Dave da Dude

Myles, A quick and easy one for you. I'm just confused. I've got a '93 Randall Tube Pro II amplifier that takes either (2) 6L6's or (2) EL34 power tubes (switchable bias). I've been under the impression that it is a "50" Watt amplifier. I was at the Ampage site and saw their reference section on tubes, so I took a look. They show the 6L6 in an AB1 amp to be 26.5 (or 19) watts for two (2) tubes and the EL34 in an AB1 amp to be 40 watts for two (2) tubes. Either I was misinformed about my amp's power, or if the data is for one (1) tube it would make my amp a 53 W (6L6's, or 38 W) or 80 W (EL34's) Is this info at Amapage a typo? Am I wrong about my amplifiers wattage? What's going on? Just curious, I love the amp, thanks, Dave.

Myles. Welcome back, Dave (the Dude).

Hi Myles , It's me again, Dave (the Dude). On the original posting above, SRB (after telling SRVfender to see you, the tube guru) said, "your phase inverter tube is a MOST important tube." Do you agree? Do you agree about replacing the phase inverter tube everytime you replace the power tubes? Again, thanks for your help and for your prescence here and expertise and your support of this forum. Dave, the ignorant.

Myles, This two questions. 1) What is bias? I'm an (Mechanical) Engineer and I may be a little weak on this, but as far as I know the only three things that matter to an electrical device are Volts, Amps and Resistance. Which is bias? Are you (generically/plurally) adjusting the resistance to make the voltage or amperage correct? If so, what do you look for. I have a wealth of equipment available to me and I'm fairly good at this kind of "stuff". Can I do it myself? 2)This is a repeat and I already know that your opinion is it's too complicated. BUT, if I want to do it anyway, is there any HARM in switching "hot" tubes (via circuit) to change from EL34's to 6L6's? Thanks for any help you can offer. You're a wealth of knowledge and feel very fortunate to find someone as knowledgeable as you that is willing to help ignoramuses like me that need help. Thanks, Dave.

Is it possible on my Randall Pro-Tube 1000 (has a bias switch for 6L6 or EL34) to set up a parallel rung (of the circuit) for another set of power tubes with a (ON/OFF) switch and an On/Off switch for the exitsing circuit? This is to switch from one type of tube to another while they are still hot. Maybe just a pipe drean.

Myles, I went to www.tubesandmore.com as you recommended and they have QUITE a few books on tube amps. Are there any that you can recommend for a neophyte like myself that wants to understand how the amp works and what type of tubes to put where? Dave

QUOTE Myles, more on the Randall Amp (or any amp, I guess). I figure the two power amp tubes (6L6 or EL34) are one for clean channel, one for dirty channel. How do I know which one is which? There are four pre amp tubes. What are they for? Should I use different types (i.e clean and dirty channels)? Sorry for the VERY basic questions, but I'm still a neophite at guitar ELECTRONICS. Thanks, Dave Phoenix. -------------------------------------------------------------------------------- QUOTE Dave, The power tubes always work together ... clean or dirty. The preamp tubes are generally for your first and second gain stages, and the last preamp tube is the phase inverter that drives the output tubes. Other preamp tubes are for effects loops, reverb drivers, and vibrato drivers. Myles Myles, Is there a way to KNOW which tube is first gain, second gain, phase inverter, etc.? Do all tubes need to be of equal quality and / or output? Lastly (I, and I imagine, you, hope), I have four tubes, and one is first gain, one second gain, one phase inverter and I have BOTH reverb and effects loop what's going on? That would be five tubes! I'm just trying to understand if I need to spend the same (high) amount of money on all four tubes. I thought I remembered you saying someplace in this ongoing posting, that a certain tube or tubes was not as important to be high quality. Thanks for any help, Dave.

Myles, more on the Randall Amp (or any amp, I guess). I figure the two power amp tubes (6L6 or EL34) are one for clean channel, one for dirty channel. How do I know which one is which? There are four pre amp tubes. What are they for? Should I use different types (i.e clean and dirty channels)? Sorry for the VERY basic questions, but I'm still a neophite at guitar ELECTRONICS. Thanks, Dave Phoenix.

I've finally got my 1993 Randall Pro 1000 II amp. I checked the tubes before I turned it on (it's warming up now). The Pre-Amp tubes are "Randall" brand (I assume original 1993) 12AX7A. Can I do better? The amp has a bias switch for EL34 or 6L6. Right now it has Sylvania (looks like )626 ABU tubes in it. Can I do better than those? The EL34's are Chinese tubes. What's your best suggestion for their replacement? I know this is a lot and very general, I'm just looking for some place to get started.

quote: -------------------------------------------------------------------------------- Originally posted by Dave th Dude: Myles, I am just about to receive (it's shipping today) my first tube amp (Randall Pro 1000, 1993). I seem to remember somewhere in the deep, dark recesses of my memory (boy it's scary in there) something about the handling of tubes that said the oil from your fingers (that create fingerprints), if left on a power tube, will create a hot spot and cause early failure. Is there any truth to this? Or was I just smoking wacky tobacee? Dave -------------------------------------------------------------------------------- quote: Dave, I guess from a pure physics point of view this may have some point, but tubes are not like halogen bulbs. They are more like conventional light bulbs, and I do not wear gloves when I replace light bulbs or tubes. The main point of handling tubes is .... watch out for leaving some of your skin on output tubes when they are super hot ... won't hurt the tube much, but causes people a bit of pain Regards, -------------------- Myles S. Rose That's IT ! Halogen bulbs. I knew I remembered that from somewhere. I don't wear gloves to replace light bulbs either. Thanks for jogging my web clouded memory, Dave.

Myles, I am just about to receive (it's shipping today) my first tube amp (Randall Pro 1000, 1993). I seem to remember somewhere in the deep, dark recesses of my memory (boy it's scary in there) something about the handling of tubes that said the oil from your fingers (that create fingerprints), if left on a power tube, will create a hot spot and cause early failure. Is there any truth to this? Or was I just smoking wacky tobacee? Dave

I just bought (have not received yet) a '93 Randall Pro 1000. It has a bias switch to switch between 6L6 tubes and EL34 tubes. The seller included a pair of 6L6 tubes in the deal. During emails back and forth (before buying) about the "sound", the seller (an amp repairer) said that another trick (he mentioned many with controls that would "soften" the sound) was to put in 6L6 tubes and set the bias switch for EL34. That the only negative would be that the life of the tubes would be shorter, but it gave a "..REAL nice hot overdrive sound out of it this way." When I posted this info on Guitar Forum to let everyone know I had FINALLY bought a tube amp, what it was, the seller's comments about its versatility and to thank them all for their help; Gabriel replied that when the tubes "blew" they could wipe out some other parts of the amp. When I asked if there was a way to avoid that, he referred me to you. What should I do?