So i need to design some surround speakers
The impedance is correct, but there is something going on with your response measurements. First, they should be a little louder, closer to 80-85db. Do you have your measurements in omnimic taken as blended? Did you move the mic or change the volume when taking measurements? Were they all taken at tweeter level about 16" away from the tweeter?
Which tweeter and woofers are these?
Yeah i took the measurements from tweeter level, 16inches away and i didnt move either the speaker or the mic. But i was using an amplifier with a low level as i was worried about the tweeter, should i have turned it up as it was running sweeps until it got up to 85db? But yeah i had a big hump at 50hz with the tweeter measurement
Oh and yes i had it at blended but i didnt realise i needed to add 5ms in the other box so that was zero. I didnt change the volume between sweeps either,
the drivers are pc83 and td20f-4
Also just so you can check what i did to produce the sweeps was right, i played them from my laptop, out through the headphone jack and into the amplifier, i let it run for 10 seconds or so then paused it. I then went to the top left corner and saved the curve, i did that for all the measurements. But obviously i had the amplifier too low (schoolboy error)
PS - you don't really have to leave it running. When you get a good measurement, just pause the program and save it. You probably weren't getting a big hump at 50hz from your tweeter. That was probably something else in your room. Just make sure you are using an amplifier that is not dsp'd. Same with your computer. ANy special audio processing should be turned off. No added bass or treble.
Thank you for taking the time to teach me with this, i really, really appreciate it, i appologize for not replying sooner, it was after 4am here and i fell asleep.
Ill have a watch of the video you kindly made and i will try and get new measurements taken today or tomorrow, using what ive learned from you and once ive done that ill upload them on here, if you wouldn't mind just taking a quick look to see if they are better this time?
As far as i know the laptop and amplifier play with normal settings, i think the 50hz tone was being picked up from my radiators being on, everything in the graph was moving slightly but the 50hz peak was stable, didnt move at all, so ill try turning up the volume this time and having the heating off.
edit: so ive just watched the video, that helps immensely, thank you, hopefully my new measurements and crossover can benefit from this.
With regards to the 'delay' of the tweeter, i thought that a componant of the crossover would physically delay it so that the sound left at the same time, i hadnt realised it was just allowed for in the crossover, thats clearer for me now too
Ive just noticed you said to take the freq resp first then the impedance so that it's already set volume wise, im not sure how to do that as the dats produces its own tone, i dont use the amplifier for that test, and the dats sweep sounds quite low to be honest, probably around the same level as i took my original measurements. Is there a way to increase its volume to match?
Ive re run these measurements today, i increased the volume and turned off any source of noise i could find in this room, but im still getting that shitty tweeter response. Could it be that behind my speaker i have a metal radiator set back about 4 feet? or could it be a port issue?
Ill add all my new measurements in this post just in case you can spare a minute to see where im going wrong. If not i understand, and im grateful for the help youve already given me. While using xsim to work out the z offset (which is way easier than the other way, thankyou for that) i found that they line up better if i add a 0.7 delay to both woofers, as im running them in series. I know im being a pain with this, i apologize, i just wish i could just get it to work and not have to bother you anymore. I think the tweeter issue is whats causing me to have these problems though, so ive taken a port measurement too, 2mm inside the port at exactly the same volume of the amp etc as the other measurements. And if i re run them again im going to set up in a different room. Also i had it set to blended with 5.0ms
At this rate im gonna have to start paying you for your time!
I'll try to take a look sometime later this week. My internet went down and the earlies they can come fix it is Saturday.
Thank you,i appreciate that, and its no problem, im going to finish the speakers and leave the tweeters and crossovers disconnected until i can find the reason for the wierd tweeter high end when i try to overlay them. The tweeter response on its own seems to be not too bad? The problem occurs when i try to put them all together. But at least i can use the system with just the woofers for now as luckily i picked full range ones lol
Just thinking out loud here, but as i typed that, i realised something, as the woofers are full range, and im testing with no crossover, could the wierd dips at the high end be due to the woofers also playing the same frequency during the tests but having a different response to the tweeter? If not i must be doing something wrong during the measurements, although im trying to match instructions the best i can