ARC ref10 tube rolling?

[yuhengdu]

I just purchased a Ref 10 which shows 2535 on the tube hours. The preamp is on the way to arrive next week. I want to know what are the recommendations for some tube rollings for the ref 10?

It uses eight 6H30P in the main units, two 6550C and two 6H30P in the power supply. Thanks!

 

[tima]

The Ref 10 and Ref 10 Phono of mid and recent vintage use the Sovtek 6550WE. This tube is reliable, pretty straightforward sonics and available on today's market.

The two Ref 10 units originally came with and were voiced with the SED Winged-C 6550C. ARC discontinued using those because they went out of production. They are no longer readily available but you still will find them on offer occasionally. I've used both ARC units for a while now and imo the SED Winged-C 6550C is the best sounding tube for those components.

You will likely hear from people telling you to try various other 6550s, such as the GE 6550A or Tungsol 6550. The Tungsol are modern reissues and not equivalent to the nearly unobtanium Tungsol Black Plates of yore The GE 6550A worked fine in Conrad-Johnson amplifiers but is too warm and soft for the Audio Research gear and ARC doesn't like seeing that tube in their linestages because they believe it degrades the sound. I would stick with the 6550WE. Use matched pairs in the power supply.

The 6H30P that comes with the Ref 10s is the Sovtek 6H30P. The 'Gold' Electro-Harmoix version is a relabeled Sovtek with gold (colored?) pins. I'm not a fan of E-H tubes as I find them inconsistent in quality, but in principle you'll get the same result from E-H as Sovtek.

For some time now there is on-going talk of the 6H30DR which was the ruggedized military version of the tube and popularized by Viktor Khomenko for use in his BAT electronics. As far as I know all 6H30s come out of the same factory in Russia.

At one time the 6H30DR was available and relatively inexpensive. Many people found it to have slightly superior sonics. The last of the DR were brought from Russia to No.America a few years back by Eugene Conus of Conus Audio. They are no longer available from tube stores but individuals occasionally may have some on offer. The early price was $15-$35 and now they are closer to $300 each. I've used full sets of these in both my Ref 10s and thought they gave some small improvement, but at current prices (if you can find 9 of them) the value, imo, is not there. You should know there are numerous counterfeit 6H30DRs on the market. Check this article on how to tell originals.

My suggestion is first to enjoy the sound of the Ref 10 with stock tubes before trying alternatives. Acquire a set of stock tubes as a backup.

 

[hi5harry]

In my Anni 40 I found a slight improvement with the DR 6h30's and a slight improvement with the GE 6550's, but a very worthwhile improvement with the old TungSol 6550's.

 

[yuhengdu]

The Ref 10 and Ref 10 Phono of mid and recent vintage use the Sovtek 6550WE. This tube is reliable, pretty straightforward sonics and available on today's market.

The two Ref 10 units originally came with and were voiced with the SED Winged-C 6550C. ARC discontinued using those because they went out of production. They are no longer readily available but you still will find them on offer occasionally. I've used both ARC units for a while now and imo the SED Winged-C 6550C is the best sounding tube for those components.

You will likely hear from people telling you to try various other 6550s, such as the GE 6550A or Tungsol 6550. The Tungsol are modern reissues and not equivalent to the nearly unobtanium Tungsol Black Plates of yore The GE 6550A worked fine in Conrad-Johnson amplifiers but is too warm and soft for the Audio Research gear and ARC doesn't like seeing that tube in their linestages because they believe it degrades the sound. I would stick with the 6550WE. Use matched pairs in the power supply.

The 6H30P that comes with the Ref 10s is the Sovtek 6H30P. The 'Gold' Electro-Harmoix version is a relabeled Sovtek with gold (colored?) pins. I'm not a fan of E-H tubes as I find them inconsistent in quality, but in principle you'll get the same result from E-H as Sovtek.

For some time now there is on-going talk of the 6H30DR which was the ruggedized military version of the tube and popularized by Viktor Khomenko for use in his BAT electronics. As far as I know all 6H30s come out of the same factory in Russia.

At one time the 6H30DR was available and relatively inexpensive. Many people found it to have slightly superior sonics. The last of the DR were brought from Russia to No.America a few years back by Eugene Conus of Conus Audio. They are no longer available from tube stores but individuals occasionally may have some on offer. The early price was $15-$35 and now they are closer to $300 each. I've used full sets of these in both my Ref 10s and thought they gave some small improvement, but at current prices (if you can find 9 of them) the value, imo, is not there. You should know there are numerous counterfeit 6H30DRs on the market. Check this article on how to tell originals.

My suggestion is first to enjoy the sound of the Ref 10 with stock tubes before trying alternatives. Acquire a set of stock tubes as a backup.

Hey tima, thanks for the detailed reply. This is tremendously helpful!
As for the Tungsol black plates 6550s, how can I tell the reissues from originals? I found a couple of pairs for sale at ebay: https://www.ebay.com/itm/133604886140, https://www.ebay.com/itm/373395821811 but not sure which year are they made?

The SED 6550C seems to be an easier find that also cheaper: https://www.ebay.com/itm/382509856691. Thanks for the suggestion!
Also found some 6h30dr that seems to avoid the check boxes of counterfeit https://www.ebay.com/itm/324399938541. If I ever want to try them, should I start with the pair in power unit? Thanks!

 

[yuhengdu]

In my Anni 40 I found a slight improvement with the DR 6h30's and a slight improvement with the GE 6550's, but a very worthwhile improvement with the old TungSol 6550's.

Thanks. Which version of Tungsol 6550s were you using? Do you have a recommendation of trustworthy sources to get them?

 

[hi5harry]

I am using the grey plate, 3 hole TungSol 6550's. I understand the black plate, 3 hole are quite a bit better, but I am using NOS tubes I have had for many years. I don't have a great source for any NOS tubes other than trusted friends. Even the GE 6550's would be a nice find. They seem to last for a very long time. Enjoy that fantastic Ref 10 pre. It's a phenomenal pre!

 

[microstrip]

I just purchased a Ref 10 which shows 2535 on the tube hours. The preamp is on the way to arrive next week. I want to know what are the recommendations for some tube rollings for the ref 10?

It uses eight 6H30P in the main units, two 6550C and two 6H30P in the power supply. Thanks!

Remember that the 6550C should be replaced every 2000 hours, but the 6H30p's should only be replaced every 4000 hours - this means that you still have a longtime before having to change them.

The most important aspects in the 6H30's is triode matching in each tube and noise. A good 6h30 tube lasts for long, but we should always keep a spare pair!

 

[CKKeung]

I had a 40th Anniv for nearly 8 yrs before going the passive preamp route.

I did much tube-rolling with TLi, a WBF member in HK who owned a Ref10.
Genuine 6H30DR is good but they are now nearly usd400 per piece.
Expensive and difficult to find so many matched pairs for Ref10 or 40Anniv.
I don't think it's worthwhile.

On the other hand, upgrading the 6550 is much more rewarding.
1950s Black-Plate is the best but 1960s Grey-plate is also very good.
The newer NOS SED6550C is behind the above NOS but still better than the current 6550.
The 6550 in Ref10 or 40Anniv need more frequent replacement than the 6H30. It will be perfect if you can monitor their health with a tube tester.

 

[tima]

As for the Tungsol black plates 6550s, how can I tell the reissues from originals?

 

[Golum]

As I did it in my ex-Ref6 I would suggest you to roll 6n30 with 6n6p which are cheap and really do make significant difference - you have experiences described in Ref6 tube rolling thread. Also SQ diff might very well be much bigger then playing just with 6550 (my case)...

 

[yuhengdu]

As I did it in my ex-Ref6 I would suggest you to roll 6n30 with 6n6p which are cheap and really do make significant difference - you have experiences described in Ref6 tube rolling thread. Also SQ diff might very well be much bigger then playing just with 6550 (my case)...

Thanks for the advice! Do you happened to tried a few different brands of 6n6ps? And should I replace all 8 of them in the main unit and 2 of them in the power unit, or is there a recommended place where to put them first? Thanks!

 

[Golum]

Thanks for the advice! Do you happened to tried a few different brands of 6n6ps? And should I replace all 8 of them in the main unit and 2 of them in the power unit, or is there a recommended place where to put them first? Thanks!

You're welcome! There are no two diff brands as those are USSR production so getting matched pairs from '60'70's is the best. Also you might want to chase the ones with silver screen as apparently those ones were the "ones". I had normal and the ones with silver screen and both performed exceptional.
Go for 8 pcs in line stage as the change is most profound when you swap these - at least that's what i did and later i replaced also one near the 6550.

 

[microstrip]

The 6n6p is pin compatible with the 6H30, but has very different parameters - it is a completely different tube. Most circuits designed for a 6h30 will operate with a 6n6p, but we get a different sounding preamplifier - the operating points move significantly.

 

[yuhengdu]

You're welcome! There are no two diff brands as those are USSR production so getting matched pairs from '60'70's is the best. Also you might want to chase the ones with silver screen as apparently those ones were the "ones". I had normal and the ones with silver screen and both performed exceptional.
Go for 8 pcs in line stage as the change is most profound when you swap these - at least that's what i did and later i replaced also one near the 6550.

Got it! Thanks for letting me know.

 

[yuhengdu]

The 6n6p is pin compatible with the 6H30, but has very different parameters - it is a completely different tube. Most circuits designed for a 6h30 will operate with a 6n6p, but we get a different sounding preamplifier - the operating points move significantly.

Will that affect the functionality or life span of the preamp?

 

[microstrip]

Will that affect the functionality or life span of the preamp?

Can't be 100% sure, as I have not measured the voltages inside the unit with the 6n6p, but I think it will be harmless - I am assuming the tube pin thickness are also the same of the 6h30. Some russian alternative tubes have thicker pins that will enlarge the socket contacts.

 

[microstrip]

I have often posted that I had found that the 6H30 for Audio Research Anniversary REF10 and similar series need to be matched for plate current for both triodes inside the tube as they are operated in parallel. If unmatched one triode starts progressively carrying more current than the other, heats and becomes noisy - I found that 6h30 tubes that become noisy were usually unmatched. Just read the confirmation in a post in the AudioAficionado forum https://www.audioaficionado.org/showpost.php?p=1027435&postcount=10

This is what ARC says about tube matching in the REF 5SE:

"The 6H30's do not need to be matched like they do in the power amps but you do want to make sure they are well balanced on each part of the triode."

The 6H30 is a dual triode, so I presume the balance that they refer to is the matching of each triode within the individual 6H30.