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9 Channel 3E Audio Amp(s) project

activewire

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My new amp modules just arrived! I will soon (after a 2 week trip) start building these into my home theater system - an Onkyo RZ50 in 5.2.4 configuration. This build is actually 2 separate but identically looking amps:

- a chassis containing (3) mono amp modules powered by Mornsun LOF750-20B48 (this is still in transit) that will drive my L/C/R front sound stage
- a second chassis containing (3) stereo amp modules again powered by a LOF750-20B48 to drive my rear surround pair and 4 atmos height speakers

These modules are the Rev B Jan 2024 with the extra 12 volt header, Nichicon caps, 1656 op amps and I must say the build quality is simply outstanding. Hard to believe the power to size ratio of these Class D modules, with sound quality measurements surpassing my 80 pound McIntosh MC7300 beast.

Because my AVR (like every AVR costing under $5K) has only RCA outputs, I must perform surgical mods on each module - solder on an SMD OpAmp, remove 2 resistors, and bridge one jumper. That will be so much fun ... times 9. Yet this still seems like a better solution (SQ and power wise) than RCA-to-XLR adapter cables, but feel free anyone who can talk me out of it.

Also in this pic is an older 4-channel 3E amp module from a different project and I've been extremely happy with! Will keep you posted on my progress, as more parts arrive and I get going on the build.
IMG_6096.jpg
 
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Guddu

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My new amp modules just arrived! I will soon (after a 2 week trip) start building these into my home theater system - an Onkyo RZ50 in 5.4.2 configuration. This build is actually 2 separate but identically looking amps:

- a chassis containing (3) mono amp modules powered by Mornsun LOF750-20B48 (this is still in transit) that will drive my L/C/R front sound stage
- a second chassis containing (3) stereo amp modules again powered by a LOF750-20B48 to drive my rear surround pair and 4 atmos height speakers

These modules are the Rev B Jan 2024 with the extra 12 volt header, Nichicon caps, 1656 op amps and I must say the build quality is simply outstanding. Hard to believe the power to size ratio of these Class D modules, with sound quality measurements surpassing my 80 pound McIntosh MC7300 beast.

Because my AVR (like every AVR costing under $5K) has only RCA outputs, I must perform surgical mods on each module - solder on an SMD OpAmp, remove 2 resistors, and bridge one jumper. That will be so much fun ... times 9. Yet this still seems like a better solution (SQ and power wise) than RCA-to-XLR adapter cables, but feel free anyone who can talk me out of it.

Also in this pic is an older 4-channel 3E amp module from a different project and I've been extremely happy with! Will keep you posted on my progress, as more parts arrive and I get going on the build.
View attachment 364352
All the best.

A few pictures as you progress would be great addition here!
 

MCH

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My new amp modules just arrived! I will soon (after a 2 week trip) start building these into my home theater system - an Onkyo RZ50 in 5.4.2 configuration. This build is actually 2 separate but identically looking amps:

- a chassis containing (3) mono amp modules powered by Mornsun LOF750-20B48 (this is still in transit) that will drive my L/C/R front sound stage
- a second chassis containing (3) stereo amp modules again powered by a LOF750-20B48 to drive my rear surround pair and 4 atmos height speakers

These modules are the Rev B Jan 2024 with the extra 12 volt header, Nichicon caps, 1656 op amps and I must say the build quality is simply outstanding. Hard to believe the power to size ratio of these Class D modules, with sound quality measurements surpassing my 80 pound McIntosh MC7300 beast.

Because my AVR (like every AVR costing under $5K) has only RCA outputs, I must perform surgical mods on each module - solder on an SMD OpAmp, remove 2 resistors, and bridge one jumper. That will be so much fun ... times 9. Yet this still seems like a better solution (SQ and power wise) than RCA-to-XLR adapter cables, but feel free anyone who can talk me out of it.

Also in this pic is an older 4-channel 3E amp module from a different project and I've been extremely happy with! Will keep you posted on my progress, as more parts arrive and I get going on the build.
View attachment 364352
Cool project, please keep us posted.

I recommend you to read this:


I believe the 3e modules have all necessary pins exposed, what is excellent.
 
OP
A

activewire

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Cool project, please keep us posted.

I recommend you to read this:


I believe the 3e modules have all necessary pins exposed, what is excellent.
Indeed the pins ARE exposed for master/slave configuration. Yet I’ve read (in multiple places) that this is generally NOT necessary (perhaps even ill advised?) unless you fall into an exotic use-case of having AM radio receiver parts within the same chassis? My use-case is home theater with blu-ray and AppleTV source, occasional 2 channel audio with Sonos source (also my amp chassis will NOT contain any other components beyond 3 amp modules and power supply).

I will do some testing both ways, although not sure I have the knowledge or equipment to properly evaluate this condition.

Here is one example Post on topic
https://audiosciencereview.com/foru...o-v3-mono-amplifier-review.53474/post-1945437
 
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A

activewire

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This cap seems like is put at the opposite:

View attachment 364410

And by that I would check all components.
Oh wow great catch! You just saved me from an 8 channel / 5.2.3 atmos theater. While Ken Griffey Jr may have mainstreamed a backwards cap, that’s no bueno for circuit boards.

I will check everything when I get back to my home country. Paging @3eaudio please advise.
 
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A

activewire

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My progress is slow. Here I have de-soldered
desolder.jpg

And then re-oriented the capacitor thanks again @Sokel
reorient.jpg

My power supplies have arrived and the dimension is quite small, nearly the same as amp boards. I am playing around with different layouts and now considering perhaps a single chassis for this whole 9 channel build. The white base in this picture is 17" x 14" which is about same size as a typical audio component so what do you guys think should I go one or two chassis?
full.jpg
 

DVDdoug

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Because my AVR (like every AVR costing under $5K) has only RCA outputs, I must perform surgical mods on each module - solder on an SMD OpAmp, remove 2 resistors, and bridge one jumper. That will be so much fun ... times 9. Yet this still seems like a better solution (SQ and power wise) than RCA-to-XLR adapter cables, but feel free anyone who can talk me out of it.
I'd go with XLR adapters. There are potential benefits to a balanced input even with an unbalanced signal, (It's trickier going the other way.)
 

3eaudio

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Hi @activewire great project on multi-channel amp.
  1. for Master/Slave setting, if you don't have AM device around then it is NOT necessary to do this as involve many wire routing. and also think about old device or other amp(hypex?ICE) how can they set Master/Slave in multi-amp case, my experience is that the simple the better for diy.
  2. for RCA input, the best implementation is having a modify in the amp to adopt a single-end to balance convertor, but this is assume you have the capability to do that and want to get best performance with RCA input. Without a modification still can feed single-end input but won't hit the maximum output power as one of the amp output bridge not scale fully balance.So if you don't need full power of the amp and your RCA Gain is good then you don't need to modify the amp.
 

PlasticDoc

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It is a significant issue to sell amplifier boards with electrolytic capacitors mounted in reverse polarity. This is poor quality control.

It is even more problematic to keep quiet about it after the client shows the photography here, and not properly acknowledge the issue and send a new board to the client.

This will hurt 3eAudio credibility.
 
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activewire

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It is a significant issue to sell amplifier boards with electrolytic capacitors mounted in reverse polarity. This is poor quality control.

It is even more problematic to keep quiet about it after the client shows the photography here, and not properly acknowledge the issue and send a new board to the client.

This will hurt 3eAudio credibility.I fixed the board myself in 10 minutes effort.
You saw my post about having fixed the board, not a big deal.
 
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activewire

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IMG_6180.jpeg
I am now about halfway done with the board alterations for single ended RCA inputs. Here are some pics of my workstation and a magnified view of one of the channels with OpAmp added. Hey @3eaudio Is there a decisive way for me to test these alterations?

As expected this is quite a pain and I would gladly have paid an extra $20 per board to not be doing this. @3eaudio please consider the next board Rev just include the OpAmp and have a jumper to select balanced vs SE, very few people are brave like me to solder SMD components.
amp.jpg
 
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