Follow up review of the Gold Lion KT66's..... :}

I consider these tubes burned in now with over 100 hours on them (tubes were burned in 24 hours before I bought them according to BNB where I purchased them). The amp has pretty much been running all the time since I got the KT66's.

I did some comparisons of the KT66 tubes vs. several different branded EL34's, and a quad of 6550WD/KT88 Sovteks. In each case I much preferred the KT66 tubes over everything I have tried. I do not have any KT77's to try, nor have I heard a quad of those in a Dynaco before. If anyone has used a quad of the KT77's by Gold Lion I would certainly be interested in their opinion of that tube vs. the KT66.

I continue to be amazed at the clarity, the dynamics, and the overall depth of the sound I get from the KT66's even at volumes that I wouldn't really use. I mean loud, window rattling loud, and the KT66 tubes sound just fantastic. I cannot find any downside (except the price).

All my testing was done using Klipsch Heresey's. These old gals were made back in the late 60's I am told from the original owner who sold the speakers to me. Speakers are stock, birch plywood construction, original components as shipped from the factory. The amp uses an upgraded board I got from Kevin. The 7199's are old GE tubes that just refuse to die LOL. The rectifier is a JJ. The power trannie is an upgraded one from Heyboer, and the output trannies are original A470's. I am using a cap board in this amp from the Triode store. The original can is there but for looks alone. All my ST-70's run in Triode only.

I have listened to everything from ABBA to Zeppelin, and these tubes have performed better then any other quad I have personally ever tried. I have had no problems with the tubes, they are holding a bias of 1.26 volts on each side rock solid. I don't wash tubes, I just dust them off every once in a while so I don't know about the graphics coming off some have reported.

If any of you have a copy of the album "One Fine Morning" by Lighthouse, you won't believe the sound of the horns through these tubes. It made me laugh out loud when I heard the trumpet solo at the end of "Love Of A Woman". It was simply superb! Neil Young's 200 gram Greatest Hits was unreal. It was like Neil was in the same room. Annie Lennox on "Why" was unbelievable. When Melanie screamed out "Lay Down, Candles In The Rain", you could swear she was standing right in front of you. Freakin' Excellent!

wolverine :}

Wolverine,

I am running a new set of Genalex K-77 in my stock ST-70. I just bought them from BNB Tubes. I output to Vandersteen 2s. Other amp tubes are a NOS Mullard GZ34/5AR4 and NOS RCA 7199s.

While the tubes are still in the burn-in stage, they sound fantastic; warm, full and with great sound stage qualities.

My only complaint is the KTs caused my amp to run HOT, HOT, HOT. I was fearful of burning up the transformer, or who knows what else. Previously I was running Ruby EL34s and the output transformer ran cool to the touch.

I originally biased the KTs @ 1.25 VDC. On Bob's advise, I have lowered the bias to 1.15VDC and the transformer is now running cooler, but still warm to the touch, but not nearly as hot as before.

I hope I have not harmed the unit (I've had this unit since I built it in the mid 60s) and/or tubes and that I don't miss out on the sound quality with the lower biasing.

I'd love to hear from anyone else who might have had the same issue and how or if they solved it.

Bruce

Thanks for the follow up. I noted that you are running a stock setup, does this mean you have the original PA-060 installed? Also, did you expand the bias at all?

I have read excellent reviews on the KT77 tube and I am considering buying a quad. My research led me to get the KT66's instead mostly because of what Bob and others here had reported on their experience with that tube. I consider Bob to be as close to an expert on these units as I have ran into and his opinion was the KT66 is the finest sounding tube he has used to date.

On a side note, the VTA board that Roy sells is also highly prized by Bob. I bought one assembled and after three attempts I finally got the board to function and bias correctly, however after a few months the power supply (a new upgraded one) burned out so I have it sitting on the shelf at the moment.

I had a devil of a time getting the board to function in the first place. A few emails to Roy and Bob, changing the NFB over to the 8ohm load, and I had the amp operating but it always had this weird background noise. When hooked up to the 16ohm load the amp made a whispy whirring sound that was very loud, the 8ohm tap took that away, however I believe it was still not set up right as that power supply ran very hot all the time and finally did burn out. I had purchased the upgraded PA-060 from Kevin over at Dynakit and bless his heart he was very good about offering me free shipping on my purchase of a couple Mark III's that I asked him about. That's my next project when I finally get the money to go. Kevin's a good man, I've bought a lot of stuff from him through the last few years including power supplies, output transformers, misc. odds and ends.

I took the amp to a local TUBE HEAD GURU at a repair shop and he could find nothing wrong with the amp and suggested I didn't use the VTA board until I could get the board right. It still sits on the shelf LOL.

Thanks for the feedback on the KT77! I appreciate your time... :}

wolverine