Nic Rhodes
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There is a very good article on these dissimilar triodes in Vacuum Tube Valley. A gold mine of potential that few have exploited so far.
There is a very good article on these dissimilar triodes in Vacuum Tube Valley. A gold mine of potential that few have exploited so far.
If you can find them, if you know of a source i would be interested and the last time i saw some they where at least$20.00 each and that was about a month ago .they are hard to find unfortunately
The 300b tube is never easy to drive which is why many people use 5687 / C3gs / smaller power triodes etc to do it properly. The 6DN7 and other dissimilar tubes have many other uses and have a firm following in small amps / headphone amps though their use originally was driven by tvs. Heathkit I think uses them in the 60s in ham radio transmitters and more recently Bottlehead S.E.X. kits. I have used them to drive transformers in a RF driven 300B but this is not what I would consider first for driving a 300b, personally I like 3A/167Ms. Interstingly this is a US only style of valve, the UK and European did virtually non of these prefering ECL type valves (ala ECL83 used in headphone amps here in the UK). The dissimilar triodes I think work really well in the Woo 6 series. The 6SN7GT is a lovely valve, just not one I would use for a 300b amp driving it directly a la Woo.
By any chance does anyone have any 7N7 to 6SN7 adapters they aren't using? I'm looking for 1 or a pair.
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I am sorry to just jump in the discussion and change a subject. But there is this burning question that I need help.
I have Little Dot MK VI+ and it can use 6sn7 and 6sl7 as driver. I really want to use C3G as driver. Is there an adapter or some way to accomplish this? Is this even possible?
Any help would be appreciated.
Yes, it is possible. But to do so requires a custom adapter to connect two C3gs into one 6SL7 socket. This adapter must accomplish two functions. First, since the C3g is a pentode, it will have to convert the C3Gs into triodes. And second, the adapter will have to reroute the cathode, grid and plate of each CG3 to the appropriate pins in the 6SL7 socket as well as the heaters.
As an example, it might look similar to this 6J5 to 6SN7 adapter, but with loctal sockets on top, instead of octal.
http://www.ebay.com/itm/1x-6J5-6J5-to-6SN7-Vacuum-tube-adapter-socket-converter-02-/301539001598?
If you are not up to building one of these yourself, you might want to contact one of the eBay vendors who build various adapters and ask if they would be willing to build one for you. In response to just such a request, at least two different vendors have built C3g to 6AK5 adapters for the Little Dot 1+. II, III and IV.
Cheers!
Edit: I have no idea how a C3G will sound in a circuit designed around the 6SL7. So if you decide to give this a try, please let us know how it turned out.
In a circuit that wasn't designed for the C3g it's anybody's guess what kind of results you are going to get. The tube might end up with less than ideal biasing. Properly driven the C3g is as close to "soundless" as a driver as I have heard in terms of coloration or deviation from neutral. It has little in the way of a signature you could describe with words like "warm" or such. What it will do is make more obvious the coloration of any tubes downstream from it, for better or worse.
Thank you so much for clearing this up about the C3g's characteristic. So hypothetically if you had a hybrid tube amp (tube preamp and solid state power output) with C3g properly driven...it would just sound like a SS amp with good preamp, right? Basically it will be "soundless" or add any tube color so you will be listening to the sound that is closest to how it was originally recorded, right?