[Shadorne]

Quote:

Originally Posted by G-U-E-S-T /img/forum/go_quote.gif Hi Elias, I read your online post regarding the use of the DAC1 directly connected to the amp, where you advise the following: Quote from Elias Gwinn: "Avoid using amplifiers that are too powerful for your system! You'll get best results when using 75-95% of the amps total power." I always thought it was better to have more clean amp power on tap to properly handle musical transient peaks, similar to what Musical Fidelity advises at this link (also note their interesting "System Diagnostic" link on that page). I have been using a powerful (255W @ 8-ohm) Musical Fidelity stereo amplifier with some very nice 7-ohm minimum bookshelf speakers. After reading your quote above, I'm now wondering if my amp is "too powerful" and whether optimally I should change this. Please advise? Thanks again, in advance.

Actually I think there is not a single simple answer here. Ratings of speakers are very subjective anyway. Many speakers with high ratings are simply designed to compress (long voice coil in short gap) - sure they can handle huge amounts of power without breaking but they quickly sound dull as the voice coil heats up and often these designs have a smaller Xmax - so you are just listening to distortion anyway.

Practically speaking you generally need a coupe of hundred watts for each large high quality woofer (12" +). A midrange can often use no more than 50 to 100 watts. While a tweeter you may be fine with a mere 10 watts. Practically speaking, for "best" you might want to go Class D amps with several large woofers for the bass whilst it would be "best" to run your tweeter and mids on a good Class A - or for those who like warmth you could simply add tubes.

This is why Active speakers are so attractive - you get the Hanna Montana experience - the "best of both worlds" - great bass that even when over-driven does so without adding distortion to the mids and highs...

(We can all put up with some distortion in the bass but distortion in the mids and highs is AWFUL, nails on blackboard)

 

[EliasGwinn]

Quote:

Originally Posted by gevorg /img/forum/go_quote.gif What if your amplifier has gain controls, will that help to improve dynamic range? Or its the same as attenuating at the source? For example, say a low-impedance and high sensitivity headphones are too loud at 20% of maximum volume of a given powerful amplifier. Then you reduce the gain inside amplifier so that the maximum listenable volume increases to around 50% of maximum volume. At the same volume level, will the dynamic range improve?

It's hard to say because amplifiers have very different implementations of 'gain control'. Sometimes its simply input attenuators.

Can you describe your proposed setup more specifically, including model numbers?

All the best,
Elias

 

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[yilmaz196]

Hi Elias, i just bought usb dac1. I have a question. Even when i am not listening to it, it is still hot. There is no on-off button so i am switching to another input(i use usb input for listening) to standby mode. But like i said it is still hot. No lights but always hot. Is this normal, this dac never off i think.

 

[EliasGwinn]

Quote:

Originally Posted by yilmaz196 /img/forum/go_quote.gif Hi Elias, i just bought usb dac1. I have a question. Even when i am not listening to it, it is still hot. There is no on-off button so i am switching to another input(i use usb input for listening) to standby mode. But like i said it is still hot. No lights but always hot. Is this normal, this dac never off i think.

This is normal. When the DAC1 USB is in 'Standby' mode, all electronics are still powered. Therefore, the temperature of the unit will not change. This won't affect the performance of the DAC1 USB, nor will it shorten the life-span. It is not a problem.

All the best,
Elias

 

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[G-U-E-S-T]

Quote:

Originally Posted by EliasGwinn /img/forum/go_quote.gif I agree with them, for the most part. I'll clarify my statement: It is best to have an amplifier whose input peaks at the same level as the maximum output level of the source (e.g., DAC, PRE), and this amplifier/speaker combination should only be "loud" enough so that maximum comfortable listening levels are acheived near peak input (transient peaks reach full-scale). In other words, it is ideal to use ALL of your headroom without going over. The reason for this is to acheive the best possible dynamic range. If you must attenuate the source to prevent the amplifier/speakers from becoming too loud for comfort, then you are losing dynamic range. The amount of dynamic range you are losing is equivelant to the amount of attenuation you are employing. The reason is that the amplifier has a specified noise floor. This noise doesn't attenuate when the source is attenuated. So, when the source is attenuated, the result is lower signal-to-noise ratio. In a high-precision playback system, amplifiers are typically the limiting factor in dynamic range. If your amp is too powerful for your typical listening levels, you will attenuate your source and decrease your dynamic range even further. Does this make sense to you? All the best, Elias

Hi Elias,

Thank you very much for your reply, and sorry about the delay in responding. I *think* that I understand what you are explaining - but I just don't personally know how this could, practically speaking, be achieved (?)

For instance, my bookshelf speakers are 7-ohm minimum, and I never drive them to really high levels. My current stereo amp gives 255 watts (way more than I probably need) into 8 ohms, from 1.5v input, with <0.01% THD (20Hz - 20KHz) and >109dB SNR.

But it is typical of my sources to provide what I believe is very significantly more than 1.5 volts peak output! For example:

1) My DAC1-Pre "variable" RCA output reaches up to 11dBu (which I think is about 2.75v rms, 7.8v peak-to-peak), with <0.00056% THD and 116dB SNR.

2) Another of my sources (a SqueezeBox Classic) on its RCA outputs gives about 2.1v rms (6.0v peak-to-peak), with <0.002% THD and >100dB SNR.

So if I didn't attenuate these sources, I would probably go deaf in a matter of moments! It seems if I understand your advice correctly, that I would need to find an amp that has an input sensitivity of almost 3v -- and even then, only outputting a small number (maybe 50 or 75?) of watts, to power my bookshelf speakers. Is such an amp out there?

Also, if I do recall correctly: I think you previously recommended getting things set up to where the DAC1 volume level is comfortable within around the 10 o'clock to 2 o'clock range. So since this range is (obviously) far from full volume, wouldn't this also be less than ideal as well, as per your advice above?

Very sorry if these are "dumb" questions, but I really am trying to understand!

[Edit: Typo - changed the "116dB THD" to "116dB SNR"]

 

[Quaddy]

elias, would appreciate some backup here, have the dac1 pre and am using one set of headphones with it only, the sennheiser hd800 which has a impedance rating of 300ohm

with regard to headphone gain adjustment would the unit be best at position A, B, or removed

to be honest i cant remember what position they are at now, or if they are removed, i will look soon

i appreciate this all depends on setup, but on paper is there anything which shouts to you that would maybe be better matched on paper with the gain range for 300ohm

thanks!

edit: well i went through the options and had a good listen at each change, to my ears, the hd800 sounds a lot more driven and powered correctly with the headphone gain jumpers removed, not at -10db or -20db - in fact i am suprised at how anemic they sounded with anything other than removed for max gain. guess i answered my own question there anyway

 

[EliasGwinn]

Quote:

Originally Posted by G-U-E-S-T /img/forum/go_quote.gif Hi Elias, Thank you very much for your reply, and sorry about the delay in responding. I *think* that I understand what you are explaining - but I just don't personally know how this could, practically speaking, be achieved (?) For instance, my bookshelf speakers are 7-ohm minimum, and I never drive them to really high levels. My current stereo amp gives 255 watts (way more than I probably need) into 8 ohms, from 1.5v input, with <0.01% THD (20Hz - 20KHz) and >109dB SNR. But it is typical of my sources to provide what I believe is very significantly more than 1.5 volts peak output! For example: 1) My DAC1-Pre "variable" RCA output reaches up to 11dBu (which I think is about 2.75v rms, 7.8v peak-to-peak), with <0.00056% THD and 116dB THD. 2) Another of my sources (a SqueezeBox Classic) on its RCA outputs gives about 2.1v rms (6.0v peak-to-peak), with <0.002% THD and >100dB SNR. So if I didn't attenuate these sources, I would probably go deaf in a matter of moments! It seems if I understand your advice correctly, that I would need to find an amp that has an input sensitivity of almost 3v -- and even then, only outputting a small number (maybe 50 or 75?) of watts, to power my bookshelf speakers. Is such an amp out there? Also, if I do recall correctly: I think you previously recommended getting things set up to where the DAC1 volume level is comfortable within around the 10 o'clock to 2 o'clock range. So since this range is (obviously) far from full volume, wouldn't this also be less than ideal as well, as per your advice above? Very sorry if these are "dumb" questions, but I really am trying to understand!

They're not dumb questions! I'm happy to explain.

Tell me this... You use the RCA outputs of the DAC1 to directly drive your amplifier, correct? Where do you normally have the volume control set?

 

[EliasGwinn]

Quote:

Originally Posted by Quaddy /img/forum/go_quote.gif elias, would appreciate some backup here, have the dac1 pre and am using one set of headphones with it only, the sennheiser hd800 which has a impedance rating of 300ohm with regard to headphone gain adjustment would the unit be best at position A, B, or removed to be honest i cant remember what position they are at now, or if they are removed, i will look soon i appreciate this all depends on setup, but on paper is there anything which shouts to you that would maybe be better matched on paper with the gain range for 300ohm thanks! edit: well i went through the options and had a good listen at each change, to my ears, the hd800 sounds a lot more driven and powered correctly with the headphone gain jumpers removed, not at -10db or -20db - in fact i am suprised at how anemic they sounded with anything other than removed for max gain. guess i answered my own question there anyway

I use the HD650's, which are also 300 ohm. I keep the HPA2 gain range in the -10 dB position (the 'A' position).

The optimal setting is whatever allows you to use the volume control in the 'sweet spot' (10 o'clock - 3 o'clock). If this range is too loud, decrease the gain range jumper setting. If this range is not loud enough, reduce the gain range setting.

All the best,
Elias

 

[G-U-E-S-T]

Quote:

Originally Posted by EliasGwinn /img/forum/go_quote.gif They're not dumb questions! I'm happy to explain. Tell me this... You use the RCA outputs of the DAC1 to directly drive your amplifier, correct? Where do you normally have the volume control set?

When using the RCA outputs, and for our "regular" daily listening: I think we probably keep the volume dial between around 8 o'clock and 11 o'clock on average. We hardly ever try to rock the house down!

P.S. I also just noted from the manual, that in variable mode, the DAC1 volume control attenuates the signal until the dial reaches around 3 o'clock (the 30th detent or so), at which point 0dB attenuation is reached (per the manual graph).

 

[EliasGwinn]

Quote:

Originally Posted by G-U-E-S-T /img/forum/go_quote.gif When using the RCA outputs, and for our "regular" daily listening: I think we probably keep the volume dial between around 8 o'clock and 11 o'clock on average. We hardly ever try to rock the house down! P.S. I also just noted from the manual, that in variable mode, the DAC1 volume control attenuates the signal until the dial reaches around 3 o'clock (the 30th detent or so), at which point 0dB attenuation is reached (per the manual graph).

So, in your case, the output from the DAC1 is around 0.25 V. This is a very small percentage of your amplifier's operating range.

Your amplifier's input circuitry will have a certain noise level, which is also amplified along with the input signal. The more powerful the amp, the louder the noise AND signal gets amplified.

So, in your case, you've got a small signal and a (relatively) large noise. Consequently, your signal-to-noise ratio is suffering.

If your amplifier had a lower gain ratio (less power), you could increase the signal and decrease the noise. Consequently, you would improve your signal to noise ratio.

Now, with that said, it is true that you want to have ample headroom, but as you can see here, too much headroom is detrimental as well. Ideally, the output of the DAC1 would peak just below the maximum input level of the amplifier without it becoming too loud for your listening comfort.

All the best,
Elias

 

[G-U-E-S-T]

Quote:

Originally Posted by EliasGwinn /img/forum/go_quote.gif So, in your case, the output from the DAC1 is around 0.25 V. This is a very small percentage of your amplifier's operating range. Your amplifier's input circuitry will have a certain noise level, which is also amplified along with the input signal. The more powerful the amp, the louder the noise AND signal gets amplified. So, in your case, you've got a small signal and a (relatively) large noise. Consequently, your signal-to-noise ratio is suffering. If your amplifier had a lower gain ratio (less power), you could increase the signal and decrease the noise. Consequently, you would improve your signal to noise ratio. Now, with that said, it is true that you want to have ample headroom, but as you can see here, too much headroom is detrimental as well. Ideally, the output of the DAC1 would peak just below the maximum input level of the amplifier without it becoming too loud for your listening comfort. All the best, Elias

Thanks very much for this very interesting SNR information Elias. As you probably know, this is not an aspect usually mentioned, as the gospel-dogma for most audiophile-oriented consumer buyers (and dealers!) is to always buy as many extremely-clean watts as you can afford - and that is in fact how my dealer sold me a (apparently WAY over-powered) $3000 stereo amp to accompany our really nice bookshelf speakers. And honestly, it really does sound extremely good just as it is! On your advice though, I will now begin looking for a new (and much lower powered) stereo amp that is more appropriate for my system. If I understand you correctly, for us this should ideally be a stereo amp with only approx. 50 watts of power, and requiring approx. 3-volts of input signal to actually reach that full 50 watts. Is that about correct?

I'm embarassed to admit this, but so far in my rather careful initial search for such an amp, I cannot seem to find anything that properly fits those parameters as I believe you've described for me. Can you perhaps please, suggest any stereo amps that would be good choices for us to try?

Also, is there a general formula available that you could please share, for calculating both the nominal voltage and the peak voltage that the DAC1 outputs at various detents (or perhaps at the approx. clock-hour positions) on it's volume dial? That would be *so* helpful to have, so that DAC1 users could try to find amps with input sensitivities that properly match their usual source signal voltages. I'm also not certain if the 0.25-volt value you mentioned in your last post, represents nominal output, or peak output (?)

Thanks again in advance Elias - I think this info will help a lot of people!

 

[wavoman]

Help with the trim pots, pretty please!

Well I see by searching this thread -- a little too late, I'm afriad -- that I should not have screwed with the trimmers.

Before I opened up the box and moved the jumper to 0, solving my balanced output volume problem, I used a small screwdriver to turn the trimmers.

But the trimmers don't seem to have ANY mechanical stops on either side!

I see I am supposed to have test tones and meters -- but I don't.

All I want to do now is get L and R at the same level -- but how do I know where the trimmers are? I turn and turn and turn and never hit a stop in either direction ... did WAY MORE than 10 turns!

Any help would be appreciated. For now I have moved the toggle to VARIABLE to take the trimmers out of play, but I don't want to leave it there ... I wanted fixed (calibrated) output to my amp for speakers, and wanted to use the volume control only for headphones!

Elias, Help !! ?? Am I crazy -- is there a mechanical stop and I just gave up?

THANKS!

 

[synfreak]

Hi Wavoman!

Do you own a (good quality) "soundcard/audiointerface" and some dedicated software (i.e. audacity)?

you then might be able to use the meters in the software to adjust the analogue levels of your DAC1.

This might not be 100% perfect (as it would be with a multimeter and the replay of a sinus signal), but it should be within about 0,5db (depends on the precission of the software meter).

Cheers
Harald