6C45P availability question

[Loquah]

I discovered yesterday that the 6C45P isn't a production tube any more - I had thought it was!?

During my discussion with the fellow audio enthusiast, he mentioned that there are some cryo treated gold-pin varieties out there that are getting harder to find so I'm wondering: is it worth tracking down a few sets of 6C45P to put on the shelf now or are there factories full of these things around the world?

Also, would "upgraded" versions of these tubes bring benefits to the Mainline or is it's design such that tubes don't have significant impact?

[swich401]

Where did you hear that the 6C45Pi was out of production? I thought Sovtek (New Sensor) was still manufacturing new tubes?

I'm thinking of picking up a set of Electro-Harmonix and Sovtek's from here:
http://www.wooaudio.com/products/wa7fireflies.html

[Loquah]

A fellow enthusiast who owns the Woo WA7 and a set of their upgrade 6C45Pi-EHG cryo treated tubes. I think he's a reliable source...

[swich401]

Hmm, too bad, I'll have to pick up a couple pairs to make sure I don't end up scrounging for some a couple years down the road.

[Grainger49]

They are available as NOS Surplus Military tubes.  I expect there are cases, or crates of them available. 

[Loquah]

I hope so.

I don't plan to rush into modifying the circuit, but are there any other tubes that the Mainline would work with effectively with some minor alterations?

[Paul Birkeland]

New Sensor has made new 6C45's, but I don't believe they were particularly successful in their efforts. 

For the time being, there aren't other triodes that will drop into the circuit, except perhaps with WE 437A.

The military surplus supply of 6C45's appears to be very significant.  When they begin to dry up, the Chinese and Russians will put them back into production, and eventually get the bugs worked out.

[swich401]

I ordered a pair of Electro Harmonix 6C45's. I'm planning to do a complete review of the Mainline. Will compare single ended vs. balanced operation, and I'll compare the Sovtek tubes vs. the EH tubes as well, all using HD800's. Now just to wait until my kit arrives... 

The following site has some interesting things to say about the EH 6C45's, but they are doing the comparison in the WA7 fireflies:

http://www.audio360.org/amps-dacs_a0018_review_woo_audio_wa7_fireflies.php

[Paul Birkeland]

To properly make the 6C45PI, the grid wires need to be at least platinum plated wire, if not solid platinum. 

In combination with this materials issue, the tube itself is very difficult to produce, and hence the EH's are out of production.  One would hope that they are continuing research on other production methods to "get it right".

[Loquah]

I was able to pick up a well priced matched pair of Electro Harmonix gold pin 6C45Ps today and I'm wondering if they will should be expected to improve the Mainline's sound at all?

They're widely considered a better example of the 6C45P models, but knowing how tightly controlled the performance of the Mainline is, I'm wondering if they'll make much difference. It's really hard to A/B them so any differences I'm hearing might be pure bias.

[swich401]

Would anybody happen to know how I could match tubes using the Mainline's circuits (I.e. try putting tubes one after another into the tube sockets and measure something when the amp is on)?? I'm hoping that there may be some way using a digital multimeter.

[fullheadofnothing]

Biasing instructions are in the manual.

[Loquah]

Biasing instructions are in the manual.

So does biasing essentially remove the need to have matched tubes?

[Paul Birkeland]

So does biasing essentially remove the need to have matched tubes?

The circuit design essentially removes the need to have matched tubes.

[Loquah]

Nice!

Am I correct then in thinking that if we change tubes we should redo the biasing?