2 New DOAs (Discrete Op Amps)

[Carl_Huff]

Hello all,

I have and am stocking two DOAs.  I've built projects with these and like them a lot. 

DOA #1 - Is the SGA-SOA v2 as designed by our own Samuel Groner on an improved double sided PCB designed by me.  I am offering this with Sams full knowledge and support.  This is an excellent all BJT design offering a 'full throated' and robust sound that does not cause ear fatigue over loud and long listening sessions.

DOA #2 -  Is the classic MOX JFET Op Amp.  This one features a matched FET front end pair.  I have versions that use (NOS) Toshiba SK389s,  LSK389s from Linear Systems and the (NOS) NEC uP686 parts.  This DOA affords the intimacy and detail that you can expect from a classic FET design.

I have put up a web page for those that want to further explore or even purchase these DOAs.  https://kadproducts.com/

I have both unpopulated PCBs and finished and tested modules.  Both are built using the classic PRO 2520 pin sockets and can be swapped into existing legacy gear designed for older DOAs.  Both the BJT and FET DOAs are unity gain stable.  Both sound great! 

Here is a PIC of a pair of Sam's DOAs used in a headphone amplifier.  The headphone amplifier is from Sams application notes for his first version DOA.  Details for this project can be found on his website.  http://www.nanovolt.ch/resources/discrete_opamps/index.html

I also have a phono amp project and a full blown audiophile preamplifier based around these modules.  If there is enough interest I could make the details of these designs available.

Have I stirred an interest?  Or am I the last old timer that sees value in discrete op amps?

 

[bruno2000]

I'm interested!
Best,
Bruno2000

 

[Potato Cakes]

More different DOAs to build? When will it end?!


Thanks!

Paul

 

[CJ]

when do the Melcor boards get here?  jus sayin, wtf, over?

 

[Carl_Huff]

Humble beginnings  but a start ...        https://kadproducts.com/

 

[living sounds]

Hi Carl,

your PSU looks interesting, is there a BOM I can download? Do you ship to Germany?

Thanks!

 

[Carl_Huff]

This is a nice power supply!  I've tried many others over the years but keep coming back to this one.  It's low profile too, fitting easily into a 1U chassis.

I ship to Germany, no problem.  I send the BOM and schematic when a purchase is made.  The active devices are 2 x NE5534s, a BD139/140 pair and a general purpose pair of BC550/560s.  The rest amounts to common capacitors, resistors and heastsinks.  I am currently testing (beating up??) a version of the described 'Series Regulated Power Supply' that is adjustable. 

It's identical to the  fixed voltage version shown here: https://kadproducts.com/products/low-noise-power-supply

With the addition of 2 multi turn pots that are physically next to the Phoenix voltage tap block.  The price will be same as the existing version.  The new pots allow you to exactly adjust your target voltages from +/-9 volts to +/-24 volts.

 

[Carl_Huff]

Hi Carl,

your PSU looks interesting, is there a BOM I can download? Do you ship to Germany?

Thanks!

A quick point ...

The power supply pictured and what I have been shipping is intended for use on 115v mains.  It can be easily modified for 230 volt mains, however the best solution would be for me to fab PCBs that target 230 volt mains.  I am willing to do that.  Please let me know if there is an interest.

 

[Carl_Huff]

Nice to see your work Carl.

Thank you!  I've been doing this for a while and have accumulated some very good building blocks.  I wanted to share them with others to see what magic toys they can conjure using them.

 

[rafafredd]

Are you selling these? What's the price???

 

[living sounds]

Sounds great! I would definitely be interested in a few of these. Regarding the BOM I was mainly wondering about trafo and if I can source fitting ones locally.

Can you elaborate more about the specs of the PSU, output current, noise etc.? Thanks!

 

[Carl_Huff]

Are you selling these? What's the price???

Yes!  The are $96 built and tested. They are here:  https://kadproducts.com/products/low-noise-power-supply

I also sell just the PCB (double sided, plate thru and silk screened)  for $8 each or 3 for $20. 

 

[Carl_Huff]

Sounds great! I would definitely be interested in a few of these. Regarding the BOM I was mainly wondering about trafo and if I can source fitting ones locally.

Can you elaborate more about the specs of the PSU, output current, noise etc.? Thanks!

The transformer is specified as an AMGIS 18v 15vA dual transformer #L01-6354. 

I buy them from digikey: https://www.digikey.com/product-detail/en/amgis-llc/L01-6354/TE2254-ND/2137084

As to trusted specs and measurement, I have nothing recent.  That's probably an item that I should add to my 'ToDo list '.  The design is old school series regulated darlington pair using very common parts.  I've been building these into projects for years.

The transformer as rated can sink nearly 500mA on it's secondary at 115 volts (less on 230).  The downstream parts are heatsinked and should be easily able to deliver the current, however I conservatively rate the power supply as capable of delivering 250mA.

Here is what the raw PCBs look like.

 

[90scaraudio]

The transformer is specified as an AMGIS 18v 15vA dual transformer #L01-6354.

I buy them from digikey: https://www.digikey.com/product-detail/en/amgis-llc/L01-6354/TE2254-ND/2137084

As to trusted specs and measurement, I have nothing recent. That's probably an item that I should add to my 'ToDo list '. The design is old school series regulated darlington pair using very common parts. I've been building these into projects for years.

The transformer as rated can sink nearly 500mA on it's secondary at 115 volts (less on 230). The downstream parts are heatsinked and should be easily able to deliver the current, however I conservatively rate the power supply as capable of delivering 250mA.

Here is what the raw PCBs look like.

Is there any chance I could purchase one of your boards, if you have any left? And if you have one of these AMGIS L01-6354, Digikey is out of stock.
Please let me know. Will pay with PayPal.