2 way passive crossover?

[Matt]

Hey all.

Its been about 10+ years since I've messed with a passive installation of subs,
mids and high pass drivers.

A friend of mine has a single two channel G&S amplifier, 4 8" Rockford subs
(brand new) and MB Quart 6" midbass drivers with 1" highpass drivers. Ive been
looking for a 2-Way passive crossover that would cut the subs at 100-120hz @
12db but so far all the two way crossovers ive found only cross the midpass and
highpass drivers. Back in my car installation days driving subs at full range
was a no-no. It seems as though when installing subs into a bandpass (not sure
of which order) its not only OK but your supposed to drive subs at full range??
I dont really fell like building a bandpass though. I really wanted to build a
single chamber ported box.

Anyway, my best case cenario would be to find a two way passive crossover for
this guys install. Cross the lowpass @ 100 or so and the rest from there would
go to the mid and highpass drivers. I guess I can build the damn things out of
Bass coils and caps but thats another project!

Any help would be great.

BTW, Im not interested in telling him to "buy a new amp". Its not going to
happen.


Matt



M and M Electronics
6661 Stanford Ranch Road
Suite F, PMB 105
Rocklin Ca 95677
916-275-5871

[Kevin Murray]

How about wiring the component set directly to the amp and using a dedicated
subwoofer filter for the subs? This way you save the unnecessary cost of a
two-way crossover. Have a listen and if you don't like the way things are, then
switch to the crossover set-up later. If you are having trouble finding a
crossover (or sub filter for that matter) most car audio shops can sell you the
required parts for your particular load impedance.

Kevin Murray


"Matt" > wrote in message
...
> Hey all.
>
> Its been about 10+ years since I've messed with a passive installation of
subs,
> mids and high pass drivers.
>
> A friend of mine has a single two channel G&S amplifier, 4 8" Rockford subs
> (brand new) and MB Quart 6" midbass drivers with 1" highpass drivers. Ive been
> looking for a 2-Way passive crossover that would cut the subs at 100-120hz @
> 12db but so far all the two way crossovers ive found only cross the midpass
and
> highpass drivers. Back in my car installation days driving subs at full range
> was a no-no. It seems as though when installing subs into a bandpass (not sure
> of which order) its not only OK but your supposed to drive subs at full
range??
> I dont really fell like building a bandpass though. I really wanted to build a
> single chamber ported box.
>
> Anyway, my best case cenario would be to find a two way passive crossover for
> this guys install. Cross the lowpass @ 100 or so and the rest from there would
> go to the mid and highpass drivers. I guess I can build the damn things out of
> Bass coils and caps but thats another project!
>
> Any help would be great.
>
> BTW, Im not interested in telling him to "buy a new amp". Its not going to
> happen.
>
>
> Matt
>
>
>
> M and M Electronics
> 6661 Stanford Ranch Road
> Suite F, PMB 105
> Rocklin Ca 95677
> 916-275-5871
>

[Matt]

>How about wiring the component set directly to the amp and using a dedicated
>subwoofer filter for the subs?

I thought about that too. The only problem I can see is that the crossover that
comes with the mid and highpass setup tosses 20-3.5k at the Midbass driver. I
dont want that driver to get anything lower then 100 just to keep it from
blowing up.

The amp the guy has can really pack a punch. It will fry those 6" drivers in no
time.


Matt



M and M Electronics
6661 Stanford Ranch Road
Suite F, PMB 105
Rocklin Ca 95677
916-275-5871

[MZ]

> >How about wiring the component set directly to the amp and using a
dedicated
> >subwoofer filter for the subs?
>
> I thought about that too. The only problem I can see is that the crossover
that
> comes with the mid and highpass setup tosses 20-3.5k at the Midbass
driver. I
> dont want that driver to get anything lower then 100 just to keep it from
> blowing up.
>
> The amp the guy has can really pack a punch. It will fry those 6" drivers
in no
> time.

But it's easier (ie. much cheaper) to use a passive high pass for the
midbass drivers than a passive low pass for the sub.

[Kevin Murray]

Would you be comfortable modifying the midbass section of the crossover to a
bandpass design? The addition of a simple cap would give you a high pass
anywhere you want at a 6dB rolloff. 150Hz @ 6dB/octave should suffice to protect
the midbasses. Again any installer should be able to help you with this.

"Matt" > wrote in message
...
> >How about wiring the component set directly to the amp and using a dedicated
> >subwoofer filter for the subs?
>
> I thought about that too. The only problem I can see is that the crossover
that
> comes with the mid and highpass setup tosses 20-3.5k at the Midbass driver. I
> dont want that driver to get anything lower then 100 just to keep it from
> blowing up.
>
> The amp the guy has can really pack a punch. It will fry those 6" drivers in
no
> time.
>
>
> Matt
>
>
>
> M and M Electronics
> 6661 Stanford Ranch Road
> Suite F, PMB 105
> Rocklin Ca 95677
> 916-275-5871
>

[Kevin Murray]

Not sure what you're getting at Mark. Unless he decides to drive the separates
with deck power he will need a passive filter for the sub. I believe he intends
to full-range the amp and do all his filtering afterwards.

"MZ" wrote:
<snip>
> But it's easier (ie. much cheaper) to use a passive high pass for the
> midbass drivers than a passive low pass for the sub.
>
>

[MZ]

> Not sure what you're getting at Mark. Unless he decides to drive the
separates
> with deck power he will need a passive filter for the sub. I believe he
intends
> to full-range the amp and do all his filtering afterwards.

Yeah, I just reread that and figured out what he's trying to do.

The easiest, best, and cheapest option is to do something he already said he
wouldn't do. :)

[MZ]

> Would you be comfortable modifying the midbass section of the crossover to
a
> bandpass design? The addition of a simple cap would give you a high pass
> anywhere you want at a 6dB rolloff. 150Hz @ 6dB/octave should suffice to
protect
> the midbasses. Again any installer should be able to help you with this.

"Should" being the operative word...

[Matt]

>> Would you be comfortable modifying the midbass section of the crossover to
>a
>> bandpass design? The addition of a simple cap would give you a high pass
>> anywhere you want at a 6dB rolloff. 150Hz @ 6dB/octave should suffice to
>protect
>> the midbasses. Again any installer should be able to help you with this.
>
>"Should" being the operative word...
>
Maybe Im not asking the question right.

I want the midpass to start around 100-120hz. I was also asking if I should (or
can) drive the subs at full range. I'd be cool with running a 2-way crossover
that would output 130 and below to the sub and 120 and above to the
Mid/highpass and just put caps and coils on the tweets to cross them at 3500 or
something. I used to be able to buy boards with the caps and coils on them that
did just that. All I can find now are 2 way crossovers for Mids and highs.

Like I said, in my installing days we would have put a 100mf cap on the
midbass, a 5.6 or 6.1mh coil on the subs and called it quits. If we wanted to
get fancy we might even add the extra parts to the crossovers to make them 12db
per octave but 6 worked fine.

The last time I worked "professionally" in a car stereo shop Linear (sp?) was
still around, Rockford was JUST getting into MOSFET and Orion was the
mac-daaddy of power. see, its been a while...


Matt



M and M Electronics
6661 Stanford Ranch Road
Suite F, PMB 105
Rocklin Ca 95677
916-275-5871

[MZ]

> Maybe Im not asking the question right.
>
> I want the midpass to start around 100-120hz. I was also asking if I
should (or
> can) drive the subs at full range. I'd be cool with running a 2-way
crossover
> that would output 130 and below to the sub and 120 and above to the
> Mid/highpass and just put caps and coils on the tweets to cross them at
3500 or
> something. I used to be able to buy boards with the caps and coils on them
that
> did just that. All I can find now are 2 way crossovers for Mids and highs.
>
> Like I said, in my installing days we would have put a 100mf cap on the
> midbass, a 5.6 or 6.1mh coil on the subs and called it quits. If we wanted
to
> get fancy we might even add the extra parts to the crossovers to make them
12db
> per octave but 6 worked fine.
>
> The last time I worked "professionally" in a car stereo shop Linear (sp?)
was
> still around, Rockford was JUST getting into MOSFET and Orion was the
> mac-daaddy of power. see, its been a while...

It's not generally the best idea to run your sub full-range. But if it's in
the trunk, I suppose it could suffice for a simple budget installation.
Performance will suffer though, and the amp will run hotter. If you want to
determine what size caps and inductors to use, visit passivecrossovers.com.

[Kevin Murray]

I think I see what you're asking. "Is it ok to do less than the required minimum
for 'decent' sound?"
I assumed in my previous posts that you already had a crossover that came with
the component set. I was suggesting that you modify this existing crossover to
suit your mid/high needs. If you have no existing crossover for the component
set, you will have to build/buy one. I urge you to research crossover design a
little more on the site Mark provided. Then you can choose whatever crossover
points make you happy. You might be surprised what you can accomplish for little
money.

Then you have to deal with your sub. If you want to really go cheap with the sub
you could try running it full range since it wont cost you a thing. If it's in
the trunk, like Mark said, you may get by with that set-up. Worst case you need
to add a filter later. I think that if you expect half-way decent sound from
your ported box you will have to low-pass filter it.

I realise the importance of budget but somewhere you need to make concessions.
All that expensive gear will go to waste if you compromise the install for a few
dollars.


"Matt" > wrote in message
...
> >> Would you be comfortable modifying the midbass section of the crossover to
> >a
> >> bandpass design? The addition of a simple cap would give you a high pass
> >> anywhere you want at a 6dB rolloff. 150Hz @ 6dB/octave should suffice to
> >protect
> >> the midbasses. Again any installer should be able to help you with this.
> >
> >"Should" being the operative word...
> >
> Maybe Im not asking the question right.
>
> I want the midpass to start around 100-120hz. I was also asking if I should
(or
> can) drive the subs at full range. I'd be cool with running a 2-way crossover
> that would output 130 and below to the sub and 120 and above to the
> Mid/highpass and just put caps and coils on the tweets to cross them at 3500
or
> something. I used to be able to buy boards with the caps and coils on them
that
> did just that. All I can find now are 2 way crossovers for Mids and highs.
>
> Like I said, in my installing days we would have put a 100mf cap on the
> midbass, a 5.6 or 6.1mh coil on the subs and called it quits. If we wanted to
> get fancy we might even add the extra parts to the crossovers to make them
12db
> per octave but 6 worked fine.
>
> The last time I worked "professionally" in a car stereo shop Linear (sp?) was
> still around, Rockford was JUST getting into MOSFET and Orion was the
> mac-daaddy of power. see, its been a while...
>
>
> Matt
>
>
>
> M and M Electronics
> 6661 Stanford Ranch Road
> Suite F, PMB 105
> Rocklin Ca 95677
> 916-275-5871
>

[Matt]

>I realise the importance of budget but somewhere you need to make
>concessions.

I never said anything about the install being held back by budget. The guy just
wants to use what he has.

For the record...

1 G&S P500 (I think thats the model)
1 Kenwood... Blah blah head unit
4 pairs of MB Quart 6" midbass and the tweeters that came with them AND the
crossovers that came with them.
4 Rockford SP88's

OK, he lost the Bass coils when he tossed the box that the woofers were in.
From the looks of crossovers that came with the MB Quarts they dont notch out
frequencies below 100hz so that would mean that they were driven at
20hz-whatever they cut at. I dont want to run the subs at full range but read
that 7th order bandpasses could get away with this.

My absolute BEST case cenario would be to find 2 2way crossovers that did the
following...

Provide the Subs with 20hz-120hz@12db and 120HZ and above to the Mid/Highpass
which I would then run into the MB crossovers.

Thanks for all the input!


Matt



M and M Electronics
6661 Stanford Ranch Road
Suite F, PMB 105
Rocklin Ca 95677
916-275-5871

[Kevin Murray]

"Matt" wrote:
<snip>
> My absolute BEST case cenario would be to find 2 2way crossovers that did the
> following...
>
> Provide the Subs with 20hz-120hz@12db and 120HZ and above to the Mid/Highpass
> which I would then run into the MB crossovers.

You can do this. I don't think there is a pre-fab crossover for your
application. Speak with a car audio installer about the parts you need for it.
Ask him about a subwoofer filter and perhaps simply modifying the existing MB
Quart crossovers to bandpass the midbass (ie:120-3500). There's no need to build
another crossover.
My understanding was that your friend wanted a "single chamber ported box". I'm
not sure how bandpass enclosures apply here. Some people are satisfied with no
filter on a bandpass. I find that the highs still escape, with some added
reverb. I suppose it would be fine if the box was in a trunk. Hope that clears
things up for you.

[Matt]

>My understanding was that your friend wanted a "single chamber ported box".

that was just another option knocking around in my head.

I had a 7th order bandpass with two JL 10's in it a long time ago. I ran the
thing full range and it seemed to be fine. Ive just never been a big fan of
running subs at full range. Midrange audio out of a sub sounds REAL bad to me.
Almost as bad at those big ole' nasty horn tweeters...

thanks for the input! Ill work on modifying the MB crossovers and toss coils on
the subs. That sounds like the thing to do.


Matt



M and M Electronics
6661 Stanford Ranch Road
Suite F, PMB 105
Rocklin Ca 95677
916-275-5871

[Daniel Snooks]

Matt wrote
> that was just another option knocking around in my head.
>
> I had a 7th order bandpass with two JL 10's in it a long time ago. I ran
the
> thing full range and it seemed to be fine. Ive just never been a big fan
of
> running subs at full range. Midrange audio out of a sub sounds REAL bad to
me.
> Almost as bad at those big ole' nasty horn tweeters...
>
> thanks for the input! Ill work on modifying the MB crossovers and toss
coils on
> the subs. That sounds like the thing to do.

Maybe I am oversimplifying this, but can't you just put 100uF caps inline
with the existing crossovers to highpass the components? I don't see why the
existing crossovers have to be "modified".
Also, as far as the subs are concerned, you only need one coil unless you
are planning on using more then one channel to run them. The way I see it
you need 4 100uF bi-polar caps, and a 6mh coil.
Am I wrong?

[Matt]

>The way I see it
>you need 4 100uF bi-polar caps, and a 6mh coil.
>Am I wrong?

Nope, your right on the money. Ive been having a hell of a time finding them
which is why I started this thread.

I tried searching for Bass Coil in google. It gave me a few hits but nbothing
to obvious. I didnt bother with the caps after my search for the coils failed.

If you guys could point me to an online source that would be great. The few car
stereo stors Ive tried in my area didnt have the stuff. One even asked me what
a bass coil was... eh...

Thanks!


Matt



M and M Electronics
6661 Stanford Ranch Road
Suite F, PMB 105
Rocklin Ca 95677
916-275-5871

[Scott Gardner]

On 26 Apr 2004 07:14:22 GMT, (Matt) wrote:

>>The way I see it
>>you need 4 100uF bi-polar caps, and a 6mh coil.
>>Am I wrong?
>
>Nope, your right on the money. Ive been having a hell of a time finding them
>which is why I started this thread.
>
>I tried searching for Bass Coil in google. It gave me a few hits but nbothing
>to obvious. I didnt bother with the caps after my search for the coils failed.
>
>If you guys could point me to an online source that would be great. The few car
>stereo stors Ive tried in my area didnt have the stuff. One even asked me what
>a bass coil was... eh...
>
>Thanks!
>
>
>Matt
>

They may have known what you meant, but just never heard the term
"bass coil". The part you're looking for is called an "inductor", and
any number of electronics parts houses carry them. Some of the larger
values (like what you would need for a very low crossover point) may
be harder to find. I'll look around and see if I can find a source
for 6mH inductors.

Scott Gardner

[Scott Gardner]

On 26 Apr 2004 07:14:22 GMT, (Matt) wrote:

>>The way I see it
>>you need 4 100uF bi-polar caps, and a 6mh coil.
>>Am I wrong?
>
>Nope, your right on the money. Ive been having a hell of a time finding them
>which is why I started this thread.
>
>I tried searching for Bass Coil in google. It gave me a few hits but nbothing
>to obvious. I didnt bother with the caps after my search for the coils failed.
>
>If you guys could point me to an online source that would be great. The few car
>stereo stors Ive tried in my area didnt have the stuff. One even asked me what
>a bass coil was... eh...
>
>Thanks!
>
>
>Matt
>


Found some. PartsExpress.com has some 6mH air-core inductors for use
in crossovers. Power handling is 180 watts - I don't know if that's
enough. Here's the link to the PartsExpress part.

http://tinyurl.com/2ke8p

Scott Gardner

[Kevin Murray]

"Daniel Snooks" wrote:
<snip>
> Maybe I am oversimplifying this, but can't you just put 100uF caps inline
> with the existing crossovers to highpass the components? I don't see why the
> existing crossovers have to be "modified".
> Also, as far as the subs are concerned, you only need one coil unless you
> are planning on using more then one channel to run them. The way I see it
> you need 4 100uF bi-polar caps, and a 6mh coil.
> Am I wrong?
>

Essentially what I was saying. I'd prefer to add the cap to the existing
crossovers to keep things clean and make troubleshooting easier should checking
connections become necessary. I'd personally go with a higher order, like 12dB
which would make things a little messier otherwise. I'm not going to check your
math on the component values but it sounds ballpark.

I have access to lots of free motor wire so I like to wind my own coils. I
wanted to suggest that anyone should research doing things themselves in case
they too can save some money on their install. It adds a bit more of the pride
factor too.

[Matt]

>Here's the link to the PartsExpress part.

BINGO! Thats exactly what I needed. Thank you very much!


Matt



M and M Electronics
6661 Stanford Ranch Road
Suite F, PMB 105
Rocklin Ca 95677
916-275-5871

[MZ]

This place has up to 5mH...

They have even larger if you're willing to pay the extra dough.

http://www.speakercity.com/xover/coils.shtml

--
Mark
remove "remove" and "spam" to reply


"Matt" > wrote in message
...
> >Here's the link to the PartsExpress part.
>
> BINGO! Thats exactly what I needed. Thank you very much!
>
>
> Matt
>
>
>
> M and M Electronics
> 6661 Stanford Ranch Road
> Suite F, PMB 105
> Rocklin Ca 95677
> 916-275-5871
>