[BroDoze]

Originally Posted by AdonisP91

Ok so it looks very promising, let’s see how BroDoze’s test work out. What I am thinking we should do is see who might be interested in this forum, looking at the other models not only the g87 and g42 folks.

Then we can do a bulk buy. For example, let’s say 3 ppl are interested. We buy 3 for 900$ (assuming the Global Sources ones come with the wiring harness). BroDoze led the charge as the guinea pig so we need to compensate him. He paid probably like 900-1000$, so we have the 3 bulk units plus BroDoze’s unit, so 4 in total split between us all. ~500$ each.

If more people join the bulk buy we can get the costs down. If 9 people wanted to bulk buy, we would have it down to like 360$ a piece. Thoughts?

Very generous offer. I want nothing, as you and many others in this forum have been paving the way on a lot of this stuff. Payment would be the ability to keep picking y'all's brains as I fumble my way around ATF, lol. Maybe I'll get brave and get into REW - I'll really need some help then.
I knew I was paying the high "early adopter" price when I went into this. Glad to help where I could. Let me know if you have any questions.

[AdonisP91]

Originally Posted by BroDoze

Very generous offer. I want nothing, as you and many others in this forum have been paving the way on a lot of this stuff. Payment would be the ability to keep picking y'all's brains as I fumble my way around ATF, lol. Maybe I'll get brave and get into REW - I'll really need some help then.
I knew I was paying the high "early adopter" price when I went into this. Glad to help where I could. Let me know if you have any questions.

When I get the car, I can show people REW. It looks intimidating but it really is quite easy once you get the hang of it. I was thinking we could do a discord group chat/stream, where we all tune together.

[AdonisP91]

The Global Sources distributor confirmed that the units come with the wiring harness and the software is sent via email or WhatsApp. But thanks to Celica, we already have the software now. The preamps are listed at $320 USD, minimum order 3 units. Not sure about shipping costs yet.

[BroDoze]

I’d be curious about app version and firmware upgrades on the device. I mean, there’s not much to it. If it works, it works, not much need for upgrades I guess.

[kenkamm]

Maybe I'm jumping a bit ahead here, but I'm really looking forward to the first frequency response curves from the system with this preamp installed. Previously, AdonisP91 pointed out a huge dip between 80 hz and 160 hz in the stock system. I thought it looked like the stock crossover rolloffs may have something to do with it. I believe he said he thought it maybe be a destructive interference issue. Either way, it sure will be interesting to see what BroDoze's curves look like when he applies a RTA to his system.

[BroDoze]

I think that dip was all the crossovers. ^^

From what I can tell, the vast majority of 4” midranges say their freq response runs down to 110hz-120hz, some say even below that. I think that’s low. BMW thought is was low too, apparently. The other thing is, they can avoid a lot of blown speaker warranty claims if they hi-pass cross them up at 160hz.
I think the biggest issue is they don’t have a real midbass driver. So instead of running their underseat “sub” up to 150/160, they cut it off where you would a normal subwoofer. Maybe because in some cars the subs are not all under the front seats? And in those cases it sounded bad having “subs” running up into that range? Since we know BMW doesn’t time-align and they don’t EQ per-vehicle they gave us configurations that are supposed to work across all of their models, which is absolute crap, for what these cars cost. I mean it’s the same setup in a $160,000 XM right? That’s really bad.
I think if BMW would have said to their engineers “we need a minimum 5” door speaker in all of our models” they would’ve ran the hi-pass across all cars down near 110hz. There’s a big difference between a 4” midrange and a 5” midrange/midbass driver.
So it’s BMW that hosed us. They only put 4” speakers in the car, forcing their audio engineers to build in this stupid crossover gap and I guess those same engineers didn’t like running the underseat woofers up higher to fill that gap.

That’s what I’m going to attempt to do with a 150hz 24db lo-pass on the underseat woofers and a 24db 150hz hi-pass on the midranges.
When I was experimenting with a hi-pass (for a bandpass) on the underseat woofers, it seemed like moving up the 20hz lo-pass to 30hz didn’t result in much of a loss at all. I did notice a significant loss in response moving the lo-pass up from 30hz to 40hz. So I’ll probably do a 30hz-150hz 24db bandpass on my Alpha-One underseat woofers. I will also try to see what I lose between 150hz to 160hz. Maybe the 4” would just be happier up at 160hz, so then I’d run the underseat woofers up to 160hz. More listening required there.
With my 12” trunk sub, it’ll probably be a 20hz-60hz/70hz 24db band-pass. So a lot of overlap on the low-end. Not sure how that’s going to sound. I don’t want to run the underseat woofers hi-pass much higher than 30hz because I lose a lot of nice bass response up front.

[kenkamm]

Originally Posted by BroDoze

With my 12” trunk sub, it’ll probably be a 20hz-60hz/70hz 24db band-pass. So a lot of overlap on the low-end. Not sure how that’s going to sound. I don’t want to run the underseat woofers hi-pass much higher than 30hz because I lose a lot of nice bass response up front.

For what it’s worth, the guy that took first place last year in IASCA’s top sound quality competition had a pair of 12” woofers in the rear and a 10” in the front in the passenger footwell. He didn’t reveal his crossover points in the articles I read about his car but with the two drivers being nearly the same size, you can bet there was plenty of overlap. I think you’ll be fine. Perhaps with the DSP you could even phase match them using REW!

[BroDoze]

Originally Posted by kenkamm

For what it’s worth, the guy that took first place last year in IASCA’s top sound quality competition had a pair of 12” woofers in the rear and a 10” in the front in the passenger footwell. He didn’t reveal his crossover points in the articles I read about his car but with the two drivers being nearly the same size, you can bet there was plenty of overlap. I think you’ll be fine. Perhaps with the DSP you could even phase match them using REW!

I’ll have to have AdonisP91 come out and get down n dirty with REW, for beers, lol.

So because I run my trunk subs so much hotter than I should, not to mention my house curve will have a small smiley face from 800hz to ~4khz I’m not going to be popular amongst the purists that lean towards a flat curve. My curve will look nothing like the car’s I used to build and couldn’t stand listening to because they were a perfect RTA curve. Blech. I’m cringing thinking about 1-2Khz right now.

[AdonisP91]

Overlap is a good thing. The way I see it the point of the RTA and EQ'ing with REW and so on, is first to get a nice frequency response that takes out all the dips, the cancellations, interference, etc. Then we can adjust it to whatever we like since we are starting from a system that performs well from a technical standpoint.

If that means a smiley curve like BroDoze likes, great. If it means flat, great. If you like midrange compensation or high frequency roll off, great.

Ok, now to my point, why is overlap good. Forget about the curve shape and where I selected the cross overs. Also I was only EQ'ing to about 150 hz, so forget about what happens above that range. Also, keep in mind this is with 1/48db smoothing so it is very detailed data.

We start, as always, with the arbitrary target:


Now I measure and EQ my subwoofer in my home theatre at position 1. This is what happens:


Unsatisfied, I try a new location:


This is a bit better but not great. What would happen now if I bought a second sub, ran both of them together, one in each position. This happens:


Is the dual sub perfect? No, but it let's both subs complement each other. With 3 or 4 subwoofers, imagine how smooth the frequency response could be.

This is one of the main reasons why in competitions for car audio you see the trunk and front subs, they will work in unison and sound fantastic.

[BroDoze]

I love my dual SVS subs + Audyssey + SubEQ.

How did we ever get along without dual subs?

Oh I remember - big-ass ported 15” sub in the corner huffing and chuffing and you could point and say “See! There’s my sub!”

[AdonisP91]

Originally Posted by BroDoze

I love my dual SVS subs + Audyssey + SubEQ.

How did we ever get along without dual subs?

Oh I remember - big-ass ported 15” sub in the corner huffing and chuffing and you could point and say “See! There’s my sub!”

The SVS subs are amazing. Audyssey is a real pain in my ass though. I love a bunch of the Audyssey features and the MultEQ-X has so much potential, but I wish they would just let me turn it on manual mode and disable their room correction.

You take measurements in REW, find the proper filters, and then import them into MultEQ-X. It should be happy days like when using the ATF DSP PC tool. Instead of just doing exactly what my filters and targets ask it do, Audyssey applies its own adjustments on top according to what it predicts is needed. So now when you take a new REW measurement there are new issues you have to sort out.

It becomes and back and forth guessing game. I did eventually get it dialled in though.

[BMW DIY Guy]

But then for those of us without the extra addon gear (holy crap great work there guys), are we still looking at a better amp tune? I know it isnt perfect but still a lot better, and also is it better than the tune from Maciej? I know he puts a ton of work and pride into his tunes.

[BroDoze]

Originally Posted by AdonisP91

The SVS subs are amazing. Audyssey is a real pain in my ass though. I love a bunch of the Audyssey features and the MultEQ-X has so much potential, but I wish they would just let me turn it on manual mode and disable their room correction.

You take measurements in REW, find the proper filters, and then import them into MultEQ-X. It should be happy days like when using the ATF DSP PC tool. Instead of just doing exactly what my filters and targets ask it do, Audyssey applies its own adjustments on top according to what it predicts is needed. So now when you take a new REW measurement there are new issues you have to sort out.

It becomes and back and forth guessing game. I did eventually get it dialled in though.

Yes, there are definitely certain things I don’t like about it, too. I wish I could set a house curve in Audyssey. It’s powerful, but has limited options and control.

[BroDoze]

Originally Posted by BMW DIY Guy

But then for those of us without the extra addon gear (holy crap great work there guys), are we still looking at a better amp tune? I know it isnt perfect but still a lot better, and also is it better than the tune from Maciej? I know he puts a ton of work and pride into his tunes.

Tom, are you still tweaking your profiles? I have kind of blown past the state where any sort of profile I have now would work in another car. I never really ever had one fully finished where I’d feel comfortable sharing it, and it was only doors, woofers, rear surrounds and trunk sub anyway. No center or rears.

The digital pre-amp is so different in sound the two couldn’t possibly translate. I checked my time alignment and it was a near direct match pre and post pre-amp install, but levels and EQ are way off.

I got a lot of time in the car tonight. Had to revisit the pre-amp volume settings again. It’s amazing when you think you have stuff dialed in, and you sleep on it and the next day you’re like WTF? Ear fatigue I suppose.
I turned the blinker on and is was a bit too loud and the PDC noises were not quite loud enough. It’ll probably take 2+ more times to get it perfect, from what I remember those volumes being, stock.