Description
The 6CG7 / 6FQ7 are 9 pin direct equivalents to the 6SN7GTB.
The 6GU7 is a 9 pin medium Mu (gain) twin triode, that has similar (not identical) electrical specifications to the 6SN7GTB and is a close cousin to the 6CG7.
With a 9 pin to 8 pin octal adapter you can use the 6GU7 / 6CG7 / 6FQ7 in most 6SN7 circuits.
Stanton Bailey (verified owner) –
I actually bought two of each 6GU7 available to see how they compared to the 6SN7’s that I’ve been using in my preamps. I used the recommended 9 pin to Octal adapter sold here. The Schiit Frey+ and the MTK Universal Preamp were used for my testing into the GU50 monoblocs. I compared these 6GU7’s mainly to the JAN military 5692 RCA red base NOS, Sylvania 6SN7GTA (NOS) and Tung-sol 6SN7GTB (NOS).
The 6GU7’s had a very airy high end with amazing clarity and very nice resolution. Good but a tad less musical charm than the others. The midrange was upfront, organic and present with a very full body and reality that was as good as the other tubes. The bass was good but not as bold and coherent as the other tubes.
The 6GU7s held up vey well in almost every category compared to the much more expensive tubes but didn’t best them overall. But if you were to ask me to evaluate the “Bang-for-the-Buck” aspect it’s no contest! Buy some of these and the adapter and you will be very happy. They are good enough that I’ve kept them in the preamps for everyday use saving the other tubes for those special occasions or weekend listening opportunities.
Thanks so much to Jim and Charles for opening this amazing avenue for us to enjoy fantastic NOS tubes for a fraction of the cost of the almost unobtanium premium 6SN7s.
Happy listening everyone
Stan
dunkmaster (verified owner) –
Bought a pair of RCA 6GU7 based on Jim’s video (Tube Lab) on YouTube. I am normally a Tung-sol 6SN7 fan, and also MELZ. I was extremely surprised by the sound of this tube. Warm, detailed and clean with a nice amount of resolution. Given the prices of my normal NOS favorites, it is a wonderful discovery to have some 6GU7 tubes as part of the mix, with no apparent loss of sound enjoyment to my ears. (I am using an R8 integrated amp, listening to all genres of music except rock. I also bought the 9 pin adaptor sold on this site….which are brass/ceramic and look great!
Rachael Warlond (verified owner) –
I, personally, didn’t particularly like the old or the new RCA, but the Sylvania and the GE – WOW!
Be prepared though, that while this tube is a substitute for the venerable 6SN7 and the Russian 6N8S, the sound, in general, is less warm, but this gives clarity a bit of a boost, which is a definite bonus. The Sylvania, once run in, is the warmest of the tubes mentioned here, but I would rate the Sylvania and the GE equally. Either tube comes highly recommended from me, especially given that really good NOS 6SN7/6N8S/1578 tubes are getting harder to find and more expensive. What have you got to lose – buy a pair (or two) – I promise, you will not be disappointed.
Rachael Warlond (verified owner) –
I also reviewed the Hitachi 6GU7 and of the 6GU7 range of tubes, in order, is the Hitachi 6GU7 AND the Sylvania 6GU7. If you favour detail over warm, buy the Hitachi, otherwise, if a little warmth is more of a priority, then the Sylvania is your tube.
Now, onto the 6CG7/6FQ7 tubes. The RCA cleartop is a winner. It’s very good everywhere, with amazing soundstage, however, if clarity/detail, including micro-detail is your priority, the little known Toshiba is a real “unicorn”. So much so, that I have just purchased another two pairs!
Rachael Warlond (verified owner) –
I’ve confirmed my favourite Japan 6CG7 are manufactured by Toshiba. While the RCA cleartop 6CG7 is a fabulous sounding tube, these Toshiba’s are almost a full level up. The micro-detail is fabulous, reminding me of the MELZ 1578 machine-gun plate in many ways. Of course, the Tosh 6CG7 do not have the warmth, but what they lack in warmth, they more than make up for in clarity and detail.
I’m about to order a pair of the Matsushita 6CG7 to see what these are like in comparison with the Toshiba.
Rachael Warlond (verified owner) –
This review is a little late, but here is what I found after buying the Matsushita 6FQ7. These tubes, apart from being a bargain (relatively speaking, especially when compared to NOS 6SN7s), pair very well with Matsushita’s own 12AX7 (R800i) or if you own an amp with 6SL7s (R8), then pretty much any of the Sylvania 7F7/6SL7 tubes.
The Matsushita are all about clarity and detail, so if you are looking for warmth, then it’s best to stay with a good NOS 6SN7 of which there are many good examples from Sylvania and Tung-Sol. Generally speaking, with 6SL7 & 6SN7 tubes, the later the manufacture, the less warm sounding will be the tube.
My personal opinion is that the Matsushita 6FQ7 is just slightly better than the Toshiba 6FQ7, although overall, it’s a very close call. As for the Matsushita 12AX7, my all time favourite tube has always been the Telefunken 12AX7, but given that these are now almost unobtainium (especially when it comes to finding a well balanced pair), the Matsushita is almost the Telefunken’s equal in so many ways, so I would say to you, that if you are having trouble finding the Telefunkens, then the Matsushita 12AX7 are a perfect alternative tube.