Folsom's great little 7297 Chip Amp

rockdrummer · « **Reply #1180 on:** 27 Apr 2019, 08:23 pm »

Okay, what does that mean? I'm lost.
I want more than 20v?

rockdrummer · « **Reply #1181 on:** 27 Apr 2019, 08:36 pm »

Undertowogt1 is also using one on page 47.

Not sure what to do now. I will wire this up, see if it sounds okay. I will eventually be using servo subs on both sides and amps for bass, but I certainly want the best out of this amp.

Folsom · « **Reply #1182 on:** 27 Apr 2019, 08:41 pm »

Give it a try. What sensitivity are the speakers?

rockdrummer · « **Reply #1183 on:** 27 Apr 2019, 08:47 pm »

91db. Today, my test speakers are definitive technology bp8. I will hopefully have some open baffle monitors around 93 db in the next couple months.

Folsom · « **Reply #1184 on:** 27 Apr 2019, 09:07 pm »

Give it go. You can swap transformers later.

WireNut · « **Reply #1185 on:** 27 Apr 2019, 10:06 pm »

Quote from: Folsom on 8 Apr 2019, 01:27 am

Add the slots between the speaker binding posts, and the RCA posts.

I'm late to this thread. Please help me understand "Add the slots between the speaker binding posts, and the RCA posts."

zek · « **Reply #1186 on:** 27 Apr 2019, 10:45 pm »

Quote from: WireNut on 27 Apr 2019, 10:06 pm

I'm late to this thread. Please help me understand "Add the slots between the speaker binding posts, and the RCA posts."

See two pages back.

https://www.audiocircle.com/image.php?id=193206

WireNut · « **Reply #1187 on:** 27 Apr 2019, 10:53 pm »

Quote from: zek on 27 Apr 2019, 10:45 pm

See two pages back.
https://www.audiocircle.com/image.php?id=193206

I see that It's a thru slot between the RCA's and also the binding post. But Y, what does it accomplish?

Is it to separate the grounds?

rockdrummer · « **Reply #1188 on:** 27 Apr 2019, 10:54 pm »

Alright. Bountiful sound out of the left channel, and no right channel. Both interconnects work into the left channel, but not the right. Also, the right speaker works out of the left binding post. So it's either the right rca input or somewhere between it and the right binding post.

WireNut · « **Reply #1189 on:** 27 Apr 2019, 11:20 pm »

Quote from: Folsom on 8 Apr 2019, 01:27 am

Add the slots between the speaker binding posts, and the RCA posts.

Quote from: Peter J on 8 Apr 2019, 01:37 am

Will do. I'll post CAD file once done that will show more detail, including slots. Slots between RCAs as well, huh?

Quote from: Folsom on 8 Apr 2019, 01:44 am

YES. The grounds on the RCA sockets need to be able to "see" each other electrically. The results are very nice.

Got It

WireNut · « **Reply #1190 on:** 27 Apr 2019, 11:22 pm »

Quote from: rockdrummer on 27 Apr 2019, 10:54 pm

Alright. Bountiful sound out of the left channel, and no right channel. Both interconnects work into the left channel, but not the right. Also, the right speaker works out of the left binding post. So it's either the right rca input or somewhere between it and the right binding post.

rockdrummer needs help.

rockdrummer · « **Reply #1191 on:** 27 Apr 2019, 11:53 pm »

GOT IT!

I gave the heatsink attached to the chip a tiny bit of a wiggle, and the right channel flickered. Reflowed all the chip tabs and I'm making music!

Thanks wirenut, I'm good now.
Ben

rockdrummer · « **Reply #1192 on:** 28 Apr 2019, 12:15 am »

Going to dinner, mostly to celebrate! Haha

Then put the top on and do some burning in. I got 16.07v at the psu input.

Thanks for the help everyone.
Ben

undertowogt1 · « **Reply #1193 on:** 28 Apr 2019, 12:58 am »

Quote from: Folsom on 27 Apr 2019, 08:17 pm

15v will turn on but bass and gumption in general may be a bit (or lot) more limited.

Rockdrummer is correct, I did use a AS 1215. Should I be swapping it out for a AS 1218? The amp sounds really nice to my ears, am I missing out? I am getting 16 V AC on the Input of the PSU and 20.5 out of the PSU to the Aamp Board.

Folsom · « **Reply #1194 on:** 28 Apr 2019, 01:27 am »

With your speakers you may not notice. But it's an easy and fairly inexpensive thing you can try if you get the itch.

lacro · « **Reply #1195 on:** 28 Apr 2019, 03:00 pm »

Folsom:

If undertowogt1 is getting 20.5V out of the Antipole PS without load what happens when the volume is cranked, and the current load increases (voltage drops)? Is there enough voltage to activate the infinite capacitor?

From your original Indiegogo info about this amp:

-*Requires 21-25v to operate correctly, which is regulated down to 17.8-18v by Kmultiplier to meet amplifier chip voltage safety. This can be attained with batteries, SMPS, or to match the performance of the demo the Antipole also by Folsom.

From your post#4:

Yup, the "infinite capacitor" only activates with enough voltage (listed on my IndieGoGo). S Clark is going to get a very nice improvement soon switching to 24v input (gets regulated to 17.8-18v on amplifier board).

This AS1215 transformer chart shows the output voltage drop as load increases:

My question: If current load is decreasing the the transformer output voltage, does this have a detrimental affect on the chip when using the AS1215 transformer?

Folsom · « **Reply #1196 on:** 28 Apr 2019, 05:15 pm »

Voltage does drop, and I just don't know if it can maintain the infinite capacitor, I suspect not but I'd have to be on his power testing it. It's cutting it so close that I would just say "I doubt it".

I prefer above 21v for a transformer. SMPS doesn't waver so down to 21v on them is just fine.

S. Clark was on 12v before switching to 24v battery.

lacro · « **Reply #1197 on:** 28 Apr 2019, 07:24 pm »

Quote from: Peter J on 15 Apr 2019, 06:44 pm

Bulkhead complete. Time to get it Lacro-ized!

It has now been "lacro-ized" It fired right up first try, and it sounds great!

S Clark · « **Reply #1198 on:** 28 Apr 2019, 07:38 pm »

Quote from: Folsom on 28 Apr 2019, 05:15 pm

Voltage does drop, and I just don't know if it can maintain the infinite capacitor, I suspect not but I'd have to be on his power testing it. It's cutting it so close that I would just say "I doubt it".

I prefer above 21v for a transformer. SMPS doesn't waver so down to 21v on them is just fine.

S. Clark was on 12v before switching to 24v battery.

Only for a short while, until using a variable power supply up to 18V.
But 24V has clearly been a better option.

Peter J · « **Reply #1199 on:** 29 Apr 2019, 02:43 pm »

Quote from: lacro on 28 Apr 2019, 07:24 pm

It has now been "lacro-ized" It fired right up first try, and it sounds great!

I'd say lacro is being a little modest here, this compact and clean layout was mostly his brainchild. Between us, we managed to put "twelve pounds of potatoes in a ten pound sack".

While doing this he also checked fit for most recent amp board which I understand is longer. It would indeed fit, but I'll let him speak to the details should someone else decide to use this particular case.

Should be plenty of heat sinking there, no?