3D imaging pre-amp

This looks like a fun little project!  Is this totally a passive device (no power needed?)  What is the insertion loss on this?  I have too much gain in my system, so it looks like this might help with that problem too  8)  Is anybody using this in their main system?  I'm guessing this would go between the preamp and amp?  Thanks,

Dave
 
aragorn723 said:
Is this totally a passive device (no power needed?)

yes, no power needed!
aragorn723 said:
What is the insertion loss on this?

I don't know, but I think it's a bit high, better have a preamp with my cmoy headphone amp (which is quite strange given cmoy driving capability!)
aragorn723 said:
I'm guessing this would go between the preamp and amp?

Yes, better!

Ciao!
 
The only controls are a pot to adjust crossfeed effect to taste (purple one) and a switch to disable the circuit; the other pots and controls are for the BSC filter for luodspeakers use only.

I must sa the build is really straightforward, thanks to the excellent instruction published by rlyach.

Ciao!
 
What do the two items circled in red mean?

Thanks, Dave
 

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The point where the musical signal (conventionally a sine wave) get in and out the circuit.
You can substitute it with RCA jack symbol!

Ciao!
 
I'm shuffling through my parts boxes.  I'm thinking that if I don't have a 1nF I might just keep the same RC product and use a different value.  It looks like one of my RS 100k Audio taper pots will do well, great value for $3.

I have a torn plantar fascia so I need to play with something while healing.

Oh, thanks for the pictures I have some of that perfboard or what ever it is called.
 
rlyach said:
Thanks Paul, Now I know why I was confused. I assumed that since low frequencies are omnidirectional that delaying the high frequencies is more important. With your explanation on the psychoacoustics of the stereo image, the circuit makes perfect sense. So when they say that bass is omnidirectional, does it mean that the brain does not use loudness to locate the sound like it does with higher frequencies? It is rather convenient that delayed low frequencies make this work. Hence you can use the simple RC low pass filter.

There is a common misconception in audio circles that goes along with the phrase "bass is omnidirectional." What does that phrase really mean?

If you take it to mean, "most speakers approach omnidirectional radiation as you go lower in frequency" that's entirely correct.

But a lot of people have, without thinking it through carefully, translated it to mean, "we can't hear what direction low frequency sounds are coming from." This is not correct at all. You often see this assumption come up in discussions of single subwoofers, or the point one channel in 5.1 surround systems.

Think for a moment of hearing the sound of an airplane from a large distance. This is an example of low frequency sound without a high frequency component. The transmission loss in air has erased all high and even mid frequencies, leaving nothing but the lows. We have no difficulty locating the source of the sound.

In fact the common experience of hearing the sound emanate from a different point than the point where our eyes place the airplane is a further illustration of just how strongly we are able to localize the origination point of the sound.

It's also true that low frequency sound wraps around objects in its path, like our heads, in a different way than high frequency sound. This has many ramifications for us, but I don't think "omnidirectional" is the right word to describe this effect.

Just trying to bring some clarity.
 
Bonzo,
Please post your impressions. I don't use headphones much with my SEX amp, but if this has good affect on near too field I just might build one.
Jess
 
Bonzo,

Yes, please do  ;D  What are the Russian PIO caps called/who sells them?  I'm looking for the parts to build this thing now, that 1 nf cap = .001 uf, right?  Thanks!

Dave
 
thanks..  just one more question, how critical are the voltage/wattage/tolerance ratings on the components?  I have some Vishay Dale 1/8 watt 100k resistors already, but might need some help figuring out what voltage/wattage/tolerances to buy. 

Dave
 
@aragorn723
I bought caps on fleabay, searching for "___uF matched" (fill the correct value). The search will return you almost only russian PIO caps. Please take note that russian 1nf caps have big lead legs, you'll need to enlarge pcb holes and trim a bit the legs to accomodate them. I don't know about resistors, I used 1/4w but I think 1/8 will be ok too

@jake111
I'll try with a simple setup: quickie, t-amp and fostex fe103 on my desk. Test disc "Misterioso"...  8). Will report later.
 
aragorn723 said:
might need some help figuring out what voltage/wattage/tolerances to buy. 

I forgot to add thath it's better to match components between L and R channels (as usual) and that for capacitors the higher the voltage the better.

But given the small capacitance required, you won't have a lot of voltages to choose from anyway.

Ciao!
 
Ok,
some quick impressions when using in nearfield setup: no quickie, only ipod touch with direct output > 3D preamp > Fenice 2024 amp > Fostex fe103.
The first thing I noticed was the apparent lack of low frequencies, voices and trumpets were thinner than before, but after a moment the effect of broadening the sounstage was there! And made me forget the harshness

My ears were at 1m from the speakers, so after a while it was very fadiguing to keep on listening anyway.

I wish I had my Yamaha small monitor at home, just to try a more bass friendly speakers.

The "3D effect" added, however, is really interesting!
 
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