TDS passive audiophile: first impressions
Nov 10, 2001 at 3:31 AM Post #16 of 28
Regarding hum and TDS you must be careful not to set unit next to/on power supply/transformer or hum will occur.......this is mentioned in owners manual. I have my TDS on its own shelf of Target rack with Bel Canto Dac 1.1 and it is so quiet you can hear a mouse piss on a cotton ball.

Notice the photo has two sets of "mystery" black boxes, one for each channel, this is the Passive audiophile model. There is a cheaper model with just one set for both channels.
 
Nov 10, 2001 at 3:45 AM Post #17 of 28
I tried several locations for the TDS. I talked with Kurt Neal of Ampman Audio where I bought it and with Art Garcia of TDS several times. I even purchased a balanced version of the TDS but could not get the hum issue resolved. Probably a contributing factor was the additional 3db gain from the HRS unit. However, I really like it more than the TDS, inmy system, so it stayed and the TDS moved to the HeadRoom amplifiers. Either way, both products are good tweaks for a system.
 
Nov 10, 2001 at 6:39 AM Post #21 of 28
Quote:

aren't they just acting as frequency selective step-up transformers?


that's my guess as to what it does too.
 
Nov 10, 2001 at 3:01 PM Post #22 of 28
I would guess that it is almost certainly adding a significant amount of harmonic distortion (or "enhancement," depending on one's point of view
smily_headphones1.gif
) as well.
 
Nov 10, 2001 at 7:22 PM Post #23 of 28
Quote:

just being nitpicky, but the word 'gain' is misleading, especially since it's a passive device.


Tehy do look to be transformers,and transformers DO have the ability to increase gain (as in a moving coil step up transformer).
I have never listened to the device but by descriptions I think there is maybe selective gain and phase shifting going on.
By selective gain what i mean is certain frequencies are boosted while others are not and the pahase shifting would be the increased sense of space.
Just a guess.
 
Nov 10, 2001 at 7:46 PM Post #24 of 28
Quote:

Originally posted by rickcr42
By selective gain what i mean is certain frequencies are boosted while others are not and the pahase shifting would be the increased sense of space.
Just a guess.


Hmmm...I listened to Carver's "sonic holography" a while back. While that used phase shifting to increase image size, it also smeared the image. The TDS has an opposite effect: each instrument seems to occupy a more clearly defined space. Positioning is very tight, and even quiet things going on in the background are easier to track.

I may be able to borrow a frequency analyzer from work. If I can, I'll try and post some frequency response curves with and without the TDS.

Another observation: I tried the TDS both with an ART DI/O and Theta Chroma 396. The TDS actually reduced the differences in system sound when the DACs were changed. In listening with and without bypass, the effects of the TDS were much greater with the Theta unit in place. The Theta has a very dry, analytical sound...the TDS gave it a sense of warmth and body that was completely missing. The ART DI/O started with better sound than the Theta, and maintained it. However, the ART already had a warmer and fuller sound, and the changes produced by the TDS were not as radical.

Strange device, but fascinating to listen to (Thanks DarkAngel, for mentioning this unit!). By far the most interesting device I've run into since the DI/O itself. Bottom line to me is that it works as claimed: it makes music sound more "live". Definitely a worthwhile purchase if you can find one.
 
Nov 10, 2001 at 8:07 PM Post #25 of 28
but i wouldn't say it was gain, because any voltage increase comes at a loss of current. so the total power remains the same, maybe even less due to heat loss and stuff. i just find it strange that a passive device can provide gain.

but according to the tds site, it supposedly accounts for the fletcher munson curves and extends tones in the time domain. so i guess it would step up the top and bottom of the frequency range.

compression can be used to 'sustain' tones. the fletcher-munson curves say that at higher volumes the bass and treble need a smaller boost. so the dynamic range of the bass and treble would be compressed. and that's my guess on how it sustain tones.
 
Nov 10, 2001 at 8:18 PM Post #26 of 28
Reminds me of my wow thing, but that is a cheapie active device. However it seems like a form of spatialization. Using time delays and applying loudness EQ and "gain" is the only thing my Wow Thing does...it has stopped wowwing me ages ago, but than again its a cheap noisy and active device. The WoW Thing actually has an audiphile incarnation in an expensive Japanese SAEC 2000 headphone amp.

Its pretty weird if they can do similar things through a few transformers instead of any DSP's.

I'm still wondering when we'll ever see some Dolby Headphone stuff.

I don't mind having processors in the signal loop...but I do think easy bypassing switches should always be an option. X-feed, Dolby headphone, any other sound enhancer is fine to me as long as its easily switchable.
 
Nov 10, 2001 at 8:24 PM Post #27 of 28
Hey Skippy, although I agree with you in principle, - generally it is still considered gain as the circuits involved are voltage driven and the current is so small as to be not worth worrying about.
 
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