DIY Discrete Dynamics Class A/B amp and Class A preamp/headphone amp

[sachu888]

Hello all,
My friend has recently designed a Class A/B amp using Toshiba BJTs. He has successfully tested a prototype and results are very encouraging. It will be an easy build, even for first timers. The Amp PCB(stereo) will have onboard power supply, protection circuit.The heatsink requirement is not huge and can be installed inside the cabinet.

below are the specs of stereo amp:

Power output : 70~120W into 8 ohms, 110~180W into 4 ohms.(continuous avg per channel.)
THD : <0.03 % at rated power 20-20000Hz, 0.003 % @ 1kHz half power
Signal to noise ratio : 112dB
Frequency response : 3Hz-250kHz.(-3dB)
Input impedance : 25k ohms
Input sensitivity : 1V rms for rated power
Damping factor : 200, @ 8 ohms, 20-500Hz
Power supply : 30-0-30, 40-0-40V AC 300-500VA, 9-0-9V AC for protect

PCB

Regards
Sachin

 

[sachu888]

I can offer fully soldered modules mounted on heatsink, if anyone has interest. one will only have to make IN/OUT , and transformer connections. The PCb will have connectors for all the wiring, so no soldering will be required on PCB. This will be a really nice AMP.

Regards
Sachin

 

[Opa1]

I like the way the in and out are on the same side of the board. This would be a easy build with the complete board. Show and tell some more.

 

[sachu888]

Updated layout

There are two types of modules

1. 70W PC

Bjts: Toshiba 2SC5200N/A1943N
Power caps , 4 X 6800uf, 50W

2. 120W pc

Bjts: Toshiba 2SC5949/A2121
Power caps , 4 X 10000uf 63W
PCB size is 280mm x 120mm. There are two heatsinks mounted directly on PCBs. Here is a pic of heatsink

He has also designed a preamp using all discrete components.

Preamp PCB is 100mm x 100mm

Regards
Sachin

 

[sachu888]

PCBs also arrived , couple of days ago. We have also received all required components, only big power capacitors are pending.

Regards
Sachin

 

[StevenZ]

Those look good.

 

[Thermionics]

Interesting...does it use the same heatsink for both wattage versions?

 

[sachu888]

Yes, heatsinks are same for both the versions. There are total two heatsinks for one amp. They are sufficiently enough.

Regards
Sachin

 

[sachu888]

Update:
My friend has tested the power amp yesterday. Its playing continuously since then. The amp is very stable and sounds superb he said. He will test the preamp today. I am attaching few pics

Excuse me for low quality mobile pics.

Regards
Sachin

 

[Thermionics]

The one thing that (somewhat) scares me off is the SMD components - I hate trying to solder those!

What is the planned price-point for the 70W version?

Thanks!

 

[sachu888]

The one thing that (somewhat) scares me off is the SMD components - I hate trying to solder those!

What is the planned price-point for the 70W version?

Thanks!

We are offering fully soldered modules. Had he used through hole components, the PCb size would have been even bigger.
The price is $100 for 70W including shpping, and Class A preamp cost $45, shipping $20. Both the boards are pre soldered.

Regards
Sachin

 

[sachu888]

The preamp has also been tested.It has been housed in a temporary set up with Amp for testing. The combo is running non stop since two days. The amp is very stable.

Regards
Sachin

 

[sachu888]

We are offering fully soldered modules. Had he used through hole components, the PCb size would have been even bigger.
The price is $100 for 70W including shpping, and Class A preamp cost $45, shipping $20. Both the boards are pre soldered.

Regards
Sachin

Let me know if anyone wants to have these. I can start shipping in 10 days.

Regards
Sachin

 

[sachu888]

First review https://www.lencoheaven.net/forum/index.php?topic=30648.0

Regards
Sachin

 

[sachu888]

Ver 2,
Amp PCB is now Black ,2MM thick and has provision for input film caps. Only 120W is available, 75W will only be available on request.

Preamp module comes with onboard miniature Alps pot.

Regards
Sachin

 

[mhardy6647]

dang.
threads like this give me the itch to build something (anything).

Not like I need anything or anything...

Nice lookin' project(s).

 

[sachu888]

It's one of the easiest project and also very nice.

Regards
Sachin

 

[UncleBingo]

Nice work! Is the preamp output level and impedance suitable for stand-alone use with standard power amps? (I don't need numbers just a yes or not so much will suffice)|
Also, what are the power-supply requirements for the preamp?

 

[rogerfederer]

replied to your AK BT thread

 

[sachu888]

Nice work! Is the preamp output level and impedance suitable for stand-alone use with standard power amps? (I don't need numbers just a yes or not so much will suffice)|
Also, what are the power-supply requirements for the preamp?

Yes, it is suitable with any power amp. The power supply is onboard. you will need a 15-0-15 or 18-0-18, 0.5A transformer.

Regards
Sachin