Thaks for all the input on the #30 line stage but think I should open another thread for these since we don't want to highjack this thread started by Klaus🙂 on another matter.
Re: ECC88
I would rectify it with a 5AR4/5AS4 or similar. the meagre current draw of the circuit doesn't justify the heaters on a pair of damper diodes.
B+ v1 (no AC on chassis): Next have a pi-filter with the first cap in the remote supply. 100uF is tons here. then in the preamp chassis proper, the biggest L value choke you can, with say another 100uF. Then I would add a CCS and active shunt reg, but a glow diode would do in place of the active stage.
B+ v2: As above, but have an LC on amp chassis with PP cap.
Filaments v1 (no AC on chassis): Schottky rectified, first cap in remote PSU. In preamp, a CM choke ($2), big cap, 3 terminal series reg, CM choke, current source from another 3 term reg, with a TL431 shunting any excess. Float the lot at +40V above ground.
Filaments v2 (my choice): 7-8Vct transformer or a 6.3V if specced for a couple of amps, CM choke-> small poly cap with good HF performance (or a ceramic) -> CM choke, another small cap right at the socket across the filament pins. Float the lot through the transformer CT at +40V.
All PSU caps, except the second C in the B+ are good quality electrolytics. The second C should be a quality PP or PP in oil. CM chokes are the biggest catalogue values you can get cheap that exceed 500mA.
There isn't any need for DC filaments in this circuit if it's only handling line level signals, nor is there any need to keep AC off the main chassis if good construction techniques are used.
Frank,fdegrove said:
I would rectify it with a 5AR4/5AS4 or similar. the meagre current draw of the circuit doesn't justify the heaters on a pair of damper diodes.
B+ v1 (no AC on chassis): Next have a pi-filter with the first cap in the remote supply. 100uF is tons here. then in the preamp chassis proper, the biggest L value choke you can, with say another 100uF. Then I would add a CCS and active shunt reg, but a glow diode would do in place of the active stage.
B+ v2: As above, but have an LC on amp chassis with PP cap.
Filaments v1 (no AC on chassis): Schottky rectified, first cap in remote PSU. In preamp, a CM choke ($2), big cap, 3 terminal series reg, CM choke, current source from another 3 term reg, with a TL431 shunting any excess. Float the lot at +40V above ground.
Filaments v2 (my choice): 7-8Vct transformer or a 6.3V if specced for a couple of amps, CM choke-> small poly cap with good HF performance (or a ceramic) -> CM choke, another small cap right at the socket across the filament pins. Float the lot through the transformer CT at +40V.
All PSU caps, except the second C in the B+ are good quality electrolytics. The second C should be a quality PP or PP in oil. CM chokes are the biggest catalogue values you can get cheap that exceed 500mA.
There isn't any need for DC filaments in this circuit if it's only handling line level signals, nor is there any need to keep AC off the main chassis if good construction techniques are used.
Off the top of my head suggestion based on the list I had in front of me (ie whats in my tube box). Haven't used one of these in years and my recollection was around 100mA current through them. I didn't go looking for a lot of alternatives, and you're right, it is waaay overkill, but I'm using mine (5AR4) in my bass guitar preamp where it's gotta power 3 12AX7s..... Cost me all of $1 NOS. Think I'll have any reliability problems with it?Colt45 said:
6X4 would be a little closer to actual circuit requirements.
oh, i see 🙂
it would work fine, just overkill. 15w is a fair chunk of heater power.
i like the 6X5/6X4 for small jobs because:
cathoded, so you dont need a seperate filament supply
only 600ma filament draw (hence you dont need a mammoth trafo for your preamp)
good for around 70ma or so
6X4 is a mini, 6X5 is identical but the predesecor (spelling), so its octal. (T9 I think, like a 6V6).
I really need to get working on something.. im not sure what though.
(not enough iron right now 🙁 )
I got a 6N5P in the mail the other day.. seems really neat, and pretty high quality (4 mica spacers!)
Well, I'll think of something.
it would work fine, just overkill. 15w is a fair chunk of heater power.
i like the 6X5/6X4 for small jobs because:
cathoded, so you dont need a seperate filament supply
only 600ma filament draw (hence you dont need a mammoth trafo for your preamp)
good for around 70ma or so
6X4 is a mini, 6X5 is identical but the predesecor (spelling), so its octal. (T9 I think, like a 6V6).
I really need to get working on something.. im not sure what though.
(not enough iron right now 🙁 )
I got a 6N5P in the mail the other day.. seems really neat, and pretty high quality (4 mica spacers!)
Well, I'll think of something.
CHOKES
Hi Tony,
Have you tried a choke of say 10-100H iso of the aircore?
All,
Leaving rectification open for debate,any of you in favour of tube regulation and anode choke iso CCS+Sand reg?
I've got a tube reg circuit using an ECL85/6GV8 and a 85A2/5651
that can be adjusted to make B+ from 250V to 150V.
It is simple to build and by its' very nature provides a slow B+ ramp up for the valves.
One per channel would make it ideal in this case.
Together with the anode choke it would provide for a more neutral sound than the CCS IME.
Naturally the tube reg can be used with a CCS too.
Let the voting begin, 😉
Hi Tony,
Have you tried a choke of say 10-100H iso of the aircore?
All,
Leaving rectification open for debate,any of you in favour of tube regulation and anode choke iso CCS+Sand reg?
I've got a tube reg circuit using an ECL85/6GV8 and a 85A2/5651
that can be adjusted to make B+ from 250V to 150V.
It is simple to build and by its' very nature provides a slow B+ ramp up for the valves.
One per channel would make it ideal in this case.
Together with the anode choke it would provide for a more neutral sound than the CCS IME.
Naturally the tube reg can be used with a CCS too.
Let the voting begin, 😉
Re: CHOKES
Mmmm, 100H, sounds like a ray beam to the plate. Do you want plate fumes inside your tube? should be a geat show on parties.
Just kidding.
I haven't tested a cored coil on that position but maybe I should. At this moment don't have this iron, but will try one coil of a transformer and see what happens. The current is so low that may not need a gaped iron.
fdegrove said:
Mmmm, 100H, sounds like a ray beam to the plate. Do you want plate fumes inside your tube? should be a geat show on parties.
Just kidding.
I haven't tested a cored coil on that position but maybe I should. At this moment don't have this iron, but will try one coil of a transformer and see what happens. The current is so low that may not need a gaped iron.
GRANTED...
Hi,
Granted I exaggerated the values.
A trick I learned from our marketing man Per-Anders.😀
Why not give it a try?
Reasonable values of choke,I mean.
It really is an ear-opener.
Ciao,😉
Hi,
Granted I exaggerated the values.
A trick I learned from our marketing man Per-Anders.😀
Why not give it a try?
Reasonable values of choke,I mean.
It really is an ear-opener.
Ciao,😉
I've also tried a very similar hybrid circuit . Must have been around twenty years ago 🙂 Tried it as a MC step-up, as stages in RIAA and as a line level. You may like it but certainly not me. The SS CCS are intolerable and the poor ECC88, not a briliant sounding valve at best, runs completely out of steam at line levels and 30 odd volts at anode. It's easy to build as a first project but with the potential to put someone off valves for life.
Ooops. Just noticed that's not a CCS. Even worse.
cheers
peter
Ooops. Just noticed that's not a CCS. Even worse.
cheers
peter
I want to go one step further and add an SS-CCS instead of the plate resistor. I read many good things about that topology, and although I must admit that I do not have own experience, I "have this feeling"...
Here is the input part of the "Zodiac" amplifier (by Morgan Lundberg) with a CCS "heavily" inspired by bottlehead, I think. Will it work also for "my" E88CC single stage ? How do I calculate the current ?
Here is the input part of the "Zodiac" amplifier (by Morgan Lundberg) with a CCS "heavily" inspired by bottlehead, I think. Will it work also for "my" E88CC single stage ? How do I calculate the current ?
Attachments
CCS and Transformer coupled 6DJ8
Klaus,
I have tryed CCS with a MOS FET with single and parallel 6DJ8 but didn't like it's sound, but as usual this is a matter of preference. Im my case it was compleatlly veiled, lack of transients and very laid back plus poor bass and mid bass, well not natural in my opinion.
If you want to try something diferent for plate loading I'd go for a transformer loading, using one coil for loading and the secondary for output, this is a very atractive line stage to test in my view provided you have a good tranny.
Though a 6DJ8 would not be the tube of preference, in this case I would use a 417A which has a mu of 43 and transconductance of 24,000 umhos and also a low RP. This tube will run on 160V and 20 mA.
There is a very good article on this subject (actually two articles) on page 16 of Sound Practices issue #10 which I have on my hands describing this line stage and giving the supplier information for the transformer (Italy) maybe you can find something on the web under the names of the authors Ciro Marzio, Cristiano Jelasi and Luca Chiomenti.
The second article on the same mag is Diego Nardi from Audio Note Italia
Klaus,
I have tryed CCS with a MOS FET with single and parallel 6DJ8 but didn't like it's sound, but as usual this is a matter of preference. Im my case it was compleatlly veiled, lack of transients and very laid back plus poor bass and mid bass, well not natural in my opinion.
If you want to try something diferent for plate loading I'd go for a transformer loading, using one coil for loading and the secondary for output, this is a very atractive line stage to test in my view provided you have a good tranny.
Though a 6DJ8 would not be the tube of preference, in this case I would use a 417A which has a mu of 43 and transconductance of 24,000 umhos and also a low RP. This tube will run on 160V and 20 mA.
There is a very good article on this subject (actually two articles) on page 16 of Sound Practices issue #10 which I have on my hands describing this line stage and giving the supplier information for the transformer (Italy) maybe you can find something on the web under the names of the authors Ciro Marzio, Cristiano Jelasi and Luca Chiomenti.
The second article on the same mag is Diego Nardi from Audio Note Italia
ECC88/6DJ8
Hi,
A lot of the expected sound can be read from the curves...however...while I agree there are better tubes, the ccs when well implemented can take that tube to another level.
So...How do you implement it correctly?
If you have simulation software or not doesn't really matter,just do the calcs as if the tube were resistively loaded on the anode.
Calculate the current going through the anode resistor.
You now know the current sunk by the tube and can go looking for an appropriate semi-conductor having the required Idss.
Do regulate the voltage preceding it by using a tubed or SS shunt regulator.
The CCS will have an impact on the sound (semi hybrid) and will raise its' amplification factor close to ideally obtainable.
What a lot of people don't realise is that by doing so the tube acts in a far more linear manner...
Other topic perhaps?
An atypical result surely?
Cheers,😉
Hi,
A lot of the expected sound can be read from the curves...however...while I agree there are better tubes, the ccs when well implemented can take that tube to another level.
So...How do you implement it correctly?
If you have simulation software or not doesn't really matter,just do the calcs as if the tube were resistively loaded on the anode.
Calculate the current going through the anode resistor.
You now know the current sunk by the tube and can go looking for an appropriate semi-conductor having the required Idss.
Do regulate the voltage preceding it by using a tubed or SS shunt regulator.
The CCS will have an impact on the sound (semi hybrid) and will raise its' amplification factor close to ideally obtainable.
What a lot of people don't realise is that by doing so the tube acts in a far more linear manner...
Other topic perhaps?
An atypical result surely?
Cheers,😉
Re: CCS ECC88/6DJ8
Could you give us a proposal Frank? Please?
I'm not much into calculating these stuff.
fdegrove said:
Could you give us a proposal Frank? Please?
I'm not much into calculating these stuff.
Euridice
Klaus,
The preamp name is Euridice, you can find a sample by Thorsten Loech with 5842/417A at:
www.fortunecity.com/rivendell/xentar/1179/projects/euridice/euridice.html
The transformer are Bartolucci at around US$100 each.
Apparently there have been some people making this line stage with a 6DJ8 but haven't read any comments yet.
About 6 years ago I purchased 2 RCA 417A's to try this setup but never came to order the tranies. To bad I guess.
Klaus,
The preamp name is Euridice, you can find a sample by Thorsten Loech with 5842/417A at:
www.fortunecity.com/rivendell/xentar/1179/projects/euridice/euridice.html
The transformer are Bartolucci at around US$100 each.
Apparently there have been some people making this line stage with a 6DJ8 but haven't read any comments yet.
About 6 years ago I purchased 2 RCA 417A's to try this setup but never came to order the tranies. To bad I guess.
Re: Euridice
So subbing a 6DJ8 into the Euridice will work, sort of. Basically a complete redesign that will end up being <i>reminiscent</i> of the Euridice.
Cheers
I don't think the 6dj8's will have enough gain, to exceed the loss in level due to the transformer step down. The 6DJ8 also has an Rp about 3-4 times the 417A/5842 so will require different transformers.apassgear said:
So subbing a 6DJ8 into the Euridice will work, sort of. Basically a complete redesign that will end up being <i>reminiscent</i> of the Euridice.
Cheers
Not specifically the Euridice, but similar circuits.apassgear said:
What sort of comment do you want?
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