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Post by John on Jun 29, 2007 6:04:53 GMT -7
I have a Maz Jr...that when I purchased it (used) I popped in a new set of matched JJ's. I always run the amp with the master on full. (Airbrake when needed)
So it's been about 18/24 months. I replaced the tubes with a the new spare set of JJ's....and I couldn't tell the difference. Granted, I was Airbraking quite a bit, so if there was a slight change in dynamics, it might have been squashed by the Airbrake.
So my question is: What are the characteristics of an EL84 that needs replacing.
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Post by kruzty on Jun 29, 2007 6:15:28 GMT -7
How often do you play it? Myles says you should be able to tell a difference around 300 hours. What exactly that difference is, I don't know...
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Post by stratosphere on Jun 29, 2007 19:29:27 GMT -7
I have a MAZ Sr. 1X12 combo. What I've noticed when the EL84's are going is the sound gets thinner and more "wirey" sounding. The highs get more icepicky and exaggerate pick sounds. The volume level will seem to drop and rise slightly, not drastic but enough that you will notice it. I play every day and my el's last around six months before I change them. They're still working but the improvement once I put in new ones is obvious. I've been using the JJ Teslas. I play a strat with Fralins and a G&L ASAT.
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Post by billyguitar on Jun 30, 2007 4:24:23 GMT -7
My Maz 38 was getting sort of tired sounding. As stated above thinner sounding and a little trashy. I retubed and all of the sudden I got this beautiful tone, super sweet mids and highs and the guitar would feedback at much lower volumes. It was a definite improvement. more than I've ever heard from a retubing before. The sad thing was that initial beauty went away pretty quick and then they settled down to almost that good and have stayed there for a very long time. Of course I quit gigging it about the same time. I would suggest a change at 300 hours or before, as recommended.
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Post by stratosphere on Jul 1, 2007 20:01:16 GMT -7
The great thing is that retubing the MAZ is relatively cheap, $50-$70 for a matched EL84 quartet. Billyguitar is right about the tone right after you initially retube. Which tubes are you using?
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Post by John on Jul 2, 2007 5:19:05 GMT -7
Brand new matched JJ's.
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Post by heynewguy (Ol’ Bill) on Jul 2, 2007 12:09:27 GMT -7
After further review, I like the new Groove Tubes better than the new JJ's. I know they are the same tube, but something has to be said for all that extra matching that Groove Tubes does. I only know this because I put my new JJ's and NOS tubes from my combos into my new heads. I just like the Groove Tubes better. YMMV
Bill
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Post by myles on Jul 6, 2007 17:01:47 GMT -7
I notice a change after as few as 30 hours ... about 10 shows. My critical clients change EL84 output sets about then. Some folks go a year! If you notice a big difference when you plug in a new set then start doing this more often.
This by the way is on most EL84 amps. EL34 amps can go 2000+ hours and 6L6 amps can easily go two times that long in most cases or longer.
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Post by mikekca on Jul 7, 2007 6:30:47 GMT -7
After further review, I like the new Groove Tubes better than the new JJ's. I know they are the same tube, but something has to be said for all that extra matching that Groove Tubes does. I only know this because I put my new JJ's and NOS tubes from my combos into my new heads. I just like the Groove Tubes better. YMMV Bill You should probably try again. It's not possible for the GT tubes to sound better because they're the same tube. There's always the possibility of a subpar or less closely matched (not that this even matters) set no matter what tubes you buy or where you get them. Also, unless you're doing blind tests (someone else does the switching and you don't know which tubes you're listening to at any point in time) and reach the same conclusion in 9 out of 10 tests, the test is not valid.
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Post by mikekca on Jul 7, 2007 6:32:25 GMT -7
The best way to know that your tubes are declining is to pop in a new spare set and compare them sonically. You should always have backups anyway especially since EL84s don't last too long (due to being run out of spec by today's amp designers).
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Post by myles on Jul 7, 2007 9:42:52 GMT -7
Since Mike at www.kcanostubes.com had to posts prior to mine here I thought I'd comment a bit. Mike is one of the smartest and most capable tube guys out there. He is also at the top of the list when it comes to being a human being and being a great guy to work with. The trouble many folks run into when they get a set of JJ EL84 tubes from most vendors is that even if matched to a degree in a simple manner they may (and usually do) fall outside of the range that work best in the Z amps. The Doc uses only #5 and #6 ratings from GT and the amps. Most users have no way to convert these ratings into numbers they see on their static based test equipment. Mike on the other hand not only sells his NOS offerings but he also sells a lot of new current production tubes as well. Mike is also one of the folks that is smart enough to be able to take a GT-EL84S #6 and look at the factors and numbers on the tube and convert this to a tube from JJ that will fall right into the proper range. Few other folks do this. Mike can also supply NOS EL84 offerings that will be in the same proper range as a GT #5-6 tube as well if you wish to go the NOS route. I have worked with Mike for many years and have sent countless people to him and will continue to do so. I have received nothing but thanks from folks for letting them know about KCA NOS tubes. I also recommend that anybody who has a new production vacuum tube rectifier in an amp contact him ASAP for ANY NOS version to replace the stock new production rectifiers. You will have an amp that is much more reliable and the current production rectifiers have ongoing continual problems. Mike's point above is quite valid .... if the tubes are of the same rating and current draw then there should not be a difference noted. But ... keep in mind that most folks just have some number like "37" on two tube boxes and even if this is something like current draw, unless the plate voltage and bias was known and displayed you may as well have any number from 10 to 10000 on the box. It means nothing to the end user. When I make up sets of tubes for my own clients or a SAG offering I only test at RCA / GE book spec voltages and the original spec is my reference point. I also supply sheets on each preamp tube that note the voltages, current output, actual true gain, transconductance, plate resistance, heater to cathode leakage and other things. An example of a out of the box ECC83S (JJ) before testing would look like this: As a side note .... for those that have been in my office at GT or at my house you know that I am surrounded by a lot of tubes and tube testing equipment but when I want something special for myself or a special client such as NOS stuff then Mike at KCA is my first call.
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