Gold Lion KT77 vs KT66

[mopardave]

Anyone here ever AB these two tubes.   Thinking about ordering a new quad and not sure the differences in the two.   Will be used with my CW's and Super Heresy's.   Thanks

[robert_kc]

What amp?  Am I correct in assuming your amp supports both KT66 and KT77?

 

I own an Inspire “Fire Bottle” SE Stereo Tube Amplifier HO single-ended-pentode amp (originally equipped with KT88, 6CG7, 5U4).   I’ve not tried KT77.    (As you’ll see below, KT77 are one of the few supported output tubes I haven’t tried … tube rolling is a sickness …)  However, I have tried EL34, in addition to Gold Lion KT66.

 

The speakers in the system with my Fire Bottle SEP amp are RF-7II.

 

My favorite tube combination, based on my preference for warm, rich sound listening to hi-res classical and opera recordings:  6L6GC / 5V4G / 6DJ8.  

 

Specific favorites:

 

Output:   

• Best overall sound:  Groove Tube Gold Series GT6L6GE Performance Rating 5 (#2: Russian military 6P3S-E, Honorable mention: Tung-Sol 6L6G (coke bottle 6L6GC), Tung-Sol KT150, Gold Lion KT66, vintage Sylvania 5881)
• Best Value:  6P3S-E
• Best combination of sound and aesthetics:  Tung-Sol 6L6G, Gold Lion KT66

Rectifier:  Sylvania JAN 5V4G  (#2 : various 5V4G & 5V4GA, #3 Mullard 5AR4)
 

Input:  Amperex 6DJ8 (Holland)

 

 

Here’s the output tubes that I’ve tried in the Fire Bottle SEP amp: 

• Zenith 6V6G (vintage)
• Sylvania 6L6GA (vintage)
• Sylvania 7408 (vintage, 6V6 variant)
• Mullard EL34
• Bugle Boy EL34 (vintage)
• Russian 6P3S-E (Russian military surplus 1980s 6L6GC equivalent)
• Groove Tube Gold Series GT6L6GE (6L6GC)
• McIntosh branded GE 6L6GC (vintage)
• GE 6L6GC (vintage)
• Tung-Sol 7581A (6L6GC variant)
• Tung-Sol 6L6G (6L6GC in a big bottle)
• Gold Lion KT88
• Tung-Sol KT150
• Gold Lion KT66
• Sylvania 5881

 

IME, 6CA7/EL34 can deliver excellent overall sound.  (I run 6CA7/EL34 in Scott 272, Pilot SA-260, Fisher X-1000, and until recently I had a Scott 210F.)   I prefer the “warm” sound of the 6L6 family.  (I run GL6GC/KT66 in the Fire Bottle SEP, Scott 296 x2, McIntosh MC240, MC30 x2, Pilot HF-56 x2. Altec 353A, and Fisher TA500.)   Of course, this is based on my speakers (RF-7II, Snell Type CV, Klipsch Palladium P-37F, JBL L880), in my rooms, my music, and my preferences.

 

I’ve been happy with the new production Russian Gold Lion output tubes.  If your amp will accommodate both EL34 and 6L6GC type tubes, you might try the Gold Lion KT77, and – for a warmer sound - the Russian 6P3S-E 6L6GC (which are very reasonably priced).

 

That’s my 2.5 cents.  

[mopardave]

Thanks for your response and experience in tube rolling.  Just the person i need info from.    I'm not sure the amp will support the kt66's.  Way back some 15yrs ago, I had Craig@nosvalves mod this Audcom amp(HK citation 2 replica) and he gave me a quad of valve art kt66 to try.  The bias would run away to a point i could not turn it down.   Thought i might try again with a new set of cold KT66 GL and see if it will bias.  Where should these KT66GL be biased at?     I want to try a set of the KT77GL as well.     I used to think the Electro Harmonix fat bottles were the cats *** in this EL34 amp til i tried the JJ KT77.   Simply one bad *** tube with Cornwalls.  They go low with strong punchy accurate mids and cristal clear highs.    So, thought i would try the KT77GL to compare to the JJ's and the KT66's if i can get then to bias.    Thanks again

[robert_kc]

I’m not a technician.  I’m afraid I can’t answer your question about setting bias. 

 

Craig / NOS Valves has rebuilt several amps for me.   (My other amps were rebuilt by other techs before I bought them.)

 

My amps fall into 3 categories: 

1. Auto-bias (e.g., McIntosh)
2. Adjustable bias, with test points on top of chassis  (I’m able to adjust these)
3. Adjustable bias, without test points on top of chassis (I don’t know how to adjust these … I need to learn … someday …)

 

AFAIK, my only amp that accepts more than one type of output tube is my Fire Bottle SEP (designed and built by Dennis Had).   With all of my other amps, I stick with the specified output tubes (other than minor variants within a family).  (BTW, Craig makes an amp that accommodates different output tubes called VRD – Valve Roller’s Dream – but I don’t own one … I’d have to sell something to make room …)

 

Bottom line:  I don’t know if a KT66 would work in your Audcom amp, or how to adjust bias.   What about a 5881?  7581A?  KT150?  These all sounded good in my Inspire SEP amp, driving RF-7II.  

 

IMO, KT88 are too “bright” sounding.  My MC275 and Scott LK150 use KT88 – and they potentially can sound good – iff I use a pre-amp and attenuate the treble.  (I can run all of my other power amps directly connected to an Oppo universal player – i.e., no pre-amp.)

 

Regarding EL34, my Pilot SA-260 is equipped with JJs, and it sounds good.  My Fisher X-1000 has RCA 6CA7 fat bottle, and it sounds good (different system).   My Scott 272 has Groove Tube – I don’t think I’ve tried different output tubes in this amp.   I regret selling my mint Scott 210F mono integrated amp that had Amperex Bugle Boy, Made in Holland.

 

Maybe Craig will post a response about your Audcom amp.

 

Good luck, and keep us posted.  

[mopardave]

I searched a little more on this topic and found some old klipsch forum threads and craig said back then(2003) to try it, but i might hate or like it.    Think i'll just order up some new gold lion KT77's and be happy.   Wounldn't want to hurt my amp.    Cant do any hard listening as all my gear is crammed into my computor room at the moment.   Looks like you have alot of nice gear. I have never researched those KT150 tubes or the others.    Thanks