[iFi audio]

This is may back up plan. I think about add two 100 ohms resistors to 2.5-6.3 adapter.

My sincere advice is to try iEMatch. It will expand headroom for your headphones, but with no drawbacks that come with resistors. iEMatch is more than that

 

[diamondears]

@iFi audio what's the difference between the first iTube's Digital Antidote Plus vs. iTube2's Tube+ switch?

Also, on iTube2, re SET-Classic-PP switch, the differences are the amount of feedback? So SET is least/zero feedback, Classic most feedback, PP less than Classic but more than SET?

Sorry if this has been answered before, thread is too long to scan through

 

[iFi audio]

@iFi audio what's the difference between the first iTube's Digital Antidote Plus vs. iTube2's Tube+ switch?

The Tube+ mode in action is similar, but offers three distinctive sound profiles. PP amps don't sound like SETs after all

Also, on iTube2, re SET-Classic-PP switch, the differences are the amount of feedback? So SET is least/zero feedback, Classic most feedback, PP less than Classic but more than SET?

I'd have to ask and I'm not sure whether we could release info about how the three options provided differ exactly, but amount of feedback in each case is different.

 

[diamondears]

The Tube+ mode in action is similar, but offers three distinctive sound profiles. PP amps don't sound like SETs after all



I'd have to ask and I'm not sure whether we could release info about how the three options provided differ exactly, but amount of feedback in each case is different.

Which of the SET, Classic and PP options most closely resemble the Digital Antidote Plus option in first iTube?

 

[diamondears]

The Tube+ mode in action is similar, but offers three distinctive sound profiles. PP amps don't sound like SETs after all



I'd have to ask and I'm not sure whether we could release info about how the three options provided differ exactly, but amount of feedback in each case is different.

It is precisely what we are doing. In the iTube 2 (and in the Pro line) we adjust the open loop gain to differing amounts.

If you reduce the open loop gain within a feedback circuit, it will also reduce gain slightly.

The ideal feedback circuit has infinite open loop gain. Then overall gain is set absolutely by the amount of feedback.

If by comparison we take a circuit with an open loop gain of 1 (however this may be achieved) and a normal feedback loop applied, the gain is set only by the open loop gain and the feedback loop is in effect defeated.

Using above unity but finite open loop gain gives results in-between the two extreme cases set out above. Changing open loop gain will also affect overall gain and yes, SET has the least open loop gain and so the least closed loop gain. The differences in gain are however quite small even so.

The valve giant just got bigger… - part 3/5

The Harmonic Envelope control adjusts the amount of feedback in the circuit, trading-off transient performance and harmonics generation, allowing the sound signature to be adjusted between a modern tube preamp, a modern push-pull amplifier or a single-ended amplifier.

The difference between ‘classic studio’ and ‘push-pull’ is in the levels of harmonics. These are greater in the latter case (just as they would be in this kind of a tube amp in comparison to a studio preamp) and feature appx. equal amounts of 2nd order harmonics and 3rd order harmonics. There are similar relations between the even/odd harmonics at higher harmonics. For the ‘single-ended’ signature overall, 2nd order harmonics are much higher than these of 3rd order, whereas the other harmonics fall-off in a similar manner with the even order harmonics in each pair significantly higher. This would be the case with a low/non-feedback SE Amplifier.

3D Holographic+ Matrix for Speakers®

Based upon a fundamental understanding of how we hear, stereo separation is different at different frequencies. However, very few recordings and no playback system compensates for this issue. With the introduction of 3D Holographic Matrix® for Speakers, the iTube2 provides the means to specifically and correctly reproduce stereo recordings for both floor-standing speakers and desktop speakers regardless of price even US$100,000 speakers.

Our proprietary XBass+® and 3D Holographic+® enhancements are in fact ASP (Analogue Signal Processing) filters based on Alan Blumlein’s work. There is no DSP, therefore not handled in the digital, but analogue domain. Microphones are not ears, whereas speakers + rooms and/or headphones are not really just microphones in reverse. As early as the 1930's, the inventor of modern stereo recording/playback systems - Alan Dower Blumlein - realised that microphone based stereo audio recordings distorted the 3D perspective in comparison to the real thing listening.

The Blumlein Shuffler




Source: British Patent: 394,325

Alan Blumlein devised a compensator known as shuffler. for the speaker side of things and also did some work at the headphones end. Said compensation technology was implemented later by EMI as ‘Stereosonic’ process and applied to early stereo recordings (including some by The Beatles). The headphone compensator never was completed. At later time, inventors such as Bauer presented their takes.

In the end, both Blumlein/Stereosonic shuffling and the Bauer/Linkwitz/Meier cross-feed systems remain worthwhile. But attempts to correct a fundamental dichotomy or flaw in modern stereo recordings were unsuccessful. What the iFi 3D-Matrix has to offer is an improvement over the previous corrective systems and we feel we have achieved this. And while there are of course parallels, which overlap with classic Blumlein shuffling and Bauer crossfeed, the iFi 3D-Matrix goes well beyond. The iDSD micro was actually iFi's first product to contain 3D-Marix ready for both speakers and headphones. Only our Retro and iCAN Pro models share this technology, whereas 3D-Matrix headphones side was introduced in iCAN and its speakers side was to be found in iTube and now in iTube2 as well.

The whole line-out processing implements a Head Related Transfer Function (HRTF from here-on) that is designed to correct standard microphone recordings played back on speakers.

XBass+ Matrix®

Many speakers show limitations and deficiencies in low frequency response. With the introduction of XBass Correction® for speakers, the iTube2 provides the means to specifically bypass these limitations and correctly reproduce low bass frequencies through a wide range of speakers.



More to come!

The Tube+ mode in action is similar, but offers three distinctive sound profiles. PP amps don't sound like SETs after all



I'd have to ask and I'm not sure whether we could release info about how the three options provided differ exactly, but amount of feedback in each case is different.

Saw these. So SET is zero/least feedback, PP has more, and Classic has most? Which of these is exactly that of when Digital Antidote Plus is ON on the first iTube? Reason I ask is I seem to like the first iTube with Digital Antidote Plus ON. Or I just need to break-in the iTube2?

 

[iFi audio]

Saw these. So SET is zero/least feedback, PP has more, and Classic has most? Which of these is exactly that of when Digital Antidote Plus is ON on the first iTube? Reason I ask is I seem to like the first iTube with Digital Antidote Plus ON. Or I just need to break-in the iTube2?

Let me ask about this internally, and once one of our engineers gets back to me, I'll let you know, alright?

 

[diamondears]

Let me ask about this internally, and once one of our engineers gets back to me, I'll let you know, alright?

 

[iFi audio]

OK, to make it short, there's no setting in iTube2 that would resemble what Digital Antidote did in the original iTube.

 

[diamondears]

OK, to make it short, there's no setting in iTube2 that would resemble what Digital Antidote did in the original iTube.

Ok, thanks. Might scamper for an original iTube now as it’s sound is slightly different, like having a different amp. iTube2 is more resolving and transparent, but I hear a slightly different sound character. Due to the different (although same brand and type) tube probably?

 

[diamondears]

And in that connection, is it possible to tube roll with the iTube and iTube2?

 

[alekc]

And in that connection, is it possible to tube roll with the iTube and iTube2?

No point in doing it since both revision of iTube are based on the same GE tube: 5670. Tube rolling will also void your warranty I guess.

 

[diamondears]

No point in doing it since both revision of iTube are based on the same GE tube: 5670. Tube rolling will also void your warranty I guess.

Thinking of other brands of 5670, or even 6922. Can this be done? Is the GE 5670 tube inside the iTube/iTube2 just plugged (hence removable) or soldered?

 

[Jon L]

Thinking of other brands of 5670, or even 6922. Can this be done? Is the GE 5670 tube inside the iTube/iTube2 just plugged (hence removable) or soldered?

Tube rolling iTube will void warranty, and there is very little room inside due to that black connector at tube tip, so that tubes taller than 5670/2C51 such as 6385/6n3p will not fit. I do wish iFi would move that black connector up a few milimeters.

iTube2.5 by drjlo2, on Flickr

 

[iFi audio]

Due to the different (although same brand and type) tube probably?

The same cherry-picked JAN GE5670 in both.

Thinking of other brands of 5670, or even 6922. Can this be done? Is the GE 5670 tube inside the iTube/iTube2 just plugged (hence removable) or soldered?

As @Jon L nicely showcased, tubes can be removed. WE396A would be what I'd consider an upgrade over GE5670.

 

[diamondears]

The same cherry-picked JAN GE5670 in both.



As @Jon L nicely showcased, tubes can be removed. WE396A would be what I'd consider an upgrade over GE5670.

Thanks