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Lexicon PCM70: Pan & Circular Delays

FractalAudio

Administrator
Fractal Audio Systems
Moderator
  • The diffusion in the Axe-Fx sounds quite different to the Lexicon. I've confirmed that the diffusion parameter in the PCM70 is not a mix control, but a time control. I measured the length of the diffusion on PCM70s Circular Delays preset, and then matched the length in the Axe-Fx. Finally, I tweaked it slightly by ear to find a value that was less metallic and more like the fluffy diffusion in the PCM70. The Axe-Fx diffusion is much harder sounding, and also has this kind of flanger-esque quality that changes the perceived pitch as the repeats goes on (think a ball rolling in a metal tube). I did my best with this. Want a more accurate diffusion? Stand on Cliffs lawn and yell at him! ;)
Vehemently disagree with this. Dug my PCM70 out of the closet and compared the diffusion to the Axe-Fx III. The Axe-Fx III is vastly superior. The PCM70 sounds metallic and comb-filtered. The Axe-Fx III sounds like a little reverb is added to each delay. You can stand on my lawn and yell all you want but I'm not changing this.
 

guitarnerdswe

Fractal Fanatic
Vehemently disagree with this. Dug my PCM70 out of the closet and compared the diffusion to the Axe-Fx III. The Axe-Fx III is vastly superior. The PCM70 sounds metallic and comb-filtered. The Axe-Fx III sounds like a little reverb is added to each delay. You can stand on my lawn and yell all you want but I'm not changing this.
I don't know if you know, but the Axe Fx is the second part of the Circular Delays clip. I wouldn't describe the PCM70 as metallic or comb-filtered. That's how I would describe the Axe-Fx. Not meaning to argue, but I think the PCM70 sounds much better.

The funny thing is, if I change the diffusion time during the trailing repeats, the Axe sounds way more like the PCM70 all of a sudden. Even small changes bring out this behaviour.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
I don't know if you know, but the Axe Fx is the second part of the Circular Delays clip. I wouldn't describe the PCM70 as metallic or comb-filtered. That's how I would describe the Axe-Fx. Not meaning to argue, but I think the PCM70 sounds much better.

The funny thing is, if I change the diffusion time during the trailing repeats, the Axe sounds way more like the PCM70 all of a sudden. Even small changes bring out this behaviour.
You're entitled to your opinion. I disagree. I'm not using an impulse to compare them, I'm putting audio through them and the Axe-Fx III sounds 100 times better. In my opinion.
 

yeky83

Power User
I don't know if you know, but the Axe Fx is the second part of the Circular Delays clip. I wouldn't describe the PCM70 as metallic or comb-filtered. That's how I would describe the Axe-Fx. Not meaning to argue, but I think the PCM70 sounds much better.

The funny thing is, if I change the diffusion time during the trailing repeats, the Axe sounds way more like the PCM70 all of a sudden. Even small changes bring out this behaviour.
Not sure since it's just impulses... but to me the Axe-Fx's diffusion sounds like diffuse little reverbs while the PCM70's diffusion sounds like some low density simple stuff, and sounds crunchy not "fluffy."
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
Not sure since it's just impulses... but to me the Axe-Fx's diffusion sounds like diffuse little reverbs while the PCM70's diffusion sounds like some low density simple stuff, and sounds crunchy not "fluffy."
Agreed. I designed the Axe-Fx diffusers to sound like little reverbs. I like a little, 10-20%, which makes the echoes slowly turn into a wash. To me the PCM70 goes "brzzzzpppp" on the attack which I don't find pleasant at all.

I've experimented with diffusers for years. I hate all the examples in the literature (i.e. Schroeder allpass sections). I've implemented quite a few out of the papers and they all sound like crap IMO. I tried the allpass cascade in the JCRev algorithm again today and, yup, still sounds as bad as I remember.
 

guitarnerdswe

Fractal Fanatic
Ok, update time!

The settings are now accurate to within 0.05 dB (used to be 0.10 dB).
Tweaked the diffusion a tiny bit.
On the PCM70, the diffusion causes the actual delay times to drift. I figured out a way to capture this.
 
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Tsavo

New Member
These sound great!!

Do you have any suggestions on how to retain the delay relationships relative to each other whilst taking advantage of the tap tempo feature?
 

guitarnerdswe

Fractal Fanatic
These sound great!!

Do you have any suggestions on how to retain the delay relationships relative to each other whilst taking advantage of the tap tempo feature?
Well, the PCM70 couldn't do tap tempo. But, if you want to, look at my old Lukather X88R preset. I think the blocks were tap tempo compatible in it.

Copy those tempo numbers into these new blocks. Just remember to remove the feedback from feedback 4 in the Circular Delays block, and enter it into feedback 1 instead.

That "voice 4" is only there to capture the drifting of the times, which won't work with tap tempo. Don't worry to much about it. The accumulative difference will only be like 50 ms on the 6th round of repeats, which is over 5 seconds after the initial hit (assuming stock delay times).
 

guitarnerdswe

Fractal Fanatic
Updated the blocks to take advantage of the new EQ section added in FW 14.01. The repeats now have a much more accurate frequency response in the high end roll off.
 

Blix

Inspired
Updated the blocks to take advantage of the new EQ section added in FW 14.01. The repeats now have a much more accurate frequency response in the high end roll off.
OP says lasted edited August 19, did you forget to upload the updated blocks?
 

2112

Fractal Fanatic
I just got a PCM81 and loaded it up with a Circular/Pan Delays preset. Side by side with these blocks it's ridiculously close. Great work @guitarnerdswe
 
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