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iTube, Euphonia and Confused Thinking

Jake's Dad

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Hi, All. I'm a new member here just crawling out of the primordial ooze of mainstream subjectivist magic thinking. I was wondering if anyone has ever heard or used the iFi iTube or its successor iTube2. Is this unit (a) a useful tool to tweak sound to one's admittedly subjective, but no less real, preferences, (b) an insult to what might otherwise be a reasonably faithful audio reproduction chain, or (c) something in between? Your considered thoughts would be most welcome.

Cheers, Alex
 

tomelex

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Hi Alex.

I think you need to be clear on a few things as you emerge from the swamp.

--If you are listening to speakers in a room, moving your head a few inches in any direction could create linear distortion changes (FR) of a db or more in certain areas of hearing range. Thus, the room and speakers interaction are the biggest change to the sound and this changes as you move your head around, decoded, if you don't lock your head in a vice don't think that you will ever tune your system for repeatability. Goes for headphones but only a little bit, with them its where you position the headphone on your ears or in your ears each time. So, that's a big variable right there. Summary, position of your head using speakers and room or the headphone on or in your ears ALWAYS makes a change.

--Changing anything in your system so it sounds better to you is fine, just remember paragraph above...
 

Blumlein 88

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The iTube says it does a few things. One of them is said to be the Taddeo digital anti-dote. Here is what I gather the Taddeo device did.

Here is a close up view of a single maximum pulse. The upper one has had a brickwall filter applied at 20 khz and you see the ringing each side of it. The lower one has not had filtering.
taddeo 1.png


Now I filter both of them and notice I had already offset the two pulses by one sample. Notice how the up and down 'ringing' would mostly cancel out if I combined these.
taddeo 2.png


So here is what they combine to if you do that. Notice the peak is blunted, but the ringing is mostly gone visually.

taddeo 3.png


Now I didn't show it yet, but in that same file I had a 20 hz to 20 khz sweep. The upper one is with two of them offset by one sample and combined. The lower one is how such a sweep looks with flat response. The treble is rolled off and the Digital Anti-dote said it was down -3 db at 15 khz. This is a little more than that, but similar.

taddeo 4.png


If I do the same procedure with square waves they also when offset by one sample and combined cancel out nearly all the "ringing". You would think offsetting a duplicate of a file and combining might sound messed up. In fact, other than the softer treble and a warmer balance you'll not hear anything wrong. It sounds more "analog". I'm of the opinion there was no ringing problem solved here. Just equalization to a similar curve gives a the same sound. There once was a analog version of the Digital anti-dote and it was working in a similar manner. It delayed and changed phase of one copy of the signal and combined with the original signal to achieve a similar result.

The iTube also does a couple other things. And you can use a tube in the signal path. I am pretty sure none of them 'repair' digital sound. The 3D sound by description might be partly a mid-side shuffler circuit first described by Alan Blumlein in a patent in 1933. It may do this a bit differently. But the widening of the stage, and correcting for recordings with an imbalance of lows sounds like the same idea. And they mention Alan Blumlein.

So I have no doubt it would change the sound. You may or may not like it. It would be a step away from pure fidelity which is still okay if you like the result. But they aren't repairing anything. You also could do a few tracks yourself and see what you think of the sound. If you like I could give instructions on what to do using Audacity as a sound editor.
 
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Jake's Dad

Jake's Dad

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@Blumlein 88, thank you so much for the thorough (and graphical!) analysis. That sheds a lot of light I think on what's going on with the iTube. I imagine it has a certain utility as an "on the fly" and somewhat crude compensation for a system (or listener?) suffering from over-emphasized trebles. But otherwise, not so much.

Thanks again,
Alex
 

bunkbail

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I own an iTube2, I still don't know what it does to this day.
 

Blumlein 88

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I own an iTube2, I still don't know what it does to this day.

Do you mean you can't hear it doing anything, or you don't like what it does or it does something and you don't know how?
 

bunkbail

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Do you mean you can't hear it doing anything, or you don't like what it does or it does something and you don't know how?
I can't hear any improvement to my system. I've never owned a tube amp before, so I bought it to experience what a tube amp could sound like but honestly when every time I plugged it into my system (I own several DACs, headamps and headphones), I barely notice any differences at all tube modes (classic, SET, push-pull), except for the 3D mode and bass boost (they have obvious impact).
 

tomelex

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While I dd not research this device you guys are talking about, to obtain a SET sound you must have a final tube power amplifier, an output transformer and speaker combination.
 

dougi

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I just received an iTube V1, to use as an impedance buffer. I will try and do some measurements this weekend. Years late, I know. The first thing though, is that the 0dB gain setting seems to be about 3dB in reality.
 

Katji

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[...] I imagine it has a certain utility as an "on the fly" and somewhat crude compensation for a system (or listener?) suffering from over-emphasized trebles.
Now you mention that... it is caused by speaker distortion, or room acoustics problem. Address the problem, not with a gadget/gizmo thing.
PS: If you're using computer/etc. audio player, you could try adjusting EQ for higher frequencies.
 
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naviivan

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I had the original iTube buffer.
As a pre amp I found it noisier than running it straight from the topping D50 to Ice module 125ASX. It was okay but using the Topping L30 was better. Bit too warm sounding for my taste.
As a buffer between the D50 and Sansui Au-907 I found it soften the dynamics - I Didn't like what it did.

I think if I had a hard sounding system this would be good.
 

dougi

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Well I did some measurements of the iTube using my RME ADI-2 Pro. In 0dB gain buffer mode.

Upshot is it probably won't have much of a sound unless you drive it really hard. Given it's high input impedance it should be good as a buffer. May remove a bit of detail for those with the ear for it.

Frequency response 1.5V RMS in, very flat:
itube fr.jpg


THD(&N) sweeps up to 6V RMS in (0dBFS bottom scale). SNR and THD good around 1-2V. 2nd harmonics dominates at high levels.
itube step 2.jpg


1kHz tone spectrum around 1.5V RMS in (ignore the 3V, gain seems about 0.5dB in 0dB gain mode: I am using RME unbalanced, you lose 6dB on the outputs but none on the inputs so -1dBFS out indicated translates to -7dBFS indicated on the input to the RME. Unweighted noise 92dB referenced to the input. I did vary and I have seen it up to 96dB at 1.5V in to the iTube.

itube 1khz thd.jpg


Multitone around 1.5V peak in, not too bad, 15 bits resolution or so.
itube mtone.jpg


CCIF around 1.5V peak in. Similar to the THD but to be expected after looking at the multitone which is pretty flat:
itube ccif.jpg


If you are wondering if the digital antidote does much, here is impulse and step response without it on (through DA and DA "sharp" filters:
no da plus.jpg


Here it is with the antidote:
da plus.jpg

Note that in normal use you wont get the AD ringing so the effect will be greater. It does reduce ringing a bit.

If I had my time again I would use a AD filter in the RME with little ringing so I could have focussed on the DA. The RME has various choices for both.

Plus it changes the top end frequency response a bit:

antidote fr.jpg
 
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Jim Matthews

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I am not so quick to dismiss any enthusiast in their desire to make music playback more enjoyable. However, I think that the professionals mixing the recording likely have experience beyond mine.

My guiding principles (after decades with vacuum tubes and high sensitivity loudspeakers) are as follows:

Gear should operate without additional air-conditioning, in all Seasons.
I shouldn't need a manual to turn it on, or make an adjustment (sorry, RME).

Fewer boxes are preferable in the playback chain.

Everything should be quiet, absent any music playing.

I should be able to turn off displays.

No special treatments for getting the speaker to sound balanced - room placement and positioning should do the heavy lifting.

The playback should reproduce upright acoustic bass close to what I remember - that covers most of what I can still hear.

It should cost less than my car.
 

Wes

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Hi, All. I'm a new member here just crawling out of the primordial ooze of mainstream subjectivist magic thinking. I was wondering if anyone has ever heard or used the iFi iTube or its successor iTube2. Is this unit (a) a useful tool to tweak sound to one's admittedly subjective, but no less real, preferences, (b) an insult to what might otherwise be a reasonably faithful audio reproduction chain, or (c) something in between? Your considered thoughts would be most welcome.

Cheers, Alex

I don't think I'd pay $400 for that tube buffer.

Why not start a new thread which describes your room (diagrams are great) and lists your equipment with the title "How can I Improve my Sound?"
 
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