Uncle GAS Needs You: Help Design an All Tube Amp!!!

[cabcreaser]

Regarding the overdrive channel, I know jokerjkny brought up the Two Rock guitar amp earlier, but it seems that is one of the few examples of adding an overdrive option without altering the sonic integrity of the clean channel (in fact, any Dumble style one channel amp seems to achieve this).

The trick seems to be in introducing an additional gain stage that can be switched out completely, but one that does not have its own set of controls (just an additional gain and master knob). Adding an additional preamp channel seems like it might complicate matters, but just adding an additional gain stage might meet the overdrive needs but keep the design as pure as possible. I am fortunate to play extensively with a guitar player who uses a two rock and it is quite an impressive amp.

Not to ruffle any feathers (I apologize beforehand if I do), but this design needs to steer clear of anything Mesa Boogie (which does have multiple channel options). The Mesa 400+ does what it does very well, but it does not do what it seems the idea behind this amp sets out to do at all.

Check out the Two Rock (or Dumble style) overdrive idea which preserves the single channel design but adds the additional overdrive stage for a little extra grit without altering the amp's signature tone (via footswitch to boot).

In addition, in honor of Homer Simpson, perhaps designing an attached built in set of wheels with some sort of motorized device with a remote control to wheel it to gigs would be nice (or at least a strong robot that can fold up and fit in my gig bag to transport it). Or some sort of pitch/time correction effect that actually knows what I intend to play and corrects it on the spot before I mistakenly unleash it upon unsuspecting listeners (combined with some sort of electro-shock capability that punishes me for tastelessness). Or . . . . . . .

 

[luknfur]

Speak'n of. I don't suppose you (tombowlus) or anyone know of a bottle converter that's made to adapt an octal preamp tube (say 6sn7) to a 9 pin...

Guess I'll take no response as a no then.

 

[Biker4Him]

Or some sort of pitch/time correction effect that actually knows what I intend to play and corrects it on the spot before I mistakenly unleash it upon unsuspecting listeners (combined with some sort of electro-shock capability that punishes me for tastelessness). Or . . . . . . .

I don't need that... my time is perfect, the intonation on fretless is spot on, and I've never overplayed/underplayed anything.

NOBODY.. should wake me up from this dream.

 

[JacksonAmpworks]

Speak'n of. I don't suppose you (or anyone) know of a bottle converter that's made to adapt an octal preamp tube (say 6sn7) to a 9 pin. Ive' heard GT made one to go the other way at one point, but apparently it was less than successful.

You guys talking the 6s tubes got me looking into them enough to buy some but not sufficiently to have read enough beforehand to know that was not an option for the Uni. The manual said any dual triode preamp tube but left out the 9 pin part. I wasn't aware the octal preamps had the same octal power tube base. All new ground for me.

But I got some drivers and that's a start. Beep Beep m Beep Beep Yeh!

Here you go.
Link Removed

 

[luknfur]

Here you go.
Link Removed

Brad, I appreciate that and will follow up.

Glad you're getting good response in this thread. Aside from fullfilling it's intended function, it generates a variety of useful information that doesn't normally come up.

Seems like to me, for whatever reason, there's a resurgent interest in tube amps lately. Or maybe I'm just noticing it now that I'm interested.

Thanks

 

[Brian Barrett]

Brian,

How do you compare the KT90's in your new amp to KT88's as far as sound & low-end reproduction. Also, what brand are you using + how many?...

cheers,
~S~

Mine is designed to not weigh a ton and is 100 Watts of tube power with 2 KT90's and as mentioned 2 6SN7 tubes for the preamp stage. Mine is very different then what many are requesting or what other companies have built. The True-Voice Studio is designed with the same idea of the preamp’s, but including the fatness of the tube amp section. The Studio has the same features of the T-V Rack version with the Volume pre, Tonal Balance, Bright switch, Bass Boost and Amp Master volume. Its build for tube tone as Henry and Tom can both vouch that the pre’s are built around as well. These are not designed for eq color, but tube warmth and tube characteristics. Its built to be Tube Fat yet True! I don’t think anybody has built anything like this line of pre’s and amps and its been a long time coming to finally have the whole set complete. I started this venture almost 4 years ago.

Here is the proto-type Studio. The final unit won't look anything like this, but it shows the work in progress. A few people have had the satisfaction of playing through it, it’s a monster tonally and it has power for sure!

some alterations have been made since this picture was taken

 

[Fretless5verfan]

Looks great man! I might have to grab one of those for my upcomming Jazz-age band

 

[Biker4Him]

The Studio has the same features of the T-V Rack version with the Volume pre, Tonal Balance, Bright switch, Bass Boost and Amp Master volume. Its build for tube tone as Henry and Tom can both vouch that the pre’s are built around as well.

Yep, that's true!!

Interesting concept you've been working on. If it's as sweet as the TV.. it will certainly be one heckuva amp.

 

[luknfur]

Mine is designed to not weigh a ton and is 100 Watts of tube power with 2 KT90's and as mentioned 2 6SN7 tubes for the preamp stage. Mine is very different then what many are requesting or what other companies have built...[/IMG]

Boy does that look a little familiar. What are the dimensions? I know I thought the Uni was going to be this tiny little thing. More like a double Nano head than half a Bassman. It is comparatively small but not what I'd anticipated for 15W.

 

[tombowlus]

Yep, that's true!!

Interesting concept you've been working on. If it's as sweet as the TV.. it will certainly be one heckuva amp.

+1 It really is amazing how things come full circle, and we seem to have some interest in tube preamps and tube heads again!

Tom.

 

[JacksonAmpworks]

Hmmm...

May want to throw around the idea of a complimenting tube overdrive pedal in the future.

Cause if I'm paying 3k for a head....is a $200 OD pedal going to cut it for me?


...but that's for another day...

I certainly have plans for a tube OD pedal. It just simply must be done.

 

[JacksonAmpworks]

Honestly, the OD of a tube head is a deal breaker for me. Because if i'm getting a 3k tube head, i want EVERYTHING from the tubes, ya know? I don't want to have some pedal in the way of such a kickass piece of equipment. Not to mention the drive you could get out of this amp would probably sound more musical and full of tone than 99% of the pedals that are available. If anything, if you want to compete with other heads in this price range (mainly the SA200) i hear it has an incredible OD sound that is very musical and NOT "effect" like (Tom B.). And personally i'd pick an amp that can do that over one that can "just" do the clean sound well anyday.

My point is i REALLY don't want to have to buy both the ______ and the SA200

Let me ask this, do you guys want a separate channel with independant EQ controls etc, or just a gain control and a master on the one channel? The later is certainly more easily done. Keep in mind that the more extras that are included the larger the chassis becomes and the more the weight becomes an issue.

I think we can go either way, I just need clarification on what my future users will actually need.

 

[Fretless5verfan]

I certainly have plans for a tube OD pedal. It just simply must be done.

ugh...listen, just tell me everything you're gonna make for bass and the prices so i can get it out of the way .

If you can make a seriously high quality OD pedal that doesn't mess with the core of a tone significantly (and make it in black ) the OD on the amp becomes a far more minor issue. But that is a monstrous task.


Edit: just saw the post above. I was thinking the latter. If my mind isn't too blurry at the moment, it could be used (w/foostswitch) to just pop on some grit without having to turn the master down and that'd be HUGE for me!

2nd Edit: and let me answer the question you actually asked Gain and master on one channel is cool i'd think.

 

[JacksonAmpworks]

If it mucks with the design and/or the clean tone, then I agree. But, there are several reasons why I prefer a "built in" second gain stage overdrive. First off, I haven't found a footpedal overdrive that I like as well as the best overdrives I can get from an all-tube head. I realize that some of this has to do with power tube distortion, but even taking that same tube head (let's say, Eden VT-300A or Trace Elliot V8, both of which allow you to dial in an amount of preamp tube overdrive) and trying it with a good overdrive pedal (say, Fulltone Bass-Drive; leaving the head preamp set "clean"), I still strongly prefer the overdrive from the head. The only outside box that I have used which gives me the tube overdrive that I like has been the Chandler Tube Driver (rackmount) and some of its derivatives.

I hear ya on this. Yeah it might be really cool to have a separate channel on this beast. BTW - Speaking of beast, I'm really becoming attached to the Leviathan name. It's menacing and it implies HUGE which I think speaks well for a 300W amp.

Another reason to prefer built in is that it's one less thing to bring to the gig, one less thing that either eats batteries or has to be plugged in, potentially one or two less cords for me to trip over, etc.

Yeah, that's true too.

Also in the "convenience" category, I like to be able to easily set up my clean and overdriven tones to both have the same level of volume and degree of fullness, and to be able to footswitch between the two. Sometimes, I will want to do this mid-song, but more often, when we play out, I play about 45 or so tunes that I want a killer clean tone and about 5-10 where I want an overdriven tune. I'd rather be able to just use a footswitch to select the two, and for sonic reasons, I'd rather have the overdrive stage built into the head. Another use for a second preamp gain (overdrive) stage is that you would in essence have two channels that could both be "clean", with one being a more clear/refined tone (from the 6SN7), and the other having more warmth and perhaps a hint of grit (from a 12AX7 stage). So, I do think that this option would be of use to even those players who don't go for an over the top overdrive/distortion tone.

Well what if we did something like a B15N type of circuit (6SL7) for the clean sound and something more like the SVT (12AX7) for the dirty channel?

As long as we are talking wish lists for bass overdrive, a feature which I find incredibly useful (but which no one seems to offer - I have only heard this in a prototype that an EE friend and I designed) is the ability to blend the clean and overdriven tones (this is not new) and to use a variable frequency crossover to dial in just the clean frequencies below the chosen crossover point. I suppose this could work well with a fixed frequency, too (if you played around enough to confidently select one set frequency), but our unit involved a variable frequency crossover, combined with a blend knob. This allowed us to dial in a killer overdriven tone, and then bring in enough clean lows to keep it tight and full. This prototype worked like a charm, and was designed to be a second stage in a preamp design. We might try it in a foot pedal, though. I throw this out as an additional suggestion as to how to develop this second gain stage (if you go that route), but also as a suggestion for a "companion" overdrive pedal, if you decide to make one.

That's really nice! That could be really cool!

But again, if this mucks with your design goals, or stands at all in the way of the killer clean tone that you are looking for, then scrap it.

Nothing is set in stone and development is still a ways off, so now is the time to kick these ideas around.

 

[JacksonAmpworks]

The only reason i'm harping on this is because i'm sure with your skills you could do this and still keep the general tone of the amp where you want it.

Thanks for your vote of confidence. Using relays to switch channels allows the two channels to remain completely separate which of course is what we want.

 

[JacksonAmpworks]

good thoughts guys...

are there any all tube bass amps that have a footswitchable "OD" channel?

also, many small shop all tube heads lack OD, and still, IMHO, are worth it. i.e. aguilar's DB359.

gotta run, so i cant quite make my side of the rebuttal, but chalk me up for "OD isnt a necessity".

I can't tell you how many things I've purchased not because of a necessity, but because of a niceity. Niceties are important to players as they provide options. Musicians like options - this much I know.

 

[JacksonAmpworks]

Only if the volume will go to 11.

You have no idea how close I came to adding an INFINITY symbol next to my volume controls on my amps.

 

[JacksonAmpworks]

I'm sure it isn't for everyone, and to be honest, it's not a "necessity" for me, either. But it would make the amp much more attractive to me, personally. But, as is always the case, personal preferences vary.

Tom.

If you think that you could use it, then that is a good reason to implement it.

 

[JacksonAmpworks]

I like it! Of course, you could also call it "The Smalls", which would be not only a nod to Spinal Tap's ficticious bassist, Derek Smalls, but would also make for some tongue-in-cheek blatant irony.

Tom.

Man that movie was great.

 

[JacksonAmpworks]

I agree with jokerjkny on this one, the overdrive channel is not a necessity for me. However, if you can get an overdrive channel to work well I would definitely use it, but it is by no means a deal breaker for me.

Again I'll play with it and see what we come up with. It might be really great!

The 100/200/300 switch would be fantastic, but I would probably keep it at full power 99% of the time (my taste preference is definitely of the clean tube sound variety). Yet the option of reducing the power on a situational basis would provide further flexibility, I hope, without jeopardizing the initial design philosophy, which would be great.

It's really easy actually. Just disconnect the cathodes from one of the 3 pairs of KT88's and you get 200W, disconnect the cathodes from two of the 3 pairs of KT88's and you get 100W.

Regarding the name, Revolver, I was trying to think what Phil Spector, the Sixties, and Texas had in common. The only common thread I could come up with was guns. The name "William Tell" came to mind, but that might be a little too dark (assuming that is how Spector killed his wife or girlfriend or whatever she was).

Ha! I didn't get this angle!