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Burl/Apollo Digital Converters
Old 14th January 2014
  #1
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Burl/Apollo

simple question- do you imagine that I would run into any phasing issues running overheads through a B2 bomber into the spdif input of an Apollo?

I have an Apollo 8 channel now, which I'd like to upgrade to a Symphony 16x16 so that I can use the thunderbolt option which is actually a pcie card over thunderbolt rather than a firewire card over thunderbolt.

However, since I do a ton of vocal tracking, and a ton of overdubs, I can imagine keeping my Apollo and getting a B2 for all those vocals, acoustic guitar, electric guitar, bass, piano, etc. I do a lot of mono or stereo mic'ing of single sources. (I write all my music myself and play all my instruments myself as I'm sure many of us do)

The only time I ever run more than 8 channels is when tracking drums. (9 channels) In fact, the only time I ever run more than 2 channels is when tracking drums. So really, everything I do could run through the Burl except drums, and I've actually been pretty happy with the Apollo.

So if I could run my overheads through the B2 without running into any phase issues I think that would be the more beneficial route for me. What do you think?

thanks.
Old 14th January 2014
  #2
The chances of the apollo and burl having exactly the same latency times are slim. If you take the precaution of ensuring there are 2-3 transients at the start of every recording you can always then drag the burl track into time.
Old 14th January 2014
  #3
Yes, you will encounter phase problems if you run your overheads through one converter and the rest of the drum mics through another. You can work with another unit over the SPDIF I/O, but you just have to take the latency difference into consideration. In other words, you can easily run separate, isolated tracks through them without a problem.
Old 15th January 2014
  #4
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I'm about to record drums in this exact same scenario. My plan is to use impulses to measure the latency with precision.

My fear is that it still won't resolve it perfectly as the exact latency may be off by a sub-sample amount.

Whatever the case, it ain't gonna stop me from recording the stinkin' drums!


Gregory Scott - ubk
Old 15th January 2014
  #5
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Blending converters is never worth the hassle in my experience. Best to avoid.

I tried to build a half-Burl, half Metric Halo rig and it just gave me a headache. I am now back to pure MH [although I mix to a separate Burl B2] and I'm very happy.

- c
Old 12th February 2014
  #6
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Quote:
Originally Posted by Silver Sonya View Post
Blending converters is never worth the hassle in my experience. Best to avoid.

I tried to build a half-Burl, half Metric Halo rig and it just gave me a headache. I am now back to pure MH [although I mix to a separate Burl B2] and I'm very happy.

- c
Do you mean the phase hassles introduced if using both to track? If so, understandable. I avoid that. But why not use the B2 for overdubs? Just curious, you may have an insight I'm missing.

I'm using Lio & B2. For me, anything that needs more than the Burls 2 tracks goes in via Lio. For all other overdubs-B2 ...& of course mixing to B2.
Use the B2 for a master clock here.
Old 12th February 2014
  #7
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Quote:
Originally Posted by chet.d View Post
Do you mean the phase hassles introduced if using both to track? If so, understandable.
I mean using both brand's DA's for mixing, but yes, same principle.

Never worth the hassle, in my experience. I should have listened to my friend Joel's advice. Don't try to combine converters from different manufacturers unless you have aspirin on hand.

I have kept a Burl B2 ADC for mixdown purposes, but I sold my B2 DAC's. Not because there was anything wrong with the sound, just because the complexity of calculating timing issues wasn't worth the mental effort. Made parallel routing [aux buss compression, etc.] too much of a chore.

This does not reflect anything abou the quality of either the ULN8 or the Burl B2's.

Both are stellar, in my opinion.

- c
Old 15th February 2014
  #8
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I combine a Apollo with a Rosetta 200 for drums all the time via spdif clocked bnc via Apollo ..typically snare top and bottom ..never had a problem
Old 15th February 2014
  #9
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How on earth do you guys thinks this could be a problem? The A to D latency will be something around 2 ms for both converters. They will not differ more than 1 ms. So even if the overhead would be late 1 ms or early one ms this will be the same as putting up the mic 34 cm closer or further away. And guess what. The delay is introduces before your driver and before monitoring and it is fixed. So you will compensate for that already during tracking. You will just place your mic some cm closer or further than you would have done without the additional or missing latency. So there is no problem at all.

PS: there are problems if using DA and AD in Mixdown with Analog Summing, because the delay is introduced after you have aligned everything and parallel Stuff will be out of phase. But that is a completely different situation. In tracking there is no problem using another brand and style of converter three spdif, aesebu or Adat.
Old 15th February 2014
  #10
Gear Nut
 

To put this into a musical context, for everybody is always talking about groove and feel when it comes to latency.
Please don't get that mixed with driver issues and round trip computer latency which can be an issue when tracking. This is just about converter latency.

Let's assume you've got a song with 120 bpm in 4/4.
Let's assume your different converters have looooong different latencies. They differ 3 ms. Which will be a lot more than reality. (Today AD have a typical latency of 2 or 3 ms total so a difference of 3 is really unlikely)
Again. This is only the hardware latency normally found in today boxes.

At 120 4/4 one quarter note is 500 ms which makes 3 ms a 1/664th note. Do you really think that your bass player or singer being late or early by a 1/664th note will even be considered laid back or forward. I don't. Not the tiniest bit. This is similar to the bass player on stage being 1 m away from the guitar player. And I never had the situation sitting in a acoustic concert and thinking. Wow this would be so tight if they would just not stand so far away ( 1m) from each other. It so sad that the bass player is alway late by 1m (3ms). More forward would be the option. Maybe I should ask him to step closer 1m. ;-)


So I don't think the latency introduced by the hardware itself could be a problem at all during tracking.

Last edited by Basstian_DE; 15th February 2014 at 10:59 AM.. Reason: Not my native language
Old 23rd July 2014
  #11
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I'm going through the same dilemma right now with the burl and apollo. Love the sound of the Burl, but wan't to avoid phase issues. Did you use the burl for your overheads?

Thanks!
Old 23rd July 2014
  #12
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For everyone poo-pooing the latency thing - yes, you're right, but only as far as it goes. The original question was using different converters on one instrument (drums) *at the same time*. In that situation, moving mics around by a few inches is a big deal. So converter latency will be a big deal. That is, if you can hear it. If you can't, please proceed with your day.
Old 24th July 2014
  #13
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Quote:
Originally Posted by the jinx View Post
I'm going through the same dilemma right now with the burl and apollo. Love the sound of the Burl, but wan't to avoid phase issues. Did you use the burl for your overheads?

Thanks!
no, I did not. Still thinking about it, but in the meantime I'm just making do with 8 channels.
Old 24th July 2014
  #14
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Quote:
Originally Posted by Doc Mixwell View Post
Yes, you will encounter phase problems if you run your overheads through one converter and the rest of the drum mics through another. You can work with another unit over the SPDIF I/O, but you just have to take the latency difference into consideration. In other words, you can easily run separate, isolated tracks through them without a problem.
I realize this is an old thread but can clarify this? I clock an apogee to a burl and use the burl for OH there is never any issues, I have also used apogee ad16x clocked to 2192 on oh with no latency. I have also used the burl and apogees on the same guitar amp and never had any phase shift.

Your OH mics are inherently a couple/few feet away from the drums, how could 2 clocked digital converters have greater latency than what is inherently generated by multiple mic distances?? Is the speed of sound faster than the speed of a digital signal?? Are you sure you phase issues aren't just the inherent phase shift cause by mic distance? Even if you use 1 converter for all your drums there is still going to be phase shift, since the mics are at different distances. It cannot be avoided. In fact that is part of what makes a drum kit sound the way it does all miced up with close and distant mics. In analog days we couldn't nudge the OHs, there is no reason to now. even if the converters do cause phase shift it could be comparable to OH mics placed at a greater distance from the drums. Even with ratio micing rules it's still going to have shift ,albeit it slight and still less than digital clocking signal stream.
Old 24th July 2014
  #15
Quote:
Originally Posted by chainrule View Post
I realize this is an old thread but can clarify this? I clock an apogee to a burl and use the burl for OH there is never any issues, I have also used apogee ad16x clocked to 2192 on oh with no latency.

Your OH mics are inherently a couple feet away from the drums, how could 2 clocked digital converters have greater latency than what is inherently generated by mic distance?? Is the speed of sound faster than the speed of a digital signal??
Each AD converter has a measurable latency figure. It is the time it takes to do its job. Different Brands of AD converters have different Latency Times. Even if those differences are 1 sample apart, that is enough to cause a phase related anomaly within your multi-track. You may not hear what I am talking about. You may hear it...I don't know. But please do note that it will not be something that I do in any of my sessions.
Old 24th July 2014
  #16
Quote:
Originally Posted by chainrule View Post
Are you sure you phase issues aren't just the inherent phase shift cause by mic distance? Even if you use 1 converter for all your drums there is still going to be phase shift, since the mics are at different distances. It cannot be avoided.
In fact that is part of what makes a drum kit sound the way it does all miced up with close and distant mics. In analog days we couldn't nudge the OHs, there is no reason to now. even if the converters do cause phase shift it could be comparable to OH mics placed at a greater distance fron the drums. Even with ratio micing rules it's still going to have shift ,albeit it slight and still less than digtial signal.
I am sure of my findings
I dont need MORE phase shift!!!
It happens when you put similarly related tracks through em...
If you want other non-related or isolated tracks that will be fine.
You will NEVER catch me sending drum mics through different converters...
NEVER ONCE, I would rather go home than do something improperly.
The Latency Related Phase Shift is nothing like actual microphone phase related shift,
You are basically saying its ok to pile **** on top of ****....
I work really hard to make sure my microphones align musically
I DO NOT need more bull**** to fight....
Old 24th July 2014
  #17
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Quote:
Originally Posted by Doc Mixwell View Post
The Latency Related Phase Shift is nothing like actual microphone phase related shift
Phase shift is all the same there is no difference how it occurs. It's all a temporal horizontal sin shift.

If you have a master clock properly configured the delay is simply not audible by human ears. It's not like a computer where the signal is looped back, and even then that is less than .5 ms ...no way can you hear that. That wouldn't even flange.
Old 24th July 2014
  #18
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have a 1-2 bar quarter note reference click at the start of any file...manually adjust by sight zoomed in all the way afterwards to align...what's the big deal?
Old 24th July 2014
  #19
Quote:
Originally Posted by chainrule View Post
Phase shift is all the same there is no difference how it occurs. It's all a temporal horizontal sin shift.

If you have a master clock properly configured the delay is simply not audible by human ears. It's not like a computer where the signal is looped back, and even then that is less than .5 ms ...no way can you hear that. That wouldn't even flange.
A master clock does not change the internal delay, [latency time] of an AD converter. Temporal Horizontal Sin Shift? How do you properly configure a Master clock to change this? I am generally curious about this magic,

I record and mix music.....not math. I don't appreciate you telling me what amount of difference I can discern within my Multitrack recording.

I have enough listening experience with AD/DA converters, recording and mixing to know what happens when you do this.

But thanks for chiming in, asking me why I believe something, and offering your very interesting "what is what, temporal shift" stuff.
Old 24th July 2014
  #20
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Quote:
Originally Posted by Doc Mixwell View Post
A master clock does not change the internal delay, [latency time] of an AD converter.
actually it can in theory
but shouldn't have to. All modern AD units essentially use the same ICs. If there is a difference it would be so subtle I don't know how anyone could possible hear it.

Even with PCs which are very slow compared to the dsprocessing of a standalone converters, PC can accommodate latency at less than .5ms without direct hardware monitoring. That would basically mean the worst a well designed AD converter would be, is still no greater than .5 ms latency.

So even if you had 2 converters the greatest difference in latency they could share would be around 1 ms. No way can anyone hear that. Even a drum machine would barely flange, there is no way a human can hear that small of a delay and still that much of a delay would not happen with modern standalone converters.

Regardless, if there was some greater phase shift from slaving two units it would be like moving the overheads back an inch. In addition, if a converter has an inherent delay then it will still have the same latency internal or externally clocked. So this whole notion that clocking 2 devices causes more delay is inaccurate. If the delay was caused purely by clocking it would actually be more in sync as a slave with an accurate external clock taking control. By all means there probably is some a/d unit that would have a long delay, but it would be a very cheap or very old unit or a slow processing circuitry.

All my rambling aside I can tell you a decent converter clocked to a Burl will not have any additional latency. I've used Lynx aurora, UA 2192, several apogee and Mytek adc96, none of them had greater latency clocked to a burl. Not even a fraction of a ms.
Old 24th July 2014
  #21
Quote:
Originally Posted by chainrule View Post
actually it can in theory
but shouldn't have to. All modern AD units essentially use the same ICs. The difference is so subtle I don;'t know how anyone could possible hear it.

even with PCs which are very slow compared to the processing of a standalone converters, PC can accommodate latency at less than .5ms without direct hardware monitoring. That would basically mean the worst a well designed AD converter would be, is still no greater than .5 ms latency.

So even if you had 2 converters the greatest difference in latency they could share would be around 1 ms. No way can anyone hear that. Even a drum machine would barely flange, there is no way a human can hear that small of a delay and still that much of a delay would not happen with modern standalone converters.
There is an anomaly I can hear when I use two different converters on my drums, or on any multi-microphone setup.

The End,

You are Free to Believe whatever you want.

You are NOT free to "Tell me what I can hear"


...Because you are Grossly Incorrect,

I hear a problem, and won't work improperly............

If YOU cannot hear it,



Have fun,

Enjoy it,







Be well,
Old 24th July 2014
  #22
I can't even quote you anymore...you are all over the place....round and round
The Master Clock is not ADDING latency!!!
The AD converters Have DIFFERENT latencies!!!!!!!!
jeeez....
Old 25th July 2014
  #23
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Quote:
Originally Posted by Doc Mixwell View Post
The AD converters Have DIFFERENT latencies!!!!!!!!
They do have different latencies but it's waaay less than you'd be able to hear. The most it's going to be is a couple ms and that is absolute worst case scenario for a modern standalone unit.

And even if there is latency between two devices and you used one for OH, the delay would be like moving a mic fractionally further away. This wouldn't affect anything in the way you have exaggerated. Especially with OH mics which are always going to be delayed relative to close mics.

I simply asked you to clarify and you had a conniption, it's not that big o deal.......... forget I asked
Old 25th July 2014
  #24
At least we can finally agree they are different. That step seemed pretty hard to climb...

And I don't think I have bionic ears but I know I can hear a difference because I listen.

Furthermore, When you start mixing the tracks the weird phase shift is brought out.
But, you may have never heard how you lost the kick drum or wacked the snare into goofy land....

I will never understand adjusting your ears to this problem, or "aligning" tracks to accomodate

I tried it,
I hated it,
I shunned it,
Old 25th July 2014
  #25
Gear Nut
 

Sorry to correct you. But there is no different phaseshift. Phaseshift is phaseshift, no matter how it is introduced.

But you are right that using a different converter for the OHs makes a differences. What I did not point out in my previous posts is that using a different converter for OHs changes the relationship/correlation between distance and phase. So you can not use the same position to achieve the same phase relation. meaning that probably to match your snare Phase you will have to be closer to the kit than you like if your OHs converter is late, or you will have to be further away that you like if your OHs converter is early. talking about up to 34 cm for worst case scenarios this might make a difference. But for most modern devices this will be a lot less. in the region of 5-10 cm. And I am not really sure that placing you OHs closer or further 5 cm will make such a dramatic difference on what it picks up.

Again. The latency is before monitoring and it is fixed. the Phaserelation is not different from distance introduced phase relation. it only slightly changes the correlation between distance and phase, resulting in a closer or further away phase optimised position. The difference will be something between 1 and 10 cm for modern converters of similar quality. a worst case scenario might be up to 34 cm which can be too much closer or further away for OHs.
Old 25th July 2014
  #26
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Quote:
Originally Posted by Basstian_DE View Post
Sorry to correct you. But there is no different phaseshift. Phaseshift is phaseshift, no matter how it is introduced.
yup it's all based on time. horizontal shift is horizontal shift


Quote:
Originally Posted by Basstian_DE View Post
But you are right that using a different converter for the OHs makes a differences. What I did not point out in my previous posts is that using a different converter for OHs changes the relationship/correlation between distance and phase.
as far as the OH microphones are concerned they are no matter what, going to have slight phase shift relative to the close mics simply based on distance. This would still occur if you used analog tape or even w/ a single converter. Every drum recording, the OH are going to be delayed relative to close mics, it cannot be avoided. But even with additional latency the spacial element of original distance would be retained. It's unlikely anyone would notice the extra delay it would be so small, fraction of a ms with modern A/D units.
Old 26th July 2014
  #27
Do the math.

The speed of sound at sea level is 1,116 feet per second. That means a phase shift of 1 msec is equivalent to moving the overhead mics 1.116 feet. To some of us that would be considered a significant move.

With a 1 msec phase shift it is true that you wouldn't hear a flam, but there would be big changes to the comb filtering in the midrange. At 2 kHz there would be 100% inverted phase. Try inserting a delay plug-in set to 1 msec with wet/dry mix set to 50% to hear it for yourself. With a 0.5 msec phase shift the cancellation would be strongest at 4 kHz - cymbals anyone?

Remember that flangers can use delays well under 1 msec:

Time-based Effects

"Flanging is produced when a signal is delayed a very short amount of time, on the order of .1 to 15 milliseconds, and is mixed with the dry signal. As these two are combined, multiple bands of frequencies are boosted and cut to produce a characteristic "whooshing" sound called comb filtering."

With some pairings of different converters the offsets will be greater or less than with others, so it is entirely possible that chainrule could encounter no audible issues while Doc Mixwell could get nasty comb filtering because he was using a different set up. Too bad the OP never tried it out - that's the only way for him to know for sure...
Old 27th July 2014
  #28
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Quote:
Originally Posted by Trakworx View Post
Do the math.

The speed of sound at sea level is 1,116 feet per second. That means a phase shift of 1 msec is equivalent to moving the overhead mics 1.116 feet. To some of us that would be considered a significant move.
I would say no more than .5 ms but regardless, it's not really like moving the mic 1.116 feet and getting that ambience. Putting a 1ms delay on something is not going to give you ambience like moving a mic 34 cm away


I just looked at one of my old projects where I used 3 different converters on a drum kit, 2192, burl and apogee Rosetta 800. I used 5 OH mics
2 sdc 2 ldc and 1 mono ldc. The 2192 and the b2 had the stereo OHs pairs and the Rosetta had close mics and the mono oh... They OHs were all virtually identical considering the were at different distances inherently based on placement.

While I'm sure you could find 2 converters that are way out of sync they would have to be really old or really cheap designs. The DSP chips and ADCs in those units are virtually the same since they are all made in the same foundries. So the only way there can be a latency is not device dependent but perhaps firmware/software dependent, which would most likely mean an issue in implementation. In that case it basically mean they sukk. The algorithms for conversion have not changed in 60 years, everyone uses the same algorithms. So I don't see how it's possible to have the kind of delays you guys are claiming. I suppose anything is possible
Old 27th July 2014
  #29
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From posts on this site the Burl Mothership (similar?) has a delay of 65 samples on the A/D, at 44.1 this is closer to 1.5ms.

Can you also stop talking about clocking and things being 'out of sync' as this has no relevance to the discussion at hand, which is about sample delay on the A/D of different converters?
Old 27th July 2014
  #30
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Quote:
Originally Posted by londonengineer View Post
From posts on this site the Burl Mothership (similar?) has a delay of 65 samples on the A/D, at 44.1 this is closer to 1.5ms.
I don't have a mothership, but 1.5 seems excessive.

Quote:
Originally Posted by londonengineer View Post
Can you also stop talking about clocking and things being 'out of sync' as this has no relevance to the discussion at hand, which is about sample delay on the A/D of different converters?
I don't think anyone was refer to clocking as it relates to the synchronization of 2 devices and potential delays,
although it certainly could depending on how the 2 devices are talking to each other, what specific sound card you are using could cause issues in some cases.

however what do you think causes latency in any digital unit? it is in fact clocking... as in the edge triggered flavor.
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