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Ok, need some advice from experts. I am currently experiencing an impedence rise of 5+ ohm at peak frequency. The setup consists of:
Audiopipe AP30001d amp (3000 rms @ 2ohm) AQ HDC3 15 Alum D1 Box: 4.8 cubes net / port is 108 sq inch tube 21 inches long. Box Interior Dimensions = 45.5 wide / 15.5 tall / 13.5 deep Sub and port firing forward sealed off in intrepid trunk.
posted
rising from 2ohm-5ohm isn't too terrible. not great, but not too bad.
Posts: 5502 | From: Columbus, OH - formerly FL | Registered: Oct 2003
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LOL....Well, when I said 5+ I should have been clearer.. I'm getting a final load of 7 ohms at tuning! I still managed to hit a 146.2 over the weekend but knowing there is so much untapped potential is torture. I can't spend any more money for a recone which really sucks.
-------------------- Cadence CMW6 Components Orion 4004 Component Amp Soundstream XXX-6500D for now AudioQue HDC3 15 Alum D1 151 from the trunk National Champion MidwestSPL Basic Trunk Posts: 93 | From: Des Moines Iowa | Registered: Mar 2009
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impedance is always going to be highest at the note at which your box is tuned. But, your box should have peak output 4-7Hz higher than tuning. the key is to get the box's peak to be at the vehicle's resonant frequency...not tuning the box at the vehicle's peak, but rather several Hertz lower
Posts: 5502 | From: Columbus, OH - formerly FL | Registered: Oct 2003
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posted
having the same issues as you and the only thing i can do is lower the impedience at the speaker so the rise starts at a lower spot. D-Bass do you know of anyone that will build D .35 coils for the DD neo's
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I personally don't know of anyone...especially when you're definitely going to want a high strength composite cone. I'd ask around though.
Can you strap the amps and use a different coil configuration to achieve something similar? I know you don't want to here this, but what I just suggested might be risky, because if you blow a coil, you may then burn up two amps. It's stetsom, it happens...fairly regularly from what I here. Sorry
Posts: 5502 | From: Columbus, OH - formerly FL | Registered: Oct 2003
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So if I am seeing a total impedence of just about 8 ohm at the frequency I want to use for comp, and right now the sub is wired to 2 ohm, would I be correct in assuming that if I par. it to a half ohm I will be seeing just about a 2 ohm load with rise? The amp is 2 ohm stable. Of course I would not try this on music. This would be for burps only.
-------------------- Cadence CMW6 Components Orion 4004 Component Amp Soundstream XXX-6500D for now AudioQue HDC3 15 Alum D1 151 from the trunk National Champion MidwestSPL Basic Trunk Posts: 93 | From: Des Moines Iowa | Registered: Mar 2009
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posted
it's risky. i'll tell you that first. you might be able to get a burp off if you roll the volume
Posts: 5502 | From: Columbus, OH - formerly FL | Registered: Oct 2003
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quote:Originally posted by D-Bass: I personally don't know of anyone...especially when you're definitely going to want a high strength composite cone. I'd ask around though.
Can you strap the amps and use a different coil configuration to achieve something similar? I know you don't want to here this, but what I just suggested might be risky, because if you blow a coil, you may then burn up two amps. It's stetsom, it happens...fairly regularly from what I here. Sorry
these are the new 14k2d 12v amps they do not strap and i have the cones and caps and surrounds just need the coils and spiders.......want to see what they will do with a rise around 1 ohm. they spec at 16.5kw @ 1ohm but in my current set up seeing 3.1 0hms 8540 watts.....
-------------------- 12 VOLTS BABY!!!!! TEAM STETSOM USA & SALES REP TEAM STINGER BUY OHIO GENERATORS WORLD FINALS COMPETITOR 2005,2006,2008,2009 SUPER STREET 1-2 CERTIFIED 161.0 DB MARYLANDS LOUDEST DAILY DRIVER N.S.P.L. STATE RECORD HOLDER 2005,2006,2007,2008,2009 TEAM USAudio Stetsom Sales and Service stetsomrep1@hotmail.com Posts: 2227 | From: Maryland | Registered: Oct 2005
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posted
your box needs to be at least half the size of what it is now. that box is waaaaaaaay too huge for that speaker and the little amount of power you are using.
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TEAM FEAR OF BASS Posts: 3611 | From: Toronto, On, Canada | Registered: Feb 2001
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quote:Originally posted by D-Bass: impedance is always going to be highest at the note at which your box is tuned. But, your box should have peak output 4-7Hz higher than tuning. the key is to get the box's peak to be at the vehicle's resonant frequency...not tuning the box at the vehicle's peak, but rather several Hertz lower
Yes, by tuning the box 5-10Hz (larger the box, smaller the freq step) lower than car res freq you can drop the impedance rise a bit.
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Alan and I have used .35s before. Alan when he had one 18 and myself with the six 12's. We ended up running .5 before finals two years ago. Ask Alan but I am think I am right I still have some of the 12 coils with it marked on them with marker.
Posts: 60 | From: Glenwood, GA | Registered: May 2007
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quote:Originally posted by murilo@soundigital.com.br:
quote:Originally posted by D-Bass: impedance is always going to be highest at the note at which your box is tuned. But, your box should have peak output 4-7Hz higher than tuning. the key is to get the box's peak to be at the vehicle's resonant frequency...not tuning the box at the vehicle's peak, but rather several Hertz lower
Yes, by tuning the box 5-10Hz (larger the box, smaller the freq step) lower than car res freq you can drop the impedance rise a bit.
if you are saying that a "proportionally" larger box, will have less change from tuning to peak output, suppose 3Hz difference...and a "proportionally" smaller box than "recommended" would have a large step up from tuning to peak output. such as tuned at 50, but peaking at 60...10Hz step
if that's what you're saying, i agree 100%
Posts: 5502 | From: Columbus, OH - formerly FL | Registered: Oct 2003
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So I have done some more testing and found that since changing subs, amp, and sealing the box to the trunk ALOT has changed in some very odd and unexpected ways.
So I did some testing with a single 10 in a .9 cu ft sealed box. This was with the 15 box in place and the trunk sealed off. I found that my RF is now 66 hz.
With playing a full series of sinewaves with the 15 I have found that my loudest note is 57hz (remember that box is tuned to 47hz). At low level testing it is a full 2 dbs louder than what I THOUGHT my peak was (53hz).
I have been told by someone with alot of experience that my loudest note will generally by 8-10 hz lower than my RF. From this testing that is what I am seeing. Does this make sense??
If my loudest note (57hz) is 8-10 db lower than my RF (66), I should try bringing my box tuning to about 4-5 hz lower than my peak note right? Which would mean I would want to shoot for around 52hz box tuning.
I thought that you always tune to peak right on RF and when the guy told me to shoot 8-10hz lower I thought he was crazy, but that seems to be what is happening from the tests. Also, why is my RF so freaking high? I always thought trunks were much lower. And yes I know I sound noobish. I've built prob hundreds of boxes but never actually tested or attempted to build a full on burp box.
-------------------- Cadence CMW6 Components Orion 4004 Component Amp Soundstream XXX-6500D for now AudioQue HDC3 15 Alum D1 151 from the trunk National Champion MidwestSPL Basic Trunk Posts: 93 | From: Des Moines Iowa | Registered: Mar 2009
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