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The Rossness

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http://www.jetcityamplification.com/retrovalves/

http://www.youtube.com/watch?v=7XRC279jhOs
 
It would be fun to try these out. At $100 per 3, that won't be happening anytime soon. Interested to hear some reviews though.
 
I wouldn't mind trying one as a phase inverter. Hardest working tube in the amp, next to the power tubes. Lifetime guarantee, huh?
 
Daryl said:
I wouldn't mind trying one as a phase inverter. Hardest working tube in the amp, next to the power tubes. Lifetime guarantee, huh?

Notice how they used the cool tube in the PI almost every time? I keep a 5751 in the PI of my RM100.
 
So...could one of our resident electronics experts please chime in and let the rest of know what these are inside and how they compare to tubes?

The Jet City rep's statement about how an amp with these replacements is still a tube amp but without tubes...is that a reasonable claim to make or does using these things eliminate any/all benefits of a tube amp (i.e. the higher voltages he was referring to)?
 
Ok, I read the whole thing;
http://www.patentstorm.us/patents/7408401/fulltext.html
What he is basically doing is using a circuit using semi-conductor devices to react as and mimic the actions of a vacuum tube. Of course, entirely possible and a great expenditure of talent, knowledge and effort. Not to mention money.
If anything, what it may not do is mimic the inconsistent properties of vacuum tubes i.e. tubes don't always sound the same and wear with age.
 
So, If I used these preamp tubes in a module, technically, would it be a solid state module? Could I possibly have a Jazz Chorus custom module with the lowest gain tubes or a Warhead with the high gain tubes??? Does this innovation make SS modules a reality?
 
These are like the Tonegrinder tube replacements. http://www.wattgrinder.com/TGDescription.htm
Where are the power tube replacements with the lifetime guarantee? That's what I want to hear about. Indestructible backup power tubes. Yeah baby.
 
kc2eeb said:
Ok, I read the whole thing;
http://www.patentstorm.us/patents/7408401/fulltext.html
What he is basically doing is using a circuit using semi-conductor devices to react as and mimic the actions of a vacuum tube. Of course, entirely possible and a great expenditure of talent, knowledge and effort. Not to mention money.
If anything, what it may not do is mimic the inconsistent properties of vacuum tubes i.e. tubes don't always sound the same and wear with age.

Thanks for your answer!

In your opinion then, there is no "loss" by using these in place of real tubes - other than the inconsistency? A semi-conductor can adequately mimic a tube on a tonal level?
 
KillTone said:
there is no "loss" by using these in place of real tubes - other than the inconsistency? A semi-conductor can adequately mimic a tube on a tonal level?

Part of me wonders what these are all about, but if they actually could mimic a tube....that guy would be a millionaire, and we wouldn't still be using tubes. Right?
 
Doug Roberts, the designer, has a history in amplifier design. He worked with Mike Soldano back in the 80's on the SLO and again on the HotMods, I believe. Below is a link to what Jet City has to say about Doug.

http://www.jetcityamplification.com/2011/01/28/doug-roberts/

I think he can make a lot of money off this, but the starting price of $100 for 3 is a bit too much. Plus, his main issue is changing musicians' perception about tubes. Guitarists are so stuck on the past and what legends used that they probably won't give these a shot. At a lower entry price, more people would try them and the mindset could potentially change.
 
First, $33.33 a piece for these is really not that much. They're made here, probably hand assembled and individually tested. Most importantly, it's an analogue device.
I have 3 old Seymour Duncan modular convertible amps from the '80s with a number of interchangeable modules. 3 of them are solid state; 1 FET based,1 opamp based, and 1 very interesting one using a MOSFET power transistor. Part of the circuit takes 400V from the plate supply.
I have the schematic as a pdf. file. It happens to sound VERY much like a tube. I am NOT saying this is the circuit that Doug Roberts is using, just that the design is a perfectly valid way to mimic the action of a vacuum tube.
I emphasize analogue because a tube's sound is NOT a collection of bits.
Digital modeling, no matter how finely done, is a bit stream that has to be converted to analogue so that we can hear it as sound. It's success in "fooling" our senses into believing it's real depends on the skill of the writer of the program.
So, would I buy these? Sure.
Would I continue to buy vacuum tubes? You betcha!
 
I used to have a SD Convertible too. Loved that amp!

I may have to give these things a try. I have been hooked on vintage tubes for a while so this would be a huge change for me.

Since they say you can use them in the PI position they must be balanced.
 
Don't get too wrapped around the axle about a "matched" PI. It's REALLY over done. I used to work in NYC in the late '60s for a Fender authorized dealer and the output tubes were never a "matched pair" let alone the phase inverter/driver tube, an 12AT7.
 
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