[Kentajalli]

This is about a potential DX amp that has, say, 500W per channel capability. No need for a DAC followed by a power amp in that case, instead plug the DX amp into your speakers.

I assumed you were talking about the post in which I suggested to RW about a possible hypothetical TT3 that would have enough power to drive real speakers (100W or so).
I suggested a digitally controlled class D output section.
RW was against that, and suggested class G or H instead of class D. He did so, because class G and H rivalled class D in efficiency, but sounded good (if combined with a class AB).
Just go back a few posts, you will find his recent posts.

 

[freaknout]

I was referring to WTA2, not WTA1.

It's a guess on my part as to the actual latency, though.


This is about a potential DX amp that has, say, 500W per channel capability. No need for a DAC followed by a power amp in that case, instead plug the DX amp into your speakers.

Just reading your system Jawad and interested if you'd tried other streaming solutions up front and whether they made a significant difference?

I ask because I run a pretty cheap WiiM Mini into my Mojo2 but it sounds excellent.

 

[Reactcore]

How is it able to deliver twice the power into XLR?

Is it a bridged configuration?

Dave's balanced inverted XLR output is created with an opamp with limited current and higher impedance while the straight positive signal (and headphone out) side consists of discrete transistors.
This is why Dave wont drive a speaker load from XLR but can from RCA/ hp jack.

TT2 has both positive and inverted sides created equally with discrete transistors.
Hence why XLR balance doubles the power vs SE.

 

[flyte3333]

So the usual audiophile unregulated PSU would need to be changed by adding a SMPS DC/DC regulator.

There may be some unregulated but I'm not sure this is 'the usual'... ??

For example the popular for many years, sbooster linear PSUs...

 

[Jawed]

Just reading your system Jawad and interested if you'd tried other streaming solutions up front and whether they made a significant difference?

I ask because I run a pretty cheap WiiM Mini into my Mojo2 but it sounds excellent.

No I didn't try anything else. When I set up my "Playroom" dedicated room I originally used a laptop via USB, but I wanted a dedicated streaming device that would support Qobuz, Spotify and Tidal in addition to my networked PC server's music library and have nothing to do with Roon, while providing optical output.

I drive Node into HMS, which works for 192khz sample rate from Qobuz, with a 6m KabelDirekt optical cable (it's literally on the other side of the room from the rest of the hi-fi which is why the cable is long). A friend with a Node (2021 version, same as mine) has a terrible time with high data rates and long lengths of optical cable. It seems that the quality of the optical transmitter varies a lot with Node. It's also become clear that the optical inputs on HMS and DAVE also vary a little, so one socket might work and the other might not at a given data rate or cable length...

TOSLINK wasn't originally designed for 192Khz sampling rate, and most companies these days seem to be specifying compatibility with only 96Khz or less sample rate. So it's a minefield, but I struck lucky and I'm glad it works because it's part of my "anti-RF noise" setup mania. Though there are people doing more extreme things than me, so maybe not that manic...

The choice of streaming devices is improving. I have no interest in finding some magical device that might be better than my Node, as my system makes me deliriously happy. 3 years of learning, experimentation and setup tweakery have shown me that it's difficult to optimise a given set of components and any change of equipment potentially opens a minefield.

 

[Jawed]

TT2 has both positive and inverted sides created equally with discrete transistors.
Hence why XLR balance doubles the power vs SE.

Is this a bridge configuration?

Rob originally described TT2 as a derivative of his work on the DX amp concept:

But where TT2 really comes into it's own is raw power; you have the capability of 18W RMS using the balanced XLR, and 7W RMS single ended (SE). What's interesting about this is that when the power goes up, the measurements stay the same - no degradation as the load is increased. And you can drop the load impedance, and the linearity is unaffected, and this is absolutely crucial for driving tough loads. This project has proven very interesting, as there has been a lot of cross-fertilisation from the prototypes of the power pulse array project (which promises huge powers); indeed, the TT2 OP stage comes from the power pulse array design.

Yes the last 9 months has been very busy, with the TT2 and power pulse array - the DX amp. Initially TT2 had a beefed up Hugo 2 OP stage. And the DX amp had a much more complex OP stage - but this turned out to be not suitable. So this got redesigned, and I got the performance I needed - but then I realised I could update TT2 with this new OP stage, so it got added into the next TT 2 prototype. This increased the short circuit current delivery by 10 times, without sacrificing speed or propagation delay. The speed is crucial, as the 2nd order analogue noise shaper OP stage absolutely requires very fast switching speed, (of order of 30 nS) for phase margin and stability reasons.

so I'm curious if it's fundamentally a bridged configuration for TT2 using the XLR sockets and whether this represents how the DX amps will work.

 

[Reactcore]

so I'm curious if it's fundamentally a bridged configuration for TT2 using the XLR sockets and whether this represents how the DX amps will work.

It seems like a variation of bridging of just multiple OP transistors with a single feedback to the 1st amp stage. Its tricky stuff to get them to equally supply the current to the load using resistors in series with each transistor set. Specially on low levels.

But i havent done measuring in a TT2 so i cant be sure on this.

 

[freaknout]

No I didn't try anything else. When I set up my "Playroom" dedicated room I originally used a laptop via USB, but I wanted a dedicated streaming device that would support Qobuz, Spotify and Tidal in addition to my networked PC server's music library and have nothing to do with Roon, while providing optical output......

Many thanks and glad to see you're in a happy place

I'm very happy with Mojo 2, quite remarkable what has been achieved. I need to protect my wallet (and sanity and marriage) and keep away from the Hugo's!

 

[rkt31]

tried fiio ft3 with tt2 +hms few days back vs mojo 2. tt2+hms obviously ahead in terms of imaging and depth but then you lose the advantage of eq with tt2. to me fiio ft3 needs one or two click down at 20khz to deal with most commercial recordings. with very clean recordings fiio ft3 with tt2+hms is like the complete end game set up. i could barely go beyond -18L or -17L with most recordings. so tt2 in low gain out of headphone se out is enough and the cleanest way to drive headphones imo.

 

[rkt31]

topping released the D version of their cleanest power amp LA90. this has even better specs in s/n than earlier version. this version is not measured yet.

 

[Jawed]

It seems like a variation of bridging of just multiple OP transistors with a single feedback to the 1st amp stage. Its tricky stuff to get them to equally supply the current to the load using resistors in series with each transistor set. Specially on low levels.

But i havent done measuring in a TT2 so i cant be sure on this.

It seems there is a potential asymmetry in the way TT2 works, since both the single-ended (phono sockets) and XLR sockets are live simultaneously. So a low impedance on the phono sockets in addition to a low impedance across hot/cold of the XLRs puts more load on just half of the output stage. Seems like that might upset things generally...

 

[technobear]

It seems there is a potential asymmetry in the way TT2 works, since both the single-ended (phono sockets) and XLR sockets are live simultaneously. So a low impedance on the phono sockets in addition to a low impedance across hot/cold of the XLRs puts more load on just half of the output stage. Seems like that might upset things generally...

Which is why there is a clear warning in the user manual to not do this.

 

[Reactcore]

It seems there is a potential asymmetry in the way TT2 works, since both the single-ended (phono sockets) and XLR sockets are live simultaneously. So a low impedance on the phono sockets in addition to a low impedance across hot/cold of the XLRs puts more load on just half of the output stage. Seems like that might upset things generally...

Youre right, better not use them simultaneously on a low impedance load.

On high Z amp inputs it should be ok though.

 

[thePhones]

I hope the Dx amps are not completely canceled. Is there a specific reason why such a promising technology is set on a hold? When ever I listen with monoblocks I am saddened by the huge losses I get when compared to headphones out of Dave. I also know how amazing TT2 sounds when directly driving speakers, but I really like to listen loud with speakers (when watching movies I like cinema loud), so TT2 is not enough power for my speakers.

 

[Reactcore]

Is there a specific reason why such a promising technology is set on a hold?

My guess is commercial reasons.
They could undermine the sales of the Ultima amps.