Question to owners of ARC Reference Anniversary and/or Reference 10 preamp

ayreman

New Member
Jan 2, 2017
72
0
0
Ukraine
#1
ARC Ref Anniversary preamp and Reference 10 come with a pair of Sovtek 6550 tubes in the PS. Did anyone experiment with these tubes trying to use alternatives such as KT88, KT90, KT120 or even KT150? Ever since I bought my Ref Ann I never bothered trying anything different other than the Sovtek 6550. Does anyone want to share their experiences? Did anyone switch the Sovtek 6550 for a better alternative and stuck to it?
 
May 30, 2010
13,912
5
38
Portugal
#2
ARC Ref Anniversary preamp and Reference 10 come with a pair of Sovtek 6550 tubes in the PS. Did anyone experiment with these tubes trying to use alternatives such as KT88, KT90, KT120 or even KT150? Ever since I bought my Ref Ann I never bothered trying anything different other than the Sovtek 6550. Does anyone want to share their experiences? Did anyone switch the Sovtek 6550 for a better alternative and stuck to it?
DO NOT USE KT type tubes in the power supply of ARC equipment unless you confirm directly with the factory. The tube is used as series pass element and during warm up this circuit can exceed the maximum voltage ratings of the KT's. It is why ARC are using 6550's in this position. Unfortunately the only alternative are NOS 6550 that are now expensive.
 

ayreman

New Member
Jan 2, 2017
72
0
0
Ukraine
#3
DO NOT USE KT type tubes in the power supply of ARC equipment unless you confirm directly with the factory. The tube is used as series pass element and during warm up this circuit can exceed the maximum voltage ratings of the KT's. It is why ARC are using 6550's in this position. Unfortunately the only alternative are NOS 6550 that are now expensive.
Ok, that's important to know. What that also does is it limits the circle of contestants to various makers of 6550 out there. Is there an undisputed leader out there that would put Sovtek 6550s to shame?;)
 
May 30, 2010
13,912
5
38
Portugal
#4
Ok, that's important to know. What that also does is it limits the circle of contestants to various makers of 6550 out there. Is there an undisputed leader out there that would put Sovtek 6550s to shame?;)
Many people praise the NOS GE highly. IMHO for this application low noise should be the key point - I still have not prepared my tube tester to check for noise in power tubes.
 
Jul 9, 2011
817
0
0
Chicago, IL
#5
Many people praise the NOS GE highly. IMHO for this application low noise should be the key point - I still have not prepared my tube tester to check for noise in power tubes.
I use the NOS GE in both my Ref10 preamp and Ref10 phono with very noticeable improvements in clarity and soundstage.
 

ayreman

New Member
Jan 2, 2017
72
0
0
Ukraine
#6
So no one even used KT90 in the PS?
 
May 30, 2010
13,912
5
38
Portugal
#7
So no one even used KT90 in the PS?
If people care to read the specifications of the KT90 - 1st grid negative voltage (max) - 200V they will not even think about it ...
 
Oct 30, 2017
496
0
16
USA
#8
Ayreman, If you don't mind me asking a related tag along question to the thread, I would love to know if anyone is buying NOS 6550's that have gone through the rigorous testing, matching and pre-biasing that ARC performs prior to sale. If so what resellers do such testing (on the GE's in particular)? I have been too cautious given the content of the following ARC piece to try the aftermarket but am intrigued.

View attachment Why buy vacuum tubes from Audio Research.pdf
 
Jun 18, 2011
738
5
18
Hong Kong
#9
ARC Ref Anniversary preamp and Reference 10 come with a pair of Sovtek 6550 tubes in the PS. Did anyone experiment with these tubes trying to use alternatives such as KT88, KT90, KT120 or even KT150? Ever since I bought my Ref Ann I never bothered trying anything different other than the Sovtek 6550. Does anyone want to share their experiences? Did anyone switch the Sovtek 6550 for a better alternative and stuck to it?
I own an ARC 40th Anni Preamp and two friends of mine own the ARC Ref 10 preamps.
We tested diff contemporary and NOS tubes on our preamps and all of us think that the NOS tubes are the best performers.
The very best replacement for the original 6550 is definitely the Tung-sol black-plate made in 1950s.
The second best is the Tung-sol grey-plate made in 1960s.
We also bought and tried the popular NOS Winged-C 6550 but found that it was far inferior to the above two tubes.
The 6550 supplied by ARC may have been burned-in/tested/matched so they are reliable but sonics-wise they are many leagues below.

The problem is that ARC40 & Ref10 both need a pair of 6550 and the black or grey plate are quite rare. It's not easy to find a matched pair of good quality so we stock up spare pairs.
 
Oct 30, 2017
496
0
16
USA
#10
I own an ARC 40th Anni Preamp and two friends of mine own the ARC Ref 10 preamps.
We tested diff contemporary and NOS tubes on our preamps and all of us think that the NOS tubes are the best performers.
The very best replacement for the original 6550 is definitely the Tung-sol black-plate made in 1950s.
The second best is the Tung-sol grey-plate made in 1960s.
We also bought and tried the popular NOS Winged-C 6550 but found that it was far inferior to the above two tubes.
The 6550 supplied by ARC may have been burned-in/tested/matched so they are reliable but sonics-wise they are many leagues below.

The problem is that ARC40 & Ref10 both need a pair of 6550 and the black or grey plate are quite rare. It's not easy to find a matched pair of good quality so we stock up spare pairs.
Thanks. Very helpful. So the only practical approach is to find the blacks and greys and check them yourself? Do you test the tubes yourself or do the matching by ear?
 
Jun 18, 2011
738
5
18
Hong Kong
#11
Thanks. Very helpful. So the only practical approach is to find the blacks and greys and check them yourself? Do you test the tubes yourself or do the matching by ear?
One of us has a simple tube-tester but we are not tech-guys.
We bought pairs from shops, mostly online bcos these tubes are rare in Hong Kong.
Have to take some risk.
 
May 30, 2010
13,912
5
38
Portugal
#12
One of us has a simple tube-tester but we are not tech-guys.
We bought pairs from shops, mostly online bcos these tubes are rare in Hong Kong.
Have to take some risk.
For power supplies the matching is not as critical as in power sections - the 6550 tube is used as a series regulator and the control circuit can compensate for reasonable variations of Vg. IMHO burn-in is mandatory - preferably carried in a jig or in a cheap amplifier with a fused B+ supply, do not risk your ARC preamplifier with untested new tubes. You should measure the tube before burn-in and after 100 hours.
 
May 30, 2010
13,912
5
38
Portugal
#13
I own an ARC 40th Anni Preamp and two friends of mine own the ARC Ref 10 preamps.
We tested diff contemporary and NOS tubes on our preamps and all of us think that the NOS tubes are the best performers.
The very best replacement for the original 6550 is definitely the Tung-sol black-plate made in 1950s.
The second best is the Tung-sol grey-plate made in 1960s.
We also bought and tried the popular NOS Winged-C 6550 but found that it was far inferior to the above two tubes.
The 6550 supplied by ARC may have been burned-in/tested/matched so they are reliable but sonics-wise they are many leagues below.

The problem is that ARC40 & Ref10 both need a pair of 6550 and the black or grey plate are quite rare. It's not easy to find a matched pair of good quality so we stock up spare pairs.
Did you test the JJ 6550 tube from Slovakia?
 
Oct 30, 2017
496
0
16
USA
#14
For power supplies the matching is not as critical as in power sections - the 6550 tube is used as a series regulator and the control circuit can compensate for reasonable variations of Vg. IMHO burn-in is mandatory - preferably carried in a jig or in a cheap amplifier with a fused B+ supply, do not risk your ARC preamplifier with untested new tubes. You should measure the tube before burn-in and after 100 hours.
Good stuff. Thx. Any recommended turn key sellers providing this service on the better NOS tubes (besides ARC)?
 

tdh888

New Member
Nov 5, 2010
254
0
0
Philippines
#15
Good stuff. Thx. Any recommended turn key sellers providing this service on the better NOS tubes (besides ARC)?
Try Jim McShane , check out his website , very helpful and knowledgeable. Ordered a lot of tubes from him for myself and my friends . His tubes are well tested and his testing & matching I might say is at par w/ ARC . His based in Chicago .

Hope this helps,

Tdh888
 
Oct 30, 2017
496
0
16
USA
#16
Try Jim McShane , check out his website , very helpful and knowledgeable. Ordered a lot of tubes from him for myself and my friends . His tubes are well tested and his testing & matching I might say is at par w/ ARC . His based in Chicago .

Hope this helps,

Tdh888
Thanks much for the help. I will check him out.