Hi
Just wanted to say hi and what a great forum - refreshing change from most of the bs on the web...
I know some of you from the JoeNet or sunny (pah) London.
Currently hording parts for a DD ESL amp (this has been going on for years) - my London pals will tell you I should seek out a shrink who deals in analysis paralysis, but I've built a couple of guitar amps and a VV52 SE for treble opt evaluation.
Looking forward to hanging out here,
Cheers
Chris
World's most prolific on-paper builder
Just wanted to say hi and what a great forum - refreshing change from most of the bs on the web...
I know some of you from the JoeNet or sunny (pah) London.
Currently hording parts for a DD ESL amp (this has been going on for years) - my London pals will tell you I should seek out a shrink who deals in analysis paralysis, but I've built a couple of guitar amps and a VV52 SE for treble opt evaluation.
Looking forward to hanging out here,
Cheers
Chris
World's most prolific on-paper builder
Re: Government Issue
Welcome and I do like the signature and your "moniker" is of course an excellent choice.
When the US military started, during the Second World War, to organise their valve purchases they came up with "JAN" = Joint Army-Navy; have we a JAN here I wonder?
At the same time the British were in terrible shape with each of the three services providing their own nomenclature for valves of the same type. By 1943 this mess had been addressed, and the CV system was born.
I'm sorry to have to report that "CV" stands for "Common Valve" - actually in the sense that the valves were common to the three services (and also the Post Office and other Government organisations).
I am sure that the valves you hold and intend to hold are most unlikely to be "common"!
Best
7N7
CV said:
Welcome and I do like the signature and your "moniker" is of course an excellent choice.
When the US military started, during the Second World War, to organise their valve purchases they came up with "JAN" = Joint Army-Navy; have we a JAN here I wonder?
At the same time the British were in terrible shape with each of the three services providing their own nomenclature for valves of the same type. By 1943 this mess had been addressed, and the CV system was born.
I'm sorry to have to report that "CV" stands for "Common Valve" - actually in the sense that the valves were common to the three services (and also the Post Office and other Government organisations).
I am sure that the valves you hold and intend to hold are most unlikely to be "common"!
Best
7N7
Hello Jan, all,
7N7 you cheeky sod
7N7's well aware that my amps are mired in the conceptual plane and is currently seeking a UN resolution to boot them out...
Intentions: ESL midrange panels to be driven either by
a) 4212 SE with phase-splitter output transformer
Now this depends on how a prototype works out; very tricky spec indeed... should be hearing soon
Would like to try a 4304CB out as a driver cos they look super cool
OR
b) Fully differential 2/3 stage amp with current sources everywhere, including anode loads (shunted with high value resistors). This would either be 6S45 - 813 (triode connection) or (26/27/76/perhaps LP2) - 10Y - 845. Direct drive, no iron.
OR
c) Variation of B with 20H air-core choke load on the output stage, B+ at 0v. Lot like Remco's amp at www.ultranalog.com.
Again, waiting to here about air-core feasibility.
Running the ESLs (2.5nF load) midrange only greatly eases the current and Ri constraints on the output valves.
For the treble amp (driving a array of planar tweets), I'm either going to go for VV52 SE - lethal proto already lashed up and sounding very nice (lovely etheral quality, esp. cymbals and upper treble) with a Sowter mumetal OPT, or 6C33 SRPP (tweeters can be configured to 100 ohms) which I hope to build in the next few weeks. Will be interesting to see which one wins.
As you might guess, I'm a big believer in designing the amps around the speakers, especially when transformers are involved. This is a real luxury for us DIYers that the commercial guys don't have and why we should be able to beat them every time...
Cheers
Chris
7N7 you cheeky sod
7N7's well aware that my amps are mired in the conceptual plane and is currently seeking a UN resolution to boot them out...
Intentions: ESL midrange panels to be driven either by
a) 4212 SE with phase-splitter output transformer
Now this depends on how a prototype works out; very tricky spec indeed... should be hearing soon
Would like to try a 4304CB out as a driver cos they look super cool
OR
b) Fully differential 2/3 stage amp with current sources everywhere, including anode loads (shunted with high value resistors). This would either be 6S45 - 813 (triode connection) or (26/27/76/perhaps LP2) - 10Y - 845. Direct drive, no iron.
OR
c) Variation of B with 20H air-core choke load on the output stage, B+ at 0v. Lot like Remco's amp at www.ultranalog.com.
Again, waiting to here about air-core feasibility.
Running the ESLs (2.5nF load) midrange only greatly eases the current and Ri constraints on the output valves.
For the treble amp (driving a array of planar tweets), I'm either going to go for VV52 SE - lethal proto already lashed up and sounding very nice (lovely etheral quality, esp. cymbals and upper treble) with a Sowter mumetal OPT, or 6C33 SRPP (tweeters can be configured to 100 ohms) which I hope to build in the next few weeks. Will be interesting to see which one wins.
As you might guess, I'm a big believer in designing the amps around the speakers, especially when transformers are involved. This is a real luxury for us DIYers that the commercial guys don't have and why we should be able to beat them every time...
Cheers
Chris
on me
7N7 said:
Now then, politics or audio: which one is the art of the possible??
Not sure there N7, but if my oft-proposed grand plans, over-expenditure, strategy U-turns and distinct lack of actual progress are anything to go by then I'm destined for a glittering career in the former.
Now, Slowmotion (that should really be my moniker), about the linestages/crossover...
I've been thinking carefully about this one - if I can, the crossover will be incorporated in the amps in a super minimalist fashion. Let me illustrate with one idea I had; final topology will depend on whether the mid amp is SE or differential:
hope this isn't too tricky to picture:
SE input goes to a passive 4th order LCLC low-pass filter at 150Hz. This will go to the subs and their dipole EQ
Now here's the tricky bit. Hook up a diff pair between the output of the filter and the input. This forms a subtractive crossover and derives a hi-pass signal for the main mid/treble array *and* simultaneously we don't have to worry about generating balanced drive for the midrange amp.
[Unintuitively, this subtractive high-pass has a first order rolloff yet manages to sum perfectly with the 4th order LP, anyways...]
Ok, so now we have 4th order LP to the woofs and 1st order to the midrange.
To rolloff the treble to the midranges, I was considering adding resistors in series with the ESL panels - using their natural capacitance as part of an RC. This has the added plus that the valves see a much easier load at HF which helps to minimise the risk of slewing. My only concern with this is that the dynamics may be hindered.
For the treble amp - if not my current SET then it will be 6C33 SRPP driven via 6C45. Fixed bias to the 6C45 via blocking cap ,direct coupled to the 6c33s, these are then cap coupled to the tweeter array. I'll use the 2 time constants implicit there to provide the primary 1st order roll-off at 3-6k and also a few octaves down, I'll have another rolloff to help reduce tweet excursion and power demands/Imod on the treble amp. This will result in a near-enough transient perfect match with the mid panels.
So without really adding an obvious crossover, I'll hopefully have created a transient perfect one with 4th order cut to the bass (don't want them sneaking into the mids too much), quasi second order to the treble array, 1st order to the main mid panels with the balance drive generation built in.
I'd hope to use teflon caps and some polyprop in oils I have for the critical caps. The resulting sums imply a low impedance to the preamp, but that's ok, cos I'll be using a transformer volume control and that needs to be driven like that anyway. And in step-down it will drive the **** out of everything.
So hopefully as simple as possible, but no simpler.
Drat, I've almost convinced myself to build this thing now...
Hi Chris, all
Had to read that one a couple of times to get it into my head,
it's slowly creeping in, will take me some time to digest it all , though.
Your soon-to-be system is in some ways similar to the way
I am moving with my own system.
I am using horns instead of ESLs , dipole bass at the moment, with part of the crossovers incorporated into the amps.
Am constantly changing my mind on how to build things,
though, so progress is very slow, but moving in direction of CL
crossovers and away from cathode followers. Maybe.
Currently thinking about how to best make a linestage /
crossover with 3 separate outputs per channel, without making things more complicated than neccesary, we'll se how that goes
Had to read that one a couple of times to get it into my head,
it's slowly creeping in, will take me some time to digest it all , though.
Your soon-to-be system is in some ways similar to the way
I am moving with my own system.
I am using horns instead of ESLs , dipole bass at the moment, with part of the crossovers incorporated into the amps.
Am constantly changing my mind on how to build things,
though, so progress is very slow, but moving in direction of CL
crossovers and away from cathode followers. Maybe.
Currently thinking about how to best make a linestage /
crossover with 3 separate outputs per channel, without making things more complicated than neccesary, we'll se how that goes
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