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Old 22nd April 2009, 12:49 PM   #31
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b_force,
If you can not find TUT3 you can buy mine.
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Old 22nd April 2009, 12:54 PM   #32
b_force is offline b_force  Europe
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Quote:
Originally posted by revintage
b_force,
If you can not find TUT3 you can buy mine.

That would be fine if you don't need it any more.
I'll send you a PM (e-mail)
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Old 22nd April 2009, 01:31 PM   #33
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Quote:
Originally posted by Wavebourn


The tone was exactly what I meant. However, class A is the way, but f^a^r^t^i^n^g sound (the real term of electric guitar players) may be produced by them as well (grid currents charge caps shifting bias).

This can be a problem in A/B amps as well, depends on a few factors...

BUT, why caps in that spot at all? I wouldn't.



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Old 22nd April 2009, 01:36 PM   #34
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Here's what you are going to find in practice when you try to build a guitar amp:

1. It is NOT a hi-fi amp - meaning it won't act like the hi-fi amps you've built (assuming you have).

2. Everything changes the sound.

3. You can build an exact clone of any amp you want - It will not sound the same almost no matter what you do. (There may be exceptions to the general rule - especially with solid state)

4. If you make one you really like? The next one you build to copy it will not sound the same. (unless you bought double parts or the same exact parts are still available)

5. There is no way to predict the outcome.

6. Guitar amps are predicated upon overload and distortion characteristics - not something that has been studied like reducing distortion in hi-fi amps. So, your guess is as good as anyone elses...

_-_-bear

EDIT: add: High quality OPTs are not "necessary" at all, it depends on the sound you are trying to get, and the specific requirements. Look into "Tone King" amps. Really tiny core transformers, big FAT sound.
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Old 22nd April 2009, 04:38 PM   #35
jjman is offline jjman  United States
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Quote:
Originally posted by b_force
Thank you very much, I will try to find where I can get that here in Europe.
I also have found "Valve Amplifiers" third Edition by Morgan Jones (as PDF form, if you know what I mean ).
Very well written theory, but almost 700 pages, so I think I'll buy that book to..........
I have only a few books on tube amps. My interest has been exclusive to guitar amps so far. Most of what I have learned has been from the internet and from my own builds. I found that Morgan Jones book to be almost irrelevant to guitar amps. I've (tried to) read it probably 5 times and each time I am able to digest a little more. However I still find most of it either over my head or completely unrelated to guitar amps. (I know it's not supposed to be related to guitar amps.) I'm NOT saying it's a "bad" book. It's probably fantastic and 100% relevant to hi-fi aficionados. But to me personally, as a guitar amp enthusiast, it would be the last common tube-amp book I would recommend for learning stuff related to guitar amps.
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Old 22nd April 2009, 06:04 PM   #36
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Yes, this is a great thread! Up until yesterday, my next planned guitar amp was a clone based on the Duo-Class patent. Now, I think I will build it with a "body" control to get more versatility, rather than just having a switch like a Duo-Class. I had not heard of the "body" technique until g'tube mentioned it.
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Old 23rd April 2009, 01:11 PM   #37
b_force is offline b_force  Europe
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There is something else what I think is a bit strange.

Often you see multiple channel amplifiers (eg the Laney VC50).
What they do is at a switch for bypassing or selecting a second tube to have more gain. The tubes are off course in series.
But if you at another tube, the signal will be Pi rad or 180 degrees out of phase.
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Old 23rd April 2009, 03:48 PM   #38
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Quote:
Originally posted by b_force
Often you see multiple channel amplifiers (eg the Laney VC50).
What they do is at a switch for bypassing or selecting a second tube to have more gain. The tubes are off course in series.
But if you at another tube, the signal will be Pi rad or 180 degrees out of phase.
OK, I had a look at the VC50 schematic, and if I understand you, you are questioning how the switchable section of the Clean channel can be made of 1 triode section, and the Drive channel can be made of 2 triode sections, so that when you switch between channels your signal also switches phase?

Absolute phase is irrelevant in the case of MI amplifiers (except maybe for multiple amping depending on what you are trying to achieve), and it's also mostly irrelevant in most hifi cases (single amp to single fullrange speaker).
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Old 23rd April 2009, 04:48 PM   #39
b_force is offline b_force  Europe
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M ok, but if your signal is out of phase, don't you get troubles when playing in harmony whit someone else when switching from (call it) low gain to high gain?

For example, when I'm playing with a friend the same piece of music, both signals will cancel each other out (pure theoretical, in practise you have reflections of walls and so on).

To go on with personal taste I've played and listened on quite a few amps and I always liked the sound of the Laney and of VOXes. both an open sound. VOX is really good in clean (especially with the EF86) and the Laney has a really nice open distortion sound.

Orange has it to, but is not as nice at clean sounds and is not versatile enough for me. Marshall is a bit like the Laney in distortion, but I always get the feeling that there is something wrong with those amps (the sound). Call it a bit muddy? (off course all these things are not for all amps!!)

Now I'm trying to find why I like those previous amps that I mentioned. I discovered that the chrome o zone has only a different output stage with the phase inverter completely symmetrical, while the VC50 has a 82k and 100k. There are people saying that those values are chosen because there is always a slightly unbalance. So the difference could be that the VC50 is very tight while the chrome o zone would be more a blues kind of amp?
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Old 23rd April 2009, 06:44 PM   #40
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Quote:
Originally posted by b_force
For example, when I'm playing with a friend the same piece of music, both signals will cancel each other out (pure theoretical, in practise you have reflections of walls and so on).
Why don't you try this? If you can even hear a difference, I'll be impressed.

I assure you that respecting absolute phase is not a universal design constraint in guitar amplifiers. Or maybe you've hit on a secret? Maybe the reason why the Beach Boys only used Fender equipment is that they tried just one Marshall 45 one day, but since it inverted absolute phase unlike the Fenders playing, all they heard was silence?
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