What preamp tubes in the twinjet

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parntz145

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Just wondering if anyone has tried anything different in it that sounded better than the stock ones?
What is the bias for the KT88? I called Bogner to get it and they dont go by ma. Anyone know what the bias is in ma?
 
snider":1gh20dwz said:
parntz145":1gh20dwz said:
Just wondering if anyone has tried anything different in it that sounded better than the stock ones?
What is the bias for the KT88? I called Bogner to get it and they dont go by ma. Anyone know what the bias is in ma?
Click to expand...

36-40 or a tad more is fine
Click to expand...
Thanks. Where did you get this from? I called Bogner and they were of no help. They couldnt even tell me the plate voltage.
 
found this on the internet...

A general rule of thumb is that class AB amplifiers are usually operated at no more than 70% of the maximum plate dissipation of the tube (to account for the higher dissipation that occurs under signal conditions), while true class A amplifiers generally run right at the maximum plate dissipation (the dissipation at full power is lower than the dissipation at idle in a true class A amplifier). For example, the aforementioned EL34 tube has a plate dissipation of 25W, so at 400V class AB operation, it should be biased no higher than (0.7 * 25/400) = 44mA. At 500V class AB operation, it should be biased no higher than (0.7 * 25/500) = 35mA. This doesn't mean you should automatically bias all tubes to 70% of max dissipation! They can be biased at any lower current if desired, and many people prefer a point of around 50% to 60% of the max plate dissipation, which contributes to longer tube life.
 
Agreed....or buy a compu bias which makes all of this very easy for you. Bogner tends to bias their amps very cold. Sometimes to save tube life and sometimes due to the design of the amp. For example the 6L6 20th anniv. XTC is biased cold so it sounds more like an EL34 amp but the 6L6' give the amp more bottom and makes the clean channel better as well as giving the amp a cool woody tone. Most times biasing an amp up to 70% will make it sound better, but sometimes biasing a little cold makes the amp feel better.

Hope that helps.
 
parntz145":2ze539eg said:
Just wondering if anyone has tried anything different in it that sounded better than the stock ones?
What is the bias for the KT88? I called Bogner to get it and they dont go by ma. Anyone know what the bias is in ma?
Click to expand...
I put in a mix of Russian tubes and it got rid of a lot of fizz from the stock Chinese. Also seemed to tighten the amp up. I don't really care for Chinese preamp tubes though.

On another note, I bias my 101b up to 43mA. Am I going to damage something, or will tube life just be shorter? I did it because to my ears, it's where the amp sounded and felt best. Is it possible something is wrong with my amp that would cause it to sound worse when bias is set at the "correct" 70% or lower? I mean, of course it's possible, but is there something I should check for?
 
You need to know the plate voltage of your XTC. It should be around 500 to 520. With that said you want to be around 35ma. But if it sounds killer then maybe just have an extra set of tubes around in case they burn fast.
 
krueger":2x3wnr70 said:
You need to know the plate voltage of your XTC. It should be around 500 to 520. With that said you want to be around 35ma. But if it sounds killer then maybe just have an extra set of tubes around in case they burn fast.
Click to expand...
Then I guess I'll just carry around an extra set! That's where the plate voltage was, depending on where I had the bias set. I used to put it at 34 mA, but it really does sound a lot better to me when turned up higher. Feels better to play too...

Thanks!
 
Yo Cats!

Just want to bump this thread as it kinda went sideways with talking about the XTC and plate voltages and biasing and so forth... I just picked up this spankin' new TJ and I love it, but I'm still not overly stoked with the stock Chinese preamps in there - does anyone have a mapping of what the preamp sockets are for, and who's done what with what valves? I'm generally a fan of Tung-Sol, but am up for all suggestions in this department.

I am hoping to get a bit more growl out of the Uber, and less fizz... If that makes ANY sense.

Peace,
V.
 
I just installed Gold Lion KT88's and really like them.( 38ma)
They seem to be tighter and more musical.
For pre's for now
V1,V2 NOS Sovtek's( National branded) 12AX7A's
V3, V4 TungSol 12AX7
V5 Ruby 12AX7AC5
V6 Sovtek LPS.
I'm gonna try NOS Tungstram's when they arrive :thumbsup:

Got rid of the fizz and tightened'er up and also added some cut. :thumbsup:

Very happy with the change!
 
Thanks for this - what's the mapping of the preamp tubes - which one's V1 through to V6?

Peace,
V.
 
Ok I had found that but I wasn't sure if the TJ had a different layout than the other Ubers.
 
Ya, valid question for sure, but my guess is - same circuit footprint, different component mix for re-voicing.

V.

PS - what preamps you thinking about going with?? I'm wondering if Shuguang are really the best - hell, they're cheap enough, but I may do what I did to my Diezel and stick some higher grade preamps in V1 and V2 then follow out with Chinese/Shuguang.
 
I'm not sure which preamp tubes yet. I'm going to borrow a bunch from the other guitarist in my band and see if I like any of them. I'm going to start with the power amp tube swap because there are less options :lol: :LOL:
 
AusTexCap":1pj20b9t said:
I'm not sure which preamp tubes yet. I'm going to borrow a bunch from the other guitarist in my band and see if I like any of them. I'm going to start with the power amp tube swap because there are less options :lol: :LOL:
Click to expand...

Power valves? What are your options you'll be trying? I'm a stellar fan [now] of the KT88's and will stick with these, maybe just move up the food chain to Gold Lions (as I think I've mentioned 1000 times before :lol: :LOL: ). I've never tried TAD preamps, but I've got a couple for my 1st stage preamp in my VH4S. I'll see how they bode in that amp, and if solid, I'll do the same in my TJ.

Tubes are awesome things to screw with... Amazing changes can be had.

Good luck, and please keep us all posted as to what your investigations find :yes:

V.
 
i changed all of the stock chinese tubes to tung sols in every position in mine

i found it made the amp less fizzy and alot bolder sounding the low end really thumps alot more now and the response and feel of the amp is immediate and tighter....it was a noticeable differance for sure

i hate chinese tubes

imo i think bogner sent out an awesome amp with the shittiest tubes ever in it .... in a few months im gona swap out the sovtek power tubes for something else.... i was thinking penta kt88s
 
Big Rich":1yfof6zb said:
i changed all of the stock chinese tubes to tung sols in every position in mine

i found it made the amp less fizzy and alot bolder sounding the low end really thumps alot more now and the response and feel of the amp is immediate and tighter....it was a noticeable differance for sure

i hate chinese tubes

imo i think bogner sent out an awesome amp with the shittiest tubes ever in it .... in a few months im gona swap out the sovtek power tubes for something else.... i was thinking penta kt88s
Click to expand...

It's weird eh? These top-shelf boutique amps, huge price tags, everyone and their dog GASsing for 'em, and you finally get one and they're loaded with middle of the road (at best) tubes. Kinda like a sweet car with bad rubber on it. Anyway, the concept of manufacturers using Shug/Chinese due to their availability and price makes sense to me. I also know that there's a HUGE spectrum of same-model Chinese preamps - some are dead quiet with practically zero microphonics, excellent overdrive capabilities, smooth and consistent, and long living. Then, out of the same box, the next one is a dud, or the one after that squeels like a piggy. Consistency is not great, but the price is. If I could guess, I bet Bogner/Diezel and others test drive each Chinese tube to make sure they're okay - but when it comes to us replacing them, it's a crapshoot.

I see Tung Sol was mentioned up above... I am STILL a huge fan of these. You plop them in, no fuss, no muss - and they drive like tanks. No issues. Dead quiet.

V.
 
Big Rich":3dcfh9vv said:
i changed all of the stock chinese tubes to tung sols in every position in mine

i found it made the amp less fizzy and alot bolder sounding the low end really thumps alot more now and the response and feel of the amp is immediate and tighter....it was a noticeable differance for sure

i hate chinese tubes

imo i think bogner sent out an awesome amp with the shittiest tubes ever in it .... in a few months im gona swap out the sovtek power tubes for something else.... i was thinking penta kt88s
Click to expand...
You don't have issues with the Tung-Sol tubes in V3 and V5? My understanding was that those spots are too much for Russian tubes - that they bring the life down to as little as a few hours. I found this out after - of course - putting a JJ and Sovtek in V3, both of which are now dead.

For the most part, I agree with you on the all-Chinese though. I left the Chinese in V2, V3 and V5 - though I'm using Penta Chinese tubes, a company that selects the better ones - and put the Sovtek LPS in V1, V4 and V6. Bogner used to put the LPS in the Uber stock along with Chinese, and IMO this gives the amp a little more of a heavy, aggressive, full tone than the Tung Sols. But then again, there's more than one way to skin a cat!
 
i havent had any issues with it yet, ive played it extremely loud with my band about 8 times for around 6 hours each time and had no problems with anything so far

i think with the tube change it does make the amp alot heavier sounding and a bit thicker

i would like to mess around with different preamp tubes in different spots but i dont have as much experience with as many, i just know the tung sols deliver and have never dissapointed me

do you recomend any tubes in certain spots?
 
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