| Kashmire |
I'm ordering a couple of 6c45pi.
What's the going controversy over these tubes? According to spec, these things are miracle tubes! High gain and low plate resistance triode.
With 150V and 35mA (7 watts on the plate), not a bad deal....
If you've heard or built using a 6c45pi, please post your comments. |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Kashmire
What's the going controversy over these tubes?
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Not sure what the "going controversy" is. Like with any Valve, the 6S454 needs to employed intelligently to sound good. It has two peculiarities, one a very large sample to sample variation making pair matching mandatory and secondly a tendency to oscillate (like any High Gm Valve), which requires some care in implementation.
Sayonara |
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| Kashmire |
I’ve heard two reports about some of the Russian “super tubes” like the 6C45pi. The detractors say it sounds like solid-state; really dry. The admirers say the incredible performance and versatility makes it a great candidate for new designs.
Both may be true. It may be a high-performance tube that sounds like solid-state.
I intend to listen to a 6C45pi – but it requires laying out a whole new circuit, when I’ve already got a lot going on. I wanted opinions from people who have already tried it. |
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| fdegrove |
Hi,
O.K...My New Year gift to you:
| quote: | | The admirers say the incredible performance and versatility makes it a great candidate for new designs. |
The latter party is right and as Thorsten said, it needs some precautions to use.
Mostly gridstopper all over the place and careful selection.
Other than that it's a godsend..............
Get a dozen,;)
P.S. There are some other ex-USSR tubes you'd care to learn about....
Cheers,;) |
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| Kashmire |
I admit, I'm a bit of a noobie.
At building with tubes, that is. I've spent a decade of doing calculations, working equations, plotting load lines, and drawing schematics, but never built anything.
I'm a changed man. I've been building like a lunitic for a couple months, changing my ways and redeeming my past. All those schematics that I've drawn for the last couple years are becoming real hardware.
My latest batch includes tubes suitable to drive the Lundahl LL1660s/18mA interstage transformer. Darn! Why didn't I get a higher current interstage to try the 6c45pi?
My latest efforts use the 7788/E810F or 5965 to drive the interstage. In turn, the interstage drives Tung-sol 6550 or JJ KT-88 grids. I'm an aspiring roller, so I can't wait for my EL34s.
Now that you know this, what's the rest of the russian super-tubes out there? |
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| fdegrove |
Hi,
| quote: | | Now that you know this, what's the rest of the russian super-tubes out there? |
There are a couple but here are the ones that amaze the world:
6C19P, close to the TFK ED 8000.
6C41P, close to halve the famous Mig tube 6C33C.
6H1P, some 6DJ8 but far from equivalent.
6H30P, BAT's favourite....
There's more, much, much more....keep'em alive by buying them.
BTW, I hear Svetlana is in big trouble since their last adventure into the U.S...
Nobody wants them to fade into history....
Cheers ;) |
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| woody |
The One tube design page feactures a few circuites using this
tube.
http://digilander.libero.it/paeng/one_tube_design_page_CIRCUITES.htm?
Woody |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Kashmire
My latest batch includes tubes suitable to drive the Lundahl LL1660s/18mA interstage transformer. Darn! Why didn't I get a higher current interstage to try the 6c45pi? |
Using the 6S45 at 18mA is fine, trust me. I prefer even lower anode currents, make the anode current too high and the sound of ANY High Gm Valve I have played with becomes hard and steely, pretty much that kind of sound people have criticised in the 6S45 when used as driver valve, simply because they acted on the idea "if it's rated at 50mA Max I must operated it at 60mA!".
| quote: | Originally posted by Kashmire
My latest efforts use the 7788/E810F or 5965 to drive the interstage. |
Triode Wired E810F sounds better than 6S45 but is harder to find and not in current production. BTW, the E180F is in current production and makes a good "pseudo 417A".
| quote: | Originally posted by Kashmire
Now that you know this, what's the rest of the russian super-tubes out there? |
Given the ridiculous rises in price since the "well known" super valves such as 6N6, 6N30 and 6S45 became known in the west you must forgive the cognescenti for not divulging the Numbers of the real sleepers still languishing in Stores from the cold war in Russia. We used to buy the 6S45 for around 6 Bucks each, landed cost (inclusive shipping, taxes and duties!) before they became fashionable.
Sayonara |
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| Silver Stealth |
Hi Guys
I was running three NOS RCA Blackplate 5963s in parallel (six triodes) per channel in a plate loaded triode config before ripping it all out and trying the 6C45pi. Despite having very nice components (remote PSU with dual mono transformers, Shallcos, BGate caps, corian box, etc) the bass was a bit shy and it lacked dynamics compared to my EAD processor...it was also pretty microphonic.
I've now got two of the 6Cs in there alone, and I am very impressed with the results. 170V plate voltage (higher than spec but told this is OK, check the size of the plates out!), 40mA current (must try lower currents later based on the last reply, thanks!), 47R cathode with 220uf bypass. I used 100R AND ferrite on lead to grid and interconnected grids with a ferrite on the lead also. No oscillation problems at all. Bass is heaps better, dynamics are incredible and there is more gain than I know what to do with. The non microphonic nature of the tubes is also excellent.
I have been trying different heater voltages also, and seem to prefer higher than 6.3V than lower. YMMV. This counteracts the slight brightness that is mentioned earlier in this post. It seems more fleshed out at say 6.5V I believe.
Well worth trying guys, IMHO and cheap too
Cheers, Kendrick |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Silver Stealth
it was also pretty microphonic.
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This suggest you had oscillation. The 6S45 is about as dead sonically when pinged as it gets. If it's microphonic, you have oscillation, trust me.
Sayonara |
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| Silver Stealth |
Thanks for the tip, just wish I had a CRO to verify.... ;) Fortunately I do have access to one occasionally so I'll investigate further.
Interestingly enough, when I tried the 82R/68uf cathode R/C combo the plate voltage went up which I thought was unexpected (from 47R/220uf). Can someone explain this? I was hoping to simulate in TubeCAD but the tube isn't in the database and I don't seem able to add the 6c to it either.
Also this new R\C combo did lead to oscillation in the right channel. Major bummer :hot:
I have seen about a 10V difference in plate voltage between the channels which I assume comes back to the unmatched tubes.
Cheers, Kendrick |
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| EC8010 |
| 6C45pi is a cracking little valve with super linearity, but it needs care to stop it oscillating at VHF. Decouple the HT locally, use a carbon-film grid-stopper, and if you use it as a cathode follower, add a cathode-stopper. It needs a bit of current to wake it up, but 15mA is quite sufficient. I don't believe the 7.8W rating from that envelope at normal temperatures, although a gentle draught of air at -50C (temperature at 50,000 feet) would comfortably enable the rating. |
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| Silver Stealth |
Hi and thanks for the tips EC8010...
I decoupled the HT (1000pf/1000V ceramic) and also removed the inter grid wire with ferrite I added earlier. I then added a ferrite on the cathode lead as well, and it seems to have cured the oscillations using the 82R/68uf cathode R/C combo (at least for the last five minutes I've been listening to it!) :bigeyes: |
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| mcs |
| quote: | Originally posted by Kuei Yang Wang
BTW, the E180F is in current production and makes a good "pseudo 417A". |
Still in current production? Who, where, why?
I bought some of them when they were on sale at AES, but I haven't done anything with them yet. I have used the 417As in a tape head preamp though...
Best regards,
Mikkel C. Simonsen |
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| fdegrove |
Hi,
| quote: | | I decoupled the HT (1000pf/1000V ceramic) and also removed the inter grid wire with ferrite I added earlier. I then added a ferrite on the cathode lead as well, and it seems to have cured the oscillations using the 82R/68uf cathode R/C combo (at least for the last five minutes I've been listening to it!) |
And no idea about the bandwidth of this circuit, I reckon?
Cheers,;) |
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| EC8010 |
| Glad to hear it's working. Does it sound any better? |
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| Silver Stealth |
Early days yet to say how it sounds, but when it was oscillating it seemed to have lower output in the channel that I believe was oscillating. Now they seemed better matched which is obviously a good thing. Dave Weckl live sounds pretty good...
fdegrove, your brief feedback is appreciated but why not share your knowledge with the team please...forgive me, I'm trying to learn here.
The ferrites chosen were the Nickel/Zinc type catalog no 232-9628 in RS Components, page 922 of the Aussie catalog - these have a 49dB attenuation at 10Mhz, 72 at 25Mhz and 101dB at 100Mhz...if you are implying that this limits the bandwidth are you suggesting these will attenuate in the audible frequency range if used on the cathode or grid leads? Without a curve of their attenuation in the kHz range or a cro handy it's hard to verify...
Keep the good ideas flowing guys... |
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| Silver Stealth |
Sound comments as-is
Nitin Sawhney - Migration - Tk 1 - excellent depth. Voice is very airy and natural sounding. Bass may be a touch plummy, but has wonderful texture (and is synthesized so hard to know what it is meant to sound like). No oscillation and nicely centred image. Tabla is nicely palpable - there's a lot to like... |
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| fdegrove |
Hi,
| quote: | | fdegrove, your brief feedback is appreciated but why not share your knowledge with the team please...forgive me, I'm trying to learn here. |
What team?
Or do you expect me to teach the world how to chemically merge Au atoms to Ags...??
Please...?
Cheers,;) |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by mcs
Still in current production?
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So it seems. If not Russia has huge cold war stocks of them.
| quote: | Originally posted by mcs
Who?
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Either Reflektor or Saratov.
| quote: | Originally posted by mcs
where?
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Russia.
| quote: | Originally posted by mcs
why?
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Good valve?
Simply wire as triode. Drops in for 417A with (of course) different pinout and slightly higher Mu and Ra.
Sayonara |
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| Kashmire |
| quote: | Originally posted by Silver Stealth
fdegrove, your brief feedback is appreciated but why not share your knowledge with the team please...forgive me, I'm trying to learn here. |
Geeesh! Why must we all feel guilty for trying to learn? What's wrong with this picture? Learning is what DIY is all about.
You shouldn't be asking for forgiveness for trying to learn. |
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| Brian Clark |
I have been using a pair of 6S45P-Es as power valves (don't laugh, my speaks are >100dB/1W, are yours?) quite satisfactorily for more than a year.
The design can be found here
www.sempermusica.com
I found that ferrite beads at the grid pins were not enough to kill oscillations (whereas they were sufficient for 3A/167Ms). I ended up with 100 ohm carbon composition hard up against one grid pin valve base tag and the other grid tag clipped flush to the base. No stoppers on unused cathodes nor any prophylactics on the heaters. 200MHz Tek scope shows a clean trace and the sonics are fine. However the sound is a little on the transistory side and when Peter Millett tested one of these valves at my operating point (195V @ 45mA) he found a little too much 3rd and 5th harmonic in the spectrum. As KYW has observed, these hot little Russkie babes should really be run on less juice - 10-15mA - when the 3rd & 5th disappear into the noise floor.
Brian. |
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| Silver Stealth |
So Brian, and KYW can you describe your preferred operating point in totality for this tube? Sounds like I am still running too much current (about 26mA at present).
Brian, when you say grid tag clipped flush to the base, do you mean the unused grid tag soldered to the centre pin (which is o/cct) of the tube base?
Oh for a 200Mhz cro...maybe I can borrow one from work over the weekend...
And how well filtered are your PSUs? Using CRC, CLC, or other? At present I have CRCC with the first and second Cs at 220uf, R is 665R and third C is 200uf mounted in the main chassis - the CRC are in a seperate box with the mains transformers). A high DCR choke might be the ticket - anyone care to recommend inductance value that won't constrain the dynamics?
Cheers, Kendrick |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Silver Stealth
So Brian, and KYW can you describe your preferred operating point in totality for this tube? Sounds like I am still running too much current (about 26mA at present).
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I started with the 6S45 @ 150V/30mA and worked my way down step by step to 12mA. Later I switched to WE 437A and there I found that going further down to around 6mA like seen in some Japanese schematics from MJ improved things further.
All this was as Driver for a 300B, CL coupling to 300B, R or Choke load on 6S45/437A.
| quote: | Originally posted by Silver Stealth
And how well filtered are your PSUs? Using CRC, CLC, or other?
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The 300B PSU was CLCLC with a "tuned" first Inductor to maximise 100Hz rejection and then RC to 6S45/437A, all PSU Cap's Film types 47uF except first which was 1uF Foil & Film, 5R4/5U4/274A rectifiers.
Sayonara |
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| fdegrove |
Hi,
| quote: | | Brian, when you say grid tag clipped flush to the base, do you mean the unused grid tag soldered to the centre pin (which is o/cct) of the tube base? |
From reading his website, I think he meant it literally...
It does away with the stub aerial to some extend at that end.
No idea on how effective it really is...
Cheers,;) |
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| Brian Clark |
Hi Kendrick and fdgrove
I just snipped the valve holder tag corresponding to the unused grid pin flush to the base of the holder and, with the gridstopper on the other grid tag, my amp behaves beautifully. Other environments may make further precautions necessary but I have had no problems reported from others who have built Spuddo.
The PSU is LCLC with 47uF and 200uF (parallel sections of Cerafine 100 + 100). The input choke is a low DCR Lundahl and the second a 150 ohm DCR cheapie from Maplin. The amp is built exactly as per the diagram on my webpage. The mains is shunt filtered using KYW's TNT design.
And that's it.
Very effective for me.
The "best" distortion spectrum from Peter Millet was 10mA @ 150V AFAIR and I believe the results can still be found at
http://pmillett.addr.com/pentodes.htm
Brian. |
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| woody |
I just built the 6c45pi amp found at http://digilander.libero.it/paeng/pae.htm
I am realy impressed with how this little amp sounds
and the Black Gate cathode bypass haven't even had
a chance to breakin.
Woody:) |
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| ReinoutdV |
Hi,
with the 6C45 i built a phono amp. The tube is simply "invented" for that purpose.....
As stated in other replies: low on voltage and milliamps. And i also had to use gridstopper (used a tantalum 150 ohm).
The amp is built on 2 chassis. One for audio and the other is the powersupply. Picture included.
Schematic in words:
6C45 - RIAA - 6C45 - interstage - 6SN7 - output transformer.
Why: because there is only one tube manufacturer of these tubes. So: take it or leave it. With a 6SN7-stage after the phono-amp itself i can finetune the tonal quality with the abundance of all available 6SN7's. At this moment i'm using KenRad's for the 6C45 does sound a little cool and the KenRad's just bring the total sound back in balance.
Powersupply: massive. But now the amp is extremely quit and stable.
Reinout |
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