Suggestions needed for software, interface etc.

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ruffrecords

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Tubetec said:
A new version of Ivan's  E1DE 9038S  is due in any time , it will include an android app thats able to tweek the dac settings via usb, it also has improved performance over generation 2 ,lower noise , lower distortion and wider bandwidth , at 384khz he quotes 5-160000hz +0.1/-3db .
Just goes to show how much easier it is to design a DAC than an ADC. Now if he could make a ADC flat out to 80KHz I would be interested.

Cheers

Ian
 

Tubetec

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Theres not much in the way of ADC out there really ,
There is one old TI evaluation board that looks good ,  PCM4222EVM  ,
It will do up as far as 192khz , every parameter is adjusted by jumper old style
Uses high grade op amps and keeps everything balanced right up to the ADC inputs .
Its around a long long time and doesnt support higher sample rates , theres also around 100 jumpers to set all the parameters:(
It is available from Alied for 175$

TLV320ADC6140 quad-channel 768-kHz Burr-Brown™ audio ADC evaluation module  is also an option ,  it comes with an xmos usb controler card , every parameter is controlable in a very comprehensive software called pure path console.
    http://www.ti.com/lit/ug/sbau335/sbau335.pdf 
the unit can be configured for many different uses
You get either balanced or unbalanced inputs 2v(1v) basic sensitivity, no fancy op amps up front .  200$
A 30$ USb Xmos board and one of the TI ADC chips on a break out board might do more or less the same job ,but without the additional software that allows full access to the dsp /mixer settings easily.

Im very tempted to try one of the E1DE Gen3 DAC's and use it as source for  test signals,  with the calibration available on the chip itself via the app it should be able to offer up an extremely accurate low distortion test signal to well  beyond 100khz.
 

Whoops

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Winston O'Boogie said:
recently managed to acquire a mid 2012, Unibody, last of the upgradeable MacBook Pro i7 quad cores.

Pretty good choice, thats a great machine.
In case you haven't done it, upgrade the RAM to max , it's 16GB max.
And install one or 2 SSD drives, I like to use Samsung Evo

Winston O'Boogie said:
Lastly, if this quad core i7 is simply too long in the tooth, don't hold back, I need to know.

Not the computer itself, the problem is the new MacOS you installed, Apple does a new MacOS version each year so they can turn older and pretty capable computers obsolete.
Your Computer would run better on Mountain Lion, Mavericks, Yosemite.
If you are happy with Catalina, if its stable and it works fine for your needs, resist the urge to update the OS every year.
Actually dont do it

I have a Late 2011 Macbook, I run Mavericks on it, run Protools and REW.
Works great
 

andow

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abbey road d enfer said:
I'm convinced no soundcard-based solution can spare the need for additional hardware.

This  block diagram of your test interface looks really interesting! Is there a PCB for it (or something similar) available?
 

Tubetec

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Heres a few pics of the SSL2 on the inside , along with details of all the IC's used including the Xmos .

 

abbey road d enfer

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UPDATE:
My NI Kompler Audio 2 died on me (negative S/N ratio), so I decided to give Tascam a chance (after 10+ years, I'm a delighted user of my DM4800 mixer). received it this morning.
So far, I found it solves two issues I had with the NI.
  • The noise spectrum is shifted well above 60kHz, and behaves correctly, so it does not fool the RMS detectors in compressors
  • There is no obtrusive limiter on the input
On the minus side, it is significantly bigger.
 

Newmarket

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... so I decided to give Tascam a chance (after 10+ years, I'm a delighted user of my DM4800 mixer). received it this morning.
So far, I found it solves two issues I had with the NI.
  • The noise spectrum is shifted well above 60kHz, and behaves correctly, so it does not fool the RMS detectors in compressors
  • There is no obtrusive limiter on the input
On the minus side, it is significantly bigger.

What TASCAM product did you give a chance ?
 

Gold

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Does it have flat frequency response? I remember someone checking a cheap Tascam interface that had non flat response in the low mids.
 

trobbins

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Oooh, looks like a nice alternative to a Focusrite Scarlett, especially as it has 1Mohm unbalanced inputs with 3.2Vrms capability, and what appears to be a high signal level output (up to 7.7Vrms). Here's hoping you can work out the glitch at 65kHz ! It also looks like it would have reasonable performance down at 2Hz to allow a practical flat line compensation.
 

abbey road d enfer

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Oooh, looks like a nice alternative to a Focusrite Scarlett, especially as it has 1Mohm unbalanced inputs with 3.2Vrms capability
I have found the instrument input has slightly less headroom than the line input. I use an interface that has a calibrated attenuator, so I guess it could work with both inputs. Anyway, it's much better than the Native, which had an input compressor that forced me to use an additional 20 dB pad.
I have to say, since the nominal max level is now -6 dBu, the gain pot is quite fiddly to set since it's in its very first degrees of rotation.
, and what appears to be a high signal level output (up to 7.7Vrms).
I'm not sure of the capability of driving low-Z loads at this level. My interface has a booster and a 1646, so I'm not really concerned.
Here's hoping you can work out the glitch at 65kHz !
I believe it's due to REW. Depending on level, time of the day and planet alignment, the glitch changes erratically.
It also looks like it would have reasonable performance down at 2Hz to allow a practical flat line compensation.
This I don't know. I don't do seismic analysis. :)
 
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trobbins

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Yeh I think we all have our own ways of using such an interface, and for a variety of reasons. I don't calibrate the digital levels, so normally keep the input pots at min - the valuable signal information is going to fall somewhere within a 120dB span (y)

That unit has a peak indicator at least - not as good as a group of level LEDs, but better than nothing.

Like the Scarlett, it is USB powered, so that's a win for managing mains earth loops.

I'll often want to see below 10Hz, whether its for tremolo/vibrato LFO, or global feedback assessment, or using the impedance measurement setup, and although REW only normally goes down to 2Hz, John gave me a version that goes to 0.1Hz when I had an issue - but my soundcard gets ratty at lower frequencies below about 2Hz.

I concur about the planets aligning ! I've sometimes repeated a measurement scan 5-10 times to get one clean enough to store away. I presume your using ASIO driver. From what I can glean from John's comments on his forum, it likely comes down to the host PC not getting interrupted by other processes and dropping a reading sample or two. I have a laptop for when I want to avoid hum loops, and it has a minimal number of active processes - I should try and cross check performance when I'm having a hard time getting a good measurement next time on my main PC.
 

Whoops

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That Tascam seems like a nice soundcard.

A question to Abbey and Trobbins,
In general terms and on average how high do you need to go on the freq response measurement?

do you have a lot situations where you need to know what’s going on above 50khz?

thank you so much
 
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scott2000

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. I presume your using ASIO driver. From what I can glean from John's comments on his forum, it likely comes down to the host PC not getting interrupted by other processes
Does adjusting the computer system properties to allow the processor scheduling to allow for best performance of programs vs background services help with this? I know Windows has this option and I'm guessing since it's carried over from using drivers for audio it may, and has already been discussed ?
 

abbey road d enfer

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Anytime you want to test a xfmr, particularly line input and output types. The only ones you don't need above 50k are the high-Z mic input types.
Also many power amps have a very high -3dB point.
For a 1st-order (one dominant pole) circuit, for achieveing -0.1dB at 20kHz, the -3dB BW must be 130kHz.
 

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