You ALL Need To Try KT77's - (NO---I Am NOT a Salesman)
Posted: Mon Mar 20, 2006 1:59 pm
OK---to let you all know, I am fairly new to Shannon's diytube site.
This is great! I am already hooked on the brand new Poseidon driver board for the Dynaco MK4. I have been wanting to build up an old amp for a long time as a hobby, both for the experience and the fun.
I will post pictures and details as the project progresses. At this point I have gutted the amps COMPLETELY, and have sent the chassis out to be re-chromed along with the bell covers off the transformers. OK, OK---I want them to be pretty too.
What I really wanted to talk about were some tubes. The KT77 tubes being re-introduced by JJ Electronics:
http://www.jj-electronic.sk/pdf/KT77.pdf
In a word-------INCREDIBLE!!
Now for you younger generation, the KT77 was a little know tube mad for the military as a VERY RELIABLE and INDESTRUCTIBLE replacement for the EL34. Here are a few details: http://www.mclink.it/com/audiomatica/tubes/kt77.htm.
The other good news is it will withstand much higher plate voltages, is DEAD QUIET, and any "microphonics" problems are eliminated.
The great thing is this tube sounds FABULOUS, and better than any NOS Mullard! Go out and try to price some NOS KT77 tubes and it's enough to give you a heart attack.
The KT77 is designed primarily for use under ultra-linear conditions (43% taps, Class AB1 push-pull) and this connection is recommended. Similiar performance can be obtained in the tetrode connected mode, but the output impednace (zout) will be higher. Life expectancy=5000 hours when operated at maximum ratings of 32W, or 10,000 hours when operated at the 25W ratings of most Dynaco amps (MK2, MK4, or ST-70).
The original KT77 tubes are very rare, and are a direct replacement for the EL34 or 6CA7.
This tube was only produced Marconi-Osram Valve Co. (later Genalex). The early Genalex KT77 had a skinny bottle with a flat top similar to the Mullards and had a red Genalex decal on it with two halo getters on top in a "stacked" configuration. Later versions went to a black octal base similar to the XF4 Mullards---but NOT Mullards!! These are probably the rarest, and most expensive, of all EL34 types today. Usually, the early thin brownbase versions will cost the most due to their rarity, and the blackbase types will be a little less, but you will easily pay $180 or more PER TUBE!
These are all EXCELLANT tubes, and out perform the best Mullard XF1 tubes, but are so rare worldwide they are not often found.
Enter JJ Electronics!! Heros!!!
(OK- not really heros, but great guys.)
They bought the original Marconi Osram Valve equipment and have re-introduced this incredible tube by building it to the exact specs using the original manufacturing equipment.
I (being the ultimate sceptic because I remember the original KT77 tubes) recently bought 2 matched quads of thes new KT77's and popped them in my Conrad Johnson Premier 4 tube amp (100 WPC all tube using one quad per side). I COULDN'T BELIEVE THE DIFFERENCE!
These tubes were amazing right out of the box! I cannot wait until some "break-in" time goes by.
I had a set of 2 matched quads of Svetlana EL34 tubes and a set of 2 matched quads of the overpriced Valve Art "Cryo Stabilized" EL34 tubes to compare the new KT77's against. THERE IS NO COMPARISON!
I now have a lot of matched Svetlana and Valve Art EL34 tubes for sale if anyone is interested.
YES!-----They are that good.
At the current price of about $17 each (matched), you can't affort NOT to try them!!
I highly recommend that you try these tubes in place of your existing EL34 tubes. You will NOT be disappointed!
Sincerely,
-Pat
This is great! I am already hooked on the brand new Poseidon driver board for the Dynaco MK4. I have been wanting to build up an old amp for a long time as a hobby, both for the experience and the fun.
I will post pictures and details as the project progresses. At this point I have gutted the amps COMPLETELY, and have sent the chassis out to be re-chromed along with the bell covers off the transformers. OK, OK---I want them to be pretty too.
What I really wanted to talk about were some tubes. The KT77 tubes being re-introduced by JJ Electronics:
http://www.jj-electronic.sk/pdf/KT77.pdf
In a word-------INCREDIBLE!!
Now for you younger generation, the KT77 was a little know tube mad for the military as a VERY RELIABLE and INDESTRUCTIBLE replacement for the EL34. Here are a few details: http://www.mclink.it/com/audiomatica/tubes/kt77.htm.
The other good news is it will withstand much higher plate voltages, is DEAD QUIET, and any "microphonics" problems are eliminated.
The great thing is this tube sounds FABULOUS, and better than any NOS Mullard! Go out and try to price some NOS KT77 tubes and it's enough to give you a heart attack.
The KT77 is designed primarily for use under ultra-linear conditions (43% taps, Class AB1 push-pull) and this connection is recommended. Similiar performance can be obtained in the tetrode connected mode, but the output impednace (zout) will be higher. Life expectancy=5000 hours when operated at maximum ratings of 32W, or 10,000 hours when operated at the 25W ratings of most Dynaco amps (MK2, MK4, or ST-70).
The original KT77 tubes are very rare, and are a direct replacement for the EL34 or 6CA7.
This tube was only produced Marconi-Osram Valve Co. (later Genalex). The early Genalex KT77 had a skinny bottle with a flat top similar to the Mullards and had a red Genalex decal on it with two halo getters on top in a "stacked" configuration. Later versions went to a black octal base similar to the XF4 Mullards---but NOT Mullards!! These are probably the rarest, and most expensive, of all EL34 types today. Usually, the early thin brownbase versions will cost the most due to their rarity, and the blackbase types will be a little less, but you will easily pay $180 or more PER TUBE!
These are all EXCELLANT tubes, and out perform the best Mullard XF1 tubes, but are so rare worldwide they are not often found.
Enter JJ Electronics!! Heros!!!
(OK- not really heros, but great guys.)
They bought the original Marconi Osram Valve equipment and have re-introduced this incredible tube by building it to the exact specs using the original manufacturing equipment.
I (being the ultimate sceptic because I remember the original KT77 tubes) recently bought 2 matched quads of thes new KT77's and popped them in my Conrad Johnson Premier 4 tube amp (100 WPC all tube using one quad per side). I COULDN'T BELIEVE THE DIFFERENCE!
These tubes were amazing right out of the box! I cannot wait until some "break-in" time goes by.
I had a set of 2 matched quads of Svetlana EL34 tubes and a set of 2 matched quads of the overpriced Valve Art "Cryo Stabilized" EL34 tubes to compare the new KT77's against. THERE IS NO COMPARISON!
I now have a lot of matched Svetlana and Valve Art EL34 tubes for sale if anyone is interested.
YES!-----They are that good.
At the current price of about $17 each (matched), you can't affort NOT to try them!!
I highly recommend that you try these tubes in place of your existing EL34 tubes. You will NOT be disappointed!
Sincerely,
-Pat