Test with 5755 tubes with adapter in Peavey Classic 30

[tonepoet]

With the cost of NOS 5751 tubes gone insane, ($30 to $69 per tube!!!) there is an alternative tube I've read about using as a substitution and that is the 5755 tube, which requires an adapter base to change the tubes pin out.

I purchased two Raytheon JAN 5755 tubes on eBay (Which were about $6 each) and also two of the adapter bases from another seller (About $13).

The adapter bases I got do work and the tubes did test like new on my tube tester.

I'm not sure what the original application for this tube was, but since I've never seen the tube on an amp schematic, I'd guess audio was not an application.

I put one in the V1 position of a Peavey Classic 30 and they do work. However, I'd say they aren't very musical. There was nothing chimey or shimmering about the high end and overall, the sound was rather dull compared to the new JJ 5751 that is available.

I may try brands of 5755 tubes other than Raytheon to see if I can find one that sounds like a 5751 tube, but didn't think the Raytheon was the one.

[kleuck]

I'm not sure what the original application for this tube was, but since I've never seen the tube on an amp schematic, I'd guess audio was not an application.

They were intended for a bunch of usages, but have according to the Raytheon datasheet protected against microphony, so they should be usable in amps, some other tubes sometimes used in audio circuits like
12AV7 are VERY microphonic, or even the 12BZ7.

[tonepoet]

Thanks kleuck, I'll try some other brands before I abandon the idea.

[kleuck]

They were meant for instrumentation and the like, so very linear and symmetrical i suppose, not the best for guitar.I have a Mazda S like that : awesome tube for a mic preamp (no microphony, no noise, linear etc) but not very juicy in guitar amps.