50w Single-Ended BAF2015 Schade Enabled

[jostwid]

IRLB3813

Thank you Circlomanen for the low voltage Mosfet hint.
It was worthwhile to change from IRFP240 to IRLB3813. They operate at their best conditions and are sonically speaking superior in this application.

I still use "Genergs" circuit.

B+ 19.4V
A = 1.23
Dissipation 24Watt / channel
Voltage gain 20db

I measured a max of 9.08V out into 8 Ohm
This amp is plenty enough for my home listening
I wish i had an ACA at hand to compare

 

[Circlomanen]

Thank you Circlomanen for the low voltage Mosfet hint.

I got this idea from Nelson Pass article http://www.firstwatt.com/pdf/art_zen_redux.pdf Zen amp redux.

The IRLB3813 is a nice little device. Very powerful within its quite limited voltage rating.

I still use "Genergs" circuit.

I could not find this?! Do you have a link to it? I would like to see the schematic you used.

Cheers,
Johannes

 

[generg]

I think it could be here....
http://www.diyaudio.com/forums/pass...ded-baf2015-schade-enabled-6.html#post4706046

 

[jostwid]

Almost

The schematic was posted by Generg in BAF Coverage page 57 posting #564.
It is more simple than the above version but it does the trick.

http://www.diyaudio.com/forums/pass-labs/280950-baf-2015-coverage-57.html

 

[Zen Mod]

you need to link exact post (hover across # , upper right corner of post,copy link)

preferable (by forum software) setting is 50 posts per page , and you obviously doesn't have that , so your page isn't the same as someone else's

 

[jostwid]

Ok ZenMod

hopefully got it right this time...
http://www.diyaudio.com/forums/pass-labs/280950-baf-2015-coverage-57.html#post4577324

in case i did not here is a picture

 

[Pascal Nguyen]

A double face of my amp

Hi all,
I've been in this forum for a month, quite a period of time to catch up with DIY audio that was dormant for 40 years, lot of things to catchup and to learn...and you guys in this forum in particularly Mr Pass and Johannes have done a tremendous work to teach me how to be on my own again.

Today I would like to share with you all, my IRFP7430 amp, disclosing a tiny switch that could help me to listen in two modes.

Mode Pentode, the switch disconnects a feed back path from the speaker output, let the amp functioning alone as a class A with CCS.

Mode Triode, taking a Positive Current Feedback to tame the 7430 as a triode.

Well, I never experience such a "phenomena" in that magnitude, in the PCF selection, the audio is so sweet and so pure, one could say "sterile music".
To the other extreme, I can disable that function to listen to "dirty music" or one can say "vivid music".

I have uploaded a video clip to share with you my excitement.

Cheers
Pascal

https://youtu.be/tfM3nDKFAIE

 

[wdecho]

Ok ZenMod

hopefully got it right this time...
http://www.diyaudio.com/forums/pass-labs/280950-baf-2015-coverage-57.html#post4577324

in case i did not here is a picture

View attachment 575523

Has anyone built this circuit? The schematic below. I would love to hear opinions on sound.

On the subject of the BAF 2015 schade amp I am amazed there has been so few if any builds of the big amp. If I owned less than 90db speakers I would have jumped right on this build. Having built the V-fet amplifier I can say there is nothing like a SIT amplifier. If one needs 50 watts of power with a SIT sound this is it. Reading some of the info at Passlabs I believe Nelson has given away some his secrets for one of his great amps. It sounds to me like greedy boyz diy'ers can build one of his big amps now.

 

[Nelson Pass]

It's a simple functional design that works. Remember that for low distortion
and wide bandwidth it wants a low impedance source, and for stability at
low frequencies that source wants to be DC coupled. A simple push-pull
Jfet buffer will do that job.

 

[wdecho]

It's a simple functional design that works. Remember that for low distortion
and wide bandwidth it wants a low impedance source, and for stability at
low frequencies that source wants to be DC coupled. A simple push-pull
Jfet buffer will do that job.

 

[woody]

Has anyone thought about having a small board just for that current source. I know it can be built point to point but I would prefer a little board as it looks neater.

 

[Pascal Nguyen]

Has anyone built this circuit? ...

https://youtu.be/J9WCaXorwdA

with IRFP7430 available at hand.

Cheers
Pascal

 

[wdecho]

https://youtu.be/J9WCaXorwdA

with IRFP7430 available at hand.

Cheers
Pascal

I watched the video. Very nice and I bet it sounds fantastic but from what I saw on the video you used a different schematic than the one I was asking about. I would like to read more about what you built if you point me to the info.

 

[wdecho]

I watched the video. Very nice and I bet it sounds fantastic but from what I saw on the video you used a different schematic than the one I was asking about. I would like to read more about what you built if you point me to the info.

I just thought I would add that in the video I notice the input transformers but the schematic shown in the video does not have input transformers.

 

[Circlomanen]

The mighty IRFP7430 does not need any schade feedback to "triodiefy" the transfer curves. It has "triodity" in abundance all by itself.

I would guess some schade-feedback would tame the curves down a bit. When I tested transformer-based schade feedback with a somewhat less "triody" and wild IRLP3034 it only sounded cleaner and smoother with less of the typical character of the IRLP3034.

I don't like global negative voltage feedback. It sucks! (life and soul out of the reproduction of music).

A Schade-feedbacked Ixys or IR normal pentodish mosfet does sound much better then without Schade feedback.

My bastode Schade feedback Ixys IXTK100N25P sounds quite similar to the basic character of the IRFP7430. Much cleaner and smoother but somewhat laid back and half-hearted.

If an IRFP150 is Diana Krall, then the Schade feedback Ixys IXTK100N25P is Metallica and the IRFP7430 is Meshuggah having a spectacular acid trip, as a comparison.

Cheers,
Johannes

 

[Soundhappy]

What type of PSU we need for Schade 50W ?
Capacitors i have is rated 65VDC max surge.
The photo above is all sit's on his B-1 schematic.
Greetings 🙂

 

[needtubes]

What type of PSU we need for Schade 50W?

Schematic on page 2 shows you need 60V at 3.2A per channel of the 50W Schade amp.

 

[Soundhappy]

Schematic on page 2 shows you need 60V at 3.2A per channel of the 50W Schade amp.

Yes ok and i can simulate all types of 60V psu schematics with software.
Anyway i don't know which is the best and more appriopriate for Schade 50 W.
First i try with lab stabilised psu's.
Search to complete components psu bill of materials to affort them with IXFN hockey pucks
from Mouser at one deal & shipping.

 

[vdi_nenna]

Stupid question regarding resistance to ground. Can I put the resistance on the SE amp's input side or does it have to be on the preamp outputs?

I have triode tubes on the brain right now. I heard a 520B last night. It's around 25w SE triode. Simply amazing. Only problem is they are $900 a pair.

520B-V2 and 520B-V3 Data sheet Emission Labs.

I'm curious to see if this SE 50w Schade can sound similar. I'm still going for 1/2 the power, unless there is a penalty for going for 1/2 measures.

 

[vdi_nenna]

if I put it on the preamp side, it will raise the output impedance and that's not good.