tuberolling the REF5SE

[dminches]

Originally Posted by soundslikemusic

these ?

PR Vintage Tungsol 6550s Black Plates 3 D Getters Matched 1958 USA EX Sound | eBay

Very similar, yes.

[max17]

Is there any bias adjustment required when changing out the 6550 tube in the Ref5SE? Any time a power tube is changed in an amp the new tube needs to be biased but I never heard of this being necessary, or possible in a pre-amp.

[soundslikemusic]

Originally Posted by max17

Is there any bias adjustment required when changing out the 6550 tube in the Ref5SE? Any time a power tube is changed in an amp the new tube needs to be biased but I never heard of this being necessary, or possible in a pre-amp.

For pre-amps, i havent seen that bias adjustment like the tube power amp.

i just swapped the 6550 in my REF5se and i dont see any adjustments inside the chassis.

[max17]

Thanks for the info.

[ariess]

Has anyone tried a 6550 Winged C in their Reference 10 and can share the experience? Upgrade in sound? Source of tubes? Issues?

[sander]

Originally Posted by Formerly YB-2

And I was wondering if I was over-doing-it with three (3) quads (2x 6550 & 1x KT-88). I've been pleased with my dealings with the folks at Up-Scale audio. I would not hesitate to purchase tubes from them if they have a better $$ then some of the other resellers.

Up-Scale audio also performs Cryogenically treatments on their tubes.

Do you or anybody else on the forum here has first hands experience with these Cryogenically treated tubes?

[Harlequin]

Originally Posted by jamnesta

Tima, In the comments section after Stereophile's review of the Ref 5SE someone asked about the possibility of rolling in a KT88. JA's reply follows;
"These tubes are very similar and used as the series-pass element in the voltage regulator, I don't expect them to behave differently. However, I wouldn't do so until you have checked with Audio Research."

John Atkinson

Editor, Stereophile

I wonder, with the great current production KT88's available; Gold Lion, Shuguang Treasures, Penta Labs, Psvanes, etc it seems this would be worth exploring as 6550's don't seem to have the same interest of the tube manufacturers.

My initial enquiries with the Death Star met with the standard polit bureau response,

"ARC would not support or recommend the substitution of the stock 6550 with any KT88 tube"

However whilst on the telephone I managed to extract, through Gritted teeth, disclosure that there 'should' not be any circuit requirement that would preclude the use of an KT88 for power regulation duties within my, then, incumbent REf5SE.

However, In the end I did not perform such a substation as without an example to hand I began to have my doubts that the extra girth of the KT88's glass envelope would prevent its operationally and physically safe insertion due to the extremely close proximity of the associated 6n30, even with its anti resonance rings removed.

[Tomictime]

Just replaced the factory 6550 with another from ARC @ 2,300 hours. $100. maybe roll the dice next time.

What are people doing w small signal tubes ? I am running Amperex and RCA in the DAC but have not tackled the Pre..yet...