I have a Ba tube for a customer that is still getting far too much noise in via the filaments. Right now I have a LM317 as voltage reg followed by a current reg LM317...but there is still a huge amount of noise coming in through there. Diodes are Schottkey's.
Common mode filter after the regs the solution? With some 2200uF caps after the common mode filter?..
I know I'll get them silent...but was curious about how you guys solved it.
Common mode filter after the regs the solution? With some 2200uF caps after the common mode filter?..
I know I'll get them silent...but was curious about how you guys solved it.
Hi Johnny,
Here's the schematic of the psu
http://www.triodedick.com/cleo_5/cleo_voeding_gif.GIF
And here for the preamp...
http://www.triodedick.com/cleo_5/cleo_v_versterker_gif.GIF
Regards,
Bas
Here's the schematic of the psu
http://www.triodedick.com/cleo_5/cleo_voeding_gif.GIF
And here for the preamp...
http://www.triodedick.com/cleo_5/cleo_v_versterker_gif.GIF
Regards,
Bas
Assuming that you have a perfect HV supply (with very few mV ripple)
I`ll try a switching power supply desing for computer.
You can found 5V@1.5A and 12V@2A for less that $5...
I use it myself and feed a RC circuit to provide the exact voltage on my hum free #26 preamplifier.
And for the C, I use only a small 150Uf elna cerafine...
Of cource, common mode choke on the main to isolate the SPSU is a must because they might produce noise in your HV supply and get the sound worse... (I use an isolation transformer + some 0.1Uf)
give-it a try.
Regards
I`ll try a switching power supply desing for computer.
You can found 5V@1.5A and 12V@2A for less that $5...
I use it myself and feed a RC circuit to provide the exact voltage on my hum free #26 preamplifier.
And for the C, I use only a small 150Uf elna cerafine...
Of cource, common mode choke on the main to isolate the SPSU is a must because they might produce noise in your HV supply and get the sound worse... (I use an isolation transformer + some 0.1Uf)
give-it a try.
Regards
Thanks for the tip..but aren't these units huge? And only part of a complete computer psu?You can found 5V@1.5A and 12V@2A for less that $5...
Regards,
Bas
Maybe you can tried ultrasonic heating. The transformer costs $15 on Ebay. Here are some threads:
http://db.audioasylum.com/cgi/searc...sage=&sort=score&sortOrder=DESC&forum=tubediy
http://db.audioasylum.com/cgi/searc...sage=&sort=score&sortOrder=DESC&forum=tubediy
Right now I have a LM317 as voltage reg followed by a current reg LM317...but there is still a huge amount of noise coming in through there. Diodes are Schottkey's.
You don't have a filament hum problem, you have an instability in your regulators. These IC voltage regulators have internal frequency compensation, however, it only works if you connect 22uF (tantalum) -- 100uF (aluminum) across the outputs. The 100nF capacitors the schematic shows are too small. One or both are oscillating and feeding that signal into the tube via the cathode.
You don't have a filament hum problem, you have an instability in your regulators. These IC voltage regulators have internal frequency compensation, however, it only works if you connect 22uF (tantalum) -- 100uF (aluminum) across the outputs. The 100nF capacitors the schematic shows are too small. One or both are oscillating and feeding that signal into the tube via the cathode.
Quite right,
Bas you need these. They are 22uf tantalum at 35 volt.
Spares from our old airforce bases, made for Dassault .
I use them in the same pre-amp although with different valves
If you send me your postal address i'll send you some to try.
TTFN,
Retep.
Bas you need these. They are 22uf tantalum at 35 volt.
Spares from our old airforce bases, made for Dassault .
I use them in the same pre-amp although with different valves
If you send me your postal address i'll send you some to try.
TTFN,
Retep.
Attachments
Sorry to say this Bas, but I reckon you may have to use a separate filament trannie to stop interaction with the other windings.
I was using a setup with schottkies and a ronan reg (vreg -vreg-ireg) on my 1LE3 pre, and the amount of crap that came through was unbelievable. Tried everything, including rf suppression measures.
Then I put a tube shunt reg in the psu which necessitated obtaining an additional filament supply. I wired up the ronan reg to a small EI trannie and hey presto ! several orders less garbage.
pm
I was using a setup with schottkies and a ronan reg (vreg -vreg-ireg) on my 1LE3 pre, and the amount of crap that came through was unbelievable. Tried everything, including rf suppression measures.
Then I put a tube shunt reg in the psu which necessitated obtaining an additional filament supply. I wired up the ronan reg to a small EI trannie and hey presto ! several orders less garbage.
pm
I would gladly buy a bunch from you. I have those exact same tantalums in there already. I'll send you a mail.If you send me your postal address i'll send you some to try.
I think so to...but I thought I'd give it one more trybut I reckon you may have to use a separate filament trannie to stop interaction with the other windings.
I've put 22uF/35 tantalums in there already.it only works if you connect 22uF (tantalum) --

I've run a bypass capacitor from the center tap..(tried it without..as well for a while) but with it is way better.Also, you need add a bypass capacitor to one side of the filament of it.
I think I might get a seperate supply transformer for the Ba and d3a and dc the d3a supply..
I'm quite interested in that idea...but will try that in the future...for now I want to try it in a more "conventional" way.Maybe you can tried ultrasonic heating.
Thanks for all the suggestions guys! Here is a pic of the tantalums I am using..just in case you guys don't believe me
Attachments
Bas
The switching psu I use are aviable at a surplus store.
they are unboxed and measure only 2x6x1.5inch.
For more detailled picture, as mentioned on my yahoo picture account, email-me
etalon9@yahoo.ca
Regards
The switching psu I use are aviable at a surplus store.
they are unboxed and measure only 2x6x1.5inch.
For more detailled picture, as mentioned on my yahoo picture account, email-me
etalon9@yahoo.ca
Regards
Pain in A$$, but.....
I prefer a three section RC type unregulated power supply with chokes on the output. Using a hum balance pot on the filament to ground also is helpful. If using a cathode capacitor, connect that cap at the filament with a cap approximately 30% the size to the B+ supply. Thus, say a 100uF cap is from filament to ground, use a 35uF from filament to the B+.
No high frequency hash effects the sonics like from regulators and the chokes filter any other noise. The second cap from B+ to filament is well known to further reduce hum as much as 8-10dB. Ultra low DCR chokes are available from Hammond.
I prefer a three section RC type unregulated power supply with chokes on the output. Using a hum balance pot on the filament to ground also is helpful. If using a cathode capacitor, connect that cap at the filament with a cap approximately 30% the size to the B+ supply. Thus, say a 100uF cap is from filament to ground, use a 35uF from filament to the B+.
No high frequency hash effects the sonics like from regulators and the chokes filter any other noise. The second cap from B+ to filament is well known to further reduce hum as much as 8-10dB. Ultra low DCR chokes are available from Hammond.
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