World Audio single ended 4W questions
Tomek Jarosinski
I have a possibility to buy one 6 years old World Audio DIY single ended
tube integrated amplifier. But the output tube is not there ! This
amplifier has three 6922 in the preamp section and one big valve in the
output section. Does anybody know what kind of valve it is ? Maybe
somebody has a schematic and description for this amplifier ?
Cheers, Tomek
PS You can mail me directly, if you like
PAM
www.worldaudiodesign.co.uk
Tomek Jarosinski skrev i meddelelsen <3BEB95BB...@is.fh-hamburg.de>...
RdM
I have in front of me the Hi-Fi World Supplement No.6 1993.
Cover photo & int article of 3x ECC83 1x 6080 4W SE stereo amp -
designed by Tim de Paravicini, written by Noel Keywood.
Distortion 4W 3%, 1W 1.2%, most of that 2nd harmonic ... (0.1%3rd)
"Bass a little light ... " you'd have to read the whole thing.
4 A4 pages in article. 5 plus cover.
I have a photocopier, and could send you hard copy in a week or so,
but could also fiddle about and <Bin Meaning To> try to reverse scan
via a fax machine to the PC ... no actual PC scanner here yet ... in a
day or so I suppose if that worked out OK. Try me, nz not zz, maybe.
Meanwhile, perhaps the above will assist for a starting reference.
I'm not sure if there was a follow-up to this article, anyone else?
Ross Matheson
RdM
>BiNG!!!
>
>I have in front of me the Hi-Fi World Supplement No.6 1993.
>
>Cover photo & int article of 3x ECC83 1x 6080 4W SE stereo amp -
Sorry, that was 1x ECC83 and 2x ECC88, & 1x 6080, as per original.
ECC88 = 6DJ8.
(6922=E88CC.)
Maybe someone has swapped some valves around?
6080 was your low-mu twin power triode output device, anyway.
RdM.
Russ Sadd
> I have a possibility to buy one 6 years old World Audio DIY single ended
> tube integrated amplifier. But the output tube is not there ! This
> amplifier has three 6922 in the preamp section and one big valve in the
> output section. Does anybody know what kind of valve it is ? Maybe
> somebody has a schematic and description for this amplifier ?
Hullo,
The big valve is a 6080. This is a power double-triode used in
regulated power supplies. The 6080 is the more 'modern', metal-skirted
version, but you can also get the 6AS7G which is in a nice 300B-like
shouldered bottle.
From what I remember, Tim de Paravicini designed this amplifier, but
for some reason, Hi-Fi World pulled it from its catalogue very
quickly. I guess it's a very rare Hi-Fi World amp for that!
I could certainly find you the original article, but you'd have to
wait until January (I'm working in Germany at the moment) - I'm sure
someone else can dig it out for you. What I remember, however, is that
both triodes of the 6080 were used independently as single-ended power
amplifiers, and the ECC88s were used to raise the necessary voltage
gain. I would imagine that it used loop feedback, as otherwise the
gain stage would seem rather excessive.
Hi-Fi World reviewed it favourably at the time (not exactly an
unbiased viewpoint, though!) and the design didn't seem off to me. It
struck me as a rather nice thing to try, and I eventually ended up
building a push-pull version of my own to see how the 6080 performed
(rather well, too!).
Best regards,
Russ Sadd
New valve audio site at http://members.tripod.co.uk/griffonconsulting
Skrewball
I have some 6080's here that I have been *itching* to use in something!
Do you have a schematic of your amp Russ?
Does anybody have a schematic of the 4w amp?
I have a PP 3.5K transformer here,I was thinking of running 2,or 3
6080's in paralell,just to try it out. Any ideas?
Thanks! Patrick.
Ross Matheson
Skrewball <pta...@qwest.net> wrote:
>This sounds like an interesting circuit.
>I have some 6080's here that I have been *itching* to use in something!
>Do you have a schematic of your amp Russ?
>Does anybody have a schematic of the 4w amp?
I have the original Hi-Fi World Supplement No.6 1993.
I am intending to scan and make available in 24hrs or so ~
Ole, aloha, aroha;- over the weekend:
I'll be back.
R.
RdM
ste...@zfree.co.zz (Ross Matheson) wrote:
>>Does anybody have a schematic of the 4w amp?
>
>I have the original Hi-Fi World Supplement No.6 1993.
>I am intending to scan and make available in 24hrs or so ~
This includes the circuit, parts list, discussion, review, etcetera.
There was a picky let/resp in Sup 7 over a minor detail I'll include.
Not sure if there was anything further yet, - don't think so ... (?)
I'm happy to email it when done;- to those few specifically into it.
(I don't have a web page at this point but it is on the to-do list :-)
I note that alt.binaries.schematics.electronic exists, but it is
busy? enough that folks may not be that keen to monitor IMO, so I'd
probably send a copy to Uncle Ned's mailbag for best posterity,
howzat? Or any UK/EU host. Is this fair dealing in a copyright sense?
I'd be happy with it. Wot about Hi-Fi World? Anyway, let's scan first
RdM
{it's not even at mo' my cup of tea, SE, -but in t' spirit of sharing!
RdM
ste...@zfree.co.zz (Ross Matheson) wrote:
>>Does anybody have a schematic of the 4w amp?
>
>I have the original Hi-Fi World Supplement No.6 1993.
>I am intending to scan and make available in 24hrs or so ~
This includes the circuit, parts list, discussion, review, etcetera.
RdM
ste...@zfree.co.zz (Ross Matheson) wrote:
>>Does anybody have a schematic of the 4w amp?
>
>I have the original Hi-Fi World Supplement No.6 1993.
>I am intending to scan and make available in 24hrs or so ~
This includes the circuit, parts list, discussion, review, etcetera.
Tim
> 6080's in paralell,just to try it out. Any ideas?
Nick once sent me a schematic of an OTL that uses +-150V and 3 6AS7s.
Must be good for what, 200W?
Seems to me that if 3 sections in parallel can push that low an impedance...
Tim
--
"Kill my boss!? Do I dare live out the American dream?"
- Homer Simpson
Dave Cigna
"Skrewball" <pta...@qwest.net> wrote in message
news:3BED0AD9...@qwest.net...
> This sounds like an interesting circuit.
> I have some 6080's here that I have been *itching* to use in something!
> Do you have a schematic of your amp Russ?
> Does anybody have a schematic of the 4w amp?
>
> I have a PP 3.5K transformer here,I was thinking of running 2,or 3
> 6080's in paralell,just to try it out. Any ideas?
>
> Thanks! Patrick.
>
Sounds like a cool project. Just remember what makes the 6080 special: it
has very high transconductance and VERY low plate resistance. (What'ya
expect? It's a regulator tube.) Anyway, to get the most power out of it you
need to use a very small load resistance and run it hot; something like 75
mA at 150 volts into 600 ohms (for example.) This should provide four watts
from each section. With three tubes (six sections) in class A parallel
push-pull this is 450 mA with a 200 ohm load!
Your 3500 ohm pp transformer presents a load of 3500 / 2 = 1750 ohms on each
side. If three sections of 6080 share this load they will see 1750 * 3 =
5250 ohms each. This should work fine. In fact you get to run them a lot
cooler - maybe 30 mA per section - so your output transformer might not blow
up. :) The bad news is that you won't get 24 watts total. I'm thinking
something like 1.5 watts, but it might be 1.5 really good watts!
I hope all of this doesn't sound discouraging, I don't mean it to. I've got
a mess of 6080s myself that I'm itching to use, and I've considered a mess
of possibilities but haven't done anything with them yet. I'm eager to find
out how your project goes, if you do it.
-- Dave
p.s.: Some of the 6080 plate curves that I've seen are a little fishy: the
current axis is labled 25, 50, 100, 125, 150, ... Where's 75?
RdM
OK, I have had a session at a friends house with a scanner and now
have the 4 pages of the original article (incl. circuit, parts values,
etc) and a 5th page from the next supplement with a related letter
(that was hardly worth including really but I have now, anyway)
End format is a 5 page PDF file. It's quite clear and very printable.
Unfortunately this weighs in at 744 KB (not too bad via modem though)
In addition, and separately, because for some reason the .pdf page
would have been about 3 MB, I've made a JPG of the cover (ie a colour
photo of the amp), which is 167 KB. Zipped together, total 904 kb.
(there's virtually no compression left to be had in zipping, 1-2% max)
I left the black and white additional photo off the PDF off the first
page, so that I could keep the whole thing in B&W text format and the
filesize down (again, it would have made the pdf much bigger), so the
colour supplement cover photo is the only picture of the finished amp.
The transformers, BTW, were custom designed and wound, and no details
are given for them.
Since I have no web page up or place organised to upload this, I'm
just proposing to email it to the original poster at this point, if he
still wants it (let me know!), and maybe Skrewball, since he expressed
interest. I'd really rather only do this once and Cc it, as I can
only upload at 33.6k via modem, so if anybody else is *seriously*
interested, say so and I'll consider alternatives, or add them in Cc.
I suppose I could try an upload of the .pdf to a.b.s.e .
Sorry about this, but I've come back after a period away, and I have a
lot of organising to do before I get around to web pages and the like.
Strangely, I have little or no interest myself in low power SE amps,
it's just that I had the article - must be the ex-librarian in me!
Ross Matheson
(in nz, not zz!) (Spam block)
(Or email more directly to stereog at ihug dot co dot nz)
(the zfree address is webmail and checked less frequently)
On Fri, 09 Nov 2001 08:37:15 +0000, Tomek Jarosinski
<to...@is.fh-hamburg.de> wrote:
LiloLee
put up a link.
Lee
Tim
> have the 4 pages of the original article (incl. circuit, parts values,
> etc) and a 5th page from the next supplement with a related letter
> (that was hardly worth including really but I have now, anyway)
Ah, excellent. You can add me to the CC list, or (preferrable, as
bandwidth is concerned) give it to LiloLee and let'm upload that..
I'm happy enough to wait for a link.
BTW, last night you said something about an induction heater...
avisg...@gmail.com
johnn...@gmail.com
http://www.diyaudio.com/forums/tubes-valves/293249-thinking-outside-box-triode-audio-amplifier.html
Cheers to all, John L Stewart