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Discussion Starter · #1 · (Edited)
My curent ongoing project is a 1990 VW Bus (transporter, vanagon, T3, T25... whatever you call it where you are from :D).

The goal was to make a dynamic sounding system that is SQ orientated, but can play at quite high sound levels.

The curent setup.
Source: Intel Atom D2550MUD2, 2GB DDR3 ram, 30GB SSD for the system, ebay 120W car PC PSU, Audigy 4 sound card with KX drivers, 15.1" touch screen in dash.

Front system: Faital pro W6N8-120 in ported boxes in the dash (I think about 10l tuned to 90Hz? Forgot) driven by a Alpine MRV-1000 and Faital Pro HF100 compression drivers for highs driven by a Alpine MRV-t300.

Subs:
2x Digital Designs 2515a (first series with more spiders than later series 25a's) in a huge 4th order bandpass box that doubles as a bed, driven by a Sinus Live SL-A1500

Some pics of the system:




















The system is quite close to the goal I set for myself. The sub plays at 140dB (flat except for a 3dB peak at 40Hz) from 27-80Hz (Or probably higher, but the TL I was measuring with only goes to 80Hz), the front is plenty loud but there are a couple of problems.

First of all is that the stage is a bit low for my liking (on top of the dash, not at ear level). The bigger problem is sibilance from the (hornless) compression driver when playing as low as I need. I'm guessing it's a problem with my rear mounting and short radius waveguide. Tried stuffing it with felt and it's better, but still not close to the clarity of the Selenium ST350 supertweeters that I use at home.

The other problem is the jagged response in upper range of the midbass. I've been thinking of cutting off the dustcap and making a wooden phaseplug to fit onto the polepiece. Anybody have any experience with doing something like that?
 

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Discussion Starter · #3 ·
Bit the dust and attacked my mids with a knife.




The mid-upper end response cleared up quite a bit. The whistling at the beginning of "Isn't She Lovely" by Livingston Taylor (Focal CD3 track 2) stopped cutting into your ear. Also the big spike at 5kHz seems to be missing now, so I can cross over a bit higher which the tweeters like a lot. The usable frequency range has widened at the top end, but the maximum frequency seems to have dropped quite a bit. I'm guessing they chose quite a thin dustcap to extend the on paper frequency response to 10kHz, but it's so jagged over 5k that it's unusable for SQ.

Still battling with the compression drivers a bit. Any advice would be appreciated.
 

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That was an interesting undertaking! Im glad you had the results you did with the 5k issue no resolved. Im unfamiliar with compression drivers, hope someone will chime in for you with advice. Your modification looks very good!
 

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Discussion Starter · #5 ·
Thanks!

The 5k peak seems is probably more a problem with reflections or the shape of the dash, because I got the peak with the mids and the highs.
Alto my measuring mic isn't calibrated and is probably far from linear (mostly use it for impulse response, not RTA work), it's the only system that I get that peak. I'm borrowing a Behringer ECM8000 soon so I can tune the system a bit more precisely.
Yesterday I wanted to measure the system again, but my monitor stopped working (would turn on for 2s and then die again). The one thing I really didn't want to do, ever, is take the monitor and dash out :(

The cradle for the monitor cracked a bit while I was removing it so I will have to sort that out as well. :(

I was guessing it would be a bad capacitor causing the problems, but I found this on the backlight switching board:


Under the burned protection were two NPN transistors which measured OK, but I replaced anyway


Plus replaced the cap on the board (originally 220uF, 25v, but I went with 220uF 16v becouse it's a generic board meant for a wider array of voltages, but in my application 12V is the max it can see) :


Not a lot of cooling in the dash so I cut a RAM heatsink for the two transistors and attached it with Tesa two sided tape which is quite a good conductor of heat and strenghtened it with a bit of neutral silicone (and I also did the stabilizer for the main bord):


The monitor now works but the touch screen is acting up a bit. Have to take it apart again and check all the connectors.

If luck has it I will be receiving new OP amps for my Audigy card (LM4562MA) by the weekend. Besides the OP amps I'm replacing and deleting a couple capacitators and bypassing the squelching transistors on the output.
 

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Discussion Starter · #6 ·
Got new Op Amps today and went to work on the card.

First thing I did was add capacitators to the voltage stabilizers (If anybody has a audigy that has cracking sounds, especially when cold, this plus a bigger cap at the PCI bus solves it):


Removed the original Op Amps (just put a big blob of solder on both sides and heat one side, then the other untill they fall off) and cleaned the surface for the new units:


New Op Amps in (LM4562 MA, only replaced the surround channels because I don't use the front channel which originally has a even more inferior op amp):


Final mod was removing the muting transistors. Extra transistors in the audio path are never a good thing. I have to delay the remote to the amps a bit so there will be no turn on cracking.


I tried bricking the coupling caps but the sound degraded severely so I undid that.

Did it make a difference? Maybe. It's probably a placebo effect, but the bass sounds tighter, instruments sound more distinct and the highs smother. It's probably just the psychologic effect of having modded something :D

Tried taking a RMAA measurment before and after but there's something wrong with the line in on this card and I didn't have the will to set up a old machine with two good soundcards for the measurement.
 

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Discussion Starter · #8 ·
Went to set gains with a oscilloscope and found something funny with my SL-A 1500. It was puting out a constant ~250Hz sine wave (that I didn't hear because of the 4th order bandpass box). I've been looking for a reason to upgrade and this was it :D (I will try to fix the amp eventually).


Asked around and scored a nice Cactus Sounds PF 1000.2 for a nice price.
Power 2 ohm : 700W x 2
Power 1 ohm : 1100W x 2
Power 4 ohm Mono : 1400W x 1
Power 2 ohm Mono : 2200W x 1

The sound is quite different compared to the cheap Sinus live.

Comparison and guts:


 

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You don't see cactus around much but they are a solid amp. Some of the best amps for durability I've ever seen in SPL. I haven't heard one in an Sq setup but I imagine it does quite well with all the head room.
 

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Discussion Starter · #10 ·
Played with the RTA. Did left and right side seperatly, this is both sides together. This is for listening while the car is off. When on the road the sub is boosted by ~9dB.
Before:


After (still needs work):


The hole at 300-470Hz is from interference of the left and right side (not there on single sided measurements). I'm guessing there is nothing I can do about that without redoing the dash.
The hole from 70-100Hz is becouse I cut the sub at 70Hz, and the midbasses are tuned to 90Hz. If I raise the LPF for the sub, the stage starts to pull back sometimes. I have to play around with delays a bit more (the subs can easily play up to 150Hz if need be).
 

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Really cool build.
 

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Discussion Starter · #12 ·
Played with a couple of things concerning the top end, which never had enough detail and at the same time was quite fatiguing to listen to.
First I tried removing the phase plug making the drivers just dome tweeters in deep throats. Didn't work well. Just quieter and no better sound quality.


Tried removing the faceplate and quite a few bad qualities of the drivers went away. They were still louder than the FDC silk domes, but lacked a lot od detail. Made a wooden waveguide to help with the lower end and it did work, but the frequency response went to hell with a lot of spikes.


For test nr. 3 I dove into the drawer and found some textile small format tweeters (http://www.usblaster.com/Products/Car Audio/Speaker Sets/Tweeter - dome//USB 1110). Originally they weren't that bad, quite detailed, loud, but got harsh quickly. Put them on the lathe and removed all of the plastic and mounted them on wooden waveguides (made from 12mm MDF) made the tweeters louder, cleaner, play lower... quite a bit of an improvement for a shot in the dark waveguide shape.


Note the super professional mounting :D


After some tuning it sounded quite a bit better than before. I could get away with them, loudness wise, if I crossed them at about 5.5k.
 

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nice work!

stop by sometime, got some toys for you
 

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Discussion Starter · #14 ·
I'll come around when I receive my new tweeters. I'm going to need some ideas on how to design the pillars :D
 

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Discussion Starter · #17 ·
Spent a couple of hours trying different aimings.
100% on axis has a lot of detail, but the the centre image is muddy (I'm guessing problems with reflections from the drivers side window).
Firing between the headrests seems to be a nice compromise with a lot of detail and a tight centre image.


Then I went ahead and started making mounting rings, even thou I don't know exactly how I'm going to go about making the pillars (sucks having bare metal pillars, maybe 2" wide and trying to mount a 4" tweeter to them).







The other project was permanently mounting a charger and quick release power connector behind the rear hatch plus wiring in a couple of power sockets in the interior. All at least splash resistant so no worries about being in a damp environment.
 

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Love the full size tweeters. Wish I could mount in my car.

Sent from my SAMSUNG-SM-N900A using Tapatalk
 

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I can lend you for test JBL C660 gti wave-guides if you want, and I also have laying arround some small format Bi-radial horns 13 x 13 cm for 1 inch compression drivers (JBL 2404)....

you got some big ass tweeters...... maybe some custom made smaller flange since you have mill

why dont you mount your tweeters nearer to Midbass driver?.....maybe you won't need to do custom a pillars...

BtW....have you started DH season yet?
 

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Discussion Starter · #20 ·
I can't seem to get the height right if I start moving the tweeters closer to the midbasses. Ear lever is a good 30cm/12" higher than the dash. Maybe if I redid the dash and extended it a bit higher... But I don't have time to do it again :(

The magnet and terminals of the tweets is so big that I would maybe gain 1cm on eater side with a new baffle.
Since I will have to make the pillars from scratch I'm thinking about glassing over the window seal, so I have a bit more room for manoeuvring :)

I'd love to try the small horns for the home use of the Faital drivers.

The DH season is running a bit late. Today will be the second ride since the last snow. I hope I will actually be able to get to the top of the hill. I've been slacking off. No stamina at all :D
 
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