O.K. I tell you, but please don't injure me.....!!
I would like to try to build an OTA with Output transformer.
I told you it is perverse.......
The reason is:
I have heard so many oppinions pro and contra about output transformers, that now I would like to test it myself.
I now the sound of the direct coupled and also the capacitor coupled amps, but not the transformer coupled. So I thought on the OTA....
Greets:
Tyimo
I would like to try to build an OTA with Output transformer.
I told you it is perverse.......
The reason is:
I have heard so many oppinions pro and contra about output transformers, that now I would like to test it myself.
I now the sound of the direct coupled and also the capacitor coupled amps, but not the transformer coupled. So I thought on the OTA....
Greets:
Tyimo
O.K. I am on it!
Should I ask again how did you like the FQA33N10 fet?
I think it could be a good substitute of the IRFP series...
It has
Gfs: 23 S /40V-18A/
Ciss:1150 pF
Rjc: 0.92, but 175C max. junction temperature rating
One more question:
did you make a PCB for your nice Atlantis RIAA preamp??
Greets:
Tyimo
Should I ask again how did you like the FQA33N10 fet?
I think it could be a good substitute of the IRFP series...
It has
Gfs: 23 S /40V-18A/
Ciss:1150 pF
Rjc: 0.92, but 175C max. junction temperature rating
One more question:
did you make a PCB for your nice Atlantis RIAA preamp??
Greets:
Tyimo
Hi!
I built the Tub Preamp for SEWA (designed by Geek, thanks!) and I have some strange noise problem.
When I use the tubepre with the SEWA I have a noise and when I turn on the CDplayer the noise getting louder 2-3 times.
It is not a "hummm". It is something like "brizzzz" noise around couple of hundred Hz.
I tryed the tubpre with another DIY and commercial amps and most of time there was not noise!
So, here is the test:
-With SEWA: high, unacceptable noise.
-With Zen Lite: very little noise, acceptable level.
-With Aleph5. very little noise, acceptable level.
Every power amp has metal case and grounding connections with the case and the mains safety earth. Like in the attached image. RCAs and Outputs are insulated.
My preamp has also insulated in and outputs and no earthing and grunding to the case.
I tryed to ground the preamp with: PSU negative rail to case via 1Meg resistor bridged with a 0.047uF film cap, but the result was the same. With the SEWA even worse!
In the test I used the same components and cables and wall connector.
-I tryed the SEWA without the mains safety earth connection, but the noise was still there!!
-In another system with ZV9: totaly-deadly quiet!! This amp is not earthed and has wooden case.
-With a commercial Pioneer amp also deadly quiet! It is not earthed too.
-With another ZV9 in metal case and earthed was noise again!
So, I don't know what could be the problem.
Basically my SEWA is working perfect with SS preamps like BOZ and BOSOZ.
I am affraid that the problem is in (or with) my SEWA amp. May be some impedance problems or oscillation??
Next I will try to remove the grunding connection between the case in the SEWA.
Questions for the tubpre:
Need I use the 50K input pot? I use the output pot in my CDplayer.
Need I use the 2.2uF input cap??
BTW: The tube preamp has superb sound! It can easy drive the mosfet amps. Except my SEWA!!
Greets:
Tyimo
I built the Tub Preamp for SEWA (designed by Geek, thanks!) and I have some strange noise problem.
When I use the tubepre with the SEWA I have a noise and when I turn on the CDplayer the noise getting louder 2-3 times.
It is not a "hummm". It is something like "brizzzz" noise around couple of hundred Hz.
I tryed the tubpre with another DIY and commercial amps and most of time there was not noise!
So, here is the test:
-With SEWA: high, unacceptable noise.
-With Zen Lite: very little noise, acceptable level.
-With Aleph5. very little noise, acceptable level.
Every power amp has metal case and grounding connections with the case and the mains safety earth. Like in the attached image. RCAs and Outputs are insulated.
My preamp has also insulated in and outputs and no earthing and grunding to the case.
I tryed to ground the preamp with: PSU negative rail to case via 1Meg resistor bridged with a 0.047uF film cap, but the result was the same. With the SEWA even worse!
In the test I used the same components and cables and wall connector.
-I tryed the SEWA without the mains safety earth connection, but the noise was still there!!
-In another system with ZV9: totaly-deadly quiet!! This amp is not earthed and has wooden case.
-With a commercial Pioneer amp also deadly quiet! It is not earthed too.
-With another ZV9 in metal case and earthed was noise again!
So, I don't know what could be the problem.
Basically my SEWA is working perfect with SS preamps like BOZ and BOSOZ.
I am affraid that the problem is in (or with) my SEWA amp. May be some impedance problems or oscillation??
Next I will try to remove the grunding connection between the case in the SEWA.
Questions for the tubpre:
Need I use the 50K input pot? I use the output pot in my CDplayer.
Need I use the 2.2uF input cap??
BTW: The tube preamp has superb sound! It can easy drive the mosfet amps. Except my SEWA!!
Greets:
Tyimo
Attachments
You mentioned output transformer - here is some inspiration with information about transformers
Well, maybe you only need a small linetrafo on Sewa inputs, but I cant say, just a blind guess
http://www.audiophonics.com/index.html
Well, maybe you only need a small linetrafo on Sewa inputs, but I cant say, just a blind guess
http://www.audiophonics.com/index.html
Hi Mads!
I think I solved the problem, but I am still confused. Please read my post in the Tubpreamp for SEWA thread.
http://www.diyaudio.com/forums/showthread.php?postid=1143355#post1143355
Here is the Tubepre schematic.
Greets:
Tyimo
I think I solved the problem, but I am still confused. Please read my post in the Tubpreamp for SEWA thread.
http://www.diyaudio.com/forums/showthread.php?postid=1143355#post1143355
Here is the Tubepre schematic.
Greets:
Tyimo
Attachments
Tyimo said:
When you setup this circuit, Tyimo:
What voltages you have?
1. Where schematic says: 130V
2. Where schematic says: 100V
To get the actual current running in TUBE stage
we take: (voltage1 - voltage2) /10.470kohm
.... because this is the voltage across these 2 resistors
I dont know what trouble you have?
Isnt this tube amplifier working as it should ...
Regards
lineup
Hi Lineup!
The Tubpreamp is working as it should. Everything allright in the circuit, but I hade some serious grounding noise problem with my Tubepre and the SEWA.
Please read this:
http://www.diyaudio.com/forums/showthread.php?postid=1142586#post1142586
http://www.diyaudio.com/forums/showthread.php?postid=1142684#post1142684
I solved the problem, but I am still confused and I didn't understand why I had this grunding problem, because until now I built more then a dozen amps and preamps with the same grunding-earthing method and never had anyproblem with them!
The most strange thing is that the preamp worked very well with many different amps, but NOT with the SEWA and the SEWA worked very well with another preamps (BOZ, BOSOZ).
In the same system with same components, same metal case and same grunding method why had it noise only with the SEWA?
http://www.diyaudio.com/forums/showthread.php?postid=1143355#post1143355
Now I have only one question:
How should I connect the diode bridge to the circuit grund?
DC legs to Earth - AC legs to the circuit? Nelson Pass
AC legs to Earth - DC legs to the circuit? Rod Elliot
Greets:
Tyimo
The Tubpreamp is working as it should. Everything allright in the circuit, but I hade some serious grounding noise problem with my Tubepre and the SEWA.
Please read this:
http://www.diyaudio.com/forums/showthread.php?postid=1142586#post1142586
http://www.diyaudio.com/forums/showthread.php?postid=1142684#post1142684
I solved the problem, but I am still confused and I didn't understand why I had this grunding problem, because until now I built more then a dozen amps and preamps with the same grunding-earthing method and never had anyproblem with them!
The most strange thing is that the preamp worked very well with many different amps, but NOT with the SEWA and the SEWA worked very well with another preamps (BOZ, BOSOZ).
In the same system with same components, same metal case and same grunding method why had it noise only with the SEWA?
http://www.diyaudio.com/forums/showthread.php?postid=1143355#post1143355
Now I have only one question:
How should I connect the diode bridge to the circuit grund?
DC legs to Earth - AC legs to the circuit? Nelson Pass
AC legs to Earth - DC legs to the circuit? Rod Elliot
Greets:
Tyimo
Hi Babowana!
Yes, it was a strong Bzzzzzz and not an ordinary hummmmm!
http://www.diyaudio.com/forums/showthread.php?postid=1143355#post1143355
Tyimo
What do you suggest? What kind of cable, wher and how to connect etc.??
Greets:
Tyimo
Yes, it was a strong Bzzzzzz and not an ordinary hummmmm!
http://www.diyaudio.com/forums/showthread.php?postid=1143355#post1143355
Tyimo
What do you suggest? What kind of cable, wher and how to connect etc.??
Greets:
Tyimo
Tyimo said:
1. Build a normal BRIDGE RECTIFIER = 4 diodes.
2. Connect V- to ground
3. Connect V+ to V+
This is for a single ended supply.
You can see this in my single ended Class A Power Buffer Amplifier:
Jerluwoo MJ21194 Output Stage - by Lineup Audio Lab
Post #79, with comments and test results
http://www.diyaudio.com/forums/showthread.php?postid=1036543#post1036543
Circuit here:
http://www.diyaudio.com/forums/attachment.php?s=&postid=1036543&stamp=1161488807
Regards
lineup
Lineup Audio Lab productions, for Internet
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