My Babelfish J Monoblock Project

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Wakoo CtC

piano finish .......

:)

Thanks!

Do you think red is too much?

B737ECEB-300A-421C-A912-002ADF7A1FF1.jpeg

Power supply finished

F19C9CB0-583A-4D51-AB14-0E489021E4DA.jpeg

Rear panel finished

7C2E3C15-99B6-446D-9C12-3C07D1A8D9E3.jpeg

No one asked about the 8” hole in the side of the case, I guess everyone guessed it was for the transformer? Ever since I bought these beautiful Toroidy transformers I hated they would be hidden in the case and never seen again. This build I figuout a way. The transformer is completely supported by the aluminum brace, there is a 1/4” gap beween the perimeter of transformer and the case to allow air into the case for cooling. The aluminum brace also serves as a heatsink for the rectifiers. Am I crazy?

6578307B-7607-417B-9421-F732B13CFD26.jpeg

Was hoping to have one amp done before we flew out for the holidays, but need some more parts. Going to have to wait till next year now.
 
Need to start packing for the holiday trip to the mainland. But thought I would show where I ended up today.

The power supply along with the power on relay is tested and operational. The case is now pretty much together. Changing the 12v system that operated the fan and the relays on the slow charge circuit. Need about a day to finish up boards and wiring.

FYI, the heatsinks and 3/8” aluminum panel they are bolted too weigh in at 43.2 lbs.

But here are some pics to give final look and scale of size.

FA9FD60D-FCA9-428C-8ECF-B6C0C72F81F3.jpeg

65313E51-B37E-4D5A-84BE-98BB55F4DE41.jpeg

F30B8920-52F7-4CEE-91F7-EEC3197C360E.jpeg

B51666DC-B8FB-4412-BD49-2BA8498F90D3.jpeg

6E5A913A-4434-4FB6-9D45-8758B3B095B8.jpeg
 
Official Court Jester
Joined 2003
Paid Member
You referring to something like a pair of these?

View attachment 723699

Would they just bypass the large caps? Or bypass the whole power supply?

Thanks ZM

yup , motor-run caps

bypass "just" each final cap in supply , so one per rail

on this side of Big Splash , I'm using either Icar or Ducati caps , in plastic case, they're of awesome quality
 
Been on the mainland for the holidays. 3 cities visited, over 10k miles flown, trip was fun, but glad to be back home!

Soundhappy, dBel84, Juntuin thanks much for the compliments! Sorry for delay in response.

Zen Mod, ordered the caps. Should be in this week, thanks.

Spent yesterday and today so far on the amp. In the attached pic you can see how I matched up the Mosfets. The two numbers by each chip are the readings from testing at 13v (2 decimal points) and 30v (3 decimal points). I gave more weight to the 30v testing since I’m running higher voltages

I bought matched resistors also, uppers are all 1.003 Ohm, lowers all 1.004 Ohm.

I should have just bought new daughterboards, took a lot of time removing all the resistors, wires and Mosfets.

In the last build I ran separate wires from the FE board to each daughterboard, this time I’m running a jumper between daughterboards. Seems like this way would be better?

That’s a lot of heatsink for 12 Mosfets! I placed the Mosfets 1/3 of the height of the heatsink up from the bottom. The upper and lower heatsinks do not touch, except for the mounting angle on each end. There is a separation of 3/16 between the 3/8” aluminum plates and 1 1/4” between the actual heatsinks. The 3/16” gap goes to the interior of the chassis to allow air in and out through the fan.

B075A78A-E5F4-4206-8E42-B44D20B5F308.jpg
 
I see nothing to complain about , so I'm silent

:clown:

Thanks, good to hear!

Mostly finished up yesterday and powered it up this morning. Yet to connect input and output to connectors.

Everything is basically the same as before, except for new matched source resistors and Mosfets. I did change R24 to 75k, now able to get 540mV across source resistors.

20v across R11, within a mV or two at output.

Only cooking for about 45mins, still only a little more than warm.

282BABF0-F7E6-4CC3-ACD9-79D4A529DDD9.jpg

57062FB8-FD45-4E15-98E9-55FB9AF080E7.jpg

828C66B8-A133-4177-9066-AFA575D68A50.jpg

Going to the beach for the rest of the day, so fine tuning and follow up adjusting later.
 
I do have a question, I’m using a MS35 inrush current limiter on each leg of the transformer outputs as a slow charge. After a few minutes of running the positive side MS35 is 68 degrees Celsius, the negative side MS35 is only 23.2 using my laser thermometer. As a baseline the chassis measure 22.6 Celsius.

Is this normal? Or a defective MS35?

In normal operation I have an Amperite 12D1-100SST1 adjustable timer that with 12v relays bypasses the MS35’s after about 40 seconds.
 
Zen Mod and dBel84, thanks for commenting.

For initial start up, I started with basics. Step by step to minimize a whole lot of problems at once. At this point in the startup I have the 12v bypass relays idle. Before connecting the main transformer into the circuit I had tested the 12v relay system, so I know it works. I was also curious as to the heat that the MS35’s put out so I would know how far away to keep close wiring. I was surprised one was so hot and the other almost ambient temperature.

FYI, the relays only make a connection between the legs of the MS35’s, they stay in the circuit. The idea is that electricity should take path of least resistance and connect through the relay and not the resistance of the MS35’s.

I wonder if I should increase the time to bypass? How long would you think it takes the MS35’s to pass full voltage? I would assume I would want to bypass after that to keep from having a spike in voltage?
 
Hihi,
Nice an ZM on the Pad like a „Bibel“. Need more from your build.

Here is an overview of my build. Let me know if I missed anything.


Power supply;

Soft start boards from the DIY store

MS35’s, as mentioned earlier, for the slow charge circuit

1500 VA, 38v secondary, transformers from Tororidy out of Poland

4 ea 82,000uF Rifa capacitors

PS boards from DIY store, w/8 ea 15,000 Mundorf capacitors

Roughly 50dcv rail voltage


Control circuits;

My preamp has a output trigger that I utilize for on/off

I have a Crydon MCX24OD5 solid state relay that receives the 5v signal from the pre to switch the power on to the soft start board

Since I have a 12v fan and need to drop out the MS35’s I utilize a small 12v, 2 amp transformer for supply, switched using an Amperite 12D1-100SST1 solid state timer and Omron G8P-1A2T-F relays.


Heat sinks/case;

Each monoblock has 6ea of the Ebay, Chinese Nelson Pass look alike heatsinks.

Three heatsinks are bolted to a 10” x 16” x 3/8” aluminum plate in an upper and lower configuration

Cabinet is painted/laminated 3/4” Medex, aluminum supports, 22” t x 19 1/2” d x 6” w (9 1/4” counting faceplate and heatsinks).


Amp design;

Zen Mods schematic is below, with notes for my build. If not for Zen Mods help I would not have been able to build this, thanks!

I used all PRP resistors, except for the 3 watt Mills.


And BTW, sounded fantastic before this rebuild! Hoping for only better!


A9017498-F447-40DB-9C93-DE40BF35FE41.jpeg
 
Spent some more time on the amp today.

Connected to the 12v system. Before the timer bypasses the MS35’s their temps rise to 60 degrees Celsius (both), the timer kicks in about 30 seconds after, then about 30 minutes later the MS35’s temps drop to about 2 degrees Celsius above ambient.

Made the final connections to the inputs and binding posts.

My next speaker project has 500wpc Hypex’s powering the 18” woofers, so for convenience I have both male and female XLR’s so both feeds to the speaker comes from the amps.

Not the best setup for testing, with the heatsinks upside down and laying flat, but temps seem to stabilize at 50 degrees Celsius. I did have a small fan running about 6 feet away to keep some air movement in the room.

DF7D8D34-DF31-4963-A216-06C874F5E50D.jpeg

Not sure if the power to the house changes between morning and afternoon, going to check, but the amps voltages were lower than where I set them this morning. For my testing this afternoon I had 115.3v coming out of the wall.

I have TP3 one turn back from max, here is how each mosfet measures after 45 mins of running, 50 degrees Celsius measured about 2” from the closest mosfet on the 3/8” backer plate.

First number is what the mosfet tested at 13v, second at 30v, across source resistor.

I can’t understand the big variation. Even the resistors are matched. Doesn’t seem to be any rhyme or reason for the variation.

Should I move them around for better matching upper and lower? Advice?

Positive Bank

4.15, 3.988, .532
4.15, 3.988, .545
4.14, 3.988, .551

4.14, 3.990, .544
4.14, 3.990, .542
4.17, 3.991, .528

Negative Bank

4.15, 3.984, .536
4.15, 3.984, .549
4.17, 3.985, .536

4.14, 3.985, .553
4.15, 3.985, .546
4.15, 3.986, .537
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.