[Dandoudou]

TEAC ud701n
If anyone has any experience with one let me know!

I have one. I listened to it, and was very favorably impressed.
The Teac has a LAN input, and it replaced the Terminator of a friend together with his SoTM streamer, and his DI-20HE. This DAC is excellent!
I reported that to a friend on this forum, and he bought it. It replaced his A26.
I'm going to organize a comparison between the TEAC and my R26 + DI-20HE.

 

[camrector]

Yes please! Keep me posted!!

 

[m-i-c-k-e-y]

Dude I’ve been hunting and hunting for the R26 upgrade path. I think I have finally found something that might be it.
Checks the all the boxes for me but I haven’t heard one yet.
TEAC ud701n
If anyone has any experience with one let me know!

Have a thread in here a while back.

Edit: Here it is https://www.head-fi.org/threads/teac-ud-701n-discrete-dac-network-hp-amp-preamp.966677/

Just came in late for me...if it came before, will buy it a heartbeat. Just perfect for me.

 

[Dandoudou]

Yes please! Keep me posted!!

I have to travel abroad. When I'll be back, in late June, my friend will bring his Teac to my home, and we will take the time to make serious comparisons between the two DACs.
The Teac also has a good pre amp, so there are many things to try.
I'll report on this thread and on the thread of the UD-701N.

 

[rodthebod]

Yeah I was starting to think the same thing, despite having contributed a few technical posts here to an effort to share understanding in what is a complex and contentious area. It's a tricky balance.

lt's British humour....The Scottish are known for being careful with there money,being Welsh and fellow Celt ..l get it.

Aye Lad! I am actually from the Highlands........ I was taking the post initiator out of myself.

 

[Stellabagpuss]

Last post on this particular slur. We're also known for being readily offended by English tropes. End.

Is this Hi Fi ? Or is English Tropes a new DAC that's End Game?
Must count me and Rodders out..we are not English

 

[Clivem2]

The video I posted explains what the clock synthesizer does.
The internal “clock”/oscillator in the Gustard would be bypassed and not be working with and external clock. The internal k2 clock synthesizer is and would use the LB or whatever external. A square wave is made up of a whole sequence of "harmonics" which make the signal "square."
Attenuating these harmonics makes the signal "rounded" which means the edge slope is a lot less, resulting in phase modulation. Also square waves are highly sensitive to impedance mismatches between components, cables, connectors etc etc. ie more phase modulation.
Why it works?
Well a better oscillator is what makes most if not all clocks better than internal ones. Here we don’t have that happening.
I’m sticking with my original statement that some degree of 2nd order harmonics are being produced.
3rd order are as well and that’s not a good thing.

I have yet to get to the the end of the video you posted (thanks, it is good). I’m not expecting it will cover the specific K2 implementation by Gustard.

I could be wrong but given my experience of what happens with the the R26 external clock signal is lost, I would be surprised if the internal clock is fully bypassed when the external clock input is selected.

Having seen the images from a ‘scope about the influences of power supply and 50R cable quality, it’s obvious these things make a significant differnce though I can’t at all quantify how this relates to the measured specs. We don’t know the measurement environment for the LB clock. We can’t even be sure how the clock was measured that’s in the R26…if indeed it was measured within the DAC.

Is the clock inside the R26 sine wave or square wave? Might the R26 respond better to a square wave?

 

[Jake2]

I have yet to get to the the end of the video you posted (thanks, it is good). I’m not expecting it will cover the specific K2 implementation by Gustard.

I could be wrong but given my experience of what happens with the the R26 external clock signal is lost, I would be surprised if the internal clock is fully bypassed when the external clock input is selected.

Having seen the images from a ‘scope about the influences of power supply and 50R cable quality, it’s obvious these things make a significant differnce though I can’t at all quantify how this relates to the measured specs. We don’t know the measurement environment for the LB clock. We can’t even be sure how the clock was measured that’s in the R26…if indeed it was measured within the DAC.

Is the clock inside the R26 sine wave or square wave? Might the R26 respond better to a square wave?

A while back I did a lot of experimentation with various R26 inputs (ethernet, s/pdif and I2S were the ones I tried) and ext clock on/off combinations as well as NOS on/off and DSD direct ON/OFF. It seems - from the audible delta in sound quality when toggling the ext clock on/off - the external clock is always in play when Ext 10mhz ON is selected for all those inputs irrespective of NOS/DSDD on/off setting. My understanding is the K2 synthesiser is always in play generating the 44khz or 48khz multiple required by the R26 DAC section depending on the sample rate family of the input signal, irrespective of NOS/DSDD or ext/int clock settings. All that changes with selection of internal vs external clock is where the K2 sources the clock signal from which it then multiplies or uses to ‘synthesise’ the required frequency needed by the DAC. (I havent watched the vid yet but hopefully this is consistent with it)

To date I’ve found sine works better than square with LHY clocks and the R26, irrespective of cables used. This could be due to limitations in the sine-square conversion circuit in the LHY clocks or the receiving circuit in the R26. Not sure.

 

[Clivem2]

A while back I did a lot of experimentation with various R26 inputs (ethernet, s/pdif and I2S were the ones I tried) and ext clock on/off combinations as well as NOS on/off and DSD direct ON/OFF. It seems - from the audible delta in sound quality when toggling the ext clock on/off - the external clock is always in play when Ext 10mhz ON is selected for all those inputs irrespective of NOS/DSDD on/off setting. My understanding is the K2 synthesiser is always in play generating the 44khz or 48khz multiple required by the R26 DAC section depending on the sample rate family of the input signal, irrespective of NOS/DSDD or ext/int clock settings. All that changes with selection of internal vs external clock is where the K2 sources the clock signal from which it then multiplies or uses to ‘synthesise’ the required frequency needed by the DAC. (I havent watched the vid yet but hopefully this is consistent with it)

To date I’ve found sine works better than square with LHY clocks and the R26, irrespective of cables used. This could be due to limitations in the sine-square conversion circuit in the LHY clocks or the receiving circuit in the R26. Not sure.

What I had in mind re internal/external clock switching was that this happens totally glitch free when music is playing…it did for me when I was using a loose bnc on a very stiff cable. Of course it must be possible to engineer the circuit to do this but I would have expected a tick, pop or momentary drop out when EXT ERR occurs as the clock reverts to the internal clock. Yes, I’d too expect the K2 synthesiser to be in operation permanently.

It sounds like square wave conversion brings another variable to all this.

 

[Jake2]

What I had in mind re internal/external clock switching was that this happens totally glitch free when music is playing…it did for me when I was using a loose bnc on a very stiff cable. Of course it must be possible to engineer the circuit to do this but I would have expected a tick, pop or momentary drop out when EXT ERR occurs as the clock reverts to the internal clock. Yes, I’d too expect the K2 synthesiser to be in operation permanently.

It sounds like square wave conversion brings another variable to all this.

Yes I was surprised too at the mostly seamless playback* as my previous DAC, an SMSL AK4499 VMV D2 produced terrible static when no ext clock was connected and loud pops when switching.

*from recollection the exception is DSD direct where there is a pop/glitch when toggling ext clock on/off.

 

[Clivem2]

Can someone decode the blurb from the Afterdark site? Ie:

• Yes, it Gustard R26 R2R DAC is using a programmable Ultra High Speed CPLD to perform digital re-clock functions using 2nd PLL, and has ability to perform re-clock using External 10M Master Clock

This taken from https://audiophilestyle.com/forums/...rd-r26-r2r-dac-x-giesemann-ocxo-master-clock/

 

[Luvdac]

My very non technical 2 cents on clocks:
I have just recently mounted a clock card sotm sclk ex in my server and there was an immediate uptick in sound quality. This while the r26 was using the lhy ock2 as master clock. I then connected the sclk ex to the ock2 and the soundstage really opened up. So currently the lhy is the 'conductor' to the server and r26. My take on this is that there is much to be gained by having a single master clock keeping the various digital equipments in step with each other. I have no idea of the technicalities involved, it's my ears doing the talking.

In the picture the clock board is the one mounted vertically behind the front plate.

 

[m-i-c-k-e-y]

@Luvdac

Is your M/B a SMB-Q370? Looks like it. JCAT Optimo Nanos powering JCAT USB and Netcard (assuming all XE since I could spot the Emerald OCXO in your net card and no Femto clock on your USB). Nice system! SSD? couldn't see. OS and Player?

Before, wanted to go this route (like your setup). But later was convinced a good streamer + DDC could fill the bill. And later decided on my present system.

 

[Jake2]

@Luvdac +1 re nice server. How do you connect your server to the R26? Oh wait a sec, IIRC you use a Jcat USB XE with handmade silver cables… is that you?

Since we’re showing and telling I just took the lid off a new Afterdark Rosanna Diretta streamer I got a week ago as part of the Audiophilestyle group buy and am still in the process of setting up with the expert direction of @Dandoudou . My first AD - a bit of carbon p0rn. USB, ethernet, FMC and streamer are all clocked by the external clock, which will be my OCK-2. If it doesn’t beat the R26 LAN via USB direct or via the U18 - and TBH I’m unsure how it’ll go as the R26 LAN is singing with my tweaks - it’ll be an expensive experiment and a testament to how good the R26 internal renderer is.

 

[rodthebod]

LB inside R26 progress.

I have been using a pair of Neutrik XLR-RCA adaptors on my R26 and I have been busy trying out the XLR-RCA adaptors compared to using the dedicated RCA outputs from the Gustard R26 outputs this morning. I have been living with the adaptors which give a pseudo balanced output, so not proper balanced but the voltage is higher at 5v.

I know that the increased voltage will give more volume as you kindly pointed out and when changing over the connections I tried to compensate for this. Listening to Diana Krall Sway I was definitely hearing more detail and texture on the brush on high hat at the beginning of the track with the XLR connection, the sound is just more alive, the difference is subtle but there.
I swapped over several times to confirm this, I must try the Jennie test (my dear wife) for confirmation but she was busy doing shopping etc. I should try the test with using my single ended Avondale Grad One solid state preamp which hasn't been heavily tweaked by myself like the Conrad Johnson clone has.

Next, after a suggestion from a prominent 'The Audio Standard' forum member on the LB thread, I tried disconnecting the BT antenna cable from the R26 vertical board with the streamer and LAN USB and Optical connections. I thought that the antenna would only be powered when the Bluetooth input was selected as the desired input, I think this is incorrect now. I placed a bit of heat shrink over the exposed antenna connector as I didn't want it to short anything on the motherboard. I just left the connector on the PCB open with no blanking.
The result, after trying to hear small difference's between XLR and RCA, was quite a wow moment, disconnecting the BT antenna made a big difference in detail and space around instruments instantly. A definite improvement. It may be that the LB PCB is being affected or that the BT antenna degrades the onboard R26 clock?

If the BT antenna is making this much of a difference then it is logical to assume that further screening is a good move around the LB. My next move.

Can other please try this disconnection of the bluetooth antenna internally, I'd like to hear back from others if it effects R26 owners without an internal Leo Bodnar clock!