. Hope to start putting it together this weekend

lacro · « **Reply #153 on:** 21 Feb 2016, 03:42 pm »

Quote from: Folsom on 19 Feb 2016, 03:01 am

This should be arriving in Indonesia some time soon along with a PSU, heatsink, and transformer. It's replacing a F5 that just makes too much heat.

It looks like you opted for a different heat sink from the clip-on one in the BOM. I was thinking of using one I pulled from an old PC to save me ordering the correct one separately. Also, does this heat sink need any mica/thermal paste, and hole bushing, or is it just bolted/clipped on with no insulation?

Another question, this one about the chip heat sink: Are you instructing that the mica sheet, and thermal paste be applied before installing the chip, tack solder the chip, and THEN removing the heat sink for final soldering of the chip? What happens to the thermal paste, does it need to be re-applied? Wouldn't it be better to assemble everything dry before applying the thermal paste? Confused

Please clarify....

Folsom · « **Reply #154 on:** 21 Feb 2016, 05:29 pm »

No need for insulation on the transistor heatsink. But don't let it touch other parts like the two resistors below it. I used that heatsink because I had it, and wanted to not wait on another package.

Why would you use thermal paste during the fitting process on the chip? I don't follow. The only place I'd consider using before final mounting of chip is wiping it on and off the heatsink because the mica might stay in place on it without you needing to hold it if you wiggle it into place. So you really are dry fitting the chip.

mlundy57 · « **Reply #155 on:** 21 Feb 2016, 05:30 pm »

This is going to be my first attempt at building out a PC board. I have some experience with point to point wiring crossover networks but not with boards.

What tools, other than a soldering iron, do I need and/or would be very helpful for building the amp and Antipole?

Mike

Folsom · « **Reply #156 on:** 21 Feb 2016, 06:48 pm »

I like a little worklight. Also useful is one of these for cleaning the tip of the soldering iron. For solder I recommend something sized for electronics and not speakers. I've been using Kester 44, the same roll, for years (the label on mine is ancient and unreadable) But you could spring for some Cardas solder too, if you want. Lastly a fine tip is needed. The big fatties won't work!

The most important thing is patients. Make sure the spot is heated so the solder forms on the vias hole on the PCB board as well as the component. If the component got pretty warm during the process start on another one and come back to it. Sometimes on the Antipole it may be easier to do the little EPCOS caps from the top.

Soldering heat for the amp board is pretty standard, approximately 750-775F/400-412C. For the Antipole board with the snap caps and CMC you can run hotter, like 850F/454C, but make very sure you're contacting the PCB board and not just the component. This is all pretty standard stuff.

lacro · « **Reply #157 on:** 21 Feb 2016, 07:41 pm »

Quote from: Folsom on 21 Feb 2016, 05:29 pm

Why would you use thermal paste during the fitting process on the chip? I don't follow.

Sorry - I guess I misinterpreted your instructions below:

On the chip it needs to be thicker, you can wiggle the chip until it pushes it as close as it’ll get, you can check to make sure you got coverage once you remove it, a few steps down in this guide.

Then I finished soldering it after removing it from the heatsink and chassis, with PCB board.

Folsom · « **Reply #158 on:** 21 Feb 2016, 08:19 pm »

Yes perhaps I'll go back over that area. I updated it.

Honestly it's hard to go wrong so long as you have decent coverage, the thermal paste isn't super thick, and the chip is flat onto the mica. I thought the real trick was making sure the chip tab and bolt don't touch so you have good isolation. In fact if anyone has way too much trouble with that I have a work around where you drill a little oversized hole into the heatsink a 1-2mm and use a different shoulder washer that extends just past the chip tab.

mlundy57 · « **Reply #159 on:** 21 Feb 2016, 08:20 pm »

Quote from: Folsom on 21 Feb 2016, 06:48 pm

I like a little worklight. Also useful is one of these for cleaning the tip of the soldering iron. For solder I recommend something sized for electronics and not speakers. I've been using Kester 44, the same roll, for years (the label on mine is ancient and unreadable) But you could spring for some Cardas solder too, if you want. Lastly a fine tip is needed. The big fatties won't work!

The most important thing is patients. Make sure the spot is heated so the solder forms on the vias hole on the PCB board as well as the component. If the component got pretty warm during the process start on another one and come back to it. Sometimes on the Antipole it may be easier to do the little EPCOS caps from the top.

Soldering heat for the amp board is pretty standard, approximately 750-775F/400-412C. For the Antipole board with the snap caps and CMC you can run hotter, like 850F/454C, but make very sure you're contacting the PCB board and not just the component. This is all pretty standard stuff.

Thanks

I have an Ottlite desk lamp but was thinking of getting an LED light with a magnifying lens. Any suggestions as to a good one or what power magnification works best?

My soldering iron is a 25W Radio Shack Pro-Line with a point tip and a maximum heat output of 1003F (539C). That's a lot hotter than you are suggesting. Looks like a different iron may be in order.

For solder I use Cardas Quad Eutectic

I have one of the small black helping hands with the alligator clips but I am not fond of it. Any other suggestions for something to hold the board while working on it?

Mike