Test Music - Albums

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Tony_R

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TNTTNT: .....so I got the meter out last night and did my own mental plots and curves. I found a huge room spike at 42hz, followed by an enormous trough at 65hz climbing back to 0db at 78hz. The spike at 42hz sent the needle off the meter. What ever was causing the suck out at 65hz was pretty severe, because even the sub hardly affected this, even at moderate gain.

As a matter of interest, how are you calibrating your measuring equipment? Does the microphone / transducer you're using have a uniform response at these frequencies?

Or are you just using it as a rough guide to a 'relative' response?

It seems that you need some quite expensive sophisticated equipment to get a truly accurate response measurement..

http://www.paradigm.com/en/paradigm/r_and_d/anechoic_accuracy.php
 

Terryff

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The first two portishead albums will give you miles of deep bass. Here's a very alternative suggestion, the skyscaper album by David Lee Roth has bass by Billy Sheehan which is fast and complex with good drums behind it.
 
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Anonymous

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Tony_R:

TNTTNT: .....so I got the meter out last night and did my own mental plots and curves. I found a huge room spike at 42hz, followed by an enormous trough at 65hz climbing back to 0db at 78hz. The spike at 42hz sent the needle off the meter. What ever was causing the suck out at 65hz was pretty severe, because even the sub hardly affected this, even at moderate gain.

As a matter of interest, how are you calibrating your measuring equipment? Does the microphone / transducer you're using have a uniform response at these frequencies?

Or are you just using it as a rough guide to a 'relative' response?

It seems that you need some quite expensive sophisticated equipment to get a truly accurate response measurement..

http://www.paradigm.com/en/paradigm/r_and_d/anechoic_accuracy.php

Hi, I am using the radioshack analogue meter and desktop, with a dedicated audio soundcard (Terratec).

With the PC, I feed one of the PC line outs to a PC line in, to form a feedback loop to calibrate the soundcard, which my software allows me to do. The software gave me the facility to load a calibration adjustment file for my make of soundmeter, which I downloaded and fed in.

I have checked up on my meter, and one made by Galaxy is much more accurate, but also 3x the price. I did some further research, and my meter has a reputation for being pretty accurate in the low bass end of the range. It isn't deemed very good for the midrange and higher. It quotes error of +- 2db.

Looking at the calibration file, it seems to gradually add 1db between 40hz to 60hz, but otherwise is flat as a pancake.

The problem with using just a measurement approach is that it treats all the range with equal importance. If I had to ruin the 30hz region to get a flatter response above this, I would. This is based on the fact that the 30hz frequency may not be active very often with music.

The metering has given me an idea of how my room behaves and it has been interesting and useful. I rang PMC about something, and we chatted a bit. I told the gentleman what I was up to. He said "I bet you get a huge suckout at 100hz". I was gobsmacked, because he was right. He said it was the interaction between the floor and ceiling. I have found sites which, after fed with room dimensions, have predicted huge blowouts in the 40hz area, so again I found this quite interesting.

So far the community have given me some good ideas for test track, as I have been astounded by how the mixing and recording quality of some of my CDs vary (adversely a lot of the time). I don't have many CDs where I trust the quality of the bass, and again the community have helped.
 

Tony_R

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TNTTNT:
I have checked up on my meter, and one made by Galaxy is much more accurate, but also 3x the price. I did some further research, and my meter has a reputation for being pretty accurate in the low bass end of the range. It isn't deemed very good for the midrange and higher. It quotes error of +- 2db.

It sounds like you have certainly been doing your homework..

However - bear in mind that +-2dB is almost a doubling of the amplitude...

+3dB is double the amplitude.. so 2dB is actually a massive error in real terms!!

For really accurate results, you probably want to be measuring to a resolution of +-0.2dB.
 
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Anonymous

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Tony, one thing I wouldn't picking your technical mind over is phase. I have found that as the crossover aproaches 100hz on the dial, the phase goes haywire. So at this level the volume goes down when the sub is switched on, and up when sub is off The phase shift seems to be 180 degrees.

I solved by keeping crossover lower, at 80hz, but I found this really wierd.
 

Tony_R

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TNTTNT:
Tony, one thing I wouldn't picking your technical mind over is phase. I have found that as the crossover aproaches 100hz on the dial, the phase goes haywire. So at this level the volume goes down when the sub is switched on, and up when sub is off The phase shift seems to be 180 degrees.

I solved by keeping crossover lower, at 80hz, but I found this really wierd.

You sub should have a phase switch on it. What you're seeing is phase cancellation - i.e. your speakers are pushing whilst the sub is pulling (if that makes any sense).

So changing the phase switch should cure that. If there's no phase switch on your woofer, then swapping the + - on each speaker will do the same thing, but then the 'absolute phase' will be incorrect, although I'd be surprised if you could hear any difference...

If what you're seeing is simply with the sub alone - this could be down to one of two things - either your room has a massive resonacne at that point, which could cause an apparent (note I said apparent) phase reversal - or it could be some anomaly with the port on the sub (assuming it has one).

Given your level of knowledge I'd be surprised if you haven't already spotted the phase reversal switch though..
 
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Anonymous

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Tony, Thanks for taking the time to jot down your thoughts. I don't think the system is out of phase because it seems in phase until the crossover goes to 100hz. I think your suggestion of some wierd stuff happening with the room might be closer to the mark. The sub does have a port as well.

I don't think I will find out for sure, but appreciate your ideas.
 

Tony_R

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TNTTNT:
Tony, Thanks for taking the time to jot down your thoughts. I don't think the system is out of phase because it seems in phase until the crossover goes to 100hz. I think your suggestion of some wierd stuff happening with the room might be closer to the mark. The sub does have a port as well.

I don't think I will find out for sure, but appreciate your ideas.

One thing I neglected to mention - all ported speakers exhibit some kind of phase 'oddness' at differing nodes.

So it's quite possible even your speakers (assuming they're of the ported variety) could be interacting with the sub at that particular frequency.

If the port on the speaker is tuned to say, 50hz, there will invariably be some kind of node at 100hz.

Try bunging the ports, if any...
 

margetti

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May 29, 2008
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RainMeister:
Dark Passion Play by Nightwish - comprises 4-piece metal band, symphony orchestra and large choir. You get a lot of double bass drum, and a very attacking style of bass guitar to test the sub. Add in powerful female vocals, choirs and the odd boy soprano and it's a fair test of a system afaik. I've been told the first song has around 300 individualÿtracks within it, and takes a good system to hear it all. I've not been able to verify this myself though.

As you go through the album the variety is immense - hard gothic metal, "power ballads", quite commercial metal, power irish/finnish folk and topped off with a great arrangement with a gospel choir.

Available on CD, DVD-A (5.1) and vinyl.

Bought this at lunch time on the back of your post and.... WOW! And I'm only up to the 3rd track. Unable to really crank it up right now, but will at some time over the weekend for sure!

Also bought Exodus and Supernatural but will have to wait until the missus has watched Eastenders to listen to them...

ÿ
 
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Anonymous

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I'm glad you bought Exodus - It could be a compilation album in it's own right. I have a vinyl compilation with a lot of the Natty Dread album on, and if you like Exodus, you might like Natty Dread.

Beat me too it. I can't wait to see how my tuning fares with the Nightwish recommended, amongst others.
 

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