EAR Yoshino V20 Amplifier

[andrew_whitham]

How do you get that output from ECC83's???

You dont. at least not in anyway I can see (which isn't saying much) but you can get it from ECC82's

Problem is ECC83 / 12AX7 has Va Max of 300v and Ik max of 8ma the ECC82 OTOH is Va Max 300v but Ik is 20ma rating at 2.75w

I can't get it to come with any sort of compromises I'd willingly take on. Its simpler to do it with the 12AU7 / ECC82. I *must* be missing a trick.

What is "Tim’s highly developed Balanced Bridge Mode ultra-wide-bandwidth output transformer"?

Marketing.... "highly developed" 🙂 who would claim otherwise?

I wonder if balanced bridge is another way of saying distributed load? a la Quad 2? Somewhat different to what I've drawn. Its equally possible that the thing is completely off the wall

I believe so, if just barely. The idea of running 12AX7A into the grid current region of operation is disturbing..

Indeed, I ran like a scared puppy, disregarding that restriction (and Peak Ik to some extent) you can get 20 watts with the grid at +4v

As asked, I've fleshed out the schematic I was tinkering with, please note this is the result of a simulation rather than any serious soul searching.

(incidentally I recommend the P-P calculator for this, its a sight easier than actually thinking about it...)

Andy

 

[netbug]

So did this schematic ever get built? This looks like a fun project.

 

[Tubes4e4]

Hi Andy,

This was elsewhere on the forum.
Similar to half of andrew_whitham's circuit.
http://www.geocities.com/freespeedpro/1W-se.jpg

Just for the record, the schematic you linked is from Mr. Klaus Boehm, Cologne, Germany. Almost a decade ago he ran a very nice tube DIY web site, excellent graphics, photos, layout, articles, etc.

Regards,

Tom Schlangen

 

[EC8010]

I wonder if balanced bridge is another way of saying distributed load?

Yes, it is. More of a McIntosh than a Quad II because Tim de P uses equal loads in anode and cathode.

 

[DrewP]

I seem to recall reading that Tim had some of the output transformer windings on the cathode side as well as the anode side of the tubes. I suppose if you floated the grids to about 1/3 of B+ with a cathode resistor and a bypass cap and then had your transformer windings in the same place that you would normally have the load resistors on a Concertina phase splitter you could have a lot less voltage across the tubes.

Have the HFNRR article somewhere where KK gave (in typically wooly KK fashion) his understanding of how the output was configured. Wasn't enough to understand what was going on though.

 

[as_audio]

EAR Yoshino V20 schematic here :
https://www.diyaudio.com/forums/tubes-valves/362071-ear-v20-schematic.html#post6579515