Matching amp EQs using REW

[ablock]

Hi all.

I have an old DSP amp that was tuned for my outdoor speakers. It sounds great, but I don't know the actual EQ settings because I no longer have the software to configure the DSP. I am replacing it with a new DSP amp for which I do have the software. I figured that there should be some way to use REW to get my new amp close to the old one.

I went ahead and measured a sweep with both amps using my UMIK-1 and then tried to manually adjust the PEQs on the DSP to match the curves. I got reasonably close, but ran out of EQ channels before I could get a perfect fit (the new amp is a Powersoft 604, which has high- and low-pass filters and five PEQ channels).

I thought that I could use REW's automatic EQ to generate the necessary settings in the same way that a measurement can be auto-EQed to one of the preconfigured targets. But I could not figure out a way to make a target from a measurement curve. Is there another way to do this?

For reference, here is the psychoacoustically smoothed curve from the old amp (note how the EQ suppresses the low end; the speakers are only rated down to 60Hz):

And here is the best I could do by hand on the new amp:

Any suggestions would be appreciated. I can post the EQ settings also if that is useful.

Thanks!

/afb

 

[Calypso]

One suggestion is to export the desired curve (old amp) using the REW export feature as text and then in the EQ menu, import this as your target curve. The match to target will then automatically generate the PEQs based on the amount available on your DSP.

 

[ablock]

@Calypso thanks, that's what I was looking for. So I load that under "House curve" in the Target Settings?

 

[Calypso]

@Calypso thanks, that's what I was looking for. So I load that under "House curve" in the Target Settings?

Exactly, you can import the target curve as a house curve. Have a look at the EQ menu and you will see a folder icon which is used to find and load your “target curve”.

 

[ablock]

Yep, I see now. Will give it a try and see how close I can get. Thanks again.

 

[Calypso]

Yep, I see now. Will give it a try and see how close I can get. Thanks again.

Two other points, use 1/12 smoothing for your target curve and use the available PEQs to match the lower frequencies first, then listen. If you are not happy, then wider the filter range which applies the PEQs more broadly.

 

[John Mulcahy]

I have an old DSP amp that was tuned for my outdoor speakers. It sounds great, but I don't know the actual EQ settings because I no longer have the software to configure the DSP. I am replacing it with a new DSP amp for which I do have the software. I figured that there should be some way to use REW to get my new amp close to the old one.

It would be better to measure the electrical output from the old amp rather than make an acoustic measurement, then you could see the exact response you are trying to match.

 

[erileykc]

It would be better to measure the electrical output from the old amp rather than make an acoustic measurement, then you could see the exact response you are trying to match.

This is the answer. Use a build out resistor or pad to attenuate the amp output into a range your audio interface will accept and run a transfer measurement.