I've seen only the 3rd edition. And it alluded to another book as-if
they might be a set? The book I saw (in basement library at UTA)
was almost entirely practical wisdom in regard to constructing and
testing the amplifier, and had very little on valve circuit theory.
I don't recall seeing any KT88 schematic, but my time with the book
was brief. I was not an enrolled student, so checking the book out
or obtaining a photocopier account wasn't really an option.
It was definitely titled Morgan Jones' Valve Amplifiers...
TK7871.58 A9 J66 2004, if it might help you finding it.
Edition I found was at Neederman Hall, not the main UTA library.
I was only there for one week of National Instruments training...
And its over now, but mabey someone else lives close to UTA
could check into it further.
they might be a set? The book I saw (in basement library at UTA)
was almost entirely practical wisdom in regard to constructing and
testing the amplifier, and had very little on valve circuit theory.
I don't recall seeing any KT88 schematic, but my time with the book
was brief. I was not an enrolled student, so checking the book out
or obtaining a photocopier account wasn't really an option.
It was definitely titled Morgan Jones' Valve Amplifiers...
TK7871.58 A9 J66 2004, if it might help you finding it.
Edition I found was at Neederman Hall, not the main UTA library.
I was only there for one week of National Instruments training...
And its over now, but mabey someone else lives close to UTA
could check into it further.
You're right, I didn't think that far. However, I'd be happy just to have a look at it directly (not posted) as I'm curious and it's for educational purposes, which is legal here to the best of my knowledge. I have purchased both BVA and VA - 3.SY said:
However, I will respect Morgan's wishes either way.
Many thanks to Morgan for granting permission.
I would be most interested if Morgan could kindly supply any further details; what transformers, etc.
I have attached both versions, from the 1st and 2nd editions of his book.
I would be very interested to see the power supply for this amp!
Also included the GEC '88-50' for info (circuit freely avaialble)
I was thinking of building an unbalanced version.
I would be most interested if Morgan could kindly supply any further details; what transformers, etc.
I have attached both versions, from the 1st and 2nd editions of his book.
I would be very interested to see the power supply for this amp!
Also included the GEC '88-50' for info (circuit freely avaialble)
I was thinking of building an unbalanced version.
Not hard to spot as one of his designs. Looks quite solid, and I'll bet that a 6SN7 would do beautifully for the driver tube. As with any similar cathode-bias design, blocking on overload can be an issue, which is probably why he added the cathode followers to the Crystal Palace. If you're going to this trouble, I'd just duplicate the CP driver stage, and substitute the KT88 and appropriate output transformer- it's only slightly more complex.
Thanks for your replies, chaps.
I hadn't thought of subbing the Crystal Palace driver stage; an interesting thought. But looks more complicated than this.
I like the idea of Morgan having updated the GEC circuit with E88CC, EF184 and E182CC.
Another point is I've got loads of these bottles to hand.
I was thinking of re-jigging the E88CC to unbalanced..................
But the power supply puts me off a bit; having to provide both 700V and 500V.
Perhaps you wouldn't mind asking Morgan about his power supply.
Many thanks!
I hadn't thought of subbing the Crystal Palace driver stage; an interesting thought. But looks more complicated than this.
I like the idea of Morgan having updated the GEC circuit with E88CC, EF184 and E182CC.
Another point is I've got loads of these bottles to hand.
I was thinking of re-jigging the E88CC to unbalanced..................
But the power supply puts me off a bit; having to provide both 700V and 500V.
Perhaps you wouldn't mind asking Morgan about his power supply.
Many thanks!
I'll drop him a note.
The CP driver stage is more complicated only in that there's a couple of cathode followers added. They are an important element in making the design robust against blocking distortion. I hope that I am betraying no confidences by saying that he was not entirely pleased with the earlier designs, which is why they were dropped from VA3.
The CP driver stage is more complicated only in that there's a couple of cathode followers added. They are an important element in making the design robust against blocking distortion. I hope that I am betraying no confidences by saying that he was not entirely pleased with the earlier designs, which is why they were dropped from VA3.
From Morgan:
"The design was only there to show how balanced feedback and input might be achieved. It was more of a didactic tool than a full design. I'd use whatever is in stock, but a big heavy choke would almost certainly be needed to keep hum under control and avoid nasty little 100Hz sidebands at full power. I'd very much like to see a Quad II full power distortion spectrum - I suspect it wouldn't be nice at all and together with the anaemic output transformer would explain the soggy bass with electromagnetic loudspeakers."
"The design was only there to show how balanced feedback and input might be achieved. It was more of a didactic tool than a full design. I'd use whatever is in stock, but a big heavy choke would almost certainly be needed to keep hum under control and avoid nasty little 100Hz sidebands at full power. I'd very much like to see a Quad II full power distortion spectrum - I suspect it wouldn't be nice at all and together with the anaemic output transformer would explain the soggy bass with electromagnetic loudspeakers."
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