8 replies to this topic

[Pyroay]

I am looking to fine tune my midbasses and was wondering how people think is the best way to do this? They are focal utopia 6.5" in fibreglass enslosure in the kicks.

I was thinking run the RTA over it to iron out any noticable dips or peaks, then tune by ear to the Alpine reference disk?

Any other suggestions or thoughts? What track on the Alpine disk is a good one to use?

[Maz]

I would look at getting them in 100% phase with ur subs to try and get every bit of bass upfront.

I'd start with some 50hz 60hz 70hz tones and when adjusting the time alighnment there should be a slight volume peak at certain time alignment settings.

Then use an RTA to find the dips, but then again SQ is subjective and a perfectly flat response actually sounds pretty bad.

[bodapa]

I may be wrong here, but the one of the goals of tuning using an RTA is to make sure that the level difference between frequencies do not exceed 3 dB as that is the smallest difference that can be heard by the human ear.

If I were you I'd first make sure that phase differences, crossover and/or time alignment settings are "correct". That is, even before you start cutting or boosting frequencies you should aim for a smooth frequency transition just by playing with them.

Then after veryfing the result on the RTA that you couldn't get any smoother and there's nothing more you could do then move to the EQ and start cutting/boosting freqs. Playing a familiar disc is helpful here, you don't have to use the Alpine Reference disc (although if you're very familiar with it, then it's ok). Tuning by ear doesn't mean that you stop using the RTA, keep on using it to monitor changes to the freq. response. The goal is still the same, to get a smooth freq. response and transition.

You are sure lucky to have access to an RTA. I'd love to own one, but at my capacity as an end user and this being just a hobby, the cost of owning one is rather overkill.

I'm still learning all this, feel free to comment or correct anything I've written.

Bon

[fuddbutter]

they way you are collecting trophys at the moment i wouldent be changing a thing

whats wrong with it at the moment to warent playing with it?

[Shieldsy]

Bobby_Digital said:

they way you are collecting trophys at the moment i wouldent be changing a thing

whats wrong with it at the moment to warent playing with it?

The fact that it's not getting 100% points and the fact that he is using caasq for what it's there for a basis to improve his current system and set the bar even one step higher!

[Bassaholic]

Maz said:

Then use an RTA to find the dips, but then again SQ is subjective and a perfectly flat response actually sounds pretty bad.

Well actually, ideally you would aim for a perfectly flat response, because that is what should sound best (ie as the recording engineer intended, assuming of course the recording engineer had reference speakers/studio setup and knew what he/she was doing). The reason why an RTA is not often recommended to be used is not because a flat response sounds bad, but an RTA is an inherently flawed system at determining the frequency response in a car. It lacks an important detail for it to be useful at higher frequencies. However, at low frequencies, it will be more useful.

In reality, whether the volume difference between frequencies can be heard at more/less than 3dB is not neccesarily. There is no magical limit, it is a little more complex.... Originally the "smallest difference that can be heard by the human ear" was meant to be 1dB, hence the scale, but that was under a given set of conditions.

edit - actually makes sense now.. LOL

[honour77]

Hey pyro how ya doing? Seems like you're working on the feedback you got at CAASQ(arent we all?)

Personally, i do RTA my system in a manner of speaking, not to flatten the response completely(because it will never sound right) but to EQ out the serious peaks and dips which are always inherent in putting an SQ system in a car lol.

I've found it to be really useful. Except that RTAs are a little expensive but not out of reach for a DIYer. All you need to do is get your hands on a cheap SPL meter(i have one by radioshack and recommend it quite highly for its purpose). With a test tone cd, you just play tones in 1/3 octave steps and record the SPL reading at each frequency you play and with the result, you can plot in a program like MS Excel to get your car's freq response and work your EQ from there. basically doing it this way is exactly the same as an RTA except its a little slower but infinitely cheaper.

I'd definitely recommend you give it a try. hell, if you cant find an SPL meter, just send me a PM and you can come over to my place or something and we can do a few DIY RTA runs to work on your system's frequency response. good luck!

P.S here's an example of the in-car frequency response you can get out of microsoft excel with the recordings you make off the SPL meter and a test tone cd as i mentioned. Its a response from an earlier setup i had(now its quite different though)

http://images.cardomain.com/member_images/.../317150_103.jpg

[Pyroay]

Thanks for all of the input. I am not lucky enough to be sponsored, or have heaps of money but a local shop is prepared to lend me an RTA for a day (mainly because i bought a heap of my gear from them).

I wasn't going to tune to a totally flat frequency response but instead use the RTA to measure if there are any extreme high or low points that may be discolouring the sound, but that i can't pin point with ears. Then tune it in by ear using the EQ for fine adjustments.

Although I am quite happy with my midbass and it is nice and punchy it is my lowest scoring area, hence time to fine tune for maximum marks.

[Maz]

Pyroay as im running sealed midbass speakers also, in my car my 8inch mids have very little low bass extension. They have heaps of mid/high bass though. Plotting in WinISD reflects this perfectly as the system Q is really high.

When i tune my system to sound excellent i boost the really deep frequencies on just my fronts. The only way i can describe it is that the midbass is more 'meaty' while before it was more 'punchy'.

I would use the RTA without the sub running, and actually see how low the fronts play.