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[iceland]

Καλημερα σε ολους.

Ποια η διαφορα μεταξυ EL34 και της EL34L

 

[thanasis k.]

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για διαβασε λιγο καποιες γνωμες

According to Roger Crimm with Peavey, EL34L's aren't true EL34's (don't conform to the spec) and Peavey is getting a lot of XXX's in for service because of them. Here is a direct quote from one of Roger's public posts at the Peavey Amp forum:

"I can't speak to what complaints Bob has received, but we have certainly seen more than one customer who has had a problem with that particular tube [the JJ EL34L]. Here is notice once again, just so there is no confusion. Note that this information comes from the company and engineering staff which designed the amp, and not from a tube vendor:


The GT-E34-LS may not operate correctly when using 100 Ohm screen resistors, even though that is the recommended value in the Telefunken manuals. Since the Triple XXX amplifier conforms to this recommendation, this tube is judged unsafe to use in this amp unless the amp is modified.

NOTE: Telefunken is only being mentioned here because they instigated the original and accepted EL34 spec.

These particular Tesla/GT "e34L" parts are only really safe in amps with screen resistors which are larger than what Telefunken recommends for an EL34 design. They are not, in our view, true EL34 parts. They are a newer design made to draw more current and produce more power. The "e34L" name was used universally on these to set them apart from EL34s.

The manufacturer probably assumed that all EL34 guitar amps had large chokes and/or screen resistors to provide screen regulation like many older designs have. It is recommended that any amplifier with 100 Ohm screen resistors using this tube be modified with a larger value resistor (700 to 1K Ohms)."


From what I've read, the E34L only draws 3 plate volts more then the standard EL34. I personally think that Peavey has changed specs in the XXX amp parts after they issued the statement, so that the E34L would be un-useable completely. The reason I think this is because I've personally talked to Bob and he's told me that he's got over 300 XXX users using E34L's, and only heard of one problem out of them all. And, according to the tech that fixed that one problem, the tubes wouldnt have been the issue.

From Bob:
"There has been a LOT of press lately about the JJ E34L's causing the Peavey triple X amps to blow up so I feel the need to get the truth out there. I'm getting between three to five calls a day now mainly from my regular Triple X customers either wanting to order the standard EL34's or wanting to know if the E34L's are going to cause their Triple X to blow up... Of course I don't mind selling all those standard EL34's but the truth of the matter is that there is absolutely no reason to worry about running the E34L's in your Triple X. The JJ E34L's do draw about three volts more than an EL34 does but this is a very, very small amount and if Peavey would have built these amps where they could not withstand this VERY small difference then you would see hundreds of Triple X amp owners posting all over the net about blown screen grid resisters caused by standard 6L6's and EL34's as they naturally age and start to fail. This is of course NOT the case.

This all started in April of 2004 when one of my customers ran a quad of the E34L's in his Triple X and the amp for some unknown reason decided to blow all four screen grid resisters and another resister in the bias circuit. Now I've been around tube amps for a long time and I've never seen any amp do this. Screen grid resisters or "fuses with pigtails" as they are known by most guitar amp techs will be the first thing to fail if a tube goes short and the regular fuses fail to do their job. For the screen grid resisters to fail in a Triple X the tubes would need to constantly pull 250 plus milliamps for a sustained period of time and there is not much of a chance that this will happen with this amp. I talked with the tech who repaired this amp ( Bob Wiegel at SoundDoctor'n ) and he shares my opinion about the fact that the E34L's were NOT and could not be the problem. I have over 300 Triple X customers out there using the E34L's and not one of them other than this isolated case have ever had a problem. Peavey sells sovtek tubes so they back them and will simply take any opportunity they can to let you know that JJ's wont work or will cause problems."

In my XXX I didn't take the chance, and I went with the JJ EL34, which sounds great by the way. I did this becuase Bob recomended changing the screen grid resistors to make it more reliable otherwise he said to use the standard JJ EL34's. He also says Peavey has made a production change and have started using 700 ohm resistors to replace the 100 ohm resistors. I guess thats where I get my opinon from about changing specs

Listen to Peavey. They built the friggen amp. They know more than Bob about this. The XXX will take out screen grid resistors if you use the E34L's. Part of the reason (IMO) that Bob hasn't heard of more problems is that the owners aren't aware of the failure. When a screen grid resistor fails that tube stops working. I can't tell you how many amps I've had come in that had bad resistors and the owners never knew. Since most of Bob's business is with do it your selfers that probably have no idea of how to check the resistors or bias an amp for that matter, they have no clue the amp has a problem. That's my opinion. Peavey uses a small screen grid resistor. It's a much smaller value than is commonly used. In most other amps you'll have no problem between EL34's and E34L's, and Bob would be correct. In a Peavey you will and he's wrong.
Jerry