Winston OBoogie
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M610 Tube Microphone & Instrument Preamplifier
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Winston OBoogie
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Winston OBoogie
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SonsOfThunder
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Just curious to know if the CMO-30/600 would be right for an O/P trafo?
Thanks!
Thanks!
rafafredd
Well-known member
[quote author="Winston O'Boogie"]
Alternatively, you could try impedance coupling if you want to keep DC out of the traffo but don't want the voltage drop of a resistor.
[/quote]
Can´t figure out what you mean by "impedance coupling" here. Is it a plate choke?
Alternatively, you could try impedance coupling if you want to keep DC out of the traffo but don't want the voltage drop of a resistor.
[/quote]
Can´t figure out what you mean by "impedance coupling" here. Is it a plate choke?
He probaly does mean parafeed. The standars V72 type choke fed output stage.
My guess at least.
My guess at least.
NewYorkDave
Well-known member
Yeah, "impedance coupling" means a plate choke and a coupling capacitor. You can find it in most old electronics texts.
rafafredd
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well, high inductance plate chokes are expensivier than most quality gapped transformers.
SonsOfThunder
Well-known member
[quote author="SonsOfThunder"]if the CMO-30/600 would be right[/quote] The website says this can be gapped as an option...?
Paging Dr. Boogie..Dr. Boogie...
Paging Dr. Boogie..Dr. Boogie...
Winston OBoogie
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NewYorkDave
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Don't feel bad, I call it "impedance coupling", too. I learned much of what I know from the ancient dusty texts.
"Parafeed" is a term that comes from the audiophile tweako crowd and I don't associate with that lot. :wink:
"Parafeed" is a term that comes from the audiophile tweako crowd and I don't associate with that lot. :wink:
rafafredd
Well-known member
[quote author="Winston O'Boogie"]Rafa - I wasn't suggesting it as a more economical solution but as something to try if you were inclined. One of these days I'll have some spare time on my hands and I'll give this a try myself.
John[/quote]
What are the sources for high inductance plate chokes? I know Lundahl has some and also Hammond, I think. But, if you have any other sources you can share, it would be nice to know...
John[/quote]
What are the sources for high inductance plate chokes? I know Lundahl has some and also Hammond, I think. But, if you have any other sources you can share, it would be nice to know...
Bartolucci for the cadilac of plate chokes, Sowter has some. Almost anybody will make you one, since they are pretty simple.
I have a bookmark on a cool articl on how to size the choke if i can just find the darn thing.
I have a bookmark on a cool articl on how to size the choke if i can just find the darn thing.
NewYorkDave
Well-known member
How about power supply filter chokes... or is the distributed capacitance too high?
Winston OBoogie
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The Tele stuff is three chambers.
I haven't checked capacitance. UTC also made some plate chokes, but pretty rare on evilbay.
from ollie's site:
"The three-chamber plate inductor is mainly responsible for the high dynamic range of the V72 and V76, also the one that gave us a big head ache. Instead of a plain old resistor, a high nickel content inductor is used for inter- and output stage. About 6000 feet of magnet wire that is roughly 1/4 of the size of a human hair, wound with approx. 30000 turns onto a three chamber bobbin, keeping stray capacitance as low as possible. We found a bobbin manufacture that still had some NOS stock, but after getting the first samples, 40 years on a back shelf in a wear house made them same as fragile than the ones you find in the historic V units. Just careful touching can result in cracks or breaking. New ones couldn't be made, because tooling was decommissioned in the later 1970s. After several tries to replace it with Ferrite inductors, etc. we made a new set of tools.
So what is so special of this design? Not very often used in audio circuits, the only other application that we could find out was audio equipment made for the US Navy in the 1940s. The inductor allows a very high amplification over a wide frequency range with hardly any random noise created by standard plate resistor. Effective AC plate resistance is nearly 1M Ohm with a fraction of DC resistance, aside higher dynamic range, better S/N noise, it also allows less intermodulation distortion that gives the V72 and V76 its classic wide open tonal response."
http://www.tab-funkenwerk.com/blueprints.html
cj's custom diy chokes-M6 for less bass distortion but lower inductance:
I haven't checked capacitance. UTC also made some plate chokes, but pretty rare on evilbay.
from ollie's site:
"The three-chamber plate inductor is mainly responsible for the high dynamic range of the V72 and V76, also the one that gave us a big head ache. Instead of a plain old resistor, a high nickel content inductor is used for inter- and output stage. About 6000 feet of magnet wire that is roughly 1/4 of the size of a human hair, wound with approx. 30000 turns onto a three chamber bobbin, keeping stray capacitance as low as possible. We found a bobbin manufacture that still had some NOS stock, but after getting the first samples, 40 years on a back shelf in a wear house made them same as fragile than the ones you find in the historic V units. Just careful touching can result in cracks or breaking. New ones couldn't be made, because tooling was decommissioned in the later 1970s. After several tries to replace it with Ferrite inductors, etc. we made a new set of tools.
So what is so special of this design? Not very often used in audio circuits, the only other application that we could find out was audio equipment made for the US Navy in the 1940s. The inductor allows a very high amplification over a wide frequency range with hardly any random noise created by standard plate resistor. Effective AC plate resistance is nearly 1M Ohm with a fraction of DC resistance, aside higher dynamic range, better S/N noise, it also allows less intermodulation distortion that gives the V72 and V76 its classic wide open tonal response."
http://www.tab-funkenwerk.com/blueprints.html
cj's custom diy chokes-M6 for less bass distortion but lower inductance:
Winston OBoogie
Well-known member
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Winston OBoogie
Well-known member
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