Location: Bawl'mer, MD (formerly of MS, Nawluns, Gnashville, Knocksville, Lost Angeles, Bahsten. and Philly)
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Postby David Doggett »
Michael H., I know, I know, I've drooled over your pic's of those 1-15 Boogies before. What you need four of those things for? Send me that 150 watter and I'll try it out and write you a review of it.
Speaking of tube+transistor amps, Marshall has a new 300+ watt amphead with a tube preamp and trans. power amp. Supposedly it has a clean channel so metal-heads can play clean low power chords at stadium volume levels. Who knows, this might be a good sounding steel amp in a small lightweight package.<FONT SIZE=1 COLOR="#8e236b"><p align=CENTER>[This message was edited by David Doggett on 28 October 2003 at 03:24 PM.]</p></FONT>
one thing to remember, if you are using something like the POD, let it do ALL the preamp work of your amp-- in other words, plug it into the line in jack of the peavey etc... sure you lose the tone controls on the front of your amp, but GOOD, that is why the POD has tone controls built in.. to go to the normal instrument input allows the preamp to color the sound too much.
-- back in the late '80s i was doing the rackmount preamp+ processor deal for 6 string, and everyone wanted to know why my tone when running into my Peavey Deuce was so much better than what they heard anyone else get when running their rack into a combo amp-- simple, i let the rack preamp/processor handle the preamp duties
Bobby Lee... When I first I read your comment about the difference between the solid state and tube type rectifier circuits effects on amp response I thought, "is he nuts?" But, on further contemplation perhaps there is something to it.
Have you encountered any objective data supporting your statement (as in oscilloscope results or harmonic analyzer results)? Can you hear the difference? Is the tube rectifier that guilty of B+ sag?
A week ago I'd have questioned your statement but in the last week I've been spending time trying to restore several tunes from Jimmy Day's "Steel & Strings" LP using a noise reduction/restoration program on the PC. The steel guitar waveform absolutely swamps the noise reduction module to the point of driving it crazy. The result is not nice to hear (yet..).
Is there any other instrument that is as demanding on the amplifier train as the steel guitar?
I've blown up my share of 80's and 5U4's in my time too.
Ray, tube rectified power supply sag is a huge component to an amp's sound when the amp is driven to near full power. There are many die-hard vintage guitar amp guru's who swear by the tube rectifier. When the power supply sags as it will with a tube rectifier, not only does the amp begin to compress the dynamics, but the restricted power to the amp circuit also introduces distortion harmonics of a favorable variety, if you are into the tube harmonic distortion factor. No question the tube rectifier effects the amp differently than a SS rectifier. It's an issue of linearity, compression, and distortion.
Tube rectifier "sag" is caused by the internal resistance of the tube rectifier. A GZ34 has near none and offers little sag! A 5U4GB has internal resistance and offers "sag". "Sag" is the B+ dropping as the onset of a large signal starting up (sounds little compression). As the signal develops, the B+ comes back to full rail. Little of this occurs with a GZ34.
Amps such as the Twin, Bandmaster, Vibrasonic, Vibrosonic and other use solid state diodes. Amps such as a Deluxe, Super Reverb, Vibroverb use tube rectifiers. Early Blackface amps used the GZ34 and Silverface era amps used the 5U4GB. I prefer a Weber Copper cap in my 1966 Deluxe. I get the benefit of a solid state diode and less power consumption from the main power transformer. In my Supers (I have three, 1964, 1969, 1971) I prefer the GZ34. Due to its lower internal resistance you get more B+ voltage, hence more clean power.
I just know that my little Boogie responds better with the diodes than with the tube rectifier. If you tried it you would feel the difference. At normal band volumes, it's significant.
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<font size="1"><img align=right src="http://b0b.com/Hotb0b.gif" width="96 height="96">Bobby Lee - email: quasar@b0b.com - gigs - CDs, Open Hearts
Sierra Session 12 (E9), Williams 400X (Emaj9, D6), Sierra Olympic 12 (C6add9),
Sierra Laptop 8 (D13), Fender Stringmaster (E13, A6),
Roland Handsonic, Line 6 Variax</font>
I've seen this behavior in digital logic circuit all the time. That's why each circuit package has it's own "bypass" or "decoupling" capacitor on the circuit board. Never gave any thought to it occurring in the analog world though... Stands to reason as being totally plausible.
Has anyone ever tried putting about 25,000 mfd across each side of the rectifier circuit for bypass action? You know, two capacitors about the size of a can of Budweiser each, 600 VDC rated, not readily available at your Home Depot...
