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Old 10th June 2013, 01:26 PM   #191
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Allen and Jay, you have both touched on great topics. I have been fortunate enough to spend a bit of time in recording studios in years past, and Allen you are dead on with the deficiencies in a lot of recordings. So many studios over compress the recording that they kill the life in the music, but that's not distortion or frequency response related. Some recordings you just have to wonder what happened; referring to the 1986 album from GTR, a "supergroup" started by Setve Hackett and Steve Howe, former Yes and Genesis guitarists. It literally sounds like someone put a mic next to a vinyl lp while it was playing to record it. It's loaded with static and has zero dynamic range. It is the only unlistenable recording I have in my library. But there are other recordings that were mixed poorly, I'll use Queensryche's album Operation Mindcrime for example. It's and excellent album, but it is a recording that will fatigue you. Specifically because the mid range is too hot, especially the snare drum. The bass guitar is recorded well, nice and punchy, but the kick drum is flat. This album is hot an every system I've ever played it back on. Great content, and parts of it sound good, but that snare drum will peel your face off. While I agree that music types like Jazz lend themselves well to higher sound quality, I think that the producers, engineers and musicians actually pay more attention to the quality of the final product. Jay, I agree that we always make a compromise because of the lack of a "perfect" speaker, and so do the recording studios, which brings me to my next point. I've been there from start to finish through the process of making an album. We were in three different studios, on for recodring vocals and instruments, one for mixing, and another for mastering. The overall sound quality from control room to control room was a real eye opener. We mixed at Step Bridge Sudios in Santa Fe, New Mexico, a studio that has a few grammies in on shelf. I didn't want to leave their booth it was so sweet in there. We brought the monitors from the studio in Las Vegas to Santa Fe(A brand I was importing from Germany at the time), and they sounded better than I have ever heard them. And this difference in response and quality astounded me. Now I can't listen to music without thinking about what the enginer was listening to when they mixed and mastered the album. The equipment this work is done on will shape the sound of the final product, meaning playback in the control room. Some have subwoofers, some do not. Some use Yamaha NS-10M monitors (A huge number), and other do not. We are always going to be subject to the artist, producer and engineers interpretation of what every instrument should sound like. The more they eq and process, the more they are influencing what we hear. All we can do as audhiophiles is try to assemble components and speakers that playback only what the source supplies...but isn't that why we are on this forum in the first place?
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Old 11th June 2013, 02:31 AM   #192
AllenB is offline AllenB  Australia
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Just to clarify for the benefit of those are not familiar, linear distortions include things such as frequency response and group delay. Though it is relatively easy to produce a speaker with a flat response, if you toss it in a room you'll likely be subjected to a multitude of complicating reflections and issues of diffraction. The main problem with this as I see it is that this acoustic environment will throw off the frequency response in narrow bands, and introduce quantities of excess group delay.

Logically this issue can't be fully undone by electrical means, including tweaking the crossover. It is usually the best not to even try, though it can be difficult to identify sometimes just whether a given problem is of this nature or not without measurements.
Quote:
Originally Posted by Soundimpressions View Post
The equipment this work is done on will shape the sound of the final product, meaning playback in the control room.
...and a sudden (high Q factor) issue like this over a small range of frequencies could make a particular track or instrument harder to listen to, harder to hear, or harder to identify... despite the speaker sounding reasonably well balanced or measuring well when measurement smoothing is applied (to make it focus on, say, 1/3 octave bands).

Certainly this could lead a mixer to want to dial back or emphasise a track, and for the wrong reasons so unless they are expected to be an acoustician as well I'd find it hard to point the finger directly at them where the speakers are less than perfect. The old rule of thumb 'if you're not certain about the need to EQ, leave it alone' is probably more true than an imperfect pair of human ears might be ready to believe...but at least most electronic EQ tends to be more gradual than the issues a speaker might produce.

Last edited by AllenB; 11th June 2013 at 02:34 AM.
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Old 11th June 2013, 05:30 AM   #193
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Quote:
Originally Posted by Soundimpressions View Post
It's and excellent album, but it is a recording that will fatigue you. Specifically because the mid range is too hot, especially the snare drum. The bass guitar is recorded well, nice and punchy, but the kick drum is flat. This album is hot an every system I've ever played it back on. Great content, and parts of it sound good, but that snare drum will peel your face off.
Vic Coppersmith-Heaven used to mic all of his productions like this. On vinyl the highs were peeled off by the third listen. On CD or flac download it's bright even today with a kind remaster.
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Old 11th June 2013, 01:00 PM   #194
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Quote:
Originally Posted by AllenB View Post
The old rule of thumb 'if you're not certain about the need to EQ, leave it alone' is probably more true than an imperfect pair of human ears might be ready to believe...but at least most electronic EQ tends to be more gradual than the issues a speaker might produce.
Agreed!
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Old 11th June 2013, 09:44 PM   #195
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Quote:
Angus And Julia - Stone Down The Way
Yep, that's a nice and very good recording.
A good recorded electronic album: Actress - R.I.P.

When designing speakers it is a balancing act: depending on the recording some will sound with too much bass and others with too much highs.
But when most of the good recordings sound balanced with natural voices and nothings annoys me, I'm happy :-)
Sorting out this balancing act is done by playing lots of random songs with foobar, so all kind of music passes.

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Old 13th June 2013, 04:48 AM   #196
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how does one calculate the RMS power handling?
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Old 13th June 2013, 08:34 AM   #197
AllenB is offline AllenB  Australia
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I'd need to ask you how you're approaching this, but I'll give some general information.

Firstly though, there is technically no such thing as RMS Watts. The term is simply Watts. The usage of RMS Watts has come about I suspect because the term Watts is widely abused particularly in audio, as power handling seems to be an overrated thing (no pun intended ). When I use the term Watts myself, I mean Watts in its simplest and true form, unless I state otherwise.

RMS, or root mean square refers to the way that AC is converted to it's equivalent of DC in so far as the equivalent DC voltage that would produce the same amount of heat into a load as, say, a sinewave would. RMS can be applied to Voltage or current, and will be 0.707 of the peak voltage. The normally significant ways to look at a sine wave (for different purposes of course) is for example: the peak Voltage, the peak to peak Voltage, or the RMS Voltage.

When I am interested in building an amplifier and want to know the required capabilities, I'll watch the music on an oscilloscope as I have learned to distrust multimeters at frequencies other than the mains frequency where they're usually designed to work. Then I'll note the peak voltages and study the speaker's impedance curve and impedance phase, so that I can derive the supply rails, current needs, and power.

For a simple operation this can be brought down to applying a single sinewave signal and measuring it with a multimeter at the speaker, or amp terminals, whichever is needed.

If you can tell me what you're trying to do, and how, I'll give you the formulas and methods.
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Old 13th June 2013, 01:27 PM   #198
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Originally Posted by bishopdante View Post
how does one calculate the RMS power handling?
And if you are asking about the power handling capabilities of a speaker driver there are two types, power thermal or electrical, and displacement limited or acoustic power handling. Electrical power handling is the amount of electrical energy the voice coil can handle before it overheats; overheating can cause either an open circuit, or a short circuit. Displacement limited is the power handling that is directly related to the speaker suspension, and the enclosure type. When you exceed displacement limited power handling, a speaker can hit bottom of voice coil travel and damage the voice coil. In some cases, a surround can tear, but you will hear audible distortion or popping when you've exceeded this limit. I believe AllenB has given a perfect description of what RMS means. A speaker manufacturer will spec power handling in terms of power thermal, displacement limited handling is a function of the driver's Xmax and the enclosure. Here is a link with the equations (and a calculator) you need to calculate power handling of a loudspeaker:
Closed Subwoofer Box Equations Formulas Design Calculator Par Maximum Displacement Limited Linear Power Output
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Old 13th June 2013, 07:12 PM   #199
AndrewT is offline AndrewT  Scotland
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The Thermal Power Handling of speakers is generally stated for different conditions. Some good (and honest) manufacturers often give 3 max power ratings.
The highest being the peak transient power.
This peak transient is sometimes the only one stated by the bad (or less than honest) speaker manufacturer.

I have two 8ohms Celestion drivers inside my Tannoy B950.
From memory each has a continuous no damage rating of ~300W for a total of 600W.
The peak rating for the speaker is 1200W and the recommended amplifier rating is 1000W to 2000W into 4ohms.
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Old 18th June 2013, 01:11 AM   #200
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I'll take your suggestion Alan and post what I have.

The box is about 36 high 10 wide 10 deep. My son has fried so far three tweeter coils. I would like to replace the TC90TD5B tweeter with something as good that can handle some real power but I don't understand crossovers, I have a ways to go learn it.

I tried a Dayton Audio DC28F-8 1-1/8" Silk Dome Tweeter 275-070
Specifications: Power handling: 50 watts RMS/100 watts max VCdia: 1.14" Le: 0.09 mH Impedance: 8 ohms Re: 5.5 ohms Frequency range: 1,300-20,000 Hz Fs: 637 Hz SPL: 89 dB 1W/1m Qms: 0.82 Qes: 0.9 Qts: 0.43 Dimensions: Overall diameter: 4.33", Cutout diameter: 2.72", Depth: 1.54" Replacement diaphragm 275-072.

It doesn't sound good.


The Morel MDT-20 from what I have read is no longer made.

Why is the woofer crossover different when a different tweeter is used?

perhaps some tweeter and crossover recommendations.

The amp is a dual mono BrianGT chipamp.


Thank You
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File Type: jpg Morel.jpg (30.3 KB, 164 views)
File Type: jpg TC90TD5-001.jpg (418.7 KB, 163 views)
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