David builds dual mono 3e Audio 480-1-29A Amplifiers

[DaveFred]

Hello,

Up til now I have been using vintage Adcom amplifiers (GFA-555II's), but they all seemed to have some background noise/hiss and have been looking for something quieter. Not long ago I purchased a previously enjoyed Parasound P6 preamp for how it handled sub out and had XLR outputs with the though of buying a Parasound A21+, but they are big $$$, even used. Ran across Amir's review of this amp and thought it would be a "cheap" way to get a "blue" rated amp.

I am not an electronics expert, just a middle aged guy who liked to play with Lego as a kid. This will be a work in progress, so, while I hope I don't make any mistakes, If I post any, feel free to critique and offer suggestions.

Things purchased so far,

2 x 480-1-29A board from 3e Audios Aliexpress web page, $299.23 delivered to Canada

https://www.aliexpress.com/item/1005004784269635.html

2 x BRZHIFI BZ2109 amplifier chassis purchased from Tokban Audio on Aliexpress (best price I could find, and all black), $180.84 delivered to Canada

https://www.aliexpress.com/item/1005006820926972.html

2 x Mean Well pn#UHP-500R-48, 502 watt 48 volt power supply, no fan, relies on large case plate for cooling, $287.86 Canadian from Digikey

2 x Amphenol Audio XLR connectors pn#AC3FDZB-AU, $20.50 CDN

2 pair x Aliexpress ST650G fancy speaker binding posts, $20.56 delivered to Canada

https://www.aliexpress.com/item/1005006159046962.html

2 x Lanboo 110v x 15 amp latching LED lit switches with cabled housings, $30.66 delivered to Canada

That is a total of $839.65 Canadian ($604.56 USD, $558.95 Euro) spent so far, freight is a big part of some of these numbers, so it could be higher or lower depending on where you are.

Here is what I am starting with,

Nothing seems to have been damaged in shipping and I have some work ahead of me...

David.

 

[DaveFred]

Once everything was opened everything up I put painters tape on the aluminium panels so I didn't scratch them up as I worked on the amp, and I laid out the parts how I had imagined them to fit,

One thing I knew before I ordered the parts was that the 3e 480-1-29A amp board/integral heatsink was going to be wider than the amp case was taller internally,

Amp board/heatsink is 3.3435" wide,

and chassis is only 3.308" tall internally

But that is only a difference of thirty five and a half thou or a little over 1/32 of an inch.
@Roland68 Suggested to use washers between the top/bottom covers of the case and the heat sinks to allow for the extra room, but I decided to go with my initial plan of grooving the top and bottom covers about 1/32 on each side, which would only be removing about 1/3 of their thickness.

Had to bash together a little jig, and then used a router with a 1/2" spiral bit to mill the groove in the aluminum.

Worked quite well,

Next up, A bunch of drilling...

 

[3eaudio]

it just looks awesome @DaveFred
one power supply is good enough for 2 amp board if you not keep running very high power, it may can save some space for internal wiring.

 

[DaveFred]

Laying out mounting holes for the 3e 480-1-29A amp board on the heat sink, luck would have it, all three "rows" of screws landed between heat sink vanes.

Wasn't so lucky with the Power supply. Had to drill right next to a vane and got mostly seated in the slot for the power supply.

So far so good,

Next up, layout and drilling for switch, XLR input and speaker binding posts....

(are the blow by blow pics too many?)

 

[DaveFred]

Time for front and rear holes, Front switch is going to be dead center in the front panel and the size rounds up to 7/8". Going to pilot with 3/32" and use a step bit to enlarge the hole so I actually get a round hole.

I did lay out the rear connectors several times trying to see how to make them best work with the layout inside the case, and this is the best I could come up with.

Rear XLR hole is also 7/8"

Hole needed slight filing for XLR connector to fit as it was not fully round (file is a gentle convex on other side),

Binding posts,

Round up to 15/32",

Decided to tap the holes for the XLR connector, M3 flat head machine screws will be used, just like what came with the case for the Power Entry connector. Could have through drilled and used nuts on the other side, but this seems more elegant.

And here we are today,

Next up, need some bottom holes for feet and some cable management clips, take it all apart to remove some anodizing from each part so the ground is "continuous" around the amplifier...

 

[FrantzM]

That's next level DIY...
Wow!

Peace.

 

[TheWalkman]

Looking good so far!

 

[3eaudio]

@DaveFred can make the input signal wire shorter and twists them will be better.

 

[CapMan]

Round up to 15/32"

Fantastic work - I can't imagine doing this myself. I am so grateful we use the metric system when I see fractions like 15/32 in measurements !

 

[DaveFred]

I am so grateful we use the metric system when I see fractions like 15/32 in measurements !

If I was thrown into imperial fractions a mature adult, I am sure it would be a challenge, but I have been dealing with them for 40 years+, so the math in my head is second nature.

 

[DaveFred]

Time to layout for the feet and some cable clamps,

Using a single flute countersink to deburr the through holes,

(hard to see, deburred on left, raised burrs on right)

Feet on,

Using a 120g flap wheel on a cordless drill to remove the paint around where screws will "clamp" the case together to allow for the "ground" to be around the entire case.

Next up, start to put it back together and get to the wiring...

 

[DaveFred]

Painted the bottom of the 480-1-29A amplifier board heat sink with thermal paste before fastening to the chassis heat heat sink,

Just a small amount squeezed out,

Did the same thing with the power supply,

Fastening the power supply to the other side chassis heat sink reminded me of the children's board game "Operation"...

Started the wiring with the DC from the power supply to the 480-1-29A amplifier board,

I didn't fully understand how the lamp in the switch was wired, if I needed to run both the hot and neutral through it in order to make the lamp work, so I tested it with a Variac. That way I could ramp up the power and blow it up slowly if I was doing it wrong.

Turns out it needs to be wired like a double pole switch with neutral and the hot switched as well in order for the lamp to work.

Time to start on 110v into the power supply. First up, ground, with a machine screw in from the outside of the case, star washer, ground from power entry connector, ground from power supply, washer and nylock nut,

Then 110v from the power entry to the switch and back to the power supply,

Not much more to go, signal in, signal out...

 

[JeremyFife]

Looks great, and completely confirms my thoughts that DIY amplifiers are not just 'screwing boards into a box' - there's some craftmanship on display here.

Great thread, thanks

 

[3eaudio]

SOTA diy......

 

[DaveFred]

Installing the amplifier outputs, the binding posts have plastic insulators that keep the posts centered and isolated from the chassis so they don't ground out, you can see the "step" on the round plastic bits in the pic,

Rather than just stick a bare wire into the screw clamp of the binding post, I am using a wire ferrule that gets crimped,

Outputs wired,

Just input wires left to do!

 

[DaveFred]

Redid the speaker out wiring connection, wired the XLR input, did a basic test of amp and buttoned the pair up today,

I don't think I stripped the wires far enough previously which caused the wire ferrules to crimp too small, this time I made sure the stripped wired extended out the end of the ferrules about 1/16". Also don't think the screw clamps on the output binding posts were grabbing onto enough of the ferrules, so I ground a bit of them away so the ferrules "pushed in" more under the screw clamps.

Here is a drawing I "took" from this forum (not sure who posted it first) and modified to my liking to show the wiring for the XLR connectors.

There was quite a discussion in a couple build threads on various ways to wire up the XLR, but I settled on how the sample from 3e Audio what shipped to Amir and how @daniboun wired his (<-Shout out for confirming the drawing!)

to make soldering the XLR input connectors easier, I first tinned both the wires and connectors,

Also used a bit of heat shrink tube as a strain relief,

Just a matter of snapping in the JST connector and screwing the XLR connector to the back of the chassis,

Here is a shot of the two chassis side by each, a combined width of a "normal" piece of stereo equipment, ~17" (~430mm)

Went to fire up and amps to test the power supplies and had a brief moment of panic before I realized I had not installed the fuses yet. Meanwell UHP-500R-48 draws 4.8 amp, 4.8*1.25=6, so I installed 6 amp fuses.

Both power supplies measured remarkably close,

Testing the amp, output from my laptop to SMSL balanced output DAC to mono 3e Audio 480-1-29A Amplifier.

Revel in the output from the ultra revealing high end full range open baffle speaker I used for testing,

Testing mono 3e Audio 480-1-29A Amplifier for the first time

Both amps worked, no trouble shooting required.

Couple shots of both amps all buttoned up,

Need to bring them into the house and wire them up to my main system to see how they compare to the Adcom GFA555 II they are supposed to replace. My hope is that they are MUCH quieter.

 

[somebodyelse]

For the XLR connection the recommendation is to connect pin 1 (shield) to chassis as close as possible to the connector. Some connectors have this built in, with a spike at one mounting screw to pierce paint etc. ensuring a good connection to chassis. Others don't, so you have to make your own arrangements. This assumes a real differential input.
https://www.ranecommercial.com/legacy/note110.html
http://www.hinton-instruments.co.uk/archive/reference/aes48.pdf
https://www.jensen-transformers.com/application-notes/ - AN007 has thorough coverage of grounding issues, and how to test for a 'pin 1 problem'

 

[daniboun]

Redid the speaker out wiring connection, wired the XLR input, did a basic test of amp and buttoned the pair up today,

I don't think I stripped the wires far enough previously which caused the wire ferrules to crimp too small, this time I made sure the stripped wired extended out the end of the ferrules about 1/16". Also don't think the screw clamps on the output binding posts were grabbing onto enough of the ferrules, so I ground a bit of them away so the ferrules "pushed in" more under the screw clamps.

View attachment 405072

Here is a drawing I "took" from this forum (not sure who posted it first) and modified to my liking to show the wiring for the XLR connectors.

View attachment 405097

There was quite a discussion in a couple build threads on various ways to wire up the XLR, but I settled on how the sample from 3e Audio what shipped to Amir and how @daniboun wired his (<-Shout out for confirming the drawing!)

to make soldering the XLR input connectors easier, I first tinned both the wires and connectors,

View attachment 405073

View attachment 405074

View attachment 405075

Also used a bit of heat shrink tube as a strain relief,

View attachment 405078

Just a matter of snapping in the JST connector and screwing the XLR connector to the back of the chassis,

Here is a shot of the two chassis side by each, a combined width of a "normal" piece of stereo equipment, ~17" (~430mm)

View attachment 405079

Went to fire up and amps to test the power supplies and had a brief moment of panic before I realized I had not installed the fuses yet. Meanwell UHP-500R-48 draws 4.8 amp, 4.8*1.25=6, so I installed 6 amp fuses.

View attachment 405085

Both power supplies measured remarkably close,

View attachment 405086

View attachment 405088

Testing the amp, output from my laptop to SMSL balanced output DAC to mono 3e Audio 480-1-29A Amplifier.

View attachment 405090

Revel in the output from the ultra revealing high end full range open baffle speaker I used for testing,

Testing mono 3e Audio 480-1-29A Amplifier for the first time

Both amps worked, no trouble shooting required.

Couple shots of both amps all buttoned up,

View attachment 405099


View attachment 405098

Need to bring them into the house and wire them up to my main system to see how they compare to the Adcom GFA555 II they are supposed to replace. My hope is that they are MUCH quieter.

Well done and nice job
Did the same amp many months ago but with dual Mono 3E Audio boards in one case )

"Bamboo Project" : Dual Mono 3E Audio 480-1-29A Amplifier

Hi amigos, Following the ASR review of the 3E Audio 480-1-29A Module, I decided to roll up my sleeves and show you that with a little elbow grease, you can create a very beautiful amplifier based on these nice 3E Audio modules. I called this project, "Bamboo"> the pictures will speak for...

audiosciencereview.com

 

[DaveFred]

Just thought I would post a couple of pics of misc items I used in the build and what hand tools I used for those contemplating building one of these amps, or any amp really,

A drill press is really handy!

You don't need a floor model one, even an inexpensive bench top one will make the drilling all the holes easier, you will at least need a hand drill.

Here is the assortment of hand tools I ended up using,

For wire, I used 14awg silicone jacketed wire,

These mixed boxes can be picked up from several online retailers.

I needed four different type of crimp connectors and I elected to use brand Molex rather than Happy Lucky China Co. versions

to connect to the power supply and for ground I used Ring ones pn# 0190730072

blades on the amp were 0.246" so I used 0.250" wide pn# 0190030040
blades on power inlet were 0.192" so I used 0.205" wide pn# 0190030062
blades on power switch were 0.184" so I used 0.187" wide pn# 0190030056

 

[restorer-john]

Great job!

Did you tap the heatsinks (between the fins) for the amp/psu mounting screws or screw/nut them?