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I was searching through an online marketplace when I came across this Tube amp in the pictures.

 

Very tempted to purchase it.....clean it up and then determine if I keep it, or try and sell it.

 

Opinions?  Where is Tom Pappano when you need him? LOL

 

It is a VTL 120/50

 

IT's a little Dusty

 

 

What it looks like in pristine condition with the cover off:

 

Not sure what a respectable price would be

 

Jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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I feel 50 years younger just looking at the pictures.

John Samperi

Ampertronics Pty. Ltd.

https://www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Eight 807s, that'll wake up the neighbors.

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Bah, if it doesn't say 'Quad II' on it it's not a *proper* valve amp cheeky

 

Neil (which sort of distortion does sir prefer?)

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Is that authentic dust or reproduction dust?

If it works, does it really need any cleaning or restoration?

 

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Was there a picture of the wiring ? Especially the coupling capacitors.

I see a trace of rust on the transformer ironwork.

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While normally I would take the position that obsolete technology should be allowed a natural death, I must allow that an exception might be made for tube-based audio amps.  There are a reasonable number of civilized people who believe that tube-based audio amps actually "sound better" than silicon transistor based technology.  Something about the correlation between the non-linearity of the ear vs. the non-linearity of the vacuum tube gain curve.

 

The tube-amp will continue to exist as long as these tube-tech affectionados have lots of money.  Lots.  A quote of this VTL 120/50 restored was $1300 in 2018.

 

For the rest of us who live in the real world,  here's a 50-Watt modern amplifier chip that sells for a few dollars.  TDA7492MV    It has maybe five or ten surrounding components instead of a hundred.

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Does anybody else watch the Mr Carlson's Lab channel on youtube ? Frequently has valve/tube-based rescues and rebuilds. https://www.youtube.com/user/MrC...

 

(For the Americans here, which part of the US is his accent from ?)

 

The only valve amp I have is in my Leslie speaker. A very loud 40 watts.

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obdevel wrote:
(For the Americans here, which part of the US is his accent from ?)

Sounds pretty Generic American (a.k.a. TV & Radio American, the standard broadcast accent), but I did catch some northern midwest in his pronunciation of "about" and "output", so maybe up around Minnesota?

Last Edited: Sat. Dec 5, 2020 - 04:38 PM
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kk6gm wrote:

obdevel wrote:
(For the Americans here, which part of the US is his accent from ?)

Sounds pretty Generic American (a.k.a. TV & Radio American, the standard broadcast accent), but I did catch some northern midwest in his pronunciation of "about" and "output, so maybe up around Minnesota?

 

Those were precisely the sounds that caught my attention. Thanks.

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In the Fond Memories category, I built my first amplifier (tube) when I was 12.  It was a guitar amplifier for an electric guitar that my mom brought home one day after she bought it for $20 on some closeout.  I used parts out of old TVs that family members were happy to dump off at our house.  Tube was a plate cap sweep tube, maybe a 6BQ6 or 6DQ6.  Amplifier was built on a board with all the HV points fully accessible for the errant hand.  And the sucker worked.  Gave lots of volume into an old PA speaker that my dad had.  Looking back, I'm not sure how I got so much volume without using a preamp tube for the guitar pickup, but then, sweep tubes have a good amount of gain.

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Simonetta wrote:
There are a reasonable number of civilized people who believe that tube-based audio amps actually "sound better" than silicon transistor based technology. 

I am one of them.  Especially when running in Class A mode.  Although many discrete transistor models running Class A are excellent as well. 

 

Discrete Transistor Class AB which have been the standard for many years until Amplifier 'modules' started showing up do an excellent job as well when made properly.

 

Simonetta wrote:
The tube-amp will continue to exist as long as these tube-tech affectionados have lots of money.  Lots.

Yes and no on the LOTS of money part.  It all depends on what you consider LOTS, and the product you are buying.  If you look on Bangood, they are selling Tube amp kits for not very much.  Amazon as well.  I have been tempted to buy a kit and build it to see how they fare against the big boys...hmmmm...cheeky

 

Simonetta wrote:
A quote of this VTL 120/50 restored was $1300 in 2018.

Thats accurate.  Considering when it was new back in the 1990's it retailed at close to $3000 the depreciation is not that bad.  I am repairing/restoring an ACOUSTIC360/362 set that in so-so condition is fetching 4 figures.

 

I will concede that this is all based on the purchasers limits of what they will pay for something, like in any other item.

 

Simonetta wrote:
For the rest of us who live in the real world,  here's a 50-Watt modern amplifier chip that sells for a few dollars.  TDA7492MV    It has maybe five or ten surrounding components instead of a hundred.

Fair enough, and for the S*** 'music' being created today where the 'instruments' are digital drum pads, keyboards, and guitars from one video I have seen are perfect for those amplifiers. 

 

I use select set of 'reference' songs when I test out audio systems.  I was talking with another Freak on the phone last night(yes, and ACTUAL telephone conversation!!) regarding test songs and he agreed 'Comfortably Numb' by Pink Floyd is a fantastic choice.  I used that song in analog format once to compare a Tube amp, Class AB, and Class D amp side by side with the same Source, Same Speaker for each amplifier.  All three were 100 Watt models and the Class D did not produce the same 'warmth' that the other two did.  Especially in the bass guitar, and during the lead guitar solos.  the sound was 'rigid'.  To each his own.

 

Simonetta wrote:
While normally I would take the position that obsolete technology should be allowed a natural death, I must allow that an exception might be made for tube-based audio amps. 

There might be hope for you yet.....smiley

Are Tube amps an efficient product to build?  Nope.

Are tube amps an efficient amp to operate? Nope.

Are tube amplifiers efficient on your pocket book?  NOPE.

Are tube amplifiers easy to design and build? NOPE.

Are tube amplifiers an interesting hobby? YEP!

 

One could replace Tube Amps with 'Classic Cars'

One could replace Tube Amps with 'R/C Airplanes'

One could replace Tube Amps with just about  ANYTHING in the above 5 questions and the answers would/could be the same. It's all based on what you enjoy doing during your relaxation opportunities

 

Cheers,

Jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

Last Edited: Sat. Dec 5, 2020 - 05:22 PM
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For years, I have searched for audio measuring instruments that can measure 'warmth', 'rigidity', 'rhythm', 'pace' and the other subjective terms one finds in audiophool audiophile discussions. So far I have been unsuccesful.

 

I refer m'learned colleagues to my earlier comment: what sort of distortion does sir prefer?

 

At the risk of preaching the obvious to engineers: a valve amplifier will *always* have worse distortion of one sort or another than a competently designed silicon design, mostly because they operate as a rule at low gain and with little or no negative feedback. The non-linearities in a vacuum field effect device will always find their way through to the output; one reason valve amps are considered to sound 'warmer' than transistor amps is that as they are over-driven, they don't clip in the same hard way; instead of third harmonic distortion you get second harmonic. A FET amplifier in many ways can offer the same sort of overload handling but with a more linear response at sensible levels, and can manage without that huge chunk of iron in the output chain required to match the high-voltage low-current valve output to a low-impedance loudspeaker.

 

But what do I know? I was calculating gm curves for valves in the BBC in the seventies, and spent twenty or thirty years designing audio studios for them... and believe me we were not impressed with the likes of the 'audition rooms' of Ken Kessler and his cohorts.

 

Don't get me wrong: I like the sound of valve amps; the fore-mentioned Quad II in particular. But they're not 'good' in the sense of there is no difference between the input and a padded-down version of the output; it's just that the distortion that is there is easy on the ear.

 

Neil (I like steam engines too, but I wouldn't put one in an aeroplane!)

Last Edited: Sun. Dec 6, 2020 - 07:40 AM
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Friend of mine many (many!) years ago had a business in building transistor amplifiers that "sounded like" tube amplifiers.  Long after that biz was done and gone, he admitted his 'secret sauce' was controlling the peak rolloff : driving a transistor to the rail (or current limit) gets you a sharp cutoff (and (nasty) high-frequency overtones) while driving a tube to the rail rolled off much more smoothly.  His solution was a little circuit that made the transistors roll off smoothly - like tubes.

 

Apparently it worked, for awhile.  S.

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barnacle wrote:
Neil (I like steam engines too, but I wouldn't put one in an aeroplane!)

 

Strictly OT, but there were steam-powered aircraft long before the Wright Brothers.  There were people taking steam engines up in balloons and puttering around Paris for many years before fixed-wing powered aircraft took to the air.  Santos-Dumont was one of the more famous ones who later moved into heavier-than-air operation.

 

And oddly enough, just the other day it struck me that, as far as I know, I could get my name into the record books by being the first person to successfully build and fly a steam-powered helicopter...  cool  S.

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barnacle wrote:
Neil (I like steam engines too, but I wouldn't put one in an aeroplane!)

Me neither. smiley

 

I was not mentioning anything about distortion at clipping, I was referring to the operation within non-clipping limits.

 

 

barnacle wrote:
But what do I know?

Obviously quite a bit.  Excellent information, as always.

 

Jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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barnacle wrote:
vacuum field effect device

Tubes: Luckily, They’re Still Around | Electronic Design

by Lou Frenzel

JUN 08, 2020

...

 

Sounding Off: Tube or Solid-State Amp?

...

 

The inexpensive solid-state amps at the 10- to 20-W level sell for $100 to $200. A 100-W tube amp can sell for several thousand dollars depending on the accessories.

 

...

 

By the Book

...

These are vacuum electron devices (VEDs). 

...

tube pre-amp, class-D 60W out (bass guitar)

DEMOBASSAMP60W1270TOBO1 Demo Board - Infineon Technologies | Mouser

 

"Dare to be naïve." - Buckminster Fuller

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barnacle wrote:
So far I have been unacceptable.
That gets lost in translation.

Ross McKenzie ValuSoft Melbourne Australia

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Unsuccessful. My bad, now corrected.

 

<pedant> A powered balloon in an aircraft, but it is not an aeroplane! It lacks wings... though I'm not sure where that lifting body almost-lighter-than-air transporter fits in :) </pedant>

 

Neil

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I was carefully specific.

 

More on topic, though, I think the major (and possibly only detectable) sonic difference between tube amps and transistor amps is in the clipping, or approaching clipping, range of the envelope.  Below there, they're linear - and pretty darn linear - it's only when they reach the limits that they start to sound different.  Even quiet music can have moments where the amp has to drive hard to suddenly throw in a certain note.  S.

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Simonetta wrote:
There are a reasonable number of civilized people who believe that tube-based audio amps actually "sound better" than silicon transistor based technology.

Aside from all the other well-rehearsed arguments, I wonder how much of this comes down to comparing top-of-the range, really-well-designed/crafted, niche valve amps with run-of-the mill, mass-market semiconductor products ?

 

Just a thought.

 

Jim's point about the type of music you listen to is also a good one.

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Last Edited: Sun. Dec 20, 2020 - 01:03 PM
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obdevel wrote:

Does anybody else watch the Mr Carlson's Lab channel on youtube ? Frequently has valve/tube-based rescues and rebuilds. https://www.youtube.com/user/MrC...

 

(For the Americans here, which part of the US is his accent from ?)

 

The only valve amp I have is in my Leslie speaker. A very loud 40 watts.

 

I always thought Mr. Carlson was pretty cool... until he started twisting off SMT electrolytic caps with a pair of pliers. Sure, do that kind of thing in private, but to post a video of it???  For shame.

 

 

Gentlemen may prefer Blondes, but Real Men prefer Redheads!