Geek said:
I really do need to get the rest of the SEWA parts together & get them over to you.
Chassis will have to wait for the thaw.
Question. To be an adequate heat-sink for a single channel (18 VAC supply), how long would a piece of 8" square 1/2" wall aluminun tube need to be? If the answer is too large a number, we'll have to consider bolting on helper heatsinks.
dave
Re: Re: Re: Re: Re: 150Vdc SS regulated PSU
Sounds good, Zen Mod
I would have to say it is not always easy to define what is shunt or series.
If you have a look at my
Tutorial made especially for Tyimo
and a final design of a 150 Volt regulator
http://www.diyaudio.com/forums/attachment.php?s=&postid=1103164&stamp=1168446341
... it is not as easy as to say this is a true Shunt regulator.
Because if looking from the outside, pins,
TL431 can be regarded as a Variable, Adjustable ZENER. ( 2.5V - 36V )
But looking at internal circuit, with many Transistors!
it may be seen it operates not very different to a series regulator, really.
lineup
Zen Mod said:
Sounds good, Zen Mod
I would have to say it is not always easy to define what is shunt or series.
If you have a look at my
Tutorial made especially for Tyimo
and a final design of a 150 Volt regulator
http://www.diyaudio.com/forums/attachment.php?s=&postid=1103164&stamp=1168446341
... it is not as easy as to say this is a true Shunt regulator.
Because if looking from the outside, pins,
TL431 can be regarded as a Variable, Adjustable ZENER. ( 2.5V - 36V )
But looking at internal circuit, with many Transistors!
it may be seen it operates not very different to a series regulator, really.
lineup
Tube Preamp for SEWA noise problems
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 pramp has also insulated in and outputs and no earthing and grunding to 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??
I will try to remove the grunding connection between the case in the SEWA.
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
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 pramp has also insulated in and outputs and no earthing and grunding to 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??
I will try to remove the grunding connection between the case in the SEWA.
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
It sounds to me as if you have a ground loop between the preamp and the SEWA. Grounds loops tend to sound much more complex than simple power supply hum and quite often have a rooshing - pulsing component. This probably is going back through the mains leads.
Have you tried back to back diodes with a 0.47uf cap and 100R resistor, all in parallel, between your circuit ground and the mains earths. Try this in both the preamp and poweramp.
Shoog
Have you tried back to back diodes with a 0.47uf cap and 100R resistor, all in parallel, between your circuit ground and the mains earths. Try this in both the preamp and poweramp.
Shoog
Hi!
Here are the variations I tryed today:
-Tubpre with PSU negative rail to case via 1Meg resistor bridged with a 0.047uF film cap + SEWA PSU grund connected to case via diode bridge (a'la Nelson Pass) and to mains safety earth = Noise!
- Tubpre with PSU negative rail to case via 1Meg resistor bridged with a 0.047uF film cap + SEWA without PSU-case connection, only case to the mains safety earth connection. = More noise!!
-Tubpre without grunding and connecting to the mains safety earth + SEWA PSU grund connected to case via diode bridge (a'la Nelson Pass) and to mains safety earth = Noise!
-Tubpre and SEWA without grunding to case and not connected to the mains safety earth = Noise!
-Tryed different RCA cables, wall connectors, earthed, not earthed, mooved the system away from another electric gears = Noise!
I measured the noise (output voltage) and it is ca. 26mV Vac.
All my case are free from voltages. In and outputs are totaly isolated.
-I tryed the Tubpre with PSU negative rail to case via 1Meg resistor bridged with a 0.047uF film cap + Aleph5 PSU grund connected to case via 10R 20W resistor and to mains safety earth = no noise!!!!!
- SEWA grunded as I wrote + BOZ grounded as designed by Nelson Pass = No noise!!!!!
So, I going to be crazy!!!!
I am afraid that I have to give a new name for the tubpre:
Tube Preamp for NOT SEWA
Any idea????
Here is the tubepreamp. I built without the input cap and the volume pot.
Tyimo
Here are the variations I tryed today:
-Tubpre with PSU negative rail to case via 1Meg resistor bridged with a 0.047uF film cap + SEWA PSU grund connected to case via diode bridge (a'la Nelson Pass) and to mains safety earth = Noise!
- Tubpre with PSU negative rail to case via 1Meg resistor bridged with a 0.047uF film cap + SEWA without PSU-case connection, only case to the mains safety earth connection. = More noise!!
-Tubpre without grunding and connecting to the mains safety earth + SEWA PSU grund connected to case via diode bridge (a'la Nelson Pass) and to mains safety earth = Noise!
-Tubpre and SEWA without grunding to case and not connected to the mains safety earth = Noise!
-Tryed different RCA cables, wall connectors, earthed, not earthed, mooved the system away from another electric gears = Noise!
I measured the noise (output voltage) and it is ca. 26mV Vac.
All my case are free from voltages. In and outputs are totaly isolated.
-I tryed the Tubpre with PSU negative rail to case via 1Meg resistor bridged with a 0.047uF film cap + Aleph5 PSU grund connected to case via 10R 20W resistor and to mains safety earth = no noise!!!!!
- SEWA grunded as I wrote + BOZ grounded as designed by Nelson Pass = No noise!!!!!
So, I going to be crazy!!!!
I am afraid that I have to give a new name for the tubpre:
Tube Preamp for NOT SEWA
Any idea????
Here is the tubepreamp. I built without the input cap and the volume pot.
Tyimo
Attachments
There is this swedish guy who have made this exelent guide on grounding.In SWEDISH...but look at the pictures and se,very important ang how to break gound loops with resistors and more.
http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=57302&whichpage=2
Have you isolated the input RCA frpm the chassie?Grounded the input ,at the input,not by the PSU?
And did you say you had to low gain?
http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=57302&whichpage=2
Have you isolated the input RCA frpm the chassie?Grounded the input ,at the input,not by the PSU?
And did you say you had to low gain?
Hi Ryssen!
Thanks for the link.
Yes!
Not. Tomorow I will try it. It is my last hope...
What do you mean?? The preamp has very much gain. More than enough!
I think the most strange thing is that the preamp works very well with many different amps, but NOT with the SEWA!!
In the same system with same components, same metal case and same grunding method why has it noise only with the SEWA ?????
Tyimo
Thanks for the link.
Yes!
Not. Tomorow I will try it. It is my last hope...
What do you mean?? The preamp has very much gain. More than enough!
I think the most strange thing is that the preamp works very well with many different amps, but NOT with the SEWA!!
In the same system with same components, same metal case and same grunding method why has it noise only with the SEWA ?????
Tyimo
Heureka!!! I found it!!!!
After a crazy half day testing I found the best grounding-earthing variation!!! I tried more than 16 variation of grunding and the last was the good.
In tubepre the input RCAs are connected to the case and the case to the mains safety earth.
In the SEWA the PSU grund was connected via diode bridge to the case and to the mains safety earth.
I tried to connect the tubepre input RCAs via 10R+220nF to the case, but it was not better the without it.
So, now the noise is on acceptable level. Not the very best but good.
I am very happy and enjoy to listening music on the Geek's Tubepre-SEWA combo!!
However I didn't understand why I had this grunding problem, because until now I built more then a dozen amps and preamps and never had anyproblem with them!
Now only one question:
I was re-reading all my articles about earthing and I found something mistakable thing with the diode bridge coupling.
Mr. Pass wrote:
Mr. Rod Elliot wrote:
As it is in the next attached image.
So, Who has true?????????????????????????????
Maybe I should change my psu grunding in my SEWA like Rod Elliot says?
And one more info: Geek's tubepreamp is so nice sounding....... 
Thanks Geek!
Greets:
Tyimo
After a crazy half day testing I found the best grounding-earthing variation!!! I tried more than 16 variation of grunding and the last was the good.
In tubepre the input RCAs are connected to the case and the case to the mains safety earth.
In the SEWA the PSU grund was connected via diode bridge to the case and to the mains safety earth.
I tried to connect the tubepre input RCAs via 10R+220nF to the case, but it was not better the without it.
So, now the noise is on acceptable level. Not the very best but good.
I am very happy and enjoy to listening music on the Geek's Tubepre-SEWA combo!!
However I didn't understand why I had this grunding problem, because until now I built more then a dozen amps and preamps and never had anyproblem with them!
Now only one question:
I was re-reading all my articles about earthing and I found something mistakable thing with the diode bridge coupling.
Mr. Pass wrote:
As it is in the attached image.
Mr. Rod Elliot wrote:
He use the DC legs of the bridge to connect to the circuit!!!!!
As it is in the next attached image.
So, Who has true?????????????????????????????
Maybe I should change my psu grunding in my SEWA like Rod Elliot says?
And one more info: Geek's tubepreamp is so nice sounding.......
Thanks Geek!
Greets:
Tyimo
Attachments
Swedish mumbo jumbo...
An externally hosted image should be here but it was not working when we last tested it.
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