Hi Janos, thanks for this great overview. For the DIY audio enthusiast there is an other trick you can do with resisters that may be interesting. Two examples that are basically variations on the same theme. If you have a DAC with a current output, you can use a current transformer to replace the typical op-amp. The secondary side of the transformer is then terminated with a resister. This serves two purposes. It will show an impedance to the DAC on the primary side, and it converts the current source in to a voltage source on the secondary side. The lower the impedance in which the DAC current output feeds, the better it is for the DAC and the sound quality. So you can make use of this by connecting this up with a stepped attenuator. A similar strategy is valid for a cathode follower. If you have a tube as cathode follower in your pre-amp, then you might as well use it to control the volume. This will result as well in a lower output impedance at lower volumes, just make the cathode resister a stepped attenuator. One word of caution though. Use this only with low power amps. Because a malfunction in the stepped attenuator (or a potmeter for that matter, that will work as well as budget alternative) will result in maximum volume. So this is not recommended for high power amps. To clarify, the stepped attenuator or potmeter is configured as variable shunt, with the wiper tied to the high side.
Thank you Hugo, great tips! ; ) The shunt pot trick is a very good one, I used it with my volume control pots - great way to boost a cheap pot when there's no funds for an expensive high quality one.
Dear Janos, Thank you very much for your comprehensive video response! I am also going to watch back your earlier videos about this subject. Hopefully I can make a decision afterwards. :) Interesting that you will soon introduce a new speaker design with baltic berch, which I will follow! 2025 Q1 I will be moving to a apartment, hopefully I can get started on my horn design soon after that, I will keep you posted. Thanks again!
Good luck for your new home, and enjoy the speaker build! My new speaker will be a transmission line for the biggest (12in) Sonido full range Alnico. ; )
Hi Nick, good luck on your new adventures! May I ask if it was you that had a dac made by Peter van Willenswaard? How are you enjoying it? Have you ever had the chance to compare it with AN? Best regards, Thiago
@ Thanks! I had the chance to listen for about couple of weeks to a dac made by PvW which sounded very good! I evaluated with a AN Dac3.1x/II, which was slightly more refined, but the AN dac was way more expensive. The PvW was a little bit more dynamic but also slightly more raw. For the price it’s a no brainer. In east Europe there as another tube dac manufacturer but I can’t remember the name. Something like Abbys. I think Herb Reichert spoke about this brand to
@@nicktube3904 Hi Nick, Thiago, it is Abbas audio in the Ukraine. He is extremely good, doing all the crazy stuff that I do. Well, not crazy, but he has that kind of deep understanding of both electronics and music perception.
Tube amps are more full range , and have high frequency , time delay. Digital amps are more octave specific. 20% tolerance in components , yields different frequency characteristics as well. With a DAW, we can now measure , and select a proper digital amplifier for the application. Octave range , distortion bubbles etc. 😊
This is a very interesting and timely video...I'm in the process of designing a tube based pre-amp and power-amp (both monoblocks) to build next year and have been considering how best to deal with a volume control, my thought leading me to perhaps a separate attentuator box in between pre- and power-amp: but I listen at low volumes 95% of the time so most of the volume control won't be used (if that makes sense). I had thought of having no volume control at all, but some means of providing a fixed volume level perhaps via the grid resistor, but now your video has given me lots of things to think about. I too am hoping to build another pair of speakers next year (that was scheduled for this year, but health issues intervened), perhaps a folded Voigt Pipe, not sure yet.
Thanks for this informative and helpful info. A few years ago a forum comment led me to the TVC units by Promitheus Audio. Comments on that forum were highly favorable of these TVC units. My question; is it possible and practical to include remote control functionality in a Transformer Volume Control?
It would be a useful feature, but retrofitting and existing unit can be from very hard to possible with a new cabinet. The entry-level Prometheus has space in the chassis for that, but for the big boys there's no space inside for the motor for the remote. (Basically you need to install a motor for the volume selector switch, and the electronics to make the motor work and comminicate with the remote.) It also injects noise to the line AC, that was my main reason to stay away from that. I guess today with LEDs everywhere and SMPSs everywhere, it will not hurt that much an already horrible situation we all are dealing with.
@@realworldaudio I was unaware of the Promitheus as "entry-level" but taking that as a given, who are the "big boys" and why do they not simply expand their chassis to accommodate a remote control motor? As for injecting noise into the AC line, given the state of tech today, I'd bet that can be easily eliminated.
@@geoffreydebrito2653 Handling line AC is worse today than it ever was, by a very very very veeeery long shot. The edge that a TVC brings over resistive or other volume control is easily more than offset by a remote unit installed inside. Also, building AVC/TVC requires a very different skillset from implementing remotes, and I do not know of any AVC tVC maker worth their salt who also builds one with a remote. It's always comfort versus performance... those who can add a remote know little about AVC / TVC, so bother not with that. We can compromise a little at every step and feel not much degradation, but once you start compromising in it adds up and we fall very short. AVC / TVC is for those who want no compromises to the sound, hence the total lack of remote ability from these units.
@@geoffreydebrito2653 Prometheus has entry level and high end TVCs. There's a vast difference in price and size between them. The entry level is flat, small and affordable. The high end units are heavy and enormous. And quite expensive as well.
Hi i just searched abit on the grid chokes what forums do you search for comments on them i found this on diyaudio " Tekton is probably right. At one point plate and grid chokes were all the rage in tube amps. Until ONE well known tweeker in Diy circles posted he doesn't like them anymore because they form a resonance circuit and the resulting sound is reflection of that fact. After that pretty much everybody heard those resonances and plate/grid chokes ended up in the landfill" Also have you ever heard a plasma based tweeter?
I have not followed forums for the past 10 years... I quit because trolls taking over on forums, that's the reason I started this channel, to share in a civilized manner. ; ). To me that claim seems to be an over-exaggeration. A resonance with the grid choke would be in most cases very far out of the hearing range. Plus the resonance is also the function of the capacitance that it's reacting with, so I'd say if one has an issue with grid or plate choke related resonances, they have a fundamental issue that they have overlooked in the design and the issue is not the choke but the parasitic capacitance that creates the resonance. Kind of like saying driving driving a car is not safe because you fall out of the car. However, the car is driven with an open door, and the driver is unaware of the existence of door and use of the seat belt...Drive with a closed door, engage seat belt, and it's safe to drive. I have not seen this post or the ones that led to it, but if this would be a serious issue, then it would be an issue for ALL tube amplifiers, as the output and interstage transformers are also plate cokes, and with an even more complex resonance pattern. If grid/plate choke has a nasty flavor then an output transformer would be literally unlistenable. As that's not the case, I'm skeptic about generalizing that observation. The market seems to agree with that, today we can buy a wider array of grid chokes than ever before. However, cheap grid/plate chokes with excessive parasitic capacitances are a problem, and do more harm than good to the sound. But that's also true for any part, inadequate quality for a given purpose leads to unmet needs....
@@williammeincke9071 Yes, same time. I'd say though that copper versions sound very good straight out of the box, so do not worry about break in time. I have not heard plasma tweeters myself, but a close friend of mine did, and he was very badly disappointed.
Hi Janos, thanks for this great overview. For the DIY audio enthusiast there is an other trick you can do with resisters that may be interesting. Two examples that are basically variations on the same theme. If you have a DAC with a current output, you can use a current transformer to replace the typical op-amp. The secondary side of the transformer is then terminated with a resister. This serves two purposes. It will show an impedance to the DAC on the primary side, and it converts the current source in to a voltage source on the secondary side. The lower the impedance in which the DAC current output feeds, the better it is for the DAC and the sound quality. So you can make use of this by connecting this up with a stepped attenuator. A similar strategy is valid for a cathode follower. If you have a tube as cathode follower in your pre-amp, then you might as well use it to control the volume. This will result as well in a lower output impedance at lower volumes, just make the cathode resister a stepped attenuator. One word of caution though. Use this only with low power amps. Because a malfunction in the stepped attenuator (or a potmeter for that matter, that will work as well as budget alternative) will result in maximum volume. So this is not recommended for high power amps. To clarify, the stepped attenuator or potmeter is configured as variable shunt, with the wiper tied to the high side.
Thank you Hugo, great tips! ; ) The shunt pot trick is a very good one, I used it with my volume control pots - great way to boost a cheap pot when there's no funds for an expensive high quality one.
Dear Janos,
Thank you very much for your comprehensive video response! I am also going to watch back your earlier videos about this subject. Hopefully I can make a decision afterwards. :)
Interesting that you will soon introduce a new speaker design with baltic berch, which I will follow!
2025 Q1 I will be moving to a apartment, hopefully I can get started on my horn design soon after that, I will keep you posted.
Thanks again!
Good luck for your new home, and enjoy the speaker build! My new speaker will be a transmission line for the biggest (12in) Sonido full range Alnico. ; )
Hi Nick, good luck on your new adventures! May I ask if it was you that had a dac made by Peter van Willenswaard? How are you enjoying it? Have you ever had the chance to compare it with AN? Best regards, Thiago
@ Thanks!
I had the chance to listen for about couple of weeks to a dac made by PvW which sounded very good! I evaluated with a AN Dac3.1x/II, which was slightly more refined, but the AN dac was way more expensive. The PvW was a little bit more dynamic but also slightly more raw. For the price it’s a no brainer.
In east Europe there as another tube dac manufacturer but I can’t remember the name. Something like Abbys. I think Herb Reichert spoke about this brand to
@@nicktube3904 Hi Nick, Thiago, it is Abbas audio in the Ukraine. He is extremely good, doing all the crazy stuff that I do. Well, not crazy, but he has that kind of deep understanding of both electronics and music perception.
@@realworldaudio Abbas, there you go! Thanks
Tube amps are more full range , and have high frequency , time delay. Digital amps are more octave specific. 20% tolerance in components , yields different frequency characteristics as well.
With a DAW, we can now measure , and select a proper digital amplifier for the application. Octave range , distortion bubbles etc. 😊
Thank You Janos. So much great info here. Thanks for taking the time to share your knowledge !!
This is a very interesting and timely video...I'm in the process of designing a tube based pre-amp and power-amp (both monoblocks) to build next year and have been considering how best to deal with a volume control, my thought leading me to perhaps a separate attentuator box in between pre- and power-amp: but I listen at low volumes 95% of the time so most of the volume control won't be used (if that makes sense). I had thought of having no volume control at all, but some means of providing a fixed volume level perhaps via the grid resistor, but now your video has given me lots of things to think about. I too am hoping to build another pair of speakers next year (that was scheduled for this year, but health issues intervened), perhaps a folded Voigt Pipe, not sure yet.
I shall make a video for you! I think I have the solution. ;
Thanks for this informative and helpful info. A few years ago a forum comment led me to the TVC units by Promitheus Audio. Comments on that forum were highly favorable of these TVC units. My question; is it possible and practical to include remote control functionality in a Transformer Volume Control?
It would be a useful feature, but retrofitting and existing unit can be from very hard to possible with a new cabinet. The entry-level Prometheus has space in the chassis for that, but for the big boys there's no space inside for the motor for the remote. (Basically you need to install a motor for the volume selector switch, and the electronics to make the motor work and comminicate with the remote.) It also injects noise to the line AC, that was my main reason to stay away from that. I guess today with LEDs everywhere and SMPSs everywhere, it will not hurt that much an already horrible situation we all are dealing with.
@@realworldaudio I was unaware of the Promitheus as "entry-level" but taking that as a given, who are the "big boys" and why do they not simply expand their chassis to accommodate a remote control motor? As for injecting noise into the AC line, given the state of tech today, I'd bet that can be easily eliminated.
@@geoffreydebrito2653 Handling line AC is worse today than it ever was, by a very very very veeeery long shot. The edge that a TVC brings over resistive or other volume control is easily more than offset by a remote unit installed inside. Also, building AVC/TVC requires a very different skillset from implementing remotes, and I do not know of any AVC tVC maker worth their salt who also builds one with a remote. It's always comfort versus performance... those who can add a remote know little about AVC / TVC, so bother not with that. We can compromise a little at every step and feel not much degradation, but once you start compromising in it adds up and we fall very short. AVC / TVC is for those who want no compromises to the sound, hence the total lack of remote ability from these units.
@@geoffreydebrito2653 Prometheus has entry level and high end TVCs. There's a vast difference in price and size between them. The entry level is flat, small and affordable. The high end units are heavy and enormous. And quite expensive as well.
Hi i just searched abit on the grid chokes what forums do you search for comments on them i found this on diyaudio "
Tekton is probably right.
At one point plate and grid chokes were all the rage in tube amps. Until ONE well known tweeker in Diy circles posted he doesn't like them anymore because they form a resonance circuit and the resulting sound is reflection of that fact. After that pretty much everybody heard those resonances and plate/grid chokes ended up in the landfill" Also have you ever heard a plasma based tweeter?
I have not followed forums for the past 10 years... I quit because trolls taking over on forums, that's the reason I started this channel, to share in a civilized manner. ; ). To me that claim seems to be an over-exaggeration. A resonance with the grid choke would be in most cases very far out of the hearing range. Plus the resonance is also the function of the capacitance that it's reacting with, so I'd say if one has an issue with grid or plate choke related resonances, they have a fundamental issue that they have overlooked in the design and the issue is not the choke but the parasitic capacitance that creates the resonance.
Kind of like saying driving driving a car is not safe because you fall out of the car. However, the car is driven with an open door, and the driver is unaware of the existence of door and use of the seat belt...Drive with a closed door, engage seat belt, and it's safe to drive.
I have not seen this post or the ones that led to it, but if this would be a serious issue, then it would be an issue for ALL tube amplifiers, as the output and interstage transformers are also plate cokes, and with an even more complex resonance pattern. If grid/plate choke has a nasty flavor then an output transformer would be literally unlistenable. As that's not the case, I'm skeptic about generalizing that observation. The market seems to agree with that, today we can buy a wider array of grid chokes than ever before. However, cheap grid/plate chokes with excessive parasitic capacitances are a problem, and do more harm than good to the sound. But that's also true for any part, inadequate quality for a given purpose leads to unmet needs....
How long would you say for tvc or avc break in 100 hours?
More like 1000+
And same for avc? Also have you heard a plasma tweeter?
Br
@@williammeincke9071 Yes, same time. I'd say though that copper versions sound very good straight out of the box, so do not worry about break in time. I have not heard plasma tweeters myself, but a close friend of mine did, and he was very badly disappointed.
@@realworldaudio woaw, do you know which one he heard?
@@williammeincke9071 MBLs top of the line in a system costing more than any car ever made...