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Valvestate - tube magic or in my head?

Started by joecool85, January 20, 2011, 07:22:20 PM

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joecool85

This is in reference to my new to me Vox AD50VT.

I haven't ever owned a tube amp before (except for the 12v Sopht amp I built while in college) and wow, my Vox sounds awesome.  It just has a great sound to it.  Very clean, but warm.  And with the overdrive on it seems to be more mellow than my solid state gear.  That said, I've yet to get a good metal sound out of it even with an overdrive in front of it and in the highest gain setting.  I miss my Black Coffee Metal Pedal...

Back on topic though, is it just me, or is the 12AX7 really helping make the amp sound great?  Or maybe it's just that Vox makes a good sounding amp?  Whatever it is, it makes me want to play it ALL the time.  This is probably the most I've played guitar (in one sitting) since I started playing 8 years ago.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

J M Fahey

Rather than the 12AX7 which for all I know might even be cosmetic or a marketing trick, these guys are not VOX at all but Korg; they do have a long and distinguished career making good sounds, lately digital emulation of everything.
As I see it, they sound good because of that; a VOX label plus the mention of the word "tube" definitely does not hurt sales either.
Just my two cents.

joecool85

Quote from: J M Fahey on January 21, 2011, 04:13:10 AM
Rather than the 12AX7 which for all I know might even be cosmetic or a marketing trick, these guys are not VOX at all but Korg; they do have a long and distinguished career making good sounds, lately digital emulation of everything.
As I see it, they sound good because of that; a VOX label plus the mention of the word "tube" definitely does not hurt sales either.
Just my two cents.

I know that Vox got bought out by Korg (sometime in the late 90's right?), but this is as "Vox" as it gets unless you buy an old one.  As for the tube, it does do something because I've read that changing it out can get you a tiny bit more clean headroom (not much, but just enough to be noticeable).  Most people don't recommend changing it since it is such a small difference.

It does make me want to try out an old Vox though, specifically one of the legendary AC30 or AC15 models.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

J M Fahey

#3
Go for it  :tu:
I suggest you don't build the "full" AC30, which has 3 channels yet the "good" one is the bright one, the one which provide that chimey jangly tone .
The others are somewhat "raw" and dull.
Check the Hoffman site , they offer a tagboard to build it, in a simplified form, only two channels, they explain the (very good) reasons for not including the Tremolo channel.
I checked and now they split into http://www.hoffmanamps.com/MyStore/perlshop.cgi?action=template&thispage=BoardBuilding&ORDER_ID=242708007 and http://www.el34world.com/boardmaker/oldboardkitpage.htm ; browse both , they are fascinating sites, chock full of surprises.



Good luck.

teemuk

QuoteBack on topic though, is it just me, or is the 12AX7 really helping make the amp sound great?
The tube is a part in the rather clever architecture of the power amp, so yes. But all in all it's not the tube alone, rather than a sum of many, many things. What really makes the amp sound great is the entire design, not just a single part of it.

QuoteOr maybe it's just that Vox makes a good sounding amp?
Well... yes... Isn't that kinda like the entire point?
There are many, many other amps with an 12AX7 tube inside them and they don't all sound the same. The design counts, these guys made a good sounding one.

If you want to know what that tube does you can just download my book (you find a link from this forum's stickies) and read about Korg's "Valve Reactor" circuitry. It's a quite tech-heavy explanation, though.

joecool85

Quote from: teemuk on January 21, 2011, 10:19:02 AM
If you want to know what that tube does you can just download my book (you find a link from this forum's stickies) and read about Korg's "Valve Reactor" circuitry. It's a quite tech-heavy explanation, though.

I have your book (actually, I'm the one hosting the PDF file remember?), I just didn't remember reading that bit since at the time I wasn't interested in it.  I may have to take another look at it.

Also, Juan, I wasn't planning on building an AC30 but rather trying one out in a Music store etc...but now I'm curious about building one.  Definitely a project for "down the road" since I have no time or money for it right now though.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

J M Fahey

The "full" AC30 is too much.
Besides, the "good" channel is only one, so by building a simplified amp things start to become reasonable.
I'd say: try to grab any old, used tube amp for cheap; best if nonworking, you want it only for the transformes, consider chassis, sockets and a few other usable parts as a gift.
You may even build a 15W version with only 2 6BQ5/EL84.
That broadens the range of useful derelicts.
Search EBay, Craigslist, Salvation Army, etc.
That leaves you with making the board yourself with a piece of non-copperclad epoxy material and a few hollow nickel rivets (I prefer them to turrets).
Parts are parts, you'll have to buy them for any project you build.
You may even re-use some from the old amp, specially polyester caps and such.
Replace all electrolytics.
The Hoffmann layout is very clean and logic, mounting that amplifier is a bit like "painting by the numbers", you just do it and in the end you have a usable product.
Good project for long winter nights.
If you want something more documented, AX84 projects are *very* good.

Jack1962

Well this is just my opinion , I personally don't hear a tube tone coming from these amps , I repair tons of these every year , and the people that own them love them, I own a AVT150 myself I modded the output to a tube output(4-EL34's) it makes a good backup amp.  However, if you like the tone the that's all that really counts  :tu:

joecool85

Quote from: Jack1962 on April 11, 2011, 12:28:14 PM
Well this is just my opinion , I personally don't hear a tube tone coming from these amps , I repair tons of these every year , and the people that own them love them, I own a AVT150 myself I modded the output to a tube output(4-EL34's) it makes a good backup amp.  However, if you like the tone the that's all that really counts  :tu:

I actually just sold it to my brother.  I do like the tone and it's much different from most solid states I've played, but I don't have a whole lot of experience on tube amps so I guess I can't truly say if it is a good "tube" sound or not.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

phatt

Joe,
The hardest part to capture is the power stage of an all Valve amp.
As you would know by all the comments on here, LOL Not easy to do via SS devices.
The Valtronix stuff claims great things and I was really  hoping that all the blab be true but after spending a whole afternoon in a shop trying out all the different models,,,, well lets just say I ended up plying a Deville before I left the shop as that was more pleasing to use.

And normally I absolutly HATE Deville's :lmao:

KMG's stunning circuit would probably be far more realisitc that the Valvetrontricx gear. He certainly comes very close to pulling off the holy grail.

Quite frankly I doubt any SS Amp which tries to imitate a Valve circuit will ever succeed unless it uses transformers.
OTR's are like a wheel *almost impossible to superceed*

Believe me I was so interested in the Korg ad stuff I downloaded all the patents and read up on how they worked,,,,sadly in the real world they where a joke IMO.

It comes down to what *Jack* said,,, the kids love em,, so go figure.
Phil.