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Post by 909one on Mar 5, 2007 16:34:45 GMT -7
I've got a Maz 38 Reverb. I've been reading alot about tubes for the last couple of months and searching the forum, but I'm still abit overwhelmed - I'd like to purchase a few NOS to experiment with. My main goal is to smooth out a little bit of the Vox bite in the high end of the amp. I have heard that 5751 is a great place to start for V1 or V2. Any other suggestions for the some other tube positions? I've heard of 5751 in the PI too. Also, when it is mentioned that one tube has less gain than another, does that mean that the one with less gain will have less clean headroom and start breaking up earlier? I would imagine this also affects the overall volume of the amp too, right? So for example if you substituted a 5751 in place of a 12ax7 would the amp's apparent volume drop a bit- assuming gain between these two tubes is different enough.
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Post by myles on Mar 7, 2007 18:26:40 GMT -7
A preamp tube with less gain such as a 5751 will increase, not decrease your clean headroom.
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Post by 909one on Mar 9, 2007 10:05:41 GMT -7
Ok... I am thoroughly confused now. I think I am confused by the usage of the word 'gain' and how it relates to headroom and its point where it enters distortion..
In the guitar marketing world I think people have come to use the word 'gain' as a description for the amount distortion that an amp can put out.. For example a band like Korn uses "high gain amps".
On wikipedia gain is described as this..
"Gain is usually taken as the mean ratio of the signal output of a system to the signal input of the system. A gain of five would imply that either the voltage or power is increased by a factor of five. It has wide application in amplifiers."
So purely using the word gain to describe any electronics application does not necessarily imply more or less distortion. So in the case of using the word 'gain' to in reference to tubes I would then think that a tube which is considered to have more gain would then actually have more clean headroom.
But I guess that depends on the cicuit though... So if a tube actually less of a gain ratio then it means that it will actually be not pushing the circuit as hard, therefore resulting in less distortion. Is this correct?
Sorry for the esoterics, I just really want to understand how this stuff works. Maybe I should start reading electronics books. Anyone have any suggestions for a good place to start about building simply analog tube circuits?
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Post by kledbet on Mar 10, 2007 10:37:15 GMT -7
The 5751 will reduce the volume of your amp just a little and give you more clean headroom. From what you said I think you want a 5751 in V1. You can think of gain as volume when it comes to tubes. The 12ax7 has full volume and the 5751 has about 80% of that.
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Post by myles on Mar 10, 2007 12:17:46 GMT -7
The 5751 will reduce the volume of your amp just a little and give you more clean headroom. From what you said I think you want a 5751 in V1. You can think of gain as volume when it comes to tubes. The 12ax7 has full volume and the 5751 has about 80% of that. The volume really does not change if both tubes are at spec, it is the ratio of front end to back end distortion that changes, the front end does not go into distortion as quickly.
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