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Confessions of a mostly digital active XO stereo junky

DWPress

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Recently I've changed a few things up in my system but two things have stood out as profoundly interesting and contrary to my objective approach toward audio and the signal chain.

I scored some MSB gear on a great deal: 2 P1000 power supplies, a ADD-1 which is a 24/96 ADC and particularly a MVC-1 which is an 8 channel analog volume control.

My primary interest was the MVC-1 because I use a miniDSP 4x10 for paraEQ and XO on a 3.2 system and I had read Siegfried Linkwitz used one with several of his speaker projects. I know it has more or less been proven that digital attenuation at even CD resolution with modern devices should have no affect on the signal and even Siegfried ultimately abandoned it in favor of DSP but my thinking has always been avoiding it as much as possible even to the point of figuring the sensitivity of individual drivers into adjusted output voltages at amps. Prior to acquiring the MVC I was going direct from my computer>usb DAC>spdif miniDSP>gain controlled amps and using the digital volume control. The MVC sounds subjectively better at lower volumes and inexplicably I gained about 4dB of headroom. I think that this actually has more to do with the limitations of the processing power and hardware of the miniDSP though and have been considering a Linux based dedicated box to take over its duties which would also give me FIR filter capabilities and much more processing power.

The ADD-1 is interesting too. Six analog inputs and 24/96 digital out via spdif, toslink or AES which I use now to bypass the miniDSP's poor implementation of ADC.

While I was rearranging everything for all this new gear I found an unused ABX switch and glanced over at my cute little unused tube buffer preamp I built years ago. It takes any variation of 12A*7 pairs and lets you dial in their gain and volume, a simple 12V DC point to point build but relatively silent. I decided to add it into the midrange speaker chain between the DSP and amp using the switch. I've got at least a dozen sets of tubes, some pretty exotic.

WOW, just wow. Objectively I know that those tubes are adding noise into the signal, not improving it. I know that by twiddling those pots I am actually totally messing up my XO structure as well. But, once again, subjectively it just sounds damn good, especially with recordings with lots of "air" like jazz trios, female vocals, solo instruments, etc...

I know that at a flip of a switch I'm back to microphone measured, carefully calculated and calibrated digital bliss. The switch makes it interesting indeed as I can gain match with an SPL meter, swap tubes and geek out. Basically I'm jumping back 20 years and have a crude tone control eh?

Anyone else do crazy stuff like this and double think your think?
 
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