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Is this system likely to benefit from a separate DAC

kevinlar

Standard Member
I have a Marantz PM6003 amp powering a pair of wharfedale diamond 9.1's. I usually use my laptop, xbox or Ipod touch as a source. Would I be able to hear any significant difference in the sound if I bought a cheap DAC like the
Behringer U-CONTROL UCA202?
 

larkone

Distinguished Member
Yes - just about any offboard sound card is better than on board
 

PicoB

Established Member
Hard to say. Onboard DACs are not as poor as most people think. Signal to noise ratio of greater than 98 dB and proper internal shielding from EMI is what makes a good DAC. Other than that, there is no difference in software/algorithm that instructs the circuitry to convert from digital to analog.

In your case. It would be wise to know the return policy of the DAC you are considering to purchase then decide if it is worth the extra cost to you.
 
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larkone

Distinguished Member
Onboard DACs are not as poor as most people think. Signal to noise ratio of greater than 98 dB and proper internal shielding from EMI is what makes a good DAC.

We are talking laptop here, not a PC with a quality soundcard
 

CJROSS

Prominent Member
For £20 it will also add the ability to add a Toslink output to your laptop, I find this great for taking my laptop up to my digital amps and sending Spotify to them.
 

scorpion88

Established Member
I usually use my laptop, xbox or Ipod touch as a source. Would I be able to hear any significant difference in the sound if I bought a cheap DAC like the
Behringer U-CONTROL UCA202?

The SQ from my iPod Touch and PC is very poor compared to that from my CDP. IMO £20 is a small price to pay for what I expect would be a tangible increase in SQ.

There is no doubt that an iPod and PC for that matter is a convenient way of playing music if the SQ can be improved.
 

Gixxerblade

Established Member
The SQ from my iPod Touch and PC is very poor compared to that from my CDP. IMO £20 is a small price to pay for what I expect would be a tangible increase in SQ.

There is no doubt that an iPod and PC for that matter is a convenient way of playing music if the SQ can be improved.

How do you send the sound from your PC i.e. what output method and what software program and operating system?
 
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scorpion88

Established Member
How do you send the sound from your PC i.e. what output method and what software program and operating system?

Not sure what software programme exactly - computer quite old. I do know it is an AMD Athlon 64 X2 Dual Core (if that helps):D

Output is single RCA Jack from front of Computer to Aux RCA on amp. Not sure what sound card in Computer.

I seem to recall when purchased some 6 years or so ago that it supports HD Audio but this is certainly not what I'm receiving. Perhaps I need a new machine:rolleyes: - although it works well for all other applications.

As you can tell - not really a Computer boffin.:laugh:

Cheers
 

dogfonos

Prominent Member
Kevinlar - I'm not familiar with your sources, but on a practical note, do you currently feed analogue outputs from the three sources into three different inputs on the amp and use the amp's input selectors to switch between the three (i.e. are the three sources permanently connected to the amp)?

Reason I ask is because the Behringer DAC you mention may not accept all three sources at once and provide the necessary switching between them. On the other hand, if you currently plug/unplug your sources then you may still need to do so with the Behringer.
 

kevinlar

Standard Member
I currently plug and unplug them. I think I may leave my xbox plugged in without the DAC, I would have thought that the internal DAC on that is probably better than the one in my ipod or the one in my laptop... could be mistaken though! If I were to make use of an external DAC for my xbox, I would prefer to have an optical input to be honest, That is the connection I use for my astro mixamp and headset when I use that.
 

dogfonos

Prominent Member
I currently plug and unplug them. I think I may leave my xbox plugged in without the DAC, I would have thought that the internal DAC on that is probably better than the one in my ipod or the one in my laptop....

Although I've no experience of this, I've heard exactly that said on these forums in the past.

It's also been said on this forum and others that, for the best sound quality, feed the USB connection from your PC/laptop into an external DAC - something to do with the USB connection allowing the external DAC to manage timings of the digital signal instead of the PC/laptop (an external DAC usually does a better job, evidentally). Other digital connections (i.e. SPDIF) rely on the source for timings, I believe. I don't pretend to understand this stuff myself.

Could you do a 'sound-off' between the xbox and the laptop using the same CD to see which gives best audio? Whichever looses has the worst internal DAC.
 

kevinlar

Standard Member
Could you do a 'sound-off' between the xbox and the laptop using the same CD to see which gives best audio? Whichever looses has the worst internal DAC.

I think I will do exactly that when I get back in tomorrow night!

I have actually just purchased the previously mentioned Behringer DAC from ebay, It should arrive within 5 or so days, I'll post here if it provides any noticable improvement! I'm also thinking about buying some QED profile interconnects, as this will undoubtly improve on the utter crap that I'm using now. (they are terminated with a metal case thingy, this STINGS TO THE TOUCH WHEN MY AMP IS ON. I purchased this in PC world! no idea what's going on there but it can't be good!
 
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juggler

Established Member
kevinlar said:
this STINGS TO THE TOUCH WHEN MY AMP IS ON. I purchased this in PC world! no idea what's going on there but it can't be good!

Then your amp has a problem and is potentially lethal. Plus, it may fry your new DAC. It can't just be the cable.

It might be a trivial fix, it might not.
 

kevinlar

Standard Member
Then your amp has a problem and is potentially lethal. Plus, it may fry your new DAC. It can't just be the cable.

It might be a trivial fix, it might not.

I put this down to the cable not being insulated correctly :/ I wrapped the metal casing in insulation tape, there doesn't seem to be a problem anywhere else... I sincerely doubt that it could be lethal, the sting can't even be felt with the fingertips, I need to touch it with my arm to feel it. I've ordered some new rca cables, I'll see if that resolves the problem. Personally, I think it will sort everything out.
 

juggler

Established Member
kevinlar said:
I put this down to the cable not being insulated correctly :/ I wrapped the metal casing in insulation tape

Whether the cable is insulated or not the voltages and currents involved shouldn't be enough to give you a shock.. Your use of block capitals suggested that the problem was a significant one.

It still sounds like an earthing fault in the amp to me, but others may disagree. I am not an electronics engineer but the only times I've ever had any kind of shock has been either static, my stupidity or a fault.

Insulating the cable may help but in general equipment is designed so that it takes at least two faults before something shocking or dangerous can occur. Perhaps a failure of insulation is exposing another problem?
 

kevinlar

Standard Member
Whether the cable is insulated or not the voltages and currents involved shouldn't be enough to give you a shock.. Your use of block capitals suggested that the problem was a significant one.

It still sounds like an earthing fault in the amp to me, but others may disagree. I am not an electronics engineer but the only times I've ever had any kind of shock has been either static, my stupidity or a fault.

Insulating the cable may help but in general equipment is designed so that it takes at least two faults before something shocking or dangerous can occur. Perhaps a failure of insulation is exposing another problem?

it isn't a shock at all, just stings constantly. The caps were just because it seemed like such an odd thing to happen. I don't really know what to do with it, if the new cables don't resolve the issue, I'll start to think about that.
 

dogfonos

Prominent Member
it isn't a shock at all, just stings constantly.

Really, it almost certainly is an electric shock. Whilst it probably is static electricity rather than mains electricity that's causing this, you should get to the bottom of it for your own safety.

Couple of years ago I encountered a similar problem. When I touched the rear metal panel of a cheap CD/DVD player, I received an electric shock. Turns out this was caused by a static build up on the player - no surprise when you think about it, a spinning plastic disc nestled in a predominantly plastic case. The player didn't have a mains earth (many don't) so earthed through the interconnecting lead. When the interconnecting lead was connected, I didn't get a shock because the static drained away through the outer sheathing cable into the active speakers it was connected to (which had a mains earth connection).

In your case, you still get a shock even though the player is connected to your amp. Hmmm. Does your amp have a mains earth? If so, perhaps your interconnecting cable is as bad as you suggest and the outer sheath cable is not continuous (i.e. it's broken).
 

juggler

Established Member
It's unlikely to be static if it is constant and not discharged by a touch.
 

dogfonos

Prominent Member
It's unlikely to be static if it is constant and not discharged by a touch.

Maybe, maybe not. Static is not always predictable. A static charge could build quickly again following a momentary discharge, such as in this case, if a disc continues to spin in the player. But I'm no expert, I just worked in an industry where we had to take precautions against it.

What does this mean for the amp? Is that a serious problem?

If it's a mains electrical issue then it's as much a serious problem for the amp as it is for you or anyone in the vicinity.
If it's static, then I suspect your speakers could be vulnerable but I wouldn't expect amp to suffer damage. That's just a best guess though.
 

kevinlar

Standard Member
It's more of a 'tingle' than a sting now that I think about it. The amp casing also provides a strange sensation when I run my finger along it (can't feel this at all without the movement) I can feel a slight buzzing or a vibration. I thought it was odd at the time, but just assumed it was normal since this is my first amp and speaker setup :/
 

juggler

Established Member
A static charge could build quickly again following a momentary discharge

True - though I was struggling to think of a mechanism by which this might occur in a solid state amp.

kevinlar, I think you need to get in touch with someone who really know what they are talking about; all that we're really qualified to say here is that something is wrong and that that something may be dangerous.

Here's a very similar problem with the same amp:
http://www.avforums.com/forums/hi-f...416334-static-kickback-when-touching-amp.html

From the last post in that thread:
Safety Warning: I don't wish to scaremonger but, if the amp is `earthy' the engineers term for earth faults, it could be lethal if the amp is switched on and not earthed through another component such as a cdp, this is normally acheived via the screened phono connecting cable, but again must not be relied on 100%.

i.e. The only reason it is currently safe may be because it is connected to another device which is earthed, via your interconnects. Disconnect them and leave the amp turned on and it might get a whole lot more dangerous.
 

kevinlar

Standard Member
Since I reconnected the amp to my xbox, all of these problems seem to have disappeared (could also be that I've changed the mains plug it's in I guess) The Marantz PM6003 is double insulated and has no earth in the cable, I assume it's not earthing through the xbox's earth. Since this seems to require such specific conditions to have a small chance of actually being dangerous, I think I'll leave it untill I've gone on holiday to do anything about. I WILL make sure everything is safe after that though. I'm inclined to believe that it most likely is all safe anyway, I've never recieved a 'proper' static shock, just this mild tingling sensation.
 

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