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SolidState TUBES

#82
If you ask Jonas Hellborg, he will tell you that the transformers are 100% responsible for tube tone, with the explanation that the tubes aren't supposed to impart any sound of their own to the amp. That's why his Warwick pre and power amps have big transformers, including an output transformer, which is rare in SS amps.

I don't buy it. If that were the case, how come so many people report tonal changes with different tubes? I totally buy into the transformer thing, but I don't think they do it on their own.
 
#84
Buried gate FETs - I'd completely forgotten about them!

While I agree that the transformers ARE a big factor in the tube "sound", The tubes do have a huge influence too. A guitar player who uses one of my amps often switches between 6L6GCs and EL34s - it has a bias switch. Even my damaged old ears can hear the difference between the two configurations.

Paul
 
#85
JimmyM said:
If you ask Jonas Hellborg, he will tell you that the transformers are 100% responsible for tube tone, with the explanation that the tubes aren't supposed to impart any sound of their own to the amp. That's why his Warwick pre and power amps have big transformers, including an output transformer, which is rare in SS amps.

I don't buy it. If that were the case, how come so many people report tonal changes with different tubes? I totally buy into the transformer thing, but I don't think they do it on their own.
Click to expand...

Yup and he would be somewhere between 1%-99% right. :D
 
#86
Sartori said:
Hmmm... very interesting. Is Kirkwood Labs still around?
Click to expand...

Last I spoke with Kirkwood Rough was perhaps five years ago. Even in the mid 90s, he was working somewhere in Silicon Valley and doing his music work on the side.

Actually, it was in the mid 90s that he became enamored of 12" drivers for bass, pretty much before we had production 12" cabinets. He had done some math about the response curve of the cone, and how a typical cone would smoothly cover its full frequency range without big bumps. The 12 worked out best in his calculations. I don't recall any more than that.

He did build a 212 cab for Bobby Vega of San Francisco.
 
#87
okabass said:
Yes, very interesting indeed. Can you tell us more about the circuit? It would be very cool to build and try it in real amp.
I remember seeing an SS device in the Net, which gives at least similar curves like a triode.
Click to expand...

The circuit, not surprisingly, is just a standard 12AX7 circuit. Of course it is, because the part IS a 12AX7, basically.

As for the other deal about barring inefficient amps? Of course it isn't that likely, yet........

But, when I see all the super water-saving plumbing stuff that is required by law here..... AND when I see that it rains so much here that houses 200 meters from me have been flooded 3 times in the last 12 months, I no longer have much faith in the connection of reality and laws......

Point being that tube amps are indeed very inefficient, but that the SS tubes from Kirkwood labs were less inefficient, and yet were really indistinguishable from standard types....

The point about "wear-out" is good. I know (OK KNEW, he's been gone a number of years) a local blues musician who never changed his tubes..... he wanted them soft and with no "hard edges". I heard a story about him and a tech who "fixed" his amp and put in a new tube............... he was weapon-brandishing mad....... So a tube that never wears out is not all great....

But the alternative is that you COULD MAKE ones that PERMANENTLY were in that state of soft and round sound, and you could choose to put in those, or the standard types.......
 
#88
Jerrold Tiers said:
The point about "wear-out" is good. I know (OK KNEW, he's been gone a number of years) a local blues musician who never changed his tubes..... he wanted them soft and with no "hard edges". I heard a story about him and a tech who "fixed" his amp and put in a new tube............... he was weapon-brandishing mad....... So a tube that never wears out is not all great....

But the alternative is that you COULD MAKE ones that PERMANENTLY were in that state of soft and round sound, and you could choose to put in those, or the standard types.......
Click to expand...

That seems to me to be fairly simple. Even as far as having the ability to dial in the desired amount of "deadness", similar to the voltage lag you see available on certain 9 volt power supplies to simulate the effect of a dying battery
 
#89
seamonkey said:
It's happened before.
There was a time when every telephone switching center was chalked full of 12ax7 tubes. Cost of air conditioning, inconsistency of tubes, and maintenance, and a market SS tube replacements was created. Later the whole telephone circuit redesigned around SS. For all the reasons WattGrinder points out.
Click to expand...

Wish I could find one of these rooms.
 
#90
Jerrold Tiers said:
The circuit, not surprisingly, is just a standard 12AX7 circuit. Of course it is, because the part IS a 12AX7, basically.

As for the other deal about barring inefficient amps? Of course it isn't that likely, yet........

But, when I see all the super water-saving plumbing stuff that is required by law here..... AND when I see that it rains so much here that houses 200 meters from me have been flooded 3 times in the last 12 months, I no longer have much faith in the connection of reality and laws......
Click to expand...

I think laws are more likely to come about in regards to how power is generated rather than how it's used.

Also, here, water saving plumbing is quite necessary. What most Easterners would call a drought, we call "summer."
 
#91
One feature I wonder if these SS tubes offer is a little acoustic pickup to allow for "microphony".
According to these guys it's a virtue:
Invalid Link Removed
But they haven't been able to ship any new designs yet.
I see other tube sites offering to test for microphonic tubes at an extra cost. I had assumed this was to be able to order one with a low level of microphonics, maybe instead having some is important. Could be a SS tube needs to react to a finger flick. Or need to have some resonant ringing points in their response.
 
#92
I happened across my VuDu file, complete with photos of the characteristic curve sets of a number of the VuDu SS tube devices.

I haven't searched through it to see if I have anything on the 12AX7 unit., If I find that I may post something for the general amusement, or not, if I decide it may just be free help to the comp..........
 
#93
The Kirkwood VuDu are just BiFET's wired for less gain - to simulate a tube.
US Patent 5,648,664

Now these guys are onto a truly solid state vacuum device (SSVD)
[Invalid or Expired Link Removed]
US Patent 7,397,175
Highly specialized, I don't think they'd ever make their way to consumer gear.

WattGrinder I hear has a Patent Pending. I couldn't find any details. They may be onto something totally different. I hope they, or a third party do some double blind tests. And throw in some Null Testing.
 
#95
seamonkey said:
The Kirkwood VuDu are just BiFET's wired for less gain - to simulate a tube.
US Patent 5,648,664
Click to expand...

Perhaps you should read that patent again.......

Your post implies it is some conglomeration of parts like the Pritchard patents, intended to "simulate" the tube.

Not so.

The patent appears to describe a SOLID STATE STRUCTURE, i.e. the structure of the silicon doping and geometry..... in the die itself.

So they are creating a solid state device which has the inherent characteristics of the tube. That is a very different thing, and quite different from some sort of "simulation circuit".

Don't do the easy handwaving brushoff, it is not warranted.
 
#96
Jerrold Tiers said:
The patent appears to describe a SOLID STATE STRUCTURE, i.e. the structure of the silicon doping and geometry..... in the die itself.

So they are creating a solid state device which has the inherent characteristics of the tube. That is a very different thing, and quite different from some sort of "simulation circuit".

Don't do the easy handwaving brushoff, it is not warranted.
Click to expand...

That's pretty cool. I wonder if enough has happened in the semiconductor industry since 1995 to bring the cost of fabrication into the realm of possibility.
 

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