NAD vs NAD

[Squishy Mittens]

I have been using an NAD C388 since they first came out. Been powering a pair of PSB Imagine T2's. Ran that set up for about a year, was quite pleased. No complaints. But I wanted to experiment, as you do with this hobby, and bought a C275 to bi-amp the speakers. Holy moly the 275 blows the 388 out of the water. I didn't realize these speakers could put out the bass that they do. I first thought, maybe it's because I'm bi-amping. But no, the 275 on its own is just immensely powerful. Both amps are rated at 150wpc and both are NAD. There is such a difference, though, I almost was suspecting something was wrong with the 388. Am I missing something? Or is Class D and Class AB just that different?

 

[lovinthehd]

Have no idea what blows out of the water translates to. Do they have the same sensitivity rating?

 

[Squishy Mittens]

Have no idea what blows out of the water translates to. Do they have the same sensitivity rating?

How do I look that up? And by blow away I mean my speakers actually put out bass now. With the 388 the bass was...ok. Not terrible, not great. With the 275 the speakers put out so much bass that I actually turned down the tone control, which I've never done. It's not just the bass, mids and highs seem fuller.

 

[lovinthehd]

How do I look that up? And by blow away I mean my speakers actually put out bass now. With the 388 the bass was...ok. Not terrible, not great. With the 275 the speakers put out so much bass that I actually turned down the tone control, which I've never done. It's not just the bass, mids and highs seem fuller.

Dunno. Sounds like a level difference. Assuming the same input, the amps may have different sensitivity levels which translate to level differences. The spec is called sensitivity and usually expressed in terms of volts (typically in the range of 1 to 2 volts). Did you look up the specs of each amp or check their manuals? Should be there somewhere. If the amps are rated for similar output I'd guess that's where the differenc lies....

 

[Squishy Mittens]

Dunno. Sounds like a level difference. Assuming the same input, the amps may have different sensitivity levels which translate to level differences. The spec is called sensitivity and usually expressed in terms of volts (typically in the range of 1 to 2 volts). Did you look up the specs of each amp or check their manuals? Should be there somewhere. If the amps are rated for similar output I'd guess that's where the differenc lies....

I will take a look. Thank you!

 

[lovinthehd]

Or perhaps if your pre-amp output is adjustable try that as well.

 

[PENG]

Dunno. Sounds like a level difference. Assuming the same input, the amps may have different sensitivity levels which translate to level differences. The spec is called sensitivity and usually expressed in terms of volts (typically in the range of 1 to 2 volts). Did you look up the specs of each amp or check their manuals? Should be there somewhere. If the amps are rated for similar output I'd guess that's where the differenc lies....

I compared the specs, and found:

C275 - Gain: 29 dB (that is about 1.23 V for 150 W 8 ohm based on my calculations)
C388 - Input sensitivity for line in to speaker out: 490 mV to give 80 W into 8 ohm, volume at maximum

My calculations show that the C388 will give the rated output of 150 W into 8 ohm with just 0.668 V input, that translates into a relatively high gain of 34.3 dB.

I think your point about level difference is valid regardless. Although the C388 has a higher gain, it is still possible that it is a volume matching issue if the OP did not use a SPL meter and a test tone. That's because those two amps may have totally different volume control characteristics. The C388 may still have to be turn higher up in order to match the output of the C275, but of course I am not speculating. The thing is, based on NAD's own published specs, there is no way the C275 could "blow the C388 out of the water". If the OP level matched the two to within 0.5 dB, I doubt he could tell those two amps apart.

 

[Squishy Mittens]

I compared the specs, and found:

C275 - Gain: 29 dB (that is about 1.23 V for 150 W 8 ohm based on my calculations)
C388 - Input sensitivity for line in to speaker out: 490 mV to give 80 W into 8 ohm, volume at maximum

My calculations show that the C388 will give the rated output of 150 W into 8 ohm with just 0.668 V input, that translates into a relatively high gain of 34.3 dB.

I think your point about level difference is valid regardless. Although the C388 has a higher gain, it is still possible that it is a volume matching issue if the OP did not use a SPL meter and a test tone. That's because those two amps may have totally different volume control characteristics. The C388 may still have to be turn higher up in order to match the output of the C275, but of course I am not speculating. The thing is, based on NAD's own published specs, there is no way the C275 could "blow the C388 out of the water". If the OP level matched the two to within 0.5 dB, I doubt he could tell those two amps apart.

Thanks for the input! I'm sure I'm just not setting something up correctly. It's just strange to me that running one amp versus the other yields such different results at the same volume. You mention level matching, is that when using both amps in bi-amp mode?

 

[PENG]

Thanks for the input! I'm sure I'm just not setting something up correctly. It's just strange to me that running one amp versus the other yields such different results at the same volume. You mention level matching, is that when using both amps in bi-amp mode?

Nothing to do with biamp. Level matching means making sure the two amplifiers being compared for sound quality are producing the same sound pressure level at your listening position. You cannot just go by the volume dial positions. If you don't level match them before you do your comparison, the louder one is going to sound better (especially in the low end and higher end of the frequency spectrum) if both amplifiers are operating within their comfortable range.

 

[lovinthehd]

Thanks for the input! I'm sure I'm just not setting something up correctly. It's just strange to me that running one amp versus the other yields such different results at the same volume. You mention level matching, is that when using both amps in bi-amp mode?

Well, that's the key...how did you determine they are at "the same volume" in your current comparison? For some reason I thought with the similar model names and your description they were both power amps but that's not the case now that I look (C275 is a power amp whereas the C388 is an integrated).

Have you read this article before? http://www.audioholics.com/frequent-questions/the-difference-between-biamping-vs-biwiring

 

[Squishy Mittens]

Well, that's the key...how did you determine they are at "the same volume" in your current comparison? For some reason I thought with the similar model names and your description they were both power amps but that's not the case now that I look (C275 is a power amp whereas the C388 is an integrated).

Have you read this article before? http://www.audioholics.com/frequent-questions/the-difference-between-biamping-vs-biwiring

I have not read the article but I will, thank you. And by same volume I just mean setting it to what sounds like "normal" to me when I'm listening to music. Not loud by any means. In order to get the 388 to put out the same bass level as the 275 i needed to turn it up quite loud, louder than I would enjoy listening to.

 

[lovinthehd]

I have not read the article but I will, thank you. And by same volume I just mean setting it to what sounds like "normal" to me when I'm listening to music. Not loud by any means. In order to get the 388 to put out the same bass level as the 275 i needed to turn it up quite loud, louder than I would enjoy listening to.

It's a good article. I think you just need to match levels properly before you can judge. You also seem to be using the volume knob position as being important in this....