ARC Ref 3: Tung-Sol 6550 in power supply?

i didn't ask re PC's

Jmcgrogan2 did.

I have a pair of NOS TungSol 6550 Black Plates (solid) from the early 50s - I will try them and will report back. I'm aslo burning in a quartet of NOS 6H30DR tubes.

Guidocorona - Which Tung Sol 6550 have you tried ? The original NOS Black Plate from the 50s that or the current "Tung Sol 6550 reissue" ?

Posbwp555 - I think that the problem with Ref 3 - and all other components build around 6H30 tube for that matter - is the range of available alternatives is extremly limited. AFAIK there is only one NOS tube you can try - the mil spec 6H30 DR tube from the late 80s/early 90s.

There is a wider selection of NOS 6550s - you can get TungSol, GE - but that tube (single) is only used in Ref 3 power supply, so its impact may be somehow limited.

Yesterday, I have played with the quartet of DRs in my Ref 110 power amp. They improved HF extension, soundstage depth and allowed to hear more of the spatial clues. The improvement was not dramatic by any means - more like power cord upgrade, but it was worthwile nonetheless and I'm looking forward to try them in my Ref 3 as well (hopefully today).

OK guys, I have already installed NOS Tung Sol in the PS of my Ref 3. Now I'm wondering, how much time I should allow for burn-in (this is a brand new tube) ?

First listening tests with NOS Tung Sol 6550 Black Plate on board are very encouraging. After 10h of break in, I'm confident to say that my system never sounded better in the following areas:

1. Purity of tone
2. Resolution
3. HF extension and air
4. HF clarity and purity
5. Soundstage depth and image bloom
6. Musiacal Flow

Supprisingly, changes are rather dramatic and similar in character to an interconnect or a speaker cable change - unlike substituting 6H30 tubes with their DR alternatives, which brought only minor improvements (so far, I have only tried DR tubes in my Ref 110 power amp, but my guess is that the effect will be similar in Ref 3).

This is the best $400 I have spent on my system in a long time. I cannot recommend this change highly enough. If you really haven't heard the Ref 3 with a NOS 6550 tube on board - then you haven't heard what Ref 3 can do.

Jmcgrogan2 ->

ARC uses Shunyata Anaconda Helix Alpha PCs at their factory.

Oneobgyn ->

99% of manufacturers stick to current production tubes. So even though, SED 6550 that is used in all ARC gear may well be the best current production tube available, there is also a broad selection of NOS tubes (various TungSol, GE), which very often, are far superior.

BTW - for those who wish to stick with current production tubes - there is a more expensive version of SED 6550, called Black Sable. It is made by the same manufacturer, but is twice as expensive. I was always wondering, what difference it may make.

Marco_esposito - what TungSol 6550 tube did you try ?

NOS Black Plate/Gray Plate from the 50s-60s or the new production TungSol "reissue" ?

I'm asking this question since those are two very different tubes.

Marco_esposito - your findings seem to confirm what Guido has written before - the current production TungSol 6550 (so called "reissue") does not bring a net benefit compared to SED 6550C.

When I was talking about the improvment I got by inserting a TungSol 6550, I meant the NOS (New Old Stock) TungSol 6550 Black Plate from the early 50s - which is a totally different tube to the one you have tried.

I cannot recomment it (NOS TungSol Black Plate) highly enough.

I have been using the NOS 6550 TungSol Black Plate without any single issue for the past 6 months or so, and so do my two friends.

My guess is that the problem is not 6550 related.

I'm affraid you are getting what you have paid for.