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Audible Illusions Modulus

olds1959special

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I just pulled the trigger on this. I was looking for a more tubey sound. I plan to use my DAC remote to lower volume. I'm not sure if this is the early original version or the later Modulus II, etc. Any advice or opinions? Thanks.
 
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Friend had one of those. Note it has a very high output impedance. I think it was 1200 ohms. So keep interconnect between preamp and amp short. It also seemed picky about tubes being microphonic. So use good tubes.
 
Friend had one of those. Note it has a very high output impedance. I think it was 1200 ohms. So keep interconnect between preamp and amp short. It also seemed picky about tubes being microphonic. So use good tubes.
I have to use 6 foot cables to my amps. I hope that's not too long.
 

I just pulled the trigger on this. I was looking for a more tubey sound. I plan to use my DAC remote to lower volume. I'm not sure if this is the early original version or the later Modulus II, etc. Any advice or opinions? Thanks.

Ah - they are not tuby sounding at all.
Just pretty low distortion for a tube pre, and not grainy, and not really anything at all but good.

My Modulus is inverting, so if you look at the photo in the avatar, then you will see the back and red wires reversed.
That mix up at the speaker is not a mistake.

Friend had one of those. Note it has a very high output impedance. I think it was 1200 ohms. So keep interconnect between preamp and amp short.
1200 ohms is not really high, unless the amp’s input impedance is really really low.

I have run 15’ ICs to amps, or maybe 20’…

Just get an IC which does not have a high capacitance and it will be fine.
Like anything Mogami, Beldon, etc.


It also seemed picky about tubes being microphonic. So use good tubes.
I had mine off to the side, in a rack, and just ran it on the OWM tubes for 1/2 century. I’ll probably shove some new tubes in. But i never noticed any microphonic stuff.

I have to use 6 foot cables to my amps. I hope that's not too long.
No - unless they are really weird cables, and the amps are really low input impedance.
But I did not see any Fosi specs… You should be fine.
 
Those AI preamps have a lot of gain in the line amp section. (Too much gain, in my opinion.)
I hope that works for you.
 
So I need to flip the red and black wires on my amps?
 
Those AI preamps have a lot of gain in the line amp section. (Too much gain, in my opinion.)
I hope that works for you.
I guess that could mean more tube saturation. I’ll have to adjust the volume accordingly.
 
So I need to flip the red and black wires on my amps?
I suppose… I always do it at the speaker terminals, but either way would work.

I guess that could mean more tube saturation. I’ll have to adjust the volume accordingly.
I usually have the volume somewhere around 1/2 way, so maybe @Sylvanus means that the if the DAC is outputting high, then you could have a problem??

At least some DACS can have a low or high output, but the RCA should be lower voltage than a XLR… ?
 
It's 30db gain in the line-amp section.
Depending upon your DAC output, power amplifier gain, and speaker efficiency, this can result in horrible, hair-trigger operation of the volume controls in many cases.
 
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I owned version II for several years.
Definitely tube sound - Not in a way you might imagine. Huge tube generated soundstage, so not accurate, but very quiet and a natural subjective impression!

Send it to Amir for measurements!
 
So I need to flip the red and black wires on my amps?
There is no standard so chances are 50/50 that you would be doing the "wrong" thing. Some recordings have opposite polarities on different mics. Fortunately, for virtually everyone "absolute polarity" is not something we've been trained to hear. Do it either way, or do it the way that "sounds" best to you.

P.S. Just to keep us on our toes, some power amps also invert phase.
 
I guess that could mean more tube saturation. I’ll have to adjust the volume accordingly.

I owned version II for several years.
Definitely tube sound - Not in a way you might imagine. Huge tube generated soundstage, so not accurate, but very quiet and a natural subjective impression!

Send it to Amir for measurements!
Why send it?
Measurements date back to the last millennium ,
 
I'm trying to figure out if I got a revision A, B, C, or D (still waiting to receive the unit.) I've noticed the later D ones tend to have a serial starting with M2 and seem to have lettering on the top cover. The serial of mine is M7121667 and I found a 2C online that is M7121687, so only 20 units apart. Yet I found an M7021271 that is a 2B. So I'm guessing the one I'm getting is a 2B or 2C!
 
Some have said to turn it off with a power strip to save the tubes, since they are always powered on. Others have said this is part of the design and is intended that way to save tube life. Which is the correct answer? Turn off with a power strip, or not, to save tube life?
 
Some have said to turn it off with a power strip to save the tubes, since they are always powered on. Others have said this is part of the design and is intended that way to save tube life. Which is the correct answer? Turn off with a power strip, or not, to save tube life?
Been too long for me to remember. Would they have just the heaters on? Some gear has done that to extend tube life. You don't have high electron flow in the tube until high voltage is applied so if they are just keeping heaters on you can leave it on.

Okay, yes they are just powering the heater filaments. Here is a good site of info.


 
It also seemed picky about tubes being microphonic.
Without even looking, I knew that it had to use 6DJ8-family tubes. Looked it up. Yes.

They likely made a common error in the design or construction which any experienced tube guy will immediately know from that description.
 
yeah, mine was microphonic as heck. It was annoying. Ancient history, though (it's in a box downstairs; it is a 2B.
 
yeah, mine was microphonic as heck. It was annoying. Ancient history, though (it's in a box downstairs; it is a 2B.
If you ever pull it out and are feeling ambitious, drop me a note and I'll walk you through how to cure that.
 
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