The JT-11SSP-7MPC is listed as a 600 ohm to 600 ohm repeat coil transformer at the bottom of this page:
Line Input | Jensen Transformers
I couldn't use what Jensen calls an output transformer, as those only work well when driven from a very low source impedance. (Their competitor Lundahl even recommends negative source impedances.) Hence the use of this repeat coil transformer.
Datasheet:
https://www.jensen-transformers.com/wp-content/uploads/2014/08/jt-11ssp-7mpc.pdf
Mind you, they also have this note on their home page:
"COVID-19 UPDATE: Jensen Transformers is still closed to the public, however we are now available by phone and email. Please be patient as stock is limited and all orders will be updated with an ETA. If you have any questions visit the contact page for more info."
Line Input | Jensen Transformers
I couldn't use what Jensen calls an output transformer, as those only work well when driven from a very low source impedance. (Their competitor Lundahl even recommends negative source impedances.) Hence the use of this repeat coil transformer.
Datasheet:
https://www.jensen-transformers.com/wp-content/uploads/2014/08/jt-11ssp-7mpc.pdf
Mind you, they also have this note on their home page:
"COVID-19 UPDATE: Jensen Transformers is still closed to the public, however we are now available by phone and email. Please be patient as stock is limited and all orders will be updated with an ETA. If you have any questions visit the contact page for more info."
I hope this helps:
DSD: Philips/Sony trade name for a single-bit sigma-delta modulate, I've tried to explain in the article what sigma-delta modulation is.
Raw DSD or native DSD interface: interface that simply puts the DSD stream of each channel on a separate wire with a common bit clock on another wire. Often an I2S interface is abused for this: the lines that carry the serial data and word clock in I2S mode then become the two stereo channels in native DSD mode, while the bit clock remains the bit clock.
Mute: signal indicating to the DAC that its outputs must be made silent, sometimes used to prevent clicks and other unintended sounds when switching between formats.
De-emphasis: a peculiarity of FM mono radio is that the noise in the channel (atmospheric noise, thermal noise, noise of the radio front-end) is converted to audio noise that increases with 20 dB/decade with increasing frequency at the output of the FM demodulator. As the high-frequency components in audio are usually much weaker than the low-frequency components, an equalization is used that enhances the high frequencies in the transmitter and attenuates them again in the receiver. This is known as pre-emphasis and de-emphasis. The de-emphasis filtering in the FM receiver much suppresses the noise at high audio frequencies at the FM demodulator output. The disadvantage is obviously that audio signals with unusually large amounts of treble can't pass through an FM broadcast signal chain unscathed.
While this scheme is very effective for FM broadcasting, especially in mono, it is much less effective and much less useful for CD audio, while the disadvantage remains. Nonetheless, the CD standard features a pre-emphasis and de-emphasis scheme. It was sometimes used on early CDs, later its use became very uncommon.
It can only get DSD through an optical output if it supports DoP, do you know if it does?
(DoP stands for DSD over PCM, which is a trick to get DSD data through interfaces that are intended for PCM. The name is a bit misleading as it suggests that the DSD gets converted to PCM, which is simply not the case. See https://dsd-guide.com/sites/default/files/white-papers/DoP_openStandard_1v1.pdf for all details.)
Yes, that should do it.
Looks fine to me.
Just had a look through the manual and I am none the wiser; I've attached the relevant couple of pages. The term DoP is not used but it does say PCM. Even multichannel DSD is output as 2 channel PCM via the digital ports so perhaps there is other processing happening in there.
This is the manual of the Blu Ray player, stating it can only output DSD via the HDMI output and that it converts it to PCM for the other digital outputs. When you look at section 7, page 41, it says: "When playing copyright-protected discs or files, the signals are output with the sampling frequency limited to 48 kHz or below, regardless of this setting." I think that's a cryptic way of stating that DSD from SACDs gets converted to 44.1 or 48 kHz sample rate audio.
I was wondering about that HDMI interface you had found, does that support DoP?
I was wondering about that HDMI interface you had found, does that support DoP?
See this link for where I first picked up about the HDMI box and DSD output from BluRay players (Oppo UDP-205, UDP-105 and several generic Sony BluRay).
I don't know if that HDMI interface supports DoP, but it likely does given that several BluRay players seem to work through the unit. Might be worth getting the box to try out, although I am not sure how I could tell whether my SACD output is as DSD or DoP or PCM.
I don't know if that HDMI interface supports DoP, but it likely does given that several BluRay players seem to work through the unit. Might be worth getting the box to try out, although I am not sure how I could tell whether my SACD output is as DSD or DoP or PCM.
No experience yet, but the upper pair of ECC81's in each dac core still have to drive the output stage and I think valve quality may still play a part. Not sure. I'll start with some cheapies but at some stage will put in some 6N23P.
Also have some ECC801S here that I will try in the clock circuit in place of the ECC81. No idea if it is worthwhile, but the Telefunken ECC801S are a very low noise tube.
I assume that you know that the audio 'HDMI' output from the interface isn't actually HDMI but is simply using the physical cable as a means to transmit the audio via LVDS (low voltage differential signal). The principle is also used by Twisted Pear for their teleporter products, though they use RJ45 network cables.
As far as I'm aware, there are at least two 'standards' of pin assignment for the HDMI hardware-based i2s transport mechanism. One seems to be known as the 'PS Audio' standard but I don't recall the other? Audiophonics do a range of HDMI LVDS products that might give some clues?
DIY Interfaces | HiFi Sono DIY | Audiophonics - Audiophonics
Sorry if I'm teaching granny to suck eggs.
As far as I'm aware, there are at least two 'standards' of pin assignment for the HDMI hardware-based i2s transport mechanism. One seems to be known as the 'PS Audio' standard but I don't recall the other? Audiophonics do a range of HDMI LVDS products that might give some clues?
DIY Interfaces | HiFi Sono DIY | Audiophonics - Audiophonics
Sorry if I'm teaching granny to suck eggs.
Is the audio out HDMI on the blu-ray player real HDMI or one of the audio flavours using the HDMI hardware.
FWIW, I've considered using Twisted Pear's Teleporter modules in conjunction with their Otto II switchable mux to route I2S/DSD to different DACs. Source would be a Beaglebone Black.
FWIW, I've considered using Twisted Pear's Teleporter modules in conjunction with their Otto II switchable mux to route I2S/DSD to different DACs. Source would be a Beaglebone Black.
What I gather from the information in the link you provided, in Ray's link, in the manual of the BluRay player and a bit of educated guesswork is this:
1. The BluRay player puts the DSD audio from an SACD on its HDMI output (real HDMI, not I2S via an HDMI connector) as long as whatever is connected to the HDMI output does not indicate that it can't handle video resolutions above 480 lines. The other outputs, optical and coaxial S/PDIF, only get DSD audio decimated to PCM with a sample rate smaller than or equal to 48 kHz - chances are it gets decimated to 44.1 kHz PCM.
2. The Chinese interface box has I2S outputs that can also work as raw (native) DSD outputs. It can take DSD data from the HDMI interface and put it on its raw DSD outputs. Whether it also supports DoP is unclear. The box has two I2S outputs, one working with LVDS levels connected via an HDMI connector and one with presumably 3.3 V CMOS levels connected via the white connector right next to the LVDS output.
3. It would therefore be handy if a circuit that switches various I2S signals to the single I2S input of the DAC supported raw DSD, 3.3 V CMOS and LVDS levels.
I'm trying to come up with a circuit with four inputs that fulfills the requirements of point 3. It will consist of a couple of three-state buffers and LVDS receivers with three-state outputs and some glue logic.
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