Folsom's great little 7297 Chip Amp

rockdrummer · « **Reply #1080 on:** 13 Feb 2019, 04:53 pm »

Great! Just what I needed to hear.
Thanks,
Ben

RoadTripper · « **Reply #1081 on:** 13 Feb 2019, 05:24 pm »

I've read through this valuable thread and I came to the clear realization that there are several items that are needed to finish the job that are not listed in the BOM. This is what I have so far:

1. Anti vibration pads/material
2. Enclosure
3. Transformer
4. Wire
5. Switch
6. LED
7. Rubber washers
8. Thermal grease
9. Rubber standoffs
10. IEC connector - fuse

Can anyone add to this list? I suspect it isn't complete.

Folsom · « **Reply #1082 on:** 13 Feb 2019, 07:34 pm »

There is a transformer on the BOM, but maybe it's out of stock?

RoadTripper · « **Reply #1083 on:** 14 Feb 2019, 04:19 pm »

I must be dense. I don't see a transformer on the BOM. What's its part number?

bentconvert · « **Reply #1084 on:** 14 Feb 2019, 07:24 pm »

Mouser #546-185F16 Hammond #185F16 Hammond Power Transformers Global/Chassis Mount 130VA, 16V CT @8.1A

Folsom · « **Reply #1085 on:** 14 Feb 2019, 07:58 pm »

Quote from: bentconvert on 14 Feb 2019, 07:24 pm

Mouser #546-185F16 Hammond #185F16 Hammond Power Transformers Global/Chassis Mount 130VA, 16V CT @8.1A

Yes, it's in the upload file.

RoadTripper · « **Reply #1086 on:** 14 Feb 2019, 08:17 pm »

Ah. There it is in the Antipole BOM. I was looking in the wrong one.

So, back to my question, then, is my list of parts/items incomplete?

lacro · « **Reply #1087 on:** 14 Feb 2019, 08:34 pm »

Quote from: RoadTripper on 13 Feb 2019, 05:24 pm

I've read through this valuable thread and I came to the clear realization that there are several items that are needed to finish the job that are not listed in the BOM. This is what I have so far:

1. Anti vibration pads/material
2. Enclosure
3. Transformer
4. Wire
5. Switch
6. LED
7. Rubber washers
8. Thermal grease
9. Rubber standoffs
10. IEC connector - fuse

Can anyone add to this list? I suspect it isn't complete.

Board stand offs.
Automatic center punch for marking holes in aluminum.
Step drill for drilling holes in aluminum.
Hand counter sink tool with handle for deburring drilled holes.
T-handle reamer for enlarging holes (not essential, but handy)

Folsom · « **Reply #1088 on:** 14 Feb 2019, 09:48 pm »

The BOMs are for board population only, and transformer. The rest is up to you, but I did note lots of possible things in the notes.

borism · « **Reply #1089 on:** 18 Feb 2019, 03:45 pm »

Hi Jeremy,
I received my boards and am waiting for the various ordered components to arrive before starting my build. One question I have is about the input capacitors. My understanding is that a 1.5 uf capacitor or higher helps extend the lower frequency. The film bypass cap is 0.022 uf. What is the function and what effect would a slightly higher 0.056 - 0.1 uf rating as bypass have? I am asking because I have a few high quality 0.056 and 0.1 uf film caps from prior projects.
Thanks

Folsom · « **Reply #1090 on:** 18 Feb 2019, 07:07 pm »

They'll do basically the same thing. They just cost more so I didn't spec them as getting bigger with the bypass doesn't benefit you really. But if you have them, use them! You can also not use bypass cap, totally up to you. The input caps are a fun place to explore differences, you just need 1.5uf (total) or more is the only requirement.

mzbrahce · « **Reply #1091 on:** 22 Feb 2019, 03:07 pm »

Hi Jeremy--

I'm finally in the process of completing my 7297 and have a few questions. I have decided that I need 3 inputs, so I am planning to add a rotary switch. I'm also using the 10K DACT. Should the switch come after the DACT or before it? I also want to use headphones with it. What is the best way to do that? Just use a 3x switching jack? https://www.mouser.com/Connectors/Audio-Video-Connectors/Phone-Connectors/_/N-778cv?P=1yzvc3fZ1z0yy6bZ1yvsm2eZ1yzvpvdZ1yzowym

Thanks for all of this! It is a lot of fun building this out, and I'm looking forward to countless hours of great sounds.

------------------Mark

Folsom · « **Reply #1092 on:** 22 Feb 2019, 05:12 pm »

I would go before.

I wouldn't use this amp to power headphones. If you did try it, you need headphones that can accept 4 wire, balanced output (and a bunch of resistance probably to get the power down, on separate switched outputs)

mzbrahce · « **Reply #1093 on:** 22 Feb 2019, 06:23 pm »

Thanks for the quick response.
I'll get a separate headphone amp.

lacro · « **Reply #1094 on:** 22 Feb 2019, 06:29 pm »

I don't get it, How does the DACT go before the input selector? Please explain. I put the DACT on the output of the selector.

Folsom · « **Reply #1095 on:** 22 Feb 2019, 07:22 pm »

I meant selector before DACT.

WireNut · « **Reply #1096 on:** 22 Feb 2019, 08:33 pm »

Hi lacro,

This looks interesting. Can you tell me how it hooks up?
If I only have 1 input on an existing preamp will this add more inputs?

What are the rear RCA's, inputs/outputs?
Why 2 dials?

Quote from: lacro on 22 Feb 2019, 06:29 pm

I don't get it, How does the DACT go before the input selector? Please explain. I put the DACT on the output of the selector.

lacro · « **Reply #1097 on:** 22 Feb 2019, 09:10 pm »

It's a Glassware audio 3 input selector with one output. Yes it would allow you to have multiple inputs to your preamp. The reason for the 2 knobs is one is for the selector, and the other is the DACT volume control. I originally made it as an input selector, but recently added the DACT pot making it a great sounding passive preamp with 3 inputs. If i did it again, I would add one more output for a powered sub.

https://glass-ware.stores.yahoo.net/inseswandpcb.html

lacro · « **Reply #1098 on:** 22 Feb 2019, 09:18 pm »

Also, check out this thread for more options: https://www.audiocircle.com/index.php?topic=161437.180

borism · « **Reply #1099 on:** 15 Mar 2019, 12:44 am »

It's alive! Sounds very nice on initial listen.