[Lee Rambler]

so I finally took the time to rta my car yesterday, and after a little 1/3 octave tweaking with the bitone, this is what I came up with. It's a little boosted at the low frequencies still, but I just prefer the sound that way... or my mic is just biased that way (pretty cheap one from an audessey kit). the cool thing is none of my boosts/cuts were more than 1.9db, most less than 1db. I've always found that anything that requires a huge boost/cut is often phase related and you cant really fix it anyhow (which I believe is the case in the 300hzish problem). I also think the 14khz peak is a mic issue as it's done that with several different systems and I don't notice it. I have the tweeter level on the quart crossovers at -6db, and it appears that ideally there would be a -4.5db pad, as -3db is too hot and -6db is just a bit soft. And, unfortunately, even with 1/3 octave in the bitone there are some problem areas that aren't addressable as they are between bands. Wish the bitone had a few bands of parametric eq to fix things too... All in all pretty happy with the results though, I did one preset on the bitone with eq and another without so I could a/b it (with crossover and t/a the same), and it's surprising the noticable difference the small adjustments make.

[Lee Rambler]

apparently the image is too large to upload...

[Lee Rambler]

had to resize it, hope it's still large enough to see...

[fdriller9]

Cool. Thnaks Lee!

[raceyBMW]

You could upload to Imageshack or something like that and then link to it here so we can actually see it.

[Lee Rambler]

If you or anyone else wants the full size image (or if you happen to have Praxis software, I could even send you the rta file), just pm me your email and I can send it to you...

[raceyBMW]

Here you go:

[Lee Rambler]

thanks raceybmw!

[jjmanda]

I would be curious if there are any common problem frequency areas for the e90's/e92's.

I put in a pair of 1/3 octave EQT's this past weekend and will have a shop RTA and tune in a couple of weeks.

I believe only Rainman can probably accurately tune 30 bands by ear.

Are there any quality "affordable" RTA's useful to DIYers?

[raceyBMW]

There is an app on the iPhone that is supposed to be halfway decent. Not professional by any means, but gets the job done. Someone else will have to tell you the name of the app though, because I can't remember off hand.

[Lee Rambler]

there are a number of inexpensive programs for a laptop, praxis being the one I use - though it is a bit cumbersome and can be intimidating to use.

I believe the 300hz -ish area is a problem in the car, as is the 1.7k or so peak. I don't think they are oem eq related as the bitone should have handled anything there, it's possible they are a problem in the quarts I'm using too. Will be doing Ryan's car in the near future, and he ended up getting some morels - so we'll see if the same areas are problematic, or if it's driver related.

[jjmanda]

Originally Posted by Lee Rambler

there are a number of inexpensive programs for a laptop, praxis being the one I use - though it is a bit cumbersome and can be intimidating to use.

I believe the 300hz -ish area is a problem in the car, as is the 1.7k or so peak. I don't think they are oem eq related as the bitone should have handled anything there, it's possible they are a problem in the quarts I'm using too. Will be doing Ryan's car in the near future, and he ended up getting some morels - so we'll see if the same areas are problematic, or if it's driver related.

Yes, I too have attenuated the 315hz and 1.6khz frequencies.

I also think I have a peak around the 160hz area. That may be a driver issue as I'm currently using Morel MW166's under the seats. I've tried both leaving the enclosures unsealed to the vehicle side skirts and sealed as well. Because of the high Q of the MW166's, I'm thinking the enclosures should be left unsealed.

I would be interested in your results in Ryan's car with Morels. I'm sure VP Electricity has plenty of RTA results using Morels as well.

[jjmanda]

I have neither an I-Phone nor a laptop. I'm lacking in these technological devices.

The Praxis software looks interesting. Looks like it uses a mic in to the PC soundcard. I guess I could get the demo mode for RTA purposes and haul my desktop up from the basement to the garage.

[Lee Rambler]

1.6k isnt the problem, it's 1.7 to 1.8. there's actually a little dip at 1.5-1.6k (at least in my set-up). I didnt see a issue at 160hz, but it could also be crossover related in your setup. I would definitely leave the underseats play into the sill part of the enclosure, it would be really small if not.

you can pick up a netbook for pretty cheap and then have it to use in addition to as a rta

[jjmanda]

Originally Posted by Lee Rambler

1.6k isnt the problem, it's 1.7 to 1.8. there's actually a little dip at 1.5-1.6k (at least in my set-up). I didnt see a issue at 160hz, but it could also be crossover related in your setup. I would definitely leave the underseats play into the sill part of the enclosure, it would be really small if not.

you can pick up a netbook for pretty cheap and then have it to use in addition to as a rta

Thanks for the info..the EQT doesn't have a 1.7khz or 1.8khz adjustment. It jumps from 1.6khz to 2khz.

I'm going back to unsealing the underseats. A while back I filled the enclosure with rice to measure the volume and if I measured correctly came up with like 0.1 cuft or close to that. That's pretty small indeed.

As far as the 160hz, it's hard to say trying to judge it by ear. I am bandpassing the mids from 70hz to 200hz with 12 db slopes. I am crossing everything over using a pair of Zapco SLX2's.

[IllLojik]

Originally Posted by raceyBMW

There is an app on the iPhone that is supposed to be halfway decent. Not professional by any means, but gets the job done. Someone else will have to tell you the name of the app though, because I can't remember off hand.

Signal scope pro. It's what I used to set my eq. decent lil app.

[Lee Rambler]

third octave eq's are at 1.6k and then 2k, that's the problem... that's why I wish the bitone had a couple of parametric bands too. brining 1.6 and 2 down to tame 1.8 doesn't do you any good when you have dips at the center frequencies already. You exaggerate one problem to take care of another

[jjmanda]

I fiddled around last night and this morning with my setup.

Lesson learned number one: I unsealed the underseats and indeed the MW166's need air.

Lesson learned number two: When using a pair of Zapco's SLX2's, it's best to give them their own input signal. When feeding the input of one from the output of another, weird things happen with the output level of the second one. Zapco tech confirmed this behavior with me, but can't explain it.

The bass mellowed quite nicely once I corrected both these things.

Thanks Lee and sorry for the highjack

[Ocelaris]

Lee, what system did you start with, with the bitone? The Hifi with low-level inputs on the Bitone or the high level from the Logic7 ? I heard the Bitone needed a decent signal, and thought the Hifi (which I have) was a fairly weak signal).

Thanks for the input, will definetly be trying out that TrueRTA software!

[Lee Rambler]

I unfortunately have L7 as my starting point. I think I'm going to get a da1000 so I can run an optical signal into the bitone. the hifi is a great starting point, already a flat signal. consider yourself lucky...

[VP Electricity]

TrueRTA in full version is what I use, so I can look at 1/24, 1/12, 1/6, or 1/3 octave modes.

You can download a pink noise WAV file for CD with a 10M track from Rockford's 360.2 support page.