Anyone Seen This Design

[Studerfreak]

Looking at the inside and noticing quite recent IC's and voltage regulator, I suppose that these things are more recent than the front panels suggest.
The BNC's may be connectors used for linking the things together for stereo operation.
The function of the 9-pin connectors is a complete mystery for me.
The art of soldering suggests it to be a home made project.

[Richard Crowley]

There is nothing visible in the interior photo that would suggest that there is anything remotely resembling a computer interface (serial or otherwise) in there. DB9 does NOT imply an RS-232 serial port.

It looks semi-home-made. The completely uninsulated and exposed anode caps on the back panel are an outrageous safety hazard and would have NEVER passed any sort of official approval.

[Studerfreak]

Looking carefully at the photograph of the back panel you will notice that where the 9-pin connector is mounted there first was a circular hole drilled.
This makes this set a DIY project to me.
Indeed the wiring of the tubes at the back can be quite lethal.
Again: DIY without sufficient technical background ?

[brianroth]

Some octal tubes had GRID caps, and the magic marker designation I can barely see is a 6L7 (a heptode/pentagrid converter). The control grid appears on the top cap.

Bri

[Studerfreak]

I also think it is a 6L7 in which case the top connection indeed is the grid.

[Matt Syson]

Hi
The red 'lacquer' on some of the screws suggests it was wired by a 'professional' as this used to be a way of indicating that it had been checked over by a 'QC' person rather than as a 'screw locking' method.
Possibly had a circular connector for 'linking' or other function which has subsequently been replaced by the usually much cheaper Sub D 9 pin once the old circular connectors on the cable had been lost.
Control grid on the top cap is relatively safe electrically, but a physical guard of some sort to stop the valves being broken would have been good.
With that 'era' of valves it is possibly something on the lines of the old RCA comp / lim designs but with solid state 'sidechain'. However simply using the same valves will not make it 'sound' like the 'classic' units (however bad they are).
Matt S

[facloud]

thanks for checking it out peeps, apparently it was built by Eric P. Dollard... or at least that's what the seller is claiming which gives me some hope that they were put together decently. i can't find any literature on the design or the unorthodox connectors on the rear. I'll be happy if they work well!