In my audio system I use amplifiers with GM-70 and GU-48 tubes at output stages. Since the GU-48 solution showed certain advantages with big PMC EB1i speakers, I decided to offer for sale the accumulated GM-70 tubes of four different modifications:
1) ordinary ones with graphite anode 25usd e.a. (6 pcs)
2) tubes with graphite anode but produced in 1960s by Photon factory 50usd e.a. (8 pcs)
3) tubes with a copper plate 75usd e.a. (4 pcs)
4) rariests tubes with an "iron" anode and brass tube base 175usd e.a. (2 pcs)
All tubes have been checked and some have been tested by installing them into GM-70 amplifier and by listening. Except for the rare ones with "iron" anode, all tubes are NOS with a duration of operation for the period of measurements and tests. Iron anode tubes were in use, but measured by the former owner at anode voltages of 500V and 400V (results are indicated by a marker on the glass). By sound (I have tested), they also show normal operation. Photos of all offered tubes are attached. GU-48 tubes with metal plate are offered in other thread 125usd e.a.
1) ordinary ones with graphite anode 25usd e.a. (6 pcs)
2) tubes with graphite anode but produced in 1960s by Photon factory 50usd e.a. (8 pcs)
3) tubes with a copper plate 75usd e.a. (4 pcs)
4) rariests tubes with an "iron" anode and brass tube base 175usd e.a. (2 pcs)
All tubes have been checked and some have been tested by installing them into GM-70 amplifier and by listening. Except for the rare ones with "iron" anode, all tubes are NOS with a duration of operation for the period of measurements and tests. Iron anode tubes were in use, but measured by the former owner at anode voltages of 500V and 400V (results are indicated by a marker on the glass). By sound (I have tested), they also show normal operation. Photos of all offered tubes are attached. GU-48 tubes with metal plate are offered in other thread 125usd e.a.
Attachments
Parcel for Jim has been prepared. Each tube is wrapped by soft materal 4 layers, then all 4 tubes are wrapped 6 layers, then empty space in the box is filled by soft particles.
Some tubes (8pcs) have been sold, remaining tubes are:
1) ordinary ones with graphite anode 25usd e.a. (2 pcs)
2) tubes with graphite anode but produced in 1960s by Photon factory 50usd e.a. (8 pcs)
4) rariests tubes with an "iron" anode and brass tube base 175usd e.a. (2 pcs)
1) ordinary ones with graphite anode 25usd e.a. (2 pcs)
2) tubes with graphite anode but produced in 1960s by Photon factory 50usd e.a. (8 pcs)
4) rariests tubes with an "iron" anode and brass tube base 175usd e.a. (2 pcs)
Some tubes (4pcs) have been sold, remaining tubes are:
1) ordinary ones with graphite anode 25usd e.a. (2 pcs)
2) tubes with graphite anode but produced in 1960s by Photon factory 50usd e.a. (4 pcs)
4) rariests tubes with an "iron" anode and brass tube base 175usd e.a. (2 pcs)
1) ordinary ones with graphite anode 25usd e.a. (2 pcs)
2) tubes with graphite anode but produced in 1960s by Photon factory 50usd e.a. (4 pcs)
4) rariests tubes with an "iron" anode and brass tube base 175usd e.a. (2 pcs)