Passive pre-amp

[Geoff's Delphi]

Looking to go the Passive Pre Amp route sometime in the future and the one that's caught my eye is the "Icon Audio" Passive. Any thoughts would be appreciated.

[thingfish]

Hi Geoffrey

How much are you willing to spend?

[Bigman80]

Hi Geoff,

Well, to talk plainly, the unit has a Blue Alps potentiometer which has repeatedly been beaten by every Stepped attenuator I have tried.

TKD do a very good value potentiometer which I expect is better thank the alps.

Depends what you want but I'd be wary of spending a lot on a passive with an alps blue in it.

[thingfish]

IMHO there's nowt better than this.......


https://i.imgflip.com/339vvf.jpg (https://imgflip.com/i/339vvf)via Imgflip Meme Generator (https://imgflip.com/memegenerator)

[Geoff's Delphi]

Around the £400, but less would be better.

[RichardA]

I have one in a second system, and agree it seems very good indeed. Completely transparent and without any brightness/leanness that you sometimes hear people complaining about with passives. Might just be a synergistic match of course.

I believe it uses a different implementation to most passives but I don't know what the details are.


IMHO there's nowt better than this.......


https://i.imgflip.com/339vvf.jpg (https://imgflip.com/i/339vvf)via Imgflip Meme Generator (https://imgflip.com/memegenerator)

[Bigman80]

I have one in a second system, and agree it seems very good indeed. Completely transparent and without any brightness/leanness that you sometimes hear people complaining about with passives. Might just be a synergistic match of course.

I believe it uses a different implementation to most passives but I don't know what the details are.Stepped attenuator inside. Different construction as you say. IIRC it has coarse and fine adjustment to volume. Less resistors, which is always a good thing.

[Shovel_Knight]

Well, to talk plainly, the unit has a Blue Alps potentiometer which has repeatedly been beaten by every Stepped attenuator I have tried.

TKD do a very good value potentiometer which I expect is better thank the alps.

TKD 2CP-601 conductive plastic pot is what I use in my DIY headphone amplifier. It's a good pot. I expect it to better than the Alps because it's 3 times more expensive, but I haven't compared.

[thingfish]

I have one in a second system, and agree it seems very good indeed. Completely transparent and without any brightness/leanness that you sometimes hear people complaining about with passives. Might just be a synergistic match of course.

I believe it uses a different implementation to most passives but I don't know what the details are.

Go on then Richard................Whats in your 1st system.???

[Bigman80]

TKD 2CP-601 conductive plastic pot is what I use in my DIY headphone amplifier. It's a good pot. I expect it to better than the Alps because it's 3 times more expensive, but I haven't compared.That's the one. Conductive plastic fared better here. Yes it may be 3 times the price but it has to be a better investment.

I do have a £3 conductive plastic pot somewhere and I felt that was better than an alps blue too.

[ReggieB]

Schiit Saga S (https://www.schiit.com/products/saga-s). All of the above ... with remote

[Alex_UK]

Go on then Richard................Whats in your 1st system.???

(yawn)

Why the yawn, Alan? :scratch:

[Pepperamip]

I think Alan likes stiring the pot from what I've been reading from his posts

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[Light Dependant Resistor]

Looking to go the Passive Pre Amp route sometime in the future and the one that's caught my eye is the "Icon Audio" Passive. Any thoughts would be appreciated.

Other types of passive are worth looking at too: https://www.stereo.net.au/forums/topic/260371-2019-stereocoffee-ldr-preattenuator-kit/

[thingfish]

Now now Pep imp be nice....

I simply yawned cause im off of Nightshift and a tad tired.

Relax.

[Pepperamip]

Now now Pep imp be nice....

I simply yawned cause im off of Nightshift and a tad tired.

Relax.Just an observation, I'm fairly relaxed at the mo ta

Sent from my CLT-L09 using Tapatalk

[Geoff's Delphi]

That looks interesting.

[hornucopia]

I second the Stereo Coffee concept.
Working on the KISS principle, I use this into a Pass F3, using a MHDT 'Havana' dac, playing Ocellia Calliope full range speakers.
Oh and for rare CD use a 'doctored' PS1 deck.
Simple, low ingredient-content, high quality sound.

[thingfish]

Kiss.......is a great concept and that should be a passive pre requisite.

But.............

It's more complex than that.....or is it really?

[RichardA]

I get the impression that there are quite people on this forum that have retained various bits of kit over the years and end up using more than one at a time. Its all part of the fun. I certainly fall into that category.
In contrast, there are really very few clowns on AoS though I suspect I might have spotted one recently.

[RichardA]

Apology required from me given subsequent explanation.
Saw initial post and was irked by it.
My mistake.
Sorry.

[Barry]

That's the one. Conductive plastic fared better here. Yes it may be 3 times the price but it has to be a better investment.

I do have a £3 conductive plastic pot somewhere and I felt that was better than an alps blue too.

Go for the best: https://www.cw-industrialgroup.com/Products/Legacy-Products/Sensors/Conductive-Plastic-Rotary-Potentiometer-RCP. They are fitted in the preamps I use.

[Bigman80]

Go for the best: https://www.cw-industrialgroup.com/Products/Legacy-Products/Sensors/Conductive-Plastic-Rotary-Potentiometer-RCP. They are fitted in the preamps I use.Have you compared them to Khozmo or similar Barry?

[Light Dependant Resistor]

Kiss.......is a great concept and that should be a passive pre requisite.

But.............

It's more complex than that.....or is it really?

If you think of a attenuator in terms of being simple and that simplicity to be exactly where the audio path goes - what is the simplest ?
The answer is in the image. A variable resistor with no contacts coupled by light.

[thingfish]

Now that as Spock would say...is Ilogical captain !!!

[Light Dependant Resistor]

Yet it is the simplest in terms of audio path being preserved, and at the same time being a variable attenuator and a switch for inputs in its Off state

[Bigman80]

LDR are proven to add distortion

Simplest isn't the key.

Lowest distortion is where the OP should be aiming.

[Light Dependant Resistor]

And lowest distortion is with a good LDR circuit.

LDR's simply reflect back how good or poorly the anode and cathode are driven, do that well and distortion
disappears, however do that poorly and figures and graphs you are poised to paste, are what results.

What does it take to drive the anode and cathode correctly, is what you need to ask. You also need to ask
yourself why graphs of distortion are not provided with potentiometers passing audio signals ?
https://pinkfishmedia.net/forum/threads/alps-potentiometers-gain-and-distortion.68076/

[Bigman80]

And lowest distortion is with a good LDR circuit.

LDR's simply reflect back how good or poorly the anode and cathode are driven, do that well and distortion
disappears, however do that poorly and figures and graphs you are poised to paste, are what results.

What does it take to drive the anode and cathode correctly, is what you need to ask. You also need to ask
yourself why graphs of distortion are not provided with potentiometers passing audio signals ?
https://pinkfishmedia.net/forum/threads/alps-potentiometers-gain-and-distortion.68076/

Alps and the like do add a modicum of distortion, which is why I moved to Stepped Attenuators.

There is a forum that offers free measurements of HiFi equipment. Why not send them one of your preamps for testing? I'll try and find a link.

Have your Stereo Coffee preamps been tested already?

I am afraid independent testing with published measurements consistently support the claim that LDR's drift over time and add distortion.

[Light Dependant Resistor]

Alps and the like do add a modicum of distortion, which is why I moved to Stepped Attenuators.

There is a forum that offers free measurements of HiFi equipment. Why not send them one of your preamps for testing? I'll try and find a link.

Have your Stereo Coffee preamps been tested already?

I am afraid independent testing with published measurements consistently support the claim that LDR's drift over time and add distortion.

I think you are referring to Audio Science Review - I am nearly ready to send Amir a cased unit to review.
I too thought stepped attenuators were good, which was in 1992 hearing them with Vishay bulk foil resistors
Just as Rob expresses here in the last paragraph https://robmid42.wixsite.com/diyaudiokits/which-ldr-preamp
stepped attenuators are not very high on the list, when compared to LDR's

Both of your presumptions, expressed as fear, are wrong.... which time will prove. There should be a review
at Pink Fish forum in about 3 weeks, sorting through what sounds best.

[Bigman80]

[QUOTE=Light Dependant Resistor;1097858]I think you are referring to Audio Science Review - I am nearly ready to send Amir a cased unit to review.
I too thought stepped attenuators were good, which was in 1992 hearing them with Vishay bulk foil resistors
Just as Rob expresses here in the last paragraph https://robmid42.wixsite.com/diyaudiokits/which-ldr-preamp
stepped attenuators are not very high on the list, when compared to LDR's

Subjective result, which I am not interested in. I am talking facts and figure to support your continued claims

Both of your presumptions, expressed as fear, are wrong.... which time will prove. There should be a review
at Pink Fish forum in about 3 weeks, sorting through what sounds best. Will this be subjective or fact based?


Fear? Of what?

I have nothing to fear from the results of any test as I have no dog in the race. I am merely saying that your continued claims are so far unsubstantiated by any demonstrable fact or figures, that i have been able to find.

If you wish to continue with those claims then you must provide evidence to support your claims, rather than the subjective testimony of fanboys. What is "better" will always differ between different sets of ears. What is measurably better, will not differ.

I sincerely hope that you unit performs the way you say btw. It would only be a good thing for the Hifi community.

[Pepperamip]

Just to chip in here but I found a khozmo (shunt type) not to my liking as a passive preamp.

Now whether that was because I chose the wrong type of khozmo or something wasn't quite right with the specific one I had I don't know but I suspect its not quite the show stopper in passive form

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[Bigman80]

Just to chip in here but I found a khozmo (shunt type) not to my liking as a passive preamp.

Now whether that was because I chose the wrong type of khozmo or something wasn't quite right with the specific one I had I don't know but I suspect its not quite the show stopper in passive form

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Yes. You are not the first to say those words.

The Khozmo Preamp doesn't appear to have the same level of performance as it does when you attach it to a Unity gain buffer of some type. Why this is, I don't know but there are claims that different resistors are used in the Passive units to those used in the solitary SA you can buy alone. Whether that's true, I don't know. Would be good to find out. I 'll ask.

[Pepperamip]

Mine was hand made Ollie so was the same khozmo a diy'er would use in their active preamp build.


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[STD305M]

Just to chip in and confirm that the Khozmo passive has a different attenuator than the one people buy and fit to the dcb1 and other preamps.

S

[Bigman80]

Mine was hand made Ollie so was the same khozmo a diy'er would use in their active preamp build.


Sent from my CLT-L09 using TapatalkOh, that's very interesting. So what are you currently using. Don't say LDR! [emoji23]

[Pepperamip]

One of those chines relay passive remote pres and very nice it is too

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[Bigman80]

One of those chines relay passive remote pres and very nice it is too

Sent from my CLT-L09 using TapatalkAh, yes. Had one here for a bit. Good unit for the money.

[Edward]

I have a LDR passive preamp which sounds good to me. Seems to let the music with all its detail flow through unhindered regardless of degree of attenuation.

[Bigman80]

I have a LDR passive preamp which sounds good to me. Seems to let the music with all its detail flow through unhindered regardless of degree of attenuation.

I'm not saying they don't sound good. The one I had here, built by Alan [Firebottle] was good, I enjoyed it and said so.

I am simply disputing the claim they are free of distortion when multiple sources claim otherwise with evidence provided. The values of resistance between two LDR's are rarely, if ever identical and channel balance issues are well known when using LDR's.

If the Audio Science Forum come back with the result that it is free of distortion, I will accept that. They are not biased in any way bu the fact remains that LDR's are flawed, as are almost anything in HiFi.

[Edward]

Hi Oli

I had more in mind the OP's original request for ideas when I posted rather than the technical aspects of passive preamps which this thread has evolved to.

But yes it would be good to read about measured distortion amounts (generally and not only for LDRs), but I also wonder even if some distortion is measured it will be meaningful in an actual listening environment.

I believe it was my LDR pre that Alan brought round to your gaff. Or maybe the smaller one he put together?

atb
Edward

[Bigman80]

Hi Oli

I had more in mind the OP's original request for ideas when I posted rather than the technical aspects of passive preamps which this thread has evolved to.

But yes it would be good to read about measured distortion amounts (generally and not only for LDRs), but I also wonder even if some distortion is measured it will be meaningful in an actual listening environment.

I believe it was my LDR pre that Alan brought round to your gaff. Or maybe the smaller one he put together?

atb
EdwardIf yours was the large one with leds on, then yes it was yours.i was better than the chinese relay IIRC. Like I said, I thought it was an enjoyable listen and totally get why you enjoy it too.

Yes, I understood the relevance to the ops question and I agree that your recommendation is warranted and valid, In that discussion.

Let's see what ASF come back with and let the OP get back to finding a suitable passive pre!

[Light Dependant Resistor]

I'm not saying they don't sound good. The one I had here, built by Alan [Firebottle] was good, I enjoyed it and said so.

I am simply disputing the claim they are free of distortion when multiple sources claim otherwise with evidence provided. The values of resistance between two LDR's are rarely, if ever identical and channel balance issues are well known when using LDR's.

If the Audio Science Forum come back with the result that it is free of distortion, I will accept that. They are not biased in any way bu the fact remains that LDR's are flawed, as are almost anything in HiFi.

Nothing in audio is entirely distortion free. However our hearing has a perspective measuring instruments cannot begin to approach. As example pace rhythm and timing- measure that if you can successfully !
What in measurements makes you want to dance, to begin tapping your feet... so measurements alone, are a tool to be viewed with much scepticism ( some would say hilarity ) .

With LDR's there are poor ways of powering them , and there are really good ways of powering them. Sadly this difference
has not been recognised before. It is my aim for this to change, to prove there are benefits to audio reproduction in audio systems, by recognising these differences.
In the process the poorer ways of powering LDR's will be hopefully permanently forgotten.

[Macca]

Nothing in audio is entirely distortion free. However our hearing has a perspective measuring instruments cannot begin to approach. As example pace rhythm and timing- measure that if you can successfully !
What in measurements makes you want to dance, to begin tapping your feet... so measurements alone, are a tool to be viewed with much scepticism ( some would say hilarity ) .



You could find the reason for any of those characteristics in the measurements, albeit correlation of subjective appreciation and measured performance is not always straightforward.

There isn't some mysterious force that controls foot tapping or whatever operating entirely independently of the parameters of the equipment in use.

Nice try but that dog won't hunt.

[scotty38]

Whether measurements, or what is measured, make any difference to the sound or not may well be irrelevant. However, you can bet your life they're trotted out either positively or negatively depending on whether you're promoting or defending...

[Macca]

Whether measurements, or what is measured, make any difference to the sound or not may well be irrelevant. However, you can bet your life they're trotted out either positively or negatively depending on whether you're promoting or defending...

Even by people who usually say they don't care about the measurements, only what it sounds like! It's a minefield really and I'd advise not venturing in although it seems like we might have gone a couple of hundred yards already.

[Joe]

Even by people who usually say they don't care about the measurements, only what it sounds like! It's a minefield really and I'd advise not venturing in although it seems like we might have gone a couple of hundred yards already.

The difference being that no-one's going to get their legs blown off discussing pre-amps.

[Light Dependant Resistor]

You could find the reason for any of those characteristics in the measurements, albeit correlation of subjective appreciation and measured performance is not always straightforward.

There isn't some mysterious force that controls foot tapping or whatever operating entirely independently of the parameters of the equipment in use.

Nice try but that dog won't hunt.

Entirely I agree, its not straightforward. Measurements cannot presently fully approach what we hear. Here's another one, how does measurement measure sound stage behind, above and forward of speakers?
Measurement fails to qualify properly, all the things we hear in music, rather it presently jumbles it into another language that is hard to interpret. Measurements agreed are a useful tool, but only tell
part of the picture.

[scotty38]

Entirely I agree, its not straightforward. Measurements cannot presently fully approach what we hear. Here's another one, how does measurement measure sound stage behind, above and forward of speakers?
Measurement fails to qualify properly, all the things we hear in music, rather it presently jumbles it into another language that is hard to interpret. Measurements agreed are a useful tool, but only tell
part of the picture.

Agreed, but to Macca's point even if this is the stance somebody takes, if it also measure well those measurements will be promoted. If it doesn't measure well they're irrelevant....

[Edward]

Of course the end result, of listening to music in a particular setting, will be the synergy between all the items in the audio chain ....

:cool:

[Opti-cal]

Of course the end result, of listening to music in a particular setting, will be the synergy between all the items in the audio chain ....

:cool:

As should be applied to every thread of all time!

Stepped attenuation all the way for me. For various reasons but the chief being I think they sound better. Plus you can lock the volume on exact increments which I have found useful for squeezing better dynamics out of different sources and even just different albums. Volume matching has a big effect on my system/s.

Check these out, I've bought source selectors from the seller before and the work is very good. Plus you can spec your requirements RCA/XLR in/out etc and choose your pot/attenuator.

Cheers

https://www.ebay.co.uk/sch/spj-la-luce/m.html?item=254257022379&hash=item3b32e645ab%3Ag%3AVbsAAOSwEMdc-rzA&rt=nc&_trksid=p2047675.l2562

[Lawrence001]

I'm currently listening to my Django TVC into Edward's LP Spirit/ Valab Class A Pass Aleph clone (formerly Tom's) it's a very nice listen, smooth and easy going but detailed with high resolution. Has anyone else tried TVCs? Mine has the S&B transformers inside so basically a music first (expecting a bit of come back on that one!).

There's one on ebay at their moment for about £600 and it's worth it. You might spot mine on a certain sales site or two, but the sale is on hold since I tried this combo!

Sent from my BLN-L21 using Tapatalk

[realysm42]

I'm currently listening to my Django TVC into Edward's LP Spirit/ Valab Class A Pass Aleph clone (formerly Tom's) it's a very nice listen, smooth and easy going but detailed with high resolution. Has anyone else tried TVCs? Mine has the S&B transformers inside so basically a music first (expecting a bit of come back on that one!).

There's one on ebay at their moment for about £600 and it's worth it. You might spot mine on a certain sales site or two, but the sale is on hold since I tried this combo!

Sent from my BLN-L21 using Tapatalk

I’ve been using various MFA TVCs for years now. I’ve heard far costlier solutions but have never felt the need to change what I use. Wide open and resolving, neutral, balanced throughout the frequency range, it delivers all the emotion in the recording.

Not cheap mind although there’s always second hand options about, some great if you’re patient.

[Marco]

Now now Pep imp be nice....

I simply yawned cause im off of Nightshift and a tad tired.

Relax.

Yeah ok, but please refrain from making those sorts of remarks. It's unnecessary and comes across as provocative. Next time you're tired, keep it to yourself!;)

Marco.

[Pepperamip]

For the record it didn't bother me one bit.. I deal with blokes like that all day at work. Water off a ducks back

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[Miller]

Recently had a Dave Slagle Autoformer passive in my system and very impressed having heard various incarnations - transformer-LDR-switched att' etc etc....

That's where my cash would go but I have two passives wired 47 Labs and Western Electric with a specific Bourns pot that just work so well in my kit.

I keep them hanging around as back up to the iFi Pro pre' as Bourns though not a flash audiophile name supply to the medical, industrial and the automotive industry since the 40's with an unbelivable catalog of precision potentiometers.