Dumble Preamp tubes

[stiltamp]

Hi,

what are the best sounding tube brand combinations for the Dumble preamp.
Are there different combinations depend on the Dumple types.

Manfred

[Guitarman18]

Hi stiltamp,

Welcome to the site.

I think the JJ's work really well in the D style amp and I think there are quite a few members here who also favour them. EH sounded too bright for me. Use a balanced one in the PI.

Hope this helps.

Cheers, Paul.

[selloutrr]

call eurotubes and talk with them about what you want they can hand select tubes to compliment your amp and playing style.

[heisthl]

IMHO it depends on how the amp is built and whose ears are hearing it - I've never found a situation where a JJ preamp tube was the best choice. No flames please I have no agenda or favorites.

[hairyandy]

I like Telefunkens in my D'Lite but they aren't cheap.

Andy

[sidehatch]

Of course I dont have a real dumble but I have owned 2 straight copies and now have a redplate in front of me and the Carr thats been modded with a dumble lead channel.

In every amp I have ever owned RCA's sound best to these ears. Fenders, Carr, two rock didnt matter. RCA's sound best to me. Last week I did a comparison with a telefunken, Mullard,Rca,Ge, Jan GE, Phillips and a few others. I liked the Telefunken the least in the Carr lead channel. Very Midrangey and boxy.

A few days ago I tried all them in the Redplate(Heisthl's company)

I found that they all sounded at least 20% WORSE than the EH tubes that came in it. He has 3 EH's and 1 sovtek LPS in the phase inverter.

So what I have learned(an I may be way way off) is that in a general amp I like RCA's but when someone who has big ears(like Heisthl) voices his amp with a particular tube-that's going to sound the best.

Usually tubes with me are kinda like " wait, I think I can tell a difference", "this one might have better mids" "go back to the first one" etc. but in theRedplate it was "whoa!! the EH is fatter, warmer,much louder,more present and just better" You could have told us that it was a rare $200 NOS gem and I would have believed it.

I tried the EH's in my fenders and was less impressed and went back my my stash of Rca's.

What do you guys think? Anyone else encounter this?

[Bob-I]

I've tried a ton of tubes in my Dumble clones, here's my take...

JJ - bright, plenty of gain and well balanced. Gold pin seem a tad more complex in the mids

EH - Very bright, balance out an overly dark amp well. Consistent.

Mullard Reissue - dark and smooth. Consistent

Tung-Sol reissue - Not unlike the Mullard in charactor but a tad less interesting in the mids

Sovtek 12AX7LPS - My choice for the PI. No need to get a balanced tube for this location, use the PI trimmer. Not real good for V1 and V2 but acceptable.

Tech Tube - Interesting design but bright and lacking bottom end. I like it in V1 for a nice bright clean tone but not very good for V2 or PI. I'm only tried one though.

RCA NOS - really great for V2 with the Tech Tube in V1. Nice complex mids, big fat bottom end and good highs.

GE NOS - Jury's still out but it seems nice especally in the mids.

[bluesfendermanblues]

I don't have experience with a lot of different tube brands in my amp, but heres my findings with JJ and EH tubes.

I have tweaked my amp around JJs in V1 and V2 (V3 is a Sovtek 12axtwa) and tried a couple of EH in the first two positions, just to see if this would improve tone somehow, and found the EH's to be much brighter than the JJs - not just a tad, but much brighter.

Did a check on the voltage and found that with a JJ in V1, the voltage was lower (190V on V1) with the JJ and higher with the EH (203V on V1). Hence, the JJ must draw more current. Compared the 4 JJs and 5 EHs I had just purchased and the voltage difference was consistent.

Perhaps, the JJs and EHs would sound more alike, if the PSU string was adjusted to 190V for the EHs.

[stiltamp]

Hi,

thank's a lot to all for the competent replies.
I intend to build a clone.

Which type of Dumple got Robben Ford?

Great Forum!

regards
Manfred

[Structo]

I have a nos Raytheon in V1 and a late generation Chinese tube in V2.

For the PI, not sure what is in there at the moment but I just rolled through some tubes until I liked what I heard.

Keep in mind, it also matters what power tubes you are using as well, as to how the preamp tubes sound.

[Tonegeek]

Of course I dont have a real dumble but I have owned 2 straight copies and now have a redplate in front of me and the Carr thats been modded with a dumble lead channel.

In every amp I have ever owned RCA's sound best to these ears. Fenders, Carr, two rock didnt matter. RCA's sound best to me. Last week I did a comparison with a telefunken, Mullard,Rca,Ge, Jan GE, Phillips and a few others. I liked the Telefunken the least in the Carr lead channel. Very Midrangey and boxy.

A few days ago I tried all them in the Redplate(Heisthl's company)

I found that they all sounded at least 20% WORSE than the EH tubes that came in it. He has 3 EH's and 1 sovtek LPS in the phase inverter.

So what I have learned(an I may be way way off) is that in a general amp I like RCA's but when someone who has big ears(like Heisthl) voices his amp with a particular tube-that's going to sound the best.

Usually tubes with me are kinda like " wait, I think I can tell a difference", "this one might have better mids" "go back to the first one" etc. but in theRedplate it was "whoa!! the EH is fatter, warmer,much louder,more present and just better" You could have told us that it was a rare $200 NOS gem and I would have believed it.

I tried the EH's in my fenders and was less impressed and went back my my stash of Rca's.

What do you guys think? Anyone else encounter this?

I like the RCA's too. Currently i am using old GT's in my HRM type preamp, but I like the EH almost as much. I have an RCA in the PI. I used to be all over the Sovtek LPS in the PI (like so many others) but when i swapped it with an old RCA, it just warmed everything up. The LPS is too hard sounding in any other position on this amp, but I have used it in other amps successfully to get some oomph on the front end and to tame spikey highs. Now the only reason I even thought of swapping out the LPS is that LordValve claims an LPS is not a good choice for the PI. He claims it will breakdown evetually and I believe he said it was that it cannot take the grid to cathode voltage differential encountered in a PI. I have not heard of issues from any users here, but maybe in other designs it may be true. Interesting though is that I can find no specs on a Sovtek 12ax7 in that regard. LV wrote directly to me when I asked for clarification on his statement so he is quite convinced this is a problem. Anyhow, for me, I just like the sound of the RCA better. I have not tried JJs in this amp other than the EL-34s which I like a lot.

[Structo]

Currently I have a pair of used 6L6 RCA blackplates in my amp (50 watt).

Yes, the hype is true about these tubes. I couldn't believe it the first time I heard them.

[heisthl]

the only reason I even thought of swapping out the LPS is that LordValve claims an LPS is not a good choice for the PI. He claims it will breakdown evetually and I believe he said it was that it cannot take the grid to cathode voltage differential encountered in a PI. I have not heard of issues from any users here, but maybe in other designs it may be true. Interesting though is that I can find no specs on a Sovtek 12ax7 in that regard. LV wrote directly to me when I asked for clarification on his statement so he is quite convinced this is a problem.

In a typical D-style PI you see 12 volts on the grid and 56 volts on the cathode, so a 44 volt difference. On a Fender 47k plate PI you see a much bigger difference. I wonder if he was talking about 44 volts being a problem? I have been using that tube in the PI position exclusively with no issues.

[skeezbo]

I read somewhere that you weren't supposed to use the LPS as V2 in Fender tweed or Marshall style amps because the side that had the cathode follower couldn't take it. Maybe it shouldn't be used as a split-load inverter either. I've never used one, but I hear they sound good.


Skeezbo

[Structo]

Pardon my ignorance, but what is a LPS?

Is it long plate?

It's funny how subjective we can be about tubes and all aspects of our amplifiers.

I for one found most of my amps sounded rather lifeless withe the JJ preamps.

But in my Carvin Belair, they sounded pretty good. Go figure.

Last time I was in my D'Lite I had 53v on the PI cathodes and 34 on the grids.
I believe that was with an EH in the PI spot.

Henry, I think that is good that you tune your amps to current production tubes.
Because one of these days, there won't be any old tubes left.