Guidance on using EQ

I am wondering if anyone might be willing to offer some specific guidance. I am trying to get a pair of 1988 Kef 104/2 working in my listening room. Have made various measurements and would like to learn more about creating and applying the filters correctly. I am using MiniDSP Umik-1 and have 2x4 HD box output to two Parasound HCA 1000 amps. The 104/2's were modified by me for bi amping and have jumped the woofer crossover. Can post or email measurement files if anyone is inclined to assist. Thank you

Thanks for the reference material. Will definitely get into the weeds once I am a little more proficient and knowledgeable with REW. Also, will be adding some room treatments: acoustic curtains, broadband absorbers, and a couple of bass traps. For now I would like to ask for some help in reviewing the mdat file with the various measurements. I took these measurements with a crossover of 250Hz. No science behind my choice just a guess. Have a great day.

Just so I can track along with you can you tell me which of the measurement files you refer? For example is it the measurement of the L&R MTM without the woofer. Not questioning your observation just trying to be sure I can learn and not ask too many dumb questions.

The comment try inverting the woofer and mids refers to the settings of the MiniDSP?

@ John & Mathew

Did some more listening and I can hear a difference between L & R so decided to take more measurements with two mic (Umik-1) positions. There are 2 files per speaker mic 6" from tweeter and 1 metre away. The R speaker looks better than the left but does have a big dip @3k. The left speaker graph does show a lot of fuzziness / distortion which as John first stated points to a damaged tweeter.

As this is a 30 year old pair of speakers will be difficult to find matching pair of T33 tweeters so I would like to know if EQ will be the answer to the L distortion issue?


I am running bi-amped, so will need to double check the wiring and take some new measurements.

Thanks

Thought that was the case. Will try the connections before proceeding. If in fact replacement of L is required assume it would only make sense to replace both with matching OEM if available or the non factory pair sold by midwest speakers. Thank you will be in touch.

John Mulcahy said:

I'm afraid you can't EQ away distortion. From your close mic measurement the left tweeter doesn't appear to be working now. Swap over the connections between left and right to make sure the problem is in the speaker rather than somewhere else, and check the tweeter wiring, but after that replacement is likely the only option.

Click to expand...

John,

I moved the suspected damaged tweeter from the original position in left speaker to the R speaker and measured again with mic 6" from tweeter. Sure seems to me I am going to have to replace this tweeter. Which is what you suspected. I have uploaded the files for your review and comment.

My 104/2 tweeter is model is TS1191 which are longer available as far as I can determine. Probably go with a pair of Morel MDT29 for now. Cheers

John Mulcahy said:

Pretty big SPL range in those plots, but does look like the problem is following the tweeter.

Click to expand...

For future measurements do you have suggestions on the spl range. Still trying to build knowledge so I can take consistent and meaningful measurements. Good day to you.

Ok thanks. I believe you told me to adjust spl range to use the limit button. I made a screenshot showing my attempt. Have I got it right. Also, what might typical values be for dB top & bottom. Thanks so much for the support.

Think I got it now. Take care

John Mulcahy said:

That right hand side is the axis for phase in degrees, it is the left hand side that needs adjusting - try 105 dB at the top and 45 dB at the bottom.

Click to expand...

Hi John,

Attached are measurements of my Kef 104/2 with both tweeters replaced with Morel MDT 29. Looks like I have working tweeters and need to EQ to smooth out the curve a bit. Will continue following your work. Take care