According to Dave Slagle's web site the impedance shown to the source is:
"It is the reflected load in parallel with the inductive reactance of the autoformer. When set for no attenuation, the reflected load is simply whatever follows the volume control in the signal chain. However, that load is cut in half (resistance is doubled) for every 3dB of attenuation. At -20dB the reflected load value is increased by a factor of 100. At -40dB it is increased by a factor of 10,000 which is 10,000 times the resistance!
The simplified approach is to determine the desired load taking into consideration the lowest frequency of interest and doing a few simple calculations. For example: If your source is a CD player with a 50 ohm Z-out and you want to adhere to the 1:10 ratio of source to load many suggest all you need ot do is pick a suitable low frequency (often 20hz) and plug the numbers into the Z=2piFL formula to get, 500=2*pi*20*L. Solving for L gives you a required 4hy inductance to provide a 500 ohm load to a 50 ohm source."
"It is the reflected load in parallel with the inductive reactance of the autoformer. When set for no attenuation, the reflected load is simply whatever follows the volume control in the signal chain. However, that load is cut in half (resistance is doubled) for every 3dB of attenuation. At -20dB the reflected load value is increased by a factor of 100. At -40dB it is increased by a factor of 10,000 which is 10,000 times the resistance!
The simplified approach is to determine the desired load taking into consideration the lowest frequency of interest and doing a few simple calculations. For example: If your source is a CD player with a 50 ohm Z-out and you want to adhere to the 1:10 ratio of source to load many suggest all you need ot do is pick a suitable low frequency (often 20hz) and plug the numbers into the Z=2piFL formula to get, 500=2*pi*20*L. Solving for L gives you a required 4hy inductance to provide a 500 ohm load to a 50 ohm source."
Agree Jwag for me transfomers are very good over resistive but they cant handle any DC hence what comes before it has to have zero dc
which mostly means a blocking cap. This in itself also affects SQ lots & also dynamics would be affected with autoformers, my own dac I run
a 1:1 600 ohm line out trafo which can handle 100ma of dc & yes Im guilty as Im using Vicol Audio's relay resister VR.
Oh I may be flame for saying this but ESR of caps are not the be it all in obtaining gd sound, on certain parts of digital circuit perhaps.
We can all be arguing over this topic with no end, for those whose got itchy compulsive curious fingers like mine will understand what
Im trying to say.
Cheers
which mostly means a blocking cap. This in itself also affects SQ lots & also dynamics would be affected with autoformers, my own dac I run
a 1:1 600 ohm line out trafo which can handle 100ma of dc & yes Im guilty as Im using Vicol Audio's relay resister VR.
Oh I may be flame for saying this but ESR of caps are not the be it all in obtaining gd sound, on certain parts of digital circuit perhaps.
We can all be arguing over this topic with no end, for those whose got itchy compulsive curious fingers like mine will understand what
Im trying to say.
Cheers
Have you ever had a commercial component output DC? Adding a cap before the volume control seems a bit too cautious for a problem you are very unlikely to encounter. But perhaps if I had equipment damaged by such a thing I would feel differently. Is this really a problem that is likely to occur? I would like to hear about it if it is. I never gave it any thought.
I have the attached model. They will do custom ones as well if you need a certain impedance.
There is a lot of information here https://intactaudio.com/atten_FAQ.html
If you have the money to spend I would recommend getting the models where you provide the switch or get one of the nicer models they have. The switch on these is kinda cheap. I had one break but he sent me a new switch and I fixed it myself. Still a nice Elna switch would be better.
2880 American Euros for a usable stereo 47 position version is more than my complete setup costs….
Never got around just 23 steps. A relay controlled 64 step controller is affordable and also better than potentiometers.
Never got around just 23 steps. A relay controlled 64 step controller is affordable and also better than potentiometers.
For silver wound they cost that much. Copper is $1080
I went with the 23 position copper version for $475
I went with the 23 position copper version for $475
I don't get the point of these. Can't you just get a proper low Z line stage (like an OPA1637 configured as buffer) to drive any attentuator and be done with it?
Your dac output will surely have a low pass circuit which consist of a cap & resistor to ground unless it ist either servo control or has a line opt trafo.
Goes for preamps etc too.
These replace resistive volume controls with much better clarity and resolution. On my system at least it was a striking improvement.
Maybe it was not only resistive versus inductive but simple high quality against standard quality. Relay based also sounds better than many standard quality audio potentiometers.
jwags81818,Regarding the DACT volume control,I`m not surprised the autoformer was better because the DACT was made to mimic a normal pot by having 24 resistors allways in the signal path unlike a switched ladder type which has only two resistors at any one time.
I do agree.
KZ trebles /upper midrange are a no go or needs to be tamed by // cap or better by mixing it with another model on the other branch of an opamp. I call that asymétric decoupling.
BG N, yup but sometimes à BG std can be better in PS decoupling with the trick above.BG NX...I dislike often.
Silmic 2 : I was an opposant here. Will not be missed. Too much colored.
Nichicon KA, UFG....terribles.
KG will be missed.
I love too mix Panasonic, while often the FM can have a sort of fatiguing to the ears odd harmonics peakness behavior but sole combo value/voltage.
Some Jamicon are usefull but hard to get.
Philips's... like the Silmic 2 in the sense of desiquilibrium are à no go.
I tried à lot, but the Mundorf but the one by their german maker.
SIC Safco...among the best for high power amp. Not avialable, béats Sikorel hands in the pocket.
Etc.
We exchanged à lot with Sumotan years ago in pm and came to the same conclusions: despite à respectable behavior caps models can not really be scallled. Each circuitry for tonal balancing needs à complex and time consument process, expérience shorten it.
The said Silmic and Silmic 2 can save your life in série as a DC blocker sometimes to tame some nastyness of old cd player or input stages.
But à good DC coupling if elswhere the caps fir decoupling are well chosen is un beat able.
KZ trebles /upper midrange are a no go or needs to be tamed by // cap or better by mixing it with another model on the other branch of an opamp. I call that asymétric decoupling.
BG N, yup but sometimes à BG std can be better in PS decoupling with the trick above.BG NX...I dislike often.
Silmic 2 : I was an opposant here. Will not be missed. Too much colored.
Nichicon KA, UFG....terribles.
KG will be missed.
I love too mix Panasonic, while often the FM can have a sort of fatiguing to the ears odd harmonics peakness behavior but sole combo value/voltage.
Some Jamicon are usefull but hard to get.
Philips's... like the Silmic 2 in the sense of desiquilibrium are à no go.
I tried à lot, but the Mundorf but the one by their german maker.
SIC Safco...among the best for high power amp. Not avialable, béats Sikorel hands in the pocket.
Etc.
We exchanged à lot with Sumotan years ago in pm and came to the same conclusions: despite à respectable behavior caps models can not really be scallled. Each circuitry for tonal balancing needs à complex and time consument process, expérience shorten it.
The said Silmic and Silmic 2 can save your life in série as a DC blocker sometimes to tame some nastyness of old cd player or input stages.
But à good DC coupling if elswhere the caps fir decoupling are well chosen is un beat able.
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Nice to see you here Iggy, yes BG std sounds great with Elna cerafine combi, its looses out to BGN on drive & punch.
I've no doubt that Intact stuff is good but their prices now to me is out of whack sorry
Hi all,
A quick question: Any of you ever tried something like this as an alternative to smaller value electrolytic (or similar) capacitors:
https://www.mouser.dk/ProductDetail/KEMET/C4AQLBW5500M3JK?qs=81r%2BiQLm7BQ0haztxIs6Tw==
In spite of the wide pin distances it has a reasonably low inductance (10 nH) and a very low ESR (2.8 mohm).
Might one of you have tried something like this and maybe have some experiences to share?
Cheers,
Jesper
A quick question: Any of you ever tried something like this as an alternative to smaller value electrolytic (or similar) capacitors:
https://www.mouser.dk/ProductDetail/KEMET/C4AQLBW5500M3JK?qs=81r%2BiQLm7BQ0haztxIs6Tw==
In spite of the wide pin distances it has a reasonably low inductance (10 nH) and a very low ESR (2.8 mohm).
Might one of you have tried something like this and maybe have some experiences to share?
Cheers,
Jesper
Well Im curious about DC Link caps too shall try them when I build my Dht linestage on ps side
@sumotan: Thanks for your feedback 😉 ... Looking forward to hearing about your impressions if you'd like to share them ...
BTW I (or an internet calculator, rather) just did a calculation of the resonance frequency of the capacitor I linked to above and it is about 225 kHz - could be OK - but with a Q of ~5. So it likely will not silence itself instantly when the frequencies are in this region.
Cheers, Jesper
BTW I (or an internet calculator, rather) just did a calculation of the resonance frequency of the capacitor I linked to above and it is about 225 kHz - could be OK - but with a Q of ~5. So it likely will not silence itself instantly when the frequencies are in this region.
Cheers, Jesper