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So i need to design some surround speakers  

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Dameo182
(@dameo182)
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19/10/2020 6:23 pm  

I think you have helped me finally figure this out, it was driving me crazy, as i thought that my settings were wrong or something, turns out im just an idiot lol. I put in all your components as you did, and i got the same result as you, thank god. So now i should be able to make future crossovers on my own and i can finally move onto the subs, and then i can order all my parts and get on with this build, thankyou!

cntre channel crossover
cntre channel response
cntre channel impedance

 


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TVOR-Ceasar
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19/10/2020 9:25 pm  

Yes, the last one you did works correctly.

I just copied the one that Nick did, since it was basically the same type of setup, just a different tweeter. Then I played with the values to flatten things out. So if you use the one I did and switch the cap between 2.7 and 2.2, you'll see a slight difference. It'd be up to you to choose which you'd think best. My hearing is colored now, so I'd probably like a more tilted top end. (Age does that to you). 

The notch, I would only use that if necessary to correct something that couldn't be fixed with the original first x-over. 

Baffle step, this is one I'm one the fence about. Usually it drops the output of the top end to match the bottom end, ultimately lower efficiency, and really like most of the stuff we are pre-designing, needs to be verified in a build and measurement. Since you are using MTM style with a port, you are already helping to mitigate the effect of baffle step. Not really sure if it'd be needed. 

One last tip, if you are not already doing so, keep a page open on your website of choice, ie Parts Express or similar, to the caps, coils and resistor pages. That way you can choose from what's available instead of trying to track down a nonstandard value. 

-Charlie


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TVOR-Ceasar
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20/10/2020 9:45 am  
Posted by: @tvor-ceasar

...

Baffle step, this is one I'm one the fence about. Usually it drops the output of the top end to match the bottom end, ultimately lower efficiency, and really like most of the stuff we are pre-designing, needs to be verified in a build and measurement. Since you are using MTM style with a port, you are already helping to mitigate the effect of baffle step. Not really sure if it'd be needed. 

...

@123toid

Nick, I know you are still on the mend. If you could, at some point, chime in with your thoughts on whether Baffle Step is needed in this instance, we'd appreciate it.

Get stronger and better each day. 

-Charlie


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Dameo182
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20/10/2020 3:46 pm  

@tvor-ceasar

I really apreciate all of your help with this, i would probably have given up trying to do that crossover if you hadnt noticed my mistake. As for the tilted top end, i would prefer it to be lower if poss, ill probably adjust slightly to see if i can get it a bit lower, only reason being is that the review i watched about this avr said it can be bright on the trebble end if matched with the wrong speakers, as its coloured in a way to imorove the voices etc. So it may be best to lower it a little. 

With the baffle step  i use the online calculator, which worked well for my last two builds, so i just wondered, since xsim doesnt have the ability to add volume and baffle size maybe getting a flat response without the BS circuit, then adding that in to the wiring later might have a more accurate response. But as you know, im a complete novice so my question was mainly a way to understand how it works in that xover. And if this was a midrange or sub in this build, would they too need a baffle step or is that purely for full range drivers? 

Speaking of subs, im looking at which to use, i think im going to go for 2 (seperate) w5's in vented enclosures. Alot of the bigger ones dont seem to go as low as those and are 4 times the price in some cases. I also need to find a good quiet amp, do you have any recomendations? 


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TVOR-Ceasar
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20/10/2020 5:52 pm  

@dameo182

For the top end, mess with the resistor value to see it peak up or down. And like I said earlier, if you go with 2.2 uF, it will smooth it just a tad more. You could always order several values and try them out.

Baffle step is something I don't mess with much, so I'm still very much the neophyte there. Very basic understanding, but that's more or less it. Plus, you have to weigh the pros and cons of using it. Is the efficiency loss worth it for the response, or will it be compensated by the subwoofer's upper range? You sound like you know the baffle step frequency, what would that be and will the sub play high enough to smooth that out?

Amps? Since you want to use 2, why not go with a Class D stereo amp, at least 50 watts. You could try the Dayton Audio dspb-250, 2 channel , 50W with built in DSP. I only know what the reviews say, so take it with a grain of salt. I'd like to hear from others who have more first-hand experience with specific amps. Anyone? Bueller? Bueller?

-Charlie


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Dameo182
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21/10/2020 7:56 am  

@tvor-ceasar

 

Yeah ill try that tonight after work, im happy with it as it is but im just a bit wary of making that avr sound too bright, better safe than sorry

The frequency is 723hz, with an 8 db drop. In that case i need a 6ohm resister and a 1.3mh inductor, tbh the way i see it, its because the tweeter is taking over the high frequencys, then the baffle step is just to bring down the full range to create the crossover point. And the extra inductor after the bsc brings it down even more. Allowing the tweeter to take over, so now i think about it, maybe the baffle step in this case is just a way to bring down the full range' highs completely, to almost nothing? Instead of just slightly, im on break again so appologies if this doesnt make much sense lol. Basically i think, its meant more as a high frequency killer in this xover rather than to even out the response? 

Thanjs, ill take a look at that amp later, as i have some questiins about how it will all work together 


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123Toid
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21/10/2020 10:07 pm  

@dameo182

A quick reminder.  Assuming your receiver has a setup microphone, it sets trim adjustments for each speaker.  The 165w is typically just 2 channels driven.  On top of that, if your trim is set down, -3 for left surround, for example, this will also lower the wattage to that speaker.  Also speakers handle more wattage the higher they go up in frequency.  Said differently, the higher you cross it over (to an extent) the more power it can usually handle.  Most surround speakers are not full-range, so crossing over by 80hz should not be a problem for most speakers. Think about, the Bose cubes, there's no way they could handle 100w, yet they are fine on most surround sound receivers. 


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TVOR-Ceasar
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21/10/2020 10:41 pm  

This is the post with the link to the AVR's manuals. Page 11 of the operating instructions shows a calibration mic, so there's that. It's actually a nice looking AVR, spec wise.

@123Toid , what is your opinion on a BSC network for this MTM build? I'm unclear as to if it's needed.

Also, what do you think of using the amp I linked above with a pair of W5's? DSP would help out with keeping it simple, I'd think.

Lastly, the 2 main L/R speakers, when they are to be used in 2 channel mode, I have a couple ideas to toss around, mainly a big bass blocker cap to limit bottom end to them and maybe a 6" or 6-1/2" woofer to add onto the bottom to give it the lows it needs for music. Not necessarily a sub, but a good, matching, musical woofer. Obviously, that would be @Dameo182 's call as to what to do. Of course, that would be later on, after all the extra work has settled down with that special arrival coming soon. 
Only reason I mention it is that the AVR only uses the Sub Outs for multi-channel. 2 channel deactivates them.

Again, that's for down the road. And of course, you guys know that once something starts running through my head, it tends to spill out. 

-Charlie


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123Toid
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21/10/2020 10:51 pm  

@tvor-ceasar

It is needed, just not as much.  Should only need about 3db attenuation. The issue that I have with the current crossover is the huger hump caused by the tweeter at 1800hz.  That will be very audible and will sound quite forward.  If it were me, I would work on that area some. 

I didn't see the amplifier but I am sure it is fine. 


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TVOR-Ceasar
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21/10/2020 11:17 pm  

That hump is from the Tweeter x-over cap.  A 2.2 would drop that hump down to almost flat. It's basically your Reveal x-over slightly modified to work with a different tweeter.

I suggested the Dayton Audio dspb-250, 2 channel, 50W with built in DSP. That way he could use that DSP to help get rid of anything over what's not needed and still have enough oomph to drive the W-5's. Or would you recommend something a bit more higher powered?

-Charlie


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123Toid
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21/10/2020 11:50 pm  

@tvor-ceasar

That is a good amplifier and you could make some basic adjustments to it.  I knew it was the Reveal MTM with a different tweeter, I am just concerned with the crossover still. That tweeter should be crossed over closer to 3500hz.  The FS is around 1700hz, which is one of the issues with the hump.  It will probably add a lot of distortion to the tweeter. I would completely rework the crossover to help crossover much higher with that tweeter. The basic rule of thumb, is to crossover twice the FS (2nd order) and FS should be about 20db down or more. Currently FS is closer to 7db down.  All in all, without measurements of distortion, I am confident to say it is not going to work out well.


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Dameo182
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22/10/2020 8:06 am  

@123toid

Firstly i hope your feeling better now, nice to see you back on this forum! 

Well i figured it saying 165 watts per channel was a bit exhagurated so are you saying i might get away with making the surrounds to contain just one pc83 and a tweeter rather than the mtm style? It would save me some cash, and im always happy about that lol 

As for the crossover, my initial thought on that was that the tweeters range is from 3000hz to 20000hz, and i wondered if crossing over so low was an issue, but given that ive literally got no experience or much understanding of the way crossovers work, as in whats good and whats bad, i was planning to try it out and adjust it from how it sounded if needed. So after your input, thanks for that btw, ill have another go at it tonight and see what i can come up with. Ill post it in here for you to critique, if you dont mind that is.

I think ill use the amp that @tvor-ceaser suggested for the subs, im not sure how the dsp works though as i dont see any adjustments on it, i may figure it out if i spend more time looking through the specs. Ive just been preoccupied with these mtm speakers, they're kinda stressing me out now

 

 


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Dameo182
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22/10/2020 4:17 pm  

Ok so ive had another attempt, ive done the best i can from my ability and i feel a bit anxious posting this as i feel like your gonna say this doesnt work either, im losing hope in ever being able to be competent at designing crossovers for my builds without having to come to you for help all the time, i dont mean to be a pain, i just dont know where else to learn this from. Anyway if you could cast your eye over this and let me know how far off i am, and be gentle please lol @tvor-ceasar @123toid

atempt 2 crossover
atempt 2 crossover response
atempt 2 crossover impedence

 


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TVOR-Ceasar
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22/10/2020 9:58 pm  

It looks good to me. My X-over computer is in use at the moment, so I can't go over it in detail.

-Charlie


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Dameo182
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23/10/2020 1:27 am  

@tvor-ceasar

Yeah its no problem, thanks for getting back to me, i couldnt seem to flatten out the area after 10000 without changing the crossover point, it flattens nicely if i raise the point to around 6000hz but im not sure if going higher will be any kind of issue, i would think it would be ok..but there could be some hidden reason to not do that that im not aware of yet.

Are you feeling back to normal now since your surgery? I hope so 


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