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Tube rolling 12AU7 types in my ASL AQ-1001DT

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Posted on August 27, 2015 at 11:39:44
f1jim@yahoo.com
Audiophile

Posts: 57
Location: No. California
Joined: February 8, 2007
 Bought this Antique Sound Labs AQ-1001DT about 4 months ago and after 2 months replaced the Chinese KT-88's with Tung-Sol KT150's. That was a wonderful swap and after a couple of months it was time to start rolling the small signal tubes. It uses four 12AU7 tubes and I bought the amp used and it came with JJ 12AU7's with low mileage on them. I dug around and found I had at least four closely matched"

GE 6189 / 12AU7A
JJ ECC82
HP (Sylvania?) 5963
RCA 5963 black plates
RCA 12AU7A clear tops
Tung-Sol 12AU7A grey plates

That's them in alphabetical order. All tubes except the JJ's are vintage tubes waiting for a chance to shine. Now I will list them in the order I found them performance wise.

JJ ECC82
GE 6189 / 12AU7A
HP (Sylvania?) 5963
Tung-Sol 12AU7A grey plates
RCA 5963 black plates
RCA 12AU7A clear tops

I have read about all these tubes online and was surprised by my choices. The inexpensive JJ's had real magic with this amp. Tied with the most lifelike presence to voices with the GE's. The HP's were close behind. The Tung-Sols were good but didn't transport the singers into my room like the top three did. I would probably call it a tie for 4th place between the Tung-Sols and the RCA 5963 black plates. The RCA clear tops were the ones I thought would walk away with this comparison but were miles behind the other tubes. Thin sound throughout and a very transistor radio quality to the presentation. I was very disappointed as I had assembled a nice collection of them over the years but had never really put them up against anything. The huge surprise was the JJ's which everywhere I had read people were discarding them for better old stock tubes. I actually ordered a replacement quad of them after I finished the second go around of listening sessions.

Maybe it's this particular piece of gear? Maybe it's the mix of them and the KT150's? I don't have anything else that uses 12AU7's so I can't swap another piece of gear into the equation. I was pleased that most of the tubes I listened too I am quite pleased with, Anyone want to swap a quad of clear tops for something? Watcha think?
Oh, the ASL was running in triode mode. The speakers are Vandersteen 2CE's and a couple of older M&K V1 subs crossed at 50Hz. Best bass through the HP's
f1jim

 

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RE: Tube rolling 12AU7 types in my ASL AQ-1001DT, posted on August 27, 2015 at 11:54:57
Garg0yle
Audiophile

Posts: 859
Joined: December 1, 2014
 Did you test all these tubes?
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RE: Tube rolling 12AU7 types in my ASL AQ-1001DT, posted on August 27, 2015 at 12:32:04
f1jim@yahoo.com
Audiophile

Posts: 57
Location: No. California
Joined: February 8, 2007
 Yes, that's why I know they were matched. I matched them up on my TV-7.
f1jim

 

RE: Tube rolling 12AU7 types in my ASL AQ-1001DT, posted on August 27, 2015 at 13:13:10
Lew
Audiophile

Posts: 10911
Location: Bethesda, Maryland
Joined: December 11, 2000
 If your amplifier provides 6.3V filaments, you might try 6CG7 or 6FQ7, or if your amplifier provides 12.6V, you might try 12FQ7. They are all electrically identical or nearly so, to the 12AU7 or 12AU7 variant, but they sound way better, IMO. I think there is no re-wiring necessary, but check me on the filament pins. I do know that in a 12V supply, I replaced 12AU7 with 12FQ7 with no soldering required. Best 12AU7 I ever heard was the Amperex Bugle Boy, if you must stick to ECC82/12AU7.

 

RE: Tube rolling 12AU7 types in my ASL AQ-1001DT, posted on August 27, 2015 at 20:11:30
Blackdog
Manufacturer

Posts: 1505
Location: Ontario
Joined: March 20, 2006
 6V filament. You would need to re-wire the sockets to accommodate. Other than that the 6FQ7 will work. They may give slightly more gain, but not a lot. You could also try the 12BH7 on the inner two 12AU7's.
I am concerned about running the KT150 though. The extra filament current may be a problem.



Dan Santoni

 

RE: Tube rolling 12AU7 types in my ASL AQ-1001DT, posted on August 27, 2015 at 21:36:44
Garg0yle
Audiophile

Posts: 859
Joined: December 1, 2014
 Sorry i missed that.

Ya it's strange, but not really as these are mostly subjective opinions.
That being said, hold on to them, you might like them better in some other gear.

I have a preference for the clear tops and black plates as well.
Also thought the HP's sounded better then other grey plates.
I got a Philco that I really like too.

Most of my opinions (and others) are formed from using 12AT7's, 12AX7's, so I can't say how well that translates to the 12AU7s.

Your amplifier is probably some type of Chinese clone of some other amp, that might have something to do with it.
I don't mean that in a derogatory way, just who knows whats going on in there.

Use what sounds good and don't worry too much about it.

I agree with Blackdog though, check out the current on your heater string to be sure it can handle the KT150s.

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