Re: TC Impact Twin mods
Not sure how the stereo/mono/side switching is done (transistors, CMOS?)... it can be controlled by the software and the button on the front. However, if you route the audio output directly to 1/2 (instead of going through the mixer),that section gets bypassed completely. Anyway, it is not directly through a hardware switch.
Yes, I realize the that noise on the iXBT test is much lower in magnitude... but it looks similar in nature. My Impact Twin was purchased used and I'm assuming that they tested a brand new one. Perhaps mine has a bit more...
12Bass
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Last Activity: 03-25-2023, 12:54 AM
Joined: 11-04-2015
Location: Saskatoon, SK
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Re: Focusrite Saffire Pro 40 re-cap
FWIW, I've done quite a bit of capacitor comparison testing and can definitely say that there are significant differences in how they sound. One particularly interesting example was in a modified distortion pedal. I tried ceramic, polyester, and polypropylene capacitors of the same value and they all sounded different, depending upon the application. For example, I found that a polypropylene capacitor used in a simple low pass filter sounded "smoother" as in it sent more of the harsh upper harmonic distortion products to ground...Leave a comment:
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Re: TC Impact Twin mods
iXBT.com [URL="https://translate.google.ca/translate?hl=en&ie=UTF8&prev=_t&sl=ru&tl=en&u=http://www.ixbt.com/proaudio/tc-impact-twin.shtml"]reviewed[/URL] the Impact Twin and some similar high frequency noise is evident in their RMAA dynamic range test. Perhaps a bit of switching noise is normal for a compact audio interface with two internal switching power supplies?
If possible, I would like to reduce the switching noise as much as possible, but I'm not sure how to approach that. I did a little...Leave a comment:
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Re: TC Impact Twin mods
Actually, it is the electrolytic capacitor on the preamp gain potentiometer that I changed. Sorry, should have been more clear earlier. The datasheet recommends 6,800uF for THAT 1512, but IIRC TC used 470uF. The replacements are 3,300uF, which was the largest that would fit at the same voltage. I don't have the schematic, so I'm not sure of the surrounding resistance values.Leave a comment:
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Re: TC Impact Twin mods
Thanks!
Actually, the noise is present in both channels, but stronger in the right channel. The second peak appears to be a multiple of 2 times the first. Given that they are -120dB, perhaps it doesn't matter, but they shouldn't be there. If they were audible, I doubt that they would be adding anything desirable to the sound. More air would likely be something like a gentle boost in the highs with a shelving EQ. I've looked at quite a few RMAA tests of other interfaces and most of them are pretty clean at the noise floor. That said,...Leave a comment:
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Re: TC Impact Twin mods
Hey Khron,
I'm hoping you might have an idea what might be causing this noise in my Impact Twin. I suspect that these two peaks (9350Hz & 18,700Hz) may be due to the unit's internal switching power supply. These peaks were present in analog loopback testing which was done before any modifications were made, so they are not a result of the new op amps and bypass capacitors. I've tried adding some ceramic capacitors in parallel with the analog supply electrolytics with minimal improvement.
Any suggestions?...Leave a comment:
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Re: TC Impact Twin mods
Correct, the DIP adapters have another ADA4627-1 on the bottom.
The ADA4627-1 is the best sounding op amp I've found thus far. Oh, those LM4562s are on the 3/4 outputs which are not likely to be used very much. I used OPA2211As to replace the NE5532s because I had them on hand and they sound better, though not as nice as the ADA4627-1; I haven't found a bipolar input op amp that I like as much as that one.
In total, the replacement op amps cost more than I paid for the interface (used).
...
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Re: Focusrite Saffire Pro 40 re-cap
Here's the link showing the non-linearities of various dielectrics: [url]https://web.archive.org/web/20120110144304/http://greygum.net/sbench/sbench102/caps.html[/url]Re: Focusrite Saffire Pro 40 re-cap<...aps.html[/url]Leave a comment:
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Re: Focusrite Saffire Pro 40 re-cap
Some capacitor info here: [url]http://www.reliablecapacitors.com/pickcap.htm[/url]
I had a link showing oscilloscope traces for various dielectric types but cannot find it at the moment. Will post it later if I can find it.
As far as cables go, yes, they can make a significant difference in sound, particularly cable capacitance, when used with something like an electric guitar or bass where they interact with the pickups and alter the frequency response. These effects are easily measurable.Re: Focusrite Saffire Pro 40Leave a comment:
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TC Impact Twin mods
Hey Everyone,
Recently I modified my TC Impact Twin FireWire audio interface.
These units are known to have problems with failing electrolytic capacitors in the power supply section of the circuit, near the voltage regulators. Although I had not yet experienced such problems, I preemptively replaced the existing electrolytics with high quality 105C Panasonic FRs which will hopefully last the life of the unit.
I also replaced the relatively small electrolytic capacitors at the inputs of the two microphone preamps with much larger Panasonic FR electrolytics.... -
Re: Focusrite Saffire Pro 40 re-cap
I've read about the characteristics of various types of capacitors and have seen test results. Electrolytics are among the worst for the signal path. Transparency could probably be quantified and measured somehow, however, what I meant was subjectively audible transparency. As mentioned previously, I did perform RMAA analog loopback tests on my Gina24 both before and after modifications and that testing showed a very obvious decrease in various types of distortion (notably THD and IMD).
Pro 40 RMAA screen capture:...Last edited by 12Bass; 10-31-2017, 07:18 PM.Leave a comment:
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Re: Focusrite Saffire Pro 40 re-cap
Anyone care to provide a stock Impact Twin?
I'd guess that there would be a significant differences in sound between a stock Saffire Pro and Impact Twin due to basic design differences. I did make some subjective A/B comparisons as I modified the two preamp channels on the IT. For example, I compared one modified preamp channel with polypropylene bypass capacitors in parallel with the electrolytics in the signal path with another without added bypass caps. The channel with bypass caps was noticeably clearer, with more apparent...Leave a comment:
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Re: Focusrite Saffire Pro 40 re-cap
A bit tangential, perhaps.... I still haven't modified my Saffire Pro 40. Am still considering replacing some of the electrolytic capacitors and possibly some of the op amps.
However, I did make a number of modifications to my TC Impact Twin, including replacing electrolytic capacitors, adding polypropylene bypass caps, and replacing the original NE5532s with OPA2211As and ADA4627-1s on the 1/2 output. The modified Impact Twin's microphone preamps sound much, much, different than the Saffire Pro's stock preamps. In comparison,...Leave a comment:
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Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?
Thanks! Will have a look.
Am I correct that the Vad is what needs to be adjusted to lower MLL?...Last edited by 12Bass; 03-01-2017, 05:48 AM.Leave a comment:
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Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?
I got the UT50's MLL measurements from several reviews of the television, not from word of mouth. Perhaps it lacks some of the refinement and processing found in the higher models, however, several tests showed that the UT50 was just as good for deep blacks, or at least that what the reviewers found when they tested it. I can find the links and post them if requested. Mine was used a demo for about 4000hrs before I bought it, so I don't know if the black levels were always washed out if they degraded...Last edited by 12Bass; 03-01-2017, 05:46 AM.Leave a comment:
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Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?
Thanks!
Yup, the only pots I can find are Vsus and Vda.
As mentioned previously, I don't understand why the blacks on my set are not dark like they are supposed to be. A variety of instrumented tests have shown that the UT50 is supposed to be essentially equal to the GT/VT50 in a dark room, yet mine is not.
From reading about the earlier Panasonics with rising black levels (e.g. 2009/10), it appears that a regular factory reset through the service menu has...Last edited by 12Bass; 02-24-2017, 04:16 AM.Leave a comment:
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Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?
Revisiting my old thread....
Now that the warranty has expired, I'm thinking about trying some possible modifications to reduce the black level on my TC-P42UT50, recognizing that any potential damage done is completely my own responsibility. Apart from the disappointing black level, I'm otherwise happy with the television.
I'm wondering if it would be possible to install a trimpot on the driver board in order to provide adjustment of the MLL, perhaps in the same part of the circuit...Leave a comment:
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Re: Focusrite 6i6 - upgrade/mod
Better op amps can reduce distortion and improve clarity. I've replaced op amps in my Echo Gina 24 and TC Impact Twin with measurable improvements in RMAA. Also, replacing and/or bypassing electrolytic coupling capacitors with high quality film caps can improve transparency; electrolytics in the signal path are kind of "grungy" sounding. However, bear in mind that surface mount boards can be tricky to work on and if you destroy the traces that might spell the end of your interface.
Probably worth reading the recommendations...Last edited by 12Bass; 07-01-2016, 08:31 AM.Leave a comment:
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Re: Focusrite Saffire Pro 40 re-cap
Hey Khron,
Here's another source on op amp performance which might be of interest: [url]http://www.sg-acoustics.ch/analogue_audio/ic_opamps/[/url]
I find myself a generally skeptical and scientifically-minded person. However, there are times when I think certain people take such an approach too far, such that they are unnecessarily cynical and dismissive. Not all aspects of component performance are easily measured and some people seem eager to dismiss audible differences as pseudoscience when it may be simply that...Leave a comment:
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Hi Khron,
Did you notice any improvement in the MOTU compared with the Focusrite?
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