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When to re-tube!

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walt bridge
Posted on Monday, November 29, 2004 - 05:57 pm:   

I have a 112rp 100 thats in good shape and works
fine.It has philips ECG 6ca7 el34 usa on the tubes. Iwant to re-place them ? and with what?
Steve Kennedy (admin)
Posted on Tuesday, November 30, 2004 - 12:46 pm:   

If an amp sounds good and exhibits no problems (loss of power, hum, overheat, no sound, etc.) there shouldn't be any operational reason to change the tubes.

If you want to save the older US tubes for future use in favor of something less expensive to wear-out now then that is a different story. Any good quality 6CA7 or EL34 type tube can be used as long as you get the amp biased for that style and manufacturer of tube.

Look at other postings in this and other areas of this Message Board (use the Search feature up in the corner to find things) to get user opinions of good tubes to look for. Since the Music Man amplifiers are operating these tubes at 700Vdc plate voltage you don't want some really cheap tube in there that might arc-over when in the high-power mode.

Steve

michael kaus
Posted on Friday, December 03, 2004 - 06:07 am:   

I have been spouting off about JJ tubes for a few years now and my opinion hasn't changed. They take the high voltage of MM amps when biased properly and keep on ticking. The E34L's are the version you want. At this time, they seem to be the bestat holding up and sounding good. Mike.
John Drexler
Posted on Tuesday, December 07, 2004 - 10:26 am:   

I gotta throw in a vote for Svetlana EL34's here, Mike. I've used them for years and they do a fine job and have held up very well for me with fairly heavy use in gigging. Of note, the "Flying C" label is the unit to specify, as there is a cheaper Svet also available that does not hold up as well. I have had no problem with them going microphonic, or failing prematurely due to the high MM voltage going through them.