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May 15, 2021, 04:33:11 PM

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21
Amplifier Discussion / Re: Output transformer for Class D Amp?
« Last post by Jazz P Bass on May 05, 2021, 11:41:09 AM »
I would ditch the idea.
The transformer will not do anything to affect or color the sound.
In fact, you may be causing issues with the module.
22
Amplifier Discussion / Output transformer for Class D Amp?
« Last post by Stephenl on May 05, 2021, 08:20:38 AM »
I have a B&O ICEpower 200ASC that I was thinking about using for the output of a guitar amplifier.

I also have a 500VA Hammond toroid power transformer 120/240:120/240... I'd wire it 1:1.

The purpose would be to maybe "warm up" the sound a bit.

Am I asking for trouble / bad idea?
23
The Newcomer's Forum / Re: 739 AND 5558 IC CROSSREFERENCE
« Last post by TJEsmooth61 on May 04, 2021, 09:33:39 PM »
Ok.. just joind your forum to answer this question
Ua739 has a few replacement :-
Ua749 .. does not have same audio db filter but will work
MC1303L direct equivalent
RC4739 direct equivalent

you can also make / use an RC4558 with small surface mount chip adaptor to suit 14pin dip
24
Amplifier Discussion / Re: Thunderfunk with Dead Power Amp Board
« Last post by joecool85 on May 04, 2021, 11:50:47 AM »
Like most of these modules, the output is balanced. That means you can't ground one side, and you shouldn't use phone type plugs because there will be dangerous Voltages on the metal shells.

There is no good way to drop Voltages to what you need. You can burn several hundred watts via analog means, or build a switching regulator :(

Good points, and all the more reason to not use 1/4" jacks for speaker connections.  Time to use Speakon connectors.  It's been 25+ years, time for the industry to transition!

Regarding the voltages, you could use a DC/DC converter, but honestly I would just build out a new PSU for the power amp.  Leave the existing for the preamp if you'd like though.

**edit**
I just looked at the datasheet you shared.  The +/-12v is for input voltage, IE signal.  Your preamp will provide that without issue I would guess.  You do need about 75v DC for the PSU though.  Looking at Parts Express, it seems that the board you linked is for use only to add on to another "ICE" board.  They recommend using this one with it's built in PSU for $312 USD: https://www.parts-express.com/ICEpower-500ASP-Class-D-Audio-Amplifier-with-Power-Supply-Module-1-x-500W-326-204
25
Amplifier Discussion / Re: Chipamp kit LM1875 PDF?
« Last post by joecool85 on May 04, 2021, 11:44:45 AM »
Hey everyone. I was a member here way back when this forum began and was lucky enough to receive a couple of chipamp.com kits from Brian and this site. The LM3886 and the stereo LM1875.

I assembled the LM3886 kit but never got around to testing it because I couldn't afford the transformer and never assembled the LM1875 kit. Found them the other day and would love to finish them up. The LM3886 I reversed engineered it but would still like to check. The LM1875 I have no reference for.

If anybody has the PDF of the instructions that isn't a dead link I would much appreciate it.

Cheers

Here you go: https://www.ssguitar.com/index.php?topic=5031.0
26
Schematics and Layouts / Chipamp.com schematics and manuals
« Last post by joecool85 on May 04, 2021, 11:44:22 AM »
I've had a few people ask about these so I figured I would share them.  Attached are the manuals (with schematics) for the LM1875 and LM3886 kits BrianGT sold at Chipamp.com for a long time.
27
Amplifier Discussion / Chipamp kit LM1875 PDF?
« Last post by Bottlewater on May 04, 2021, 01:09:55 AM »
Hey everyone. I was a member here way back when this forum began and was lucky enough to receive a couple of chipamp.com kits from Brian and this site. The LM3886 and the stereo LM1875.

I assembled the LM3886 kit but never got around to testing it because I couldn't afford the transformer and never assembled the LM1875 kit. Found them the other day and would love to finish them up. The LM3886 I reversed engineered it but would still like to check. The LM1875 I have no reference for.

If anybody has the PDF of the instructions that isn't a dead link I would much appreciate it.

Cheers
28
Honey Amp / Re: Got my kit!
« Last post by joecool85 on May 03, 2021, 09:07:52 PM »
I checked my box and it does look like I'm missing the sticker as well. I'll message you on Kickstarter. Thanks!

Sounds good, I'll get a sticker out to you.  Enjoy the kit!
29
Honey Amp / Re: Got my kit!
« Last post by joecool85 on May 03, 2021, 09:07:11 PM »
I received mine today, and the box was smashed almost flat, split open on both ends, and had stickers that said "RECEIVED DAMAGED".  Apparently the only thing lost were any stickers, since I checked all components and they were all accounted for.  I would like a sticker!

I did not understand the note on the schematic that reads "For gain circuit, do not populate R0 and C0".

Phil from gorgeous Young Harris, Georgia, USA

The gain circuit is the standard circuit.  You can use the modifications listed in the notes to have a buffer in front rather than a gain circuit.  I think I may take these notes off the schematic to avoid confusion...though I do want to say something about R0 and C0 so folks know they can leave them empty for a stock config.  I'll come up with something.

Regarding the sticker, I'll get it sent out to you.  Glad the damaged box still had everything in it!
30
Amplifier Discussion / Re: Thunderfunk with Dead Power Amp Board
« Last post by pizzafrenchfry on May 03, 2021, 07:29:04 PM »
Like most of these modules, the output is balanced. That means you can't ground one side, and you shouldn't use phone type plugs because there will be dangerous Voltages on the metal shells.

There is no good way to drop Voltages to what you need. You can burn several hundred watts via analog means, or build a switching regulator :(

Good point, that would be a big drawback. I've heard these ICE units are used in several commercial bass amps. I wonder how it's implemented.

I was considering using something like the MOSFET voltage reducer attached. There is a large heatsink in the chassis already and a fan. Would require a large power mosfet in the several hundred+ watt range, but I believe this would work.
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