The Ensoniq DP/4 is a great sounding 24-bit digital effects processor combining four independent effects processors, and four independent inputs and outputs featuring full mixdown capabilities.
The Avalon Design VT-747sp combines a creative STEREO tube-discrete Class A spectral-opto-compressor with a musical six band program equalizer, L-R output level and gain reduction metering and internal regulated power supplies in a 2U space. Ideal for high performance DAW input signal conditioning, stereo buss compression-EQ, stereo keyboards and analog mastering applications.
The opto-compressor features a minimum signal path design utilizing sealed silver relays for all signal routing and by pass functions. The optical attenuator acts as a passive level controller with a Class A, variable gain make-up amplifier. Full dynamic control from soft compression to hard-knee limiting can be achieved with master threshold, ratio-compression, attack and release controls. Gain reduction indication is a large analog VU meter. Low frequency and high frequency contour parametric spectral controls can be routed into the side-chain path for enhanced frequency dependent compression with variable frequency and threshold levels. SC listen provides side-chain listen mode for monitoring.
Six Band Program Equalizer
The Avalon Design VT-747SP equalizer utilizes 100% discrete, Class A high-voltage transistors for optimum sonic performance. The six band STEREO program EQ incorporates the smooth characteristics of an all passive design. The frequency turnover, Q and amplitude ranges have been carefully chosen for each band to provide the most natural harmonic balance and lowest phase change while offering simple and effective tone control. The EQ can be placed pre or post the opto-compressor for enhanced effects.
TSP – Twin Signal Path
The Avalon Design VT-747SP features TSP which gives you the choice of either tube tone or the classic, Class A discrete transistor sound by exchanging, three (3) high-voltage dual triode tubes with discrete amplifiers in the opto-compressor and primary output stages.
Input-output & Metering
Fully balanced DC coupled, Class A discrete amplifiers are utilized for the input and output drive interface with+36dB input headroom. A high quality analog VU meter indicates accurate gain reduction. Twin 60dB range LED meters provide fast L-R output status of all levels.
I owned the Avalon Design VT-747SP for about three years and loved it. (I have since sold most of my studio gear) The build quality on Avalon gear is just ridiculously good, and the design superb, nothing looks better in my view. The compressor is not really designed for hard core compression like a DBX 160 or the like, it is more of a subtle compressor in that regard.
The EQ section is what most people simply do not get their head around fully. The complaint you will hear over and over, is that the frequency bands are not marked to indicate the frequency each adjuster is affecting, but that is the whole point! It is a VERY musical EQ that is designed to be tweaked by ear (remember those things?) and to me at least gives excellent results.
If you are after older hardware that has some kind of magic mojo because it is not pure in the signal path, this is not for you. Sound coming out of the Avalon Design VT-747sp is almost as pristine as what goes in. It is a shame that after all these years Avalon have decided to stop producing it, I guess they got sick of trying to make people understand it’s design and purpose. If you can get one on the used market do so, it is a magic box in my eyes!
Compressor type: Optical passive attenuator
Make-up gain: Variable 0dB to +10dB stereo tracking
Threshold – Ratio: Threshold variable -30dB to +20dB, ratio-compression variable 1:1 to 20:1
Attack – Release: Attack variable 2mS to 200mS, release variable 100mS to 5 seconds
Side-chain spectral contour: Variable threshold -15dB to +15dB, frequency 70Hz to 9kHz twin ranges
LF +/-24dB 15Hz shelf response
MF1 +/-8dB 125Hz selected Q response
MF2 +/-4dB 500Hz selected Q response
MF3 +/-4dB 2kHz selected Q response
MF4 +/-10dB 5kHz shelf response
HF +/-20dB 32kHz shelf response
Frequency Response: 1Hz-200kHz
Dynamic Range: >92dB
THD: Below 0.5%
Power Consumption: 70 watts
Dimensions: 482 x 305 x 89mm