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A question of bias for new tube set

Something seemed a bit off with my system so i checked the temperatures of the EL34 power tubes on my Cary Audio Six pacs with a pyrometer and found all the tubes reading a temperature around 360 deg F +/-  but one. The errant tube was reading around 175 deg F. Checked the bias on each mono block and found that the set with the errant tube was way off the recommended bias I usually set which is 220 ma. It read 180 ma. The other mono block was operating in spec. I also noticed that with a music source, the bias readings on both mono blocks seemed to swing 10 or so ma with the music. Didn't know if this was normal or not but figured since i had a bad tube and had no idea of the age of the tube set (bought the Six Pacs used), I figured it was time for a full set replacement.

The existing tubes were Svetlana Winged C EL 34s but after some research, I decided to buy a matched set of Electro-Harmonix EL34s from Kevin Deal of Upscale Audio. According to Kevin the EH tubes were less extended in the bottom end but added some sparkle to the upper range. Since they were about half the price of other competitive tubes (I needed 12), came matched and burned in for 72 hours, I figured I'd give them a try.

Swapped them out and set the bias to the Cary recommended 210-230 ma (I chose 220 ma). Noticed a few things. First, the bias with music was now rock steady at the 220 ma setting on each monoblock. And Kevin was spot on in his description of tube sound. However, each of the tubes came marked with specs including bias which were all within a tenth of 41.6 ma. That would equate to a bias setting of 246+ ma on each Six Pac. So my question is, should I stick with the Cary recommended bias of 210-230 ma or crank it to 245 ma?  

Comments appreciated,
J.Chip
128x128jchiappinelli
oldhvymec
5,101 posts
 
I own the last run of AES Six Pacs. The choke is moved from the center to the side, and a pair of small smoothing caps are added to the power supply. After that the Hexfreds, Jupiter Copper foil caps,and silver wire (take your pick). I run them at 210-220, if I'm pushing the amps. I go to 240-50 for late night listening, and low volume, kind of a winter time setting. But when I blast (hard with Six Pacs) 210-20 mA

EH valves are close to Ruby in SQ, and a LOT more dynamic, than a Golden Lyon, by far. Because I don't use valve amps for bass duty, I prefer a better Mid Bass, Dynamic (almost bloated) mids and silky smooth highs. EH GREENs are a great valve. Still not quite as freakishly GREAT as Ruby Valves and Cary products. I don't know why.. But for some reason they outperform all of the EL34 stuff.

In their, V12s V12i and V12R, ALL just sound better with, Ruby, or EH, valves. Really not the most expensive valves out there. PSVANE That's next on the list of try outs and power valves, $$$$ though. Sure make a good signal valve, 12AX7, 12AU7.

Regards
grey9hound
1,112 posts
 
These sound way better than any EL34 IMO 
Genalex Gold Lion KT77 Power Tubes
They are worth the money and are a sub for EL34
but BETTER !!
Explanation at the link below
https://www.tubesforamps.com/el34-6ca7-kt77-differences

Where to buy Quad Matched
https://www.sweetwater.com/store/detail/GENKT77QM--genalex-gold-lion-kt77-power-tubes-matched-quarte...


rodman99999
6,158 posts
 
To be clear (which I wasn't, previously), this is the query I was addressing:     "So my question is, should I stick with the Cary recommended bias of 210-230 ma or crank it to 245 ma?"    
oldhvymec
5,101 posts
 
These sound way better than any EL34 IMO
Genalex Gold Lion KT77 Power Tubes
They are worth the money and are a sub for EL34
but BETTER !!

<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>


It’s obvious you don’t own Cary/AES Six Pac, Cary V12, V12Rs, Marantz 5,7,or 9s, I DO!

The Six Pacs I own came with two brand new sets of matched GL KT-77 Sixtets. They did a super hot rodded AES 6 Pac, NO JUSTICE, they just sounded BAD. Swapped over to a set of Rubys, brighten right up.
I tried them in a V12R, for a couple of days, friggin’ valve failed. Started losing the health light on the V12R. I pulled all 6 on one side and put Rubys in, LOL THAT was an eye opener.. Night and Day difference, left and right speaker, GL vs Ruby, no contest..

That valve in ANY of the above amps won’t hold a candle to either EH or Ruby plane and simple. This is from an owner, not a guy trying to sell valves, or reading articles, someone else published. Hands on, OWNER. The only valves that are as good or maybe a tad better is old stock Mullard,Volvo, or Tellies.

American made 6CA7, sylvies, are a MUCH better valve if you can find 6 that match at a time.

KT77 GL new stock is russian made, 10% tolerance and have a high failure rate. They are dark, they do not represent what a good EL34 is all about. GL is a better bass valve but poor, at what an EL34 is.
An El34 has Poor bass, good mid bass, slightly bloated mids, and silky BUT dynamic highs.

If you want to build around a GL KT77, there is still a LOT better valve Bottom to Top than a GL, especially for the money, PSVANE is another GREAT valve, but it represents an EL34 sound, but can fetch 2-800.00 for some of their "special" valves, LOL special price. WAY to much..

BTW, 220 mA on the 6 Pac if your cranking it, Late night listening, 240-50, just don't crank it, better low volume listening.

Regards
grey9hound
1,112 posts
 
@oldhvmec1
You are correct i do not own the Cary V12, and I never said that I did. I said they were better than any EL34 that I have heard . Of course I have not heard High Dollar NOS 1950's or 1960's EL34 Who can fiknd or AFFORD those .
Your observation is with the amp that he owns , i suppose .
I am sure there is a lot better , but ,it was my observation that for the money I thought they were damn good. Of course the GEC KT-77 was probably the best ones , but finding those is like trying to use humming bird hearts for fishing bait, or pulling hen's teeth.
I tend to agree with this link.. Sorry for having an opinion !
https://www.tubesforamps.com/el34-6ca7-kt77-differences

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