The Centrance HiFi M8 thread - Page 36

Michael, they do make coax S/PDIF jacks in 3.5mm.  The Headroom Micro DAC and HM-801 use one for coax input.  But those two devices don't have them as a combo jack, for using with analog as well.  Is that part of the issue with not making it a coax jack instead of optical, which would of course also need a 1/8" to RCA coax adapter while optical would not?

Analog schmanalog.  Please don't confuse the issue again.  There are a couple of very good quality aftermarket 1/8" TRS to RCA coax SPDIF adapter cables available (Black Dragon and Double Helix).  And 3.5 mm SPDIF optical out still needs a 1/8" mini-Toslink to Toslink plug fiber adapter cable as well (of tenuous robustness) plus a SPDIF Toslink to coax converter, which I still don't know if there's a quality device presently available for passing 24/192 SPDIF coax output. [EDIT:  RDL FP-SPR1 and Tributaries AC100 have now been established for 24/192 throughput]

I for one would be perfectly happy with a 1/8" SPDIF copper wire TRS phone jack output, a 1/4" to 1/8" headphone adapter plug should I require it, and this whole SPDIF optical output (as accommodating as Michael has been to us so far) heartburn in my rear view mirror. 

Quote:

Originally Posted by aamefford 

I do have a question - When listening from unbalanced 1/4", is one effectively using only half the amp?  I believe this is the case with at least some balanced configurations.  If this is the case, is there any issue with putting many hours on part of the circuitry listening single ended (likely my primary), and much less hours on the remaining circuitry when listening balanced (less often to almost never for me, at least initially)?

Would someone with the definitive answer please answer this question.

Quote:

Originally Posted by qusp 

coax on mini is a hack, not a standard, RCA is bad enough, doesnt meet the 75ohm spec, mini would be complete mess, each type/brand of minijack would have a totally different impedance, none of which would be 75ohms. then of course with combo jacks you have the issue of detecting whether its a digital or analogue signal and the possible damage a mistake in that process would cause.

OK.  Cogent answer.  Evidently anything other than BNC connectors are a hack, at least as far as 75 impedance matching goes.  The Canare RCAP series with crimped contacts seems to be the least offensive among the RCA connectors.  No mini RCAP connector, unfortunately.

Also evidently the aftermarket 75 ohm mini to RCA SPDIF adapter cables are only specing the cable to the RG179 standard, not the connector.  How much would a single mini plug and jack pair contribute to total system signal degradation, tho, assuming fairly good impedance matching with the other RCA connectors? 

Quote:

Originally Posted by Saraguie 

Would someone with the definitive answer please answer this question.

OK Gang, I got the answer from a Technician at Centrance. Here it is and I quote:

My question:  "When listening from unbalanced 1/4", is one effectively using only half 

                       the amp?"

The answer:   "No, the signal is sent to all outputs equally. The amp works just the 

                       same when 1 or 2 sets of headphones are plugged in."

Quote:

Originally Posted by aamefford 

I do have a question - When listening from unbalanced 1/4", is one effectively using only half the amp?  I believe this is the case with at least some balanced configurations.  If this is the case, is there any issue with putting many hours on part of the circuitry listening single ended (likely my primary), and much less hours on the remaining circuitry when listening balanced (less often to almost never for me, at least initially)?

Quote:

Originally Posted by Saraguie 

Would someone with the definitive answer please answer this question.

The answer is no, the signal is sent to all outputs equally. The amp is powering the outputs the same whether 1 or 2 sets of cans are plugged in. This may cause one headphone of low impedance to sound louder than a headphone of high impedance when both are plugged in at the same time.

Quote:

Originally Posted by aamefford 

I do have a question - When listening from unbalanced 1/4", is one effectively using only half the amp?  I believe this is the case with at least some balanced configurations.  If this is the case, is there any issue with putting many hours on part of the circuitry listening single ended (likely my primary), and much less hours on the remaining circuitry when listening balanced (less often to almost never for me, at least initially)?

Quote:

Originally Posted by Saraguie 

Would someone with the definitive answer please answer this question.

Quote:

Originally Posted by Ksef10 

 

The answer is no, the signal is sent to all outputs equally. The amp is powering the outputs the same whether 1 or 2 sets of cans are plugged in. This may cause one headphone of low impedance to sound louder than a headphone of high impedance when both are plugged in at the same time.

Any guesses who the tech is that was very helpful to me all day today whether about the M8 or other questions?  

Thank you Kenny..........

Quote:

Originally Posted by bmichels 

Ok so i just sent à mail To their sales dépt To ask to pré-order one unit. I hope it is the right "procédure" :-)
I also asked a question that may find an answer here: With a Samsung galaxy S3 or Note 2, (android phone that have I believe implémented a standard USB audio), will the HiFi-M8 be able to go up to 24/192 kHz or will it have this stupid 16/48 kHz limitation ?
Tanks

That is very situation dependent. HiFi-M8 will be compatible with standard USB 2.0 Audio drivers. Since Android USB audio is not yet mature, the implementation of USB Audio is highly dependent on the phone manufacturer, and even greatly varies from model to model. In other words, if the phone is capable of 24/192 though USB 2.0, then M8 will be able decode it.

Quote:

Originally Posted by Ksef10 

 

The answer is no, the signal is sent to all outputs equally. The amp is powering the outputs the same whether 1 or 2 sets of cans are plugged in. This may cause one headphone of low impedance to sound louder than a headphone of high impedance when both are plugged in at the same time.

Thank you for this, HOWEVER - it does not actually answer my question - 

Situation 1) A single set of balanced headphones plugged into the for instance XLR4 jack - Right channel both + and - are actively amplified, left channel, both + and - are actively amplified, so effectively 4 active signals.

Situation 2) A single set of single ended headphones plugged into the 1/4" jack - Right channel + is amplified, - goes to common ground, Left channel amplified, - goes to common ground, so effectively 2 active amplification channels.

I know for instance a 4 board balanced beta 22 works this way.  When a single ended pair of headphones is is plugged in, effectively 2 boards ( - left and - right) are not doing anything.

Is this also how the HIFI-M8 works?  If not, how does it work when driving balanced headphones, and when driving single ended headphones?  Is it the case that half the amplification circuitry is not really doing anything when operating single ended?

Some answers:

> I do have a question - When listening from unbalanced 1/4", is one effectively using only half the amp?  

From a simplistic standpoint, in the "brute-force" scenario, your assumption above would be correct. If you are worried about the amp's performance degradation, then I can assure you that there is nothing to worry about. Modern silicon amplifier technology doesn't really degrade with use (or lack of use). However, we had to deal with a related, yet entirely different issue while developing the product, so let me explain some more. If you have a wall-powered device, you probably don't need to do anything. The extra amps don't care -- they would just sit there doing nothing, warming up the environment and slowly contributing to global warming.

But there is an important distinction between wall-powered and battery powered devices. In a portable device such as HiFi-M8, we cannot afford the unused circuitry to "just sit there", consuming power for no reason and frivolously draining the battery down. To combat this drawback, we have devised ways to prevent unnecessary power consumption, while maintaining full sound quality. CEntrance had to make sure that battery power is conserved, especially since we are using very powerful headphone amps, which, if left un-managed would take the battery down in no time. Suffice it to say that our advanced battery conservation technology prevents the above scenario from happening... Less global warming, more playing time!

> Also, with the "modular" design - would the end plates that have the S/PIDF input and / or 3 pin XLR combo outputs be user changeable pieces?  Or Centrance changeable pieces?

We don't really think these would be user-changeable. We expect to configure each unit a certain way before it leaves the factory in Chicago. We don't plan to offer side plates for sale - the amount of support we'd need to provide would make this prohibitive.

I totally get where you are coming from. We simply couldn't find a good part in the time available. We were looking for a reliable supplier, good lead-times, good pricing, good specs, all that. We had two options - find a combo optical jack or a combo coaxial jack. We found the optical jack, but not the coax. Given more time, we would have probably found both, but since we are under the gun to ship, we needed to make a decision and move on. There is always the next rev., although I know this sounds like a cop out...

I am hoping the volume bar on my ipod touch 4G/iphone 4 will not be visible when plug in via usb/lod to the hifi-m8.

It is non-functioning but visible on my Fostex hp_p1 (with my ipod touch 4G/iphone 4 but Not my iphone 3G firmware 4.2.1), it just bugs me for some reason, its an visual aesthetic thing.

*In my experience:

Fostex hp_p1 and CLAS visible.

Go-dap X and Sony PHA-1 non-visible.

A new question for Michael, I've seen both silver and black front/back face plates in the various mock ups, will we have a choice of color? I'll state for the record, my preference is for black. :-)