ECC82 in V3 Position of DSL40C???

Jethro Rocker said:
So you did change out V4? I went extreme once amd put an AU7 in there and the volume dropped way off so I coild turn it up higher or just to adjust for the eealky touchy JCM800 volume control.

I found little difference as well with a 5751 simoly because gain factor is not too different. I did try an AU7 or AY, I can't recall, in the 6505 but it killed too much gain.
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You are right. That's exactly how it behaved, but on "Lead 2" the DSL40C has so much gain to spare that it works out great!!!!!
 
@Amp Mad Scientist or @ivan H or anybody else...can you address the higher transconductance of the 12AT7 compared to the 12AX7???

I have read that the 12AT7 has almost 10 times the current available to drive the output tubes before the phase inverter starts to break down and a transconductance of 5500 vs 1600 of the 12AX7.

Does this hit the power tubes harder???
 
Without getting technical (which I've had far too much to drink for at the moment), no, I wouldn't expect it to hit the power tubes harder. 12AX7, 12AT7, 12AY7 or 5751 are all good candidates for the PI position, but it is the 12AX7 that will drive the power tubes hardest in a guitar amp, even when the supporting circuitry is optimised for the 12AT7 (lower value plate resistors & larger value tail resistor). Think of the amps that Leo changed over from a 12AX7 to 12AT7 phase inverter (pro, showman, tremolux etc, etc), the 12AT7 PI amps exhibit more clean headroom from the power amp than their earlier 12AX7 PI counterparts. Cheers
 
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ivan H said:
Without getting technical (which I've had far too much to drink for at the moment), no, I wouldn't expect it to hit the power tubes harder. 12AX7, 12AT7, 12AY7 or 5751 are all good candidates for the PI position, but it is the 12AX7 that will drive the power tubes hardest in a guitar amp, even when the supporting circuitry is optimised for the 12AT7 (lower value plate resistors & larger value tail resistor). Think of the amps that Leo changed over from a 12AX7 to 12AT7 phase inverter (pro, showman, tremolux etc, etc), the 12AT7 PI amps exhibit more clean headroom from the power amp than their earlier 12AX7 PI counterparts. Cheers
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Thank you, Ivan...i suppose that i am perhaps "hung up" on the higher transconductance of the 12AT7 in comparison to the 12AX7.

I want you to know (and this includes the rest of you that have commented) that i sincerely appreciate the education in this regard.

Let me say that the ECC823 is pure genious in the V1 position of these DSL40C amps. I believe it was @syscokid, @Goldmember, and @Hackmaster that suggested this "hybrid" tube to me.

These amps have way too much gain in stock form, so much so that the upper 2/3rds of the gain knob is largely unusable.

The JJ5751 in V2 and V3 gives the gain control a more linear functionality. The gain is still quite pronounced, but not as "peaky" or extreme.

Conversely, a 5751 or other lower gain tube in V4 has a similar effect of reducing the "harshness" of the gain structure and giving the amp a smoother, less "brittle" tone.

I am eager to try a 12AT7 in V4, but have zero in stock, so i have to wait for replacements to arrive from Amplified Parts.

I read an article by Myles Rose where he liked to put a Sovtek 12AX7LPS in V4 despite lower gain tubes in the first 3 slots. This seemed very odd to me to have the highest gain tube in the very last position.

Any idea why this would be a suggestion???

Also, Is there any risk of damaging the DSL40C by long term use (very near 3/4 knob volume with volume controlled by a FV30L in the FX loop) with a 12AT7 in V4???

I have a couple of experiments that i would like to try in V4...
 
So, let me re-direct this question...

What would the sonic effect(s) be between using a 12AT7, a B759 Gold Lion (ultra-high gain 12AX7) and a Sovtek 12AX7LPS in position V4 with a ECC823/5751/5751 V1-V3 rollout in a DSL40C???
 
Robert Herndon said:
So, let me re-direct this question...

What would the sonic effect(s) be between using a 12AT7, a B759 Gold Lion (ultra-high gain 12AX7) and a Sovtek 12AX7LPS in position V4 with a ECC823/5751/5751 V1-V3 rollout in a DSL40C???
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Have your ears answer that my friend, I have rolled mine out with the help of both you and Cadorman, and I am still loving it’s stability and the tones I am getting 8 months later, but I also am not in your position, with the band and music you are playing.
And if Scott has not gotten rid of the other Dsl40c I would have changed it as well..
 
Mitch Pearrow SJMP said:
Have your ears answer that my friend, I have rolled mine out with the help of both you and Cadorman, and I am still loving it’s stability and the tones I am getting 8 months later, but I also am not in your position, with the band and music you are playing.
And if Scott has not gotten rid of the other Dsl40c I would have changed it as well..
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Just want to do a little recon before buying more tubes...
 
ivan H said:
Without getting technical (which I've had far too much to drink for at the moment), no, I wouldn't expect it to hit the power tubes harder. 12AX7, 12AT7, 12AY7 or 5751 are all good candidates for the PI position, but it is the 12AX7 that will drive the power tubes hardest in a guitar amp, even when the supporting circuitry is optimised for the 12AT7 (lower value plate resistors & larger value tail resistor). Think of the amps that Leo changed over from a 12AX7 to 12AT7 phase inverter (pro, showman, tremolux etc, etc), the 12AT7 PI amps exhibit more clean headroom from the power amp than their earlier 12AX7 PI counterparts. Cheers
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Very interesting. I'm going to try the very high gain Genelex B759 Gold Lion in V4 and a ECC81 as well and see which of them i like better.
 
Today is my all-day music day. This means I have nothing on schedule but just to mess around with musical things.

The singer from Fire Control is coming over to record some vocals, and I will do some backing vocals.

This morning, I did another tube swap on the amp. I kept the ECC-823 in V1, but then swapped a JJ ECC83S into V2 with a 5751 in V3 and V4. Man, what a neat tone!!!!
 
Loud, percussive, and yet totally controllable at extreme volume levels. This has a very close tone to Pete Willis's rhythm tone in "foolin" - its a very clean, overdrive sound...

2015 DSL40C - No Modifications To Circuits

"Lead 2"

Tone Shift "IN"

Jensen Jet Tornado 100 Watt Neodymium Speaker

V1 ECC823
V2 ECC83S
V3 JJ 5751
V4 JJ 5751

Gain: 1/2
Volume: 8
Treble: 7
Mids: 9
Bass: 7
Pres: 5
Reso: 9
 
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Robert Herndon said:
I read an article by Myles Rose where he liked to put a Sovtek 12AX7LPS in V4 despite lower gain tubes in the first 3 slots. This seemed very odd to me to have the highest gain tube in the very last position.

Any idea why this would be a suggestion???

Also, Is there any risk of damaging the DSL40C by long term use (very near 3/4 knob volume with volume controlled by a FV30L in the FX loop) with a 12AT7 in V4???

I have a couple of experiments that i would like to try in V4...
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I would think then that the volume would stay the same but it would be lower gain from tubes V1 - V3 as V4 is the PI. Shoildn't really affect the gain structure that much as the first tubes are the ones that are cascaded.
No damage I shouldnt think at all. Just power tube burn out.
 
Robert Herndon said:
I read an article by Myles Rose where he liked to put a Sovtek 12AX7LPS in V4 despite lower gain tubes in the first 3 slots. This seemed very odd to me to have the highest gain tube in the very last position.
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A long time ago... I read that 12AX7's with long plates like the Sovtek 12AXTLPS don't fare well on combos because of the effects of the nearby speaker cranking away. Is this a myth, or not? Anybody?
 
syscokid said:
A long time ago... I read that 12AX7's with long plates like the Sovtek 12AXTLPS don't fare well on combos because of the effects of the nearby speaker cranking away. Is this a myth, or not? Anybody?
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Could be, but I am not certain. I use all short plates as a rule, although I did consider the 12ax7lps.
 
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