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Post by Blackdawg on May 4, 2020 12:15:21 GMT -6
Hi all, So I started doing this and some sick part of me loves it  Figured I'd share the results as I get more gear and maybe others will want to share theirs as well. First off, huge shout out to Peterson for making these videos, I followed this and it works great. Please use these on how to setup your interface and how to measure your gear: One thing I'll add is to get the v5.2 BETA! It has the better signal generator for doing the level calibration. I decided to do my ML2's first. I finally got a setup to test things going and calibrated my first 2 units which are stock. I used LTLO Rogue5 op amps for now. From there I decided to measure out the filters. I did all freq and -6 and -12dB per octave and did each unit. #001 -6dB  20200503 ML2_001_HPF_LPF_6dB by Monte Nickles Photos, on Flickr |
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Post by Blackdawg on May 4, 2020 12:19:37 GMT -6
-12db  20200503 ML2_001_HPF_LPF_12dB by Monte Nickles Photos, on Flickr #002 -6dB  20200503 ML2_002_HPF_LPF_6dB by Monte Nickles Photos, on Flickr -12dB  20200503 ML2_002_HPF_LPF_12dB by Monte Nickles Photos, on Flickr Very cool to see this. One thing I found interesting is how broad they are. Especially the LPF start to dip down into the high freqs pretty early.  20200503 ML2_002_LPF6dB by Monte Nickles Photos, on Flickr  20200503 ML2_002_LPF12dB by Monte Nickles Photos, on Flickr  20200503 ML2_001_LPF6dB by Monte Nickles Photos, on Flickr  20200503 ML2_001_LPF12dB by Monte Nickles Photos, on Flickr The HPF also gets up pretty high  20200503 ML2_002_HPF6dB by Monte Nickles Photos, on Flickr  20200503 ML2_002_HPF12dB by Monte Nickles Photos, on Flickr  20200503 ML2_001_HPF6dB by Monte Nickles Photos, on Flickr  20200503 ML2_001_HPF12dB by Monte Nickles Photos, on Flickr Very fun to see this and make. I think I will measure my LC25s tonight which will be fun as its proportional Q. |
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grantb
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Post by grantb on May 4, 2020 12:37:07 GMT -6
very cool, I should try this
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Post by Blackdawg on May 6, 2020 1:42:10 GMT -6
Did an LC25 tonight. Very interesting to see how the filters affect stuff. It's really interesting the further you get towards with the low end or the high end how it affects the frequencies beyond that. As in if you are cutting 3.2kHz after the bell there is still almost like a high shelf. Same goes for lower freq selections and down below. Heres some graphs! 25hz  2020505 CAPI LC25 25hz by Monte Nickles Photos, on Flickr 50Hz  2020505 CAPI LC25 50hz by Monte Nickles Photos, on Flickr 100Hz  2020505 CAPI LC25 100hz by Monte Nickles Photos, on Flickr 200Hz  2020505 CAPI LC25 200hz by Monte Nickles Photos, on Flickr 400Hz  2020505 CAPI LC25 400hz by Monte Nickles Photos, on Flickr 800Hz  2020505 CAPI LC25 800hz by Monte Nickles Photos, on Flickr 1.6kHz 2020505 CAPI LC25 800hz by Monte Nickles Photos, on Flickr 3.2kHz  2020505 CAPI LC25 3.2khz by Monte Nickles Photos, on Flickr 6.4kHz  2020505 CAPI LC25 6.4khz by Monte Nickles Photos, on Flickr 12.8kHz  2020505 CAPI LC25 12.8khz by Monte Nickles Photos, on Flickr Then for fun I did two photos of 5 filters each. basically all the ones on the Left side and all the Right side at the same time.  20200505 CAPI LC25_25-100-400-1.6-6.4 by Monte Nickles Photos, on Flickr  20200505 CAPI LC25_50-200-800-3.2-12.8 by Monte Nickles Photos, on Flickr Overall pretty cool! I'll admit, not as tight of a Q as I thought. But very powerful still. I played around with boosting some and cutting others to get some interesting curves. Nothing worth saving but was fun to see how they interact with each other. |
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Post by indiehouse on May 6, 2020 5:25:57 GMT -6
Blackdawg none of the photos are showing up for me.
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Post by Blackdawg on May 6, 2020 9:41:06 GMT -6
Blackdawg none of the photos are showing up for me. Hmm interesting. I'll reupload them to flikr later today. Thanks for the heads up |
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Post by indiehouse on May 6, 2020 10:56:44 GMT -6
Blackdawg none of the photos are showing up for me. Hmm interesting. I'll reupload them to flikr later today. Thanks for the heads up I wonder if it's just a permissions thing with your current host? There's what looks like a Do Not Enter icon where every photo should be. |
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Post by Blackdawg on May 6, 2020 11:00:48 GMT -6
Hmm interesting. I'll reupload them to flikr later today. Thanks for the heads up I wonder if it's just a permissions thing with your current host? There's what looks like a Do Not Enter icon where every photo should be. Highly likely. I just have them on Google Photos and using the url feature of this forum. I'll just move them to Flickr, how I've usually done all photos in the past. Forums are all just so different in how they handle photos these days, can always rely on BB code though. |
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Post by Blackdawg on May 7, 2020 1:59:35 GMT -6
Hmm interesting. I'll reupload them to flikr later today. Thanks for the heads up I wonder if it's just a permissions thing with your current host? There's what looks like a Do Not Enter icon where every photo should be. Photos updated. |
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Post by bluegrassdan on May 14, 2020 21:59:56 GMT -6
REW is how I measure my gear designs. Super useful.
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grantb
Junior Member
Posts: 97
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Post by grantb on May 18, 2020 22:52:39 GMT -6
One thing I'll add is to get the v5.2 BETA! It has the better signal generator for doing the level calibration. I'm waiting for my forum activation right now so I can download the beta. I sincerely hope this is my problem because my SPL & Phase graph on the calibration is terrifying on 5.19. Looks like a seismograph at a Seahawks game. |
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Post by Blackdawg on May 18, 2020 23:10:27 GMT -6
One thing I'll add is to get the v5.2 BETA! It has the better signal generator for doing the level calibration. I'm waiting for my forum activation right now so I can download the beta. I sincerely hope this is my problem because my SPL & Phase graph on the calibration is terrifying on 5.19. Looks like a seismograph at a Seahawks game. Which graph? What are you measuring? Frequency response? Distortion? |
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grantb
Junior Member
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Post by grantb on May 19, 2020 0:43:57 GMT -6
I'm waiting for my forum activation right now so I can download the beta. I sincerely hope this is my problem because my SPL & Phase graph on the calibration is terrifying on 5.19. Looks like a seismograph at a Seahawks game. Which graph? What are you measuring? Frequency response? Distortion? Frequency response and phase. Sound Devices MixPre 10 II. Line out 0 dB trim to line in 0 dB trim, -12 dBFS sweep. It cleans up a little if I do -20 dBFS sweep, but still doesn't look flat like in Peterson's video.
Edit, yeah here's my distortion graph. I must be doing something wrong. |
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Post by Blackdawg on May 19, 2020 1:23:28 GMT -6
Which graph? What are you measuring? Frequency response? Distortion? Frequency response and phase. Sound Devices MixPre 10 II. Line out 0 dB trim to line in 0 dB trim, -12 dBFS sweep. It cleans up a little if I do -20 dBFS sweep, but still doesn't look flat like in Peterson's video.
Edit, yeah here's my distortion graph. I must be doing something wrong.
Yeah something must be off. The mixpre isn't stellar but it's a perfectly lovely interface. Did you do the calibration? |
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grantb
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Post by grantb on May 19, 2020 9:15:29 GMT -6
Frequency response and phase. Sound Devices MixPre 10 II. Line out 0 dB trim to line in 0 dB trim, -12 dBFS sweep. It cleans up a little if I do -20 dBFS sweep, but still doesn't look flat like in Peterson's video.
Edit, yeah here's my distortion graph. I must be doing something wrong.
Yeah something must be off. The mixpre isn't stellar but it's a perfectly lovely interface. Did you do the calibration? That graph is the result of the calibration sweep on 5.19. I'm hoping the new version will fix it once I am able to download. The sweep is much shorter than shown in the video. It's as if it's overloading but by my meters aren't even coming close to clipping.
EDIT, same results on 5.2b52.
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Post by Blackdawg on May 19, 2020 12:28:33 GMT -6
Yeah something must be off. The mixpre isn't stellar but it's a perfectly lovely interface. Did you do the calibration? That graph is the result of the calibration sweep on 5.19. I'm hoping the new version will fix it once I am able to download. The sweep is much shorter than shown in the video. It's as if it's overloading but by my meters aren't even coming close to clipping.
EDIT, same results on 5.2b52.
hmm strange. So you're coming out of one of the mini xlrs and straight back into an input channel yes? Do you have a battery for it? Maybe try that instead of bus power. Phantom power off? |
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grantb
Junior Member
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Post by grantb on May 19, 2020 12:35:16 GMT -6
That graph is the result of the calibration sweep on 5.19. I'm hoping the new version will fix it once I am able to download. The sweep is much shorter than shown in the video. It's as if it's overloading but by my meters aren't even coming close to clipping.
EDIT, same results on 5.2b52.
hmm strange. So you're coming out of one of the mini xlrs and straight back into an input channel yes? Do you have a battery for it? Maybe try that instead of bus power. Phantom power off? Yes, TA-3 out to XLR in, phantom off. The 10 doesn't work on bus power so I'm using the Sound Devices power adapter. I can try battery later but that would suck if it only works on battery.
Edit: User error it seems, I had the analog limiters on. I still don't understand the phase, which says 3.6deg yet appears to show me being out ~90deg at 20Hz. Anyway, sorry to muck up the thread. I hope to post some useful curves for the BT50 when I am confident of my results. Edit 2: distortion still unacceptable Edit 3: coming closer to the conclusion that this device isn't as clean as I thought it was
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Post by Blackdawg on May 19, 2020 17:08:58 GMT -6
hmm strange. So you're coming out of one of the mini xlrs and straight back into an input channel yes? Do you have a battery for it? Maybe try that instead of bus power. Phantom power off? Yes, TA-3 out to XLR in, phantom off. The 10 doesn't work on bus power so I'm using the Sound Devices power adapter. I can try battery later but that would suck if it only works on battery.
Edit: User error it seems, I had the analog limiters on. I still don't understand the phase, which says 3.6deg yet appears to show me being out ~90deg at 20Hz. Anyway, sorry to muck up the thread. I hope to post some useful curves for the BT50 when I am confident of my results.
Edit 2: distortion still unacceptable Edit 3: coming closer to the conclusion that this device isn't as clean as I thought it was
Ahhh the limiters! I always have those off so didn't think of that. I use the Mixpre10 and 6 often for production work. Occasionally music but not often. I think the unit sounds fine, not stellar by any means for music. But acceptable. Be cool to see some BT50 curves! I need to get a pair. On my very long list of kits to get. |
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Post by matt@IAA on May 19, 2020 18:37:03 GMT -6
That phase response doesn’t look unreasonable.
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grantb
Junior Member
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Post by grantb on May 19, 2020 19:31:19 GMT -6
That phase response doesn’t look unreasonable. Yeah I don't think that'll be too much of an issue. I'm more worried about the distortion: Mine looks like what Peterson gets after engaging the CTX transformer color module. |
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Post by matt@IAA on May 19, 2020 20:04:52 GMT -6
If I’m reading that right, it’s 0.1% THD?
That’s high, but not crazy high. What is the dBu level you’re at?
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Post by Blackdawg on May 19, 2020 20:23:03 GMT -6
Yeah that's not awful. Not pristine but for that interface seems likely. My 192 is quieter though. Not sure if I'll fire up that machine today but will share mine tomorrow for sure.
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grantb
Junior Member
Posts: 97
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Post by grantb on May 19, 2020 21:13:41 GMT -6
If I’m reading that right, it’s 0.1% THD? That’s high, but not crazy high. What is the dBu level you’re at? Yeah it's less than 1% THD all together, but I was expecting lower like Peterson's getting from his Apogee. Spec on the SD is <= 0.005% at 1k. I'd like a better picture of the distortion differences in all these CAPI modules I'm building, comparing opamps and such. I'd think any differences will just get eaten by the distortion of the interface loopback in the lows.
I used -12dBfs for that sweep, which is giving me 1.5085 V rms across pins 2-3 which translates to +5.79 dBu. Specs on the SD are +18 dBu out and +14 dBu in.
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Post by matt@IAA on May 19, 2020 22:40:15 GMT -6
I didn’t realize that was your interface loopback. Yeah, that doesn’t seem right at all. Is it better at a much lower level, like -30 dBFS?
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grantb
Junior Member
Posts: 97
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Post by grantb on May 20, 2020 0:01:32 GMT -6
I didn’t realize that was your interface loopback. Yeah, that doesn’t seem right at all. Is it better at a much lower level, like -30 dBFS? Same pretty much.
Edit: same shape of curves I should say. The overall levels of distortion are about 20dB lower but the percent is higher like 6.8%.
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Figured I'd share the results as I get more gear and maybe others will want to share theirs as well. 
