Marsh headphone amp from Linear Audio

[mlloyd1]

He mentioned this one:
CC10-0512DF-E
: Detailed Information | Power Supplies - DC-DC Converters | TDK Product Center
I know these are available at Mouser, DigiKey. Maybe other for less ...

mlloyd1

You have a switching power supply that you get dual rails from? Do you mind sharing a schematic or a URL of how you are getting the dual rails please?

 

[gwurb]

He mentioned this one:
CC10-0512DF-E
: Detailed Information | Power Supplies - DC-DC Converters | TDK Product Center
I know these are available at Mouser, DigiKey. Maybe other for less ...

mlloyd1

Ah, I thought the first paragraph was a suggestion (the TDK) and that what he mentioned in the second paragraph was that he was using something else. My bad.

I may source the TDK as a starting point.

Thanks!

 

[jackinnj]

You have a switching power supply that you get dual rails from? Do you mind sharing a schematic or a URL of how you are getting the dual rails please?

Nope -- I am using a conventional dual rail supply, unregulated, with an Amveco transformer. I mentioned the TDK-Lambda as an alternate which, for $26, would seem to do the trick quite nicely!

 

[passive420]

Been listening to the Marsh amp for a week now and can testify it sounds excellent.

Bias drifts slightly between -0.3mV - 0.5mV on each channel but generally very stable and running extremely cool, the 200mm heat sinks are way overkill it appears. Background is utterly silent, zero hiss or hum. No THD measurements yet unfortunately.

Headphones are AKG712 @ 62ohm/105db and Focal Elear @ 80ohm/104db.

The Juma / Prasi Cap Multipliers are working perfectly and highly recommended, very simple and versatile. Rails are at +/-18.5V

Big thanks to Jack for the kit and help and of course to Dr Marsh for a cracking DIY amp. Good job...

 

[donovas]

Could somebody please show me the schematic if even by email?

Theres people who are unable to make international payments and we are left in the dark.

 

[osscar]

Hello.
search in this thread starting from last page - the author of the (RN MARSH) or someone with his permission ( i don't remember) had published the full circuit from article here some time ago, i hope its still there.

 

[jan.didden]

This is a copyrighted article, which is available on the web for € 0.49.
All articles | Linear Audio

Please do not post copyrighted material.

Jan

 

[Pano]

Copyright material will be removed.

 

[gwurb]

I ended up buying

CUT355FF/A TDK-Lambda | Mouser Australia


With that I get some over-voltage and over-current protection. There are cheaper options like
RPT-60C MEAN WELL | Mouser Australia
but I liked the features of the TDK-Lambda

 

[ApolloZhang]

This is a copyrighted article, which is available on the web for € 0.49.
All articles | Linear Audio

Please do not post copyrighted material.

Jan

As I can remember, the article costs like 2.49euro back in 2017

 

[jan.didden]

It is € 0.49 now.

Linear Audio | your tech audio resource

Jan

 

[gwurb]

Yay for the sale. I purchased it too early

 

[jan.didden]

This whole thread is full of builds and tips and findings etc.

Jan

 

[kn0ppers]

With the most important finding being: The JFETs specified are now unavailable

 

[jackinnj]

With the most important finding being: The JFETs specified are now unavailable

Not a problem. You can use LSK170B and LSJ74B -- these will perform quite well.

There are surface mount JFETs as well MMBF -- search on the OnSemi website.

 

[jackinnj]

I sold about 100 "kits of parts" for the Marsh -- all the matched semi's, resistors, potentiometers and the PCB for $27. I still have some if interested.

 

[passive420]

Trying out the Cap MX supply with LT4320 ideal bridge rectifier and Muses volume. Rails are around +/- 22V

Excellent combo. Not enough said about the Marsh design here...

 

[jot23]

Isn't Ideal Diode rectifier best used for higher power demanding devices like Class A speaker amplifiers? Are there any advantages of using such circuit for a low power amplifier?
I recently got a task of building power switching device based on an ideal diode and your post got me thinking.

 

[jan.didden]

The most advantage comes when you use it for (very) low voltages. On a 40V supply, 0.6V diode drop isn't very significant.
But it is on a 3.3V supply!

Jan

 

[jbau]

Richard Marsh has asked me to post his email address for anyone who wants/needs to contact him about the HPA. It is rmarsh@calweb.com . Include the word "Audio" in the subject line so he knows is isn't spam.