That's pretty much funny thing cause other folks tell about JJ tubes these were rather midrange focused.
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Preamp tube advice needed: tight and focused
- Thread starter Inconnu
- Start date
In my SVP pro preamp there is only very little (if any) noticeable difference between:
Tronal
Siemens
Valvo
Telefunken
Sovtec xxxWA
Sovtec xxxWB
JJ
RCA
If I'd ask a question to the TB-forum for suggestion on tubes which one lets this preamp sound just like:
more bright
mellow
soft
midrange focused
smooth
bassy
grindy
carrots
...???
I'd get always nearly the same sound back with this preamp, no matter what tube in particular (NOS or current production tubes) was suggested by some "experts"
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If the tube circuit inside the bass preamp was designed to meet hifi demands? Probably its not!
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- Feb 12, 2006
- 61,035
- 5
- 220,937
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
There are ways to intentionally linearize or normalize the response of many of the preamp tube variables, by doing this, all players get performance closer to what the designer intended.
Right!
And sometimes it happens that players "think" they could "break thru" those designed linearization (done by the designer) and put tubes such as 12AU7 or something different in it where a 12AX7 should be.
Those inappropriate "mods" are done with svp pro preamp frequently.
When I bought my svp pro used, the preamp was "modded" by the preowner with an inappropriate tube for V4
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As others have indicated, it's going to depend on the circuit, and also your specific goals. Some circuits respond to tube rolling and some do not. Usually circuits that do respond produce rather subtle changes. But sometimes a subtle change can be very beneficial IMHO.
The tube I suggest for your stated goals is the current production Mullard ECC83. This tube surprised me the first time I rolled it. In my experience it tends to pump up and extend the lows a bit, but it also seems to tighten them. I have found no other tube that produces this result. This tube also seems compressed or soft in the high mids, but it has plenty of air above that. The softness is centered in the frequency range where you get fret rattle and clank.
The other tubes I have rolled with big lows tend to be sort of loose, woolly, and unfocused. I would say the Sovtek 12AX7LPS sounds very similar to the Mullard ECC83 in the mids and highs. The Mullard it tighter and more focused down low, and the Sovtek seems looser and woolier.
I totally understand my so many people love the Tung Sol, but in my experience it tends to be strong and super punchy in the high mids. So it tends to emphasize fret rattle and clank rather than suppress it.
The combination of tubes I have used most in bass amps is a Mullard ECC83 in V1 and a JJ ECC803S pretty much everywhere else. The JJ sounds fairly even. It does not seem to reach as high or low as the Mullard, and it's a bit lean in the lows. It also tends to sound rather tight and controlled and have a bit of what I call a harmonic shimmer in the mids. I think it may sort of push back gently on some of the Mullards tendencies. For my taste the two together often provide gestalt.
Tubes respond to the circuit, so you may get totally different results. Also not every amp benefits from the same recipe. I have found it beneficial to use totally different tubes in some of my bass amps. Also I prefer different tubes in guitar amps.
Good Luck!
Start with a preamp that is smooth and detailed to your liking?
Yup, I mean actual tube, not a tube device. I’ve tried a different 12ax7 in a preamp pedal and it changed the sound quite a bit, I want to try to go further in that direction.OP asked about a preamp tube... most of the answers are about tube preamps....
@Inconnu, could you clarify - are you asking about a replacement tube for a preamp you already have? If so, what is the preamp?
Without knowing what amp you have anything is just a guess. I typically like Tungsol and JJ but preferred GE or EHX in my walkabout. My Traynor really shines with Tungsol. I have most every 12ax7 so within reason new and NOS and have a good idea what most sound like but different circuits really do shine more with some tubes compared to others.
Cheap and OK at best. The variable impedance knob is the best thing about it. But what does this have to do with the OP question about tube recommendations for their amp?
So that suggests the circuit is fairly sensitive to the tube's characteristics. Picking a tube by how it sounds in a different circuit may not give the same results in your preamp pedal. Perhaps if you shared the exact pedal you have, someone will have experience with different tubes in it.
So, really, the only thing you can do is experiment. 12AX7, 12AU7, 12AT7, 12AY7, ECC81, ECC83, and many others all have compatible pin connections , so you can try them. Do you have a guitarist friend with a tube amp who maybe has some spare tubes to try? Or is adventurous enough to let you borrow some tubes from their amp as an experiment?
Obligatory caution: tube circuits usually involve voltages that can cause injury or even death. Tubes get dangerously hot when operating. Disconnect power and let everything cool down before swapping tubes!
Methinks you don't give contemporary preamp designers enough credit. And whatever the circuits, that is not the point. The point is that hi-fi or audiophile applications of any particular preamp tube for its linearity, frequency response, headroom, and low noise is the same as what the OP is looking for.
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Sorry! I forgot to say, this is what I use with the ART PRO MPA II, and it’s not ok, it’s awesome
:Matched Pair PSVANE 12AX7-S Vacuum Tubes.
Replace ECC83 12AX7 12AX7B TUBE
[This invalid link has been removed]
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Welcome to the bottomless rabbit hole 
You could spend more than a small fortune experimenting with "non obtainium" NOS so will confine my recommendation to one current production: Tung-Sol 12AX7 gold pin. I have used them in a few amps and always found them to deliver what you described.
You could spend more than a small fortune experimenting with "non obtainium" NOS so will confine my recommendation to one current production: Tung-Sol 12AX7 gold pin. I have used them in a few amps and always found them to deliver what you described.
- Feb 12, 2006
- 61,035
- 5
- 220,937
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
The point is that the tube circuits used in the hi-fi world are often quite different than in the bass/guitar amp world. The circuitry in the hi-fi world often maximize the linearity of a tube, while the circuit in the bass/guitar amp world typically attempt to do mostly the polar opposite.
This is why conclusions can't be drawn between the two types of equipment. (I have designed in both worlds, the techniques are often really different).
Yes, the JJ ECC83S often seems very mid focused to me. It's so extreme that it gives me the impression of limited bandwidth. My perception is that it has slightly lower than average gain for the tube type and often seems to have kind of a gritty quality, like it's on the verge of breaking over into distortion. I have pulled several from my bass amps during tube rolling. There are still a few lurking, and the amps sound good enough that I am in no hurry to replace them.
I have used a couple of the pulls to "soften" some of my vintage, non-master guitar amps, so they work a little better at low volume in my basement. Amps are a Marshall JCM 800 1959 Super Lead and a JMI era Vox AC30 with top boost. The ECC83S seems to take away some of ice pick in the ear effect
. So in this sense, it seems useful at softening the sound.If I were using either amp as intended, I might choose a Tung Sol 12AX7.
I wonder what might happen (soundwise) if those tubes were placed in a fender bassman typical circuit with large cathode R bypassing C equal to ~22uFSorry! I forgot to say, this is what I use with the ART PRO MPA II, and it’s not ok, it’s awesome
Matched Pair PSVANE 12AX7-S Vacuum Tubes.
Replace ECC83 12AX7 12AX7B TUBE
View attachment 4756665
[This invalid link has been removed]
I have hifi all tube setup and honestly these NOS or high priced preamps tubes do not make a difference .Of course they need to be tested and you will get duds out of current production. Maybe vintage tube condenser microphones can benefit but I only heard that on the internet and do not own or have handled a vintage condenser mic.
Tube preamps are not going to give you really tight, not tighter than a JFET for example. That is why Dumble for example provides you with a JFET input for his amps. Tight tube pre is all about design not voodoo 12Ax7
My practical answer for bass guitar, is to get an Avalon U5 preamp. not too crazy price wise and has enough flexibility. I do not own one but had the pleasure of playing a few times connected to a Bergantino powered cab. Very tube like. I have Demeter tube preamp and the Avalon is way better, even though my Demeter had a vintage 12Ax7. I tired tube rolling on the Demeter and no difference except that some vintage 12AX7 where noisier..
Same guy also had a Summit Audio, a newer Demeter, Reddi and FX2 -- and the Avalon though not tube(I found that out later ) was the best sounding of all of them.
Tube preamps are not going to give you really tight, not tighter than a JFET for example. That is why Dumble for example provides you with a JFET input for his amps. Tight tube pre is all about design not voodoo 12Ax7
My practical answer for bass guitar, is to get an Avalon U5 preamp. not too crazy price wise and has enough flexibility. I do not own one but had the pleasure of playing a few times connected to a Bergantino powered cab. Very tube like. I have Demeter tube preamp and the Avalon is way better, even though my Demeter had a vintage 12Ax7. I tired tube rolling on the Demeter and no difference except that some vintage 12AX7 where noisier..
Same guy also had a Summit Audio, a newer Demeter, Reddi and FX2 -- and the Avalon though not tube(I found that out later ) was the best sounding of all of them.
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