MICPRE ONE -by Total Audio Control / NOW ALSO AVAILABLE IN BLACK

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sahib

Well-known member
Joined
Aug 19, 2006
Messages
3,845
Location
Glasgow - UK
As a result of my collaboration with Mr Graham Langley I am throwing my hat on the ring with two new kits under Total Audio Control brand. MICPRE ONE and EQ ONE (launched in the Equalisers forum).

The kits can be ordered either through the WHITE MARKET or directly from the web site www.totalaudiocontrol.com

MICPRE ONE

MICPRE ONE is one of the first in our flagship “Designed by Langley” series of pro-audio products. Yes, it is indeed designed by the man himself. The "real"stuff.

MICPRE ONE is similar in topology to the transformerless design Graham used on the Amek M2500 mixing console and the original Angela console of 1982.

A number of improvements have been made, but the design retains the use of parallel matched transistors and constant current sources. Exceptional noise performance has been achieved. Particularly at low gain settings. The signal path is balanced throughout.

0dB to 66dB of gain is selected in 6dB steps by a rotary switch and this is followed by the fader stage which provides an additional 4dB of gain and up to 24dB of control to adjust between switch settings and also to attenuate the final output to suit consumer interface.

Switches are fitted for input impedance selection, a passive high pass filter before the preamplifier, phase and phantom power.

A high impedance balanced instrument input is also provided on a front panel jack.

An additional switch selects the source for a second front panel that can provide a balanced “THRU” output directly from the instrument source, or monitor off the main path.

When the MON switch is OFF the THRU output at the front is connected to the INSTRUMENT channel and gives a balanced intsrument output. In this mode the microphone and instrument inputs are used at the same time. While the microphone input makes use of the full gain stage, the instrument in/out is at unity gain. In other words the instrument channel acts as a buffer.

However, when the MON switch is ON the THRU output connects to the microphone channel and gives a split output at the same level as the main output. In this mode the instrument input is disabled.

When the INST switch is ON the microphone input is disabled and instrument input makes use of the full gain stage and the THRU output again provides a split output at the same level as the main output.

An 8 segment pre fader LED meter is provided. The Signal Present LED illuminates at -18dBu. The response of the main bar approximates that of a PPM, while the +18 LED has faster attack and slower decay to catch peaks.

Typical specification, both paths:

Mic. input impedance:         switchable 5k ohms/600 ohms
Instrument input impedance:         switchable 1.5M ohms/50k or 10k ohms
High pass filter:         120Hz @ 6dB/octave (nominal).
Frequency response:         +/- 0.5dB, 20Hz-80kHz (up to 60dB gain).
Phase response (EQ out):         +/-30 deg., 20Hz-80kHz (up to 60dBgain).
Maximum output (into 100k ohms): +27dBu
THD&N (+10dBu input signal):        better than 0.05%, 20Hz-20kHz (up to 60dBgain).
Mic. EIN, 22Hz-22kHz, RMS, 150 ohm source: -128dBu.
Output impedance (main and THRU):              75 ohms



The Kit

The kit comes complete with all the components and a comprehensive assembly manual with detailed photographic illustration of each assembly sequence.

http://www.totalaudiocontrol.com/docs/MICPRE-ONE-ASSEMBLY-MANUAL_26DEC13-LTl0Qp.pdf

However, as well as having a support thread here, there will also be unlimited e-mail support.

Here are some images.

MICPRE_ONE_1_lowres.jpg

MICPRE_ONE_2_lowres.jpg


MICPREONE_01.jpg

MICPREONE_02.JPG

MICPREONE_03.jpg

MICPREONE_04.JPG

Mic Amplifier Card.

MICPREONE_05.jpg

Instrument Input and Meter Card
 
Yes,

I am only doing my best.  ;D

It is now on sale in the White Market.

http://www.groupdiy.com/index.php?topic=52462.0
 
mmm. nice. just finished my MicpreOne. all the tests confirm this baby is fit, healthy and kicking! though there's one small cosmetic/convenience issue....the gain knob when turned fully anti-clockwise (counter-clockwise to some of you ;D) should sit at 0 but is in fact midway between 54 and 66. am i right in thinking i need to remove the rear plate of the gain pot and move the pins or something?

thanks for any tips  ;)
Ian

PS i bottled out of making the CMMR/symmetry tweaks due to owning an under spec voltmeter, anyone of you go through with this? can you notice a difference?
 
Hi Ian,

Weldone.

All you have to do is to loosen the grub screw and re-align the knob. It should sit on 66.

I am in the process of preparing some pictorial documentation on CMRR and SYMMETRY and I will post here on the forum. But most importantly we have designed an active test jig to carry out CMRR and SYMMETRY trimming using the free version of TRUERTA. I am ordering the PCBs this week which will hopefully be ready in two weeks. The jig can also be used with old school Signal Generator / AC-Audio Milivoltmeter set up.

However, it would obviously be the icing on the cake if the CMRR was trimmed using the variable capacitor network but if you use the two 22pF caps supplied on both legs then you will be rocking. The caps are 5% and from the same batch so they will be reasonably well matched and you will not hear any difference. Even if you trimmed it perfectly on your bench it can still be swamped by the cable capacitance in use.

 
thanks Sahib

i don't know why this didn't occur to me. i just saw that flat side and assumed that must be to stop the knob slipping  ::)

i plan on building another one of these this year so i have a pair, and then i'll do the trimming on both....lookin forward to learning more about this process.  :)

cheers, Ian
 
Hi all,


Ii wrote a little review from my latest experience here:


http://groupdiy.com/index.php?topic=52462.msg730371#msg730371


Best,


Udo.
 
Now also available in Black.

The web site with on line purchasing facility is also open.

www.totalaudiocontrol.com

MICPRE_ONE_1_lowres.jpg

MICPRE_ONE_2_lowres.jpg
 
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