 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
172.164.128.197
I'm looking at getting a used, self-biasing E34L amp from the dealer/distributor, and he says that only the exact types and brands of power tubes and input tubes that come with the amp should be used. The warranty that I'd get with the amp would be voided if I use anything else.
I'm not a tech type or a huge tube roller--I don't really know what diff there is between an EL34 and an E34L, for example--but why would it be a bad idea to use the same tube types from another manufacturer, or direct substitutes, in an amp? I like the 6CA7, for instance, but that would be unrecommended, according to the dealer.
This is the first time I've encountered an amp limited, at least for the term of the warranty, to only particular tubes. I don't have a big problem sticking with the tubes that the dealer recommends, but it does seem a bit unusual.
Any thoughts about why a particular amp might be so picky?
(I'd be glad to give the i.d. of the amp in a private email, but this is a more general question about whether some amps don't like to be tube rolled and some do. I also don't want it to appear that I'm picking on the amp or the reputable and, from experience, good-guy dealer.)
Follow Ups:
In terms of type of tube, as a general rule, it's a good idea to stick to the same type of tube (e.g. 12AX7, of whatever brand) as the amp was designed for. Changing to another tube type (say, substituting a 12AU7 for a 12AX7) is often not a good idea because the tube parameters are different enough that the other tube type is not working in an optimal fashion, i.e. it may be running at a higher distortion point. Some designs may be more tolerant of this but generally a circuit is designed to be optimal for the tube type specified.
In terms of changing to a different brand tube of the same type, e.g. substituting an RCA 12AT7 for a Sylvania 12AT7, if it is the same type it is designed to be interchangeable in terms of tube parameters - if you look at the published tube specifications from different manufacturers for the same tube, the numbers are identical, so the warning against changing brands is complete and utter bullshit.
In any event, the warranty presumably is not forever, and if it is a reasonably designed amp, the original tubes should last for at least as long as the warranty, at which point you are free to substitute whatever your heart desires.
This is a very smart recommendation from the manufacturer. Rolling a bunch of tubes through an amp wears out the sockets prematurely.
But if you don't roll tubes, how can you tell what sounds best in the amp?
Rolling tubes is one of the joys of tube amp ownership. It makes your amp a "hobby" for many people. You would think tube amp manufacturers would get that?
Now if you have cheap, crappy sockets in your amp, then you should change them. If you have decent quality sockets, I say roll on!
If you are careful inserting and removing the tubes (take your time don't rush), along with cleaning and retentioning on a regular basis, tube rolling does not have to wear out your sockets. I have rolled hundreds of tubes and my sockets are just fine thank you.
Enjoy the roll!!!
Thanks to all for the replies. Best I can tell, there are at least two things going on here (maybe more): one legit, one not so much. First, it seems the output trannies for some amps are more narrowly specc'd and built for one kind (or many just a couple or three) of tube, something that someone as tech undereducated as me wasn't aware of. A.J. said here in '07, as I found: "Using KT88, KT66 or 6550 would require some changes in the output transformers that being custom and handmade for the EL34 output impedance, seems to me quite unpractical. Other amplifiers using different circuit implementation and not application optimized trannies, can use different tubes."
Second, it seems to be a case of a manufacturer prescribing only one way as far as tubes/operation/associated equipment, etc. go. The irony, as I discovered in poking around, is that the brand of tube the manufacturer says is the only one to use is so bad in current production that Kevin Deal and Jim McShane won't even sell them. Go figger.
Nonetheless, it does seem that some fixed-bias amps are more tolerant than others in the tube-rolling line. It's just that it appears a little less than biblical that only one kind of tube, let alone one brand, has to be used in a particular amp.
It reminds me of a very expensive Italian-made integrated amplifier whose manufacturer and local dealer urged me to use only the stock tubes when it started to blow fuses. I believe it is a very poor and distriminating approach.
Does your amp employ PCBs? It looks like it does - from my experience, most of such amps are much less reliable than those employing point-to-point wiring.
Don't think it's the amp that's being picky.
Pray tell, how would/could he possibly know if you used some other type of tubes in the amp?
Seems completely ridiculous on his part and unless you are dead
set on that particular amp (for whatever reason), you may want to
buy elsewhere - even the same model.
"Once this was all Black Plasma and Imagination" -Michael McClure
You state this is a "used" amp. That being the case perhaps the warranty is being provided by the dealer and not the manufacturer. The dealer may or may not privy to tube rolling experiences with this product so is being cautious.
As for tube rolling under manufacturers warranty, I know of a reputable one that encourages rolling, while the other manufacturer will void the warranty.
On the flip side, there are reputable tube dealers that will ask what amp you have. I've had tube dealers refuse to sell me certain brands even though identically spec'd tubes.
So the short answer is... circuit design can dictate tube options.
Cheers!
Jonesy
"I know just enough to get into trouble. But not enough to get out of it."
I'm sure the dealer isn't saying this to sell a relatively inexpensive extra set of tubes to me (the amp comes with a tested set), so that's why I'm puzzled the warranty is being made dependent on using only the supplied tubes.
I understand that being able to bias an amp if you're using various types of a tube (EL34, E34L, 6CA7, KT77, whatever) is better, but I'm stumped why only one kind and one brand are being recommended.
mt
The idea being if the amp came with "red" matched output tubes, you only need to buy new "red" ones and plug-&-play.
Problem is... for some reason or another, the "matching" wasn't all that well done throughout the years of tube production. So, you'd still needed to adjust the bias.
Are you sure that this is not just the distributor talking?
Be interesting to know as MOST self biasing EL-34 amps not so fussy about the brand of EL-34 one uses.
Tube types, perhaps.
Brands? Would be interesting to know.
Does the dealer sell tubes? This is nonsence
Alan
It appears that the tube in question is An E34L made by JJ. They can be sourced from a large number of dealers, not just the guy who sold the amp. There are unsaid but implied concerns expressed by certain amp brands that encourage you to replace tubes from them, usually at much greater cost than a tube dealer. We all know some of these manufacturers.
I used the Blue glass version it was much better than Red.
I don't know about you But how many times has the old tube box your last tube roll came in e.g. Baldwin, implored you to 'replace with only genuine Baldwin brand tubes. This sounds a lot like what was said here except there were no warranty implications. They take it for granted, that you never would replace with some other type tube as in rolling 9 pins e.g. using a 12AX in place of a 12AT7.
It is also true there are amps that encourage rolling these days. Like the Garage 1217 Project Ember headphone amp. There are examples to experiment with various output tubes and amps.. Ask Uncle Kevy on this about certain amp are indeed tolerant of rolling the output various tubes within reason
Steve
Post a Followup:
| FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
||||||||||||||
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2024, Audio Asylum, all rights reserved ]
