Nothing much other than the obvious, that is, to appreciate that it's very easy to build an amplifier that amplifies and that it's far more important to focus on the speakers and room, but this has already been said before I imagine. I'll shut up now 😉🙂
Mike,
I have read your other thread and the first amp you are looking for is an amp for the bass sections of your speaker.
Despite what Scott said, amplifiers can make a fairly big difference, althou i think that the quality of mid & tweeter amps have a greater impact — one piece of advice i got from Julian Vereker when i was a youngster was to put your best amp on the tweeters,
I’ve not heard your particular NAD, but typically they are really quite good for the money, and can compare to amps that cost a lot more.
For your bass speakers, you’ll want something with a decent amount of power, clean, and for those a fairly low output impedance. I’d suggest 100-200 w but you can get some pretty decent Class D amps that will work fine in the bass — my experience is that they tend to fall down higher up, they have a very high frequency modulation rate that needs filtering out. I got one of the 4x100 4Ω Sure amp modules, coupled with a modified computer SMPS (i have access to a tech wizard), to drive my subs (4 4Ω CSS SDX10), and it ended up costing under $200.
Used amps can also be had fairly cheap. I have a 2 x 150W dual mono MOSFET amp, labeled SEARS, likely built by Hitachi, that i often use for bass that after all the machinations ended up leaving me $400 in my pocket.
dave
I have read your other thread and the first amp you are looking for is an amp for the bass sections of your speaker.
Despite what Scott said, amplifiers can make a fairly big difference, althou i think that the quality of mid & tweeter amps have a greater impact — one piece of advice i got from Julian Vereker when i was a youngster was to put your best amp on the tweeters,
I’ve not heard your particular NAD, but typically they are really quite good for the money, and can compare to amps that cost a lot more.
For your bass speakers, you’ll want something with a decent amount of power, clean, and for those a fairly low output impedance. I’d suggest 100-200 w but you can get some pretty decent Class D amps that will work fine in the bass — my experience is that they tend to fall down higher up, they have a very high frequency modulation rate that needs filtering out. I got one of the 4x100 4Ω Sure amp modules, coupled with a modified computer SMPS (i have access to a tech wizard), to drive my subs (4 4Ω CSS SDX10), and it ended up costing under $200.
Used amps can also be had fairly cheap. I have a 2 x 150W dual mono MOSFET amp, labeled SEARS, likely built by Hitachi, that i often use for bass that after all the machinations ended up leaving me $400 in my pocket.
dave
"Reasonably similar" amps are, or should be, very nearly alike in performance, according to nearly everyone except those who market them 😀
I also give a thumbs up for Class-D, especially in the bass. I was super pleased with Icepower modules running my woofers. Super clean, very tight.
Thanks again for all the useful comments. I ended up finding a $150 B&K ST2140 on Craigslist, and since I couldn't find a negative review, I figured I'd get them. So far, they've been well worth the money. I'm not sure if it's the extra power (140 Watts vs 75) or the amp itself, but I am hearing things that were previously buried in my previous set-up.
I'm also working to get sound panels (Craigslist is turning to a new hobby - 8 4x2x3" Roxul panels for $100) and once all that's set up, get active cross-overs into the mix w/ these two amps...likely the B&K driving the subs and the NAD 4 channel to drive the mids and highs but will play around w/ that...
I'm also working to get sound panels (Craigslist is turning to a new hobby - 8 4x2x3" Roxul panels for $100) and once all that's set up, get active cross-overs into the mix w/ these two amps...likely the B&K driving the subs and the NAD 4 channel to drive the mids and highs but will play around w/ that...
Mark, I know the answer.
Build one of Nelson Pass' amps! Minimalistic amps just sounds best. That's why the audiophile section of the diyaudio people use to go to the passlabs section.
The anxious people builds complex amps with low THD. Just to be sure, so to speak. But THD is more or less unimportant to the subjective sound quality.
Build one of Nelson Pass' amps! Minimalistic amps just sounds best. That's why the audiophile section of the diyaudio people use to go to the passlabs section.
The anxious people builds complex amps with low THD. Just to be sure, so to speak. But THD is more or less unimportant to the subjective sound quality.
A single ended Class A amp with 2 to 4 actives, although much higher in THD than a more complicated low distortion amp with two dozen actives, will generally beat the low THD amp in blind listening tests. It is the harmonic distortion profile that is important, and the SE Class A amp has that dominant second harmonic and monotonically falling higher orders that human ears subjectively like and enjoy. Just about any low THD amp, even Class D amps, will sound better when driven by a SE Class A preamp. Doesn't need much to do that as two transistors (or a tube and transistor) will fill that role nicely as the load is about a 10k to 47k on most power amp input stages.
Regarding the title of this thread: when I build an amp now, even a speaker amp, I connect high sensitivity headphones to the outputs (through a DC block cap if needed) and use it like a doctors' stethoscope to sort out hum, hiss, ground loops, and other sources of noise. When a speaker amp is dead silent with a 96dB/mW headphone, it will produce much nicer deeper and darker background levels. My best amps will be silent even with 106dB/mW headphones where only the slightest hiss is audible when the inputs are shorted. When it can do that, it is also, by default, a headphone amp. 🙂
Not all speaker amps pass this test, but this is the new standard I put on my amps for them to be truly called great.
Regarding the title of this thread: when I build an amp now, even a speaker amp, I connect high sensitivity headphones to the outputs (through a DC block cap if needed) and use it like a doctors' stethoscope to sort out hum, hiss, ground loops, and other sources of noise. When a speaker amp is dead silent with a 96dB/mW headphone, it will produce much nicer deeper and darker background levels. My best amps will be silent even with 106dB/mW headphones where only the slightest hiss is audible when the inputs are shorted. When it can do that, it is also, by default, a headphone amp. 🙂
Not all speaker amps pass this test, but this is the new standard I put on my amps for them to be truly called great.
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