EAR Yoshino V20 Amplifier - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 16th January 2007, 07:38 PM   #1
poynton is offline poynton  United Kingdom
diyAudio Member
 
poynton's Avatar
 
Join Date: Mar 2005
Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)
Default EAR Yoshino V20 Amplifier

Hi.

Has anyone a circuit diagram of this amplifier?

Or a similar one using multiple small triodes?

Thanks

Andy
__________________
If it ain't broke, break it !! Then fix it again. It's called DIY !
  Reply With Quote
Old 27th January 2007, 04:44 AM   #2
poynton is offline poynton  United Kingdom
diyAudio Member
 
poynton's Avatar
 
Join Date: Mar 2005
Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)
__________________
If it ain't broke, break it !! Then fix it again. It's called DIY !
  Reply With Quote
Old 28th January 2007, 06:00 AM   #3
diyAudio Member
 
andrew_whitham's Avatar
 
Join Date: Oct 2005
Default another one.

I'll second this request. but I'd guess if anyone has these lurking anywhere they'd have been posted already

It IS an interesting way of doing things and I'm intrigued by it
Isn't "conventional wisdom" that lots of parallel tubes is naughty?Had it been any other designer....

so I've been a thinkin'

The website lists the tube complement as 26 (!) ecc83's and 4 ecc82's. Given is 5 ecc83's per side of each push pull output channel

Ok thats 20 tubes 10 triodes per half of the PP. But Ri for that combo is still around 6.5K, implying a transformer with a large turns ratio, another no, no

Oddly there's a review there that tells us that the Output tubes are set up to deliver 2.5watts each - huh? my datasheet says 1 watt max per section...

Then to quote the same online review elsewhere "A further five tubes per channel complete the line-up, including three more ECC83s for the input stages and a pair of ECC82 driver tubes."

ecc82's presumably as cathode followers to drive the input capacitance of the output stage

Then to take a complete flyer a mu follower (or similar) input stage and "differential" phase splitter.

Sound plausible?

I have a feeling that the OPT requirements effectively kill this approach for DIY, not sure though. 10 triodes ought to swing enough juice - 50-60ma at 300v for sure, but I'm figuring an OPT of the order of 40k - 50k here?!

Not quite similar but one of the tubecad journal's circuits fo the month is a headphone amp with multiple triodes. It is OTL though

Andy
  Reply With Quote
Old 28th January 2007, 06:04 AM   #4
diyAudio Member
 
andrew_whitham's Avatar
 
Join Date: Oct 2005
Default Owwww..

no sooner than I hit the button - I had a brainwave...

Could the output tubes be out of phase? one triode for each half of the transformer, you might be able to tap more power then. 2.5w from a "2w" tube?

Andy
  Reply With Quote
Old 28th January 2007, 09:57 AM   #5
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
You probably need to think near enough pure Class B, too. Possibly even B2 (that would lower the required output transformer impedance requirement).
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 28th January 2007, 10:22 AM   #6
diyAudio Moderator
 
pinkmouse's Avatar
 
Join Date: Apr 2002
Location: Chatham, England
I remember seeing it in a hifi shop in Hanover. Didn't get to hear it, but a very pretty piece of design.
__________________
Rick: Oh Cliff / Sometimes it must be difficult not to feel as if / You really are a cliff / when fascists keep trying to push you over it! / Are they the lemmings / Or are you, Cliff? / Or are you Cliff?
  Reply With Quote
Old 28th January 2007, 01:19 PM   #7
diyAudio Member
 
Brian Beck's Avatar
 
Join Date: Dec 2004
Location: South Florida, USA
Quote:
The website lists the tube complement as 26 (!) ecc83's and 4 ecc82's. Given is 5 ecc83's per side of each push pull output channel
Can someone please tell me why Tim De Paravicini used ECC83s as output tubes? Just to prove it could be done? Among common tubes, I can't think of a less likely candidate for an output stage than the ECC83.

But wait, why not take this concept further and use 100 nuvistors per channel?
__________________
Brian
  Reply With Quote
Old 29th January 2007, 02:30 AM   #8
diyAudio Member
 
andrew_whitham's Avatar
 
Join Date: Oct 2005
Doesn't make any sense to me either. Could be a typo/misinformation, I guess.

If you were picking tubes to do this with surely you end up with low Ri types (of course the ECC88 would be a favourite...)

I think I'll sketch this - it looks sufficiently like work I think

Andy
  Reply With Quote
Old 29th January 2007, 06:05 AM   #9
diyAudio Member
 
andrew_whitham's Avatar
 
Join Date: Oct 2005
Default Hmm

YEP! would love to see the schematic... wonder if its anything like the attached, probably not if theres 20 watts available...

I've run the numbers through TCJ's push-pull calculator and all I can come up with quickly is 10 watts for the 12AU7 (ECC82) thats at 300Va / 9ma / 1750 load

I guess that the ECC82 / ECC83 are reversed. I couldnt get any sensible figures for the ECC83 - not enough current.

And its at this point I'd drift towards bigger tubes - a similar number of 12SN7 gets around 16-17w straight away (400Va / 9ma / 2250 load)

I don't doubt that these could be improved, particularly if you're smarter than the average bear.

Actually there's a project right there, tough to beat that output with 0.7% third harmonic. Kind of makes a indirectly heated 300b

like I said Hmmmm

Andy
Attached Images
File Type: gif v20.gif (26.6 KB, 894 views)
  Reply With Quote
Old 29th January 2007, 09:09 AM   #10
poynton is offline poynton  United Kingdom
diyAudio Member
 
poynton's Avatar
 
Join Date: Mar 2005
Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)
Default Re: Hmm

Quote:
Originally posted by andrew_whitham


............. I couldnt get any sensible figures for the ECC83 - not enough current.



...........like I said Hmmmm



The reason I asked in the first place is that I have a box of twin-triodes at home (cannot remember the type but not ECC83/82/88 ) and I thought it would possibly make a good project.

Andy, Care to flesh out your schematic with some more numbers ?

Where is the TX available from ?/

Andy
__________________
If it ain't broke, break it !! Then fix it again. It's called DIY !
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
EAR / Yoshino 834T Tyimo Solid State 0 24th July 2009 12:02 PM
Wanted: DIY amplifier builder with experience. I need a 0.7 ohm stable amplifier Audiophilenoob Swap Meet 34 16th May 2005 11:58 PM
Questions about how to decrease the PASS A-40 amplifier into a class AB amplifier. novtango Pass Labs 2 21st October 2002 01:50 AM


New To Site? Need Help?

All times are GMT. The time now is 01:50 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2