Marsh headphone amp from Linear Audio

[KMossman]

Thank you Georg but no gif appears at all - just blank .

[stormsonic]

A Paul Kemble web page - John Linsley Hood preamp designs.

[RNMarsh]

Originally Posted by RNMarsh

here is the original JLH headphone amp circuit --- RNMarsh

??

I bought about 2 yrs ago a JLH headphone amp being promoted on this DIYAudio site.... it doesnt measure as well, either. What else can i say. I even paid about $450 for a finished product off a headphone only site and wasnt pleased with the results, either. Now that one also sits unused as more wasted money. :-( It was all IC based.... but couldnt drive low Z headphones well... even with a buffer IC after the opamp. The sound matters. Measurements matter. Seemingly small changes matter.

Thx-RNMarsh

[Telstar]

JLH amp IC based? the sold u a fake.

A real JLH circuit is in my do do list (after yours, yay!)

[Guiness]

Adding this to my ever going collection of headphone amps!

[Pingushome]

Originally Posted by jackinnj

After the turn of the year I will put together batches of parts (including the matched transistors.)

In the interim, I'll put together a BOM with the device sizes.

Hi Would be intrested in pcb and / or parts pls let me know when they become avaliable, even the pcbs would help.
thanks

[Pingushome]

Originally Posted by jackinnj

After the turn of the year I will put together batches of parts (including the matched transistors.)

In the interim, I'll put together a BOM with the device sizes.

would be intrested in the pcb and bits when they are avaliable pls pm me

[RNMarsh]

Originally Posted by Telstar

JLH amp IC based? the sold u a fake.

A real JLH circuit is in my do do list (after yours, yay!)

I just looked at my comment - some of it didnt come thru.... the JLH was bought off this forum/dyiaudio headphones here. Not IC. Others tried were IC based. There are many to choose from. Some are copies of others work- like JLH. Some are improvements on others work. I am here only to help with my headphone amp... its dirivation is discussed in detail in Linear Audio publication.
In another forum here in dyiaudio I am working on measuring the thd and harmonics and trying to come up with a signal source and thd meter to measure the headphone amp. each time I get something better to test with, the number drops. My older Audio-Precision wasnt up to the task. I now use a ShibaSoku AD725D which can measure directly, to -135db re 1 volt. Then I can add FFT and notch filters to drop that further. Now I need a better signal source and modifying an HP339A as a better (lower distortion) source. All started because I couldnt get an accurate number for my own headphone amp design with the A-P. Its been expensive but fun, too.

Thx-Richard Marsh

[sonidos]

Update -

Working on the psu using LM317 as a pre-regulator per jackinnj's input.

Thanks to one of our DIY mod's I picked up a TEK 475 scope on ebay for $235 and it arrived in great shape. The itch gets more serious! hehehe

[jackinnj]

I've put together some kits of parts for the Marsh headphone amplifier -- you've got two choices: 1) Semiconductors and active components = $54;
2) Semiconductors = $27.50.
This will be sufficient for a pair of amplifiers -- one for each ear.

The JFETs are matched for Idss (that is you get a 2N5460 and 2N5457 which are matched for Idss +/- 0.1mA), bipolar output devices for hfe.



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