Analog Attenuator?

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A quality preamp is best even if you only going to use it for changing the volume.

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10 hours ago, Kal Rubinson said:

OK but there are very few of them with more than 2 channels.

 

Yes and for a good reason.

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3 hours ago, The Computer Audiophile said:

This is something that has me hesitant. I exchanged emails today with an engineer, who everybody knows, and he said that under strict conditions passive attenuators can be magical. But, those conditions have to be perfect and unchanged. 
 

He also mentioned very short cables are needed most of the time. 
 

This makes it difficult for those of us with new equipment once in a while. 

 

An engineer, who everybody knows, and that have recipes for magical things – It must be Frank .

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21 minutes ago, sphinxsix said:

Many tears have been shed by megabuck active preamps owners who heard a 10x cheaper passive one performing better 

 

I don’t know anyone who have compared a top active preamp to a cheaper passive one and thought that the later sounded better, much less shared any tears. 

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5 hours ago, The Computer Audiophile said:

I should note that I’m using 40 feet long interconnects from my preamp to my mono amps. The cable is from Gotham. 

 

specs:

Gotham GAC-4/1 11301 ultraPro XLR, starquad balanced single channel 5 times shielded audio cable! Ultraflexible professional audio cable for microphones. 'Double Reussen shield', velvet matte non-light reflecting PVC-jacket material. A unique construction new invented by Gotham design

Connector: Neutrik 3Pin Gold-plated XLR(M/F) Plugs

 

https://www.ghentaudio.com/part/x01.html
 

https://gothamcables.com/en/gothamcables/starquad/11301gac41ultrapro

 

GAC2017page09.pdf 80.27 kB · 0 downloads

 

40 feet long interconnects will degrade the sound quality no matter which type of preamp or attenuator you use. For such long distance I believe balanced interconnects is the most important if the rest of your audio gear has balanced in- and outputs.

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14 hours ago, bbosler said:

 

Really? I think this may be one of the least contentious discussions I've ever been involved in. perhaps you are a bit too sensitive?

 

 

we've never met unless you consider this to be meeting. If you do then you just met one. minus the tears. In addition, there are thousands of people with the funds to do otherwise who prefer a passive over an active. I don't want to make assumptions about your knowledge and background, but the vast majority of those who hold your views have zero knowledge about how electronics actually work. I'm pretty sure the vast majority of them also speak anecdotally having never done the comparison themselves... I have.

 

An active  preamp is simply a passive volume control (potentiometer, stepped attenuator, transformer, etc) and a line level amplifier that may or not have gain. The active stage is usually, almost always, after the volume control to act as a buffer i.e. an impedance matcher that presents a high impedance to the volume control and therefore the source while having a low output impedance to drive the amp. Some put an active stage before and after the volume control and a few put it only before. .  If the source is capable of driving the power amp directly, which many of them are, and the power amp has a relatively high input impedance, which most of them do, then all you may achieve by adding an active preamp is to add coloration. Granted, you may prefer that coloration, but it will be there.

 

Many DACs and other sources are perfectly capable of driving a power amp. Many are designed to do just that with a built in volume control. Most, like the Rossini, control the volume in the digital domain so I prefer to do it after the DAC once the D to A is complete.  DCS even recommends avoiding the use of too much digital attenuation.

 

Kal, I can't imagine a setup where you can't get your sources closer to the front than 30 feet. No need to go into all of the reasons why, but if you are serious about this, and from all I can see you are indeed very serious, of all the compromises we have to make in this hobby running 30 foot cables to my main channels would be at the bottom of my list. If you are locked into that, then you might try the preamps for those channels in the front at the end of the 30 foot run from the source and short cables from the pre to the amps so the attenuation is at the end instead of the beginning. Run a 30 foot cable from your IR repeater to those preamps. The downside is the source has to drive the long cable which may be worse, but you won't know until you try it. You waste a preamp channel doing it that way unless you run a long cable back to the surround channel amp, but a small price to pay for maximum fidelity if it turns out to be better. Interestingly, if you are using the Parasound A31amp up front, the Benchmark preamp has a lower input impedance than the amps so in that regard you are better off with the preamp driving the long cables. .

 

regarding your options, I see that you have none when it comes to multiple input 7.1 AVRs and preamps. Even the ones that have a single set of 7.1 inputs digitize the analog to be processed so for me that would be a non-starter. I would also advise against the custom Placette I proposed since when you decide to move on, and you will move on, you will have a $10K+ boat anchor that isn't heavy enough to serve that purpose. If you decide to try Placette I would get multiple stereo units and use like  the Benchmarks. Your solution of running a bunch of stereo preamps, whether Benchmark or some others,  looks to be the only solution other than the possibility of a pro audio sound console used for mixing. Maybe what  the pros use to mix/create the multichannel recordings ??

 

I don’t think we are discussing the same thing. I/we are not discussing then the source is capable of driving the power amp directly. Connecting a preamp to a top DACs like DCS and MSB always comes with some penalty. What we are discussing is the situation then you have a good DAC that doesn’t have a volume control and pros and cons of different alternatives for changing the volume.

 

I guess that it must mean that you believe that all the manufacturer that makes some of the best amplifiers also has zero knowledge about how electronics actually work. Or why else would they use active preamps instead of passive ones, and not only in their dedicated preamps but also in their top integrated amps.

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1 hour ago, The Computer Audiophile said:

Can you back that up with any other information?
 

40 feet isn’t really that long. Every recording studio I’ve ever been to has cables well over 40 feet. In fact, I’d be surprised if any recording I own was done with shorter cables. 
 

All my interconnects are balanced. 

 

If you do a search on internet you will find a lot of different recommendations. The best IMO is to test this ones and for all yourself, it’s easy if you don’t feel the need to do it blind. I did this more than 25 years ago than it started to come balanced gear for audiophiles. The recording studio was often used as an example on where balanced cables would make a different 😜. We tested short (1,5m ) balanced vs SE cables, then we tested longer (10 meter) balanced vs SE cables and lastly short SE vs long SE then short Balanced vs long balanced. All cables was the same model.

 

We also did a blind test to see if we could distinguish a long balanced from a long SE and a cheap balanced from an expansive balanced. Let say that before that day I was sceptical to both balanced on short cables and that IC could make such a SQ difference.

 

I guess that my experience mean little to you so here is a quote and a few links to back up what I said.

 

Interconnect Conclusions:

One conclusion from these graphs is that when inexpensive interconnects are used, they should be seven feet or shorter. It also shows that optimized interconnects, such as the Microdynamic can be up to 30 feet long before significant phase degradation occurs and more than 100 feet before significant frequency response degradation occurs. The other considerations mentioned previously, including ground-loop noise and poor signal-to-noise environment dictate that it might be prudent to limit these lengths even further. A fudge factor to compensate for these other effects can be applied to get a more realistic prediction of performance. Empirical Audio suggests cutting the guideline in half, which results in inexpensive interconnects having a useful maximum length of about one meter. Optimized high-end interconnects will have a useful maximum length of about 5 meters. Listening tests are highly recommended.

 

http://www.empiricalaudio.com/computer-audio/audio-faqs/short-versus-long-cables

 

https://www.gcaudio.com/tips-tricks/cable-length-and-the-effects-on-sound-quality/

 

https://www.nordost.com/faqs-length.php

 

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41 minutes ago, Kal Rubinson said:

That is not valid argument.  They do not possess any secrets that are not readily accessible to any technically-informed individual but they do have commercial interests that are different from those of the consumer. I take their offerings for what they are but I am wary of accepting (or inferring) their reasons for what they do.

 

That said, I can deal with either an active or a passive solution if it is successful for my situation if it is based on electronic principles and actual performance.  So far, the most practical solution (and the one in use) is a digital control.

 

A beg to differ, what they do and not what they says are valid arguments IMO. The type of design they use is of course what they believe to be the best, and some of them have tried many different designs. On a competitive High End market companies can’t afford not to make as good gear as they can (sorry for the double negative here). All companies do operate on the same market and share the same commercial interests. If you believe that they have some agenda regarding passive/active preamplifying that’s your problem and is noting am interesting in discussing any further.

 

Happy Easter!

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4 hours ago, bbosler said:

I would like to retract my previous assertion that volume control in the digital domain should be avoided. I now have my Rossini hooked directly to my Pass power amp. By selecting the proper output on the Rossini (.2V, .6V, 2V, or 6V) I can stay near the top of the DACs volume range.  More comparing needs to be done but so far so good.. I believe we have a winner

 

I think it’s good that you have tested the volume control in your Rossini. I believe that it’s next to impossible to say if a, dedicated pre or direct to power amp, which is best for all people and in all audio system. What’s best with a DAC like the Rossini may not be true for another quality DAC with a digital volume control. And that’s the problem with too general asked questions or should I say believing what’s best with one DAC in one type of audio system is also the best for all DACs in all audio system. It can be worth to look up what the manufacturer of your gear and others have reached for conclusion and with which preamps, power amps and distance they have between them.

 

https://community.roonlabs.com/t/dcs-bartok-streaming-dac-hp-amp/47510/18

https://www.dcsltd.co.uk/support/can-i-omit-the-preamplifier-and-drive-the-power-amplifiers-directly-from-a-dcs-dac/