ESp P3 amp on Cheap 150w amp board

[Vintage Amp Builder]

Is the pcb for the 150 w amp suitable for esp P3 amp??? Ill be cutting the collector tracks and will put 220 ohm resistors in series with the collectors of Q1 and Q2 and bypass D1 R10 and R12. I have attached the P3 diagram and the 15o w amp pcbs and ckt diagram .

 

[Ian Finch]

P3 is a discrete CFP design and the PCB/schematic shown is an integrated Darlington (TIP142/7) design. 'Pretty hard to marry those without a mess, neglecting the front end differences even.

 

[Bone]

Not compatible I'm afraid. As a matter of interest where did you get the boards for the 150w amp?

 

[Vintage Amp Builder]

I was goin to build the amp up till the driver stage (BD 139 140) and connect the power transistors ( I'm using 2n3055 and mj2955 BTW) with flying leads.

 

[Vintage Amp Builder]

Hey Bone here's the link 150 Watt Power Amplifier Circuit Board

 

[Bone]

Thanks.

 

[Vintage Amp Builder]

Hey bone can I use the board now??????

 

[AndrewT]

You don't need to cut the collector tracks.
Bend the transistor collector lead up through 180degrees. Solder on a collector resistor pointing down. The new three legged device will fit the old pad arrangement.

Add pads for base stoppers on all your driver and output devices. Again a bent base lead with added resistor allows for no PCB modification.

Add a resistor to convert the input C (change the C from 100pF to somewhere from 330pF to 1nF) to an RF R+C filter.

Add HF decoupling to the collector leads of the output devices.
Add MF decoupling to the supply rails near the output devices.
Add MF decoupling near the input stage supplies.

 

[Vintage Amp Builder]

Thanks a lot. Here are the pics of my P88 preamp im goin to use with the amp. Im using the version ROd used for his Gainclone amp project. i hav not yet mounted the output caps. i was wondering whether i should use input caps to protect my source incase the opamp fails.

 

[AndrewT]

Make the highest gain resistor fixed, not switched.
Then switch in alternative gains.

 

[Vintage Amp Builder]

Should I use input caps????? Can the volume pot be before the opamp???

 

[AndrewT]

Why add input cap? For DC blocking, if a source does not have it?
Why add an extra attenuator? To prevent input stage overload, if a source has sufficient voltage to overload the opamp?

 

[Vintage Amp Builder]

Here r some pics of my transformer. I got it for free from my dads friend

 

[Vintage Amp Builder]

I just finished building the amp . 1 ch worked fine but the driver stage of the second one blew up . Fortunately the output trs are safe . The mJ2955 of that ch got hot but it's workin fine. I also damaged my multimeter