Uberschall Rev. 2 - Retubed Preamp, But Not Quite Happy

[russellconner]

Alright, guys...I finally got around to replacing the tubes in my preamp. For a long time, I had just been putting single tubes in as some would go microphonic over the last 4 years. So yesterday, I got my tubes from thetubestore.com and switched them all out for fresh ones. For reference, I went from this:

V1 - Mesa STR 12AX7
V2 - Groove Tubes 12Ax7C
V3 - Groove Tubes 12AX7C
V4 - Groove Tubes 12AX7C
V5 - China 12AX7A (Stock from Bogner)
V6 - China 12AX7A (Stock from Bogner)

To this...

V1 - Tung Sol 12AX7
V2 - Shuguang 12AX7B
V3 - Shuguang 12AX7B
V4 - JJ/Tesla ECC803S
V5 - Shuguang 12AX7B (balanced)
V6 - Shuguang 12AX7B (balanced)

I had the master at approx. 10:00, and the distortion tone and presence controls at 12:00. It only took me about 1 minute to know that I definitely did not like the new sound.

Once the distortion channel's gain was above 12:30 or 1:00, the sound became very "congested" sounding. It was almost like power tube breakup, the top end became dull, and the bass and lower mids were bleeding into each other and sounding very muddy.

I then replaced the V1 Tung Sol with a Shuguang 12AX7B (balanced), and it cleared up quite a bit. However with the mid control at 10:00, I still have to set the treble at 2:00 or higher to get any bite. It just really seems like I lost quite of bit of clarity and top end cut with this setup...

I would appreciate any insight/suggestions you guys might have to get the great top end back in this preamp. I have noticed the noise is lower now, but I really miss the bite that the amp had before.

Initially, I thought it might be the V6 tube acting up, but the clean channel seems to sound fine. The clean channel seems to have a little more clarity in the midrange, and less noise than before.

Thanks in advance for your input,

russell

 

[steve_k]

For one thing the JJ803 is going to choke you back in V4. A Tung Sol in V1 is immediately going to change the flavor of the amp.

With what you got there, try this:

Balanced Chinese in V1
Chinese in V2
Chinese in V3
Tung Sol in V4
JJ803 in V5
Balanced Chinese in V6

Alright, guys...I finally got around to replacing the tubes in my preamp. For a long time, I had just been putting single tubes in as some would go microphonic over the last 4 years. So yesterday, I got my tubes from thetubestore.com and switched them all out for fresh ones. For reference, I went from this:

V1 - Mesa STR 12AX7
V2 - Groove Tubes 12Ax7C
V3 - Groove Tubes 12AX7C
V4 - Groove Tubes 12AX7C
V5 - China 12AX7A (Stock from Bogner)
V6 - China 12AX7A (Stock from Bogner)

To this...

V1 - Tung Sol 12AX7
V2 - Shuguang 12AX7B
V3 - Shuguang 12AX7B
V4 - JJ/Tesla ECC803S
V5 - Shuguang 12AX7B (balanced)
V6 - Shuguang 12AX7B (balanced)

I had the master at approx. 10:00, and the distortion tone and presence controls at 12:00. It only took me about 1 minute to know that I definitely did not like the new sound.

Once the distortion channel's gain was above 12:30 or 1:00, the sound became very "congested" sounding. It was almost like power tube breakup, the top end became dull, and the bass and lower mids were bleeding into each other and sounding very muddy.

I then replaced the V1 Tung Sol with a Shuguang 12AX7B (balanced), and it cleared up quite a bit. However with the mid control at 10:00, I still have to set the treble at 2:00 or higher to get any bite. It just really seems like I lost quite of bit of clarity and top end cut with this setup...

I would appreciate any insight/suggestions you guys might have to get the great top end back in this preamp. I have noticed the noise is lower now, but I really miss the bite that the amp had before.

Initially, I thought it might be the V6 tube acting up, but the clean channel seems to sound fine. I think it even has a little more clarity in the midrange, and less noise than before.

Thanks in advance for your input,

russell

 

[russellconner]

thanks, steve. i thought the V4 tube only affected the clean channel. bogner's layout diagram describes V4 this way - "Clean channel 2nd stage one triode only, 12AX7". are you saying the other half of the tube is used as a gain stage for the high gain channel?..

tonight, i thought i would put all the old clunker tubes back in and start replacing them with new one by one...instead of replacing the entire group. im hoping that i can pinpoint the tube/location that is producing the change i dont like.

For one thing the JJ803 is going to choke you back in V4. A Tung Sol in V1 is immediately going to change the flavor of the amp.

With what you got there, try this:

Balanced Chinese in V1
Chinese in V2
Chinese in V3
Tung Sol in V4
JJ803 in V5
Balanced Chinese in V6

 

[steve_k]

I may be wrong, but I think its a cathode follower in V4. Put all the horsepower you can there. I bet though, it you swap them this way, it will sound better.

Give us a report!

Steve

thanks, steve. i thought the V4 tube only affected the clean channel. bogner's layout diagram describes V4 this way - "Clean channel 2nd stage one triode only, 12AX7". are you saying the other half of the tube is used as a gain stage for the high gain channel?..

tonight, i thought i would put all the old clunker tubes back in and start replacing them with new one by one...instead of replacing the entire group. im hoping that i can pinpoint the tube/location that is producing the change i dont like.

For one thing the JJ803 is going to choke you back in V4. A Tung Sol in V1 is immediately going to change the flavor of the amp.

With what you got there, try this:

Balanced Chinese in V1
Chinese in V2
Chinese in V3
Tung Sol in V4
JJ803 in V5
Balanced Chinese in V6

 

[russellconner]

...and the report:

i tried your configuration, and then did some further swapping, and then made an observation...

your recommended setup, and some of the other ones i tried, sounded great for about 30 seconds of playing (on the high gain channel). after that, i would hear a "switch" take place in the amp. no click (like a relay) or anything, but a quick transition to a duller sound like i had kicked in an eq in the loop or something. the top end and lowest frequencies would drop off, and the lower mids would become muddy. the clean channel, however, sounded terrific without this "eq-ed" characteristic. this made me put on my engineer hat and do some troubleshooting.

heres my prevalent theory at this point: i think my power tubes are fading fast. they are the original tubes from Apr 2004, and i think the now hotter signal from the new preamp bottles is bringing out their inability to handle the hot signal level in fresh tubes. because the amp sounded great for a brief time (repeatedly) before this weird recurring transition, im assuming its the EL34s. my next step is to pick up a new set of power tubes, pray for a few minutes, and try them out with the new preamp tubes in place...but i have a couple of questions.

1. i like what im reading about the JJ E34Ls, but i wonder if its worth it to go ahead and spend almost twice as much on SED "Winged C" type tubes. Is the difference in sound/detail really so noticeable that the cost is justified? (subjective, i know)

2. when ordering matched power tubes, should i order a fifth as a spare? can it be dropped in later if one fails, or will the others drift from their baseline so much that i have to replace the set anyway?

as a side note, the tung sol sounded absolutely incredible in the V4 location. it didnt seem to have a direct effect on the high gain sounds in this location, but cleans sounded great and had less noise than ive ever had on that channel...i mean, it was silent when i stopped playing, even with the master at noon or higher.

thanks again steve for all your help,

russell

I may be wrong, but I think its a cathode follower in V4. Put all the horsepower you can there. I bet though, it you swap them this way, it will sound better.

Give us a report!

Steve

 

[steve_k]

2004???????? damn, that was a good set.

you bet dude. its all about how you hear it and what is audible to you. you get more advice on tubes that you care to hear. it basically comes down to russian or chinese. but, in all that, its the rebranding and quality control that is the key. preamp tubes are somewhat of a wide open subject, but will effect your tone much more than power tubes, in general. the main thing with power tubes is finding something that can take the pounding of an uberschall. jj's are fine in an uber, just get the e34L's. they can handle 600V. as you say, the SED's are twice as expensive. but, their dependability is great. that is the only tube I buy and all my amps, with the exception of one marshall is tubed with SED 34's. they can handle a little higher voltage. ruby HG and HG+ are great tubes right now and ruby bht power tubes are also a good choice. but, you will find more bottom end with the SED's. find a good tube provider that have good luck with.

there's a good lady on here and a fellow rt'r named laura. her website is www.valvequeen.com and she plays an uberschall. go to the site and email her and tell her what you are retubing and she will not bullshit you and will make sure tubes are culled and you get a good set. tube depot and doug's tubes are good. for jj's, eurotubes is good. but, i highly recommend laura.

you don't need a fifth tube. the tubes from laura, tube depot or doug's will have the plate current rating on it. if you need another, you can always get one same rating. but, nothing wrong with getting an extra though. a quad will stay in bias together, but may drift a couple points. its always a good idea to set bias and let the amp heat up an hour or so, or play. then go back and check it again.

steve

...and the report:

i tried your configuration, and then did some further swapping, and then made an observation...

your recommended setup, and some of the other ones i tried, sounded great for about 30 seconds of playing (on the high gain channel). after that, i would hear a "switch" take place in the amp. no click (like a relay) or anything, but a quick transition to a duller sound like i had kicked in an eq in the loop or something. the top end and lowest frequencies would drop off, and the lower mids would become muddy. the clean channel, however, sounded terrific without this "eq-ed" characteristic. this made me put on my engineer hat and do some troubleshooting.

heres my prevalent theory at this point: i think my power tubes are fading fast. they are the original tubes from Apr 2004, and i think the now hotter signal from the new preamp bottles is bringing out their inability to handle the hot signal level in fresh tubes. because the amp sounded great for a brief time (repeatedly) before this weird recurring transition, im assuming its the EL34s. my next step is to pick up a new set of power tubes, pray for a few minutes, and try them out with the new preamp tubes in place...but i have a couple of questions.

1. i like what im reading about the JJ E34Ls, but i wonder if its worth it to go ahead and spend almost twice as much on SED "Winged C" type tubes. Is the difference in sound/detail really so noticeable that the cost is justified? (subjective, i know)

2. when ordering matched power tubes, should i order a fifth as a spare? can it be dropped in later if one fails, or will the others drift from their baseline so much that i have to replace the set anyway?

as a side note, the tung sol sounded absolutely incredible in the V4 location. it didnt seem to have a direct effect on the high gain sounds in this location, but cleans sounded great and had less noise than ive ever had on that channel...i mean, it was silent when i stopped playing, even with the master at noon or higher.

thanks again steve for all your help,

russell

I may be wrong, but I think its a cathode follower in V4. Put all the horsepower you can there. I bet though, it you swap them this way, it will sound better.

Give us a report!

Steve

 

[Big Rich]

i dono if its just me but i think that when you mix up too many brands of preamp tubes in the preamp section it fucks up the way the amp breathes, and do yourself a favor and dump the JJ lol every amp i put one of those tubes in got the life sucked out of it, i hate jj preamp tubes they make every amp sound flat and feel uneven

when i had my twin jet i put all tung solls in V1-V5 and a sovtek lps in the phase inverter V6 and the amp was very open and alive sounding, it totaly improved the dynamics and enhanced the bottom end, it deff sounded more 3d also

 

[moronmountain]

I'm not 100% sure, but I thought Bogner said the JJE34L tubes were to hot for the Uber and to only use EL34 types?

 

[ttosh]

Just an FYI on the layout:

V1: Input tube for both channels, 12ax7
V2: High gain channel, 12ax7
V3: High gain channel, 12ax7
V4: Clean channel 2nd stage one triode only, Twin Jet Semi Clean 2nd and 3rd stage, 12ax7
V5: Loop, 12ax7
V6: Phase Inverter, 12ax7
V7 through V10: Power Tubes,Uberschall EL34, Twin Jet KT88

 

[just42dave]

Dump the jj

 

[russellconner]

okay...here's an update after this last weekend.

I retubed the power amp with JJ E34Ls, discovered the Tung-Sol was microphonic, and finally got the amp back to sounding great!

For you techies, here are the final configuration details:

Power Amp (V7 - V10)
Plate Voltage - 495 VDC
Bias Current - 33mA to 34mA (range of all four E34Ls)

Preamp (V1 - V6)
V1 - Chinese (Shuguang) 12AX7B
V2 - Chinese (Shuguang) 12AX7B
V3 - Chinese (Shuguang) 12AX7B, Balanced
V4 - JJ ECC803S
V5 - Chinese (Shuguang) 12AX7B, Balanced
V6 - Chinese (Shuguang) 12AX7B, Balanced

I've anly put a couple of hours on the tubes so far, so I want to break them in a bit before saying too much about the tone. the improvements so far have been dramatic regarding clarity and punch, but I know that's because the old power tubes were well past needing replacement. Thanks to everyone who helped with setting up the amp, it made my first biasing experience pretty much painless.

One thing I have noticed with the new tubes, is that the presence control on the hot channel really makes the amp sound "pushed" if it gets past 3:00 and the channel and master volumes are at noon. it sort of sounds like a little of the "brown" sound, but I'm not one to use much power tube distortion in my sounds.

-russell

 

[steve_k]

okay...here's an update after this last weekend.

I retubed the power amp with JJ E34Ls, discovered the Tung-Sol was microphonic, and finally got the amp back to sounding great!

For you techies, here are the final configuration details:

Power Amp (V7 - V10)
Plate Voltage - 495 VDC
Bias Current - 33mA to 34mA (range of all four E34Ls)

Preamp (V1 - V6)
V1 - Chinese (Shuguang) 12AX7B
V2 - Chinese (Shuguang) 12AX7B
V3 - Chinese (Shuguang) 12AX7B, Balanced
V4 - JJ ECC803S
V5 - Chinese (Shuguang) 12AX7B, Balanced
V6 - Chinese (Shuguang) 12AX7B, Balanced

I've anly put a couple of hours on the tubes so far, so I want to break them in a bit before saying too much about the tone. the improvements so far have been dramatic regarding clarity and punch, but I know that's because the old power tubes were well past needing replacement. Thanks to everyone who helped with setting up the amp, it made my first biasing experience pretty much painless.

One thing I have noticed with the new tubes, is that the presence control on the hot channel really makes the amp sound "pushed" if it gets past 3:00 and the channel and master volumes are at noon. it sort of sounds like a little of the "brown" sound, but I'm not one to use much power tube distortion in my sounds.

-russell

If you really want to piss your wife off, here's the settings for channel 2. this will rearrange all the pictures on the walls....in the next 2 rooms and upstairs:

clock settings...

Bass 2:00
Mids 8:00
Treb 3:00
Pres 2:00
Gain 1:00
Master 11:00

Main master around 10:00-11:00

 

[russellconner]

If you really want to piss your wife off, here's the settings for channel 2. this will rearrange all the pictures on the walls....in the next 2 rooms and upstairs:

clock settings...

Bass 2:00
Mids 8:00
Treb 3:00
Pres 2:00
Gain 1:00
Master 11:00

Main master around 10:00-11:00

wow, that is real close to how i normally run the hot channel! i usually have the gain at about 2:00, and the presence down between 8:00 and 10:00...i love the uber's low end with the presence dialed back.

-russell

 

[steve_k]

opposite......scoop the mids, presence and treble up.

 

[Dr. Swamp]

I have an early Revision Blue Uberschall (still have symbols for the serial). I ended up going with:

V1 - Tung-Sol
V2 - Ruby AC5 HG+
V3 - Ruby AC5 HG+
V4 - Tung-Sol
V5 - EH
V6 - Sovtek LPS

=C= EL34's in the power section. I also grabbed a Ruby AC7 HG to swap in V1 or V4, but really liked the tones I was getting with this set up right away and haven't tried yet. The tung-sol in V1 gives it a different character for sure. Got em from dougstubes. He recommended the LPS for V6.

 

[steve_k]

I have an early Revision Blue Uberschall (still have symbols for the serial). I ended up going with:

V1 - Tung-Sol
V2 - Ruby AC5 HG+
V3 - Ruby AC5 HG+
V4 - Tung-Sol
V5 - EH
V6 - Sovtek LPS

=C= EL34's in the power section. I also grabbed a Ruby AC7 HG to swap in V1 or V4, but really liked the tones I was getting with this set up right away and haven't tried yet. The tung-sol in V1 gives it a different character for sure. Got em from dougstubes. He recommended the LPS for V6.

Try one thing and see what you think and report back

Move the LPS to V2, the HG+ to V1 and the Tung Sol to V6.

See if this does anything cool for you.

Steve

 

[Death by Uberschall]

okay...here's an update after this last weekend.

I retubed the power amp with JJ E34Ls, discovered the Tung-Sol was microphonic, and finally got the amp back to sounding great!

For you techies, here are the final configuration details:

Power Amp (V7 - V10)
Plate Voltage - 495 VDC
Bias Current - 33mA to 34mA (range of all four E34Ls)

Preamp (V1 - V6)
V1 - Chinese (Shuguang) 12AX7B
V2 - Chinese (Shuguang) 12AX7B
V3 - Chinese (Shuguang) 12AX7B, Balanced
V4 - JJ ECC803S
V5 - Chinese (Shuguang) 12AX7B, Balanced
V6 - Chinese (Shuguang) 12AX7B, Balanced

I've anly put a couple of hours on the tubes so far, so I want to break them in a bit before saying too much about the tone. the improvements so far have been dramatic regarding clarity and punch, but I know that's because the old power tubes were well past needing replacement. Thanks to everyone who helped with setting up the amp, it made my first biasing experience pretty much painless.

One thing I have noticed with the new tubes, is that the presence control on the hot channel really makes the amp sound "pushed" if it gets past 3:00 and the channel and master volumes are at noon. it sort of sounds like a little of the "brown" sound, but I'm not one to use much power tube distortion in my sounds.

-russell

Try the Tung Sol RI in V1 and see how you like the amp.

 

[steve_k]

I agree. Tung Sol's are good, especially for taking the edge and shrill down a notch and smoothing it out. I am liking them more and more and haven't had a failure yet.

 

[russellconner]

I agree. Tung Sol's are good, especially for taking the edge and shrill down a notch and smoothing it out. I am liking them more and more and haven't had a failure yet.

I concur. Last Friday, the replacement for the microphonic Tung Sol arrived. As soon as I put it in, I made the same observations as you have. The top end was much smoother, and the mids seemed fuller as well. I went from moderately satisfied to very pleased, regarding the tone. its weird, though, the tung sol seems to soften the top end and somehow make the treble come on stronger at the same time. compared to having the chinese 12ax7b in V1, the treble control is set lower but still sounds like it has plenty of top end. sounds great to me though.

russell

 

[steve_k]

I agree. Tung Sol's are good, especially for taking the edge and shrill down a notch and smoothing it out. I am liking them more and more and haven't had a failure yet.

I concur. Last Friday, the replacement for the microphonic Tung Sol arrived. As soon as I put it in, I made the same observations as you have. The top end was much smoother, and the mids seemed fuller as well. I went from moderately satisfied to very pleased, regarding the tone. its weird, though, the tung sol seems to soften the top end and somehow make the treble come on stronger at the same time. compared to having the chinese 12ax7b in V1, the treble control is set lower but still sounds like it has plenty of top end. sounds great to me though.

russell

Your leading tube, the input tube in V1 is going to set the majority of the tone for the amp. You can much around with different tubes all over the place, but V1, V2 and V3 in Bogners will have the most impact. I dislike Chinese tubes in V1 as it is hard to cover up with one that follows. The TS may take it too far the other way. Which, is why I keep a drawer full of tubes. 5 minutes and two different AX7's and you can dramatically change the overall flavor of the amp.

Steve