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What did I just buy? (TubeWorks Combo)

#21
BTW I paid $129.16 for mine in 9/2010 - The speaker frame was bent up when I got it, turns out that was done to "fix" the voicecoil rubbing (D'oh!). I have a bunch of 10" drivers on hand anyways so no big deal. As I said putting in a 16 ohm one had the advantage of getting overdrive at non-earplugs volume :) .
 
#22
teemuk said:
Uh... there are hundreds of MOSFET -based power amps still made today.
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I edited my post to clarify that I was talking about BASS amps. Also I thought when I said "analog" that I was excluding class "D" amps (which are most all MOSFET outputs) but added linear in there too in case anyone was confused. In any case I'm interested in any present production bass amps with similar output characteristics to the Tube Works one so if anyone knows of any please let us know :) . JimmyM mentioned another Ampeg already.
 
#25
MarkBass also has many MOSFET -based power amps, I think they use vertical MOSFETs.

Vertical ones have largely obsoleted the lateral ones because they are easier to manufacture for higher powers. Lateral ones have more ideal saturation characteristics and a temperature coefficincy that makes thermal tracking less important but overall these are not issues that would prevent their use in linear applications. They are just issues that force to consider different design principles than with lateral MOSFETs. Besides, vertical ones are more ideal for switching duties, and switching applications today likely make up the majority of applications for MOSFETs to begin with. So, probably just not economical enough to make something for a niche market, or at lest to sell them at the cheap prices of vertical power MOSFETs.

Today MOSFET is such a common device choice, even for linear applications, that it really isn't so worthwhile to advertise their use anymore. Just about every other company making amps will use them too so there's little exclusivity in such device choice. Many integrated power amp chips today also have MOSFET outputs. The popular TDA729x series is MOSFET -based and they are used in hundreds of self-powered PA and monitor speakers. Probably in lower power bass amps too.
 
#26
Interesting stuff guys, thanks! I should really give the RT3100 a go on one of my big 4 ohm cabs to see what it can do - I'd expect it to get about V4B loud? The Ampeg Micro-VR was really a bit much even on a largish outdoor stage with an 8x10 - I think someone measured one of those at 260w, maybe a couple db down from a "real" SVT.
 
#27
More photos :)
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#28
Vertical mosfets make poor linear amps. Many important parameters are unsuitable, things like behavior at cutoff, gate voltage steepness of the transconductance curves, bias stability, etc. What makes them a poor choice for linear applications makes them a great choice for switching!

(Edited for bad autocorrect typos)
 
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#29
Roadkill said:
I edited my post to clarify that I was talking about BASS amps. Also I thought when I said "analog" that I was excluding class "D" amps (which are most all MOSFET outputs) but added linear in there too in case anyone was confused. In any case I'm interested in any present production bass amps with similar output characteristics to the Tube Works one so if anyone knows of any please let us know :) . JimmyM mentioned another Ampeg already.
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I should say that I don't know if the 3 Pro or Micro VR have similar output characteristics just because they have MOSFET's.
 
#30
Not a whole lot of SS amps like those Tubeworks in that the transistors clip in a really musical way. I have a 3300 I really liked. It eventually burned a couple parts inside that are part of an "high frequency management network" that could've send it into oscilation. Got some good info from the nice folks here, saved that, and put the amp on my shelf of amps to mess with later, grabbed another working amp and kept gigging. Down to 2 amps now. :)

Now that the band is belly up and it'll take a while to get another one off the ground, I may have some time to work on it. I really liked it, but if the outputs are fried, they are unobtainable and it's not an amp anymore. Might be able to make the preamp useable, but those amps get a lot of character from their power section.
 
#31
Mesas Walkabout might be one that gets some tubey tone out of transistors. Ampegs 3-pro and PF do too but I don't know that any of those are like the Tubeworks in that you can musically overdrive the power section more than just a little bit.
 
#32
Agedhorse,
Is the RT-3100 speaker a standard Eminence model? I've toyed with the idea of making a matching extension cabinet for my combo, and it would be easier if I knew something about the driver. I've never bothered to disassemble it to check. Anything special about the cabinet design, or is it a straightforward box with a port in the baffle? (Oversimplification, I know...)

OP,
Enjoy your combo! Mine has served me well for about a decade.
 
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#33
abarson said:
Agedhorse,
Is the RT-3100 speaker a standard Eminence model? I've toyed with the idea of making a matching extension cabinet for my combo, and it would be easier if I knew something about the driver. I've never bothered to disassemble it to check. Anything special about the cabinet design, or is it a straightforward box with a port in the baffle? (Oversimplification, I know...)
Click to expand...

No, it was something custom (as far as we knew anyway). This was all way before GB acquired TubeWorks, we had no information on what they used on any of the older stuff. Sorry.
 
#35
I played one briefly a few months ago, and it sounded "alright" with the internal 10", but pretty good with a Carvin 1x15" hooked up as well.

I may not have gotten the best tone out of it, since I didn't know about the "everything on 10 = flat" approach.
 
#36
abarson said:
Agedhorse,
Is the RT-3100 speaker a standard Eminence model? I've toyed with the idea of making a matching extension cabinet for my combo, and it would be easier if I knew something about the driver. I've never bothered to disassemble it to check. Anything special about the cabinet design, or is it a straightforward box with a port in the baffle? (Oversimplification, I know...)

OP,
Enjoy your combo! Mine has served me well for about a decade.
Click to expand...


Being that it's not current production OEM anymore, if it is an eminence, you can email their customer service all the numbers you can find on it and they'll help you with whatever specs they may have on it, as well as recommend something from their current lineup that might blend well with it. You won't find the exact same speaker other than cannibalizing one from another old Tubeworks combo, but they'll help you the best they can. Nice folks at Eminence.
 

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