Configuring HU crossover points
Thread Starter
Pro
Joined: Mar 1999
Posts: 535
Likes: 1
From: GA
Configuring HU crossover points
Can anyone give me some advice on setting the crossover points on my Alpine CDA_7998?
I'm driving MB Quart QSD216s off a JL 300/2 and a 10W2-v2 in a stealthbox off a JL 250. MQ Quart specs say frequency response is 35 - 32K. I couldn't find anything on the 10W2.
Where should I be setting the crossover filter points? What about the slope? Heck, I could probably use a general system tuning tutorial.
:jester
I'm driving MB Quart QSD216s off a JL 300/2 and a 10W2-v2 in a stealthbox off a JL 250. MQ Quart specs say frequency response is 35 - 32K. I couldn't find anything on the 10W2.
Where should I be setting the crossover filter points? What about the slope? Heck, I could probably use a general system tuning tutorial.
:jester
Team Owner
Joined: Feb 2000
Posts: 51,504
Likes: 6
From: Sacramento CA
Re: Configuring HU crossover points (mfrnka)
I like a 12db slope on components, and 12db slope on subs that do well above 80hz. For subs that dont, I like a 24db slope. I would go with 12 with the JL sub
Id put them at 70hz...
Id put them at 70hz...
Melting Slicks
Joined: Jan 2002
Posts: 2,682
Likes: 0
From: Atlanta GA
Re: Configuring HU crossover points (mfrnka)
Can anyone give me some advice on setting the crossover points on my Alpine CDA_7998?
I'm driving MB Quart QSD216s off a JL 300/2 and a 10W2-v2 in a stealthbox off a JL 250. MQ Quart specs say frequency response is 35 - 32K. I couldn't find anything on the 10W2.
Where should I be setting the crossover filter points? What about the slope? Heck, I could probably use a general system tuning tutorial.
:jester
I'm driving MB Quart QSD216s off a JL 300/2 and a 10W2-v2 in a stealthbox off a JL 250. MQ Quart specs say frequency response is 35 - 32K. I couldn't find anything on the 10W2.
Where should I be setting the crossover filter points? What about the slope? Heck, I could probably use a general system tuning tutorial.
:jester
I discovered that the internal crossovers on the Alpine is not enough. There is still some "bleed" into the cut off frequencies. You really need to get an audio test CD. I've got one you can borrow if you like. :cheers:
A good rule of thumb is 80Hz high and low pass. However, the Alpine crossovers set at 80 Hz will allow the components to play down to about 60Hz and the sub to play up to about 100Hz. Not good.
:crazy:
Team Owner
Joined: Feb 2000
Posts: 51,504
Likes: 6
From: Sacramento CA
Re: Configuring HU crossover points (leolufse)
I think it has to do with the slope. 12DB gives you a good fall off, keeps the low frequencies low enough. Set it to 24db to be "safe" if you'd like...
12DB on my amp at 80hz sounds exactly like 12db on the HU at 80hz.
[Modified by Kale, 7:07 PM 7/11/2003]
12DB on my amp at 80hz sounds exactly like 12db on the HU at 80hz.
[Modified by Kale, 7:07 PM 7/11/2003]
Drifting
Joined: Jun 2002
Posts: 1,340
Likes: 1
From: hamilton nj "Life's tough......It's even tougher if you're stupid."-John Wayne
Re: Configuring HU crossover points (leolufse)
-------------------------------------------------
You really need to get an audio test CD.
-------------------------------------------------
leolufse, the audio test Cd you mentioned, is there a special one or is one better than another? Where do you find them?
:cheers:
[Modified by budmont, 10:36 PM 7/11/2003]
You really need to get an audio test CD.
-------------------------------------------------
leolufse, the audio test Cd you mentioned, is there a special one or is one better than another? Where do you find them?
:cheers:
[Modified by budmont, 10:36 PM 7/11/2003]
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Re: Configuring HU crossover points (mfrnka)
ugh... I have the 7998 head, too... and the cross points are just a pain.
I ended up negating them and using the linear xover's on the amp.
2 xovers just confuse things.
I ended up negating them and using the linear xover's on the amp.
2 xovers just confuse things.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Re: Configuring HU crossover points (budmont)
-------------------------------------------------
You really need to get an audio test CD.
-------------------------------------------------
leolufse, the audio test Cd you mentioned, is there a special one or is one better than another? Where do you find them?
:cheers:
You really need to get an audio test CD.
-------------------------------------------------
leolufse, the audio test Cd you mentioned, is there a special one or is one better than another? Where do you find them?
:cheers:
I do know that IASCA (sound off organization) has a CD you can get. but it is rather pricy.
Thread Starter
Pro
Joined: Mar 1999
Posts: 535
Likes: 1
From: GA
Re: Configuring HU crossover points (bogus)
Thanks for the feedback everyone.
Using a the crossover on the amp for the components AND the amp for the sub still gives me two crossovers to fool with, right?
Lars - I see your point about the cutoffs not being clean and think it is a function of this slope business. The higher the slope the faster and more drastic the cutoff. 24db is as aggressive as it gets, but is still not hard cutoff point at a particular frequency. Anyone know how the cutoff's on the amps work? Are they equivalent to the 24 db slope or something even more more aggressive. Setting the high and low pass filters with this sloped cutoff, it seems there will always be some overlap/bleed. Either that or you set one at 80 and one at 60 and you're losing some sound in the 60 - 80 range - not good.
Is it that big of a problem to have a small range of frequencies being output by the components and the sub? Can you possibly tone down the overlapped frequencies with the EQ? Then again, I'd guess the HU EQ isn't granular enough to manipulate just the 60 - 80 range.
[Modified by mfrnka, 11:57 PM 7/12/2003]
ugh... I have the 7998 head, too... and the cross points are just a pain.
I ended up negating them and using the linear xover's on the amp.
2 xovers just confuse things.
I ended up negating them and using the linear xover's on the amp.
2 xovers just confuse things.
Lars - I see your point about the cutoffs not being clean and think it is a function of this slope business. The higher the slope the faster and more drastic the cutoff. 24db is as aggressive as it gets, but is still not hard cutoff point at a particular frequency. Anyone know how the cutoff's on the amps work? Are they equivalent to the 24 db slope or something even more more aggressive. Setting the high and low pass filters with this sloped cutoff, it seems there will always be some overlap/bleed. Either that or you set one at 80 and one at 60 and you're losing some sound in the 60 - 80 range - not good.
Is it that big of a problem to have a small range of frequencies being output by the components and the sub? Can you possibly tone down the overlapped frequencies with the EQ? Then again, I'd guess the HU EQ isn't granular enough to manipulate just the 60 - 80 range.
[Modified by mfrnka, 11:57 PM 7/12/2003]
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Re: Configuring HU crossover points (mfrnka)
Thanks for the feedback everyone.
ugh... I have the 7998 head, too... and the cross points are just a pain.
I ended up negating them and using the linear xover's on the amp.
2 xovers just confuse things.
Using a the crossover on the amp for the components AND the amp for the sub still gives me two crossovers to fool with, right?
ugh... I have the 7998 head, too... and the cross points are just a pain.
I ended up negating them and using the linear xover's on the amp.
2 xovers just confuse things.
Using a the crossover on the amp for the components AND the amp for the sub still gives me two crossovers to fool with, right?
Thread Starter
Pro
Joined: Mar 1999
Posts: 535
Likes: 1
From: GA
Re: Configuring HU crossover points (bogus)
allow me to clarify... 2 crossovers in the same line... meaning, the xover on the head unit was causing confusion with the xover on the amp. er, more accuratly, confusing me. :D
[Modified by mfrnka, 11:08 PM 7/13/2003]
Melting Slicks
Joined: Jan 2002
Posts: 2,682
Likes: 0
From: Atlanta GA
Re: Configuring HU crossover points (mfrnka)
Michael:
Here is the test CD I bought. Got it on ebay for $10.
http://cgi.ebay.com/ws/eBayISAPI.dll...category=23794
[Modified by leolufse, 11:13 AM 7/14/2003]
Here is the test CD I bought. Got it on ebay for $10.
http://cgi.ebay.com/ws/eBayISAPI.dll...category=23794
[Modified by leolufse, 11:13 AM 7/14/2003]
Thread Starter
Pro
Joined: Mar 1999
Posts: 535
Likes: 1
From: GA
Re: Configuring HU crossover points (leolufse)
Thanks Lars.
I've been toying w/ the xovers a bit and although I think crossing them at 80 Hz or something like 60 and 100 is the "right" think to do, it's not sounding very good.
Cutting the lows to the MB Quarts really drops the overall bass level. Both amp gains are all the way up. The HU volume maxes out at "35" and although it's LOUD, everthing sounds good. The sub just doesn't seem to really start pumpin' until the volume level gets to 28 - 30. If I recall my old car stereo tech, this was the purpose of the "loudness" button - to boost the low volume bass and roll it back as the overall volume increased. As it stands now, I'm doing this manually by adjust the static bass boost. As you can imagine, this gets old and I'm sure there is a better way to do this.
I've been toying w/ the xovers a bit and although I think crossing them at 80 Hz or something like 60 and 100 is the "right" think to do, it's not sounding very good.
Cutting the lows to the MB Quarts really drops the overall bass level. Both amp gains are all the way up. The HU volume maxes out at "35" and although it's LOUD, everthing sounds good. The sub just doesn't seem to really start pumpin' until the volume level gets to 28 - 30. If I recall my old car stereo tech, this was the purpose of the "loudness" button - to boost the low volume bass and roll it back as the overall volume increased. As it stands now, I'm doing this manually by adjust the static bass boost. As you can imagine, this gets old and I'm sure there is a better way to do this.
Team Owner
Joined: Feb 2000
Posts: 51,504
Likes: 6
From: Sacramento CA
Re: Configuring HU crossover points (mfrnka)
Loud also causes massive distortion, sometimes you cant hear the fronts distorting because the sub over powers it.
Here's what I did on my 7998
VOLUMe 22 = MAX VOLUME
Set front amp to proper gain level at 22 Volume.
Set Subwoofer Level at 10
Set sub amp to proper gain level at "Sub level 10" and overall volume "22"
When listening to the stereo at 18, I raise the sub level to 15. This doesnt add distortion or coloration like "loud" does.
Here's what I did on my 7998
VOLUMe 22 = MAX VOLUME
Set front amp to proper gain level at 22 Volume.
Set Subwoofer Level at 10
Set sub amp to proper gain level at "Sub level 10" and overall volume "22"
When listening to the stereo at 18, I raise the sub level to 15. This doesnt add distortion or coloration like "loud" does.
