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27> EL34 (triode) > 300B

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nomiconxp

nomiconxp

Member
Joined 2009
#1
I have some tubes laying around and i am thinking of trying out this concept.

27 150V 5 mA
EL34 triode strap 250V 10k load 30mA
300B 425V 3.5k 70mA fixed


I haven't sit down on calculations and grafs just thinking.
I'm open to any suggestions. What do you think
 
#3
I built an amp like that using a 76 with CCS load RC coupled to the triode connected Mullard EL34 RC coupled to the AVVT 300B. The output transformer was a Tango 5002. I was very dissapointed in this amp and found that a 3 stage amp using a 76 RC to 5687 RC to 300B better; 76 RC to 5687 DC to 300B even better and E180F triode direct coupled to the 300B the best by far.
 
#4
nomiconxp said:
I'm open to any suggestions. What do you think
Click to expand...

If you want to use the EL34 as a driver then use a good interstage transformer. RC coupling is pointless as a 10K anode resistor will require 550V supply (even more if using self bias) and a rather big resistor to cope with the power dissipation. With a good Interstage it also will sound a lot better, IMHO.
 
#6
I agree 100%
Also EL34 offer a great sound as SE 6 to 8 W output.
Click to expand...
For a 300B driver a EL34 is a little bit overshoot😀
A EL34 with Interstage-transfo. can easy drive a GU70 or a 845.
But it sounds so good with a 300B.
Imho its the best driver-stage i ever build.

Hilmar


P.S.: I like your signature - its the best one can do - thank you.
 
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#7
Palustris said:
...E180F triode direct coupled to the 300B the best by far.
Click to expand...

In your opinion, a single E810F-triode is up to driving a 300B? If so, then it should make a super driver for 2A3 too. Also, an LTP made from two E810F-triode should drive PP 2A3, correct?

If the consensus is that this is a good sounding combination of tubes, I think I'd like to try a 6J9P-triode LTP DC-coupled to PP 2A3's. Just a two-stage amp.

Sorry for the off-topic remarks...

--
 
#10
rongon said:
In your opinion, a single E810F-triode is up to driving a 300B? If so, then it should make a super driver for 2A3 too. Also, an LTP made from two E810F-triode should drive PP 2A3, correct?
--
Click to expand...

Yes, the E180F is marginal for driving the 300B, particularly with no preamp stage, but is perfect for the 2A3. I bias mine at 1.4V using a couple of diodes with 145V on the plate for 10mA with a choke load. The measured gain of the triode connected E180F is 46 so the input sensitivity is just over 1V input for a two stage amp with no preamp. The E180F replaced a 6N23P-EV for a very good improvement in sound.

I have a PP 6V6 amp on the drawing board using two E180F in a LTP with a CCS on the cathodes. The first grid is driven by the input signal and the second grid accepts feedback, just like the 'El Cheapo'.
 
#11
Thanks Hilmar53 i finally settled on the 46 for the driver and with a interstage transformer i want to make this amp DHT! 🙂 except the input i'm thinking about the D3A CCS loaded. Will show schematic soon enough.

EL34 is a great tube i'm hearing music to one right now in my lab with a 6n1p driving it.
I haven't used a E180F ever before isn't that close enough to the D3A?
 
#13
Hilmar53 said:
I have never done something with the 6c33 but i´m sure the EL34 will do the Job.
Look at the webside of the great Sakuma San.( He is one of my Gurus )
March 1994
It´s a PP but 845 drives 6c33c!!!!
Perhaps some day i will build this crazy beast - just for fun🙂

Hilmar
Click to expand...
Hi,
Iam in process or ordering a 6C33 SET.
My builder says the 6SL7 is the best sound tube to drive a 6C33, but I have a dozen of 6N1P-EB and none 6SL7 or its versions (but I would buy 6H9C).

How is the 6N1P sound as driver of a 6C33??
The 6SL7 are this good??
Thanks for help
 
#14
Hi FullRangeMan !

I have tried in my 6c33c SE ( based on simplex ) several 9 pin tubes to drive 6c33c with small adjustments:

6n1p ( bit too "short" in my circuit) but sounds nice too.
6n6p, 6n6p-i and Chinese 6n6-T. i like the sound of 6n6-t over others 6n6.the second in range - 6n6p-i (but draws more current for heaters);
6cg7/6fq7 - sounds very good;
6gu7 - also good ones and cheap.

i have small hum with some 6n6p and 6n6p-i tubes - lets say from eight tubes - two have some 100hz hum. by the time it decreases for some tubes to inaudible level.

This is my subjective observations but maybe can be useful to you.
 
#15
osscar said:
Hi FullRangeMan !

I have tried in my 6c33c SE ( based on simplex ) several 9 pin tubes to drive 6c33c with small adjustments:

6n1p ( bit too "short" in my circuit) but sounds nice too.
6n6p, 6n6p-i and Chinese 6n6-T. i like the sound of 6n6-t over others 6n6.the second in range - 6n6p-i (but draws more current for heaters);
6cg7/6fq7 - sounds very good;
6gu7 - also good ones and cheap.

i have small hum with some 6n6p and 6n6p-i tubes - lets say from eight tubes - two have some 100hz hum. by the time it decreases for some tubes to inaudible level.

This is my subjective observations but maybe can be useful to you.
Click to expand...
Thanks Osscar, it help indeed.

The 6H9C Reflector is a military tube??
It also good as the 6SL7??

My original plan was to use 6N1P(gain 33x) or 6N2P(gain 100x) for higher gain, I would like keep all tubes Soviet, but he are flat 6SL7 are the best tube for 6C33.
So this get me by surprise.
 
#16
The 6H9C Reflector is a military tube??
It also good as the 6SL7??
Click to expand...

Acording to "Electronic Universal Vade-Mecum" the 6H9C is the russian equivalent to 6SL7. Why not build the amp with it and later you can change to 6SL7 if you like or to that tube wich sounds better for you.
Imho the high quality 6H9C from the soviet-time is better than a 6SL7 of dubios new production.

Hilmar
 
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