Ask an Acoustic Engineer (me)

[geolemon]

That's an interesting goal and a hell of a challenge - let me toss out a crazy idea...
Remember these? https://www.parts-express.com/speake...s/bass-shakers

I have a set, from like 2 decades ago - someone gave them to me for something, maybe I traded them for something... never played with them (I guess "yet").

I don't know how your bike seat is - mine I don't think I could attach it, but if you have a little space below the metal seat pan, and especially if the seat has a suspension to decouple it from the bike - I bet this would be a great use for these.

I've been mulling over selling my bike and buying a convertible, and since there's also zero cabin gain there, I was wondering about trying that out. But I think your motorcycle might be a good application - I'd think people in the bike world might have already tried this though.

[Justin Zazzi]

Well-done bass shakers are impressive!
They are a bit puzzling to "tune" though lol

[ean611]

I just created a presentation on this for my office actually. The interesting thing is I only have one target curve. The trick is to realize as much of that target as I can, given the number and types of speakers I have available, the amplifier power available, and the kind of vehicle I have.

With a sealed cabin and a pair of 12" woofers and a thousand watts of power, I can realize the whole target curve. But on something like a side-by-side vehicle or a motorcycle where I only have 6.5" speakers and an open cabin, I cannot reproduce all of the lower frequencies in my target curve so I get the most bass out of the system that I can... up to a point where I cannot any longer.

I'm always aiming for the same thing, but I cannot always achieve the same target based on the practical limitations of what I have to work with.

I do not think I can share the target curve I use at the office since Rockford has not shared it publicly, it is considered part of our secret sauce. There is a great thread on diyma titled something like Comparison of Target Curves and there is some really fascinating discussions in there.

The only question I'd have here is the science/reasoning behind the 2k-ish cut in the Jazzi curve on your spreadsheet. I know why I'd do something like that if I'm mixing a choir together, but on the reproduction side, curious why you have -dB bump there. I've found that in my car, this bump helps with my target, and I need target curves with Dirac Live, but would love any reasoning you can share on that.

[Jdunk54nl]

For me, it goes back to the fletcher Munson curve. Between 2-4khz we are the most sensitive in hearing. I find that, in the near field listening environment, I need that area cut or my ears get tired listening real quick. Also the "tings" from some cymbals or instruments are brutal without that cut.

In my home listening or far field. I no longer need that cut, but also have more of a downward tilt in the general curve due to natural high frequency roll off.

[Justin Zazzi]

The only question I'd have here is the science/reasoning behind the 2k-ish cut in the Jazzi curve on your spreadsheet. I know why I'd do something like that if I'm mixing a choir together, but on the reproduction side, curious why you have -dB bump there. I've found that in my car, this bump helps with my target, and I need target curves with Dirac Live, but would love any reasoning you can share on that.

This was mostly trial and error. No matter how many times I tuned, some piercing screechy stuff was always bothering me and it turned out that a cut in that range was what I needed to tame it. For me.

I tried adding this cut for a few other people's cars and they liked it, so it became part of my routine.

Also, jdunk's reply too.

[Jdunk54nl]

This was mostly trial and error. No matter how many times I tuned, some piercing screechy stuff was always bothering me and it turned out that a cut in that range was what I needed to tame it. For me.

I tried adding this cut for a few other people's cars and they liked it, so it became part of my routine.

Also, jdunk's reply too.

Same, I never really enjoyed my tuning curves until I started to introduce that cut. It was just too brutal on my ears. My wife said the same thing when I tuned her car.

[Cathul]

And another vote for that dip in the curve.
I know from a technical point of view and for competition you would never do that, but for daily listening it makes it much less fatigueing, especially when you listen to Rock, Hardrock and Metal due to the compressed nature of the guitars sounds in these genres.

[Stycker]

My car has a natural dip in those frequencies. Its part of the natural response from the interior of my car. When I try to flatten it out, it becomes more obvious. Lucky for me, as I hardly have to eq my mids. My ears are most senitive to this area as well.

[Cathul]

My car has a natural dip in those frequencies. Its part of the natural response from the interior of my car. When I try to flatten it out, it becomes more obvious. Lucky for me, as I hardly have to eq my mids. My ears are most senitive to this area as well.

I thought that, too, but then i found out that this dip dissapeared after adding a dedicated midrange to my system.

[ean611]

This was mostly trial and error. No matter how many times I tuned, some piercing screechy stuff was always bothering me and it turned out that a cut in that range was what I needed to tame it. For me.

I tried adding this cut for a few other people's cars and they liked it, so it became part of my routine.

Also, jdunk's reply too.

Thanks.

This dip really helped smooth out my sound. Given I'm using Dirac Live for the final curve, I can dial it in precisely. Before I installed my tweeters, it made the sound more pleasant from the ScanSpeak 10m. Since the, added Arc Audio RS 1.0 Tweets in pods around sail panel area, and this dip still helps.

I find it interesting that Audyssey does a very similar dip, centered around 2KHz. They call it "midrange compensation"