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Best line stage tube?

What is the best line stage tube?

  • ECC81

    Votes: 5 9.6%

  • ECC82

    Votes: 9 17.3%

  • ECC83

    Votes: 6 11.5%

  • ECC88

    Votes: 30 57.7%

  • ECF80

    Votes: 1 1.9%

  • ECL82

    Votes: 1 1.9%
  • Total voters
    52
  • Poll closed .
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#4
M Gregg said:
Out of ecc83, ecc82, ecc88 which tube is the best for a line stage preamp
Click to expand...

Depends on what you want your line stage to do. The ECC83 is a high gain, high plate resistance, low plate current dual triode. As such, it is seldom what you want in a typical line stage: way too much gain, and way too feeble of a drive capability to handle any significant cable capacitance.

The ECC82 type is more suitable for RF applications (oscillator/buffers, frequency multipliers, intermediate drive stages) or quasi-digital applications (astable multivibrators, Schmidt triggers, monostables, RS latches). It has a bad reputation for audio useage. OTOH, it is a medium gain dual, and has the drive capability. Better to replace it with the electrically similar, though sonically superior, 6FQ7.

The ECC88 might be your best bet. It's a bit on the high side so far as gain may be concerned, but it has the drive capability, and no sonic ill-repute that I can find.
 
#5
M Gregg,

First decide the level of gain you need. You may find that you actually need no gain, in which case you may not need a line stage at all and might be able to get by with just an attenuator. Or maybe an attenuator and an impedance conversion buffer. In which case consider the Heritic buffer (from SY on this forum, use the search facility) or the Pass B1 (also on this forum, see the Pass section for ongoing threads).

If you do need gain consider the Aikido circuit, as it gives you a nice choice of tube and gain...
Download the guide here: http://tubecad.com/2009/03/13/Aikido All in One.pdf
Home site here: John Broskie's Guide to Tube Circuit Analysis & Design

: )
 
#6
Hello,
Best for what?
My preference for a line stage is a switched attenuator, a selector switch and a buffer amplifier. The buffer provides for high input impedance and low output impedance. The buffer needs to have current to drive the capacitance of the interconnects so the mousy 1 and 2 ma tubes do not have a chance. Higher Mu tubes are preferred for buffer (gain ~= 1). Check this out for a line stage. Aikido Cathode Follower & More Triadtron
I have been enjoying it for the last couple of months. Talk about Slam. Solid and clean sound without all the not needed gain.
DT
All Just for fun!
 
#8
Hi,

DualTriode said:
Hello,
Best for what?
My preference for a line stage is a switched attenuator, a selector switch and a buffer amplifier. The buffer provides for high input impedance and low output impedance. The buffer needs to have current to drive the capacitance of the interconnects so the mousy 1 and 2 ma tubes do not have a chance. Higher Mu tubes are preferred for buffer (gain ~= 1). Check this out for a line stage. Aikido Cathode Follower & More Triadtron
I have been enjoying it for the last couple of months. Talk about Slam. Solid and clean sound without all the not needed gain.
DT
All Just for fun!
Click to expand...


What about the impact on the sound of the cathode decoupling caps?
Besides that, this circuit aslo requires DC blocking caps at the input....

IMHO, a WCF combined with a well designed (regulated) PS may well trump this circuit if you do not need any gain.

OTOH, you may want to try to remove the decoupling caps, maybe adjust the value of the cathode resistors to correct grid bias and end up with a still better sounding stage just the same...?

Cheers, 😉
 
#9
Hello,
The Aikido Cathode Follower I have operating in the chain does not have the optional cathode bypass capacitors installed. Check the previous TubeCad Blog Low output impedance Aikidio and the Aikido Cathode Follower there were no bypass capacitors shown at this earlier discussion of the ACF.
The main reason I prefer today the ACF to the WCF is the power supply noise and distortion canceling that happens at the lower triode.
There is no ultimate or best, this is for fun. A good friend of mine married for 20 years says that next time he might try a tall redhead.
DT
All Just for fun!
 
#14
Allen Wright said:
I suggest you build the line stage section of my FVP-5A, available under schematics in my website:

Vacuum State - High End Hifi Equipment

Uses 6DJ8/6922 tubes, can be massaged to suit your system, and the kinda complex output section is by far the best sounding tube output topology I have found in 40 years of researching.

Regards, Allen
Click to expand...

From what's written on the schematic I understand that tubes like 6H30pi will have a benefit. Will that be a benefit in sound quality?
Also it says that with different tubes one will have to play with the 2K2 cathode resistors. Does that apply to both 2K2 cathode resistors?
 
#15
Joshua_G said:
From what's written on the schematic I understand that tubes like 6H30pi will have a benefit. Will that be a benefit in sound quality?<<

Yes, mostly because the 6H30 can run a lot more current, and IME more current always sounds better - especially in the output section.

>>Also it says that with different tubes one will have to play with the 2K2 cathode resistors. Does that apply to both 2K2 cathode resistors?
Click to expand...

The first 2k2 sets the stage gain, and also the operating point of the first tube.

The second 2k2 sets the running current of the output totem pole.

As described, the gain may be too high for some situations - the only way we have found to lower it with adding any (YUK) NFB, is to run something like a 25k R from the first anode to gnd. Then change the 1st cathode R to get the anode V back to where it should be (circa half the B+ rail).

By varying these two Rs, you can have whatever gain you want easily with little/no sonic penalty.

If you want to know how this schematic sounds, the SVP-2 that's reviewed on my site uses almost exactly the same circuit:

http://www.vacuumstate.com/fileupload/vacuum_state_low_res.pdf

Regards, Allen
 
#16
Thanks, Allen.
I read that review before (along with other reviews of some of you products) and I believe I have a good clue about how they sound.
Will replacing the line stage tubes with 6H30pi tubes have a benefit on the sound quality?
Also, what's the recommended current to operate 6H30pi tubes on the gain stage and on the emitter follower?
 
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