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anyone tried comparing 807 and 6L6 in terms of sound characteristics? (on the same amp preferably)
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I have tryed both 6l6gc from GE. 5881WXT from sovtek and 807 in a push pull with UL tapping. and they all sound different. so if you have the sockets on your amp and only need some reviring you should try it. I liked the sound of the 807. they have a tighter and betther bass.
So GO FOR IT.
tyor
I had a pair of heathkit wm3's that I converted to 807's. The only real change was the tube sockets, so they were running at the same operating points. I used them with a pair of vandersten 2c's for about a year. Sound was comparable with both tube types but I liked the look of the 807's with the tall profile and plate caps.
VERY unlikely that anyone would have a single amp that could use both tubes; 6L6 is a standard octal, 807 uses a 5 pin base and an anode cap,-- serious experimenters only. That said, I also don't really think there is an "807 sound" or even a "6L6" sound. Yes, the 6L6 family is said to have nice bass, "pronounced, forward midrange" etc. etc etc, yet a lot of what is heard is the AMP, interacting with the tubes, not the tubes themselves. Many will disagree; Then, of course, there are folks with opinions on tubes they have never heard..... :0) Here is what is absolute about 6L6 and 807: they are beam tetrodes. The 807, in VERY loose terminology, is a sort of "super" 6L6 (or "baby" 6550!) Early versions of 6L6 like 6L6G, 5932, etc are wonderful tubes-- the black glass Sylvania and TungSol 6L6G are among the finest beam tetrodes ever made. Unfortunately, they are critically hobbled by max DC ratings of 360 VDC plates (some do 400 VDC) and just 270 volts screens; these tubes must be run either in true tetrode or with a tertiary-wound transformer to get any real power out of them. Ditto for the 807, except that the plates will take nearly 800 volts.... the screens still are locked down at 350 VDC max. This seriously limits their usefulness because running them in tetrode, like in the Altec 256C, requires complex power supply regulation schemes for the screen supply. In class B, with 675 VDC plates and 300 VDC screens, a pair of 807s makes a LOT of power quite gracefully. There are several dozen variations of each, each with a slightly different "flavor", produced not by that tubes' "sound" but by the interaction of the tube and its' application. If you do not need a lot of power, or are prepared to use the Sowter reproduction of the Acrosound TO350 w/the tertiary winding for the screens, both tubes are a hell of a bargain because most folks skip over them due to the above limitations. Probably the single best tube value going anywhere is a 1940s 1625; it's an 807 with a 12 volt heater-- I routinely see NOS Milspec Sylvania and "Hytron" 1625s for about $5 each! This, for a tube that will absolutely thrash any $400 quad of XF2 Mullard EL34s ever made! The tertiary transformer is the way to go; it uses a truly independent winding for the screens, not just a screen tap on the plate winding like in Ultralinear. This allows much lower voltages to be used on the screens than the plates, while still maintaining tight reign on the screens unlike in tetrode. Tim Di Pavricini, in his TOO COOL E.A.R./Yoshino designs uses the magic of tertiary to use his "pet" tube, the EL509, much like the way an 807 could be used; with less than 200 volts on the screens and big DC on the plates. Those EAR amps are the hottest thing to come around since WZ Johnson rolled out the Audio Research D52 back in 1974. Anyway, for all practical purposes 6L6 compared to 807 is apples and oranges. Both great. Both beam tetrode. Otherwise quite different.
Excelent post! And yes, you are correct in stating that the 807 can be run with over 450 volts on the plates (600) in push pull AB1 mode. But the screens must be at 300 volts. 10K PP load, 2.2% THD at 47.5 watts. Not bad! See the link below: http://www.retrovox.com.au/STC807.pdfI like your ultralinear mode with tertiary windings idea. Should lower the effective Rp. By the way, Lundahal also makes a suitable transformer - the 1679. Here is a link: http://www.lundahl.se/typelist.html
Just a couple of minor points: Regardless of how much power they're putting out, I don't know too many people that would opt for a class B amp. Both 807's and 6l6's will sound like crap in class B. Secondly the only way you can put nearly 800Volts on an 807 is in Class C RF use.
The 807 and 6l6 in AB1 PP work at very similar operating points and put out the same power. ie 450Va 400Vg2 approx. 140mA into 5600ohms for 55watts out. This is straight off TDSL. You can run 807's hotter than a 6l6 but it doesn't improve the sound from my personal experience.
thanks for the facts.actually have an amp that can take on both 6L6GC and 807 with some wiring mod. thought of getting advance info on what to expect (and if worth trying)...
where does the 6146 fit in the scheme of these other tubes?
tubelover, elektron is correct. the 6146 is a tube used for RF service. I have a linear amplifier that uses four of them. They work great for transmitting radio frequency (CB or Ham) waves, don't know about audio service.I would imagine that one would have to use grid #2 for the "control grid" just like in a 6KG6 (or simular **sweep** tube like a EL509). Go to Svetlana's web site and down load the free scematic for the EL509 amplifier. Ron
6146 is an RCA Radiotron design introduced in the mid 50's about the same time as 2E26, if memory serves. 6146 was primarily an RF device although there were orders from "on high" to use the tube for audio and it was mandated ( there's that word again ) for use in audio amplifiers. The audio engineers were not happy with the edict, but had to do as they were told. 6146 exhibited problems in service, unstable bias being chief. 6146 was really much better suited to RF service where it performed well. The concept of "one tube does all" just didn't work and was probably driven more the notion of selling more tubes. RCA retrofitted amps using 6146 with 6550 ( a TungSol device ) that was also introduced in the 50's along with 5881. Perhaps RCA was jealous of TungSol's success with 6550 & 5881. After all, RCA was a whole lot bigger than TungSol.
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