Prism Orpheus - sorry, how to use?

[PCmusic]

Dear Community

 

My question may look a bit silly - I have to admit I am not a pro guy. Two years ago I started to use Weiss DAC2 directly feeding my poweramp, with PC and foobar as source (Windows XP).

 

The reason I am interested in Orpheus is because its range of capbility. I am planning to revive my old LP collection, and a pro guy told me to use 'flat response' preamp, and then after some search without knowing what he said, I have my eyeball fixed on Orpheus. I almost have bought two extra things - a phono preamp and a preamp for my MC cartridge. But it seems Orpheus would do all things for me - DAC, playing LPs, CDP (still have one), and even ripping LP.

 

The thing is as I am not a pro guy, after some exploration (and reading the manual), I still can't figure out exactly how I could use Orpheus to do the above things. I have listed my questions below, and hope some may help answer - and please understand I have been a 'consumer' type of audiophile but am willing to learn more how to operate the pro-Orpheus:

 

1. How could I play vinyls through Orpheus? I know I can plug in the turntable to the gear, but what is the signal path? Does the LP signal (analogue) go to Orpheus, being digitalized, and then being sent to its own DAC, and then transformed back to amplified analogue signal to the poweramp? What is the role of my PC here (it seems to me the PC doesn't have a role here)? Is the above path wrong? What is the correct path?

 

2. What is the signal path for digitalizing LPs? I know this question is related to 1. But as I can't figure out the signal path in 1., this question is more complicated for me.

 

3. How could I play CDs through the CDP? Again, what is the role of the PC here? Just controlling how Orpheus 'operates'? In this case - telling Orpheus how to input and output the CDP digital signals through the coaxial connecting my CDP to Orpheus?

 

4. Finally, when I use DAC2, I thought my PC primarily 'feeds' signals to DAC2, based on the latter's clock. It's to me more a kind of 'one-way' communication. But if I digitalize LPs, I must use Orpheus to send the digitalized analogue signals of the LPs to the PC, right? Then how is it done? Through firewire? If this is the case, could I assume there will always be a kind of two-way communication between the PC and Orpheus? First, the pc tells Orpheus what to do with the LP signals, and second, the pc also 'takes in' the digitalized signals in the format of FLAC, Wav, and so on.

 

Sorry, I am quite confused. All along, I have been using cables to do 'one-way' communication between gears. But the complexity of Orpheus is beyond my knowledge. I am very interested in its functionality - one powercord, doing things that I would have bought several things to do, with good quality as suggested by many users.

 

I look forward to hearing from some patient guys who are willing to shed some light on the questions I asked above. And thanks in advance.

 

 

[jnrich]

OK, I'll take a stab at this, as I use a similar setup (Metric Halo ULN-2) to listen to and record vinyl.

 

First, to get the info out of the grooves, you need two things: analog gain and an RIAA correction. You can do both of these things using your Orpheus.

 

Here's the signal path, as I understand it:

 

1. Low level analog signal from phono goes into the analog inputs on your Orpheus.

2. Dial in desired analog gain from the mic preamps on Orpheus.

3. Analog signal is converted to digital via Orpheus' internal analog to digital converter (ADC).

4. Digital signal is routed via firewire to computer for processing. Here, my Metric Halo has a software package called MIO that handles routing of digital signals and subsequent processing. I use this utility to apply the RIAA correction in the digital domain. If the Orpheus doesn't have this ability, you will need software such as Pure Vinyl to apply the digital RIAA correction; you can also use this software to set up the acquisition parameters for digitizing your vinyl and storing your files. If you are digitizing, then the data are dumped to a hard drive for storage.

5. If you are listening to your vinyl, then the processed digital file is routed back (again via firewire) to the Orpheus where the internal digital to analog converter (DAC) does its thing, whereupon the analog signal is routed to your preamplifer on on from there in the normal way. You could also use the S/PDIF out on the Orpheus to route the digital signal to an external DAC of your choice, though I hear that the internal DAC on the Orpheus is excellent.

 

This sort of takes care of questions 1 and 2. As far as using a cd player, I'd skip that altogether and rip my disks to the computer work from playlists, again using Orpheus as your DAC.

 

Hope this helps!

 

[barrows]

Jerry's website, 10audio.com, he uses the Orpheus both for digital playback, and as a high end phono stage, and talks about doing so in detail.

Chris, I hope mentioning another site is OK with you, please delete this and alert me if there's a problem.

 

[PCmusic]

Your explanation is very clear. Thank you very much!

 

But one more question - so will 4 and 5 happen 'simultaneously' this way through ONE SINGLE Firewire cable?:

 

1. "Digital signal is routed via firewire to computer for processing"

 

 

2. "If you are listening to your vinyl, then the processed digital file is routed back (again via firewire) to the Orpheus where the internal digital to analog converter (DAC) does its thing"

 

If so ... I never know Firewire could work 'two-way' ...

 

thanks ...

 

[PCmusic]

thanks barrows ... i have read the review in 10audio. I asked since my questions are not directly answered in his review ... but thanks for reminding me.

 

[jnrich]

Yep, Firewire transfers signals both ways.

 

One thing I forgot to mention that you should know about, and that's proper loading of your cartridge.

 

If you go directly into the Orpheus, your cart will be seeing the input impedance of that device. That may or may not be ok, depending upon what type of cart you are using.

 

I have found that both low output MC carts I have (Shelter 901 and Zu Audio modded Denon 103) work fine directly into my Metric Halo ULN-2, whose input impedance is 33 kohm (I believe...). Such cartridges are relatively insensitive to input impedance, but a MM cart needs to see 47 kohm on the input. Believe me, I tried running such a cart directly into the Metric Halo, and it sounded horrible.

 

One option I have thought of is using something like the Hagerman Piccolo to get the correct input impedance for your cart, and then run the output of the Piccolo directly to the Orpheus. I have a friend who has the Piccolo, and I'm thinking of trying this myself; at least you can then experiment with different loadings without being at the mercy of the input impedance of the recording device.

 

[Panelhead]

Somewhere around 3K is more common. Have no idea what the ULN-2 and Orpheus are. But most moving coils sound better at 2 1/2 - 4 times the cartridge internal impedance. That is closer to 100 ohms.

 

 

George

 

[jnrich]

You are right; I checked the MH site, and the input impedance is 3.3 kohms, not 33 kohms. My bad....

 

I'm running my Shelter 901 into a Klyne pre right now at 500 ohms and really like the sound.

 

[barrows]

Jerry at 10audio did not find the mic pres of the Orpheus quiet enough for low output MC cartridges, as I recall he ended up using a step up transformer into the mic inputs to get some additional quiet gain.

 

[Panelhead]

This makes connecting a turntable to an interface a challenge. The RCA connectors and single ended leads to the balanced inputs of the mic preamps.

If the tonearm is rewired with a real balanced connection, ground to armtube and +/- from cartridge the mic pres will most likely be quiet enough. But then the arm will only work with a phono with XLR, DIN, or other 3 pin connectors.

There is a great reason why microphones are ALWAYS connected with 3 pin balanced connections. Noise rejection.

I have been rewiring my tonearms and using 3 pin locking DIN connectors for 20 years. Fought hum issues with tube phono stages and hum magnets, or step up transformers. Swapping to balanced leads into the hum magnet helped. Then balanced into the phono stage with it doing the Balanced to SE conversion.

If I can get by without using one of the hum magnets it is better. But limited gain or noise may make them very necessary. Most mic pres offer up to 75 dB of gain, does this not work well enough for most 0.25 - 0.50 mV cartridges?

 

George

 

[4est]

What do you mean by "hum magnet"?

 

[barrows]

Yes, 75 dB of gain should be plenty for all MC cartridges. What Jerry reported was that there was plenty of gain with the mic pres in the Orpheus, but that using all of their gain became too noisy. He opted for a step up transformer to add some quiet gain, and then turned down the gain on the mic pres appropriately to lower the noise floor.

Good point about balanced connections-cartridges are balanced devices, and should be run balanced whenever possible to avoid noise pickup.

 

[PCmusic]

I have a old MC cartridge which is rated as 0.1mV, with load impedance of 10 ohms and output impedance of 6 ohms. Seems I must use a step-up transformer for this? And I don't know the implications of its load and output impedance. Please advise.

 

I also found this in Orpheus' website:

 

"Most vinyl decks have a ground wire separate from the audio connectors. Connection of this wire for lowest hum is often a matter of trial and error. Ideally this should be connected to Orpheus' analogue signal ground (the outer of the instrument input jacks, or pin 1 of the mic input XLRs). Since no dedicated terminal exists on Orpheus, it is usually easiest to connect the wire to the outer of one of the deck's unbalanced output connectors. In some situations, a direct connection to local mains ground may work better."

 

Is this how you connect the ground wire to Orpheus? Years ago, I just attached the ground wire to the special 'knob' at the preamp.