Retrovalves

[Jered]

Anybody tried the retrovalves? Drop in replacement for 12ax7 and life time guarantee. But how do they sound?

http://www.jetcityamplification.com/#!retrovalves/ctjr

[xtian]

I'm curious! FETs? Hey, RG!

[roberto]

We talked about them some time ago.
LND150 like with a led instead of heaters, to glow a bit.

[Leo_Gnardo]

Before these, the FETron. Mesa used to load their amps' V1 position with these for a while in the late 70's. Didn't continue. Hmm, if it was all that and a bag of chips, why not? The new version has an LED so it "glows, like a tube."

[teemuk]

There have been plenty of these. The new ones (Retrovalves, Watt/Tonegrinders, AMT Warmstones, etc.) have advanced circuitry to specifically mimic triode like characteristics. It's not just a FET.

The aforementioned FETRON, however, was never even intented to mimic triode tubes. The pentode like characteristic curves of its FETs were found better for the application the FETRON was devised in. (Similarly as pentodes are often found better to triodes). It was also one of the key features Teledyne advertised.

I don't see why it came as such a big surprise that the FETRON wasn't providing equal performance to 12AX7's and alike. Additionally, for the same reason there's really not much sense to compare any of these new solid-state tube substitutes to FETRONs. The design goals have been entirely different.

[Mark]

The FETRONs were a hassle, I had a Mark 1 Boogie that had one and the FETRON sounded great. It was brighter with more gain than a 12AX7. If you stuck an overdrive pedal in front of the amp it might have sounded bad. When it was working correctly it sounded real good.

However the day did come when someone blew the FETRON up for me (and didn't offer financial assistance). I ordered a FETRON from Mesa Boogie and I followed the direction but I couldn't get it to work like the original one. I put a 12AX7 into the amp though it didn't sound as good as the FETRON.

http://www.philipstorr.id.au/radio/eleven/fetron.htm