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Topic: It's time for my first DAC and quality amp. Can anyone help? (Read 8245 times) previous topic - next topic
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It's time for my first DAC and quality amp. Can anyone help?

It seems I have 2/4 of a decent audio setup.  I have a newer iMac (playing FLACs) and I have a pair of Martin Logan Motion40's.

The weak link is that I'm running out of the Mac, via toslink, into a $400 Onkyo 5.1 receiver.  There doesn't seem to be anything I can do to make the audio sound really good with that amp.

I'm looking at the Yamaha AS2000 amp (based on many very good reviews out there) but it doesn't have a toslink input, so I assume that means it doesn't have a DAC onboard.  It does, however, have balanced inputs, which I've never seen on home audio gear.  I associate balanced inputs to guitar amps and mixer boards.

So what am I looking for here?  Am I looking for a DAC that takes toslink-in and outputs to three-pin balanced?  Or how do people do this?  (Not looking for portable or headphone based.  This is for a listening room with a substantial amp and floor standing speakers.)





Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #1
Are you able to measure what it is you think is wrong with your DAC and amp?

Without corroboration (even with objective evidence provided from a 3rd party), I'm afraid this community cannot be of any benefit to you.

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #2
"I associate balanced inputs to guitar amps"

Balanced inputs are practically nonexistent on guitar amps.  Balanced outputs are a relatively new feature which began to appear around the turn of the century and is still far from universal.  I could go on about speaker compensation, but that would be off-topic.

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #3
Let me rephrase the question to take out the issue of the amp I currently have. 

I want to create a system of Mac computer playing FLACs ... to DAC ... to Yamaha AS2000 amp (which features balanced 3-pin inputs, if that matters) ... to Martin Logan Motion40 speakers.  Nothing portable, nothing headphone-oriented.  No turntable, no CD player.

I know nothing about DACs and I'm overwhelmed by the abundance of options and terminology that makes no sense to me. 

Do DACs come with balanced 3-pin outs?  Would that be of value to me?  Or is RCA-out from a DAC good enough?

Is there a difference between going from Mac to DAC via USB vs toslink?


I suppose if I understood those items I might be armed with enough info to start wading through the choices in DACs out there.


Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #5
"i got a fever and the only prescription is more cowbell"

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #6
Quote
Do DACs come with balanced 3-pin outs?  Would that be of value to me?  Or is RCA-out from a DAC good enough?
Over short distances there is no advantage.  Over long distances the balanced (3-wire) connection is more immune to noise pickup.    Balanced connections are the pro studio standard so if you have a pro set-up there is an "advantage" of everything being standardized (and better noise immunity). 

You can find pro DACs with balanced outputs.  Here's one.

Quote
Is there a difference between going from Mac to DAC via USB vs toslink?
If you're not hearing noise, the DAC built into your Mac probably sounds just as good as any other DAC.  Noise is usually the only thing to worry about.  It's cheap & easy to make a DAC that's better than human hearing, and the other two important parameters/factors (distortion and frequency response) are almost always better than human hearing.   

The DAC built into your soundcard is probably only 2-channel stereo, so if you want surround you'll need something external.   

With a USB DAC any decoding/decompressing is done by the computer.  With TOSLINK, the decoding is done in the DAC/receiver, although some formats can be decoded by the computer and sent as "raw" PCM to your receiver.   

Some stand-alone TOSLINK or S/PDIF DACs can't decode any compressed formats (so they can't play Dolby audio from a DVD.)  But, any audio/video receiver can decode the standard DVD formats.

Since toslink is optical, there is no electrical connection which helps to minimize ground loops (noise again).

TOSLINK doesn't support the various Blu-Ray formats.    With a 5.1 or 7.1 channel USB soundcard, you can play any DVD/Blu-ray formats that your software supports. 

HDMI supports all of the DVD & Blu-Ray formats.

Quote
There doesn't seem to be anything I can do to make the audio sound really good with that amp.
Assuming there's nothing wrong with your receiver/amplifier...  Try some equalization.    Or, get a subwoofer.    Or, try re-positioning your speakers.  Or, try some new music.      Or, try adding some surround speakers with some of the soundfield effects on your receiver.  (I like a little reverb in the rear channels.)   

There's a chance it's the room acoustics...  Have you ever had your speakers in a different (perhaps larger) room?  Have you ever listened to them outdoors? 

I've used my speakers in a DJ setup in a "dance hall" a few times and to my taste, they sound a LOT better in a big reverberant room than in my living room.    Then, there are some people who like a "dead" room.

But, I'm guessing you're just bored with the sound.  ;)





Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #8
Quote
Balanced connections are the pro studio standard so if you have a pro set-up there is an "advantage" of everything being standardized (and better noise immunity).  You can find pro DACs with balanced outputs.

.
.
.

If you're not hearing noise, the DAC built into your Mac probably sounds just as good as any other DAC. 


THANK YOU, DVDdoug, for a helpful reply.  Okay, I got from the link you gave me for the pro balanced output DAC that that's not a common feature, except among the seriously high-end people. 

Regarding what you wrote about noise from my in-Mac DAC, here is what I'm dealing with.  I've got a cheapo ($400) Onkyo 5.1 receiver, but I'm just using it for stereo.  I'm trying to get rid of my CDs by ripping everything to ALAC so I can play all my music in iTunes.  I've got a CD player hooked up via RCA ... and my Mac hooked up via toslink. 

I took a few late-era CDs (ie, well recorded) and ripped them to ALAC.  When I play the CDs and turn the amp up to a normal 20 (out of 80) on the Onkyo volume I get clear reasonable-quality sound.  When I play the ALAC ripped from the exact same CD, at the same volume I get trace moments of distortion, I guess you would call it clipping, at certain points.  It's not universal across the recordings.  It's triggered by certain moments like when a singer hits a certain note or the first note after she comes in after a bass solo.

The only relief I found so far was to go into iTunes EQ and turn the iTunes preamp all the way to the bottom rung ... "-4" ... and then more than double the volume on my amp to almost 60 (out of 80).  That eliminates the clipping, but of course introduces some constant hiss from the loud volume on the amp.

So I don't know if that's the Mac's DAC noise that's causing the clipping and if it would be eliminated by buying a quality DAC.  I haven't found any way to get rid of it other than what I wrote about, dropping the iTunes preamp to the lowest level and then cranking my amp. 

On a side note, I don't know much about audio, but I do a hear a BIG difference in different amps, so I'll be shopping quality amps soon, but for now I'm wondering if the DAC on my Mac might be what's causing the clipping.

Again, CD into the Onkyo via RCA ... no clipping at all.  Just clean, albeit bland, music quality.

That same CD ripped to ALAC (using XLD software) and played from the Mac to the Onkyo via toslink ... I get what sounds like clipping at spots throughout the tune.

I'm also not listening to the music loud.  Either desk-work volume or a little louder sitting in my listening chair and listening intently.

Any suggestions?

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #9
Whatever your problem is, does not sound like caused by your amp.

Are you sure your CD is hooked up via RCA line out / line in while your Mac is hooked up via digital optical connection (rather than the other way around?)

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #10
Over short distances there is no advantage.  Over long distances the balanced (3-wire) connection is more immune to noise pickup.
Common mode noise rejection over long runs is the main advantage of balanced, but there is another secondary one: the ground planes of the source and receiver are separated, which will eliminate any ground loop issues. A ground loop can affect sound quality even if it's not so bad that it results in audible hum. It depends on the particular setup, of course, but sometimes balanced connections are worthwhile even over short runs.

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #11
Whatever your problem is, does not sound like caused by your amp.

Are you sure your CD is hooked up via RCA line out / line in while your Mac is hooked up via digital optical connection (rather than the other way around?)

Yep.  No question about it.

Now that I think about it.  If I'm running toslink from my Mac to my Onkyo receiver, doesn't that mean I'm using the DAC in the receiver and bypassing my Mac's DAC entirely?  I'm guessing a DAC in a $400 5.1 receiver (and $400 included the speakers) would be bottom of the barrel quality.

The only thing I haven't tried yet is disconnecting the Mac's toslink and connecting the Mac to the Onkyo via the headphone jack and RCAs.  That would violate one of the big rules I read about best possible connections in a computer based system, but I could give that a try to see if it eliminates the clipping. 


Quote
Common mode noise rejection over long runs is the main advantage of balanced, but there is another secondary one: the ground planes of the source and receiver are separated, which will eliminate any ground loop issues. A ground loop can affect sound quality even if it's not so bad that it results in audible hum. It depends on the particular setup, of course, but sometimes balanced connections are worthwhile even over short runs.

Would that result in clips or distortion triggered by an audio event like a sudden burst in singing or what-not?  You are referring to hum (or I assume any "constant" audio defect).  Would my symptom be resolved by balanced connections?  It seems like "unbalanced" problems are more pervasive and constant, aren't they?


Thank you both for the replies.

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #12
The only relief I found so far was to go into iTunes EQ and turn the iTunes preamp all the way to the bottom rung ... "-4" ... and then more than double the volume on my amp to almost 60 (out of 80).  That eliminates the clipping, but of course introduces some constant hiss from the loud volume on the amp.
Hi John, The above quote is a big clue. In iTunes, go under the iTunes menu:
ITunes>Preferences>Playback
and uncheck all three options. It is known that especially "Sound Enhancer" combined with the Equalizer "on" can cause clipping. I had this problem and unchecking the options fixed it.
Cheers, SAM

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #13
The only relief I found so far was to go into iTunes EQ and turn the iTunes preamp all the way to the bottom rung ... "-4" ... and then more than double the volume on my amp to almost 60 (out of 80).  That eliminates the clipping, but of course introduces some constant hiss from the loud volume on the amp.
Hi John, The above quote is a big clue. In iTunes, go under the iTunes menu:
ITunes>Preferences>Playback
and uncheck all three options. It is known that especially "Sound Enhancer" combined with the Equalizer "on" can cause clipping. I had this problem and unchecking the options fixed it.
Cheers, SAM

Your post had me so excited for a minute there, Sam.  I thought maybe you had found my solution for me.  But sad to report that I went to iTunes prefs just now and all three of those options were already unchecked by default. 

Dang.

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #14
Where's the volume setting of iTunes and system audio set to?

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #15
Where's the volume setting of iTunes and system audio set to?

Great question!

iTunes is set to a little less than 50%.

System audio is maxxed out to 100% by default when toslink is plugged in.  As far as I know, I can't change that.  (Of course, volume can be raised and lowered to the iMac speakers in the usual way if I unplug the toslink.)

It would make perfect sense for that to be the problem though, if it could be reduced.

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #16
Dang.
:-/
That would have been too easy, right?

But Joe Bloggs tip is good. Clearly the problem is in the Mac, since you can get rid of the clipping with the EQ preamp (but thereby lowering the overall output too much)

Look at the setting in the Output part of the Audio MIDI Setup app (/Applications/Utilities/Audio Midi Setup) and see whether there is a way to change levels for the TOSLINK or just try other settings.

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #17
Dang.
:-/
That would have been too easy, right?

But Joe Bloggs tip is good. Clearly the problem is in the Mac, since you can get rid of the clipping with the EQ preamp (but thereby lowering the overall output too much)

Look at the setting in the Output part of the Audio MIDI Setup app (/Applications/Utilities/Audio Midi Setup) and see whether there is a way to change levels for the TOSLINK or just try other settings.

Attached are screenshots of my system settings for audio.  You can see that output level can't be changed.  (At least not on that page.  I don't know of any other place where it could be.)

I looked at App/Util/Audio Midi Setup per your suggestion and included a screenshot of that, but don't see any changes I would want to make, unless I'm overlooking something.


Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #18
You might want to try another audio player program.

What's an audio player for Mac that shows a peak / clipping meter of the channels in real time?

Also, you might want to post a clip of these ripped CDs, just so we can check that the source file isn't itself clipping somehow.

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #19
You might want to try another audio player program.

What's an audio player for Mac that shows a peak / clipping meter of the channels in real time?

Also, you might want to post a clip of these ripped CDs, just so we can check that the source file isn't itself clipping somehow.

I'll have to see if one of my other players (which I never use) has a peak meter.

How do I post a clip of these ripped CDs so you can check that the source file isn't clipping?  That would be a 20+MB file if we were talking about a complete ALAC song, and I don't know how to edit down a song to, say, twenty seconds or so.

One of the CDs I am using is Diana Krall - Love Scenes.  Song: "All or nothing at all".  (Yes, the original commercial CD, not a bootleg.)  It's the one that is giving me the most conspicuous trouble with the clipping.

That album comes up on various lists of quality albums to use for giving systems an attentive listening, so I'm pretty sure the recording itself is not clipping.  I'm willing to assume that the same file would play perfectly on your system, no clipping.

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #20
I looked at App/Util/Audio Midi Setup per your suggestion and included a screenshot of that, but don't see any changes I would want to make, unless I'm overlooking something.

Try changing to 2ch-16bit integer and see what happens.

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #21
Maybe stating the obvious but a DAC is a Digital to Analog Converter.
If you use the Toslink out on the Mac, you are using a digital output hence; you bypass the DAC of the Mac completely.
If you want to hear what the DAC of the Mac is doing, get a stereo headphone jack to RCA cable and connect this to the amp.
A nice experiment is to switch between the Toslink and the headphone out.
The first tells you something about the DAC in the amp, the second about the DAC in the Mac.

Can’t make much sense out of your problem.
It is very common to have Toslink output set to 100% and do the volume control on the amp.
In general, rips are without errors.  I don’t expect it to be different from the CD unless some DSP like volume leveling has been used at rip time.
An option is to rip a couple CDs using XLD, just to make sure http://www.thewelltemperedcomputer.com/SW/OSX/Ripping.htm

Any setting on the amp affecting the Toslink input? (Bass boost etc)

You might try a spectrum analyzer like MusicScope https://www.xivero.com/blog/

It telles you if there is clipping in the ALAC
TheWellTemperedComputer.com

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #22
Roseval:  Yes, that's what I thought about bypassing the DAC.  I'm pretty green with digital audio, so what's obvious to you is just starting to make sense to me.  And yes, I ripped five CDs to do my close listening, not just the one.  The problem shows up all over the place.

SoundandMotion:  I'll try your suggestion in the morning.  It's 2:30am in my town and you helpful responders have kept me up way past my bedtime.  I can barely keep my eyes open, although strangely, I *hear* even more clearly in this state.

Joe Bloggs:  I opened the offending ALAC file in another free player I downloaded called Vox - supposedly popular with audiophiles.  There is no VU meter, but ... and we might have a breakthrough here ... there is no clipping whatsoever when I play the file in that program.  I can send full volume out and crank it up = clear as crystal.

I hope to still ultimately use iTunes because I love the thumbnail "Album-art View" system for organizing my CD rips.  (Vox just has crummy list views, like most other free music playback software for the Mac.)

But right at this moment, have we narrowed down the problem to a setting or a defect within iTunes?   :o


I'll be posting again in eight or ten hours.

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #23
There may be one more factor that appears to have been glossed over somewhat: The surround sound formats and what the receiver does with them.

But first, some background so that it makes sense for a layperson (hopefully).

In general, having a Toslink connection from computer to receiver is a good solution for several reasons:
  • Toslink being optical, there is no ground connection between computer and receiver, hence no ground loop. Hum shouldn't occur.
  • The data is sent digitally to the receiver, so the DAC in the computer isn't used, and its quality doesn't matter.
  • Through the same Toslink connection, you can send either an unencoded stereo signal (PCM), or an encoded surround signal.

Now, if you send a surround signal via Toslink to the receiver, the receiver will have to decode it. It needs a suitable built-in decoder for the format you are sending. Popular alternatives are Dolby Digital and DTS, but there are more. If the receiver doesn't have a suitable decoder, it should produce silence. You would also expect that the receiver has some sort of indication of the format it receives. This is important, as the format-specific processing done in the receiver has an impact on the sound.

If you use an external DAC instead, you will find that few of them have surround decoding abilities. The only thing you can send to the majority of them is an unencoded stereo signal. That's fine if stereo is all you want.

If the computer plays back a movie with surround sound, you usually want to pass the encoded audio signal unchanged to the receiver. The receiver would decode the signal, and apply any volume and bass management processing before converting it to analog and feeding it to the speakers. This means that the computer neither decodes nor otherwise processes the audio signal, it merely passes it on. In this arrangement, the sound quality depends on the receiver's internal processing, and on the speakers. The computer has no influence. However, you need to find software and software settings that make this happen. If any processing is to be done on the computer, even if it is only volume and/or EQ, the computer would have to decode the signal, apply the processing, and re-encode it for sending it across Toslink. There are licenses necessary to do that legally, and hence not all computers and/or software packages provide this possibility. I don't know the situation with your iTunes setup.

In principle, it can be the same with stereo, except that since stereo is unencoded, you can easily have processing on the computer side as well as on the receiver side, and since no encoding/decoding is necessary, there are no license restrictions.

Now back to your problem: Since receivers may apply their own processing, depending on the format they receive, you may want to check the settings of your receiver to make sure nothing is done to mess up your test. Try to make sure that the signal sent to the receiver is in PCM format, and that the receiver does not do any bass management or EQ processing of its own, but merely sends the two stereo channels to its L&R amplifier pair. Fiddling with the settings of AV receivers (and understanding what you are doing) can be a surprisingly frustrating experience. The signal path in the receiver is often poorly documented.

Similar things can be said of many computer playback applications. The signal path and the processing done in various places (App, OS, driver, soundcard) is often similarly obscure. You would want to simplify things as much as possible, and deactivate anything that's not essential.

Working from there, it will become easier to figure out what causes a signal impairment, for example due to clipping. A useful tool that you may want to get hold of is a sound file with sine wave signals at known amplitudes. Listening to it is boring, but distortion is audible very easily. This is much more useful for ferreting out signal path problems than using music signals.

Re: It's time for my first DAC and quality amp. Can anyone help?

Reply #24
Do you have the receiver properly configured to run those speakers full-range? By default, it probably assumes that a subwoofer is also connected, so you may not be hearing bass frequencies below ~120 Hz or so.

Also, does that cinema receiver allow you to auto-equalize with only two speakers connected? If so, I'd try that before spending more money. The fact that you get some relief by fiddling with the equalization in iTunes strongly suggests to me that frequency response of those speakers in your room is not very flat.