3B7 Loctal DHT

[Klimon]

Looking for curves / operation points / testimonies about this tube.

Thanks!

Simon

 

[revintage]

http://frank.pocnet.net/sheets/127/3/3B7.pdf

Curves look nice from 2-3mA and up. Ra should be in the ballpark of 10kohm.

Why not parallell the halves for a transformer coupled (4:1) SE pre?

 

[andyjevans]

I tried using the 3B7 but found it harsh. I didn't scope it, so there's a real possibility that it was oscillating and needed a bigger grid stopper. So if you have a go at listening to one, put a decent size grid stopper on it.

andy

 

[revintage]

Thanks Andy,

Is there a DHT you haven´t tried ?

By the way, are they easy to find?

 

[andyjevans]

Is there a DHT I haven't tried?

Yes - megabuck ones like the 50, and esoteric new production.

Also I haven't yet tried out the European ones I've been buying - RE034, 074, 084, 134

But seriously, there were loads of different DHTs made. I've probably tried most of the popular ones which were about in large quantities.

I think the 3B7 is quite easy to get - dealers should have them.

andy

 

[Klimon]

Interesting, thanks!

Simon

 

[nafunga]

DHT

Regarding DHT small signal types available in the UK, the LP2, PM2A etc, range of 2v filament valves are readily available from the usual sources i.e, Colomor and Langrex. The types mentioned were originally designed for audio output stages (approx. 0.1W) but make very good drivers for larger rated types. I use them to drive VT-25's etc. They work well.

Regards,

David.