Time for a little update again.
I've been working a lot with the listening room lately. In this process I've done impulse response and ETC (Energy-Time-Curve) measurements. When I did them I saw some "clutter" with very short delay after the direct pulse from the speaker, and thought I'd had to find out what is was. The time gap was much too short to be any room reflection. I didnt actually solve it, but on the way I installed some foam around the tweeter, which flattened the frequency response of the tweeter a little bit. There were small ripples at +/- 1dB or so in the response from 2 to 5 kHz, they were reduced with the foam. Also the impulse response became a little bit cleaner.
A pic of the modification:
I've been working a lot with the listening room lately. In this process I've done impulse response and ETC (Energy-Time-Curve) measurements. When I did them I saw some "clutter" with very short delay after the direct pulse from the speaker, and thought I'd had to find out what is was. The time gap was much too short to be any room reflection. I didnt actually solve it, but on the way I installed some foam around the tweeter, which flattened the frequency response of the tweeter a little bit. There were small ripples at +/- 1dB or so in the response from 2 to 5 kHz, they were reduced with the foam. Also the impulse response became a little bit cleaner.
A pic of the modification:
An externally hosted image should be here but it was not working when we last tested it.
Yup . . .
http://www.irf.com/technical-info/refdesigns/iraudamp7d.pdf
THD+N charts beginning on page 8 . . .
Populated boards available from classDaudio, cheap.
And an other update.... new amps:
The ICEpower amps powering the main dipoles have been replaced with a Hypex build, two UcD180HG powering the tweeter and mid, and two UcD400HG powering the four 8" woofers.
These amps are really great, highly recommended!
An externally hosted image should be here but it was not working when we last tested it.
The ICEpower amps powering the main dipoles have been replaced with a Hypex build, two UcD180HG powering the tweeter and mid, and two UcD400HG powering the four 8" woofers.
These amps are really great, highly recommended!
I wouldn't be surprised if you were to find damping of the magnets on the mids to be worthwhile. Just a 'lil wrapping of acoustic felt or foam.
Hi StigErik,
Could you please describe the differences between the Hypex and the ICEpower amps with regards to sound?
Thanks!
Best regards
Peter
Hypex is more open, transparent and dynamic. Less grain and cleaner sound all over, but most noticable in the treble. More "true to the source signal" if you know what I mean?
ICEpower sounds a bit warm and closed-in, especially in the treble and upper mid.
I'm keeping my ICE 1000ASP for the subwoofers though, they are simply superb there.
ICEpower sounds a bit warm and closed-in, especially in the treble and upper mid.
I'm keeping my ICE 1000ASP for the subwoofers though, they are simply superb there.
A few more changes again:
1. XO between low and hi-mids changed from 500 to 400 Hz. Slightly better.
2. Revised the overall gain structure so that I can run much higher level in the digital domain, and get better resolution (in theory at least). This was done by installing L-pads at the inputs of all power amps, and to adjust the analog output level of my DAC to the lowest setting. Tweeter and upper mid is padded down as much as 20 dB.
1. XO between low and hi-mids changed from 500 to 400 Hz. Slightly better.
2. Revised the overall gain structure so that I can run much higher level in the digital domain, and get better resolution (in theory at least). This was done by installing L-pads at the inputs of all power amps, and to adjust the analog output level of my DAC to the lowest setting. Tweeter and upper mid is padded down as much as 20 dB.
With the 180HGs operating at 6dB gain 16 bit data to the DAC should be reasonable. Particularly as your typical listening levels are probably a few dB louder than mine---find I start hearing the 16 bit floor around 15dB gain on the power amps with clean tracks, give or take a few dB depending on the recording.
What sample rate are you running?
What sample rate are you running?
Yes - the bit depth through my system is 24 bits. I use a squeezebox, it outputs a 24-bit signal, and all bits are used unless the volume control is at 0 dB. Then the lowest 8 bits are static at 0. My XO and EQ software process at 64-bit depth, but input/output will be 24 bits. My DAC is also 24-bits. But the lowest 4 bits are probably lost in the noise floor...
I'm never going to live long enough to learn half of this stuff
Yes, if you were brought up with analog it's a lot easier to wrap your head around, isn't it? At least it makes some sort of intuitive sense.
I thought grain = harshness = intermodulation distortion and is a function of speakers (or at least the majority of) ?
I'm a fan of Class D (using Sure atm.).
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