The No.1 Website for Pro Audio
 Search This Thread  Search This Forum  Search Reviews  Search Gear Database  Search Gear for sale  Search Gearslutz Go Advanced
19" Headroom vs 500 Series Gear
Old 3rd December 2013
  #1
Gear Maniac
 

19" Headroom vs 500 Series Gear

Hello Slutz,

I always hear about people saying "Rackmount gear is better than 500 series gear because it runs off a higher voltage, and therefore has more headroom."

I guess I can see where this would be useful for summing and 2bus processing...
But I don't see why any amount of increased headroom would help me in the recording chain. I mean, my RND 511 pres give 66+6 dB of gain, and it's mega clean all the way through. If I'm using any modern LDC mic, I only even need MAYBE 42 dB of gain before I'm at -20 dBFS RMS (+0 VU) in my daw, peaking at -12.

Why in the heck would I need more headroom than that? Even when recording an SM7b I have more than enough clean gain for anybody to hear a difference...
Old 3rd December 2013
  #2
Lives for gear
I was wondering the same thing. I don't even use more than two or three steps of gain on my Neves.... don't even use the gain knob on APIs even with moving coils... why shouldn't I sell everything and go all 500 series and make a few thousand dollars back?
Old 3rd December 2013
  #3
Lives for gear
1. You don't seem to understand what "headroom" means.
2. For most applications 500 series racks supply enough power, but some devices can take advantage of higher voltage.
Old 3rd December 2013
  #4
Lives for gear
 
emrr's Avatar
The argument that 500 power is inferior is antiquated, and frankly wrong in the majority of cases, if comparing apples to apples. Most things that exist in both 500 and rack versions use the exact same voltage and current. A few don't, but they are the rarity. Many rack pieces that exist only as rack pieces use the same basic power rails (or less!) than any 500 gear.
Old 3rd December 2013
  #5
Lives for gear
I have no experience with 500 series modules, but it seems like it would be easy to run too hot a signal through them for some reason... maybe it's cuz they're so tiny haha I know, that's not technical...
Old 3rd December 2013
  #6
Gear Maniac
 

Quote:
Originally Posted by jetam View Post
1. You don't seem to understand what "headroom" means.
2. For most applications 500 series racks supply enough power, but some devices can take advantage of higher voltage.
I've always been taught that headroom is how far below your signal is from the clipping point, whether it be a hard ceiling (digital) or a gradual one (analog).

With how little gain I need at the preamp stage, I'm not nearly approaching the point of clipping my preamps.

If I'm talking nonsense, then please explain to me what "headroom" is to you.
Old 3rd December 2013
  #7
Lives for gear
Quote:
Originally Posted by Joshua Wise View Post
I've always been taught that headroom is how far below your signal is from the clipping point, whether it be a hard ceiling (digital) or a gradual one (analog).

With how little gain I need at the preamp stage, I'm not nearly approaching the point of clipping my preamps.

If I'm talking nonsense, then please explain to me what "headroom" is to you.
I always thought of headroom as the gain space between background noise and distortion. Multimeter is a great tool here. Learned that from car stereos. Some amp stages get real weird if you exceed their voltage specs by so much as a hair (even if the dB meter is telling you there's headroom) which you can see on an analyzer quite easily. There is an analyzer for the iPhone that is amazing, you can see the weirdness kick in visually as you go over voltage.
Old 3rd December 2013
  #8
Lives for gear
Quote:
Originally Posted by Joshua Wise View Post
I've always been taught that headroom is how far below your signal is from the clipping point, whether it be a hard ceiling (digital) or a gradual one (analog).

With how little gain I need at the preamp stage, I'm not nearly approaching the point of clipping my preamps.

If I'm talking nonsense, then please explain to me what "headroom" is to you.
Yeah, but it depends on the signal level, not on the gain. If you have to use a lot of gain to get a decent level, there isn't much danger of clipping, the problem is when you get a hot level at minimal gain. Hot mics (the ones that require less gain) are more likely to overload the preamp.
Old 3rd December 2013
  #9
Lives for gear
Quote:
Originally Posted by psykostx View Post
I always thought of headroom as the gain space between background noise and distortion. Multimeter is a great tool here. Learned that from car stereos. Some amp stages get real weird if you exceed their voltage specs by so much as a hair (even if the dB meter is telling you there's headroom) which you can see on an analyzer quite easily. There is an analyzer for the iPhone that is amazing, you can see the weirdness kick in visually as you go over voltage.
This is the dynamic range. Headroom is the difference between the clipping level and the nominal or the signal level (depending on the context).
Old 3rd December 2013
  #10
Lives for gear
Quote:
Originally Posted by jetam View Post
This is the dynamic range. Headroom is the difference between the clipping level and the nominal or the signal level (depending on the context).
Ah yes... oopsies... so, how much you can go above nominal voltage before distortion is headroom? Haven't cracked the books in a while.
Old 3rd December 2013
  #11
Lives for gear
 

It's not impossible to generate higher voltage rails off a +/-16v supply. Most designers don't feel the need. And so many 500 modules are about what happens when you drive things into saturation. I can understand it for a console, particularly given the voltage drop you may get, and for the summing buss... but it just seems to be a non-issue for most 500 series stuff.

Sent from my GT-I9300
Old 4th December 2013
  #12
Gear Maniac
 

Quote:
Originally Posted by jetam View Post
Yeah, but it depends on the signal level, not on the gain. If you have to use a lot of gain to get a decent level, there isn't much danger of clipping, the problem is when you get a hot level at minimal gain. Hot mics (the ones that require less gain) are more likely to overload the preamp.
If the mic pre has a "minimum gain" of anything more than +20 dB, then the pre itself has been horribly designed. MY 511 preamp has a minimum gain of -6 dB, so there is no circumstance where the signal from my microphone is too hot even at minimum gain. I don't know of any professional microphones that output at line level +6 dB...

Now, if you're saying that line level is too hot for the preamp, that again is a design flaw, not a format flaw
Old 4th December 2013
  #13
Lives for gear
Quote:
Originally Posted by Joshua Wise View Post
If the mic pre has a "minimum gain" of anything more than +20 dB, then the pre itself has been horribly designed. MY 511 preamp has a minimum gain of -6 dB, so there is no circumstance where the signal from my microphone is too hot even at minimum gain. I don't know of any professional microphones that output at line level +6 dB...

Now, if you're saying that line level is too hot for the preamp, that again is a design flaw, not a format flaw
My point is that clipping occors because of the signal level and that a mic needing higher gain won't decrease the headroom. I'm not talking about what a good preamp is.
Old 4th December 2013
  #14
Gear Addict
 
EisenAudio's Avatar
 

I wish people would stop wasting time discussing this

Quote:
Originally Posted by EisenAudio View Post
As for this high voltage versus low voltage bull****, consider the following and stop worrying about it:

- The max input of most multitrack tape stock is +17dBu (depending on so many variables, I know).
- The max input of most A/D converters (assuming generic calibration and typical analog front ends) is +20dBu, or +22 at best.
- The max I/O of most generic outboard (generic being defined as solid state and transformerless) is between +22 and +26 dBu.
- In 500 series, transformer balanced I/O is pretty common, and with 2:1 and 1:2 step down/up ratios, you can get a +26 dBu max I/O level easily.
- Recording engineers are typically taught (at least in North America) to aim for an average level of +4dBu, with a crest factor (peak above average) of perhaps 12dB. This equates to +16 dBu.

When you convert power supply voltage (DC peak to peak) to theoretical dBu limits (defined as max output level if circuit is capable of rail to rail swing, which most aren't, and without step down/step up transformers on the I/O), the results are as follows:

9V (or +/-4.5V) = +12.27 dBu
12V (or +/-6V) = +14.77 dBu
24V (or +/-12V) = +20.79 dBu
30V (or +/-15V) = +22.73 dBu
32V (or +/-16V) = +23.29 dBu
34V (or +/-17V) = +23.82 dBu
36V (or +/-18V) = +24.31 dBu
40V (or +/-20V) = +25.23 dBu
44V (or +/-22V) = +26.06 dBu
48V (or +/-24V) = +26.81 dBu
60V (or +/-30V) = +28.75 dBu

I will end by saying that not all supplies are created equal. Just because they have the same voltage, doesn't mean they'll sound the same. I'm not surprised when a 500 Series version sounds different than its 19" counterpart, because these are more than likely two different power supply designs using different components and implementation, even when their voltage is exactly the same. I don't blame the voltage, I blame the realities of analog circuit design and human perception. Some 500 Series enclosures have "better" sounding supplies and some 19" enclosures have "better" sounding supplies. Virtually all of them will enable an adequate max output level to record and get the job done.

Furthermore, I have observed that most circuits being adapted for 500 Series (which is 30V or 32V peak to peak) started out on supplies which were pretty close (i.e. between 24V and 34V), because depending on the components and biasing techniques, there is only so much tolerance before a re-design is required. 24V (i.e. Neve) can be easily adapted to 30V (or +/-15V) and achieve even greater headroom. 48V (or +/-24v) going down to 30V is another story, however... But 48V designs are pretty rare. I am speaking of solid state, of course, comparing apples to apples. Vacuum tubes are entirely different realm.
Old 4th December 2013
  #15
Gear Maniac
 

Quote:
Originally Posted by jetam View Post
My point is that clipping occors because of the signal level and that a mic needing higher gain won't decrease the headroom. I'm not talking about what a good preamp is.
Oh okay, I understand what you were trying to say now.

But even so, if I'm recording peaks of +10 dBu, I'm still within the range of having a save signal level for 500 Series modules. I suppose if I'm recording extremely dynamic performances a rackmount preamp would be beneficial. Is that the point you're trying to make?
Old 4th December 2013
  #16
Gear Maniac
 

Thank you EisenAudio, that's very helpful!
Old 4th December 2013
  #17
Lives for gear
 
herecomesyourman's Avatar
+1

The biggest difference is usually when you have something requires more headroom in the 19" original, and then it's CLONED for 500 series where there's less power going on. THAT's when there's less headroom.

This is not the case for everything though.
Old 4th December 2013
  #18
Lives for gear
 
emrr's Avatar
Excellent chart Eisen. I was seeing it in my head, but didn't have a reference handy. Everyone should note that a doubling of voltage buys you another 6 dB of headroom, and that doubling is well beyond the capacity of most circuits. You gotta go up 4 volts to buy even another dB (insignificant to most ears), and that step up from the standard 500 power rails puts you at the operating maximum of most IC's in common audio use.
Old 4th December 2013
  #19
Lives for gear
 
gyraf's Avatar
 

The only real limitation of the 500 rack system is probably it's supply current limitations, which makes it too hard (impossible imo) to implement good vacuum tube technology.

The 51x alliance is a bit better at this - but still not ideal.

Jakob E.
Old 4th December 2013
  #20
Lives for gear
 
herecomesyourman's Avatar
Quote:
Originally Posted by gyraf View Post
The only real limitation of the 500 rack system is probably it's supply current limitations, which makes it too hard (impossible imo) to implement good vacuum tube technology.

The 51x alliance is a bit better at this - but still not ideal.

Jakob E.
The Tube Tech RM system was created so they could get past that limitation. I think it's brilliant and I wish other Tube based designers would embrace it like the 500 series for this reason.
Old 4th December 2013
  #21
Lives for gear
 

Hi
The 'Integrated Circuit' industry standardised on 30 Volts (+-15) for the majority of the op amp designs and most 'spec' sheets refer to this.
Of course circuits don't suddenly 'blow up' exactly on the limit and the maximum 'tolerated' voltages are typically 36, 40 or 44 Volts (total). There are exceptions above this to 60 Volts but these are quite rare).
In the 'specification wars' being able to boast another half dB or so for a finished piece of gear is good so many manufacturers of gear start to 'push the envelope' with an eye to percieved 'improvement' but also increasing risk of component failure (don't push too far!).
16 Volts (total 32) is a happy compromise that gives decent performance and minimal risk of failure together with the reassurance that 'another half a volt or two' won't actually break things.
The '500' series gear is in a similar catagory to 8 bit DOS programmes, technology and applications moved on from their initial design goal and are so 'lacking' in some respects.
There is no technical reason why the supply in a '500' rack has to be seen as 'underpowered' given the specification for 16 Volts, the current capability is not restricted apart from cost of a supply which for the majority of applications will be perfectly suited. A 'simple' mic preamp (from where the '500' started) does not need massive amounts of power however a really complicated piece of processing where SMD parts (miniature) have been used to cram it all into the space may wish to take a fair amount of power.
The size of the box is NOT the limitation of headroom and a circuit presented in 19 inch format using 16 Volt rails originally will (or should) work the same when bashed into the shape that will fit in a '500' rack.
As a note, there should be a 'sticky' which has a glossary of terms used used in the audio world as there are too many who do not understand various terms and the fact that several are 'related' but not necessarily equivalent. Knowledge of this would make life a little simpler when applied with even rudimentary maths capability.
Matt S
Old 6th December 2013
  #22
Gear Addict
 
Kabby's Avatar
Quote:
Originally Posted by Matt Syson View Post
Hi
The 'Integrated Circuit' industry standardised on 30 Volts (+-15) for the majority of the op amp designs and most 'spec' sheets refer to this.
Of course circuits don't suddenly 'blow up' exactly on the limit and the maximum 'tolerated' voltages are typically 36, 40 or 44 Volts (total). There are exceptions above this to 60 Volts but these are quite rare).
In the 'specification wars' being able to boast another half dB or so for a finished piece of gear is good so many manufacturers of gear start to 'push the envelope' with an eye to percieved 'improvement' but also increasing risk of component failure (don't push too far!).
16 Volts (total 32) is a happy compromise that gives decent performance and minimal risk of failure together with the reassurance that 'another half a volt or two' won't actually break things.
The '500' series gear is in a similar catagory to 8 bit DOS programmes, technology and applications moved on from their initial design goal and are so 'lacking' in some respects.
There is no technical reason why the supply in a '500' rack has to be seen as 'underpowered' given the specification for 16 Volts, the current capability is not restricted apart from cost of a supply which for the majority of applications will be perfectly suited. A 'simple' mic preamp (from where the '500' started) does not need massive amounts of power however a really complicated piece of processing where SMD parts (miniature) have been used to cram it all into the space may wish to take a fair amount of power.
The size of the box is NOT the limitation of headroom and a circuit presented in 19 inch format using 16 Volt rails originally will (or should) work the same when bashed into the shape that will fit in a '500' rack.
As a note, there should be a 'sticky' which has a glossary of terms used used in the audio world as there are too many who do not understand various terms and the fact that several are 'related' but not necessarily equivalent. Knowledge of this would make life a little simpler when applied with even rudimentary maths capability.
Matt S
Cool post, thanks
Old 6th December 2013
  #23
Gear Addict
 
Kabby's Avatar
Quote:
Originally Posted by Matt Syson View Post
Hi
The 'Integrated Circuit' industry standardised on 30 Volts (+-15) for the majority of the op amp designs and most 'spec' sheets refer to this.
Of course circuits don't suddenly 'blow up' exactly on the limit and the maximum 'tolerated' voltages are typically 36, 40 or 44 Volts (total). There are exceptions above this to 60 Volts but these are quite rare).
In the 'specification wars' being able to boast another half dB or so for a finished piece of gear is good so many manufacturers of gear start to 'push the envelope' with an eye to percieved 'improvement' but also increasing risk of component failure (don't push too far!).
16 Volts (total 32) is a happy compromise that gives decent performance and minimal risk of failure together with the reassurance that 'another half a volt or two' won't actually break things.
The '500' series gear is in a similar catagory to 8 bit DOS programmes, technology and applications moved on from their initial design goal and are so 'lacking' in some respects.
There is no technical reason why the supply in a '500' rack has to be seen as 'underpowered' given the specification for 16 Volts, the current capability is not restricted apart from cost of a supply which for the majority of applications will be perfectly suited. A 'simple' mic preamp (from where the '500' started) does not need massive amounts of power however a really complicated piece of processing where SMD parts (miniature) have been used to cram it all into the space may wish to take a fair amount of power.
The size of the box is NOT the limitation of headroom and a circuit presented in 19 inch format using 16 Volt rails originally will (or should) work the same when bashed into the shape that will fit in a '500' rack.
As a note, there should be a 'sticky' which has a glossary of terms used used in the audio world as there are too many who do not understand various terms and the fact that several are 'related' but not necessarily equivalent. Knowledge of this would make life a little simpler when applied with even rudimentary maths capability.
Matt S
Cool post, thanks
Old 6th December 2013
  #24
Lives for gear
 
MIKEHARRIS's Avatar
Great explanation MattS....one minor correction...the 500 format began with the 553/550/560...as used in API consoles. The pre was carried in a card cage as a 312..the same card, 325, without input transformer...was used as summing amp/line driver.
When we became a API dealer in 70's the 312 had yet to have it's own front panel.
Old 6th December 2013
  #25
Lives for gear
 

Hi Mike
Thanks for correcting the early history, I am sure someone would chime in with the 'origins' with board or module numbers.
It is these snippets or real information from people who were there at the time that are valuable, as there is a lot of 'hogwash' from 'youngsters' who heard a tale from somewhere who don't research the real info.
Best
Matt S
Old 6th December 2013
  #26
Lives for gear
 
syra's Avatar
I think the main difference in sound between the 19" gear and the 500 stuff comes from the lack of space to use the same components. Every module I've tested in both formats, the 500 series one is always lacking in one way or another.
Old 6th December 2013
  #27
Lives for gear
 
herecomesyourman's Avatar
Quote:
Originally Posted by syra View Post
I think the main difference in sound between the 19" gear and the 500 stuff comes from the lack of space to use the same components. Every module I've tested in both formats, the 500 series one is always lacking in one way or another.
I generally agree with you except for the Dramastic Obsidian. That was the one unit I've tried where I preferred the 500 series version for whatever reason (*I think the side-chain and extra 1.5:1 ratio really improve upon that design. So that's probably what grabbed me, even if 19" is a little "bigger" sounding.) also even though it's much more expensive, you can get a dual mono expander for that unit in the 500 series format. Still I think it's better to investigate this stuff and keep a running tally of what works for you. I (Slightly) prefer the Great River MP-2NV to the 500NV for example, and would rather buy vintage Neves or Neve clones in other formats for sure. I also prefer the A-Designs EM-EQ2 to the EM-PEQ's in the 500 series, it's just a bigger / wider sound with more headroom.

Conversely, API stuff and clones don't really bother me since the 500 series is related to their console designs in terms of power regulation. Also the Great River Harrison 32c EQ is a winner and exclusive to the format. I haven't tried any non-500 series Elysia stuff yet, but I do really dig the Xpressor and Nvelope, even if they prove to be not quite as nice as their 19" counterparts, what I'm getting in terms of space and cost efficiency is pretty huge there too. I don't think I would want to part with them for the 19" versions since it keeps me from having to buy more racks.
Old 6th December 2013
  #28
Lives for gear
 
syra's Avatar
Quote:
Originally Posted by herecomesyourman View Post
I generally agree with you except for the Dramastic Obsidian. That was the one unit I've tried where I preferred the 500 series version for whatever reason (*I think the side-chain and extra 1.5:1 ratio really improve upon that design. So that's probably what grabbed me, even if 19" is a little "bigger" sounding.)
I'm not talking about features - strictly sonics (which you seem to agree w me). From Elysia, Daking, Neves, to AEA or Chandler the 19" stuff sounds better to my ear.
Old 6th December 2013
  #29
Lives for gear
 
herecomesyourman's Avatar
Quote:
Originally Posted by syra View Post
I'm not talking about features - strictly sonics (which you seem to agree w me). From Elysia, Daking, Neves, to AEA or Chandler the 19" stuff sounds better to my ear.
Yeah really I do agree with you (on sonics), things tend to feel a bit smaller with many devices, but sometimes I think it's worth the trade if you can save money and space, and sometimes you either get features you wouldn't get normally...or it's something like the Harrison where it's only available in that format. A lot of the time we're talking about voltage I think. 19" units with a bigger draw who don't have to share a PSU with something else tend to get a bit more headroom than 6-10 units which are sharing a PSU.

You prefer the Elysia stuff in 19" format eh? I wish I could afford to go all 19" there, but I really can't. (I totally trust your word for it though.)
Old 6th December 2013
  #30
Gear Maniac
 

Quote:
Originally Posted by herecomesyourman View Post
Yeah really I do agree with you (on sonics), things tend to feel a bit smaller with many devices, but sometimes I think it's worth the trade if you can save money and space, and sometimes you either get features you wouldn't get normally...or it's something like the Harrison where it's only available in that format. A lot of the time we're talking about voltage I think. 19" units with a bigger draw who don't have to share a PSU with something else tend to get a bit more headroom than 6-10 units which are sharing a PSU.

You prefer the Elysia stuff in 19" format eh? I wish I could afford to go all 19" there, but I really can't. (I totally trust your word for it though.)
EisenAudio's post above pretty much disperses any myth of the voltage differences mattering in any practical situation. If you're hearing differences it's either all in your head, or it's because the 500 series module has a smaller transformer or something, if they couldn't fit the original in the 500 series re-make.
Topic:
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Forum Jump
Forum Jump