Hello Thorsten,
I am having a Grayhill 12 position rotary switch with me and would like to try out the concept. I am planning to custom wind a transformer for the application. Can you let me know the transformer parameters required (Primary count, Secondary count, Impedance values etc) ?
Best regards,
Bins.
I am having a Grayhill 12 position rotary switch with me and would like to try out the concept. I am planning to custom wind a transformer for the application. Can you let me know the transformer parameters required (Primary count, Secondary count, Impedance values etc) ?
Best regards,
Bins.
Hi,
Good luck. You will need it. If you know how to wind a high performance line transformer you may stand a chance.
Sorry, but I do not provide such information. Any technical information that is in the public domain is on the linked page.
Ciao T
Good luck. You will need it. If you know how to wind a high performance line transformer you may stand a chance.
Sorry, but I do not provide such information. Any technical information that is in the public domain is on the linked page.
Ciao T
Hi,
By reading the technical details of TX-102, I was able to extract the following point:
>> Both the primary and secondary is having the same DC winding resistance. The secondary is having 'n' number of taps each providing a particular attenuation value. [The full primary has around 200 Ohm DC Winding resistance. The same applies for the secondary winding. The primary inductive reactance at 20 Hz is in excess of 50 kOhm (400 H Primary Inductance) and thus provides an input impedance of more than 50 kOhm across the audio band if the secondary loading is infinite]
Few questions are:
1. Are they having the same turns count ?
2. How to compute the no.of turns required for each dB tap ?
Best regards,
Bins.
By reading the technical details of TX-102, I was able to extract the following point:
>> Both the primary and secondary is having the same DC winding resistance. The secondary is having 'n' number of taps each providing a particular attenuation value. [The full primary has around 200 Ohm DC Winding resistance. The same applies for the secondary winding. The primary inductive reactance at 20 Hz is in excess of 50 kOhm (400 H Primary Inductance) and thus provides an input impedance of more than 50 kOhm across the audio band if the secondary loading is infinite]
Few questions are:
1. Are they having the same turns count ?
2. How to compute the no.of turns required for each dB tap ?
Best regards,
Bins.
Last edited:
Hi,
Honestly, if you understood at least the minimum details about audio transformers, you would not need to ask these kind of questions.
I suggest you abandon attempts to work on your own volume control transformer until you studied the subject thoroughly.
I would also add that just knowing the numbers of turns is insufficient.
In order to get acceptable audio performance you need to use suitable winding structures (they are not wound like mains transformers) and suitable core materials (any grade of steel is not an option). And no, I am not willing or interested to place such information into the public domain.
If you do not wish to buy a commercial offering from companies who have spend a lot of time on development, that is your call. But do not expect to produce anything serviceable yourself any time soon.
Ciao T
Honestly, if you understood at least the minimum details about audio transformers, you would not need to ask these kind of questions.
I suggest you abandon attempts to work on your own volume control transformer until you studied the subject thoroughly.
I would also add that just knowing the numbers of turns is insufficient.
In order to get acceptable audio performance you need to use suitable winding structures (they are not wound like mains transformers) and suitable core materials (any grade of steel is not an option). And no, I am not willing or interested to place such information into the public domain.
If you do not wish to buy a commercial offering from companies who have spend a lot of time on development, that is your call. But do not expect to produce anything serviceable yourself any time soon.
Ciao T
Hello,
Using the TVC was not my original idea. My aim was to use a 1:1 audio transformer with a 100K logarithmic pot (Something like the one shown on: The Ingot by Peerless ~ A Passion for Performance). Also, a fixed resistor is added across the secondary to create an idealized constant rather than varying load for the transformer and insure linear impedance matching regardless of attenuation.
Few questions:
1. What all factors should to be observed in selecting the transformer ? Will the NTE1 from Neutrik enough (Neutrik - Audio - Transformers - NTE1) ?
Best regards,
Bins.
Using the TVC was not my original idea. My aim was to use a 1:1 audio transformer with a 100K logarithmic pot (Something like the one shown on: The Ingot by Peerless ~ A Passion for Performance). Also, a fixed resistor is added across the secondary to create an idealized constant rather than varying load for the transformer and insure linear impedance matching regardless of attenuation.
Few questions:
1. What all factors should to be observed in selecting the transformer ? Will the NTE1 from Neutrik enough (Neutrik - Audio - Transformers - NTE1) ?
Best regards,
Bins.
Hi,
Yes, Silk & S&B TVC's appears to be based on the specification set. I hope that Kitipol at Silk did not just purchase a set of S&B's and copied them fully...
The issue with Load is addressed in the S&B Information. Basically, if the load is very low you will loose high frequency extension at the very high level settings and the load on the source will become severe.
As a rule the recommendation is IHF Load (10K//1nF) or higher impedances. If using the 0.5:1 stepup (6dB passive gain) this translates into a load on the source of 2.5K//4nF which is quite severe loading for most gear, so 10K//1nF is not really suggested for use with gain.
But again, this all depends on the system context. Martin Colloms tested the S&B on the AP2 using 600 Ohm loading and found nothing too undue in the results (unlike with active line stages).
Hence the lack of a straight answer. Simply because there ain't one.
Ciao T
Yes, Silk & S&B TVC's appears to be based on the specification set. I hope that Kitipol at Silk did not just purchase a set of S&B's and copied them fully...
The issue with Load is addressed in the S&B Information. Basically, if the load is very low you will loose high frequency extension at the very high level settings and the load on the source will become severe.
As a rule the recommendation is IHF Load (10K//1nF) or higher impedances. If using the 0.5:1 stepup (6dB passive gain) this translates into a load on the source of 2.5K//4nF which is quite severe loading for most gear, so 10K//1nF is not really suggested for use with gain.
But again, this all depends on the system context. Martin Colloms tested the S&B on the AP2 using 600 Ohm loading and found nothing too undue in the results (unlike with active line stages).
Hence the lack of a straight answer. Simply because there ain't one.
Ciao T
Hey T,
Suppose you know that Brian at diyHiFisupply first sold/represented S&B and then switched to Silk
.
Actuallly in the vague answer from Silk I got through Brian they indicated to go for the lightest load possible ie only the input Z of the next stage.
Actually as the secondary changes at every tap the load should maybe also change?
My own experience goes for lot of audio transformers: go for light load and don´t mind the squarewave overshoots. Up to a certain extent of course...
Suppose you know that Brian at diyHiFisupply first sold/represented S&B and then switched to Silk
. Actuallly in the vague answer from Silk I got through Brian they indicated to go for the lightest load possible ie only the input Z of the next stage.
Actually as the secondary changes at every tap the load should maybe also change?
My own experience goes for lot of audio transformers: go for light load and don´t mind the squarewave overshoots. Up to a certain extent of course...
Hi,
I do not wish to be seem directly criticising another industry member and manufacturer, so I will refrain from commenting, other than noting that what this is merely the combination of a very traditional "passive pre-amplifier" with a 1:1 Line transformer.
The Line transformer has no function other than to isolate input and output. This can have benefits in systems where there is poor design with sources or amplifiers in terms of ground/earth arrangements. This subject was considerably enlarged in another thread you have already found.
http://www.diyaudio.com/forums/tubes-valves/51391-poor-mans-transformer-volume-control.html
Frequency response, primary and secondary impedance and level handling. I personally also would add sound quality to the requirements.
That depends on your exact system context and your definition of "good enough".
A nominal impedance of 200 ohm means it should be driven by no more than 200 Ohm, preferably by much less than that, to attain the specified performance.
No frequency response is given, so your guess is as good as mine as to what this would be.
A level of -3dBU means around 0.5V, at which point for a 50Hz signal the transformer is practically at overload. For a 20Hz signal the transformer will overload with around 0.2V.
So you need to decide if this means your definition of "good enough".
Ciao T
I do not wish to be seem directly criticising another industry member and manufacturer, so I will refrain from commenting, other than noting that what this is merely the combination of a very traditional "passive pre-amplifier" with a 1:1 Line transformer.
The Line transformer has no function other than to isolate input and output. This can have benefits in systems where there is poor design with sources or amplifiers in terms of ground/earth arrangements. This subject was considerably enlarged in another thread you have already found.
http://www.diyaudio.com/forums/tubes-valves/51391-poor-mans-transformer-volume-control.html
Frequency response, primary and secondary impedance and level handling. I personally also would add sound quality to the requirements.
That depends on your exact system context and your definition of "good enough".
A nominal impedance of 200 ohm means it should be driven by no more than 200 Ohm, preferably by much less than that, to attain the specified performance.
No frequency response is given, so your guess is as good as mine as to what this would be.
A level of -3dBU means around 0.5V, at which point for a 50Hz signal the transformer is practically at overload. For a 20Hz signal the transformer will overload with around 0.2V.
So you need to decide if this means your definition of "good enough".
Ciao T
Hi,
Yes. I am still friends friends with both Brian and Jonathan.
I generally would agree with this. If a TVC is correcty designed, it wil not require any specific loading.
Yes, this is one way of viewing it. Personally I did not find this necessary or beneficial.
Agreed again. If the overshoot goes too far you can snub it using an RC circuit across the whole secondary.
Ciao T
Suppose you know that Brian at diyHiFisupply first sold/represented S&B and then switched to Silk
Yes. I am still friends friends with both Brian and Jonathan.
I generally would agree with this. If a TVC is correcty designed, it wil not require any specific loading.
Yes, this is one way of viewing it. Personally I did not find this necessary or beneficial.
Agreed again. If the overshoot goes too far you can snub it using an RC circuit across the whole secondary.
Ciao T
Hello,
1. I think the passive preamp will require a bit more input impedance than the 200 Ohms. Can we use this transformer for the purpose : Neutrik - Audio - Transformers - NTL1 ?
2. What will be the result if we use a 1:2 transformer instead of the 1:1 model ?
Best regards,
Bins.
1. I think the passive preamp will require a bit more input impedance than the 200 Ohms. Can we use this transformer for the purpose : Neutrik - Audio - Transformers - NTL1 ?
2. What will be the result if we use a 1:2 transformer instead of the 1:1 model ?
Best regards,
Bins.
Hi,
You can use what you like.
To be direct, a line input transformer that is suitable will cost nearly as much as a real TVC. In essence a TVC as I specify it, is nothing much different than a 1:1 line transformer at 10K nominal impedance, but with tapped secondary and a suitably changed winding structure. This was done as at the time really high performance 10K 1:1 line transformers where made by several manufacturers, so chances where good to convince at least one to make TVC modification.
FWIW, the "Ingot" uses a Magnequest transformer, quite likely the B7 10k:10k
Magnequest Products - MQ Iron Listing/Pricing
Use that with P&G 10K pot:
http://www.diyaudio.com/forums/swap-meet/6884-fs-trade-penny-giles.html
Ciao T
You can use what you like.
To be direct, a line input transformer that is suitable will cost nearly as much as a real TVC. In essence a TVC as I specify it, is nothing much different than a 1:1 line transformer at 10K nominal impedance, but with tapped secondary and a suitably changed winding structure. This was done as at the time really high performance 10K 1:1 line transformers where made by several manufacturers, so chances where good to convince at least one to make TVC modification.
FWIW, the "Ingot" uses a Magnequest transformer, quite likely the B7 10k:10k
Magnequest Products - MQ Iron Listing/Pricing
Use that with P&G 10K pot:
http://www.diyaudio.com/forums/swap-meet/6884-fs-trade-penny-giles.html
Ciao T
Hi,
The Neutrik transformers are readily available with me and that is why I had asked. I think the Neutrik NTL1 is having almost similar specifications as that of the Magnequest B7-10K:10K version.
1. What will happen if I omit the 1K fixed resistor that is added across the secondary to create an idealized constant ? Will it significantly degrade the performance ?
Best regards,
Bins.
The Neutrik transformers are readily available with me and that is why I had asked. I think the Neutrik NTL1 is having almost similar specifications as that of the Magnequest B7-10K:10K version.
1. What will happen if I omit the 1K fixed resistor that is added across the secondary to create an idealized constant ? Will it significantly degrade the performance ?
Best regards,
Bins.
Attachments
Hi,
First, non of the Neutrik transformers are very good. Second, I do not think they have the same specifications as the B7. Only in the very limited specifications given are there some parallels.
What 1K resistor across the secondary? Neither does the drawing attached to your post show such nor was any such ever in any published "Ingot" drawings.
Ciao T
First, non of the Neutrik transformers are very good. Second, I do not think they have the same specifications as the B7. Only in the very limited specifications given are there some parallels.
What 1K resistor across the secondary? Neither does the drawing attached to your post show such nor was any such ever in any published "Ingot" drawings.
Ciao T
Hi,
The 1K resistor is shown at the output end after the pot. What is the best value for the log pot (Is there any specific reason for using the 10K version) ?
Best regards,
Bins.
The 1K resistor is shown at the output end after the pot. What is the best value for the log pot (Is there any specific reason for using the 10K version) ?
Best regards,
Bins.
Hi,
Yes. And next to it it says "to bass amp".
So why do you claim that this resistor: " is added across the secondary to create an idealized constant ? " when it clearly is not added across the secondary first of all, never mind the rest?
The value that matches the transformer of course.
The secondary winding of the transformer in your drawing is 10K impedance.
Plus, there are the usual considerations for "passive pre-amplifiers", which pretty much dictate a 1K pot to be desirable (but few sources sound good driving such a load) and a 10K as the upper end of the value range, to ensure reasonably wide system compatibility.
Please forgive, but many of your questions seem incredibly naive. Would you mind finding yourself a good book on audio electronics and actually reading it? It would inform you much better than this "q & a" game you are playing here.
Second, given your current level of knowledge I think what you are trying to do is a fools errand. If you are absolutely bent on doing it anyway, good luck.
If so, take my suggestion and use the original transformer of the device you want to copy, or look for Sy's heretical linestage and use the Jensen Transformer he used. I suspect either will be largely redundant though, depending on the rest of your system. The Neutrik Transformers may be best described as "functional, of sorts".
Second, have a look at Nelson Pass's B1 Preamplifier, this kind of buffer is a very good idea to use after a higher impedance potentiometer to overcome some of the limitations of traditional "passive pre-amplifiers".
FWIW, Steve McCormack's most recent passive preamplifier uses such a buffer potentiometers and transformers to make a device that has certainly be reviewed very well.
Ciao T
Yes. And next to it it says "to bass amp".
So why do you claim that this resistor: " is added across the secondary to create an idealized constant ? " when it clearly is not added across the secondary first of all, never mind the rest?
The value that matches the transformer of course.
The secondary winding of the transformer in your drawing is 10K impedance.
Plus, there are the usual considerations for "passive pre-amplifiers", which pretty much dictate a 1K pot to be desirable (but few sources sound good driving such a load) and a 10K as the upper end of the value range, to ensure reasonably wide system compatibility.
Please forgive, but many of your questions seem incredibly naive. Would you mind finding yourself a good book on audio electronics and actually reading it? It would inform you much better than this "q & a" game you are playing here.
Second, given your current level of knowledge I think what you are trying to do is a fools errand. If you are absolutely bent on doing it anyway, good luck.
If so, take my suggestion and use the original transformer of the device you want to copy, or look for Sy's heretical linestage and use the Jensen Transformer he used. I suspect either will be largely redundant though, depending on the rest of your system. The Neutrik Transformers may be best described as "functional, of sorts".
Second, have a look at Nelson Pass's B1 Preamplifier, this kind of buffer is a very good idea to use after a higher impedance potentiometer to overcome some of the limitations of traditional "passive pre-amplifiers".
FWIW, Steve McCormack's most recent passive preamplifier uses such a buffer potentiometers and transformers to make a device that has certainly be reviewed very well.
Ciao T
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.