Does this passive preamp exist?

[Bluedroog]

Hi Guys,

I'm not even sure I'll go the DIY route or not, I've never tried any before so if I were to go this route I'd be limited in terms of ability so would need simple kits.

I'm asking here because A.) DIY to a degree may well be the only way to get what I'm looking for and B.) I trust you guys considerably more than the average hearsayer.

My system is currently SBT - Audiolab M-DAC - Croft 25 valve preamp - Event Opals active monitors.

Now the Croft was a major upgrade in my previous system but I removed it from the chain using the volume on the M-DAC and actually preferred the results. This led me to trying Tisbury and Icon Audio passives and I had positive results which I'd previously not have expected based on prior experience in different systems.

My aim is the swap out the M-DAC for the DDDAC 1794 as I'm after a more natural digital source and a suitable passive.

Given the output of the DDDAC 1794 and the input .755 v/rms is 0dBu of my active speakers is there spec wise a passive you think would be particularly suitable, I'm particularly mindful of not losing any sense of dynamics or 'texture' while benefiting from the transparency of a passive. Basically I want it all without compromise, as much as I can.

So something that spec wise fits the bill
Remote controlled volume I'd ideally like
Balanced XLR a bonus but not essential
Nothing outrageously expensive
Sound quality is very important, I'd compromise a touch for a remote function

I really like the idea of the Lightspeed, not sure this has remote though. The Eva 2 perhaps but I really want reassurance on spec and dynamics.

Many thanks.

 

[JMFahey]

Not sure how can you call "passive" something filled with electronics, including the remote controlleed volume control.
Unless you drive a conventional potentiometer shaft with strings and pulleys pushed by a model airplane servo motor or an equivalent setup.

 

[russc]

Well, to the audio signal a motorised pot is passive.
I guess that's an equivalent set-up?

 

[Bluedroog]

I'm not overly fussed about the name! It may need a power source for features and that is fine with me, so long as it doesn't create adverse side effects such as noise in the signal, as I said I'll accept a degree of compromise in the sound if it means accommodating my required features, but sound quality is my primary concern.


I forgot to mention I only require a single input since I can use my DAC to toggle source and don't have much need beyond, not that I'd mind, mind...

I'd really appreciate input on an appropriate passive pre between DDDAC 1794 and my speakers given the spec in order not to lose any sense of drive.

Many thanks.

 

[Bluedroog]

Well, to the audio signal a motorised pot is passive.
I guess that's an equivalent set-up?

I'm not even sure if what I'm asking contradicts its self in anyway, I probably should've been a bit more explicit in articulating my level of technical understanding!

I'm trying to read up on the various merits and pits falls of volume implementation, I really like the idea of LDR but have never experienced it, I'd like something which outperforms the Icon, although I thought that was pretty good in my limited experience of pre-amps in my current system.

 

[AndrewT]

Use a log law (audio taper) dual track potentiometer.

Then compare all others to your "basic standard".
If some are better then you are pleased, if some are worse you bin them.

 

[DF96]

All volume controls add noise. Some (such as LDR) add a little distortion too. Almost all competently-designed volume controls add so little of each that they are aurally transparent.

Follow AndrewT's advice. Put a decent quality pot in a box, with an input and an output. Job done. If you need remote control then add that in whatever way you like.

 

[Speedskater]

Doesn't the M-DAC have a volume control? If so all that is needed is a stage gain attenuater pad. Something that adjusts the M-DAC full output to as loud as you ever want to play.

 

[Bluedroog]

Doesn't the M-DAC have a volume control? If so all that is needed is a stage gain attenuater pad. Something that adjusts the M-DAC full output to as loud as you ever want to play.

Yes it does, feature wise it is spot on, exactly fits my needs but I want to upgrade to a better DAC and have my eye on introducing a DDDAC 1794. I also tried a passive with the M-DAC attenuation disabled and it was an improvement in audio terms.

 

[Bluedroog]

Use a log law (audio taper) dual track potentiometer.

Then compare all others to your "basic standard".
If some are better then you are pleased, if some are worse you bin them.

Thanks, and for seconding DF96. I'll have to research to make sense of this as simple as it most likley is in DIY audio terms. Sets me on the right path though and will no doubt raise questions I've not yet considered, which is a good thing.

Would you mind giving me your thoughts regarding impendance in my situation? I've read various bits depending on volume implementation where most highlight how vital it is to match (which is my experience, more through trial and error) while others claim their chosen tech makes it a non issue, I can't help think it may be marketing in those cases.

 

[DF96]

The value for a volume pot should be somewhere in the region of sqrt(Rs x RL) where Rs is the output impedance of the source and RL is the input impedance of the load (e.g. power amplifier).