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Post by nlopez on Mar 7, 2008 13:43:42 GMT -7
I am new to all Tube amps. All the ones in the past I have used SS rectifiers that I never had to mess with. What does sag sound like? When does it happen? Thanks
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Post by Deleted on Mar 7, 2008 20:52:29 GMT -7
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Post by nlopez on Mar 7, 2008 21:40:38 GMT -7
Thanks!
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Post by Lefty on Mar 7, 2008 21:47:39 GMT -7
Here it is for further/easy reference.
Q:I hear a lot of people talk about tube rectifier "sag". What exactly is it supposed to sound like, and how does it happen? I'm guessing this is a good thing (tonally)?
A:The most apparent setup where sag will be noticed would be at or near full volume. A solid state diode rectifier would let through the current needed by the power tubes no problem, but the tube rectifiers have a limit to how much current they can conduct. When hitting big notes and chords at full volume, especially with overdrive happening, this is where the most current is demanded by the circuit, so with the note hit, theres this sudden stress placed on the rectifier to let through this extra current, also, at this point, the extra current demanded will lower the overall B+ voltage going to the circuit. What results is this effect that a hard note hit doesnt seem as loud as it should, and there seems to be a sort of delay feel to the note, what is happening is that as the note is picked, the rectifier stress is high, the voltage drops kind of slowly, and theres this smooth note coming through, as the guitar signal decays, the stress is lowered, and the voltage picks back up, sort of creating the effect that there is more sustain. Tube rectifier sag is basically a natural compression. Smooths out the peaks of the playing signal a bit more, and gives that nice 'spongy' attack on notes.
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Post by nlopez on Mar 8, 2008 7:40:37 GMT -7
So I guess since the amp is in my home and I won't be gigging for a while, I'll likely never hear/feel sag for a while. ( Short of getting an Airbrake.)
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Post by foxx on Mar 9, 2008 22:54:10 GMT -7
I swapped a SS rectifier in my Mazerati, and there is a difference even at lower volumes. The SS rect, is just faster and not a tube, different feel.
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Post by billyguitar on Mar 11, 2008 10:55:52 GMT -7
Sag is my favorite part of a cathode biased tube amp. It's also for those shimmering harmonics when a chord is sustained. When an amp has a lot of sag you can hear the note meow like a cat. I don't think any Zs sag that much. One exception to this is a Marshall 1987X head I used to have. It had a solid state rectifier but would meow like crazy when I had it over 1/2 way up. I guess it was the high gain being slammed into the rectifier tube and EL34s. A compressor pedal will give you almost the same feel but not the meow sound.
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