And if the execution of construction and materials is excellent?
intact audio has been around for a long time. Consensus is that the magnetics are top-shelf. So let's leave behind the argument that if the implementation is bad then the end result will be bad. The same can be said of an active line stage/buffer, or of a potentiometer, or of anything, really. Bad implementation = bad results. True.
How much does the active circuit cost? For some that could get very expensive, especially if they subscribe to audiophile notions of the specialness of this or that buffer circuit, etc.
Look, I won't argue that a good circuit with high Zin and low Zout (like a stable opamp buffer, or a well-designed cathode follower) will drive or be driven by a typical potentiometer volume control very well. It will, of course. There are even some very inexpensive and small stepped attenuators available from China. I use one in my headphone amp. The Zout from the DAC is about 1k ohms, so I use a 25k stepped attenuator (6.25k max Zout). The Cin of the headphone amp is high, about 150pF. Worst case F3 of the resulting LPF is 170kHz. That's way higher than the output transformer is capable of passing.
The AVC is only worse if it's not implemented well. Of course, implementing it well costs money. Transformers, rectifiers, active devices, passive devices, chassis, wiring, switches, etc. for an excellent active circuit also cost money. Or are you saying that an Altoids tin with a dual opamp inside is all one needs? I won't argue with that either -- it is all you really need!.
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Hi rongon,
Oh boy, here we go.
I can't vouch for intact audio and that is all I said. I can't confirm or deny any claims made by anyone, and I am surely not going to waste time and effort investigating them. Not matter what my findings would be, many might disagree even if I thought they were excellent. All we have are claims and testimony, and as we've seen so many times before, those things can be worth nothing. They also may be legit. What I am saying is exactly what I just said, and it comes down to buyer beware. Fair enough?
Many companies have been around for well over 100 years - and they can change and make crap, or have always made crap. Length of time in business alony means they have a successful business model. I personally know of serveral "high end" audio companies that do not make a good product at all, yet are still highly regarded. So forgive me for not accepting those metrics as proving a good product exists.
Driving a volume control is child's play. Really, not a very demanding job and very easy to do well. The challenge is ... driving unknown cables and unknown input circuits in possibly noisy environments. Cables can vary widely in capacitance, non-linear capacitance, resistance and maybe even inductance for very odd cables. The same can be said for input circuits, plus possible DC currents and of course AC currents from electrical fields that you don't want. Various designs and executed circuits can vary widely in these respects. A passive control element is at a disadvantage here in some circumstances. That's because many times you have to add energy to a signal to avoid distortion. This is a fact of life, and it is why even RS-232, 422, 485 and ethernet circuits are active. That's just data, high and low. Your analogue audio signal is more complicated than the quality of an eye pattern. See what I'm saying?
You don't always need to combat signal degradation (like inside a receiver or integrated amp where wires are not shielded so avoid these effects), but the design of the amplifier input may cause distortion as well. However once you send that signal outside, you are in possible trouble just because. Everything after that depends. The one sure solution is an active stage to drive the cable. This is what I am trying to say. Even the transformer type volume control might be improved in some situations by having an active drive stage.
-Chris
Oh boy, here we go.
I can't vouch for intact audio and that is all I said. I can't confirm or deny any claims made by anyone, and I am surely not going to waste time and effort investigating them. Not matter what my findings would be, many might disagree even if I thought they were excellent. All we have are claims and testimony, and as we've seen so many times before, those things can be worth nothing. They also may be legit. What I am saying is exactly what I just said, and it comes down to buyer beware. Fair enough?
Many companies have been around for well over 100 years - and they can change and make crap, or have always made crap. Length of time in business alony means they have a successful business model. I personally know of serveral "high end" audio companies that do not make a good product at all, yet are still highly regarded. So forgive me for not accepting those metrics as proving a good product exists.
Driving a volume control is child's play. Really, not a very demanding job and very easy to do well. The challenge is ... driving unknown cables and unknown input circuits in possibly noisy environments. Cables can vary widely in capacitance, non-linear capacitance, resistance and maybe even inductance for very odd cables. The same can be said for input circuits, plus possible DC currents and of course AC currents from electrical fields that you don't want. Various designs and executed circuits can vary widely in these respects. A passive control element is at a disadvantage here in some circumstances. That's because many times you have to add energy to a signal to avoid distortion. This is a fact of life, and it is why even RS-232, 422, 485 and ethernet circuits are active. That's just data, high and low. Your analogue audio signal is more complicated than the quality of an eye pattern. See what I'm saying?
You don't always need to combat signal degradation (like inside a receiver or integrated amp where wires are not shielded so avoid these effects), but the design of the amplifier input may cause distortion as well. However once you send that signal outside, you are in possible trouble just because. Everything after that depends. The one sure solution is an active stage to drive the cable. This is what I am trying to say. Even the transformer type volume control might be improved in some situations by having an active drive stage.
-Chris
Yes, that is about it. You have doubts. That's fine. Healthy skepticism is a good thing.
I have one of those AVCs here, so while I have doubts about whether it is a technically superior way of implementing the trivial task of volume control, I have no doubts about what adding that intact AVC did for the sound of my stereo, here, in my living room.
It would be silly and foolish to put an AVC inside a receiver or integrated amp, where the autoformer would be likely to pick up hum, and there are no cable runs to speak of. There's no advantage in that situation, only disadvantages.
Of course! The one sure solution. An active line stage with high input impedance and low output impedance, able to source 10mA into its load, will be able to drive just about any silly length of cable runs, high capacitance and low impedance amp inputs, etc. without slew limiting, loading down and distorting, etc. Without question. In a system with a 'passive preamp' followed by 20 feet of skinny interconnect cables into a power amp with 5k Zin an active buffer will be the correct solution to improve that situation. It will also improve performance (although possibly not audibly) if the cable run is only 6 feet (depending on the output stages of the source devices). Therefore, if recommending a solution that covers all usage situations including those presenting an extremely difficult load after the volume control —yes— an active buffer is the best choice.
I don't see any disagreement here other than over the question of the quality of the construction/materials/design of the intact audio AVCs. Your responses make it look like you're inferring that they are somehow lower in quality than claimed. You don't know that, and that's all you said.
All I said is that they can be a good solution. I did not say they are the very best solution.
However, I will maintain, from personal experience and the experience of several others who use these AVCs, that they are a viable solution, if the rest of the system is friendly to that kind of a solution. I also believe the intact audio AVC I have sounds really good in my setup. (It does pass a squeaky clean 10kHz square wave, incidentally.)
And that's all.
Yu gotta a problem widdat?? Yeah?? What's yer problem widdat? (joke - to be read with a Brooklyn accent)
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LOL!
Yes, I think we basically agree.
For me, I would have to listen to it, and also measure it on the bench in order to say anything definitive. I also have to consider that as good as Intact Audio's product may be, many will "read across" and assume all manufacturers are equivalent. People tend to be lazy and cheap. That combination allows less good products to thrive in the market. So all I can really say about anything is to ***** that product. That also stands for active solutions, you also must examine what you are buying, and I wold also add "no matter what brand name is on the outside"!
- Chris
Yes, I think we basically agree.
For me, I would have to listen to it, and also measure it on the bench in order to say anything definitive. I also have to consider that as good as Intact Audio's product may be, many will "read across" and assume all manufacturers are equivalent. People tend to be lazy and cheap. That combination allows less good products to thrive in the market. So all I can really say about anything is to ***** that product. That also stands for active solutions, you also must examine what you are buying, and I wold also add "no matter what brand name is on the outside"!
- Chris
The model "Passive Selector PS-01" (Miyajima Laboratory) seems to be a good choice - but for me too expensive in Germany (650€) due absence of high quality rotary switches like e.g. ELMA 04 (only standard parts in use):
https://www.miyajima-lab.com/e-others.html
https://www.hifido.co.jp/sold/20-28...=0&LNG=E&OD=2&O=123000&L=50&SD1=0&SD2=0&SD3=0
https://www.hifistatement.net/tests/item/2983-miyajima-laboratory-ps-01?start=0
https://www.canuckaudiomart.com/details/649782457-miyajima-ps-01-passive-preamp/images/3484337/
Rotary switches like those are better for stepped attenuator and input select
https://www.hificollective.co.uk/sites/default/files/wiring_of_all_stepped_attenuators.pdf
https://www.diyaudio.com/community/threads/stepped-attenuator-wiring.335904/
https://www.banzaimusic.com/ELMA-04-1264-20.html
https://www.elma.com/de/products/ro...yelets--12-24-positions--1--4-wafers-12822837
My favorite passive preamps uses parts as to find in the last four from attached images.
this are good examples:
https://web.archive.org/web/2018020...usstereo.com/serious_stereo_attenuator.2.html
https://www.goldpt.com/sa4.html
https://theartofsound.net/forum/showthread.php?49857-FS-Goldpoint-SA4M-47-Passive-Preamp-(Z-Foil-modified)-BARGAIN!!
https://www.miyajima-lab.com/e-others.html
https://www.hifido.co.jp/sold/20-28...=0&LNG=E&OD=2&O=123000&L=50&SD1=0&SD2=0&SD3=0
https://www.hifistatement.net/tests/item/2983-miyajima-laboratory-ps-01?start=0
https://www.canuckaudiomart.com/details/649782457-miyajima-ps-01-passive-preamp/images/3484337/
Rotary switches like those are better for stepped attenuator and input select
https://www.hificollective.co.uk/sites/default/files/wiring_of_all_stepped_attenuators.pdf
https://www.diyaudio.com/community/threads/stepped-attenuator-wiring.335904/
https://www.banzaimusic.com/ELMA-04-1264-20.html
https://www.elma.com/de/products/ro...yelets--12-24-positions--1--4-wafers-12822837
My favorite passive preamps uses parts as to find in the last four from attached images.
this are good examples:
https://web.archive.org/web/2018020...usstereo.com/serious_stereo_attenuator.2.html
https://www.goldpt.com/sa4.html
https://theartofsound.net/forum/showthread.php?49857-FS-Goldpoint-SA4M-47-Passive-Preamp-(Z-Foil-modified)-BARGAIN!!
Attachments
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A passive attenuation device, whilst remaining purely passive for signal paths, needs to have two external assistance circuits ( at least ) , The first to afford lowest volume extremely high series resistance capable of restoring itself to conventional resistance when volume movement occurs The second is to make adjustable typically 8 x the shunt resistance separately, to suit music choice.
My favorite design is a unity gain line stage with high current.
I tested Andrea Ciuffoli's power follower with only 12VDC supply voltage but 1A idle current. Not only for me best preamp ever - independent of used cables to power amp.
For a real live example go to the images in post #1 under
https://www.diyaudio.com/community/...-female-connectors-in-special-outline.245825/
I don't understand, why no commercial available preamps in this kind exist.
From a lot of manufacturers the best approach for better sound is unfortunately very high supply voltage and discrete realized op-amps like Krell's KBL.
Attachments
Ok guys. You might wince at what I am doing with a little project that is still in construction mode, waiting on a part or two. Despite all that, I can only use decent part quality build, and do a couple of experiments. No doubt, all of the previous info in this thread will have to be considered on a case to case basis. Just thought that I might post my progress and impressions during, but most importantly after the build is up and running. To be clear, this photo doesn't really do justice to the fact that the gearing is aluminum, and that the chosen pots are Noble 10k (I also have a pair of 100k Alps in cue). The selector will be a Elma 4 position that might come in today. And FWIW, I am using Manley Labs RCA connectors. The cabling is silver plated copper with shielding for the pots and silver plated copper solid wire will be used for the selector switch. We'll see.
Andrea Ciuffoli's power follower is unity gain power amp, not a preamp. No need to place power amp after it. That completely defeats its purpose.
Nonsense.
Yes, the genuine article describes a power amplifier.
But that does not automatically mean that this unity gain power amp approach is unsuitable for a pre-amplifier resp. line stage applications.
I define the quiescent current with the value of source resistor from IRFP150 (Ube current source).
1A seems to be too much for preamp applications, but I have chosen this value after various listening tests with different coax cables to the power amp.
But that does not automatically mean that this unity gain power amp approach is unsuitable for a pre-amplifier resp. line stage applications.
I define the quiescent current with the value of source resistor from IRFP150 (Ube current source).
1A seems to be too much for preamp applications, but I have chosen this value after various listening tests with different coax cables to the power amp.
My approach on using separate pots!! Should have stuck a patent on it
Suggestion 1 : Use a long central control axle, move the pots near the RCA inputs/outputs, for much shorter cabling.
Suggestion 2 : Use three long axles, face the pots forward with normal knobs, and just a small knob/"pull button" for the centre axle. Adjust Vol. just by turning one of the two pot knobs --> the other pot will follow closely because of the gears.
Now allow a small amount of fore and aft movement for the center axle. Pull/push the "pull button" to disengage/reengage.
Now you've got Balance control capability, omitting the dreaded balance pot and surplus contacts !
Cheers!
If you are satisfied with that power amp used as preamp at 12V supply voltage then I bet you don't measure anything?!
If only I had a crew and a machine shop to go with it. This idea is very similar to what you described. But there are two inside shafts to the front volume split-knobs, one for each pot. This was more common back in the day. Now, to extend those pots to the back of the unit can be done, but it involves two more gears! This wasn't offered with the unit but can be done. The extra set of gears makes the turning correct for volume, but I say skip that and just use pots with no taper, and wire them in reverse.
FWIW, I have already decided to not use the extension shaft since in this instance it shortens nothing as far as signal wire length. What it does save is the total amount of wire used.
The Elma switch that I will be using allows me to not only select the input, but also only the ground from that particular input. It may be a small thing, but may eliminate a ground loop in the signal path.
FWIW, I have already decided to not use the extension shaft since in this instance it shortens nothing as far as signal wire length. What it does save is the total amount of wire used.
The Elma switch that I will be using allows me to not only select the input, but also only the ground from that particular input. It may be a small thing, but may eliminate a ground loop in the signal path.