Hi,
The same, only better....
Anyway, jokes aside, what we're trying to tell you is to first get the basics right then, and only then we'll put the icing on the cake.
Sincerely,
Ok thx. I thought you were serious not visiting the land of elks and ABBA
I meant more is it the same like in signalpath this cap. I usually hear knight day between elcos and film.
OK, thanks.
You should not lead by appearances, I'm just a TV repairman.
By noise I mean thermal noise, that hiss on tweeters, in this case its max would be at mid volume pot, near 3 o'clock.
Plastic capacitors are almost linear devices, its dielectric hysteresis curve has very low area, and is almost a straight line, especially Teflon, and MKP, if "cap rolling" give good results your design is questionable. IMHO
BTW, by quality and lasting the best for me are Siemens MKVs, and MKPs, Wima and ERO MKPs, unfortunately Siemens no longer makes capacitors
In terms of sound, even a cheap Epcos MKP is indistinguible, even more, most expensive "audio grade" capacitors are often inductive.
Hi,
The best way to deal with those hyperactive xformers is to put them outboard in a separate casing and use an umbilical to connect them to the preamp.
http://cubesfortubes.de/?lang=en
As for film caps, sure. Just remember that electrolytics are made for filtering, once that's done and ripple free you can use film caps in most places.
Ciao,
The best way to deal with those hyperactive xformers is to put them outboard in a separate casing and use an umbilical to connect them to the preamp.
http://cubesfortubes.de/?lang=en
As for film caps, sure. Just remember that electrolytics are made for filtering, once that's done and ripple free you can use film caps in most places.
Ciao,
Hi,
Just for info, Epcos was originally designed and manufactured by Siemens.
They were too good so they sold off that branch.
Back the days we used quite a lot of Epcos MKV (powerfactoring) caps in psus for audio.
Ciao,
Indeed, they were the same Siemens group, not today, Epcos is now part of TDK group, and quality lowered a bit, as price did, I didn't see Epcos MKV since that time, what a pity.
Edit: Faradostalgia
Last edited:
I replaced the 1Meg on output with 100K like Franki said I could test and it seems to "burn" off some gain/energy. Sound is a bit dark now (?)
What about the input?
When it came from china it was 10K both ways but after cap (input) and before cap at output... Some older design of same board like i think my finnish friend showed earlier they hade only 100K on the input after cap.
What were they thinking? It seems like they do no good as a leak resistor at wrong place. Or maybe it was to burn of some gain?
What about the input?
When it came from china it was 10K both ways but after cap (input) and before cap at output... Some older design of same board like i think my finnish friend showed earlier they hade only 100K on the input after cap.
What were they thinking? It seems like they do no good as a leak resistor at wrong place. Or maybe it was to burn of some gain?
Ok. You thinking 100k on the input too as a leakresistor?
Been looking around on different schematics (tubeamps, preamps) and most of them have 1M both on input and output. Seems like a "golden rule"
But what you says make sense.
So what you mean is if i know have bypaased cathode i need a gridstopper on top triode too?
No, for bypassed SRPP, plate resistance of the bottom triode acts as grid stopper for the top triode, for unbypassed version, the "natural" grid stopper for the top triode is even bigger.
Conclusion: SRPP topology doesn't need grid stopper for the upper triode.
I have some 3mm RED/BLUE/GREEN leds home. Does it have to be red?
So it actually gonna light up or to low voltage (1,7V)?
What is the difference compared to say MKP in this position?
Thx
Ok understood. At the moment i'm playing with gridstopper (330ohm) and unbypassed. Tomorrow thinking trying LED
I must confess that your preamp changes every so often, and I'm a little dizzy with that, but assuming that you are using cathode resistors of about 330 Ω at a current of about 5 mA, the voltage drop is about 1.65V, ideal for a red LED.
With the LED you can avoid another highpass filter.
6N3P has a tranconductance of about 6 mA/V at about 9 mA of plate current, at 5 mA, transconductance is even smaller, so you don't need a grid stopper.
Also SRPP is rock stable, one more reason for avoid grid stoppers and the noise penalty that involves.
Yes, you can use 1/4 W resistors, but as a general rule, I use 1 W carbon-film, the cheapest ones !
Greetings Fm Singapore,
This thread had really expanded both my knowledge and insight in DIY Audio.
Salute to all experts for your experiences and willingness to share.
My salute to Max who is so determined to "perfect" your preamp.
I had recently also began a tube SRPP preamp project after i got from a Chinese supplier of the attached preamp, same it is also based on the Chinese 6N3 tubes and a 6Z4 rectifier. I had custom made a transformer of 180v-0-180v, 6.3v(1A) and a 8v(1A) output as required by the board.
As the board came assembled I simply attached the transformer and i loved the sound of the pre-amp. After 2 weeks i felt there is a need to case up the board and transformer thus i began to de-solder the tube sockets, input, output and the volume pot.
I used Beldan silver plated cables for the tubes extension onto the top of chassis and Canare signal cables for both input(2x input with selector switch) and output.
I had also got a aluminium case for the transformer.
Having all holes drilled and connection made(checked). Hoping to hear (if not better) the same SQ i was blasted away with you know what! HUMS!!!!
As i began researching for answers and ways to overcome the HUM i came across you guys.(thank God).
Can you kindly advised me the following?
1. In SG we have 230V AC mains with "live" ,"Neutral" and "Earth".
What is the difference between the "earth" and "ground" ?
Mr Shoog had indicated about the “star ground” principles,
Mr. Shoog.
Glad to hear it worked out.
Now going back and paying attention to star grounding should eliminate the last of the hum you have lingering about. Its most important to not have your small signal (input RCA and grid stoppers) tied to anything high power ie your PSU caps. Tie all your small signal grounds together and then take a thin wire to your high current grounds in your power supply. Finally a big wire straight from your high current ground to your socket safety ground.
Great to hear when a good project comes together and you learn something along the way.
Shoog
Can you pls verify /clarify what and where is “high current grounds” and “socket safety ground”.
Thank you a thousand for your help.
Apologies for such a long post
hschaser
https://www.dropbox.com/s/nc6cwbrtkr24v9g/2.jpg
https://www.dropbox.com/s/md65rmfl4imy8ko/3.jpg
https://www.dropbox.com/s/zjdsz0iz45jg54l/4.jpg
https://www.dropbox.com/s/bsz5m0w4v3tf9mv/5.jpg
This thread had really expanded both my knowledge and insight in DIY Audio.
Salute to all experts for your experiences and willingness to share.
My salute to Max who is so determined to "perfect" your preamp.
I had recently also began a tube SRPP preamp project after i got from a Chinese supplier of the attached preamp, same it is also based on the Chinese 6N3 tubes and a 6Z4 rectifier. I had custom made a transformer of 180v-0-180v, 6.3v(1A) and a 8v(1A) output as required by the board.
As the board came assembled I simply attached the transformer and i loved the sound of the pre-amp. After 2 weeks i felt there is a need to case up the board and transformer thus i began to de-solder the tube sockets, input, output and the volume pot.
I used Beldan silver plated cables for the tubes extension onto the top of chassis and Canare signal cables for both input(2x input with selector switch) and output.
I had also got a aluminium case for the transformer.
Having all holes drilled and connection made(checked). Hoping to hear (if not better) the same SQ i was blasted away with you know what! HUMS!!!!
As i began researching for answers and ways to overcome the HUM i came across you guys.(thank God).
Can you kindly advised me the following?
1. In SG we have 230V AC mains with "live" ,"Neutral" and "Earth".
What is the difference between the "earth" and "ground" ?
Mr Shoog had indicated about the “star ground” principles,
Mr. Shoog.
Glad to hear it worked out.
Now going back and paying attention to star grounding should eliminate the last of the hum you have lingering about. Its most important to not have your small signal (input RCA and grid stoppers) tied to anything high power ie your PSU caps. Tie all your small signal grounds together and then take a thin wire to your high current grounds in your power supply. Finally a big wire straight from your high current ground to your socket safety ground.
Great to hear when a good project comes together and you learn something along the way.
Shoog
Can you pls verify /clarify what and where is “high current grounds” and “socket safety ground”.
Thank you a thousand for your help.
Apologies for such a long post
hschaser
An externally hosted image should be here but it was not working when we last tested it.
https://www.dropbox.com/s/nc6cwbrtkr24v9g/2.jpg
https://www.dropbox.com/s/md65rmfl4imy8ko/3.jpg
https://www.dropbox.com/s/zjdsz0iz45jg54l/4.jpg
https://www.dropbox.com/s/bsz5m0w4v3tf9mv/5.jpg
Now I have installed the voltage divider. At center tap of filament transformer is +64V at plate voltage +245V. I think I have correct readings? I also soldered 1,2k grid stopper resistors, as I had them on hand.
I have only single 6,3V filament output on PT, should the rectifier tube have separate winding?
Hei
Nice to hear you like the now long thread
Nice board. Look like you got some quality components (compared to mine... Although those Philips caps are made 1999...
Extensions i should think is the problem actually. Have you soldered one groundcabel from - (minus) on philips cap to ground? Is volympot grounded? That caused me problem(s).
I would solder socket on back instead and have card mounted upside down with brass-spacers to get sockets to a good height.
/Johan
Nice to hear you like the now long thread
Nice board. Look like you got some quality components (compared to mine... Although those Philips caps are made 1999...
Extensions i should think is the problem actually. Have you soldered one groundcabel from - (minus) on philips cap to ground? Is volympot grounded? That caused me problem(s).
I would solder socket on back instead and have card mounted upside down with brass-spacers to get sockets to a good height.
/Johan
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