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Well-known member
Aug 19, 2006
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. EQ ONE and MICPRE ONE (launched in the Pre-Amplifiers forum).

The kits are ordered through either WHITE MARKET or directly from www.totalaudiocontrol.com


EQ ONE is one of the first in our flagship “Designed by Langley” series of pro-audio products. Yes, what is going through your mind is correct. It is indeed designed by the man himself.
The "real"stuff.

EQ ONE follows the topology of the four band parametric equaliser that Graham first used in the Amek M3000 mixing console in 1979. This was later adapted for use in M1000 and M2500 consoles and formed the basis of the equaliser design in many other Amek and Total Audio Concepts consoles.

As with the original design, 12dB/octave swept high and low pass filters are included. The frequency bands have been revised to be more suitable for a stand-alone equaliser and noise performance has been improved.

The topology differs from many other state variable filter designs in that each band is composed of a 6dB/octave high pass and a 6dB/octave low pass filters with different turnover frequencies. This enables the bandwidth to be varied over a wide range and also facilitates the Bell/Shelf switching on the High and Low frequency ranges. The Q control is disabled when in Shelf mode.

The parametric section and the filters section may be individually inserted in the signal path.

A single LED provides indication of signal level. This has quasi-PPM ballistics and illuminates green for signal present (-18dBu), yellow for signals above +4dBu and red for signals above +18dBu.

Typical specification:

High pass filter: 20Hz to 400Hz @ 12dB/octave.
Low pass filter: 800Hz to 20kHz @ 12dB/octave.
High frequency: 660Hz to 20kHz, +/-15dB, Q: 0.25 to 1.5 with shelf mode.
High mid frequency: 320Hz to 10kHz, +/-15dB, Q: 0.5 to 3.2.
Low mid frequency:               100Hz to 3.2kHz, +/-15dB, Q: 0.5 to 3.2.
Low frequency: 32Hz to 1kHz, +/-15dB, Q: 0.25 to 1.5 with shelf mode.

Frequency response (EQ out):               +/- 0.5dB, 20Hz-80kHz.
Phase response (EQ out):                      +/-20 degrees, 20Hz-80kHz.
Maximum input and output (100k load): +27dBu.
Internal operating level/headroom:        -6dBu/+27dBu.
THD&N (EQ in or out, +10dBu input signal):better than 0.05%, 20Hz-80kHz.
Noise (no EQ in), 22Hz-22kHz, RMS, 40 ohm source:  -103dBu.
Noise (typical EQ setup), 22Hz-22kHz, RMS, 40 ohm source: -90dBu.
Input/output impedance: 20k ohms/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.


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

As you can see  the module is a double width type. There are many reasons to it. Firstly, there is quite a lot going on. Keeping it to a single width would require the use of dual concentric potentiometers and result in extremely densely populated and diy unfriendly boards.  But the main reason is to allow user modifications to be made, particularly with the use of input/output transformers.

The input and output stages are kept on a seperate card to allow modifications to be made to these stages to suit your own inividual taste. (For this a proto board is provided as a seperate accesory.)  However, please note that the above specifications  will not be valid after any modification.

Here are some images.








The IN/OUT Interface Card is removed.


The proto board in place.



Main EQ Card.


Potentiometer/Switch Sub assemblies.


IN/OUT Interface Card.
Thank you all for your comments.


It is now on sale in the White Market.

Hello Cemal,

may I ask if both the +/-16 and +/-24vdc rails are used in this build?
From your assembly manual (initial voltages,page 25) I can see that only the lower voltages are mentioned.Meaning for non-51x-builders,must the lower two pins on the card edge be cut off?
Just curious..... ;)

Thank you in advance,

best regards from munich,germany,

Hi Udo,

You are most welcome.

There is no need to trim the lower two fingers.

The module operates with + - 16V rails as usual.

The + -24V rails are also available on the boxed header for the user modification on the I/O stages. 

Kind regards,

Thank you Cemal,

that makes sense indeed.
Personally I have 51x racks anyway,so I have sent you a mail asking for a quote  :)).
Good idea to have a block diagram right at the start of the manual btw!
Will there be schematics or pinouts for the headers?


Hi Udo,

I have received your e-mail.

For the info, the sechematic and the pin outs will be supplied with the kits.

Kind regards,

Hello Cemal,

that's great to hear,thank you very much!
Will wait for your quote...and hopefully get started building them soon :D

Have a nice weekend,

Hey Cemal,

Nice work with Total Audio Control products - looks and I'll bet sounds - top shelf!

Off topic some, but I wonder and look forward to a dymanics module to accompany the Pre and EQ modules.

Can only magine what it would (will) be like  :)

Best regards
Hi Alex,

Many thanks.

We have a list of designs in our program and dynamic control is indeed one of them. Three more modules are under test at the  moment. They will hopefully be available by mid autumn.

Kind regards.


EQ ONE is now also available in Black.

The web site with online purchasing facility is also open.




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