To what facts this is based on ?
To "listening only" tests or to some measurements too ?
To what facts this is based on ?
To "listening only" tests or to some measurements too ?
To "listening only" tests or to some measurements too ?
Nobu K Shishido; who did a lot of work on Zero Bias tubes, recommends, low voltage high current.
Both the Grampian & the Gotham record cutting amp use Low 600 volts and high current, 70 Milliamps .
Phil
600 volts for 811A (as SE) is not anymore a low voltage. It is 40 % higer than 430 V, which is low in my classification.
If the starting point has been to find optimum bias for 3k5 OPT, then 430 V/ 100 mA can be understood.
According to my measurements few years ago best linearity was achieved with some 700...800 V as +Ub.
If the starting point has been to find optimum bias for 3k5 OPT, then 430 V/ 100 mA can be understood.
According to my measurements few years ago best linearity was achieved with some 700...800 V as +Ub.
Too bad,, I've been looking at all the 811SE schematics I could find,,, very few without interstage tx, SS controllers or in English...
The one I built may be the easiest, cheapest one, parts wise...
Regards,
John
Finally finished it!! Ended up using a paralleled 6SL7, 6BG6, and 811 per channel,,, didn't use FB, as experimenting with it showed no improvement...
Thanks to all the posters that helped along the way...
knckbill
i have built a lot of PP and single ended amps, you can get away without feedback, so long as your speakers are well damped; JBl 2220's Altec 515 and more otherwise the bass can be very bloated. One of my friends i sold a PP 811 to loves it without feedback; I find I prefer a little feedback. Have you measured the internal impedance? Will be very high with 811's and no feedback. Just depends what type of sound you enjoy. phil
Thanks to all the posters that helped along the way...
knckbill
i have built a lot of PP and single ended amps, you can get away without feedback, so long as your speakers are well damped; JBl 2220's Altec 515 and more otherwise the bass can be very bloated. One of my friends i sold a PP 811 to loves it without feedback; I find I prefer a little feedback. Have you measured the internal impedance? Will be very high with 811's and no feedback. Just depends what type of sound you enjoy. phil
It's based on the schem in post 6... with DC power supplies, and higher gain 1st stage...
Thanks Scott,,, I like wood work... finally picked up a nice old 10" bench saw, and rebuilt it last winter, my buddys GF, now wifes' family was throwing it out!!!!
I ran the signal generator waves thru this amp... they really looked about the same to me, just got bigger, as they went thru the stages, still would like to learn properly...
I like the sound of it, may not be perfect to some, tho....
I ran the signal generator waves thru this amp... they really looked about the same to me, just got bigger, as they went thru the stages, still would like to learn properly...
I like the sound of it, may not be perfect to some, tho....
That does look sweet. I ended up with a few 811a tubes that were given to me at a hamfest by an old ham operator when he found out what I was looking around for. Those are some really nice folks and I greatly appreciated his generosity. I've been looking to build something with them ever sense.
What is the power output and what is the current that you run through the opt? I plan on using Transcendar transformers so I would need to let him know what to wind for.
So why did you decide to go with parallel 6sl7 on the input instead of a 6sj7?
What is the power output and what is the current that you run through the opt? I plan on using Transcendar transformers so I would need to let him know what to wind for.
So why did you decide to go with parallel 6sl7 on the input instead of a 6sj7?
Hi Artosalo.
Do you still have this 811a SE Amp ??. I know it's more than 5 years since you posted the schematics..Have you tried the ryazan g811 in this amp ???
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.