DC-5 tubes

[Kage]

Hi, new to the board and just got my first Mesa, a DC-5. I'm looking over the preamp tubes and I'm hoping to find out what each of the tubes does. Is V1 the one closest to the input jack? Someone previously had put a JJ ECC81 in the fourth socket from the jack, I'm thinking that's probably something to do with either the reverb or the effects loop? So far I'm digging the amp but I think it could be better with some better tube choices.

 

[Beasleyboy]

Ya dude I just got a dc-10 head I'm looking to retube and I'd be interested in some info on this too

 

[inertia]

http://thetubestore.com/

I found that website. I don't know if anyone's used them to buy tubes. But they seem to talk the talk 8)

 

[Casper]

Dougstubes and a company called Eurotubes both have "tone packages" for the DC5. I just got a new set of JJ/Teslas from Bob at Eurotubes..I have found that JJs are the quietest tubes for this amp..(my opinion, anyway). Doug will sell you a mixture of tubes, Bob will sell you JJs. Either is a good choice, but Eurotubes is less expensive.
Hope this helps-
Shaun

 

[MusicManJP6]

JJs sound the best in the DC, F, and Express series amps IMO. They are quieter, cleaner, tighter, and crunchier.

 

[Sixstringpsycho]

im using JJ's in my DC-5 and love it. after alot of experimenting i went with the eurotube "high gain" package they sell for the DC series and I love it. My cleans are vocal and nice and the distortion is liquid and smooth.

 

[MusicManJP6]

im using JJ's in my DC-5 and love it. after alot of experimenting i went with the eurotube "high gain" package they sell for the DC series and I love it. My cleans are vocal and nice and the distortion is liquid and smooth.

Adversely, I just tried a JAN Phillips 12AT7 in V1 and it smoothed out the output volume taper a bit (even more than the volume knob mod) and also added more headroom to the clean channel if my ears are not mistaken... Otherwise it's all JJs in my preamp.

 

[Sixstringpsycho]

im using JJ's in my DC-5 and love it. after alot of experimenting i went with the eurotube "high gain" package they sell for the DC series and I love it. My cleans are vocal and nice and the distortion is liquid and smooth.

Adversely, I just tried a JAN Phillips 12AT7 in V1 and it smoothed out the output volume taper a bit (even more than the volume knob mod) and also added more headroom to the clean channel if my ears are not mistaken... Otherwise it's all JJs in my preamp.

Really? smoothed it our even more.....that is worth a try, good info

 

[MusicManJP6]

im using JJ's in my DC-5 and love it. after alot of experimenting i went with the eurotube "high gain" package they sell for the DC series and I love it. My cleans are vocal and nice and the distortion is liquid and smooth.

Adversely, I just tried a JAN Phillips 12AT7 in V1 and it smoothed out the output volume taper a bit (even more than the volume knob mod) and also added more headroom to the clean channel if my ears are not mistaken... Otherwise it's all JJs in my preamp.

Really? smoothed it our even more.....that is worth a try, good info

I'm pretty sure it did, but around the same time I swapped that tube I also changed my cab config from one cab using the 8ohm out to two cabs using the 4ohm outs. This may have caused a volume drop that I perceived as a smoother taper. Report back with your opinion on an AT7's effect on the taper and i'll swap the tubes again and see if i'm mistaken as well...

 

[lockbody]

Try a AT7 in the PI spot (V6) for some more headroom, too.

 

[MusicManJP6]

Try a AT7 in the PI spot (V6) for some more headroom, too.

For MORE headroom? I tried this and my clean channel had no headroom at all. I thought a lower gain tube in this slot made the amp breakup earlier therefore decreasing headroom. Correct me if i am wrong, but that is what I have read and experienced.

 

[lockbody]

Try a AT7 in the PI spot (V6) for some more headroom, too.

For MORE headroom? I tried this and my clean channel had no headroom at all. I thought a lower gain tube in this slot made the amp breakup earlier therefore decreasing headroom. Correct me if i am wrong, but that is what I have read and experienced.

Really? Hmmm, I tried it and liked it, but didn't go back and compare and contrast between it and the 12ax7. Maybe there isn't more headroom after all, but I like it anyway.

 

[lockbody]

Try a AT7 in the PI spot (V6) for some more headroom, too.

For MORE headroom? I tried this and my clean channel had no headroom at all. I thought a lower gain tube in this slot made the amp breakup earlier therefore decreasing headroom. Correct me if i am wrong, but that is what I have read and experienced.

PI stuff ('cause I didn't know any of this):

When you push your amp hard it is not as much the output tubes distorting as it is the phase inverter breaking down and distorting. We are talking output stage distortion here. We are not talking about how you may have messed up the signal with preamp tube distortion and compression already. The phase inverter may be the hardest worked tube in most amps. I cannot begin to count the times when I have found phase inverters that were long past their service life. When you change your output tubes change that phase inverter. At the least change it every other output tube change.
Many folks think that when they want to have their amp have more clean headroom they can insert a 12AT7 in place of the 12AX7. Very true. (By the way, the 12AT7 in a first gain stage is an awful tone generator in a guitar amp. If you want to drop front end gain use a 5751 (gain of 60-70) or a 12AY7 (gain of 40). The 12AY7 was the first gain stage in the classic Fender Tweed Bassman, Deluxe, etc.
Going from a 12AX7 to a 12AT7 in the PI (phase inverter) will yield a change in output tube distortion, touch, and output dynamics in most amps. Is this because the gain is lower in the 12AT7? 10% yes perhaps. The lower gain is a factor but the larger factors are:
• We have almost 10 times the current available to drive the output tubes before the phase inverter starts to break down.
• We have a transconductance of 5500 vs 1600 of the 12AX7. Keeping this simple, it means it takes a lot less input signal for a given output signal.

and

Q. What does the Phase Inverter do and what will swapping a 12at7/12au7 do for it ?

A. The phase inverter splits the signal to go to the power tubes. It is not a part of the preamp, but of the power amp. If you have a lower gain tube in the PI, then the power tubes receive a lower signal. You don't notice this in volume, but more in terms of sound. There's a lot more "compression" in a lower gain tube, meaning that the sound is tighter.

This also affects the presence control, as that usually feeds back from the OPT into the phase inverter stage.

 

[MrMarkIII]

Hi, new to the board and just got my first Mesa, a DC-5. I'm looking over the preamp tubes and I'm hoping to find out what each of the tubes does. Is V1 the one closest to the input jack? Someone previously had put a JJ ECC81 in the fourth socket from the jack, I'm thinking that's probably something to do with either the reverb or the effects loop? So far I'm digging the amp but I think it could be better with some better tube choices.

Schematics for DC's here:

http://schematicheaven.com/mesaboogie.htm

 

[MusicManJP6]

Try a AT7 in the PI spot (V6) for some more headroom, too.

For MORE headroom? I tried this and my clean channel had no headroom at all. I thought a lower gain tube in this slot made the amp breakup earlier therefore decreasing headroom. Correct me if i am wrong, but that is what I have read and experienced.

PI stuff ('cause I didn't know any of this):

When you push your amp hard it is not as much the output tubes distorting as it is the phase inverter breaking down and distorting. We are talking output stage distortion here. We are not talking about how you may have messed up the signal with preamp tube distortion and compression already. The phase inverter may be the hardest worked tube in most amps. I cannot begin to count the times when I have found phase inverters that were long past their service life. When you change your output tubes change that phase inverter. At the least change it every other output tube change.
Many folks think that when they want to have their amp have more clean headroom they can insert a 12AT7 in place of the 12AX7. Very true. (By the way, the 12AT7 in a first gain stage is an awful tone generator in a guitar amp. If you want to drop front end gain use a 5751 (gain of 60-70) or a 12AY7 (gain of 40). The 12AY7 was the first gain stage in the classic Fender Tweed Bassman, Deluxe, etc.
Going from a 12AX7 to a 12AT7 in the PI (phase inverter) will yield a change in output tube distortion, touch, and output dynamics in most amps. Is this because the gain is lower in the 12AT7? 10% yes perhaps. The lower gain is a factor but the larger factors are:
• We have almost 10 times the current available to drive the output tubes before the phase inverter starts to break down.
• We have a transconductance of 5500 vs 1600 of the 12AX7. Keeping this simple, it means it takes a lot less input signal for a given output signal.

and

Q. What does the Phase Inverter do and what will swapping a 12at7/12au7 do for it ?

A. The phase inverter splits the signal to go to the power tubes. It is not a part of the preamp, but of the power amp. If you have a lower gain tube in the PI, then the power tubes receive a lower signal. You don't notice this in volume, but more in terms of sound. There's a lot more "compression" in a lower gain tube, meaning that the sound is tighter.

This also affects the presence control, as that usually feeds back from the OPT into the phase inverter stage.

Wow. That was a good read. I stand corrected! Man, maybe it was the tube that went bad that was causing my amp to sound like it had no headroom. Now i'm confused. I had alot going on yesterday with my amp. I'll have to do some tube swaps again and keep everything else constant for a better comparison. Thanks for the info!

 

[Kage]

Hi, new to the board and just got my first Mesa, a DC-5. I'm looking over the preamp tubes and I'm hoping to find out what each of the tubes does. Is V1 the one closest to the input jack? Someone previously had put a JJ ECC81 in the fourth socket from the jack, I'm thinking that's probably something to do with either the reverb or the effects loop? So far I'm digging the amp but I think it could be better with some better tube choices.

Schematics for DC's here:

http://schematicheaven.com/mesaboogie.htm

Interesting, let me see if I understand correctly. Both channels are affected by V1, the Rhythm channel also runs through V4 while the Lead runs through V2 and V3. V5 is for the reverb and V6 is the phase inverter. Is that right? That may explain that ecc81 in V4.

 

[MusicManJP6]

Hi, new to the board and just got my first Mesa, a DC-5. I'm looking over the preamp tubes and I'm hoping to find out what each of the tubes does. Is V1 the one closest to the input jack? Someone previously had put a JJ ECC81 in the fourth socket from the jack, I'm thinking that's probably something to do with either the reverb or the effects loop? So far I'm digging the amp but I think it could be better with some better tube choices.

Schematics for DC's here:

http://schematicheaven.com/mesaboogie.htm

Interesting, let me see if I understand correctly. Both channels are affected by V1, the Rhythm channel also runs through V4 while the Lead runs through V2 and V3. V5 is for the reverb and V6 is the phase inverter. Is that right? That may explain that ecc81 in V4.

That's correct. I have a gold pin ECC83 in V4 to keep the clean channel smooth.

 

[MrMarkIII]

Hi, new to the board and just got my first Mesa, a DC-5. I'm looking over the preamp tubes and I'm hoping to find out what each of the tubes does. Is V1 the one closest to the input jack? Someone previously had put a JJ ECC81 in the fourth socket from the jack, I'm thinking that's probably something to do with either the reverb or the effects loop? So far I'm digging the amp but I think it could be better with some better tube choices.

Schematics for DC's here:

http://schematicheaven.com/mesaboogie.htm

Interesting, let me see if I understand correctly. Both channels are affected by V1, the Rhythm channel also runs through V4 while the Lead runs through V2 and V3. V5 is for the reverb and V6 is the phase inverter. Is that right? That may explain that ecc81 in V4.

I guess so. I've heard comments here that the DC rhythm sound is not as squeaky clean as some would like, so it makes sense that one might try a lower gain tube at that point. It's interesting to me that the rhythm channel is set up like a Fender, with the tone controls BEFORE the gain, and the lead channel is Marshall-y, with the tone stack AFTER the gain.

 

[MusicManJP6]

I guess so. I've heard comments here that the DC rhythm sound is not as squeaky clean as some would like, so it makes sense that one might try a lower gain tube at that point. It's interesting to me that the rhythm channel is set up like a Fender, with the tone controls BEFORE the gain, and the lead channel is Marshall-y, with the tone stack AFTER the gain.

Hmmm... a gold pin ECC may be warmer, but prob has about the same gain - i'll have to try an AT7 in V4 and see what that does for the clean channel instead... I love having some different preamp tubes around to swap in and out!

 

[Kage]

Here's a goofy question since we were looking at schematics. It's an older version of the DC but the person I got it from only had the new version of the 2-button footswitch. It would change the channel used in that jack but won't do anything when I have it plugged into the back for the jack on the EQ/Rev. Is there a way to rewire that switch to convert it to the older footswitch?

This is the one I have http://mesa.stores.yahoo.net/fcdcn.html

This is the one I should have had. http://mesa.stores.yahoo.net/fcrg.html