12BH7A valve. Impressions? Insights?

[pankon]

I came across the 12BH7A valve for the first time, when I recently received my upgraded Croft Micro25R preamp (used in the line stage) and my Croft Series7R monoblocks.

Unfortunately the Sylvania 12BH7A (green lettering) of my preamp had a serious deficiency in the treble (roll-off), that led me to believe that it must have obviously been a faulty one. Currently I am using a Philips 12AU7 instead, which is quite good, but does not have such a full body in comparison to the 12BH7A. So I am looking for a substitute 12BH7A NOS valve to do justice to my Croft preamp.

Anyone with experience with 12BH7A valves? Which models are worth going for? Where could I find a good source for such valves? Is there perhaps a compatible substitute for 12BH7A valves, that is also worth considering?

Thanks in advance for any information.

Cheers,
Panos

[OD1]

Hi Panos,
I currently use a NOS Sylvania 12BH7A (yellow writing) in my 25, no problems with reduced treble, and prefer it to NOS Mullard, new issue Genalex ECC82, and supplied Sylvania 5814WA. I would say that the differences between these valves were not "night & day" but I felt that the 12BH7A gave a tad more depth, and a slightly more robust (firmer in the bass) sound.

When I asked my Croft dealer if the 12BH7A would be ok in my non regulated 25, & about the general sound of the different brands, his answer was "Tungsol warmest, GE brightest and Sylvania in middle", so I went for the Sylvania.

Having said this, I could happily live with any of the above valves, as none of them made the pre sound bad

Good luck tube rolling
Oliver

[pankon]

Hi Oliver,

thanks for your input. You said your pre is a Micro25, not a Micro25R. In its previous guise (before the upgrade), my Micro25 used to have an ECC82 valve for the line stage, not a 12BH7A.

In any case, my limited impression with the Sylvania 12BH7A is that it definitely has a 'bigger' sound, perhaps even sweeter than an ECC82 (or 12AU7).

Glenn Croft said that Tung Sol and RCA 12BH7A are good.

I have found a rather inexpensive version (obviously not NOS), which is https://www.tubesandmore.com/products/T-12BH7A-TAD. I may perhaps give it a try...

[OD1]

[QUOTE=pankon;735919]Hi Oliver,

thanks for your input. You said your pre is a Micro25, not a Micro25R. In its previous guise (before the upgrade), my Micro25 used to have an ECC82 valve for the line stage, not a 12BH7A.

Yes, my pre is not the 25R, but was told that the extra current requirements of the 12BH7A would not be a problem in my pre.
I intend getting mine upgraded to "R" status later this year, & I will ask Glenn to configure the linestage for a 12BH7A (as suggested by Jimbo in a previous thread).

[User211]

Above are some valves I sold with my Air Tight ATM2. So I did a few as you can see.

I reckon the best were the RCA long black plates from 1966 right next to the white boxes on the right.

Top left mid-70s Mexican RCA are good but not as good.

The black plates really are close to black with a kind of glossy sheen to them.

The Zaerix branded ones where also pretty damned OK I see to remember.

[User211]

Actually I may have some 12BH7A somewhere if anyone is interested give me a shout but it'll just be at market rates.

[pankon]

Above are some valves I sold with my Air Tight ATM2. So I did a few as you can see.
...

That's a pretty interesting collection of valves.

[Jimbo]

Above are some valves I sold with my Air Tight ATM2. So I did a few as you can see.

I reckon the best were the RCA long black plates from 1966 right next to the white boxes on the right.

Top left mid-70s Mexican RCA are good but not as good.

The black plates really are close to black with a kind of glossy sheen to them.

The Zaerix branded ones where also pretty damned OK I see to remember.

You wouldn't happen to have any RCA 12BH7a valves you want to sell Justin?

[Jimbo]

I have a NOS Tung-sol 12BH7a on the way for my 25R+ line stage which will replace the RCA valve I have in there at the moment.

Will be interesting to hear the difference!

[pankon]

I have a NOS Tung-sol 12BH7a on the way for my 25R+ line stage which will replace the RCA valve I have in there at the moment.

Will be interesting to hear the difference!

James, I would definitely be interested in hearing your impression. Have you tried any other 12BH7A apart from the NOS RCA? Is there a particular reason you would like to change to Tung-Sol?