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Thanks for the shoutout guys haha! Yes I was looking for a 5687 that I could use as a replacement for the 6N6P in the driver stage for my Schiit Valhalla (with an adapter of course) and the 5687 came up as a similar replacement but with a different pinout so I needed to get an adapter along with the 5687. So far I only managed to get a Sylvania 5687WA but I'm hoping to pick up both the Raytheon and Tung Sol from you guys in my next order.
I'm fairly surprised you guys just recently found out about the 5687. It's a long-time favorite among tube hi-fi amplifier designers. One of the very best SET amplifier driver tubes available.
Years ago I discovered the 6N6P, which is a very similar tube, but superior in every way IMO to the 5687 - standard pinout, larger bottle for better heat dissipation, and almost certainly a longer lived tube (in bench experiments we've never damaged one) and most importantly it sounds amazing. One thing I do as a designer is to never follow what everyone else is doing, that has allowed me the freedom to choose superior tubes and circuits for each Kit Amp Design. I think it's great that a lot of SET designs utilize a relatively unknown tube, as time goes on we'll need those lesser known vintage tubes to replace the more common types as they go extinct.
I have Raytheon 5687WA bronze plates (gain side) paired with Telefunken ECC 801s on a cap modded Schiit Freya+. The 900ma(5687) 300ma(12AT7) splits the available heater current correctly and IMO the high current 5687 sounds better than any 6SN7 i tried in Freya.
150V plate-to-cathode and 20ma is a good operating point. Unfortunately, you can only use one triode half of the 5687 when used at this high-current operating point due to maximum combined plate dissipating ratings for the 5687. One-half of a 5687 is an excellent driver for the 300B triode --MUCH superior to the 6SN7 in this application. If you want to use both triode halves, then you must adjust the operating points to a more modest plate-dissipation in order to avoid exceeding the combined/total maximum plate dissipation rating for the tube.
Hi Ronfree, It looks like it can be used with correct adapters (This is very important!). But you need to be very careful about heater current. The Freya + and Freya Noval have a maximum of 2.4A of heater current available. The 5687 running at 6.3v heater draws 900mA. So two of them draw 1.8A, leaving 600mA to work with for two tubes. So if you run a pair of tubes that draw 300mA each or less then you should be safe. Of course, this amp wasn't designed for this tube so your mileage may vary. Always research and double check what you intend to do ahead of time to ensure that it's safe for both you and your amp. Edit: Forgot to talk about how it sounds. In my opinion it's very similar to a 6N6P, and I think it has a lot to do with the high current nature of both tubes. In our prototype testing preamp, prototype headphone amp, and universal 6or12SN7 kit preamp, they all present with a deep extended base and excellent mids. Personally I think I prefer the 6N6P over the 5687, but I might be a little biased.
Hi MasterofPlay7, there are a few reasons. We don't have a lot of variety of them in stock. We do have some lovely examples of the 6N3P made in Oktyabr plant in Ukraine. But unfortunately we don't have any amps we can play them in (at the moment), so we can't exactly talk about the sound. But considering how easy it was to modify a 9 pin socket saver to work with the 5687, I might rig one up to adapt a 6N3P to a 6DJ8 style pinout and see how they sound in our prototype testing preamp. We also haven't had much demand for them, I think we've only had two requests for the tubes in the last year. So it's not something we think about very much. But maybe we'll talk about it more in the future and try to find some other options to show. Cheers!
