Just wondering if anyone has had any experience with either one of these tubes. It looks like it might make for a fun experience. There is supposed to be a Russian tube available fairly cheap. I believe it is a GU13.
Any thoughts for a output transformer or circuit design?
Joe
Any thoughts for a output transformer or circuit design?
Joe
burnedfingers said:
Funny you should mention this, as I've been thinking about building an 813 parafeed amp because I have the components required spare and I thought it might be an interesting project. I've used this tube (and the GM70) in PP amps and they're great, especially at lowish voltages, ie 500-800V B+.
There are so many quality NOS 813's floating around the US cheap, that a GU13 is a waste of money. Buy some RCA/GE NOS. I have some STC CV26 / 813 that are the most beautiful tubes I own, but I only have 3 and I want to use them.
GM70's are a great sort-of-845 class tube, but there is the issue of non-availability of sockets.
Because the 813T and GM70 have higher mu, you need less drive voltage for them than an 845, so it's easier to design a good sounding driver. If you don't need the power, don't stuff around with the really high V designs, and keep it simple and sweet.
I built somewhat similar PP and differential versions of the design below, and they sounded awesome, but I didn't need the power they made, or the heat in summer. The driver tubes are about $2 ea and this was definitely better than a 6SN7-300B-813/GM70 design to my ears. EL84's would work too, and the pentodes are definitely the budget drivers to try.
http://www.pmillett.addr.com/813_se_triode_amps.htm
I used a linear tube rectified supply and tried both AC and DC heaters. For an SE, I'd just go DC.
An 813T has a plate resistance of around 1k8 so anything around 5k like a Lundahl LL1623/120mA, a One Electron UBT2 (B+ < 600V), an Electraprint or even a Hammond 1628 or 1629. Then there are the more exotic and expensive options....
Hi Joe
Some god points from Brett, there.
I use triode coupled 813s in single ended amps
for midrange and treble. Sounds ok to me.
I have used the 845 too, but prefer the 813 for midrange.
Stay with simple 2-stage amps if you can.
I use DC for the filaments.
cheers 😉
Some god points from Brett, there.
I use triode coupled 813s in single ended amps
for midrange and treble. Sounds ok to me.
I have used the 845 too, but prefer the 813 for midrange.
Stay with simple 2-stage amps if you can.
I use DC for the filaments.
cheers 😉
Thanks for the link. It looks like a very interesting design to try. Any good sources for the 813 tubes? Brett did you use the 12HG7 driver in yours? I think I will look thru the old tube box to see if I have anything interesting in there that would work otherwise I will pop for some 12HG7's. The first go around will have to be with cheap iron(sorry Frank)
if I like what I have I will pop for some good iron. After all the Hammonds can always be reused on other projects.
Joe
if I like what I have I will pop for some good iron. After all the Hammonds can always be reused on other projects.
Joe
burnedfingers said:
Just check around the dealers online. Because they're a radio tube, some commercial suppliers have them at good prices. Maybe $20-25 ea
Yep. Also the 12GN7A (the one I stuck with), 12HL7, EL84
Brett
Would you care to share a schematic? I am also interested in a PP version but haven't found a schematic.
Joe
Would you care to share a schematic? I am also interested in a PP version but haven't found a schematic.
Joe
I've always liked this one: http://www.balstudio.com/813/813page1.htm
What's the story on using electro caps with balance resistors for filtering in terms of life expectancy? not necesserially your own but theirs =)
Btw pmillet's link is dead: http://www.pmillett.addr.com/813_se_triode_amps.htm
What's the story on using electro caps with balance resistors for filtering in terms of life expectancy? not necesserially your own but theirs =)
Btw pmillet's link is dead: http://www.pmillett.addr.com/813_se_triode_amps.htm
Not dead, just moved:
http://www.pmillett.com/813_se_triode_amps.htm
Curious what this thread turns up. I have a pair of Chinese 813's waiting for a plate transformer enroute.
http://www.pmillett.com/813_se_triode_amps.htm
Curious what this thread turns up. I have a pair of Chinese 813's waiting for a plate transformer enroute.
I also have a bunch of 813 and most of the parts needed to build an amp.
Until recently I´ve been aiming for 27W output (A2 at peaks), but I think I´ll settle for pure A1 operation instead because of the attractiveness of a simple two stage design.
My PSU is set to about 900V, so I must choose between grid bias (higher power) or cathode bias (80 V drop across the resistor).
Until recently I´ve been aiming for 27W output (A2 at peaks), but I think I´ll settle for pure A1 operation instead because of the attractiveness of a simple two stage design.
My PSU is set to about 900V, so I must choose between grid bias (higher power) or cathode bias (80 V drop across the resistor).
Re: Re: 813 or 845 for a SE amplifier
What of the James transformers are suitable? Would I be right in assuming that all SE James trannies have a max insulation voltage of 1kV?, I'd like to consider picking up the 813 project again and utilise a comple of these, The issue that prevented me from constructing it last time I was here was the cost of transformers...ie the only suitable transformers were Tango or Hammond and I wasn't paticularly keen on Hammond.
Suppliers of James tranies at Octave electronics and Bella audioparts
(no affiliation)
Brett said:
What of the James transformers are suitable? Would I be right in assuming that all SE James trannies have a max insulation voltage of 1kV?, I'd like to consider picking up the 813 project again and utilise a comple of these, The issue that prevented me from constructing it last time I was here was the cost of transformers...ie the only suitable transformers were Tango or Hammond and I wasn't paticularly keen on Hammond.
Suppliers of James tranies at Octave electronics and Bella audioparts
(no affiliation)
Pete Millett had success with a 5k so I'll try my JS-6123H first. The plate transformer for this project has straps for 3000, 1500 and 1000 CT. CL or LC combinations provide enough voltages options to start low and work up slowly.
But you're right, nowhere does there seem to be any mention of James' max operating voltage. It's got to be a relatively safe bet though that the models spec'd for use with 211's and 845's will hande an 813.
Edit: Dropped the manufacturer and e-mail inquiring about this. Their home site is: http://jianshin.myweb.hinet.net/english_first.htm
But you're right, nowhere does there seem to be any mention of James' max operating voltage. It's got to be a relatively safe bet though that the models spec'd for use with 211's and 845's will hande an 813.
Edit: Dropped the manufacturer and e-mail inquiring about this. Their home site is: http://jianshin.myweb.hinet.net/english_first.htm
rdf said:
Actually I didn't mention it before but euphonia audio do provide the datasheets for three of James's transformers and they do all state that their max insulation voltage is 1kV AC at infinite ohmage, just click through to the item's individual page and there are .pdf files linked on their pages, however as euphonia only sell the 6130HS, 6133HS and 6159HF in Orient HiB, I decided to leave the issue open as I'm unsure in speculating the breakdown voltage for the JS-6123H.
Indeed it may just be that way, anyone wishing to further enlighten us death wishers on the issue? 😀
And I'll dig around on their website, maybe I can find something in Japanese and then translate it...
Layberinthius said:
Nope, no further specifications to speak of other than what you get on the english version of the site.
This morning's response from James:
Helpful and prompt response, if an expensive one. Now it has me wondering about the way James rates current, 120 ma should have been sufficient. Looks like I need new iron in any case. 🙁 Might be a good opportunity to give the re-vamped Hammond line a shot. Maybe the 1629SEA?
Helpful and prompt response, if an expensive one. Now it has me wondering about the way James rates current, 120 ma should have been sufficient. Looks like I need new iron in any case. 🙁 Might be a good opportunity to give the re-vamped Hammond line a shot. Maybe the 1629SEA?
Re: Re: Re: 813 or 845 for a SE amplifier
Probably building an SE 813T for a customer as a guitar amp.
Based solely on looking at the spec list on the site you linked, the -6123, -6135, -6157. Never used any of them so I have no idea of the sonics.Layberinthius said:
No idea. Ask the manufacturer/distributor.,
There's also Lundahl, which are very good transformers though often overlooked as they're not 'boutique' enough. There's an Aussie distributor, but he'll probably have to order them in. Good guy to deal with.
Probably building an SE 813T for a customer as a guitar amp.
Re: Re: Re: Re: 813 or 845 for a SE amplifier
Already asked them, seems they're only suitable up to 500v.
"Sorry,the JS-6123HS is used EP voltage 400v~500v.That suit to vacuum tube
for 300B,2A3,6V6,KT88 .
So you can not use the JS-6123HS in 813 amp.
The JS-6123HS's ib current could not reach the tube of 813's standard.
We attach the 813's data sheet for you reference.
Could we know where the country do you come from?
JIANSHIN ELECTRONICS CO.,LTD"
- Courtesy of rdf
LL1620's max voltage is for PP operation, SE being 380v...
LL1688 also comes close, being rated for 845's:
Afaik Lundahl don't do customs, but this may be the ticket, if only they can up the max primary voltage to about 850-950v from 530v.
I wonder how pricey a custom transformer from Sowter would be? suited to the task.
You might need to stick a note on the front saying "For fear of electrocution, don't ever bloody kick it!" 🙂
Brett said:
Already asked them, seems they're only suitable up to 500v.
"Sorry,the JS-6123HS is used EP voltage 400v~500v.That suit to vacuum tube
for 300B,2A3,6V6,KT88 .
So you can not use the JS-6123HS in 813 amp.
The JS-6123HS's ib current could not reach the tube of 813's standard.
We attach the 813's data sheet for you reference.
Could we know where the country do you come from?
JIANSHIN ELECTRONICS CO.,LTD"
- Courtesy of rdf
LL1620's max voltage is for PP operation, SE being 380v...
LL1688 also comes close, being rated for 845's:
Afaik Lundahl don't do customs, but this may be the ticket, if only they can up the max primary voltage to about 850-950v from 530v.
I wonder how pricey a custom transformer from Sowter would be? suited to the task.
You might need to stick a note on the front saying "For fear of electrocution, don't ever bloody kick it!" 🙂
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