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Post by MartinT on Apr 26, 2018 7:07:36 GMT
Something like this? Use two fixed resistors to set the limits and then a stepper with relatively few steps will still give you fine control.
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Post by Deleted on Apr 27, 2018 9:29:02 GMT
I was thinking on these lines and it would solve track in balance.
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Post by Deleted on Apr 27, 2018 9:32:06 GMT
The opto bi directional FET,s can be as low as 10 Ohm. A precision op - amp and a stable volume ref voltage in the master and the other channel should follow it we set the current in the sense resistors to about 1uA and decouple it (not shown) it could work and no nasty Cadmium.
The relay is a after thought when power is off the volume is muted.
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Post by MartinT on Apr 27, 2018 9:43:26 GMT
Can't see the image, Colin.
It's because guests have to login.
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Post by Deleted on Apr 27, 2018 11:43:16 GMT
Can you now
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Post by MartinT on Apr 27, 2018 11:45:02 GMT
Ta!
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Post by miller65 on Apr 27, 2018 13:38:36 GMT
Guys unfortunately the technical stuff is well beyond me , I was working on the basic principal that with a stepped attenuator using only 23 steps a number of those steps will be in 2db steps which appears to be the case with the Tisbury which restricts me fine tuning the volume at the levels I listen at.
I do know the Khozmo with 48 has the majority of listening steps at 1db which presumably will solve my issue , appreciate its not quite that simple as output / input impededance is also a factor ? Also on a similar subject does anyone have any views on the Khozmo attenuators , particularly the shunt design v series ? I was considering the shunt design as it allows upgrades to a craddock z foil resistor.
Thanks
Chris
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Post by Deleted on Apr 27, 2018 16:50:56 GMT
I had some good results with a couple of passive i made in the past using Lin Pots with LFR.. You do have to be very very careful the ratio of Pot to Resistor you choose tho..
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Post by Eduardo Wobblechops on Apr 27, 2018 16:58:12 GMT
Built a passive with Slagle AVC’s which was excellent, best pre I’ve used in my system. Have passed it on, though now have a Tribute AVC which I’ve yet to wire up to try. Hoping for great things from it though, Tribute make some of the best audio transformers on the planet.
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Post by John on Apr 27, 2018 17:19:27 GMT
The slagle is very good
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Post by speedysteve on Apr 27, 2018 22:33:13 GMT
I tried resistor stepped and never liked them. Strangled sounding. I did use a Transformer Volume Control TVC for several years. I improved it with a better switch and even a remote control stepper motor. Cheaper active always sounded, well, active. They imparted something I did not like. TVCs are not perfect but with the right other components they can sound pretty good. For active pre's the Puresounds take some bearing.. it was the L10 that replaced the TVC in the end..
Moving to DSP to do all the X/O stuff etc I required was the big game changer in my system. It's a package deal though. The sum of the active X/O DSP control, time alignment etc beat the sum of DAC or analogue, pre / passive X/Os hands down.
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Post by Deleted on Apr 28, 2018 13:01:00 GMT
MFA Baby reference mk.ii user here.
I’ve not had any Sota active preamps in my system, but I’m very happy with the (lack of) sound it produces. Bass is certainly not anemic; I made sure to match power amps input impedance with my fax very carefully.
Hey presto, one of the few components I’ve zero desire to change.
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Post by Deleted on Apr 28, 2018 19:04:50 GMT
When you think about it, As time goes by things get stripped down to bare bones in the name of sound. They also strip away the body that makes up a good sound.. I dont believe in a million years you can beat the sound of an Active Pre amplifier no matter how much you try.
I think people get side tracked with the attraction of cheap cost & no circuitry
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Post by Deleted on Apr 29, 2018 9:30:46 GMT
When you think about it, As time goes by things get stripped down to bare bones in the name of sound. They also strip away the body that makes up a good sound.. I dont believe in a million years you can beat the sound of an Active Pre amplifier no matter how much you try. I think people get side tracked with the attraction of cheap cost & no circuitry Erm, I beg to differ here. Not all passive solutions are created simply for frugalitys sake. I don’t think there any any absolutes in this hobby and I make my choices based on sound quality, not a lack of circuitry. I don’t care about the topology; I care about the end result. If I’ve followed your logic correctly it seems as if you associate the complexity of a component with it’s quality of sound. Sometimes this may be the case but again, no absolutes. It also depends on the context of the system you’re using it in.
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Post by Deleted on Apr 29, 2018 10:30:43 GMT
But you can ask a hundred Audio nerds why they choose Passive & i can guarantee 2/3rd with say for Simplicity & cheapness even tho some may not admit to the cheap aspect even though that is one of the reasons they choose that route.
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Post by Deleted on Apr 29, 2018 10:54:58 GMT
I don’t agree with that either. No one knows the percentages of who said what (or cares, probably).
I think you’ve also misconstrued their reasoning for desiring simplicity; most people find the passive preamp concept alluring because it’s the nearest thing to “a straight wire with gain” and (if implemented properly) can deliver fantastic purity of sound at a reasonable price.
If it works for them, what’s it to like? Even if it doesn’t, it’s part of this hobby, to explore options and see what works for you.
You’ve made an assumption around their inherent ‘dishonesty’ around price being a factor - what’s your point here?
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Post by Deleted on Apr 29, 2018 11:21:36 GMT
100% the reason i tried Passives,simplicity & cost..what makes me the only one with the idea!
However you are clearly someone who knows best, Ill leave it there.
Toodle pip
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Post by Deleted on Apr 29, 2018 11:33:16 GMT
100% the reason i tried Passives,simplicity & cost..what makes me the only one with the idea! However you are clearly someone who knows best, Ill leave it there. Toodle pip Your reasons for interest are fair; they may not be the same reasons others choose a passive for is all I said; My replies explain my interests in the use of a non active pre is different to yours (mine is for sound quality, not simplicity or cost) and I asked you to explain your broad generalisations. Fuck, why are we so touchy in this hobby?
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Post by Deleted on Apr 29, 2018 17:36:06 GMT
Cost has never been a reason for choosing a good passive, many cost as much as an active pre, its not about price, its about sound quality. For what it's worth the Art Audio VP1 that I use has the best of both worlds with active or passive modes being available. Those at the ASBO will testify to the fact that it's in no way anaemic sounding. However it's woth adding that the passive mode is buffered, so it's loading of the power amp does not vary. Some of the Nelson Pass pres work in this way too. When I made a stepped attenuator pre a few years ago, it sounded pretty good at a certain point on the dial, but not so great at others. Wiring the control up in shunt mode improved the SQ, but fitting a valve buffer really improved matters.
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Post by Deleted on Apr 30, 2018 2:34:50 GMT
Hi Doc, did fitting the tube buffer add a valve like quality to the sound?
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