Did you get to try them? How do they sound? Are 6C8G and 6F8G tubes worth to try? They seem to be cheaper than their 6SL7 and 6SN7 counterparts.
You should try adjustments of feedback first. It significantly change the sound. Having pre-amplifier with tone controls helps too - many records require rolling off EITHER treble of bass to sound comfortable.
I had not played RCA vt229 Jan and Kenrad vt229 for a while maybe more than 2 years. Thus I had decided to insert RCA vt229 after Russian 6n9s made in 50's. RCA vt 229 give very transparent and 3 D holographic sound with deep soundstage and sharp focus. Overall it is a very nice tube for the price ( you can get one around 50$ from Ebay). But I still prefer 6n9s to RCA vt 229 with RCA 805 due to sweet treble and air. Then I had gone to RCA 5691 red base to compare with RCA vt229. RCA 805 and RCA 5691 does not have good synergy with too vivid sound clost to hot. I had good experience with Acme 805 and RCA 5691. Thus RCA 5691 may work in dark or neutral sounding system while mine is on the revealing side. After I try Kenrad vt229, I will report again.
I am listing to Kenrad vt229 now. It sounds similar to RCA vt229 but with fuller bass like Kenrad vt231. Kenrad must have house sound of good bass. Overal balance is quite good to my taste. I am going to play it for one day and then be back to Mullard ECC35. About one week ago Mullard ECC35 sounds musical with nuanced texture but hazy soundstage compared with RCA or 6n9s. It is like wine tasting. After you change the tubes, it looks as if you had changed your pre amp. LM 508 or 805 is a dream amp for tube roller. But because of that, I had spent 12k$ on tubes during last 3 years. I am using some of 6sn7 tubes on Schitt Freya pre in my headphone chain.
Sorry to hear about your rib fracture, Pedro. Hopefully they are healed by now! Glad to hear that aside from music and hifi we also have some a common outdoor hobby. It is great and healthy and the active exercise balances out the time we sit in front of the speakers. I just need to learn to stay upright on the bike.
Let see if I understand correctly. 6C8G tubes are not direct replacement for 6SL7? It would diminish the gain on the amp? If that's correct, I've read somewhere that 6C8G tubes sounded bigger and more alive that 6SL7. How is it possible? What about 6F8G tubes? Some guys on another forums prefer them over their 6SN7 counterparts. Has anyone have experience with 6F8G tubes? Are they safe to use on the LM-508? Some of them are pretty cheap here in my country. So, if it's safe to try, it wouldnt be a big expense to try them on.
Ok. I stand corrected. I was just purely looking at the amplification factor. But with all other components, approx, in the 508IA, the 6SL7 has 3dB more gain than the 6C8G. Which is not that much. It may or may not be significant as u can just turn up the volume a bit more with enough headroom.
Feedback unfortunately affect both high and low frequencies. only at position 2 is the best of the bunch. I have tried EQ but it seems to hurt more than help. Last evening I added some extra absorption panels to some bare walls and it seems to tame it. My room is especially live and even with a dozen large panels I might need to put up some more.
I had also settled to No 2. position after lot of experiment during 3 years of use. It gives nice balance.
To all gentlemen who own RCA 805. Does your tube have denotation like Jan vt 143? I had been playing RCA 805 made in 60's without such denotation two weeks. It sounds very transparent but with lean balance so I had matched it with warm sounding 6sl7 tubes. Today i got another pair of. RCA 805 with Jan vt 143 made in 40's. I will give my impression of tube after few day's of cooking. But it sounds somewhat different from the ones made in 60's in maybe good way (not so lean).
Took a long while but I got my Mullard ECC32s today. I'll give a tone report in a week once I have thoroughly tested them.
Is your RCA 805 military version with Jan vt 143 engravement? I found that RCA with it or not sound different. But I will wait until I get enough burn in time with new tube.
It doesn't have any date codes on it. If I had to guess, it's from a more recent production batch later than the 40s.
My tube has date code of March 1943. It keeps changing sounds after burn in. I do want to reach hasty conclusion. By next week end, I may give opinion on it.
mine is Aug 1942 with serial S18993. and another S11477. For those who don't have a date stamp, it is possible to interpolate to find it. After A/B comparing with other tubes, and then comparing with different DACs and amps, I found the RCA 805 while provide good dynamic and clarity, they are a bit aggressive in sound. In fact, going back to Cossor the Cossor provide a better balance overall but clarity is not as good. My speakers are a bit to the energetic end of the spectrum. Plus the ears are getting older and I am leaning towards not using the RCA 805 for now. In the end, it is all about synergy with the rest of the system, source, speakers, room and also the ears.
I tend to agree with this description, however in my system which is fully tubed from DAC ---> Linestage ---> amp and then going to DeVore O/96's those qualities in a power tube aren't a bad thing. As with most things audio, it's very system dependent.
I feel that specific power tube sound is not universal quality, but depends on speaker used with amplifier. With some speakers tube can sound bright, but with other - dull. That means one cannot assume how tube will sound in specific setup based on other's experience. Which leaves us with personal trial and error excersise: bad for audiophile's budget, but good for tube sellers.
my understanding is that each component has a certain bias in sound, some are brighter, etc, I can tune a tube DAC/Amp and even speakers with different component. A system with a bright tube can be made warm if the remaining components are sufficiently warm to counter the brightness. So in the end, it comes down to the right balance and blend of material used. Even tube, can be made very bright or warm that way.
