Folsom's great little 7297 Chip Amp

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lacro

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Re: Folsom's great little 7297 Chip Amp
« Reply #920 on: 6 Oct 2017, 05:54 pm »
On one of the amp boards I built, I inadvertently swapped polarity on the power inputs which immediately fried the chip. You didn't possibly do that did you? Another thought: could a static discharge from you handling the chip or from your soldering iron have zapped the chip? If you have to go that route, the chip is only $4 but kind of a pain to remove. I cut all the leads from the chip, and desoldered them one at a time which wasn't that difficult. Hope you solve your problem soon.

undertowogt1

Re: Folsom's great little 7297 Chip Amp
« Reply #921 on: 6 Oct 2017, 06:45 pm »
On one of the amp boards I built, I inadvertently swapped polarity on the power inputs which immediately fried the chip. You didn't possibly do that did you? Another thought: could a static discharge from you handling the chip or from your soldering iron have zapped the chip? If you have to go that route, the chip is only $4 but kind of a pain to remove. I cut all the leads from the chip, and desoldered them one at a time which wasn't that difficult. Hope you solve your problem soon.

thanks for your thought. I did not have the polarities wrong at any time from the PSU to the AMP Board so that would not fry the chip. Maybe a static discharge, but I really dont know. All I can conclude is that the chip is broken.  maybe I will desolder in redo it to see what happens.

Odal3

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Re: Folsom's great little 7297 Chip Amp
« Reply #922 on: 6 Oct 2017, 07:21 pm »
Quote
Any other recommendations. What would an experienced AMP makers next move be.

I'm far from an experienced AMP maker and would put myself at the other side of the spectrum...so pay more attention to the experts. The only thing I would add is before going through the painful process of desoldering is to make sure to triple check the obvious. For example, when I built my amp board I spent an evening trouble shooting why I didn't get any sound - in the end it turned out to be a faulty RCA cable... :duh:

It's probably not what you have problem with, but at least a lesson I learned is to always make sure to check the easy things first. Hope you will get it sorted soon!

Folsom

Re: Folsom's great little 7297 Chip Amp
« Reply #923 on: 6 Oct 2017, 07:28 pm »
Odal, that is pricesly why I said going insane and doing something unnecessary is part of the standard process.

Odal3

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Re: Folsom's great little 7297 Chip Amp
« Reply #924 on: 6 Oct 2017, 08:18 pm »
 :lol:

undertowogt1

Re: Folsom's great little 7297 Chip Amp
« Reply #925 on: 7 Oct 2017, 04:07 am »
Is there any way to test the transistor with multi meter. The transistor that can be fried if the PSU is plugged in if the capacitors are charged. I don't think I did that but I want to be positive I didn't.

Folsom

Re: Folsom's great little 7297 Chip Amp
« Reply #926 on: 7 Oct 2017, 05:09 am »
Only if you take it out first.

undertowogt1

Re: Folsom's great little 7297 Chip Amp
« Reply #927 on: 7 Oct 2017, 01:33 pm »
Ok I will take it out. Am I then just checking continuity between the legs.................EDIT> I contacted my Father In Law and apparently Transistors are I little more complicate to test
« Last Edit: 7 Oct 2017, 04:06 pm by undertowogt1 »

undertowogt1

Re: Folsom's great little 7297 Chip Amp
« Reply #928 on: 7 Oct 2017, 04:41 pm »
Oh my Gosh :o, I am on my way to solving this. Something silly of course , its working will update when it is 100 percent :icon_lol:

UPDATE: So it has something to do with the binding post. When I was trouble shooting I tested continuity from inputs to the board and from the board outputs to the binding post, ALL was good. Also when trouble shooting I attached my speaker wire directly to the output wire, BUT the output wire was ALSO attached to the binding post at the same time. When I finally solved the issue I de soldered the binding post and went direct to Speaker wire.  Bingo, it worked. I didnt a little dance and ran around the house telling everyone I think I solved it. The were like......oh.

So I guess the binding post were shorting out the single somehow. I need to figure that out now. Currently listen direct from the outputs and it sounds great so far.




UPDATE: Since I am such a newbie at this I made s silly mistake. Hopefully another newbie can learn from it reading this thread. When I drilled the binding post holes I did them to the size of the binding post  POST. So my Binding post were touching the chassis The were shorting out the binding post. So even when I was trouble shooting it was shorting out my signal.
« Last Edit: 7 Oct 2017, 10:35 pm by undertowogt1 »

uncola

Re: Folsom's great little 7297 Chip Amp
« Reply #929 on: 7 Oct 2017, 06:38 pm »
Congrats undertow!  You’re the second person in this thread where it turned out his problem was the binding posts..  odd

undertowogt1

Re: Folsom's great little 7297 Chip Amp
« Reply #930 on: 8 Oct 2017, 01:32 am »
Finished and working, so far it sounds better than my other AMP, Yamaha CR1020. The build was pretty easy for a newbie like me until I ran into my rough patch after it didn't work :lol:. Ultimately it was a simple, silly issue with a simple fix. Thank you Jeremy and others on the forum for their time and help with my built. I am very happy with it.





« Last Edit: 8 Oct 2017, 03:30 am by undertowogt1 »

S Clark

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Re: Folsom's great little 7297 Chip Amp
« Reply #931 on: 8 Oct 2017, 01:40 am »
Glad you got it working.  They are very high quality amps if a dozen watts will suffice- and for not much cash. 
Mine does a great job with 91 dB efficient speakers.   

BRN

Re: Folsom's great little 7297 Chip Amp
« Reply #932 on: 8 Oct 2017, 01:59 pm »
Glad you were able to figure out the problem. I think we have all had to deal with making mistakes when doing diy, I know I’ve had my share.

It is a great sounding amp. I really enjoy mine and have plans to put another one together.

By the way, what are you using to separate the sections between the transformer, power supply, and amp?

lacro

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Re: Folsom's great little 7297 Chip Amp
« Reply #933 on: 8 Oct 2017, 02:24 pm »
Glad you got it solved. This seems to be a common mistake. See my comment at post 696 http://www.audiocircle.com/index.php?topic=138229.msg1565604#msg1565604
The holes drilled in the chassis have to be the diameter of the step on the plastic washer which prevents the post from shorting to chassis. The common mistake is to drill the holes the size of the threaded post which can allow it to contact the chassis. See the drawing in the link I posted in the above post.

undertowogt1

Re: Folsom's great little 7297 Chip Amp
« Reply #934 on: 8 Oct 2017, 03:33 pm »
Quote

By the way, what are you using to separate the sections between the transformer, power supply, and amp?


Between the amp and psu and transformer I am using some metal I had kicking around. It was perfect because it was already bent at the bottom for mounting. I painted it a funky yellow and drilled holes to accommodate and mount MDF on each side. I wanted to dampen the metal walls and it worked out well. The MDF made everything a little more solid for mounting.

undertowogt1

Re: Folsom's great little 7297 Chip Amp
« Reply #935 on: 8 Oct 2017, 04:32 pm »

The holes drilled in the chassis have to be the diameter of the step on the plastic washer which prevents the post from shorting to chassis. The common mistake is to drill the holes the size of the threaded post which can allow it to contact the chassis. See the drawing in the link I posted in the above post.

Ya this is exactly what I did. The holes I drilled initially where the size of the threaded pole. It all made sense once I figured it out. Rookie mistake right :thumb:

Folsom

Re: Folsom's great little 7297 Chip Amp
« Reply #936 on: 8 Oct 2017, 06:40 pm »
I did actually mention to check for that.

Many binding posts have a tiny lip to prevent it, easy to miss.

limits

Re: Folsom's great little 7297 Chip Amp
« Reply #937 on: 8 Oct 2017, 08:24 pm »
Nice, undertowogt1!! :thumb: Am glad you got it working! Enjoy!

undertowogt1

Re: Folsom's great little 7297 Chip Amp
« Reply #938 on: 8 Oct 2017, 11:25 pm »
I did actually mention to check for that

Yes Folsom, I remember. I am too inexperience and only checked for continuity between the board and binding posts. I am learning as I go with my multi meter as well. I learned a lot of basic things with this build.

absolutk

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Re: Folsom's great little 7297 Chip Amp
« Reply #939 on: 10 Oct 2017, 03:03 am »
I'm relieved that the issue is resolved, undertowogt1! You will not be disappointed in what you hear.

TL;DR: This amplifier is incredible... IF your speakers are not insanely hard to drive. If you've been debating, do it now.

I've traveled quite a bit in my audio journey, and practically all of it has been in the same apartment. I've had a Parasound A21, Simaudio i5.3, Vinnie Rossi LIO, and Devialet 400 among solid state equipment (a handful of tube gear here and there), paired over the years with Zu Superfly, Harbeth C7, Martin Logan Vantage, and finally tired of the constant chase, a locally made pair of speakers using Focal drivers which are basically illiquid.

I'd bought Jeremy's boards (DIY7297 + Antipole) a while ago, but never got around to ordering the parts because life got in the way, and the Devialet combination was working so well. Still there were some quirks, and I always thought that I could eliminate those with a raspberry pi. So I finally bit the bullet and ordered the standard BOM from Mouser, a DAC from the good guys at Allo, a chassis off of Amazon and connectors and wire from around the web. I expected assembly to take the whole weekend, but put it all together in four hours! The chassis was being a bit troublesome but finally hooked it all up, got Spotify Connect working and... sound!

And not just sound - a sound that got me close enough to the Devialets to make me sell them.

Here are the characteristics that stand out the most:

* Impeccable control on the sub-100 Hz range
* I'm not sure if I'm using this correctly, but the 'dynamic range' is fantastic. Its ability to deliver a bass punch to the gut and simultaneously rustling leaves in your ears is pretty neat.
* The background is black as ink. Though, when I get closer there's a mild 120 Hz hum that I need to trace down.
* The soundstage was wide when I used the standard Kemet + Vishay caps in the input stage. When I replaced those with Jantzen Superior, it became W I D E. The Jantzen took about 3-4 days to break in.
* Micro details/voice texture could be more pronounced, but then again, the entire source is <$150, so that's likely the bottleneck

This weekend I took the amp to my friend's place who also has a Devialet 400, but with a pair of Magico Q1 (4~5 Ohms, 86 dB/w/m). Listening to it at medium volume (baby was sleeping), we couldn't hear any bass from 5-6 ft away. Swapped back to the Devialet and more music seemed to emanate at the same listening level. My speakers are supposedly 91 db/w/m sensitive, and simply rock at all volumes.

The boards are really thoughtfully laid out and their quality is fantastic. As you can see, Jeremy is enthusiastic about helping and teaching. Super kudos to him. This is a wonderful and simple opportunity for one to create something of beauty *and* value.

Thankfully he had a few more boards remaining from the last run and I managed to get another 2x DIY7297 + Antipole boards from him. I'm considering a dual mono design. I really have no reason to do so apart from curiosity. Does anyone have thoughts on how to approach bridging? I have 3 pairs of binding posts on each speaker (2 in the bookshelf, 1 in the LFE), if that affects the direction.

 






« Last Edit: 10 Oct 2017, 05:15 am by absolutk »