cd preamp for jlh69

farmerjack61 · 17th September 2011, 05:34 AM

Hello there, I have just finished building Selim's version of the JLH69. It is very simple just like me and really doofs. I hooked it up to a subbie last night and the speaker started bouncing around the floor so I would like to harness that 20W of raw doozie.

I went to a JLH site which has all the JLH preamp designs and there is a couple of jfet headphone amps that I like the look of. Can I use one of these or will it be a mismatch. My power amp (the 69) has a 100k across the input - if this helps you.

I really only want to use a dvd/cd player on this one so I don't need low level amplification (i.e. no vinyl or microphones). Just a cd player.

I could just use a 5532 I guess, but would like to use transistors. A sort of low tech - high quality design.

Can anyone show me a 'sure-fire' circuit that will do the job nicely?

In eager anticipation. Phil

srh · 17th September 2011, 05:49 AM

Nelson Pass B-1
Cheers,
Steve.

EUVL · 17th September 2011, 05:56 AM

The JLH69 has enough gain together with CD that you can just use a pot, switched attenuator, or LDR volume between the CD and the JLH.
You can even put the attenuator inside the JLH if you do not have to switch sources.
Anything else adds more distortion.

Patrick

17th September 2011, 05:34 AM	#1
farmerjack61 diyAudio Member Join Date: Nov 2010 Location: Devonport, Tasmania	cd preamp for jlh69 Hello there, I have just finished building Selim's version of the JLH69. It is very simple just like me and really doofs. I hooked it up to a subbie last night and the speaker started bouncing around the floor so I would like to harness that 20W of raw doozie. I went to a JLH site which has all the JLH preamp designs and there is a couple of jfet headphone amps that I like the look of. Can I use one of these or will it be a mismatch. My power amp (the 69) has a 100k across the input - if this helps you. I really only want to use a dvd/cd player on this one so I don't need low level amplification (i.e. no vinyl or microphones). Just a cd player. I could just use a 5532 I guess, but would like to use transistors. A sort of low tech - high quality design. Can anyone show me a 'sure-fire' circuit that will do the job nicely? In eager anticipation. Phil

17th September 2011, 05:49 AM	#2
srh diyAudio Member Join Date: Mar 2004 Location: Whangarei. NZ	Nelson Pass B-1 Cheers, Steve. __________________ The older I get, the more simplicity appeals.

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17th September 2011, 05:56 AM	#3
EUVL diyAudio Member Join Date: Oct 2003	The JLH69 has enough gain together with CD that you can just use a pot, switched attenuator, or LDR volume between the CD and the JLH. You can even put the attenuator inside the JLH if you do not have to switch sources. Anything else adds more distortion. Patrick

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