DC-1

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Mar 20, 2014 14:14:53 GMT -5 KeithL said:

1) It could be that the USP-1 is more able to drive his particular load than the DC-1 (I doubt this one because the DC-1 shouldn't have trouble with most normal loads)
2) The extra gain provided by the USP-1 could be providing a signal that gets better performance out of the amplifier or the DAC (by adding gain, all the volume controls end up in different places, which could be resulting in lower noise or distortion somewhere)
3) It could be that the USP-1 is actually producing some small amount of distortion or frequency response variation that sounds nice (in his particular system)

Regarding 1), my preamp's input impedance is 47k ohm and the amps are 30k ohm.  These seem to be in the same ballpark to my untrained eye, meaning that if the DC-1 can drive one, it should be able to drive the other.

Regarding 2), at typical listening levels, would a preamp be adding gain with the DC-1 fixed output?  In variable direct mode, -8 dB is about as loud as I can listen. Listening at the same level using a separate preamp would be the result of an attenuation of the DC-1's 0 dB fixed output, right?  In other words, the preamp would not be providing gain.

Or, do preamps employ their full gain on an input, and then attenuate their gain with volume control?  If so, that could explain how a preamp could impact the sound.  The preamp's gain stage could impart its own sonic character, similar to how a DAC's output stage can impact the sound of a DAC.

With equipment I own, I see parallels to this. I have a MSB Nelson Link DAC (the most expensive DAC I own, based on retail price) which sounds overly aggressive in my system.  The best way I can describe this is that it makes me want to turn the volume down at high levels.  I'm also auditioning a Parasound 2100 preamp. My impression of the Parasound is very similar to the MSB Nelson Link DAC. Perhaps they are more "accurate" - I don't know, but they are less pleasing to my ears than other equipment I own.  I am really surprised that I do not find the Parasound 2100 to be an improvement over my "cheap" Cambridge Audio C500 preamp.

I can say that I also hear differences with the Cambridge and Parasound preamps with the DC-1 in fixed mode vs. the DC-1 direct.  With both preamps, the music sounds more forceful, daresay "dynamic". Bass impact and depth seems greater vs. DC-1 direct, the Parasound more so.  I don't know if this is due to the sound character of the preamps, or if they are playing more nicely with my amps vs. the DC-1 direct.  Currently, I prefer the Cambridge preamp with the DC-1.

Preferences and synergy are big parts of the equation, I feel.

[krusty]

Hi,

I am posting this on two threads just in case.

I’ve been experimenting noise coming out from my front speakers while on HT bypass mode while having the USB wire connected to my NAS and the DC-1, even with the DC-1 unplugged from the power supply. If I disconnect the USB end from the DC-1 the sound disappears.

I’ve got the DC-1 connected to the XPS-1 preamp through balanced connections, when playing music the sound is perfect, not interference but in HT bypass mode I can hear noise all day.

The XPS-1 is connected with the XPA-2 with balanced connectors also.

Just trying to hear if anyone has been experimenting these kind of noises.

Thanks.

[ouhkou]

Does DC-1 has a true preamp?

[garbulky]

Apr 20, 2014 2:25:21 GMT -5 ouhkou said:

Does DC-1 has a true preamp?

Yes it's a real pre-amplifier.

[garbulky]

Apr 17, 2014 8:45:50 GMT -5 krusty said:

Hi,

I am posting this on two threads just in case.

I’ve been experimenting noise coming out from my front speakers while on HT bypass mode while having the USB wire connected to my NAS and the DC-1, even with the DC-1 unplugged from the power supply. If I disconnect the USB end from the DC-1 the sound disappears.

I’ve got the DC-1 connected to the XPS-1 preamp through balanced connections, when playing music the sound is perfect, not interference but in HT bypass mode I can hear noise all day.

The XPS-1 is connected with the XPA-2 with balanced connectors also.

Just trying to hear if anyone has been experimenting these kind of noises.

Thanks.

You may need to get the DC-1 checked out. However it could also be a ground loop in your NAS. Try these three things
1. Before anything. Disconnect the DC-1 from the power for 30 seconds. Then plug it back in. Any difference?
2. Connect the NAS into the same power strip as the DC-1. See if that makes a difference.
3. Connect the USB to a laptop via USB without the laptop being plugged into the wall. See if it happens again
If these don't work you may need to send the DC-1 in in case there is some fault with the DC-1 USB connection.

[ouhkou]

Apr 20, 2014 2:45:28 GMT -5 garbulky said:

Apr 20, 2014 2:25:21 GMT -5 ouhkou said:

Does DC-1 has a true preamp?

Yes it's a real pre-amplifier.

It is NOT a Passive Attenuator Preamplifier ?

[audiobill]

That's right.

Active circuitry.

[garbulky]

Apr 20, 2014 5:24:12 GMT -5 ouhkou said:

Apr 20, 2014 2:45:28 GMT -5 garbulky said:

Yes it's a real pre-amplifier.

It is NOT a Passive Attenuator Preamplifier ?

Correct it's an electronic pre-amplifier using active circuitry. It uses a digitally controlled analog resistor ladder to change the volume. It can also be sort of used as an HT bypass to integrate with your multichannel AVR.

However....it is not a phono pre-amplifier. You need to have a phono pre-amp like the XPS-1 (not to be confused with XSP-1) to use a turntable with it. Unless your turntable has a phono pre-amplifier on it. If you don't know what I'm talking about (the turntable phono stuff), then chances are it doesn't apply to what you want to do and can be safely ignored.

[ouhkou]

Thanks for the confirmation.

Off course, I know what is a phono preamplifier for I have been using Turntable for decades.

[ouhkou]

Apr 20, 2014 5:53:18 GMT -5 audiobill said:

That's right.

Active circuitry.

Thanks

[krusty]

Apr 20, 2014 2:48:06 GMT -5 garbulky said:

Apr 17, 2014 8:45:50 GMT -5 krusty said:

Hi,

I am posting this on two threads just in case.

I’ve been experimenting noise coming out from my front speakers while on HT bypass mode while having the USB wire connected to my NAS and the DC-1, even with the DC-1 unplugged from the power supply. If I disconnect the USB end from the DC-1 the sound disappears.

I’ve got the DC-1 connected to the XPS-1 preamp through balanced connections, when playing music the sound is perfect, not interference but in HT bypass mode I can hear noise all day.

The XPS-1 is connected with the XPA-2 with balanced connectors also.

Just trying to hear if anyone has been experimenting these kind of noises.

Thanks.

You may need to get the DC-1 checked out. However it could also be a ground loop in your NAS. Try these three things
1. Before anything. Disconnect the DC-1 from the power for 30 seconds. Then plug it back in. Any difference?
2. Connect the NAS into the same power strip as the DC-1. See if that makes a difference.
3. Connect the USB to a laptop via USB without the laptop being plugged into the wall. See if it happens again
If these don't work you may need to send the DC-1 in in case there is some fault with the DC-1 USB connection.

Thank you garbulky

I've been able to isolate the problem and verified that the unit is not broken, it's a USB problem.

I connected the USB to my notebook through  a USB-HUB and the noise is no longer there.

Now that I am sure the USB ground or connection is the problem I'll try playing with the NAS also.

Emotiva Support also asked me to play around grounding all the devices together, which I'll try as well.

Thanks 

[ouhkou]

Is analog input = line amp? Are there any gain?

[GreenKiwi]

Analog input goes through the same analog volume control. So you can set it to 0 for no gain (or turn variable volume control off)

[anwklo]

Apr 20, 2014 23:40:23 GMT -5 GreenKiwi said:

Analog input goes through the same analog volume control. So you can set it to 0 for no gain (or turn variable volume control off)

Yes, how many gain in Db in variable mode?

[garbulky]

Apr 21, 2014 0:28:51 GMT -5 anwklo said:

Apr 20, 2014 23:40:23 GMT -5 GreenKiwi said:

Analog input goes through the same analog volume control. So you can set it to 0 for no gain (or turn variable volume control off)

Yes, how many gain in Db in variable mode?

I think it was 12 db? Also I'm not sure the meter was in db or not.

[ouhkou]

Apr 21, 2014 1:18:44 GMT -5 garbulky said:

Apr 21, 2014 0:28:51 GMT -5 anwklo said:

Yes, how many gain in Db in variable mode?

I think it was 12 db? Also I'm not sure the meter was in db or not.

12 db? I can't find any data at the Emotiva website and DC-1 manual.

[garbulky]

Apr 21, 2014 1:36:22 GMT -5 ouhkou said:

Apr 21, 2014 1:18:44 GMT -5 garbulky said:

I think it was 12 db? Also I'm not sure the meter was in db or not.

12 db? I can't find any data at the Emotiva website and DC-1 manual.

I may be wrong. If I recall the numbers on the display went upto 12 but I've slept since then. Also it may not be db.

[KeithL]

Mar 20, 2014 20:41:55 GMT -5 ads said:

Mar 20, 2014 14:14:53 GMT -5 KeithL said:

1) It could be that the USP-1 is more able to drive his particular load than the DC-1 (I doubt this one because the DC-1 shouldn't have trouble with most normal loads)
2) The extra gain provided by the USP-1 could be providing a signal that gets better performance out of the amplifier or the DAC (by adding gain, all the volume controls end up in different places, which could be resulting in lower noise or distortion somewhere)
3) It could be that the USP-1 is actually producing some small amount of distortion or frequency response variation that sounds nice (in his particular system)

Regarding

1), my preamp's input impedance is 47k ohm and the amps are 30k ohm.  These seem to be in the same ballpark to my untrained eye, meaning that if the DC-1 can drive one, it should be able to drive the other.

* Absolutely agreed; and the DC-1 should have no trouble driving loads down as low as 5k (or even lower), so that should NOT be an issue.

Regarding 2), at typical listening levels, would a preamp be adding gain with the DC-1 fixed output?  In variable direct mode, -8 dB is about as loud as I can listen. Listening at the same level using a separate preamp would be the result of an attenuation of the DC-1's 0 dB fixed output, right?  In other words, the preamp would not be providing gain.

* The basic design requirements for a good preamp are a high input impedance, a low output impedance, and some gain. Most really simple preamps pass the input signal through a selector switch, then a potentiometer volume control, than a fixed-gain "gain block". This basically meets all those requirements with the fewest parts. By using a fixed-gain gain block, you avoid all sorts of common ways in which the frequency response or distortion of a circuit may change as you vary the gain. (If you put the volume control after the gain block, then the volume control will raise the output impedance, so you need to add another buffer stage after it.) Some fancier designs use multiple gain stages and/or multi-stage volume controls; others may even vary the gain of the gain stage itself... and some may combine two or more of these methods. And, if you have tone controls or other processing, you're going to need at least a gain stage and a buffer stage. (However, there are other, "more interesting" ways of routing things - and they've all been tried at one time or another.)

* Regardless of the circuit topology, a preamp is generally intended to provide at least some gain at full volume... but how much that is, and at what point on the knob it adds gain rather than attenuation, is strictly up to the designer. The output level of the DC-1 is calibrated in dB, so the DC-1 should be applying a gain of 1 (which is 0 dB) when it is set that way. Also bear in mind that the signal is always going through the circuitry on the preamp - regardless of what gain is set. (If the preamp imparts some sound of its own, for whatever reasons, that change isn't going to NOT be there when the gain happens to be set to "1"; the signal is, after all, going through the same circuitry. Therefore, a preamp can impact the sound whether it is set to provide gain or attenuation.

Or, do preamps employ their full gain on an input, and then attenuate their gain with volume control?  If so, that could explain how a preamp could impact the sound.  The preamp's gain stage could impart its own sonic character, similar to how a DAC's output stage can impact the sound of a DAC.

With equipment I own, I see parallels to this. I have a MSB Nelson Link DAC (the most expensive DAC I own, based on retail price) which sounds overly aggressive in my system.  The best way I can describe this is that it makes me want to turn the volume down at high levels.  I'm also auditioning a Parasound 2100 preamp. My impression of the Parasound is very similar to the MSB Nelson Link DAC. Perhaps they are more "accurate" - I don't know, but they are less pleasing to my ears than other equipment I own.  I am really surprised that I do not find the Parasound 2100 to be an improvement over my "cheap" Cambridge Audio C500 preamp.

I can say that I also hear differences with the Cambridge and Parasound preamps with the DC-1 in fixed mode vs. the DC-1 direct.  With both preamps, the music sounds more forceful, daresay "dynamic". Bass impact and depth seems greater vs. DC-1 direct, the Parasound more so.  I don't know if this is due to the sound character of the preamps, or if they are playing more nicely with my amps vs. the DC-1 direct.  Currently, I prefer the Cambridge preamp with the DC-1.

Preferences and synergy are big parts of the equation, I feel.

* I'm inclined to suspect that the DC-1 is the most neutral, and the others are altering the sound in a way that you find pleasant. (In general, if ADDING a piece of equipment makes things sound differently, then that added piece of equipment is CHANGING something. While it's possible that the errors in two pieces of equipment would exactly cancel out, especially with frequency response anomalies, it isn't very likely with things like distortion.) Honestly, usually "differences in sound" can be traced to distortion or simple variations in frequency response. Often, devices that sound "punchier" simply have a slight bump in their frequency response, while those that sound "thin" have a slight dip. Even a fraction of a dB of difference "at a strategic frequency" can be noticeable. (And, often, slight changes that we don't notice as a difference in frequency response, can nevertheless be perceived as the sound being "heavier" or "deeper" or "clearer".) There are also some odder effects. For example, a higher level of background hiss can sometimes "sound" as if there's more "high end"; and reduced high-frequency distortion or noise sometimes seems like "less high end". Likewise, since we preceive higher levels of distortion as "louder", equipment that distorts more at high volume levels may be perceived as "more dynamic"... at least up until the point where the added distortion becomes annoying. (This is how "harmonic processors" and "harmonic exciters" like the Aphex Exciter work.)

[KeithL]

Yes.

The gain at 0 dB is 0 dB (1).
The setting goes up to +12 dB (at which point the gain is +12 dB)

Apr 21, 2014 1:36:22 GMT -5 ouhkou said:

Apr 21, 2014 1:18:44 GMT -5 garbulky said:

I think it was 12 db? Also I'm not sure the meter was in db or not.

12 db? I can't find any data at the Emotiva website and DC-1 manual.

[GreenKiwi]

I think that you should label it...

Our DC-1 goes to 11 + 1!