I get that. What I do not fully understand is "Why not a 1:2 transformer instead of an autoformer?" Are there inherent benefits in going the autoformer route?
I think it's because you can use a 150:150 quadfilar transformer, and wire it as you desire. Isolation or gain.
Well, this was not evident by your question.
There are lots of 1:1 transformers out there and not too many 1:2 autoformers unless you get them custom wound.
Do you know of many 1:2 autoformers that are available?
In addition there is the simplicity of the autoformer which many have found to sound better than an equivalent transformer.
I am going to use a 1:2 transformer since I want to incorporate polarity reversal. But that would be the only reason to not use the autoformer in ZM's scheme.
There are lots of 1:1 transformers out there and not too many 1:2 autoformers unless you get them custom wound.
Do you know of many 1:2 autoformers that are available?
In addition there is the simplicity of the autoformer which many have found to sound better than an equivalent transformer.
I am going to use a 1:2 transformer since I want to incorporate polarity reversal. But that would be the only reason to not use the autoformer in ZM's scheme.
question is , as I understood it , why autoformer and not transformer ?
answer is simple - because I'm living in conviction that autoformer is much less critical to make/buy/have ....... than xformer , asking from both same level of transfer purity/quality
xformer is irreplaceable when one needs galvanic isolation ; in this case we don't need that , so why not going for less critical solution , for same result ........
now , some news (finally)
after waiting my first-choice Winder guy - 2 months ( and some) for nothing , I sent my precious Metglas cores to different Winder guy (this time having some luck in fact that actual guy is friend of mine) ..... today he sent me viber pics of measurements of first specimen of SE AVC , conducted with some modernvodoogizmo digital Tektronix gear
results are veeery promising , these days I'll conduct some listening tests (with not just my pair of venerable ears, but also with few younger ones) and , in meantime , we'll work on logistic for Bal AVC
answer is simple - because I'm living in conviction that autoformer is much less critical to make/buy/have ....... than xformer , asking from both same level of transfer purity/quality
xformer is irreplaceable when one needs galvanic isolation ; in this case we don't need that , so why not going for less critical solution , for same result ........
now , some news (finally)
after waiting my first-choice Winder guy - 2 months ( and some) for nothing , I sent my precious Metglas cores to different Winder guy (this time having some luck in fact that actual guy is friend of mine) ..... today he sent me viber pics of measurements of first specimen of SE AVC , conducted with some modernvodoogizmo digital Tektronix gear
results are veeery promising , these days I'll conduct some listening tests (with not just my pair of venerable ears, but also with few younger ones) and , in meantime , we'll work on logistic for Bal AVC
Thanks ZM. Measurements look good 🙂
Another qn on iron pre - can I use the Tamura TK-10 in place of the Jensen JT-123?
Thanks!
Sent from my iPad using Tapatalk
Another qn on iron pre - can I use the Tamura TK-10 in place of the Jensen JT-123?
Thanks!
Sent from my iPad using Tapatalk
Thanks again. Jensens are hard to get here. Easier for me to get used items on eBay
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Sent from my iPhone using Tapatalk
tired as Mad Hatter after two shifts ;
it's certainly more complicated and tiresome puttin' zero series specimens of SE AVC in test bed** , than it will be placing them on final pcb cradle , as intended
anyway , all efforts are granted , it measures and it sings spooky , even in quick line-up , with oldie Sony CD as source
tomorrow it goes to second pair of ears , less biased , and to direct comparison with Intact Audio (two-switch iteration) AVC - which is , incidentally,equipped with exactly same buffer combo.
good day it was ... and still is 🙂
** cassette deck case already known from start of the thread
it's certainly more complicated and tiresome puttin' zero series specimens of SE AVC in test bed** , than it will be placing them on final pcb cradle , as intended
anyway , all efforts are granted , it measures and it sings spooky , even in quick line-up , with oldie Sony CD as source
tomorrow it goes to second pair of ears , less biased , and to direct comparison with Intact Audio (two-switch iteration) AVC - which is , incidentally,equipped with exactly same buffer combo.
good day it was ... and still is 🙂
** cassette deck case already known from start of the thread
Attachments
just to inform ya that SE AVC passed all listening tests ...... both critical and non-critical
now working on decent bobbins (did I tell that original ones are looking as one size bigger ? ....... so that's mentioned logistic for Bal AVC , and will be implemented for both SE and Bal iterations
also thinking about making fixture for vacuum varnishing them after assembly
why not .........
wow, I love you AVC!
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Maby we need metal box to protec your circuit from inductance and prevent AVCs from influencing each other.
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Maby we need metal box to protec your circuit from inductance and prevent AVCs from influencing each other.
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no need for that
all usual countermeasures are enough:
-regular size case for preamp (W438) , so mains xformer mount away of AVCs
-placement in system - put preamp normally away from big mains xformers (amplifier usually)
if you take a look at prototype cassette deck case , mains xformer is on one side , while AVCs are on the other ....... no hum, no buzz , even with case not connected to safety GND ( choice reserved only for Old farts , as I am ...... and even for them - just when prototype is in question)
with proper toroid (as we usually all use , not big chunk EI as I used in prototype) , danger of buzz is even smaller and requirements for placement are less critical
edit: and for pot cases , to be really effective , they really need to be made of thick steel material ; regarding mutual influence - naah ...... you can even find MC xformers in one common case for both channels ; stray field is negligent in this level of voltages
all usual countermeasures are enough:
-regular size case for preamp (W438) , so mains xformer mount away of AVCs
-placement in system - put preamp normally away from big mains xformers (amplifier usually)
if you take a look at prototype cassette deck case , mains xformer is on one side , while AVCs are on the other ....... no hum, no buzz , even with case not connected to safety GND ( choice reserved only for Old farts , as I am ...... and even for them - just when prototype is in question)
with proper toroid (as we usually all use , not big chunk EI as I used in prototype) , danger of buzz is even smaller and requirements for placement are less critical
edit: and for pot cases , to be really effective , they really need to be made of thick steel material ; regarding mutual influence - naah ...... you can even find MC xformers in one common case for both channels ; stray field is negligent in this level of voltages
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aha
again , I've bee workin' on the vailvoad ....
Stereo SE or Mono Bal - AVC pcb
main work done , left just some cosmetic clean up
again , I've bee workin' on the vailvoad ....
Stereo SE or Mono Bal - AVC pcb
main work done , left just some cosmetic clean up
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to keep it plain at this time of day : ), ONE of this for SE stereo, and it´s milimeters?
(a last zip of wine and to bed)
tnx,
stefan
(a last zip of wine and to bed)
tnx,
stefan
yup
one of these for stereo SE (pcb being in sandwich between two Irons)
and two of these for stereo Bal (one Iron on top of pcb)
yup milimeters
or you prefer that much inches ?
one of these for stereo SE (pcb being in sandwich between two Irons)
and two of these for stereo Bal (one Iron on top of pcb)
yup milimeters
or you prefer that much inches ?
yup
one of these for stereo SE (pcb being in sandwich between two Irons)
and two of these for stereo Bal (one Iron on top of pcb)
yup milimeters
or you prefer that much inches ?
😀yes, having been really tired ystrdy.
As I might play around with a case before getting pcb´s, could you comment about the hight of the AVC sandwich? It is fixed than in position via the PCB mounting screws, right?
Maybe i still start with a ordinary pot and the Jensens, but case wants to be big enough for AVC upgrade.
tnx
thinking of 2HE cases and variations of real space in them ........ :
-80mm of height in case should be real tight
-85mm of height in case should be plenty
that speaking of SE iteration ; for Bal count on half of that
or just use 3HE case , so you can ignore that issue
-80mm of height in case should be real tight
-85mm of height in case should be plenty
that speaking of SE iteration ; for Bal count on half of that
or just use 3HE case , so you can ignore that issue