Its Alive ! ! !

Madmike2

Member
2005-04-24 11:55 pm
Toronto
Well one of them at least, i messed up the holes last week for the other. I put this on left channel with the Pioneer 737 for power. Against my KRK Rokit 8 active monitors. PWNED !! Wow what a difference even with my jury rigged X-over, This isnt a "OMG this thing i built kicks butt" comment. I had friends sit in the middle as well. We got it as close as possible to similar SPL and then played one song. Completely dwarfed the KRK which are built for NF but none the less. Man i cant wait to get the other one fixed and see what this baby can do without the subs. :D :D :cool:
 

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Madmike2

Member
2005-04-24 11:55 pm
Toronto
hmmmmm there seems to be something strange going on. Its almost as if its out of phase in the top end when i move back a to a certain position. What does the comb effect sound like? Nothing is out of phase because its a LR 24 db x-over and its all wired correctly. Just sounds weird at one particular spot. A 'box' if you will thats 8 feet back at 3 feet in hieght. The 'box' itself sounds about 1.5 cubic foot in size if i move my head around in it. I am thinking my x-over is off :xeye:
 

Madmike2

Member
2005-04-24 11:55 pm
Toronto
Cool. SO i got to play around some more i guess. Out of curiosity are the wire wound resistors better then the big white ceramic jobs i bought ? i have 3.9 and 3.3 ohm 100 watt ceramics for my Tweeter attenuator. I was wondering if i would have been better off with wire wound. I used fast caps but i couldnt find air core inductors so i am using iron core. I am guessing i will have to swap those out eventually ?:confused:
 

ShinOBIWAN

diyAudio Member
2004-02-25 9:13 pm
UK
Whilst I hate to put weight on individual components and kead you to believe that swapping out fr higher priced/better quality alternatives will end all your problems and give you very noticably better sound.
But it sounds o me like your using some rather bad choices for xo components. Firstly the iron cored inductors should be swapped for air cored as soon as really, nothing fancy required so I wouldn't both with Goertz copper foil or anything like that.
Also the resistors you are describing sound very much like the wirewound ceramic types, if they are white in a rectangular package. Most here would recommend non-inductive types or metal oxide(MOX) types. To be honest I never noticed any difference between the types myself.

For the future I'd consider going active for sure, Of course you'll need a total of 6 amps for a stereo 3-way setup. But its one of the most effective upgrades that you can do, aside from another speaker using even better drivers.

Regarding your suspected phase problems: Do you have speaker work shop or lspCAD? You could either model or analyse the loudspeakers using either of these program then post the graphs and data here for us to take a look at and we could suggest what was wrong and how to improve things.
 

Madmike2

Member
2005-04-24 11:55 pm
Toronto
Ok i have them both working now. I butchered the cabinets pretty much fixing my offset screw holes. Not to bad all in all. No leaks anywhere.

As for the sound well, lets see. I can no longer listen to any kind of MP3 under 320. They sound like an ex girlfriends voice. If i play FLAC files or any of my other hi bit rate music it does not distort till hi volume.

The mid is way bright. I have to drop it 3 to 6 db between 300 and 3k on the cheesy winamp EQ.

the sound stage as i was told IS not very big. When you get about 7 feet back at couch height its awesome. I have never heard a few things on some of my music as i am now. A cliche but its true.

The highs are not broken glass crispy. The mid bass hits like a smack. and as for lower bass, the black eyed peas and Esthero have no problem pu8nching me in the gut. Its not as deep as my KRK ported cabs but much better. I cant say faster because i wouldnt know how to quantify it but it is 'better' .

This pioneer 35 watter i was so enamored of i think is not going to be much use to me. Also when i measure the impedance static and hooked up to amp at the speaker itself i am in the mid 30's. Is that the x-over holding a charge and affecting my readings ?

I have a x-over that i never sold i just dont have 6 amps. Even if i use this Rane i still need to have this top end dialed in since i will have 4 speakers total when i am finished what i plan on doing.

A couple quickys then ill listen to whatever is told to me.
What kind of sound would i hear if the Iron core saturate ? A distinct break up in the spectrum when a sustained low note comes through?

Also since i have heard tubes on above average speakers before ( i had SOnic frontiers, MC 30's and various speakers before.) i do remeber a bit of a 'sound' on the highs that was very distinct. I get that now and i am on a solid state amplifier. You all think mabey this amp is cakked ?


Lastly, i know that i probably goofed this x-over up horribly, even though it is tolerable to me (and better then what i had) Is there anyone in ontario who KNOWS what they are doing that would be willing to let me courier or drive this up to them and let them experiment and set them up. Ill pay not a problem. I dont have the tools or the skillz to measure and play as i go. When its all said and done i want them closed up never to be opened again. Ill even by another super tweeter to top off the cabinet if i must. :rolleyes:

If anyone wants to know what my x-over consists of just enter 6 ohm tweeter 8 ohm woofer with 9 db of attenuation x-over 24 db per octave at 2k .

Now i am going to the gym i have been listening to this for 4 hours now. Its better but not great right now.

ShinOBIWAN Thanks for useful comments . I answer any questions you want.

:dodgy:
 
Do you have a delay in your tweeter path? You might want to examine the time domain behaviour of your drivers - to a first approximation around the crossover frequency, woofers act like 1st or 2nd order lowpasses, and tweeters are typically 2nd order highpasses. The corner frequencies are determined by the characteristics of each driver. Even if the LR4 keeps you well away from the amplitude rolloff of each component, you still need to contend with the phase issues inherent to the driver rolloffs (drivers are typically a minimum phase system, which means you can predict the phase response from the amplitude response and vice-versa).

At a wild-*** guess, I'd say you have somewhere around 90 degrees of phase shift between the woofer and tweeter at 2 kHz, if you chose the crossover point midway between each driver's rolloff. I'd need to look at driver measurements to give you any sort of a more accurate answer.

Another thing to consider is the path length difference between the drivers - your woofer is deeper than your tweeter so sound takes a bit less time to reach your ear from the tweeter than the woofer. Sound travels at about 1100 feet per second - I use 13500 inches/second - so a one inch difference is about 75 microseconds, or about 50 degrees at 2 kHz.

Add all that up (90 + 60 = 150) and your tweeter's pretty well out of phase with your woofer at your crossover point. So, you might ask, can you fix that by reversing the tweeter leads? Well, that'll fix the problem at the crossover point but it messes up the response above and below crossover, albeit not as badly.

You can test the above by temporarily removing the tweeter, covering up the hole, and mounting it above the cabinet set back by about three inches to see whether that sorts out the problem.

By the way, do you have baffle step compensation in the crossover?


Best of luck,
Francois.
 
Nope . I did not do a BSC because i know what it is but i dont know how to properly implement it. As for the tweeter and woofer alignment, they are pretty close , the big ribbon is set back in the chassis pretty far and just eye balling it top down i put them about a centimeter out.

The 90 degree out of phase thing has my attention though. What can i do in the x-over to negate that?