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EL34 or 6CA7 difference???

rodl2005

rodl2005

Jun 1, 2005
19,567
15,063
Tasmania, Australia
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#1
Hi guys,
was just reading the "Musicman HD130" thread re the output tubes & was wondering-as I have a similar problem with my Aus. '70's amp, :eyebrow: - whats the difference between the EL34's & 6CA7 tubes I realise U reccomended the 6CA7EH 'big bottle" type & this is probly what I need for my amp, But I was Just wondering?????:hmm:
Cheers,
Rod.
 
#2
I just read the thread on the OTHER MM HD 130 & found out that 6CA7's are the US variety of Euro EL34. Thanx PBG mainly- looks like I'll have to try the 6CA7EH big bottle as my Aussie '70's amp puts out nearly 700V on the plates! Do U reckon these tubes 'll be able to handle the voltages- as I just bought some EH EL34's-6 of - & it only lasted 1 gig B4 a tube broke!!!! I need some gutsy tubes! Someone reccomended jjKT77's what do U think of these?????

Rod.
 
#3
rodl2005 said:
I just read the thread on the OTHER MM HD 130 & found out that 6CA7's are the US variety of Euro EL34. Thanx PBG mainly- looks like I'll have to try the 6CA7EH big bottle as my Aussie '70's amp puts out nearly 700V on the plates! Do U reckon these tubes 'll be able to handle the voltages- as I just bought some EH EL34's-6 of - & it only lasted 1 gig B4 a tube broke!!!! I need some gutsy tubes! Someone reccomended jjKT77's what do U think of these?????

Rod.
Click to expand...

6CA7's and true KT77's are beam tetrodes. True EL34's are pentodes. Typically, fat bottle 6CA7's can handle more voltage and have better low end. KT77's tend to handle high voltage also, but are sonically more similar to true EL34's. If you're replacing tubes yourself, it doesn't matter what type you get, without a bias job theyr'e NOT going to run properly.
 
#4
Hi:

As a HD130 (with the 12AX7 driver tube) player for 30 years,
I can vouch for the 6CA7. Much better tube for this amp.
I've tried EL34s and they just don't sound as good.

Best ever was Sylvania big bottle 6CA7's, worst was
Sovetek/Tesla EL34s. Currerntly I have Electro-Harmonix 6CA7EH
tubes which work fine (probably relabeled Sovtek's), but
my tech said they handled the high plate voltage quite
well and have a nice beefy low end at low volumes

Phil Anderson
Tucson, AZ
 
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#5
Thanx for the replies!
PBG- I am getting the amp seen to by a tech, but as I live in a smallish city in an Island state of Aus-good tube techs are rarer than -well there's one-& he's soooo busy he won't even touch my gear!!! The guy I've got doing it is fine & rebiased the amp fine but he doesn'r LOVE tube stuff & his 'hearts' not in it & he doesn't know re which tubes are the best etc etc.....
Thanx also Ander... I'll look into the 6CA7EH big bottle I think-this seems to be the best I've come across lately-pity I didn't know about this B4 I bought the EH EL34's =rubbish for my amp anyway!!!:bawl:
Rod.
 
#8
rodl2005 said:
Yeah I may try the 6CA7EH big bottle but I'll have to save up damnitt! as I just recently bought 6 EH EL34's, now they're next to useless save a cheap re-sale:mad: :crying:
I didn't know B4 that U could swap tubes types, but as my tech says U can & just have to rebias! anything else I need to know????:ninja:
Rod.
Click to expand...
You can't swap all tube types, especially in such a high voltage amp as a MusicMan. Only certain types can be changed, and even then it may not be a good idea. Make sure you have your tech do the work, it is very dangerous to work with the amp if you are not properly trained.
 
#9
Plain Old Me said:
You can't swap all tube types, especially in such a high voltage amp as a MusicMan. Only certain types can be changed, and even then it may not be a good idea. Make sure you have your tech do the work, it is very dangerous to work with the amp if you are not properly trained.
Click to expand...

Yeah I know this & my tech will be doin ANY tube changing!!! I'll most likely just save for the 6CA7EH's a set of 6 needed! Thanx
Rod.:hiding:
 
#11
:eek: SORRY if I mislead U guys, BUT mine aint a Music man, just a great tube tech in my town-one thats too bust to look @ my gear for a year- was describing to me how the MM had the same prob. of HIGH plate Voltages as MINE. Mine is an Aus. 1978 Eminar amp. Uses 6x 6CA7's after 15yrs of never pushing the amp a couple of the power tubes went bung-(surprise surprise!!!) so I bought the set of 6 matched EH EL34's as I was told & read etc that they were the same as EL34's- didn;'t know then that tubes today & ones of yesteryear were nowhere near the same- I DO NOW tho!!
Cheers,
Rod.
 

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