Marsh headphone amp from Linear Audio

Hello,

The Morgan Jones article is in Linear Audio Volume 5, April 2013.

I have a couple of Signal A41-25-16 power transformers on the shelf, rectified they will put out about 24VDC. I will use these power transformers with the AudioWind regulators linked in a previous post. I am skipping using the Quasimodo snubber/zobel and come back if there is an issue.

There is an impedance plot for the Signal A41-25-16 posted below.

Also on the shelf are a couple of Silent Switchers, they will do 150ma at +- 15 VDC, that will drive a single side of the Marsh HPA.

Thanks DT

Hello All,

Today looking back at this thread I see that I made a mistake.

Take a look back at post #1474, I called out a regulator, Audiowind A2007 and a transformer.

I see in the photo in post #1493 that I had one of the transformer leads under the wrong screw terminal on the regulator.

I am going back and taking a closer look at the Marsh Diamond and compound amplifiers and buffers. I bought a new batch of JFETs to play with.

Thanks DT
 
What value of volume potentiometer is recommended for amplifier?

And which power supplys works well with the amplifier?

Hi
Mr Marsh used a 15v psu at one time 12 to 20 volt is apparently ok providing caps are rated for it. I use 15v+/-. Any good quality one will do no need for anything too exotic. I used one that was on Dirty PCs years ago
From memory I think it’s a 100ohm pot but I may be wrong and it may be 50 ohm. If you get low vol try the other pot
Hope that helps
 

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Hello,

Is there any possible replacement for 2N5457 (MMBF5457) and 2N5460 (MMBF5460)? Those are globally no stock at all, and I couldn't find any good alternatives yet.

Mouser have SMP5460 in stock from InterFET, but only limited to P type....
Hi withmatt,

Try member @jackinnj, the initiator of this thread. He has been supplying boards, matched transistors and, I believe, most other parts with Mr. Marsh's blessing. He may have some left.

Regards,
Rob
 
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Hi withmatt,

Try member @jackinnj, the initiator of this thread. He has been supplying boards, matched transistors and, I believe, most other parts with Mr. Marsh's blessing. He may have some left.

Regards,
Rob
Hello Rob,

Thanks for quick support.

However, I would like to design own PCB to fit into my platform design, which requires 2N5457/5460 or equivalent.
Buying old JFET is really challenging nowdays..

Thanks,
Matt
 
I will have a small window of time to get PCB's and kits out around June 1. USPS has increased postal rates both within the US and UK, Canada etc. thus shipping to Canada $15, to UK $18. PCB's are $3 and have two amplifier circuits, complete kits including semi's, diodes, and passives $40 (includes PCB). I will invoice you if you send me your PayPal address.
 
Hi

Thanks for getting back to us Jack.

Is there a way to get the Volume 3 of "Linear Audio" article so I can read more about this HA. The only place I found it was Amazon at $25 for the complete Volume 3.

I’d like to know the current requirements is it +/- 15Vdc at 150mA per channel or less ?
Ideally I’d like to use a 19Vdc laptop supply, is there a well known (not noisy) way to get from +19Vdc to dual polarity +/-15Vdc supply?

Thanks
Eric