Telefunken RS237

[Zero000]

Big smiles.

Alternative? Seriously? For 3.5K (it is less in pounds for Tom's valves more like £3K) I'd go buy a decent solid state amp from eBay and switch between the 211s and the solid state option every few months.

Variety is the spice of life.

 

[spiritofmusic]

Maybe not.

 

[bonzo75]

Also, if you are worried about bias, you can almost certainly do it yourself.

He does bias himself, quite often.

 

[bonzo75]

What I mean is, I keep hearing that amp designers "voice" their creations around their tube of choice
...Kondo and Nat around the GE 211
...Mayer around the Mayer Elrog 211/242
...AN around the AN 4242

No matter what sofa you buy at what price, you can top up with up with superior quality cushions, or even whole upholstery.

 

[DasguteOhr]

I'll bear him in mind.
Is it really necessary to have a matched quad? I'd say that's practically impossible with the likes of these Telefunkens and Amperex etc, unless you died and went to heaven.
Are matched pairs "good enough"?
And are these Telefunkens good for any 211 amps out there? Mechanically and electrically consistent for all amps using 211 tubes?

No, with push pull amps it is more important that the positive half-wave is amplified the same as the negative half-wave, otherwise you will get inharmonic distortions. What's more important is the same steepness (S value mA/V )for your amp, anything less than 10% difference is almost perfect.
Exsample
Tube 1 = 61mA, S = 3,75mA/V
Tube 2 = 61mA, S = 3,62mA/V

 

[spiritofmusic]

No, with push pull amps it is more important that the positive half-wave is amplified the same as the negative half-wave, otherwise you will get inharmonic distortions. What's more important is the same steepness (S value mA/V )for your amp, anything less than 10% difference is almost perfect.
Exsample
Tube 1 = 61mA, S = 3,75mA/V
Tube 2 = 61mA, S = 3,62mA/V

Sure, so can one really trust eBay online vendors who claim such correlations?
We're not taking cheap signal tubes from Ukraine as I used to try on my preamp a few years ago.
A pair of *so-called* balanced Amperex, UE, Telefunkens is pushing £4-5k.
I'm assuming with the likes of Mayer and AN, the datasheets will be by definition reliable?

 

[spiritofmusic]

No matter what sofa you buy at what price, you can top up with up with superior quality cushions, or even whole upholstery.

Gosh, I really didn't know that Ked.
Can I mix stripes with floral designs?
How about colour combinations?
Please tell me more...

 

[DasguteOhr]

Sure, so can one really trust eBay online vendors who claim such correlations?
We're not taking cheap signal tubes from Ukraine as I used to try on my preamp a few years ago.
A pair of *so-called* balanced Amperex, UE, Telefunkens is pushing £4-5k.
I'm assuming with the likes of Mayer and AN, the datasheets will be by definition reliable?

Of course, with new goods there is always a guarantee and the values are recorded precisely. There is no guarantee with NOS tubes, and first of all, how are you supposed to get identical 80-year-old tubes again? If you want Nos tubes, there are only a few that can provide an adequate replacement in the event of a failure. BTB tubes can only recommend, fast shipping and no problems in the event of a warranty claim.
Here e.g nice 838 you can get easy 35 watt out of this tube

838 Power Triode Jumbo Uf=10V - BTB Elektronik

838 Power Triode Jumbo Uf=10V - Bajonett Jumbo 4-pin tube-valve-base

btb-elektronik.de

 

[spiritofmusic]

Of course, with new goods there is always a guarantee and the values are recorded precisely. There is no guarantee with NOS tubes, and first of all, how are you supposed to get identical 80-year-old tubes again? If you want Nos tubes, there are only a few that can provide an adequate replacement in the event of a failure. BTB tubes can only recommend, fast shipping and no problems in the event of a warranty claim.
Here e.g nice 838 you can get easy 35 watt out of this tube

838 Power Triode Jumbo Uf=10V - BTB Elektronik

838 Power Triode Jumbo Uf=10V - Bajonett Jumbo 4-pin tube-valve-base

btb-elektronik.de

My point was that your perfectly reasonable point about the pressing need for as much "matched" as possible is critical to prevent less than optimal function or malfunction, but it's harder and harder to find matched pairs with the likes of RCA, UE, Amperex, Telefunken, matched quads unobtanium. Even noticeable with GE.
My Q was more, is it ok to have one (as close to as possible) matched pair per monoblock, even if the values per matched pairs are quite different L and R?
I guess re-reading that, the values would only be the same R and L pairs is they were a matched quad.