Pass project for 88dB speakers? A75?

FATHER · 1st May 2011, 10:57 PM

Did a lot of reading in the last few days and now i'm even more confused... Hundreds of pages... Lots of data and opinions... But, a few times i saw Nelson's recommendation for hungry speakers : The A75.
Building this design with TO3 transistors would be kinda expensive so i wonder if there is another solution.... A very good friend of mine sugested that i should make the A20 but i could not find anywhere Motorola 2N5877 .
My speakers can be seen HERE .
I don't need a lot of power. Listening levels are always moderate so i guess 40-50 watts would suffice... Please help me decide. If there are ready made PCB's would be very nice. Thank you.

Nelson Pass · 2nd May 2011, 05:09 AM

That would be 2N5878, I think.

There are lots more designs simpler and with more power.
Maybe you want to look at the Burning Amp #1 or #2.

FATHER · 2nd May 2011, 12:21 PM

The midget inside my head is pushing me towards the single-ended version... That would be the Burning Amp #1. Advice much appreciated, Papa...

I use high-end music source consisting in Rockna WaveQuest transport and DAC. The transport is a special memory player, very similar to the PerfectWave from PS Audio. The digital to analog converter uses the discrete ladder module from MSB Technology . These babies need a real amp now...

I think i'll go with a dual-monoblock design. Two smaller units instead of one big animal in my livingroom would contribute to a better WAF... I'm thinking of an external powersource, maybe regulated, because 230V power in my country is really bad. I would like to use VU-meters or some Magic Eye tube audio-level indicator but that depends on the chassis.
The frontplates will be covered with genuine leather ( yeah, i'm nuts

)
It's a long time project, but i'm still young... I'll be back from time to time with updates and, i'm sure, with questions.

Maybe the moderator would be so kind to change the name of the topic in :
Pass project for 88dB speakers? The Burning Amp #1 .

FATHER · 4th May 2011, 08:06 AM

If i got it right : i could replace irfp240 with SJEP120R100 J-Fets ?

Nelson Pass · 4th May 2011, 08:13 PM

You absolutely could.

FATHER · 4th May 2011, 08:36 PM

Brilliant!

Now regarding the frontend : is there a better option ( even more expensive, from another Pass amp ) or simply using a separate stabilized power source would do ?

Cleaner power + R100 J-Fets will make this amp The Son Of Pass?

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1st May 2011, 10:57 PM	#1
FATHER diyAudio Member Join Date: Feb 2007 Location: Moronia	Pass project for 88dB speakers? A75? Did a lot of reading in the last few days and now i'm even more confused... Hundreds of pages... Lots of data and opinions... But, a few times i saw Nelson's recommendation for hungry speakers : The A75. Building this design with TO3 transistors would be kinda expensive so i wonder if there is another solution.... A very good friend of mine sugested that i should make the A20 but i could not find anywhere Motorola 2N5877 . My speakers can be seen HERE . I don't need a lot of power. Listening levels are always moderate so i guess 40-50 watts would suffice... Please help me decide. If there are ready made PCB's would be very nice. Thank you.

2nd May 2011, 05:09 AM	#2
Nelson Pass The one and only Join Date: Mar 2001	That would be 2N5878, I think. There are lots more designs simpler and with more power. Maybe you want to look at the Burning Amp #1 or #2.

4th May 2011, 08:06 AM	#4
FATHER diyAudio Member Join Date: Feb 2007 Location: Moronia	If i got it right : i could replace irfp240 with SJEP120R100 J-Fets ?

4th May 2011, 08:13 PM	#5
Nelson Pass The one and only Join Date: Mar 2001	You absolutely could.

4th May 2011, 08:36 PM	#6
FATHER diyAudio Member Join Date: Feb 2007 Location: Moronia	Brilliant! Now regarding the frontend : is there a better option ( even more expensive, from another Pass amp ) or simply using a separate stabilized power source would do ? Cleaner power + R100 J-Fets will make this amp The Son Of Pass?

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