• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

12ax7, 12ad7, 7025...................

dread31

dread31

Addicted Member
Greetings,

I have a new Pro-Ject Tube Box S enroute which has prompted my to go through my tube stash in search of rolling stock.

So far, I have found one pair of Tung-Sol 12AX7, a pair of RCA 7025 Black Plates, a pair of Sylvania 7025 Grey Plates and a pair of NEC 12AD7s...........

As I understand it, these are all good candidates for some fun tube rolling in the Pro-Ject. Some of them fairly rare and sought after, apparently.

Has anyone had experience with any of these?

Dave
 
Register to hide this ad
No experience with those but the TubeBox ds that I have responded well to rolling. I would like to try the rca black plate myself. Good choices and have fun.
 
The 7025's were originally meant to be low noise variants ("selections" from the same product line) of regular tubes. Many were used in phono sections and in industrial equipment. I have found them to sound mostly the same as their regular production brothers of the same manufacturer.
 
5751's would also be a good choice , early made 7025's are not any better than latter made USA 12AX7's or British / German made ECC83's if as good .
 
I have not found a better all around tube than the RCA late 50's 7025 black plate, full warm mid range, solid base and sensational realism. I only have the one pair that I got from Andy at Vintage Tube Services. If these are what you have treat them kindly. The 60's version of RCA 7025's, I agree are nothing special.
 
I'm wondering about the 12AD7s. As I understand it they are supposed to be a "Professional Grade" with even lower noise and microphonics. They also have smooth plates.

I saw some 12DF7s on ebay going for stupid money. Research reveals those are the "Laboratory Grade", ultra-precise 12AX7 variant.

Dave
 
I wish this thing would get here. I keep looking out on the porch. From NYC to S.E. Virgina should only take a couple days, right?

Dave
 
Most grading was done for specific customer groups like the military, instrumentation makes, etc. For the most part sound was never even considered. Usually you had selections from the same lines all their other tubes were made in. Sometimes you had extra rods and mica to ruggedize the tube for vibration environments (think military) and other requirements. In my experience the main benefit is often better matched halves and less noise, but not necessarily better sound. I have 5691 and 5692 tubes for example that sound indistinguishable from their 6sn7 and 6sl7 brothers. Same with 7025 and 12ax7. So, before you go paying big bucks think about what you are trying to accomplish - if what you want is to tweak tone, not deal with noise issues or needing equal triode halves for a circuit, then go across manufacturers/brands rather than worry about fancy grades of the same tube by the same maker. YMMV of course.
 
Agreed, Goldleaf. It makes perfectly good sense to me, that design variations and materials used would make the greater difference in sound.

Although, I tend to think that things like lower noise floor, lower microphonics and precise matching of halves would make some difference in sound as well.

Dave
 
You must log in or register to reply here.
Back
Top Bottom