DC-5 mod/tubes question

[blacklight_uk]

I love the sound i'm getting from my DC-5 at the moment. After spending ages tweaking it i've actually found that with my setup it sounds great the way Randall's boys set it up - everything on 5 with the presence/master/output/reverb set to the room.

What i want to know though is which power tubes the DC-5 can handle. Will it only accept 6L6s? The reason i ask is that i'd like to experiment and get to know my amp even better. I feel that this is a life-long amp for me


In terms of mods, is there any way to make the pull boost circuit footswitchable? I realise this would be fairly complicated but having a clean, crunch and lead channel with the footswitchable GEQ would get rid of a couple of pedals from my board and give me a bit more diversity. As it stands i never use the pull boost even though i absolutely love the tone from it because i need a clean channel.

Cheers guys,
Josh

 

[Fxrs]

To use EL-34's(I think actually E34L's) you can have a switch installed, other than that, I think your only alternative is 5881's. The pull boost can be made footswitchable, but I couldn't do it myself, I don't know what your skill level is.

 

[edward]

I love the sound i'm getting from my DC-5 at the moment. After spending ages tweaking it i've actually found that with my setup it sounds great the way Randall's boys set it up - everything on 5 with the presence/master/output/reverb set to the room.

What i want to know though is which power tubes the DC-5 can handle. Will it only accept 6L6s? The reason i ask is that i'd like to experiment and get to know my amp even better. I feel that this is a life-long amp for me


In terms of mods, is there any way to make the pull boost circuit footswitchable? I realise this would be fairly complicated but having a clean, crunch and lead channel with the footswitchable GEQ would get rid of a couple of pedals from my board and give me a bit more diversity. As it stands i never use the pull boost even though i absolutely love the tone from it because i need a clean channel.

Cheers guys,
Josh

Hi Josh,

I recall one person long ago said he had his tech do a footswitchable pull boost. I had asked him to get me specifics, and he said he would. That was well over a year ago, IIRC. Since then, I've found that if I need an "in-betweener" tone, I just hit a pedal on the clean channel for that "3rd channel" voice.

As for power tubes, unless you want to get into a fairly involved mod, you can use only 5881s aside from 6L6s. Keep in mind, though, that there are lots of diff tubes out there that will get you different tone and dynamics ...no "need" to swap out of the family. Moreover, you can (arguably) achieve more tonal differences with preamp tube swaps. Try different 12AX7s as well as 12AT7s and 5751 in the various spots and see what you like ...trust your ears.

Edward

 

[tetsubin]

I love the sound i'm getting from my DC-5 at the moment. After spending ages tweaking it i've actually found that with my setup it sounds great the way Randall's boys set it up - everything on 5 with the presence/master/output/reverb set to the room.

What i want to know though is which power tubes the DC-5 can handle. Will it only accept 6L6s? The reason i ask is that i'd like to experiment and get to know my amp even better. I feel that this is a life-long amp for me


In terms of mods, is there any way to make the pull boost circuit footswitchable? I realise this would be fairly complicated but having a clean, crunch and lead channel with the footswitchable GEQ would get rid of a couple of pedals from my board and give me a bit more diversity. As it stands i never use the pull boost even though i absolutely love the tone from it because i need a clean channel.

Cheers guys,
Josh

Hi Josh,

I recall one person long ago said he had his tech do a footswitchable pull boost. I had asked him to get me specifics, and he said he would. That was well over a year ago, IIRC. Since then, I've found that if I need an "in-betweener" tone, I just hit a pedal on the clean channel for that "3rd channel" voice.

As for power tubes, unless you want to get into a fairly involved mod, you can use only 5881s aside from 6L6s. Keep in mind, though, that there are lots of diff tubes out there that will get you different tone and dynamics ...no "need" to swap out of the family. Moreover, you can (arguably) achieve more tonal differences with preamp tube swaps. Try different 12AX7s as well as 12AT7s and 5751 in the various spots and see what you like ...trust your ears.

Edward

It wasn't me, but my pull boost (DC-5) was also modded to be footswitchable by the former owner of the amp. Unfortunately he didn't get a trim-pot for the volume installed. Right now the volume jump from non-boost to boost is just too high to be usable as a 3rd channel. The mod itself is very easy to do AFAIK.

 

[blacklight_uk]

Thanks guys. Hmm i might have to give some 5881s a go you know but i was thinking of doing a full retube anyway since i dont know when the last owner replaced them.

What are the main differences between 12AX7s and 12AT7s?

Also it'd be great to get any more info on this mod. I'm excited to know that it's possible at least and that others have had it done.

 

[tetsubin]

Thanks guys. Hmm i might have to give some 5881s a go you know but i was thinking of doing a full retube anyway since i dont know when the last owner replaced them.

What are the main differences between 12AX7s and 12AT7s?

Also it'd be great to get any more info on this mod. I'm excited to know that it's possible at least and that others have had it done.

As far as the mod is concerned, there's no more info: What else would you want to know?? Just bring your amp to your tech and have it modded. (Bring the schematic to be on the safe side.)

 

[edward]

Thanks guys. Hmm i might have to give some 5881s a go you know but i was thinking of doing a full retube anyway since i dont know when the last owner replaced them.

Remember that all tubes will sound slightly different, but "better" or "worse" is still up to you. Retube if you like, but there is no guarantee that the new ones will sound "better" to your ears than what you already have.

What are the main differences between 12AX7s and 12AT7s?

If 12ax7s have a gain value of 100, then:
5751 = 70
12at7 = 60
12ay7 = 50
12au7

But a change in tubes is more than a simple change in gain. Such a change alters the gain and saturation to be sure, but also overall tone, dynamics, and harmonics ..."improvement" or not is up to you. Each tube position is also responsible for a different task, and so will respond differntly from tube swaps. Add to this variable the fact that not only will an at7 sound diff from an ax7, but two diff make at7s can sound different from one another. Then there's current production vs NOS. The bottom line is trust you ears. Make one change, be patient and play it for a couple days, and swap again. And be honest, knowing that you just may end up preferring the one you have in there right now, or maybe that single $95 Mullard FWIW, it took me a while to finally arrive at what I now love as my personal "recipe" ...but that's just me

Also it'd be great to get any more info on this mod. I'm excited to know that it's possible at least and that others have had it done.

Yeah, I'd like to know about this too ...albeit with a volume pot thrown in.

Edward

 

[tetsubin]

The 12AT7 does have totally different specs than a 12AT7, the current handling capacity for example. So putting a 12AT7 in a circuit designed for a 12AX7 means running a 12AT7 at conditions that are not in spec. That accounts for differences in tone too. If you like the change, ok - but it's not a fair comparison, so to speak.

Look for differences in plate current, voltage and dissipation:
http://www.mclink.it/com/audiomatica/tubes/12at7.htm
http://www.mclink.it/com/audiomatica/tubes/12ax7.htm

 

[edward]

The 12AT7 does have totally different specs than a 12AT7, the current handling capacity for example. So putting a 12AT7 in a circuit designed for a 12AX7 means running a 12AT7 at conditions that are not in spec. That accounts for differences in tone too. If you like the change, ok - but it's not a fair comparison, so to speak.

Look for differences in plate current, voltage and dissipation:
http://www.mclink.it/com/audiomatica/tubes/12at7.htm
http://www.mclink.it/com/audiomatica/tubes/12ax7.htm

Correct, and also a very important point that if you have a circuit designed for an ax7, going to an at7 tube in said circuit is safe since the at7 can, by design, handle a higher current draw. But in a circuit designed for an at7, do NOT try an ax7 as this tube is NOT designed to handle the higher current of most typical at7 circuits ...like Fender's reverb circutis, for example.

So while in a SF Fender's reverb that asks for an 12at7, you should stick with that class tube. But in Mesa's reverb designed for a 12ax7, experimenting (for tonal purposes) with an at7 is perfectly safe. All the DC5's preamp tube slots are spec'd for AX7s so trying out an at7 or 5751 is perfectly safe.

Edward

 

[swhiteh3]

It wasn't me, but my pull boost (DC-5) was also modded to be footswitchable by the former owner of the amp. Unfortunately he didn't get a trim-pot for the volume installed. Right now the volume jump from non-boost to boost is just too high to be usable as a 3rd channel. The mod itself is very easy to do AFAIK.

****, a footswitch mod along with a trim control would be hugely useful. I love my DC-5, but I just wish I had a little more control without turning around and tweaking on the amp.

 

[Paul Secondino]

What i want to know though is which power tubes the DC-5 can handle. Will it only accept 6L6s? The reason i ask is that i'd like to experiment and get to know my amp even better. I feel that this is a life-long amp for me


Cheers guys,
Josh

As mentioned, your amp is meant to run with 6l6 tubes and 5881 is an acceptable replacement. The 5881 will have more headroom than the 6L6 and the EQ of it is slightly different. In fact, Suhr uses the 5881 WXT+ from Sovtek in many versions of his OD100 that he sells.

If there is room in your amp, it is possible to use 6550 tubes. This will require you to re adjust your bias either by physically changing out the resistor in front of your bias supply with a more appropriate one or adding a trim pot with a good range. 6550's will draw more current than a 6l6 and likely run darned hot and stress your Output tranny.

Regarding 12AT7's in the preamp section, they do have less gain but they also offer more headroom than a 12ax7 so sometimes, they can be a good change.Some people will try them as a preamp output tube and like the results.

 

[Paul Secondino]

I forgot to mention that you could try EL34's in your amp but they wont draw much current and will cause the bias supply to run cold. This wont hurt the amp but will cause cross over distortion and sound shitty.

If you add a trim pot to the amp, you can then compensate for the cold bias and effectively run El34's. I've never heard any explanation so far as to how using EL34's in place of a 6l6 will actually damage your amp. All reports stated that the tubes will simply run too cold to sound good.