Requisite L2M tubes

[24-96 Mastering]

I read an old thread of Lucey, experimenting with exchanging tubes on the L2M. I have the feeling that that might be worthwhile. I love the unit but think there is room for improvement with regard to its "sound" (to my personal taste, of course).

Lucey, would you be so kind as to tell me what aspect of the sound of the unit led you to try out different tubes, which tubes were in the unit as stock, which different tubes you tried out, what they changed in the sound, and why (if) you didn't keep the L2M in the end.
(Sorry, that's a lot of questions and I know a lot of this is in the old thread, but a summary of it all in hindsight would maybe give me some additional pointers.)

To anyone else that uses an L2M, which tubes do you have in it and what are your observations on the stock tubes (or your replacement tubes if you did replace them)?

[Riccardo]

Hi Robin,
mine came with 12AX7LPS (Sovtek).
At the moment I have 4 x Brimar CV4004 (ECC83, RAF NOS) and a pair of Brimar 12BH7. I picked the Brimars by pure coincidence rather than specific choice.
Yes the change is not subtle at all. Depth of field is greater and as a consequence the sound is more three-dimensional. The change is more than welcome when I get good to very good mixes to work on. With lesser mixes the sovteks would probably be a better choice. They do not "blossom" as the Brimar do but and the same time don't exacerbate problems like sibilance for example.


YMMV

[24-96 Mastering]

Thanks Riccardo,

that's really interesting for me. Apologies if at any point I seem to be talking dumb... I know pretty much nothing about tubes, I'm very much a user only.

My observation with the stock Sovteks is that the character of the tube comes as softening of the highs (which is great for sharp highs in mixes, not great for tracks where the highs sound nice.)
Also, there's a bump / a change in character in the fundamentals area (probably most between 250 and 400 Hz or so) that is great for some stuff, but not so nice for most. This comes in pretty strong with feedback. Also, it seems to slightly narrow the stereo image.
This is all reasonably subtle when used clean (although already enough to be used as a subtle softening effect) but becomes quite strong when using feedback. Even when I want exactly that character, dialing in the smallest amount (1 dB) often gives me more than I want.

So... I'm thinking different tubes may have a character that is more up my street - or is a little more subtle so I can dose it better with the feedback. I do want to be able to dial in character; I don't want the box to serve just as a clean level rider.

Ricardo, would you say that you can relate to what I'm writing, that the Brimars might take care of what I don't like while providing some balls when used with feedback?

(I'm also happy for any other tube ideas anyone might have.)

[Riccardo]

Robin,
I am using the Brimars just because I wanted to try NOS tubes and found those (just before prices for CV4004 went through the roof).
Other tubes to consider are RCA 12BH7 (black plates probably better than grey ones) as well as Sylvanias.

ECC83 well ... again Sylvanias, Siemens /Halske, Mullards, Telefunkens, RFT .......

Yes if you want it to be a little less neutral and are happy with character and three-dimensional (added) sound stage go for it.

Not really sure when you are referring to feedback. What version of the Requisite are you using?

[24-96 Mastering]

Thanks; I guess I should dive into the market and see what's available and how much that would be. Do you or anyone else have any suggestions where to buy / where to get quotes from?

Originally Posted by Riccardo

Not really sure when you are referring to feedback. What version of the Requisite are you using?

mk3

[DSD_Mastering]

I get all my tubes from: Upscale Audio


Regards,

[lucey]

Nice NOS tubes like Brimars, Amperex Bugle Boy, GE black plates or many others from the 50s and 60s will open it up a bit, and more musically, than Sovteks. I also went to the 12BH7 in one position, as I was looking to thin the 100-200 range and Danny suggested those (GE black plates). Sylvania is the most neutral to my ear, boring if you will, but good to hold tone (eq and color) where it is.

Brendan at Tube World is a good source. Like Upscale he's frustratingly expensive, but assured to be well matched, quiet and as advertised.

[24-96 Mastering]

Thanks.

I'm lost...

I have many, many questions:

- Should I go for "best pair"? How can one justify not going for best pair? (argh)
- I assume I want platinum grade low noise - simply because the words sounds good. Is there anything I should know about it?
- frozen tubes???? really? snake oil or actual improvement?
- The variation in price is enormous between different places as well as different tubes. I understand finding and collecting tubes followed by careful matching has its price, I just want to be sure that Tube World is not an esotheric place / that it's not a rip of / that there aren't any other places with NOS tubes matched just as well for a more down to earth price.
- Am I right to assume that, should I not like the couple of well matched NOS tubes I buy and try, their resale value will be much lower than what I bought them for (maybe even less than 50% of the price)? Asking this so I know how much I'm spending to evaluate them.
- From what I'm reading, all different makes sound great. On the Tube World web site they have comparative descriptions that, of course, don't really help me, because they are only listing positive attributes... Anyway, thanks for the pointers from everyone so far. If anyone can provide any additional opinions on which NOS tube models tend to sound how and how much so, please don't hold back.

[lucey]

It's very hard to talk about tubes as semantics and at times opinions differ somewhat. Then someone shows up and says they're not important, and only circuits matter!

There's a chart on the Tube World page for 12AX7s that's pretty good.

[24-96 Mastering]

Sorry to continue coming back to this. There's another thing I wonder.

How much of a difference will the non-audio path 12AX7 tubes (i.e. the tubes that drive the compression amp) make?

[Silvertone]

Some of the tubes are just for power and have nothing to do with the sound. So I wouldn't even bother replacing them.

Only buy NOS tube from a reputable dealer otherwise you are taking a real chance.

[24-96 Mastering]

Thanks for all the replies and links. They were very helpful and are very much appreciated.

FYI, I have just ordered a pair of MAZDA chrome plates NOS to replace the 12AX7LPS in the signal path and a pair of Sylvana 12BH7 to replace the 6414 output driver tubes (both ordered from Upscale Audio).

The Mazdas are french military, ca. 1960-1963 and are supposed to be pretty clean and... for lack of a better word... lively. I chose them over the tubes that Danny suggested (Mullard) because those - as far as I have been told - have a silky, in tendency soft&warm sound and that quality is, to some extent, already covered by my modded Vari-MU. I'm writing this purely relying on information from others, so as of yet, I have no idea if this thinking makes any sense in reality.
But who knows, maybe I'll get a couple of pairs to be used in different situations.

I'll write how they fare in a couple of days, when I get back in the studio (on vacation right now).

PS: does anyone know a trustworthy place to buy well matched NOS tubes in Europe?

[24-96 Mastering]

A quick update, in case someone's interested:

The NOS tubes do indeed make a very significant difference. The Mazda/Sylvana combo I put in are definitely cleaner in the highs than they Sovteks and the 300-400Hz bump that bugged me before is gone.
The negative feedback is now more subtle and its character - imo - much more desirable. The feedback dial now feels usable.

I still don't know how much difference there is between different NOS tubes though... but for cost reasons, I don't feel too compelled to buy/try different flavours of 12AX7s.
But if anyone passes by Karlsruhe and happens to have some nice tubes with them, let me know, I'll fix some coffee

[macc]

I'm interested... how much were they? Happy with this Upscale audio place then?

That 3-400Hz bump is starting to bug me in my Avalon (same Sovteks I think), your bump of this couldn't have been timed better

EDIT: Sorry, should have googled first; these ones? Mazda Chrome Plate 12AX7

[24-96 Mastering]

Originally Posted by macc

I'm interested... how much were they? Happy with this Upscale audio place then?

That 3-400Hz bump is starting to bug me in my Avalon (same Sovteks I think), your bump of this couldn't have been timed better

EDIT: Sorry, should have googled first; these ones? Mazda Chrome Plate 12AX7

Yep, those are the ones I got. I paid 180 for the pair of 12AX7s and 40 or so each for the Sylvana 12BH7. Upscale Audio were nice to deal with and the pairs they sent were very well matched (my ears and meters have no objections). However, they don't take international credit cards... And I thought all credit cards were international - I thought that was the point of credit cards - accepted everywhere. Oh well, what do I know.

It seems quite possible that bump is caused by the Sovteks in your Avalon 747. I read it's 6922, not 12AX7 tubes though. Maybe ask other 747 users if replacement with NOS tubes made the desired impact on the sound before spending cash (sorry if that's an obvious point).

[lucey]

The fact that you have quality NOS tubes in there is the main thing. The differences in NOS tubes are real but you've done all that needs to be done IMO. In my Fairman EQ I have used different brands in each band for their sympathetic qualities per band (Tele for high shelf, Mullard for high mids, RCA black plate for low mids, Amperex for output gain, etc) but this REALLY being nutty about it in a 22 tube unit where that kind of OCD matters more. Just getting rid of the the russian tubes is still the main upgrade to musicality and clarity.

[macc]

Originally Posted by 24-96 Mastering

It seems quite possible that bump is caused by the Sovteks in your Avalon 747. I read it's 6922, not 12AX7 tubes though. Maybe ask other 747 users if replacement with NOS tubes made the desired impact on the sound before spending cash (sorry if that's an obvious point).

There was a thread on here not long ago where someone indicated that, but I found this thread interesting as you mentioned a similar thing - and also a supplier

And yeah, you're right it is 6922.. I just thought perhaps it might be a 'Sovtek house sound' thing, as it were. I definitely hear it though and I'm starting to have had enough with it...