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Best preamp for testing tubes

#61
In case anyone is interested, here is a list of some of the tubes that I have on hand. I am probably forgetting some. It's a mix of new and NOS, and it should be obvious which is which. I have multiples of most of these. As you can tell, I am going to be at this a while!

Tubes on hand for evaluation:

Amperex Bugle Boy 12AU7
Amperex ECC83 (Siemens, and several others)
Dumont 6681/12AX7
EH 12AX7
GE 5-Star 5751
Groove Tubes Mullard Reissue
Heath (by Mullard) 12AX7
JAN GE 12AX7WA
JAN GE 5751
JAN Philips 12AT7WC (blackplates)
JAN Philips 12AX7WA
JJ 12AX7A
Motorola 12AX7A
Motorola by GE ECC83 12AX7
Mullard 12AT7 CV4024
Mullard 12AU7A
Mullard ECC83 12AX7
Raytheon JRP Black Plate 12AX7
RCA 12AT7/6679
RCA Black Plate 5751 (3 mica, square getter)
RCA cleartop 12AU7
Shuguang 12AX7C9
Sovtek 12AX7
Sylvania 12AX7A/ECC83/7025
Telefunken ribbed ECC83
Telefunken smooth ECC83

If anyone has any suggestions or comments regarding any of these tubes, feel free to fire away. I am hoping to compile my thoughts/observations on most, if not all, of these tubes in the bass gear I have on hand and post this on my blog.

Later, Tom.
 
#66
Well, I spent some time tonight swapping tubes in my Demeter 201s, and I think I am going to stop monkeying with the Dem, and use the DB 659 for testing. The little circuit boards that hold the tube holders in the Demeter are a bit more sturdy than the F-1X (I think just because they are less wide), but still make me nervous. The 659, or 680, are pretty much worry free. Of course, I could also wait until Joker's Purity arrives! :p

FWIW, for testing so far, I am using a CA9 powering my El Whappo, and I'm using either my Sadowsky or my Skjold. Of the tubes I tested, my favorite has been the NOS GE Black Plate 5-Star 5751. It has a great balance of warmth/smootheness versus clarity/precision. The Mullard CV4024 is great in the smooth/full thing, and takes a bit of the edge off the highs (probably a good thing with the 201s), but was not as articulate as the 5-Star GE. JJ ECC83S is just a killer tube, with superior clarity, but it might be too much of a good thing in the Demeter. Several other tubes sounded fine, but didn't really stand out.

More to come!

Tom.
 
#67
tombowlus said:
Well, I spent some time tonight swapping tubes in my Demeter 201s, and I think I am going to stop monkeying with the Dem, and use the DB 659 for testing. The little circuit boards that hold the tube holders in the Demeter are a bit more sturdy than the F-1X (I think just because they are less wide), but still make me nervous. The 659, or 680, are pretty much worry free. Of course, I could also wait until Joker's Purity arrives! :p

FWIW, for testing so far, I am using a CA9 powering my El Whappo, and I'm using either my Sadowsky or my Skjold. Of the tubes I tested, my favorite has been the NOS GE Black Plate 5-Star 5751. It has a great balance of warmth/smootheness versus clarity/precision. The Mullard CV4024 is great in the smooth/full thing, and takes a bit of the edge off the highs (probably a good thing with the 201s), but was not as articulate as the 5-Star GE. JJ ECC83S is just a killer tube, with superior clarity, but it might be too much of a good thing in the Demeter. Several other tubes sounded fine, but didn't really stand out.

More to come!

Tom.
Click to expand...
Interesting.

Sounds like the CV4004 would work well in the Dem and the GE 5751 in most of the higher gain preamps (like to hear a BBE BMax-T with one).

I bet the JJ would be good in the DB659 (for de-wooly-fying) and maybe some of the warmer Pre's like Alembic, Kern, & Ampeg.

Thanks again, Tom.

[Edit:] Oops! My bad. The CV4004 here should read CV4024 (the lower gain version -- corresponding to a 12AT7, where the CV4004 is the 12AX7 type tube).
 
#68
tombowlus said:
Well, I spent some time tonight swapping tubes in my Demeter 201s, and I think I am going to stop monkeying with the Dem, and use the DB 659 for testing. The little circuit boards that hold the tube holders in the Demeter are a bit more sturdy than the F-1X (I think just because they are less wide), but still make me nervous.
...
Click to expand...
P.S. When swapping tubes in my 201S, I usually get a death-grip on the socket.
If you make sure the tube pins are pretty straight, this seems to do a good job of removing the stress from the circuit boards.
Those Demeter's are put together pretty well.
 
#69
lo-freq said:
Interesting.

Sounds like the CV4004 would work well in the Dem and the GE 5751 in most of the higher gain preamps (like to hear a BBE BMax-T with one).

I bet the JJ would be good in the DB659 (for de-wooly-fying) and maybe some of the warmer Pre's like Alembic, Kern, & Ampeg.

Thanks again, Tom.
Click to expand...

I think that you are right about the JJ's in the 659. I'll have to try that. And so far, I haven't tried out my Mullard CV 4004 yet. That was the 4024 I was talking about, above.

Tom.
 
#71
carl-anton said:
Tom, how's the low end of the GE 5751?
Click to expand...

Very nice. A slight roundness, but overall still tight. Plenty full.

carl-anton said:
And is it a 1950's production tube?
Click to expand...

I am not sure on the production date, but that sounds about right. I could find out from Doug Preston, if you were really curious.

Tom.
 
#73
Okay, first off, I have to apologize for starting off this thread, and then being such a slacker so as to not follow up on testing all of these tubes. My work has been very busy, and my schedule has been such that I just don't have that much time to "play", and what time I do have is normally when the kids are asleep, so that limits things, too. But, in an effort to make "progress" - and in response to popular demand! - I did manage to add the following preamps to the collection:

Jack Read Purity
Kern IP-777 (still en route)
Fender TBP-1 (still en route)

I am hopeful that the Kern is the ticket for testing tubes, because even though the Read has the access at the back of the unit, it is not all that easy to pull each tube out, since not much of the tube sticks out. So far, the 659 is the most easy to swap tubes, and it definitely shows off the characteristics of the tubes, but I hate leaving the top panel off of a unit for so long.

I also have a Demeter VTDB-2B on the way from Tommix (thanks, Tom!), and with its boost setting, it may be loud enough to use as well. My Aggie DI doesn't get quite loud enough straight into my CA9 to work really well for this.

I'll update as I can!

Tom.
 
#75
Fuzzbass said:
Understood, Tom. I look forward to your tube reviews when you can get to them. Heck, I'm also interested in your thoughts on Fender vs. Read vs. Kern!
Click to expand...

In addition to the individual tube results, I am trying to find time to conduct the following:

Ultimate Preamp Shootout!
The SS Head Steel Cage Match!
Tube Head Slugfest!
Tube Ampathon!
The Definative SS Amp Comparison!

And more! :D
 
#77
Great work you've already done, and great work ahead Tom! Your comments on the GE blackplate 5751 NOS tube made buy one, and your describtion is right. I use the tube in my SWR 750, which from what I hear, doesn't sound the same as the Aguilar DB659, but the difference is to be described like you did. Perfect mix of warmth and clarity. So I guess there's some kind of generallity on how the tubes sounds, nomatter what amp you use.
 
#79
carl-anton said:
So I guess there's some kind of generallity on how the tubes sounds, nomatter what amp you use.
Click to expand...

I'm glad you like it! I do, indeed, think that a given tube will definitely impart its character into whatever unit you throw it into. What happens when all the factors intertwine is always a gamble, but the tube's contribution should be relatively consistent (although the amount of plate voltage supplied probably has a pretty big effect on how that tube sounds).

Tom.
 
#80
tombowlus said:
In addition to the individual tube results, I am trying to find time to conduct the following:

Ultimate Preamp Shootout!
The SS Head Steel Cage Match!
Tube Head Slugfest!
Tube Ampathon!
The Definative SS Amp Comparison!

And more! :D
Click to expand...
I wish I were available to serve as your test-assistant for these. That'd be fun. :bassist:

Looking forward to the reports.
 

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