# Before and after speaker mod, did i ruin it?



## BowerR64 (Nov 4, 2009)

*What do you think of my mod results?*

What do you think of my results? The stock plot (red) is the stock pioneer tower with the top working driver then a tweeter, squaker thing and the bottom 6.5" is a passive radiator.

I added 2 12ohm drivers devided the top 2 speakers small like a little book shelf, then the bottom has a large front port. The top 2 drivers are rear ported with a small rear port. First one i moded blue and the second is greenish color.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Moving to DIY Speakers Forum...

Regards
Wayne


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## glaufman (Nov 25, 2007)

Personally I think it's hard to say from these plots as there are significant room effects at work, masking what the speaker is truly doing.


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## BowerR64 (Nov 4, 2009)

Im not sure i know how to smooth out the room effects with this program


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## fbov (Aug 28, 2008)

I disagree. His data's telling us he's got problems. 

Below 200Hz, where room effects dominate, the curves have similar shapes telling me that the room wasn't changed - peaks and dips are all at the same frequencies with different drivers. Bass reflex tuning can explain most of the level difference. Above 200Hz there are large differences in response due to driver and XO changes in the same room. How do those mask one another?

That said, this is a mess. The top octave is missing, the XO change traded one big peak for another and the replacement driver chosen isn't up to the output level of the drivers it crosses to, nor does it like such high box tuning. I won't touch what happened to the passive radiator. 

I won't say anything's ruined except the passive radiator, but only because there wasn't much worth preserving. The tweeter would be the first driver I'd swap, to eliminate the peaks and regain the top octave, but that needs a crossover design that meshes with the other drivers... hopefully you see where this is going. 

It is very rarely beneficial to swap drivers randomly, requiring lots of measurements and simulations to figure out if drivers can work together, and what sort of circuit design is needed to merge them seamlessly together. It can be done, but it's a long and steep learning curve...

Let me know if you're interested; I can point you to some starting points.

Have fun,
Frank


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## glaufman (Nov 25, 2007)

Of course the room hasn't changed. But much care needs to be taken to ensure identical placement in the room of both speaker and mic. Peaks dips haven't changed frequency. All that means is that they're modes. The frequency a mode is at depends on the room, not the placement of the equipment in it. What that mode does to the response however can be affected by placement in the room, a dip can get better/worse, or become a peak. So despite the long wavelengths, I don't trust the comparisons in the bass region. That being said, I AM a suspicious person by nature :sneeky:

Back to the OP. Assuming the speaker has to be measure in room, best method is to placethe speaker and mic symmetrically across the center of the room, 1m apart. I don't think you mentioned what mic you're using, but assuming it's the RS meter since your labels specify a C weighting, I would point it directly horizontally at the speaker, on level with the tweeter(s). You could also look at the impulse response to check for reflections that could be gated out.

Also, if it's the RS meter, you can't trust any reading above 3kHz. So the comparisons at the top end don't hold water either.


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## BowerR64 (Nov 4, 2009)

It is the RS meter, the newer analog one with the different db settings on it.

I think i have issues with my room, i cant seem to find info on how to correct the room.

When im not testing or doing anything i have 40-45db of noise from the room. The mini fridge, the furnace, the computer not sure what all its picking up but its not quiet for sure.

When i tested these i was i think 12-13' from the speaker and it was in its listening position where i would sit and watch movies.

I know everything is messed up with it but it wasnt a really good speaker from the start. No crossover in it just a few caps and a ceramic fuse thing. Its all open inside with a few sections of insulation but not enough.

I think more then anything i want to learn how to better use this REW tool. The speaker i care less about actualy.


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## glaufman (Nov 25, 2007)

Might be relatively simple to track down the source of the noise. Monitor the noise using RTA mode to see what frequencies its at. Turn devies on one at a time to see their individual contributions.
For room correction, what you do is usually dependent on what problems you have. Some surefire things are corner traps. Next is often panels at 1st reflection points. After that, who knows...
Well, Bryan over in acoustics knows. As does Wayne in Equalization. There are others as well, so poke around, read a bunch, ask some questions, and enjoy the process!


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## BowerR64 (Nov 4, 2009)

:nerd:


glaufman said:


> Might be relatively simple to track down the source of the noise. Monitor the noise using RTA mode to see what frequencies its at. Turn devies on one at a time to see their individual contributions.
> For room correction, what you do is usually dependent on what problems you have. Some surefire things are corner traps. Next is often panels at 1st reflection points. After that, who knows...
> Well, Bryan over in acoustics knows. As does Wayne in Equalization. There are others as well, so poke around, read a bunch, ask some questions, and enjoy the process!


Wow, i cant even find the RTA. That is short for real time analizer, right?


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## glaufman (Nov 25, 2007)

Sorry, go to the Spectrum tab... you can place that in RTA mode.


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## BowerR64 (Nov 4, 2009)

I put a devider between the 2 drivers and added a port in the rear of the top section. I put the devider between the 2 tweeter things.

Blue is the stock Tower, purple is 2 new drivers with a single front port, red is with a devider and rear ported the top chamber devided the top like a bookshelf.


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## BowerR64 (Nov 4, 2009)

Would the peak around 46hz be where its tuned to with the 2 drivers and the single port? After i added the devider the peak seems to move closer to 50hz


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## BowerR64 (Nov 4, 2009)

I went ahead and did the mod to both towers. I like how they sound better then before. The sound before had good midrange but with out a sub they just didnt have anythickness. Now they sound very full but seem to lack a little of the midrange the stock drivers had.

It was very fun to do and REW was great to test the different changes as i went.

First i just added the port at the bottom, then i added the 2 drivers with the 1 port, then i added a devider, then a port to the back of the top chamber.

My first plots were with the stock onboard video card wich looks really noisy, these are with an older SBlive gamer sound card.

Red is the stock speaker with a 1mfd cap on the tweeter, blue first speaker, green is the second after all the mods. I also took the 1mfd cap off the tweeter and put the stock .33 back on both towers.


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