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DBMusic

External Effects And Delay Compensation

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Having a bit of an issue with using my external gear. Here is what I'm trying to do:

I want to create some parallel compression of my percussion tracks using an external EQ and compressor. In the Project Options dialog I have my External Effect set up for the appropriate Send and Return and have detected the latency. I have several percussion tracks all routed to a submix bus (Perc Bus). I have a UAD-1 Plate 140 set up as an effect on the Perc Bus. Off the Perc Bus in have set up an external effect via an Aux send (creating an FX send as an Aux bus named Var-Mu Send and a return tack named Var-Mu Return). I have the Aux send setup Pre fader.

When playing back the Perc Bus and Var-Mu Send with the Plate 140 on, I hear considerable phasing when bring up the Var-Mu Send fader. If I turn off the Plate 140, it gets even worse as I can actually hear a doubling of the percussion tracks.

I guess the routing in Samplitude is a bit confusing to me so I'm not sure what exactly I'm hearing. I have one set of I/O's (1+2) set up that route through a single set of converters in my Crane Song HEDD. I have one out set up as 15+16 that I use for monitoring that runs through a separate converter. All percussion tracks show IN as 1+2 and the OUT as Perc Bus. The Perc Bus shows the IN as 1+2 and OUT as StMast (15+16). The Var-Mu Send has both the IN and OUT set as 1+2. The Var-Mu Return as the IN set to 1+2 and the OUT as StMast. The Send and Return of my External Effect is set up both as 1+2.

Now in Sonar you can set the IN of any track to None. You have no option for Bus IN's because that is defined by what tracks/buses are routed to it. For this configuration in Samplitude I have no choice but to set the IN's of all tracks and buses to 1+2. Since my Aux send is routing out through 1+2, I was wondering if the return through 1+2 wasn't being fed through all these tracks. So I created a dummy 3+4 I/O that was connected to nothing in my audio system and routed all my IN's though it. This made no difference it what I'm hearing.

For another test I simply set up an Aux send off the Perc Bus and added a UAD-1 1176N as an effect. This worked fine and I was able to create, at least to my ears, a perfectly synchronized parallel compression effect.

The conclusion I'm coming to is that there is some rather significant issues with the delay compensation in Samplitude when using an external effect in the way I'm describing. Is this true? I've been trying for a few hours now and can't seem to make this work.

Regards,

DB

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Ok, I take back part of what I said. I set up an Aux send off the Perc bus and added a UAD-1 1176LN to it. Upon playback I'm getting the same phasing affect when it's on and a doubling of the playback with it off. So I removed it from the Aux send completely. When bring up the fader of the Aux send I can hear the doubling affect (like the playback of the Perc bus and the Aux Send are misaligned).

So, I start over and add an Aux send to the Perc Bus and just play it back with no plugins. It plays back fine. Now I add a UAD-1 1176LN to the Aux send bus. Playback is now synchronized.

I do it again and this time add the 1176LN before I play back the empty Aux send. Playback again sounds synchronized.

I start over and add an external effect via an Aux send. The playback is no longer synchronized.

And I'm frustrated and confused...

Regards,

DB

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I was able to eliminate most of the doubling sound when using the external effect configuration by decreasing the ASIO buffer to 128. But I'm still getting the phasing effect that would still indicate lack of synchronization.

Frustrating. These delay compensation issues are what made Sonar such a pain to work with.

Regards,

DB

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I use external digital and analog effects with Sequoia frequently. The delay compensation is almost perfect timing-wise, sometimes there is a totally acceptable phasing, but I have not tried to do parallel external compression and that might be the rub for you. Remember that converters themselves add some characteristics that may make it impossible to do good parallel compression via an analog addition. I can't swear to that without testing it myself.

I did not study your routes, but just check them to make 100% certain that your sends and returns are going via identical routes. But when they don't, instead of phasing you'd hear a distinct delay. Did you ping the external effects in the appropriate delay compensation window?

BK

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I use external digital and analog effects with Sequoia frequently. The delay compensation is almost perfect timing-wise, sometimes there is a totally acceptable phasing, but I have not tried to do parallel external compression and that might be the rub for you. Remember that converters themselves add some characteristics that may make it impossible to do good parallel compression via an analog addition. I can't swear to that without testing it myself.

I did not study your routes, but just check them to make 100% certain that your sends and returns are going via identical routes. But when they don't, instead of phasing you'd hear a distinct delay. Did you ping the external effects in the appropriate delay compensation window?

BK

Parallel external compression may indeed be the rub here. In Samplitude I have no issue with delay compensation when simply routing a track through an external processing loop and recording the return (I found only a 5-6 sample offset from the original track). However, when routing that analog loop via an Aux send off a bus fed several percussion tracks then monitoring the return against the original bus, there is a distinct delay that makes any artful summing of the two impossible. Interesting though, if I place a plugin, in this case a UAD Plate 140 on the original percussion bus and engage it, some additional delay compensation kicks in as then the distinct delay is gone but there is still phasing that is unacceptable.

I did the appropriate setup by pinging external effects and making sure the sends and returns have identical routes (everything is processed through a single HEDD). A little research reveals this is not an uncommon issue when attempting parallel compression via external processing. From what I read it seems that Nuendo and Cubase have the compensation nailed.

I suppose there are some less than elegant workarounds to this as well as other purely digital alternatives. Still, I wish this were possible in Samplitude.

Regards,

DB

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Hi DB,

as far as a sample exact compensation of the round trip is concerned, it should be possible to find out if it is in-exact by any means while adjusting the delay once by hand. You can do that in the FX routing window. Now, the second thing could be instablity. That means, a different delay on each start, or even while running. I don't know what is the specific problem in your case, but generally you will only know if the delay compensation is stable once you have made it exact. And even then, internal (bugs) or external factors (sync, audio interface drivers, etc.) can lead to stability issues.

Cheers,

Sebastian

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Hi DB,

as far as a sample exact compensation of the round trip is concerned, it should be possible to find out if it is in-exact by any means while adjusting the delay once by hand. You can do that in the FX routing window. Now, the second thing could be instablity. That means, a different delay on each start, or even while running. I don't know what is the specific problem in your case, but generally you will only know if the delay compensation is stable once you have made it exact. And even then, internal (bugs) or external factors (sync, audio interface drivers, etc.) can lead to stability issues.

Cheers,

Sebastian

Hi Sebastian,

Adjusting the sample delay in either the primary Perc bus or the Aux Send bus or the Aux Return bus only increases the distinct delay heard on playback. I should emphasize here that the delay I'm concerned with here is playback delay and not recording delay. If I record through the Aux Return bus there is only about an 8 sample delay. However the playback delay is much greater.

As I'm sure you are aware using parallel compression requires some dynamic adjustment of the compression on the Aux Send signal and summing adjustment of the two buses during playback to achieve the right sound and balance. As I have it configured in Samplitude, unless I record the Aux Return first and then use this to sum with the original Perc bus, this will not be possible. This, of course, makes the entire process of using an external compressor for parallel compression possible, but time consuming.

Regards,

DB

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Hi DB,

Not sure how your routing is like. There is more than one possibility to do it. There are however ways to adjust delays in either direction. As far as I remember, FX setup allows for negative values, and so does the track delay in TE. Recording the return and adjusting for the timing then wasn't what I have meant. (It may serve for tracking down direction and magnitudes of the offset, nevertheless...)

Cheers,

Sebastian

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