What's going on here?

[89-300ce]

Those are your raw room curves?? They look pretty good. Have you tried the correction?? Do you know what the smoothing is and what it uses to measure MLS or Sine?? This is a system curve for my current DIY set-up. With smoothing of course. One is Sine the other MLS. The measurements are reasonably close.

Yes they are raw cuves. Yes I have tried the corrections, I'll try to get some out. They are smooth as silk. I'm not sure what it uses. The unit is designed more for plug and play than DIY. If it was mine I'd just plug it in and let it fix things. It's that good at it.

http://www.stereophile.com/roomtreat...37/index3.html

Alas, it's not mine, so out comes the soldering iron, etc. , but when it's all done I think I'll have to learn to live with some anomalies.

Jorg

[toddalin]

Yes they are raw cuves. Yes I have tried the corrections, I'll try to get some out. They are smooth as silk. I'm not sure what it uses. The unit is designed more for plug and play than DIY. If it was mine I'd just plug it in and let it fix things. It's that good at it.

http://www.stereophile.com/roomtreat...37/index3.html

Alas, it's not mine, so out comes the soldering iron, etc. , but when it's all done I think I'll have to learn to live with some anomalies.

Jorg

Welcome to the club!

I've been trying to achieve a flat response in my room and know what you are up against. This stuff can drive you crazy and I too may have to live with some anomalies. The idea is too get it as good as it can be using what's at hand or readily available. I feel your grief.

[Robh3606]

Are you trying to adjust your crossover based on these room curves?? If you are why don't you take a couple of close in measurements to minimize the room. You should be able to get a better handle on what the changes are doing. If you run the pots through their ranges where do the adjustment ranges lie?? One looks like an overall the other a trimmer.

Rob

[89-300ce]

Welcome to the club!

I've been trying to achieve a flat response in my room and know what you are up against. This stuff can drive you crazy and I too may have to live with some anomalies. The idea is too get it as good as it can be using what's at hand or readily available. I feel your grief.

My mistake was letting this thing through the front door. If it where an RTA I would have played with it, gotten it as close as I could, and then consoled myself with the belief that some of the room effect is for the most part not correctable. Unfortunately this thing corrects them. Ignorance is bliss.

Jorg

[89-300ce]

Are you trying to adjust your crossover based on these room curves?? If you are why don't you take a couple of close in measurements to minimize the room. You should be able to get a better handle on what the changes are doing. If you run the pots through their ranges where do the adjustment ranges lie?? One looks like an overall the other a trimmer.

Rob

That's an excellent idea. I've noticed that speaker placement does have an effect on that dip.

The R3 pot seems to be primarily for controlling the horn hump, roughly 2KHz-4KHz. I've already switched to the 8ohm terminals of the pot for finer granularity but am still forced to run it at 0 ohms. I'm going to try removing the R5 2 ohm resistor.

The R1 resistor looks like it should be overall high end, but the L1 coil just upstream seems to cause it to effect primarily the upper top end, 4Khz and up. I'm sure it has some effect on the mid but it is far more pronounced on the top. I'm running it cut -2db on it's scale, so also close to minimum. I was planning to use a fixed lpad to bring it to 0db which should also help to bring the mid in line.

You're right, I should get the mic right in there and get a real idea of what the crossover is doing before the room messes it up. Place the mic about midway between the LF and HF and about 4' back?

Jorg

[toddalin]

That's an excellent idea. I've noticed that speaker placement does have an effect on that dip.

The R3 pot seems to be primarily for controlling the horn hump, roughly 2KHz-4KHz. I've already switched to the 8ohm terminals of the pot for finer granularity but am still forced to run it at 0 ohms. I'm going to try removing the R5 2 ohm resistor.

The R1 resistor looks like it should be overall high end, but the L1 coil just upstream seems to cause it to effect primarily the upper top end, 4Khz and up. I'm sure it has some effect on the mid but it is far more pronounced on the top. I'm running it cut -2db on it's scale, so also close to minimum. I was planning to use a fixed lpad to bring it to 0db which should also help to bring the mid in line.

You're right, I should get the mic right in there and get a real idea of what the crossover is doing before the room messes it up. Place the mic about midway between the LF and HF and about 4' back?

Jorg

Even at just 1 meter with the mic located midway up the cabinet, I still see room effects.

[Robh3606]

Even at just 1 meter with the mic located midway up the cabinet, I still see room effects.

Yes you do and you will. Most of the time the room effects are prominent under about 300Hz or so. Unless you can get a gated MLS measurement you won't be able to remove the room artifacts. Even then the shorter the gate the more resolution you loose and you can easilly see this when you compare the gated vs the ungated measurement. He should be able to do his horn compensation and adjustments for his compression driver with less influence from the room close in. It won't be perfect but it should help make things a bit easier. 2-4 ft should work fine.

Rob

[89-300ce]

I quickly did some crossover test last night. I didn't quite match the mic position for measuring from left to right as can be seen by the different levels and response. I do believe I'm going to adjust my woofer coil and cap to bring it up a bit and lpad the horn to bring my controls to mid-point. I'm not sure what's happening at 300Hz. Could that be the back of the box which is about 15.5" deep?


Jorg

[Earl K]

Jorg,

- To remove room effects from contaminating the response curve generated by the woofer / move the measuring microphone to within 1/4" of the woofers cone ( near the dustcap ) . The LF info coming from the ports won't be captured / but in this case you're really testing for smoothness of response above 100 hz .
- You can use an 8 ohm resistor on the HF section of your crossover as a dummy load to completely remove any contributions from the horn/driver , to this new curve .

- Once you have this woofer reference curve , then you can decide what to do regarding the anomalies generated by the rooms surfaces .

[89-300ce]

Thanks Earl,

I'll try that next.

Jorg