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Vintage threads from the first ten years

KT66's . How do they sound ?

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5/15/1998 3:17 AM
Nick	KT66's . How do they sound ? Does anybody know how they sound ? A couple of years ago I heard that they were fantastic . Early Marshalls have them.

5/15/1998 12:21 PM

Real KT66 valves (MO valve company, GEC/Marconi/Genalex) tubes are probably the best sounding high output tube in my opinion. Very big broad amplification right through from deep base to crystal treble. Highly prized by hifi people but they distort in a wonderful manner in guitar amps. They are the the sound of the early Marshall JTM45/Bluesbreaker - listen to 'Stepping out' by Eric Clapton. Only trouble is that they cost a fortune and I forever think of the damage and shortening of their life when I run mine heavily distorted. Cost wise here in the UK, if you hunt around, genuine 'new old stock' KT66's go for Ł120-150 per pair and tested second hand ones are typically Ł30 each.

Peter

5/15/1998 3:09 PM
Derrick	Peter, I just bought a '66 Marshal JTM-45 and I need a pair of MO Valve KT-66's to compleat it! I am not interested in too many of the valves made today. They don't seem to handle the current,voltages, etc. that old stock valves will. Plus the tone! What would you recomend I do to find a pair of them from UK at those prices? Thanks, -Derrick

5/16/1998 9:47 AM

I was doing some tube comparisions recently with a '64 JTM45, a '65 JTM45, and a '66 JTM100. All are equipped with GEC KT66s. I also threw another '66 JTM100 in the mix with Mullard EL34s. I threw a set of GE 6L6GC in one of the JTK45s for comparison sake. What you will notice about KT66s, is that when puched, they are a loose, crunchy sounding tube. Surprisingly, the GE 6L6 actually sounded better to my ears in the JTM45 where full-clown distortion is concerned, but that's just my opinion. The KT66 has a looser feel, and seems to lose just a little definition when cranked. For the bluesy overdrive sound however, it is very nice. If you want to achieve the searing sound of the Clapton/Bluesbreakers (since it was mentioned), you'll need two other items: (1) Alnico speakers, (2) a repro of the early Dallas Rangemaster booster. The alnicos will more accurately reproduce the searing tonal character of these recordings, and I strongly believe is what Clapton's amp was equipped with. Not many people know about the 'ol germanium Rangemaster being used in Clapton's rig, but it is the key to the sound, take my word for it! I have a friend who reverse engineered one and builds them from scratch. Amazing difference!

As for the 100W amps, I found that the EL34s made the amps sound a just like the early Hendrix stuff, very characteristic. The KT66s sound a little creamier, but get a little 'fuzzy' around the edges when pushed.

If you wwant a pair of KT66s, the new Tesla KT66 is the most accurate tube reproduction made, in my opinion. I was informed of this in advance by a well respected JTM45 owner who had an opportunity to pit them squarely against his GEC tubes. He was very impressed. I just recently had an opportunity to try a pair, and was likewise so impressed, that my days of buying high $$$ GECs are over!

Ted B.

5/16/1998 10:35 AM
Peter	I have also heard that there are some new KT 66's on the market - I think Groove Tubes supply some but I don't know the price. As regards UK suppliers you might try Watford Valves (tel 01923 893270) or Wilson Valves (tel 01484 655699) or Colomor Electronics in Goldhawk road, London.

5/16/1998 12:31 PM
Ted Breaux	Yes, the new KT66s are distributed by Groove Tubes, and are made by Tesla, of which Groove Tubes owns a percentage. I suspect that anyone who distributes Tesla products will soon be able to get them if they can't already.

5/16/1998 3:22 PM
Peter	This Dallas Rangemaster sounds interesting and I didn't know it was used by Eric Clapton on the Bluesbreaker album. Is there any schematic of this around on the web to your knowledge? Thanks Peter

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