One of the oldest DHT tubes is the 10 , with near identical substitutes the 10Y and 801A.
Although not rare, it is sometimes difficult to get good NOS matched pairs.
It's perhaps one of the finest DHT tubes to use in a preamp, it has a lovely tone and very balanced sound.
I've built a few 10 preamps for myself over the years, but never sold one as I was worried about tube replacement.
I've just finished building this "copper finish" preamp (all the Supratek preamps have copper chassis which is usually chrome-plated or powder-coated).
It was built to be used at an upcoming hi-fi show, but I've decided to use a production preamp with more available tube (4P1L or 300B) instead.
The 801A is conservatively run and they last 10's of thousands of hours, I'm still using the same tubes in the first 801A preamp I built around 10 years ago.
This is a DUAL CABERNET preamp with two line stages. The 6SN7/801A is the DHT output and it also has a 6SN7/6H30 line stage with volume control to be used in active systems, for example driving the bass amplifier , while the DHT section drives the mid/treble amplifier.
Or either stage can be used on their own. The 6SN7 driver stage can also be switched out when a low gain preamp is required.
The 6SN7/6H30 stage is a wide bandwidth , state of the art
design with outstanding technical specifications, which also sounds excellent.
The 6SN7/801A linestage has all of the Supratek DHT qualities , reinforced by the use of perhaps the best DHT preamp tube ever made.
The finest components have been used- Mundorf capacitors, Magnequest output transformer etc.
