Fortunately we aren't handling any real power above 20 KHz, so one may be able to compensate the feedback network for the frequency rolloff from the proximity and skin effects.
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"tnx smoking amp for clearing up what you ment by elliptron, never thougth it had a special name if you use a chocke. I played with that idea too, only would have put the chocke on the outer legs of the same core, just 1 more silly idea..."
Yes, for a made to order OT, that would make the best sense. I've just been using the separate choke scheme for modifying some Edcors using some nice inductors I found surplus cheap.
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"tnx smoking amp for clearing up what you ment by elliptron, never thougth it had a special name if you use a chocke. I played with that idea too, only would have put the chocke on the outer legs of the same core, just 1 more silly idea..."
Yes, for a made to order OT, that would make the best sense. I've just been using the separate choke scheme for modifying some Edcors using some nice inductors I found surplus cheap.
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For the mac i would expect some advantage at the high end regarding BW and also distortion do to less capacitiv loading.
For the ciclotron transformer related losses would be certainly lower at mid and low end. Therefore, if fed from a zero impedance voltagedistortion would also be lower. The mainadvantage i see when using low impedances and autotransformer operation.
But as you said, needs thorough investigation to make sure how things really are.
tnx for your description, will go through it tomorrow, first glanc impression is what ive seen done in some transistorized rf-amps with ferritcored pp/singled ended low impedace transformers.
later 😉
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I see.
But as I was suggesting, perhaps this is more of an RF effect than a <100kHz effect? SMPS are in the >100kHz. and these days in the low mHz. range. RF.
Again, a number associated with this "loss" would be more meaningful. How many dB loss could one expect at 100kHz. from these effects? At 50kHz.? If it is something like 0.1dB, then it is pretty safe to ignore it for the most part. Otoh, if one were to wind a transformer that by using the normal design equations is expected to work out to 100kHz, but comes much lower, maybe it makes sense to include these losses in the consideration. But does this ever happen?
Gorgon, the "numbers" I was asking smoking-amp for were the bandwidth numbers for his claim of the Circlotron vs. McIntosh OT units. He answered that question.
Smoking-amp, Another question, can the Circlotron amp ever become unbalanced for DC through a given winding? If so, I would not want to use toroids, since they (in my experience) do not like DC offsets on their core. Wondering if this is a factor.
Got a link to or a post of that Elliptron design? I do worry about using an electrolytic though. Interesting circuit idea. Hmmmm...
_-_-bear
Here is an elliptron schematic:
http://www.diyaudio.com/forums/tubes-valves/19624-elliptron-schematic.html#post228796
The center tapped inductor would be wound on the same core if custom designed. Otherwise its an add on for an off the shelf OT. I'm using a series combo of a single layer center tapped toroid (HF isolation) and a dual bobbin C core (LF isolation) for the add on inductor. The total inductor needs to be able to handle the AC voltage between the screen taps at audio with low magnetizing current.
Yes, the DC can become unbalanced in the Elliptron or Circlotron, just like any P-P OT if the tube idle currents are not balanced. Just occurs in the same winding instead of the two different windings for a conventional design. So a DC servo would be likely equipment for a toroid version.
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A comment on the 1st variant transmission line autoformer above, you'll notice that a lot more copper is required than a normal OT due to the widening conductors toward the low Z end. This would be something like (N+1)N/4 times as much copper as a normal OT. Hence the advantage of using the symmetrical back to back version mentioned with N/2.
Since the next isolated variant uses even more copper, 2X more, there could be some strong incentive to try placing a floating small wire primary between each of the layers in the 1st variant to get isolation. I don't know how well that would couple bandwidthwise though, but maybe all-right. (can always just put a cap between the windings anyway)
http://www.diyaudio.com/forums/tubes-valves/19624-elliptron-schematic.html#post228796
The center tapped inductor would be wound on the same core if custom designed. Otherwise its an add on for an off the shelf OT. I'm using a series combo of a single layer center tapped toroid (HF isolation) and a dual bobbin C core (LF isolation) for the add on inductor. The total inductor needs to be able to handle the AC voltage between the screen taps at audio with low magnetizing current.
Yes, the DC can become unbalanced in the Elliptron or Circlotron, just like any P-P OT if the tube idle currents are not balanced. Just occurs in the same winding instead of the two different windings for a conventional design. So a DC servo would be likely equipment for a toroid version.
-------------------
A comment on the 1st variant transmission line autoformer above, you'll notice that a lot more copper is required than a normal OT due to the widening conductors toward the low Z end. This would be something like (N+1)N/4 times as much copper as a normal OT. Hence the advantage of using the symmetrical back to back version mentioned with N/2.
Since the next isolated variant uses even more copper, 2X more, there could be some strong incentive to try placing a floating small wire primary between each of the layers in the 1st variant to get isolation. I don't know how well that would couple bandwidthwise though, but maybe all-right. (can always just put a cap between the windings anyway)
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Some lady told me a long time ago that she had an old McIntosh tube amp that caught fire while it was playing, and kept playing!
Could be an interesting advertising statement. The Energizer, keeps on playing, even when on fire.
Then there's the stories of amps being sent back to be repaired, with bullet holes in them from upset wives....
"Is it good or just popular ?"
The McIntosh's were well constructed, well engineered, reliable, low distortion, and expensive. Some people loved them, and some didn't.
The McIntosh's were well constructed, well engineered, reliable, low distortion, and expensive. Some people loved them, and some didn't.
Right, man!
Especially the MI350's were reliable and powerful enough for powering the PA system at the Three Days of Piece and Music festival at Woodstock.
Best regards!
when?
then or now?
back in the day the McIntosh was the Rolls-Royce of amplifiers, or the Cadillac if ur in the USA.
Imo, with the possible exception of the Partridge designed OT the McIntosh amp offered the most performance. Very few amps were built with the Partridge OTs... the Quad amp design was good also, but many feel it was sort of an end run to get around the patents that McIntosh had.
If you go back to early texts, like Terman, you will find a large number of cathode coupled output designs. Many variations were explored. The most successful was the McIntosh design, by far.
If you couple the basic McIntosh output stage with modern parts and input circuitry you get a result that is just about as good as you can get with tubes and an output transformer. As smoking-amp suggests the Circlotron in his opinion rivals the McIntosh in terms of performance. So, that is for an amp built today, using modern design ideas and parts. Very very good measured performance.
Some folks prefer the sonics of a SE DHT triode and some prefer a solid state amp of vanishingly low distortion... so it is difficult to talk about these things without the subjective perception coming into play.
My
worth..._-_-bear
The model Mc240 has a pair of ECC83/12AX7's with 430 volts DC anode to cathode. You commonly see these with the original (Telefunken) valves. Yikes!
Thanks,
Chris
Thanks,
Chris
"and using primary side crossovers"
I don't understand this portion of the sentence, could somebody please explain it ?
Thanks.
"and using primary side crossovers"
I don't understand this portion of the sentence, could somebody please explain it ?
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Just referring to maintaining full symmetry and interleaving between the two halves of a P-P primary winding when wound onto a split bobbin setup.
For example, one primary side could be 1/2 wound near the bottom of one bobbin and the other 1/2 of it near the top of the other bobbin. The other primary side then would be wound near the top of the 1st bobbin and near the bottom of the second bobbin. This keeps symmetry to the secondary for each primary side (and equal leakage inductances for accurate balance), and helps to increase coupling between the primary sections for better control of class aB crossover leakage inductance transients. (particularly if the two bobbins are on opposite legs of a C-core) I think Dynaco or someone had a patent on this winding scheme.
To apply this technique to a Mac OT, one would split the two bifilar sections into halves (still bifilar) and distribute the four resulting bifilar winding groups between the bobbins in the same balanced symmetry way. This would provide better coupling and Lleak balance between the normally 2 separate bifilar parts used by Mac. The Mac bifilar scheme provides good coupling between the internal bifilar portions, but not necessarily between the two separate primary bifilar windups. So one tube may still have less leakage inductance in it's cathode winding than the other tube. This balanced split bobbin technique would improve on that by equalizing them. (by the way, the Crowhurst twin coupled scheme can also provide this balance function by arranging the cross hookup symmetry properly.)
I don't understand this portion of the sentence, could somebody please explain it ?
----------------
Just referring to maintaining full symmetry and interleaving between the two halves of a P-P primary winding when wound onto a split bobbin setup.
For example, one primary side could be 1/2 wound near the bottom of one bobbin and the other 1/2 of it near the top of the other bobbin. The other primary side then would be wound near the top of the 1st bobbin and near the bottom of the second bobbin. This keeps symmetry to the secondary for each primary side (and equal leakage inductances for accurate balance), and helps to increase coupling between the primary sections for better control of class aB crossover leakage inductance transients. (particularly if the two bobbins are on opposite legs of a C-core) I think Dynaco or someone had a patent on this winding scheme.
To apply this technique to a Mac OT, one would split the two bifilar sections into halves (still bifilar) and distribute the four resulting bifilar winding groups between the bobbins in the same balanced symmetry way. This would provide better coupling and Lleak balance between the normally 2 separate bifilar parts used by Mac. The Mac bifilar scheme provides good coupling between the internal bifilar portions, but not necessarily between the two separate primary bifilar windups. So one tube may still have less leakage inductance in it's cathode winding than the other tube. This balanced split bobbin technique would improve on that by equalizing them. (by the way, the Crowhurst twin coupled scheme can also provide this balance function by arranging the cross hookup symmetry properly.)
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...except the McIntosh iron was bifilar wound.
...and I am told, more or less scramble wound, not terribly perfect at all. That may have changed or be different on some models, but I was told this by someone who unpotted some for rewinding...
...and I am told, more or less scramble wound, not terribly perfect at all. That may have changed or be different on some models, but I was told this by someone who unpotted some for rewinding...
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