Blue Tube 2 questions

Ray DeVoe · Post by **Ray DeVoe** » 21 Aug 2007 5:20 am

Hey electronic geeks !!!

I recently bought a Blue Tube 2 for mainly just a backup system. I already had an extra Mosvalve 500 and TC M 300 sitting around so this completed another rack amp system. As with all Tubeworks equipment, the pots needed extensive cleaning but thats done and the unit is working decently.

I have 3 questions for the electronic pro's.

Does any one know what tubes go in the Blue Tube as these are probably very old and there are no numbers on them. I dropped an email to GenzBenz support but have not heard back yet.

Is it common to heavily silicone the tubes into the sockets? I removed most of it so I could get the tubes out.

Last of all, someone asked on the forum, who installed the steel mods to these. A fellow by the name of R. Rounds wrote his name in the unit as doing the mod in 1993. Anyone know who this fellow is or who still does the mods as an answer to the above question?

Thanks
Ray DeVoe

Tim Greene · Post by **Tim Greene** » 21 Aug 2007 7:34 am

Ray A fellow member posted that the blue tube units new came with 3 sets of 2 tubes. I bought my used so Im not certain.Mine has 12ax7 tubes installed but I have tried different setups such as a 12at7 and au7 at home so im not sure if you could hear a tone difference on stage or not.Only difference I could recognize was the volume gain setting had to be raised with the lower gain tubes. The silicone was used to hold the tubes in place.With the cover off and the units front input facing you the tube on the right is the clean side and the tube on the left is the overdrive.Preamp tubes last a long time and mine had silicone holding them in place also.Not sure about the mods.

Jack Stoner · Post by **Jack Stoner** » 21 Aug 2007 7:43 am

The tubes are 12AX7's (what they came with originally).

Genz-Benz was doing the mod's, but only on the model that they produced, not the older ones from TubeWorks. I had one of the older ones and called them about it and the tech told me they wouldn't do it on the older ones as there wasn't enough documentation on the component layout. I thought that was a lame excuse for not wanting to do it, being I'm am an amp tech. They wouldn't give or sell me the info on the mod so I could do it.

Erv Niehaus · Post by **Erv Niehaus** » 21 Aug 2007 8:49 am

My Blue Tube II doesn't have the steel mod but it is still my favorite pre-amp. I retubed it a few years ago along with a Tube Works spring reverb I play through. If I'm not mistaken, I believe I used 5751 tubes. They are a lower gain tube and seemed to "sweeten" the sound somewhat.

Ray DeVoe · Post by **Ray DeVoe** » 21 Aug 2007 3:05 pm

Thanks to all who have shared their knowledge of electronics and equipment. GenzBenz also replied today with a variety of tubes numbers that could be operated in the unit. Here are their suggestions.
--------------------------------------------------
Ray,
They are of the 12AX7 family. Some suggested tubes would be the Ruby Tubes 12AX7AC5, 12AX7AC4, or 7025 SS; the JJ Electronics ECC83S (also branded as the Ruby Tubes 12AX7CZ); or the Sovtek 12AX7LPS. I hope this helps and thank you for choosing Tube Works and Genz Benz.

Scott Andres
Genz Benz / Tube Works

--------------------------------------------------

Thanks
Ray DeVoe

David Mason · Post by **David Mason** » 22 Aug 2007 7:24 am

Changing out the overdrive tube (left one) for a 12au7 put the range of useful tubiness higher on the knobs, for me. More singing and less buzzsawing. I don't remember what maker & model issue I had, it was years ago though.

Brad Sarno · Post by **Brad Sarno** » 25 Aug 2007 1:58 pm

I just got done poking around inside one of these preamps. I didn't realize that it was so full of transistors, and that the tubes aren't really operating in the real voltage range that tubes like. The plate voltages seem to be topping out at around 20v. I guess it's kind of like their famous tube distortion pedal that uses transistors for some gain staging, and simply passes thru the starved tubes to get a little of that tone quality and overdrive if you want.

I always thought these units were real tube devices, as their name would imply, but apparently not. It's kind of noisy with hum and hiss too, but not horrible. The sound is not bad, a little grainy and harsh and lacking that deep dimension that high voltage tube devices give, but really not too bad sounding. It does have a kind of lively and energetic sound like a tube amp. It's a bit solid state and edgy sounding in the treble, but more tubey than an all transistor preamp. I bet for steel players who like a good amount of bite and cut, it's probably a pretty decent device. But for big, warm, lush and detailed, I'd say actual tube preamps have it beat pretty good. IMHO

One bonus is that since the tubes aren't actually operating at real tube voltages, they should last a long time.

Brad

Jack Stoner · Post by **Jack Stoner** » 26 Aug 2007 3:06 am

Brad, if you look at the PC board you will see that the power supply components (and AC voltage) are adjacent to the tone controls for the "clean" channel. If you raise the bass control up over about half you start to get hum. I had one of the preamps for a while in my rack system (one of the original models) and I talked to the Genz Benz tech about that and he acknowledged that it was a known problem. I had considered "remodeling" the power supply and moving it off of the PC board and getting the AC away from the tone controls and circuitry but wound up selling it.

According to my EE friend, Blake Hawkins, the low voltage B+ design has been around for quite a while and used in a lot of equipment. It gives it a little bit of a tube sound (and they can say it's tube), but it is mostly solid state.

Erv Niehaus · Post by **Erv Niehaus** » 26 Aug 2007 5:55 am

This preamp is very versatile when it comes to hooking up effects also. It has a lot of different controls on the back side.
Tube Works also has a spring reverb unit that is hard to beat. It is a stereo unit and the channels can be combined if you REALLY want reverb!

Ray DeVoe · Post by **Ray DeVoe** » 26 Aug 2007 7:33 am

I'm sure that it's pretty obvious that Brad has the pre-amp that I bought off the Forum.

It was working fine after I cleaned the pots but Brad contacted me as he had not viewed one of these yet and he offered to professionaly clean the amp up and check the tubes at "no cost." That's hard to turn down.

Brad asked me to send the pre-amp to his shop so that he could see what the pre-amp and mod was all about. It's definately not a "Revelation" but it could be considered a fair " tube pre-amp".

The sound of the modifed Blue Tube was fairly decent when set up with my rack combination. It was a bit bright and only had about so many tone options but these were in a decent range. It's hard for me to fairly state how good the actual preamp stand alone sound is, as when I tested the unit, it was combined with the best off all equipment. But as we all know, the sound is the combination of all components as well as the man behind the guitar.

My setup consisted of a 1967 Emmons P. P. with Lawrence pickups through the Blue Tube, TC Electronics M 300, Mosvalve 500 and nicely built Rick Johnson cabinets with 1501-4 Black Widow speakers. The bright harshness of the preamp was able to be cut back with the presence controls on the Mosvalve.

Even though it could not match up to the sound quality and versatility of the same rack setup with my Revelation installed in its place, the Blue Tube 2 was nothing to be ashamed of. The sound was warmer and a lot more tube like than any S.S. amp that I have owned.

Some of the nicer features of this preamp is the dual line out levels. It can be used to connect to a standard power amp or it also has a reduced level line out so that it could be put in front of a regular amp's input for possibly warming the tone a bit.

The bottom line is that it is a 2 channel preamp with stacking features that was designed around guitar players. The mod has helped bring the unit into a more user friendly range for steel guitar amplification. I would not have a problem using this amp at all as a backup in the event my main rig had a tube or electronic failure. It's a keeper as far as I'm concerned.

I want to thank Brad and all for their shared experience and knowledge as to where this unit fits in as to steel applications. This forum, the players and the electronic geeks out here have vastly advanced the steel guitar community as a whole.

Thanks to all.

Ray DeVoe

Jerry Overstreet · Post by **Jerry Overstreet** » 26 Aug 2007 9:40 am

Ray, let me just add this. As Erv has pointed out and you have agreed, the BTII is a very versatile unit. Especially it you play another instrument like 6 string or slide of some kind where you would like a little edge or grit.

I have had one of these just about since they became available.

There's no denying the malady that is the noisy pots on these, but it's not an insurmountable problem.

As to your observation re: the bright color of the unit, that may be typical of this unit alone, but I would submit this: If you are willing to and can find the Real Tube Reverb RT921 unit to add to your Mosvalve rig, you will find this is the heart of the Tubeworks system. It will warm, open up, and mellow out your tone even to the point you need to to careful of too heavy a sound. It adds 2 more 12ax7a's to the sound along with 2 complete eq's for your stereo sides. I feel the Tubeworks rig is incomplete without this unit.

I speak from experience using this complete system with the MV500 for some 15 or so years. It's far and away the best sounding rig I ever had. The sound is open and bigger than I could ever have imagined. Very unlike the run of the mill SS units and having more of a tubular character. JMO.

Well, I nearly forgot the original question: I tried several different pre tubes in my Blue Tube II without gaining anything. My final analysis was that BK Butler had it right. I swapped out some old sylvanias and some Groove Tube "R" units. I found the sylvanias too weak and encountered an unacceptable hum with the Groove Tubes although the dirty channel may have had slightly more umph.

Aside from this, with the RT921 switched off, I get absolutely no hum from my BTII or the system. With it on, there is a slightly audible noise, but you'd never hear it in a live situation. For recording, you'd reduce the overall volume anyhow and I wouldn't see it as a problem.

Jack Stoner · Post by **Jack Stoner** » 26 Aug 2007 11:52 am

The one I had (for about 6 months) was connected to a MosValve 500 power amp. Being an amp tech I'm probably a lot more critical of any electronic component than many non-tech's.

But, as acknowledged by Genz-Benz, the physical layout of the components and the poor choice of unshielded AC power so close to the EQ controls is a real issue.

As these were mostly used by Rock Guitarists they primarily used channel 1 so the channel 2 "hum issue" was never a problem and if they used channel 2 the Low control was probably never set to the point the hum was heard.

Jerry Overstreet · Post by **Jerry Overstreet** » 26 Aug 2007 1:50 pm

Jack, I'm not disputing the technical info you present. I'm not sure how they compare, but the original Blue Tube II is the design of BK Butler not Genz Benz, the present owner of the product whose preamp issue was the 9002 I think?

If they indeed acknowledge a problem with a high noise floor on the original unit, I accept the info for what it is.

All I'm saying is that it hasn't been much of an issue for me on either the red or green channel, and the very slight hum in the system goes away with the 921 switched out, therefore I surmised that the major share of any noise was generated by that unit or perhaps the combination of the 2. Could be I just have a tin ear or am largely deaf from playing with ungodly loud bands all these years

Jack Stoner · Post by **Jack Stoner** » 26 Aug 2007 2:11 pm

I know the Genz Benz produced model was electronically and component layout basically the same as the original model. They did document where all the components were on the circuit board, something that was not documented on the Butler produced models.

I talked at length with their techs about the hum problem and each one I talked to acknowledged the same thing about the power supply components too close to the EQ circuit and nothing short of a complete re-design of the component layout/placement would fix the problem.

The hum was evident in mine, if I got the low control over half way, with just the preamp and the MosValve 500 power amp hooked together. No other components in the rack and no other devices connected to the effects loop.

The amount of hum probably would not have been noticed on a stage, unless it was miked. But, it would be noticed in a studio and again because I am a finicky tech I noticed it and knew it was there.

I've heard guys that have noisy effects, bad cords, ground loop hums and whatever and they just ignore it and play like nothing is wrong and never get the problems corrected. I would never put up with stuff like that, whether at home or on stage.

Jerry Overstreet · Post by **Jerry Overstreet** » 26 Aug 2007 2:28 pm

I still contend that it isn't much of an issue with my modded unit.

I can't help wondering that if GB acknowledged the problem and knew the cause, why didn't they fix the damn thing when they acquired the company and put out their own version? How much of a problem and expense would it be to move the power supply away from the eq section:?: oh yeah, mighta cost them a buck or 2 ... and for FWIW, I'm very picky about my sound and would never allow anything noticeably noisy in my rig.

BTW, I have a couple of CD's recorded by Herby Wallace using this exact rig and I don't hear any hum there.

Sorry Ray, I won't bore the folks and further dilute your thread with further comments on this topic. I hope you got the information you were seeking and that the unit works out well for you. Peace be with you all.

Brad Sarno · Post by **Brad Sarno** » 26 Aug 2007 4:42 pm

From peeking inside the thing, it appears that the main aspect of the mod was probably the conversion of the heater supply from AC to DC. This can definitely reduce hum in any tube circuit. The modded one I've got here is still noisy, but not offensively so. But that's comparing its noise level to levels found in "real" tube preamps that cost a whole lot more money, so maybe the comparison isn't really fair. I'm assuming that the pre-modded version of this preamp was even noisier.

BK Butler had perhaps their greatest success with the Tube Driver distortion pedal which is still highly regarded in certain circles. David Gilmour is a famous example of this pedal at work. It was also based on a solid state circuit with a single starved voltage tube in it where the actual overdrive took place. These preamps are kind of built more with that guitar pedal kind of mentality, cheaper parts, easy build, low voltage, affordable, etc. In all fairness it's a decent preamp that, as Ray said, is warmer than an entirely transistor preamp. The EQ point are in that familiar Fender style too, so tone and voicing is easy to dial in. For the money, these really seem to be a pretty good deal.

"It dont' mean a thing if it ain't got that swing."

Brad

Jack Stoner · Post by **Jack Stoner** » 27 Aug 2007 2:29 am

The unit I had wasn't noisy and if it wasn't for the hum in the 2nd channel (which is what is used for steel) I would probably still have it (and now trying to sell it as I'm selling off my rack system components).

It would have taken major PC board layout modificaton, internal component placement, etc to isolate the power supply (actually a complete redesign, not a minor change). The first basic rule of design and layout was violated when you have AC power and audio in the same chassis (Brad can chime in on this).

Ray DeVoe · Post by **Ray DeVoe** » 27 Aug 2007 3:33 am

I certainly ended up with a lot of different thoughts and opinions as to this unit.
Thanks to all.

I recently put in a plug for Tim Bridges when he was selling off a Tubeworks Mosvalve 500 poweramp. I stated that these are getting rare. The most I have observed one selling for was $375 on Ebay. Take a look at the one on EBAY now. I'm glad I have several of these as I wouldnt be out there competing for one at this price.

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... :IT&ih=005

Thanks again to everyone who replied on my original topic.
Ray DeVoe

Erv Niehaus · Post by **Erv Niehaus** » 27 Aug 2007 6:38 am

I use the Blue Tube II and the 921 Spring Reverb by Tube Works. I had some hum but eliminated it by moving my power amp to a separate rack case.
This eliminated 99% of the hum. I took the advise of a fellow Forumite and bought a 290 VHT tube amp and bought a 3 door rack case from Fred Justice to put it in. Besides eliminating the hum, it lightened up the case with my other "stuff".

Ray DeVoe · Post by **Ray DeVoe** » 27 Aug 2007 6:47 am

HI Erv.

I did experience the same problem when I tried out the Blue Tube 2 before shipping it out to Brad.

I had an old 4 space rack sitting around so I mounted the Mosvalve 500 in the top 2 slots and then the Blue Tube and finally the TC M 300.

I had plenty of noise and hum. I just ended up swapping the position of the TC unit and the Blue tube and it eliminated just about all of it. It does not pay to mount the Blue Tube next to the power amp.

Ray

Bob Snelgrove · Post by **Bob Snelgrove** » 8 Sep 2007 7:14 am

Anyone have pictures of the BT II? I searched the net with no luck!

thx

bob

Kevin Mincke · Post by **Kevin Mincke** » 8 Sep 2007 11:11 am

Bob Snelgrove · Post by **Bob Snelgrove** » 8 Sep 2007 11:21 am

Kevin Mincke wrote:

Thanks, Kevin

What EQ is on the clean channel?

thx

bob

Mike Wheeler · Post by **Mike Wheeler** » 8 Sep 2007 2:38 pm

Bob, here's a link to the User Manual. It describes all the controls.

BT2 Manual

Mike Wheeler · Post by **Mike Wheeler** » 8 Sep 2007 2:40 pm

oops, double post.

The Steel Guitar Forum

Blue Tube 2 questions

Blue Tube 2 questions

Thanks

Blue Tube

Blue Tube 2

Hum