If you have a high end preAmp...do you still need a DAC?

[Geodesic1]

These questions could reasonably go in this forum topic or the server one...I picked this.

 

I have been struggling a bit with a server solution that I may have to return as it is somewhat buggy. I am considering a mac mini solution instead. I have a couple of questions...

 

1. Since the mac mini has an optical output, why wouldn't I simply connect it to my Cambridge Audio amp and let that amplifier act as the DAC? Am I missing something? Would an external DAC simply mean that it had to convert twice?

 

2. How does upsampling actually work? It sounds suspiciously like increasing pixel resolution on the wave form representation. Is that all it is (a smoothing)? Does it make a difference in sound? Or does it fill it with a new artifact?

 

3. Does anyone have experience pairing the mac with a touch screen?

 

Best regards,

 

R.

 

 

[souptin]

1. If your amp has an optical input then no problem, but not all amps do. Alternatively if you had a power amp or active speakers you might want to look at dacs (probably with volume control) and leave the preamp out of the chain. An external dac doesn't mean you'd convert twice since you would plug it into an analog input on your preamp.

 

2. That pretty much sums up what I think it does to the sound and why. Sometimes it sounds good, sometimes not so much. The big brains of this forum say there's some complicated filtering that goes on, often not user-controllable. Design compromises, swings and roundabouts and all that.

 

3. Only through using an ipod touch running vnc - it's cool, as are the various other remote control options, but I always come back to keyboard and mouse.

 

[Elprior]

Hi,

 

1. That means your Cambridge has an internal dac. With an external dac, you might have the double (in fact triple) conversion issue, if the analog inputs of the Cambridge do not pass-through the internal dac. This is typical of a/v electronics that do convert analog inputs using an adc before feeding the only available path that goes through the internal dac (denon/yamaha/...). Check the manual (if it ever mentions that), or email Cambridge.

 

2. No that has nothing to do with having a smoother signal, since the original signal can reconstruct the sound perfectly. This has to do with filtering in the dac, which is far easier at higher sampling rates. See post around here with a link to Dan Lavry papers (explaining the whole stuff).

 

hth,

Elp.

 

[Audio_ELF]

1) If your Cambridge Audio amp is an A/V type receiver then you can connect the optical digital output of the MacMini direct to the amp. Depending on the level of the amp, this will do anything from improve it a little, to improve it a lot - your only possible loss is the cost of a relevant cable. You won't have any issue of "double conversion". I think what you are referring to is where an AV amp converts analogue signals to digital before doing anything else with them. In fact using a digital connection into such an AV amp will avoid the double conversion. By using an external DAC (separate from the amplifier) you could potentially get even better sound quality, however this depends on the exact amplifier, etc you currently own.

 

2) Upsampling is designed to improve the audio quality. Some people agree, others disagree. Only by listening for yourself can you decide which camp you fit in. Its best to not really look at the specs of DACs, but to listen and buy the one that you like the sound of most and can afford.

 

3) I think Gordon at Wavelength did it ...

 

Eloise

 

PS. a few stereo amplifiers and pre-amps also have inbuilt DACs but this is an uncommon feature and none of the Cambridge Audio amps have digital inputs. The top end (740 and 840) CD players have digital inputs which work well.

 

[PeterSt]

Since the mac mini has an optical output, why wouldn't I simply connect it to my Cambridge Audio amp and let that amplifier act as the DAC? Am I missing something?

 

Let me have a somewhat different response here : Yes, you may be missing something.

If I'm way off, excuse me for a stupid post.

 

It looks like you think a "DAC" is everywhere, like in an amplifier. Well, it is not. D/A converters (Digital to Analogue converter, that's what it is) are in separate boxes, in the inside of CD players, or within the sound device of your PC.

Of course the D/A converter can be built into an amplifier, but this is verry uncommon.

What looks the most like what you suggest as how things are, would be a digital amplifier (which also takes digital for input which most do NOT do), but I guess this is not what you are talking about.

 

So, or you need to use the DAC which is inside the PC (that assumed) or you need to use an outboard DAC (with a thrid option of a soundcard with DAC to stuff into the PC).

 

If I am correct you didn't look at it like this, I estimate this answers your question about this ?

Peter

 

 

[Geodesic1]

Thanks for the information guys. Peter, you were right about my misconception. Thanks.

 

R

 

[bachrocks]

Something I saw recently mentioned in Stereophile, the Peachtree Audio Nova Tube Hybrid Integrated Amplifier. I thought it would be a good solution for my office at work. I guess you're not really looking for an amp but if you're curious about these rare creatures, here's one!

http://www.stereophile.com/thefifthelement/the_fifth_element_55/index1.html

 

And the company site:

http://www.signalpathint.com/index.php/Peachtree-Audio-Products/Peachtree-Audio-Products.html

 

And a review from 6moons site:

http://www.6moons.com/audioreviews/peachtree3/nova.html

 

I am not in anyway connected to this company or product.

 

cheers

 

[Geodesic1]

OK. I have some answers to my questions about DACs and I thought I'd post my own results for clarity.

 

1. The Cambridge Audio PreAmp DOES have an internal DAC. There are digital (coax and optical) inputs and analogue inputs. In the Cambridge Audio case, if you use the analogue inputs you bypass the internal DAC completely, and no processing is done on the sound. If you use the digital inputs, the sound is processed through the internal DAC. Conceiveably, you could connect your MacMini up to the Cambridge Audio amp and let it do the work. The server I am using (I have a new unit that appears to be working properly now...) also has a built in DAC, roughly equivalent to a high end CD player. Using that one rather than the Cambridge Audio DAC does produce a slightly different sound. The Cambridge Audio DAC produces a wider sound field, and it seems to produce greater frequency separation and crisper sound, however, the server has a rounder possibly more natural, if duller, feel? I haven't decided which one I will ultimately rely on and the problem is slightly more difficult because as soon as I switch from one to the other, there is a volume change. That aside, I am currently using the Cambridge Audio DAC.

 

I will probably not get an external DAC at this time.

 

Thanks for all your feedback!

 

[Audio_ELF]

With all due respect ... Cambridge Audio only make one pre-amp (the 840E) and this does NOT have a built in DAC.

 

I suspect what you have is one of Cambridge Audio's Home Cinema (Home Theatre) amplifiers. This will have a built in DAC as it is designed to work with digital signals and internally manipulates digital audio to create the 5(7).1 sound that you have with home cinema.

 

You say "the server [you are] using now also has a built in DAC roughly equivalent to a high end CD Player" I was interested in what device it was you had? Most computer sound cards, etc have "a built in DAC", but in most cases these can be improved upon with an external DAC.

 

Eloise

 

[Elprior]

Agreed with Eloise, although both DACs you are speaking of could be of good quality enough.

 

Since the analog inputs of your (presumably) a/v receiver do not go through the ad/da path, you could easily add an external dac with benefits.

 

Elp

 

[Geodesic1]

Right. I'm using an "AV Receiver" that is equipped for 6.1 surround. I'd forgotten that since I use it strictly for stereo music connected to a pair of focals.

 

I was reluctant to discuss the name of my server before sorting out difficulties with the first couple (physical models) that I had here, but I have all my music on an Olive Opus. It's working well and it's a fair bit more elegant than some of the other options (for my money anyway). The upfront work getting files organized internally was a pain...but now it's there and it sounds great!

 

I remain curious about the likelihood of hearing a difference using an external DAC and will probably audition the Cambridge Audio DACMagic to see how it compares. I've read some of the reviews and I gather that there are a few truly exceptional DACs, however, the costs are prohibitive. Particularly since I think I'm rapidly moving to the flat part of the curve where considerable effort produces small (if noticeable) improvements in sound. Comments welcome.

 

R

 

[Audio_ELF]

I've not personally heard the Olive Opus, but from things I've read I would think that the DAC inside it would be at least a similar level to the Cambridge Audio DAC Magic. I would think you'd be needing to spend on higher end equipment like Benchmark DAC 1 or Bryston BDA-1, etc to improve on it - however this is just my impression from reading about it so best thing would be (if possible) get hold of a Cambridge Audio DAC Magic and demo. We each have our limits of budget and want to get the best with what we can. If you're demoing the DAC Magic, it might also be worth trying to demo Stereo integrated amplifiers to replace the AV amplifier if you are not using the multi-channel functions - this MAY give you a bigger improvement for your money than a DAC replacement.

 

Eloise

 

[blueixus]

I have used some of the kit you mention. The Dacs in the Cambridge are really meant for AV/Home Cinema and will not be as good as those in the Olive, if you keep it. I also think you would need to spend quite a lot on a DAC to really outdo the Olive.

 

IF you change to a Mini Mac you WILL need a Dac as the Cambridge is, at best, not so strong on 2 channel music. I also tend to agree with Eloise that maybe if you are spending and don't need the 6 Channel capability of the Cambridge money spend on a decent 2ch integrated Amp would be the priority and keep the Olive. Assuming your speakers are OK, that is.

 

Regarding upsampling, many are suspicious, I think it can be good but needs very thorough implementation (meaning higher costs normally) and skill to make it work.

 

I have not tried a touch screen, it is on my to do list...

 

[Elprior]

The integrated amplifier might be a smart move, but then you are likely to spend money elsewhere, to match your new buy. If it sounds good to you, keep it that way.

 

Now, if you really want to discover the advantages of an external dac, go listen to a very expensive one, and find out for yourself if there is any gap. But then, be prepared for new buys, because your system in use is likely to become the limitation.

 

@blueixus

Regarding upsampling, go and read Dan Lavry's papers. You will find it hardly arguable that it benefits the sound. Whether you'd rather listen to a closer version of what is intended or a distorted one is then up to you.

 

Elp