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passive attenuation
Old 24th January 2007
  #1
Gear Nut
 

passive attenuation

Hope this is the right forum for this question, so here goes:

I realize most on here ( mastering forum ) use very high end(ish) gear for mastering. I do "at home" mastering, mostly for local demo's. I do however own some decent gear, with a signal flow of:

wavelab ( UAD-1 plugs & Waves plugs) -->Benchmark dac-1-->Portico 5043-->Portico 5042-->Aphex compellor-->
Aphex dominator II--> HHB 830 cdr burner.

I monitor thru a pair of Tannoy pbm 8's, as well as a couple of other's just for reference. I currently am running all monitor signal thru a Samson C-control, before it gets to the monitors. I'm quite sure the C-control is mucking up what I should be hearing. It's really quite apparent when I monitor straight from the Benchmark dac-1 to the the monitors. Problem is though,.. I have to go from the dac-1 to my first piece of analog gear, so I can't monitor with it. At this point, my budget simply won't allow an ellaborate monitoring system, eg, another A/D/A , etc.

I've been reading one here about one particular passive attenuator, the 'NHT PRO PVC'. I've also found on line another one from a company called SM pro audio, who has a product called the M-Patch 2.

Both are supposed to be totally transparent, which is what I'm looking for, .. and for a retail of 100ish , they might be just the ticket.

Any thoughts on either product, or any product for that matter?

Thanks,
Marc
Old 24th January 2007
  #2
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Coyoteous's Avatar
 

There's also the Atty - it and the NHT are probably as good as it gets for a c-note. Goldpoint stepped attenuators and the like are 2 to 3 hundred more. Though passive isn't always better - depends on what's on each end. The SPL Volume 2 is active and can be had for about $300... or look into building you own. You could probably get a Vishay conductive plastic dual audio taper pot, connectors, box and a knob for $100 or less that would blow away the Alpha carbons or whatever these cheaper boxes use. I think the audiophiles (DC is growling) are using transformer volume controls these days:

http://www.stevens-billington.co.uk/page102.htm
Old 24th January 2007
  #3
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Riccardo's Avatar
 

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Quote:
Originally Posted by Coyoteous View Post
I think the audiophiles (DC is growling) are using transformer volume controls these days:]
heh

Thanks I didn't know...

I still prefer simple and passive...maybe save up a little bit more and build your own?

Old 24th January 2007
  #4
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I use the M-Patch 2 and except for the not so good headphone amp, it's a great little unit.
Seems transparent enough, but I'm doing a phase cancelation comparison this weekend just to check.
The also have a new product called the Nano Patch, which is just a knob and a mute switch, for even less than the M-Patch 2.
Most purist will tell you to get a high-end one for mastering or to build your own though.

I'll let you know what the phase cancelation turns up.
Old 24th January 2007
  #5
Gear Nut
 

Quote:
Originally Posted by Koed View Post
I use the M-Patch 2 and except for the not so good headphone amp, it's a great little unit.
Seems transparent enough, but I'm doing a phase cancelation comparison this weekend just to check.
The also have a new product called the Nano Patch, which is just a knob and a mute switch, for even less than the M-Patch 2.
Most purist will tell you to get a high-end one for mastering or to build your own though.

I'll let you know what the phase cancelation turns up.
Great,... anxious to hear ( no pun intended ) the results.
Old 25th January 2007
  #6
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The Coleman Audio monitor controllers are a very very big step up in sound quality from your C-Control, are built like tanks but are reasonably priced and will give you the same functionality as your Samson. I use a M3PHmkII in my mastering rig and like it lots - http://www.colemanaudio.com

Best regards,
Steve Berson
Old 25th January 2007
  #7
Gear Head
 

I went through a Presonus Central Station and was unhappy with it. Very flimsy and didn't sound good. Then I went for the Coleman Audio TB4MKII. MUCH BETTER!!. Not pricey for the quality you get and it looks "old school" too which is nice beside my Manleys and Cranesong.
Old 26th January 2007
  #8
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Quote:
Originally Posted by Coyoteous View Post
There's also the Atty - it and the NHT are probably as good as it gets for a c-note. Goldpoint stepped attenuators and the like are 2 to 3 hundred more. Though passive isn't always better - depends on what's on each end.
I think either one would work fine. The trick is just to run as short a cable as practical from attenuator to power amp. Fwiw, I think Carbon sounds much better than conductive plastic. Or CERMET, that one was no bueno.....

Quote:
I think the audiophiles (DC is growling) are using transformer volume controls these days:
Well, of course they are! Why use something that is cheap and works just about perfectly like passive attenuation, when you can add needless complexity and degradation? It's the audiophile way..............................

DC
Old 26th January 2007
  #9
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Quote:
Originally Posted by Riccardo View Post
I still prefer simple and passive...maybe save up a little bit more and build your own?
And it really is easy. Since it's not active, there are no power supply issues, and since it doesn't process, you don't have to lay out a board or anything. A handful of parts, a box, and the most basic soldering skills and you're golden. For parts, try DACT, Shallco, or if you want to get really fancy, DC turned me onto a cool custom solution from Marchand electronics.
Old 26th January 2007
  #10
Gear Nut
 

Quote:
Originally Posted by Koed View Post
I use the M-Patch 2 and except for the not so good headphone amp, it's a great little unit.
Seems transparent enough, but I'm doing a phase cancelation comparison this weekend just to check.
The also have a new product called the Nano Patch, which is just a knob and a mute switch, for even less than the M-Patch 2.
Most purist will tell you to get a high-end one for mastering or to build your own though.

I'll let you know what the phase cancelation turns up.
Buy the way,... where did you purchase your M-Patch 2 ? I searched on the web and none of the supposed dealers have it.

The NHT PRO is backordered until around April, according to their customer service. Still trying to decide between the two. Again, very anxious to hear your findings as far as the phase cancelation test.
Old 27th January 2007
  #11
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lucey's Avatar
you didn't ask but if there's any way around the HHB 830, do it. Just awful

Old 27th January 2007
  #12
Gear Nut
 

Quote:
Originally Posted by lucey View Post
you didn't ask but if there's any way around the HHB 830, do it. Just awful

What exactly are you referring to when you say to work around the HHB 830? What is "just awful"?

I was under the impression that the writing/burning in the HHB was very accurate,.. but the converters were only just O.K. Therefore,... I was/am planning on purchasing an A/D (probably the Benchmark adc-1) to go after my peak limiter, then go digital out into the HHB for writing/burning,... therefore bypassing the HHB's conversion.

I would however still have to monitor analog out of the HHB, again using it's converters. I've been made aware of another unit from Benchmark that acts as a passive splitter of sorts,... which would allow me to send an analog signal to the A/D, as well as to my passive attenuator,.. thus bypassing the HHB's converters all together, .. monitoring without another D/A conversion.
Old 27th January 2007
  #13
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Coyoteous's Avatar
 

Why don't you record back to your workstation and skip the standalone? I use an older HHB (850?) for transferring DAT's, but that's about it. In my experience, you can't make a truly Red Book compliant master from one of these recorders.
Old 27th January 2007
  #14
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Quote:
Originally Posted by dcollins View Post
I think either one would work fine. The trick is just to run as short a cable as practical from attenuator to power amp. Fwiw, I think Carbon sounds much better than conductive plastic. Or CERMET, that one was no bueno.....

Well, of course they are! Why use something that is cheap and works just about perfectly like passive attenuation, when you can add needless complexity and degradation? It's the audiophile way..............................

DC
Okay, I hadn't considered which one would sound better! In the new analog modular synth world (yes, I'm an addict - but that's another story), sealed CP and Cermet are often favored for linearity, thermal stability and rotational life. So, I guess I assumed they would sound better, too... I've gotten real close to the true stepped thing, but choke at impedence, series vs. ladder, smt vs. through hole, etc. (and cost). BTW, what's the Marchand tip, Dave?
Old 28th January 2007
  #15
Gear Nut
 

Quote:
Originally Posted by Coyoteous View Post
Why don't you record back to your workstation and skip the standalone? I use an older HHB (850?) for transferring DAT's, but that's about it. In my experience, you can't make a truly Red Book compliant master from one of these recorders.
I'm really not sure how I could record back to my DAW,...

I'm already playing the 2 trk in wavelab, which is being routed through the analog gear and into the stand alone. I don't think wavelab can play AND record simultaneously, can it? I've really never even considered the possibility.

As stated earlier, I've heard from various sources that the HHB's writer is very accurate/error free. Is this incorrect info?
Old 28th January 2007
  #16
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Quote:
Originally Posted by Coyoteous View Post
BTW, what's the Marchand tip, Dave?
http://www.marchandelec.com/att.html

Second from the bottom, the Shallco sitting on the Styrofoam.

Seems to work.............

DC
Old 28th January 2007
  #17
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Coyoteous's Avatar
 

Quote:
Originally Posted by dcollins View Post
http://www.marchandelec.com/att.html

Second from the bottom, the Shallco sitting on the Styrofoam.

Seems to work.............

DC
- impressive, thanks!
Old 28th January 2007
  #18
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Coyoteous's Avatar
 

Quote:
Originally Posted by rxfit06 View Post
I'm really not sure how I could record back to my DAW,...

I'm already playing the 2 trk in wavelab, which is being routed through the analog gear and into the stand alone. I don't think wavelab can play AND record simultaneously, can it? I've really never even considered the possibility.

As stated earlier, I've heard from various sources that the HHB's writer is very accurate/error free. Is this incorrect info?
Okay, I'll take a shot at this - at the risk of causing the uber-ME's to sprain an eyeball. Yes, I think you're right about WaveLab. Do you have a multitrack app like Pro Tools? You didn't say what kind of interface you have, but ideally you'll need two stereo pairs of digital outs and one pair of inputs for a single analog processing loop and final output monitoring.

I've been a bottom feeding ITB guy for most of the last decade, so this is kind of like a virgin explaining... well, you know. It really all depends on the order of your processing and if your trying to do everything in one swipe. Also, I guess I don't get the two Aphex boxes. Let's just assume that you're going to need more channels of conversion, which you already said.

If I were working with what you've got, I'd play out with plug-in EQ into the Portico pieces and then back in with plug-in limiting and dither to capture as a basic set-up, but you'd need a good AD/DA/Clock combo to do this and monitor with your DAC-1. This doesn't give you much, if any, A/B audition, true bypass, etc. But, you should be able to brew some of that up in your DAW.

I see why you're using the HHB to capture now. Sure, it's fine at recording raw 16 bit data, but you're at the mercy of it's clock and converters. My point was about using the CD's that it generates as masters. There is more to the CD format than "accurate/error free." You really need a computer generated DAO CD to use as a master for duplication/replication.

You're also probably either hitting too low going into the HHB or clipping it's A/D, since you don't have any kind of digital processing or precision metering after your analog chain. You could improve this stage with a good A/D and clock, but what about you're pre analog chain clock? Also, you really should take the HHB disc back into the computer by ripping or digital transfer - trim, index, set pause gaps and burn a real one.

Sorry I couldn't be of much help - too bad BK went dark. Do you have his book?

I guess I need it too - anybody got a used copy for sale cheap? heh
Old 28th January 2007
  #19
Gear Nut
 

Quote:
Originally Posted by Coyoteous View Post
Okay, I'll take a shot at this - at the risk of causing the uber-ME's to sprain an eyeball. Yes, I think you're right about WaveLab. Do you have a multitrack app like Pro Tools? You didn't say what kind of interface you have, but ideally you'll need two stereo pairs of digital outs and one pair of inputs for a single analog processing loop and final output monitoring.

I've been a bottom feeding ITB guy for most of the last decade, so this is kind of like a virgin explaining... well, you know. It really all depends on the order of your processing and if your trying to do everything in one swipe. Also, I guess I don't get the two Aphex boxes. Let's just assume that you're going to need more channels of conversion, which you already said.

If I were working with what you've got, I'd play out with plug-in EQ into the Portico pieces and then back in with plug-in limiting and dither to capture as a basic set-up, but you'd need a good AD/DA/Clock combo to do this and monitor with your DAC-1. This doesn't give you much, if any, A/B audition, true bypass, etc. But, you should be able to brew some of that up in your DAW.

I see why you're using the HHB to capture now. Sure, it's fine at recording raw 16 bit data, but you're at the mercy of it's clock and converters. My point was about using the CD's that it generates as masters. There is more to the CD format than "accurate/error free." You really need a computer generated DAO CD to use as a master for duplication/replication.

You're also probably either hitting too low going into the HHB or clipping it's A/D, since you don't have any kind of digital processing or precision metering after your analog chain. You could improve this stage with a good A/D and clock, but what about you're pre analog chain clock? Also, you really should take the HHB disc back into the computer by ripping or digital transfer - trim, index, set pause gaps and burn a real one.

Sorry I couldn't be of much help - too bad BK went dark. Do you have his book?

I guess I need it too - anybody got a used copy for sale cheap? heh

I use Cubase Sx II , and I use a Presonus Firepod interface.

I currently come out of wavelab via firewire, then s/pdif out of the firepod into the dac-1, bypassing the firepod's converters. After I add the A/D at the end of my analog chain, I will come out of it digitial, and into the HHB digital for writing,.. again bypassing the HHB converters. I also plan on adding a Benchmark device that will allow me to split the signal after the peak limiter, sending a stereo pair to the A/D, and another to a passive monitor/volume controller,... which means I'd be monitoring before any further conversion, which to me seems like it would be more accurate monitoring.

As you can see, the clocking before and after the chain would be controlled via Benchmark's dac-1 and adc-1. Writing to the HHB would be from the adc-1 digital out. Monitoring would be at the end of the analog chain BEFORE any other conversion. Does this all seem logical, or appropriate,.. and please, I'm always eager to learn.

For some reason I'd always assumed that if I imported my master back into wavelab, it would degrade the finished product, no? ... I can see where I would need to do that though in order to get proper pq coding, etc. , which I'll admit I need to learn more about. I mean,.. most of my clients are simply local bands needing to make their demo sound more like a record, but I would like to take my work to the next level at some point if possible.

Sorry I couldn't be of much help - too bad BK went dark. Do you have his book?

I guess I need it too - anybody got a used copy for sale cheap? heh[/QUOTE]
Old 29th January 2007
  #20
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Coyoteous's Avatar
 

Marc, I see where you're coming from. Taking your CD back into the DAW won't cause any degradation, unless there is a problem with the extraction or digital transfer - but these possible problems would probably be events (ticks, etc.), rather than overall degradation.

The main problems I see working with the improved version of your set-up are that you don't truly hear the end of the chain (digitized and dithered to 16 bit) and that you are stuck always doing digital processing first and analog processing second, but it should work. Will the Benchmark ADC dither to 16 bit?

The DAC-1 should isolate jitter from the PreSonus clock and I assume the ADC you want has a good clock. Also, you should get better level setting with the new ADC - but, if you decide to clip the ADC for level, you won't hear the results live. Personally, I'd skip using most of your pieces for most things and stick with the basics - bottomline... go for it!

I just thought of something: you should be able take the digital out of the HHB back into the Presonus digital input to playback and capture in Cubase - or skip the HHB alltogether by having the ADC go straight into the FirePod. You'd also then be clocking off of the Benchmark ADC.
Old 29th January 2007
  #21
Gear Nut
 

Quote:
Originally Posted by Coyoteous View Post
Marc, I see where you're coming from. Taking your CD back into the DAW won't cause any degradation, unless there is a problem with the extraction or digital transfer - but these possible problems would probably be events (ticks, etc.), rather than overall degradation.

The main problems I see working with the improved version of your set-up are that you don't truly hear the end of the chain (digitized and dithered to 16 bit) and that you are stuck always doing digital processing first and analog processing second, but it should work. Will the Benchmark ADC dither to 16 bit?



The DAC-1 should isolate jitter from the PreSonus clock and I assume the ADC you want has a good clock. Also, you should get better level setting with the new ADC - but, if you decide to clip the ADC for level, you won't hear the results live. Personally, I'd skip using most of your pieces for most things and stick with the basics - bottomline... go for it!

I just thought of something: you should be able take the digital out of the HHB back into the Presonus digital input to playback and capture in Cubase - or skip the HHB alltogether by having the ADC go straight into the FirePod. You'd also then be clocking off of the Benchmark ADC.
I see what you mean about not hearing the "true" end of chain at my monitors,.. any idea how I could achieve that? , and yes,.. the ADC does dither to 16.

If taking the digital out of the HHB, into the Firepod, I assume I would do that while the HHB was simply monitoring? If so, time to sell the HHB and get a Plextor drive I guess. Also,.. if coming digital out of the ADC and into the FIrepod,.. my DAW would have to be playing the 2trk in Wavelab, AND Recording in Cubase, correct? ... Don't know if it could handle the additional CPU load or not.
Old 30th January 2007
  #22
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Quote:
Originally Posted by rxfit06 View Post
I see what you mean about not hearing the "true" end of chain at my monitors,.. any idea how I could achieve that? , and yes,.. the ADC does dither to 16.
You would need another DAC and another digital out. With your current set-up and the addition of the ADC, you could get another DAC-1 to hang off the HHB and monitor from there. Otherwise, you would need an interface with more digital I/O than the PreSonus.

Quote:
If taking the digital out of the HHB, into the Firepod, I assume I would do that while the HHB was simply monitoring? If so, time to sell the HHB and get a Plextor drive I guess. Also,.. if coming digital out of the ADC and into the FIrepod,.. my DAW would have to be playing the 2trk in Wavelab, AND Recording in Cubase, correct? ... Don't know if it could handle the additional CPU load or not.
The HHB could be recording, but if you can capture back to your computer, why bother? I don't think you can run both apps at the same time. Multitrack programs, like Cubase, can record and playback at the same time and typically can do many times the number of track you are talking about here. Then once you get your captures, use wavelab for assembly and CD burning. You'll have to see what works and develop routing and workflow that works for you.
Old 30th January 2007
  #23
Gear Nut
 

Quote:
Originally Posted by Coyoteous View Post
You would need another DAC and another digital out. With your current set-up and the addition of the ADC, you could get another DAC-1 to hang off the HHB and monitor from there. Otherwise, you would need an interface with more digital I/O than the PreSonus.



The HHB could be recording, but if you can capture back to your computer, why bother? I don't think you can run both apps at the same time. Multitrack programs, like Cubase, can record and playback at the same time and typically can do many times the number of track you are talking about here. Then once you get your captures, use wavelab for assembly and CD burning. You'll have to see what works and develop routing and workflow that works for you.
I did an experiment last night. I'm trying to get wavelab to do both play and record. My Firepod manual states that in order to receive s/pdif in, I would have to adjust my control panel from internal to s/pdif in. After I do this,.. I can indeed get wavelab to record the existing 2trk "after my analog chain",.. yet all the 2trk files are playing at a slower speed. It does this whether I'm recording or not. After changeing back to internal, all plays at the appropriate speed, but of course I'm now only recording from wavelab's 2trk only, NOT after the analog rack. Changing the sample rates within wavelab's properties makes no difference.

Any ideas?
Old 1st February 2007
  #24
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Quote:
Originally Posted by rxfit06 View Post
I did an experiment last night. I'm trying to get wavelab to do both play and record. My Firepod manual states that in order to receive s/pdif in, I would have to adjust my control panel from internal to s/pdif in. After I do this,.. I can indeed get wavelab to record the existing 2trk "after my analog chain",.. yet all the 2trk files are playing at a slower speed. It does this whether I'm recording or not. After changeing back to internal, all plays at the appropriate speed, but of course I'm now only recording from wavelab's 2trk only, NOT after the analog rack. Changing the sample rates within wavelab's properties makes no difference.

Any ideas?
I don't think WL was intended to do this (anybody?), unless it's changed from earlier versions. I'd try Cubase and see if it works right for you.
Old 1st February 2007
  #25
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Quote:
Originally Posted by Coyoteous View Post
I don't think WL was intended to do this (anybody?), unless it's changed from earlier versions. I'd try Cubase and see if it works right for you.
Yes, after reading through the pdf literature,.. it can indeed perform this function. Here's the interesting part though. After more experimenting,.. I finally got it to work properly.

It seems that after I toggle back and forth between the firepod's control panel,.. changing it from internal, then back to s/pdif,.. it all of a sudden works fine. Yet, if I go and work in Cubase, and come back to wavelab,.. the same problem occurs,.. and more "toggling" from internal to s/pdif is needed to try and get it to work again,.. if at all.

No clue here? Perhaps when I can insert an A/D before the Firepod, and use it's s/pdif out, all will work fine.

By the way,.. while I had the "record back into wavelab" working. I did a quick experiment. I recorded straight to the HHB cdr with one pass,.. then recorded into wavelab,... dithered,.. then burned that and compared the two. To me it seemed like the HHB had more "punch" , for lack of a better word.

Perhaps this wasn't a fair comparison though,.. as I know the HHB truncates down to red book,... and since I was sending a s/pdif out of the HHB,.. I have to assume it was also truncated,.. thus , what I recorded into wavelab was already truncated,.. and then I dithered on top of that,... so that could have been the difference.

Thoughts?
Old 1st February 2007
  #26
Old 1st February 2007
  #27
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Quote:
Originally Posted by grahluk View Post
The second one is definitely unsuitable as the impedance is like 10 times too large!

The impedance for passive should be in the 5k to 600R range, not 100k.

And they use a cheap switch.


DC
Old 2nd February 2007
  #28
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Coyoteous's Avatar
 

Quote:
Originally Posted by dcollins View Post
The second one is definitely unsuitable as the impedance is like 10 times too large!

The impedance for passive should be in the 5k to 600R range, not 100k.
Okay, that's what I wanted to know - 600R = 600 ohms?

Quote:
And they use a cheap switch.


DC
I thought ELMA's were pretty good. So, the Holco/Shallco thing is mating best of breeds?
Old 2nd February 2007
  #29
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10k ohms is common for many off-the-shelf parts, and that will do, but it's as high as you would ever want to go. 100k is definitely too high. 2k5 to 5k is a great range. Be careful of going too much lower if you don't know if the gear in front of it will drive it. 600 ohm is the typical old school audio impedance (back to early telephone days), but some modern mass production stuff isn't very happy there. 2k5 to 5k is a nice balance of competing concerns. DC is a perfect person to get advice from on this subject.
Old 2nd February 2007
  #30
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Quote:
Originally Posted by Coyoteous View Post
So, the Holco/Shallco thing is mating best of breeds?
Yah, the Shallco will last longer than you will.

That photo DC referenced on Marchand's site is actually the very attenuator Phil built for my mastering console!
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