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PeeCeeBee V4H GB

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#1,462
Q1 / Q2 Matching

I'm having a hard time matching Q1 - Q2

Most BC546B I found have hfe around 415
and most BC556B hfe around 290 -> 330

I have 2 best couples BC546=276 / BC556=281 wich is good
and BC546=402 / BC556=341 .... not so good

And I need some more for another amplifier.

My sources for bjt are Mouser and Farnell.

Any idea for a source of BC546B with a hfe lower than 400 ?

Thanks a lot

JM
 
#1,464
J.M.K said:
I'm having a hard time matching Q1 - Q2

Most BC546B I found have hfe around 415
and most BC556B hfe around 290 -> 330

I have 2 best couples BC546=276 / BC556=281 wich is good
and BC546=402 / BC556=341 .... not so good

And I need some more for another amplifier.

My sources for bjt are Mouser and Farnell.

Any idea for a source of BC546B with a hfe lower than 400 ?

Thanks a lot

JM
Click to expand...

BJT & Bipolar Transistors | RS Components

BJT & Bipolar Transistors | RS Components

I get the Onsemi "BTA" suffix ones from the RS India site. Also am going to get an bunch of them from Taiwansemi next month. The NPNs have an average hFE of 275 and the PNPs 345 (all the PNPs seem to have a higher gain). Hope this helps your case.
 
#1,467
One of my LEDs goes out when I plug in my speaker. I'm trying to test one channel only. Using SMPS, no other modules at all.



Things I've tried:
Completed VAS biasing
Completed offset trimming
Completed mosfet biasing
Heatsink is connected to chassis ground
No continuity between output terminal and heatsink
jumpers connected

One chassis ground point, speaker return, sgnd, pgnd
 
#1,469
Yes I have -ve hooked to the smps -v. I am a bit new at this am I missing something obvious here? SMPS screws are replaced with longer ones and tapped in to the chassis / chassis ground
 

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#1,470
Really need better pictures (multiple angles at high resolution) and tell us exactly what SMPS you are using.
Have you verified you have correct voltages from +/-Vdc with and without the amp board?

Edit: Could be wrong, but looks like a single voltage SMPS by your pic? You need dual voltage smps.
 
#1,475
Hi,
Yes I have used SMPS with double output for positive and negative voltage out, with earth as the center. For my V4H I use two 800VA with ±55V (500VA continuous load at 25° C).
And there are many with double voltage output (±) in the market, many suppliers set up to the voltage you want within given parameters, so there is probably always something to find that fits.
Ref to my previous post #1457 with a picture of the amplifier.
Regards
Helge
 
#1,478
GB UPDATE:

Torvbakkane - 6 PCBs - SHIPPED
Faizal Mansar Alam - 2 MODULES - SHIPPED
J.M.K - 4 PCBs - SHIPPED
prairieboy - 2 PCBs - SHIPPED
nrabbit - 2 PCBs + MOSFETS - SHIPPED
deps - 2 PCBs - SHIPPED
Greg1017 - 2 PCBs + MOSFETS - SHIPPED
CitizenKane - 4 PCBs - SHIPPED
surajspai - 2 PCBs - SHIPPED
Rick G - 4 PCBs - SHIPPED
blek stena - 2 PCBs - SHIPPED
routhun - 2 PCBs - SHIPPED
apnneto - 2 PCBs - SHIPPED
RobSoet - 4 PCBs + MOSFETS - SHIPPED
Pistollero - 2 PCBs + MOSFETS - DELAYED DUE TO TEMPORARY SUSPENSION OF SERVICE.

The suspended one will be shipped as soon as shipping service resumes to Portugal. I exhausted my last set of the SMD diodes and the subsequent batch from RS took about three weeks to come due to some complication. As a result the last few shippings got delayed.

Thanks to everyone for your patience.
 
#1,479
still trying to matchv Q1 / Q2

J.M.K said:
I'm having a hard time matching Q1 - Q2

Most BC546B I found have hfe around 415
and most BC556B hfe around 290 -> 330

I have 2 best couples BC546=276 / BC556=281 wich is good
and BC546=402 / BC556=341 .... not so good

And I need some more for another amplifier.

My sources for bjt are Mouser and Farnell.

Any idea for a source of BC546B with a hfe lower than 400 ?

Thanks a lot

JM
Click to expand...

I'm still into it.
The best Hfe match I got are some BC556B around 348 and
almost all BC546B around 414.
Is it going to actually make any audible issue ?
Anybody knowing a reliable source for something better ?

JM
 
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