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Old 27th April 2012, 02:34 AM   #21
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I'm kind of fond of the Sovtek 12AX7LPS,it's a long-plate variant,with a spiral filament for low noise. Reasonably priced too.
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Old 27th April 2012, 10:48 AM   #22
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Originally Posted by jim1961 View Post
I have an A.R.T Dual Tube Parametric EQ that uses 12ax7a tubes. The present tubes say Phillips ECG 8752 aja, Jan 12at7wc


I am not well versed on tubes so I have some (silly) questions:

1) Are all 12ax7a tubes the same in regards to their use? In other words, is a 12ax7 the same as a 12ax7a? What does the "a" at the end mean?

2) For audiophile purposes, what tubes would be recommended for this type of application?

What little I know about tubes tells me that they can have different characteristics, like low/high distortion. Some tubes sound more "tubey" than others. Some are warmer than others. So I may need help defining what type of tube, or the sound I want from them. But going on what I know to this point, id say:

a) low distortion
b) lots of midrange warmth
c) as transparent as possible
d) moderate as to how "tubey" they sound.
e) under $75 a pair?

any suggestions?

The people art A.R.T. recommended Electro-Harmonics tubes.

I am looking for high quality. To improve over the original tubes.
Do yourself a favour and get some matched 60's NOS RCA 12ax7 tubes.
Regardless of audiophile jargon and such hardware ~ IMHO the RCA tubes go back so far and they "are good" - really good, they set the industry standard. They are a bit costly , but if you are patient you'll get a good deal on Ebay.
Cheers.
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Old 27th April 2012, 12:27 PM   #23
jim1961 is offline jim1961  United States
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Originally Posted by Archibaldy View Post
Do yourself a favour and get some matched 60's NOS RCA 12ax7 tubes.
Regardless of audiophile jargon and such hardware ~ IMHO the RCA tubes go back so far and they "are good" - really good, they set the industry standard. They are a bit costly , but if you are patient you'll get a good deal on Ebay.
Cheers.
I have heard great things about the RCA's.

12AX7 Tubes in Stock

I found some at the above link. Except for the "butt ugly" ones, the matched pairs are out of my price range. Think I ought to try the "butt uglies" ????
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Old 27th April 2012, 12:52 PM   #24
AJT is offline AJT  Philippines
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what issues are you having with you gear? i'd say just put in a 12ax7 and be done with it....rolling tubes will loosen your tube sockets and then you will have another issue....
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Old 27th April 2012, 01:05 PM   #25
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Originally Posted by jim1961 View Post
I have heard great things about the RCA's.

12AX7 Tubes in Stock

I found some at the above link. Except for the "butt ugly" ones, the matched pairs are out of my price range. Think I ought to try the "butt uglies" ????
Hey Jim,
Howdy doody !
Yes mate, go for the butt ugly ones, I've got several pairs myself.
They may not look like jewellery but if'n they be RCA and strong they'll get the job done much to your delight !
Don't forget , all new tubes need quite a few hours to "burn in" (run in).
Then, when you're satisfied and have a favorite set, then start experimenting with other brands- you can always fall back on the good'ns.

Hope this helps, careful not to go broke as I've been bitten and I've seen some 12ax7's go for thousands, (Rather absurd, but...)
One thing is definately needed ! ~ A JOB !!!
Cheers,
Andrew.
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Old 27th April 2012, 01:11 PM   #26
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Originally Posted by jim1961 View Post
I have heard great things about the RCA's.

12AX7 Tubes in Stock

I found some at the above link. Except for the "butt ugly" ones, the matched pairs are out of my price range. Think I ought to try the "butt uglies" ????
Me again,
I've been looking at the link you supplied, it is very informative - I have been there before.
Don't rely on just one source for tubes etc ... check ebay, there are many available.
Cheers.
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Old 27th April 2012, 01:22 PM   #27
jim1961 is offline jim1961  United States
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Me again,
I've been looking at the link you supplied, it is very informative - I have been there before.
Don't rely on just one source for tubes etc ... check ebay, there are many available.
Cheers.
One of the problems I am having is the shear magnitude of choices. Even limiting myself to only NOS RCA, they are tons of options. I just feel overwhelmed as to decide how to go on this venture. Not to mention that Mullard, GE and Genalex NOS tubes are also highly regarded.
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Old 27th April 2012, 02:06 PM   #28
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Originally Posted by jim1961 View Post
One of the problems I am having is the shear magnitude of choices. Even limiting myself to only NOS RCA, they are tons of options. I just feel overwhelmed as to decide how to go on this venture. Not to mention that Mullard, GE and Genalex NOS tubes are also highly regarded.
Yes Jim, I understand full well the dilemma of making a choice.
And yes again, there are Mullard, GE, Sylvania,Raytheon/Baldwin,older Sovtek 12ax7LPS(long plates) & others, all of them are good tubes.
I try to stick to the rule of thumb that RCA were there before the others and I know for a fact (my ears) and the spooky looks from my Pink Floyd loving neighbor and the lack of complaints about the volume, bass punch, the shimmering glassy highs & crystal clear vocals (from other neighbors).
Hey man, I am hearing vocals so clear I can understand nearly every word, often I used to think the words were different
And the seperation of the instruments is almost to die for.... well.
I'm not saying you must get RCA the choice is yours,
Need more help ?
Cheers !
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Old 27th April 2012, 04:31 PM   #29
jim1961 is offline jim1961  United States
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I heard back from A.R.T.

Hello Jim,

Either are fine. The specs in the manual say AX, but it's possible AT's were substituted. You can run either without harm.

I recall that a similar change was made in the ProVLA- it was designed and spec'd for AX7's, but after a few runs, we did some A/B listening tests and most of us thought AT's sounded better, so they were used from there on out. But the manual specs always said AX7, with the caveat "specs subject to change without notice" covering the difference.

I don't recall a similar change with the TubeEQ, but it would explain what you found.

So, what are peoples take. AX or AT ?
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Old 27th April 2012, 04:37 PM   #30
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I went through a few of the 12ax7 tubes and 12at7. In the 12ax7 circuit (voltage amplification stage) use of 12at7 usually produces thinner sound - but it greatly depends on schematics - a lot of people, including myself, hate 12at7 in 12ax7 slot due to a squeaky sound it produces.

As far as 12ax7 goes, it depends on the sound you want to get at the end. Telefunkens will bring brightness and air; Mullards will bring midwarmth, but not as much details; Amperex is a middle ground between the two. If you want midrage shine try Mazda. My favorite is Sylvania 5751 gold brand - but it's very expensive. RCA with D getter and charcoal plates (as opposite to shiny) produces very good bass, very warm sound, but still has a lot of details.

Stay away from current production. They cost more than old stock, but have a mediocre sound. Example - current price for the aforementioned RCA is $30-40 on Ebay. With Genelax Reissue, you will pay about $39.

I'm bloging my experiences with tubes here. Hope it helps:
12Ax7 | Tube Maze
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