Hello RATs

I have 2 pairs of KT88. A pair of Hammond 1650N OT and 2 pcs 400 volts power
traffies.
Is a Dynaco Dynakit Mark III or KAT88 from WAD the best sounded amplifier or
is it another amplifier. Pleass help with input

Regards Benny

Hi RATs!

Nobody knows

Build an amp and listen. Then, after a while, change something in the circuit
and listen some more. If you like it better, keep it that way, if not, put it
back.

It would be great if the perfect amp already existed, but, perhaps, less fun

Happy Ears!
Al


Alan J. Marcy
Phoenix, AZ

PWC/mystic/Earhead

"Benny Højvælde" wrote:

Hello RATs

I have 2 pairs of KT88. A pair of Hammond 1650N OT and 2 pcs 400 volts power
traffies.
Is a Dynaco Dynakit Mark III or KAT88 from WAD the best sounded amplifier or
is it another amplifier. Pleass help with input

Regards Benny

You can try the circuit at

http://www.turneraudio.com.au/htmlwe...0ulabinteg.htm

6SN7 or the 6H30 can be used instead of 6CG7, and B+ can be
lower than 500v as shown since your 1650N Hammond OPTs
are for 4.3 k load, and this load is best suited to KT88/6550 working
to make mainly class A when Ea = 400v is used with the UL connections.
The 1650N is also well suited to 4 x 6CA7, which would be better than a pair of
KT88 imho,
and a lot cheaper to buy, and the tubes don't have to be set up with high idle
currents
to still get a decent glorious amount of class A.

KT88 or 6550 have a Pd max rating of 42 watts, but I only ever run them
at about 27 watts Pd at idle.

With 6CA7, the Pd max rating is 28 watts, and 20 watts is a sensible idle Pd.
But with 4 tubes instead of a pair, you have 40 watts each side of the PP
circuit,
and the higher total idle dissipation allows more class A.

The load for a pair of tubes for a lot of class A is about 8k.
So if the load from the OPT is about 4k, ( like you will have ),
then if you have 4 output tubes, ie, two pairs, then each pair "sees" 8k,
and it is a very good load match.

One pair of 6CA7 will make about 32 watts in UL class AB1 with Ea = +400v, Ia =
50 mA,
and load = 8k a-a, with the first 10 watts in class A.
With 4 tubes, you can get 64 watts, with the first 20 watts in class A.
Using one pair of KT88 you will only get 50 watts with a 4k load.

But if all you use is 2 watts average power like most ppl, then
the KT88/6550 option is quite OK.

Patrick Turner.