Warpspeed -An Optocoupler Volume Control

[Blues]

The Warpspeed came about to address some of the shortcomings of current LDR volume controls. On the list are:

-the inability to adjust to complete silence
-on low/high volume level settings, power levels on the LEDs endanger/shorten/toast the life out of the optocouplers
-the need to improve the power delivery to the optocouplers
-the need to improve on quality of the volume adjustment pot
-the Lightspeed, simple as it is, still has a number of variables/design factors that affect performance

The Warpspeed solves the above and then some. Added bonus are:

-low volume levels are more engaging and equally enjoyable (ie. the music details are as much as when at moderate/loud levels)
-low volume listening is perfect in conjunction with NP's monotonic amps -decreasing distortion at lower audio levels (might explain above experience)
-wider range of volume level settings
-battery power means less ac power related artefacts on optocouplers
-precise power delivery and control at safe levels on optocouplers
-by design keeps optocouplers' power level ratio at/near equilibrium
-peace of mind at any volume level

Forgive me for what may sound like a controversial choice of name...some of Star Trek's storylines are still controversial and significant to this day.

More to come soon...

[Blues]

Initial discussion started here http://www.diyaudio.com/forums/analo...ml#post2357974 and in some of the other LDR related threads...

[Blues]

For your weekend reading pleasure, hopefully. The theme is my amateur attempt not to bore readers... I also felt some members thought this was fiction

[CharlieLaub]

Dark matter/antimatter???

How about posting a plot of distortion versus attenuation at 1V signal level. That should get to the heart of the dark matter in your new LDR attenuator.

Here is a link to a post on this forum from Nelson pass, on the distortion of the popular lightspeed attenuator at 1V:
http://www.diyaudio.com/forums/analo...ml#post1520950

So far, I am not impressed.

-Charlie

[Blues]

So far, I am assuming, you have not built one (any variant is easy enough) and given it a listen...maybe numbers don't tell the whole story? I also see you're not a Star Trek fan?

[CharlieLaub]

No, haven't built one, and don't plan on it.

I don't really see the advantage of building a volume control that adds distortion, sometimes a lot of it. All the so called "advantages" of the LDR based attenuators, like no contact noise, having an "off" position, etc. don't make up for that deficiency in my opinion.

So, if your warpspeed bridge design can address the distortion issue, that would be a huge advance for these sorts of controls. Please consider measuring and posting info on distortion so that a fair comparison can be made.

-Charlie

[Blues]

If you get a chance please do build one. I'm speaking for myself here, but I know there are others out there and I was a doubting Thomas too until I decided it's too simple to pass on building it. It is ridiculously amazing the way the music ebbs and flows! Distortion is really that good? I haven't come across anyone who have tried and not like it soundwise.

Once you have one built, and it doesn't have to be a Warpspeed, then listen. Let us know if you are able to tell the x amount of distortion there. Then please measure...

Down the road will do...

[Blues]

I usually evaluate a new component inserted in my system, which I have for the past 6 years -speakers at 10, by listening to familiar music. Physical and emotional responses I take mental notes on can be -tight, clenched jaw/teeth or relaxed with eyes closed; ear fatigue or not after half-hour of listening at moderate to loud levels; tapping of feet/hands/fingers and even getting up to bust some moves; tightness/rhythm of bass lines and sparkle of highs compared to past listening; addition of microdynamics never heard before; soundstage definition at listening sweet spot and to about 2ft from and center of stereo speakers; low level listening and noting difference; ability for long-term listening and enjoyment; moving about within the house and listening; watching a movie with the system and noting slam-bang abilities, and dialogue -usually a system that performs well with music does well with movie soundtracks too.

I'm happy to say, for almost a month now, the Warpspeed does all the positives with the added bonus of low power battery and zero noise operation; zero turn-on thumps with bi-amps powered on; and true volume control capabilities. I'm tempted to conclude CD sound was given a bum rap after all these years...after my pre-amp was taken out of the signal chain, listening has become a lot more easy-going with a lot more music/lyric clarity and definition...

[maxw]

Originally Posted by Blues

-on low/high volume level settings, power levels on the LEDs endanger/shorten/toast the life out of the optocouplers

Can you elaborate on this? Why is this so when the devices tolerances are adhered to? Just curious....

Also, why don't you mention the input/output impedance issues too? ie source impedance has to been less than 100Ω, amp impedance more 50kΩ etc.

[Blues]

Originally Posted by maxw

Can you elaborate on this? Why is this so when the devices tolerances are adhered to? Just curious.....

This issue is with the Lightspeed and some of the other variants that followed. Not the case with the Warpspeed.

[/QUOTE]Also, why don't you mention the input/output impedance issues too? ie source impedance has to been less than 100Ω, amp impedance more 50kΩ etc.[/QUOTE]

I have tried a couple of Toshiba CD/DVD players with a quoted output impedance of 200Ω and 220Ω (2Vrms max); and two Sony - one an SACD/CD and another Blu-ray/DVD/CD, both at 10k (2Vrms max) on the specs. It did not make a difference in performance ie. listening levels were still from 9:00 thru 3:00.