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'[EE] Speaker + Guitar amp setup question'
Mario Mendes Jr.
I have 2 unused Becker speaker boxes (specs below), that I'd like to use to make a guitar amp box. I went to a local guitar shop to see if they sold just the amps, without the speakers and explained that I wanted to use it with these speakers and they told me I was going to ruin them. They couldn't really tell me why it would ruin them, just that it would happen. One of the guys said it had something to do with the fact they're 4 ohm speakers and not 8 (makes sense, since each is half the load a guitar amp is expected to drive), which led me to say, "just wire them in series", and again I got a "it does not work like that".
So my question for you guys is, can I wire them serially and hook them up to a 600 watts amp? I won't be using that much power in the house, but since the speakers can handle it, I'd like to have the ability to drive them that loudly should the opportunity present itself.
300 watts RMS
3 way crossover
15 inch woofer
> I have 2 unused Becker speaker boxes (specs below), that I'd like
> to use to make a guitar amp box. I went to a local guitar shop to
> see if they sold just the amps, without the speakers and explained
> that I wanted to use it with these speakers and they told me I was
> going to ruin them. They couldn't really tell me why it would ruin
> them, just that it would happen. One of the guys said it had
> something to do with the fact they're 4 ohm speakers and not 8
> (makes sense, since each is half the load a guitar amp is expected
> to drive), which led me to say, "just wire them in series", and again
> I got a "it does not work like that".
On the face of it that sounds just silly. Sure, I believe everything some
till jockey tells me (despite the fact that this is a specialty shop and
they *should* know what they're talking about). Home stereo
speakers could suffer in a band, due to the likely continuous loud
content and consequent coil heating and suspension fatigue. But you
could ruin them at home too by the same process, if the speaker isn't
designed for proper RMS power dissipation, both from the cone
and the coil
I've never met an amp yet, especially a guitar amp, that can't cope with
4 ohms. Any amp worth its salt can take the crap dished out to it by
musos. Being identical speakers I see no reason why you can't put
them in series. The only proviso is that they won't respond too well to
treble and that energy will be wasted in the coil. However, most music
energy is in the nether regions, ie bass. It might be an idea to install a
mid-range, tweeter and crossover network (a) to protect speakers
from unwanted/undesirable frequencies (b) to get a better sound
> So my question for you guys is, can I wire them serially and hook
> them up to a 600 watts amp?
See no real reason why. 600W is awfully loud in a house though. 20W
would be quite adequate. I've broken a window with a pair of 300W
15" Goodmans, probably quite similar to the ones you have. Yes, I did
do it deliberately, just to see if it could be done. It rattled itself to
Guitar speakers have stiff surrounds, home speakers typically don't.
Guitar speakers do not have crossovers and midranges and tweeters.
So you will tear the woofers to pieces, melt the midranges, and the
clipping will pop the tweeters.
And of course when one discusses watts and audio equipment, there are
multiple definitions, rarely intersecting. Very few speakers can
actually handle 300 watts, even for extremely short periods of time.
Becker, is that the same Becker that makes Mercedes stuff?
Mario Mendes Jr. wrote:
take a look at
which explains impedance matching. As the smart guys before me
said ( Jinx and Blick ), the guys at the guitar shop don't know what
are talking about. The main thing is that if you drive too much power
through the speakers, it is bye bye speakers. Play at a reasonable
level and have fun... crank it up to 11 and watch the cones fly.
Mario Mendes Jr. wrote:
> See no real reason why. 600W is awfully loud in a house
> though. 20W
> would be quite adequate. I've broken a window with a pair
> of 300W
> 15" Goodmans, probably quite similar to the ones you have.
> Yes, I did
> do it deliberately, just to see if it could be done. It
> rattled itself to
Fortunately, while my house does face in his general
direction, it's just over 5km away so I don't often have to
call the noise police.
Cedric Chang <cc <at> nope9.com> writes:
> which explains impedance matching. As the smart guys before me
Nobody uses impedance matched audio drivers because the boxes are too imperfect
and their impedance is all over the place. All currently used audio systems rely
on very low audio amplifier output impedance (a massive mismatch, sometimes
described as damping factor and in the 50dBs or higher even for cheap
amplifiers) to remove as much as possible of the bad influences of the speakers
and boxes. This includes guitar speakers. Exceptions are traditional telephone
earphone elements (600 Ohms), and certain very high power exponential horns
where the impedance mismatch cannot be tolerated (they would self destruct at
5kW+ power levels).
In small guitar amps sometimes a special speaker is allowed to add its 'color'
to the tone by deliberately not damping it too much. This used to be achieved in
valved amplifiers by sizing the output transformer and the feedback in certain
ways. It is not really possible to duplicate that with a modern semiconductor
amp, perhaps only by using a dsp to implement what is needed. And the special
speaker is still needed. Better modern guitar amps use all these tricks and
almost always special speakers (unonbatinibilium for normal mortals) in open
So, for the op, yes it is possible to build some guitar amps from your boxes,
probably the easiest way would be to buy a power amp block of 120-150W and add a
guitar preamp with effects. But it will not sound like the real thing.
On 29/12/2007, Mario Mendes Jr. <mmendes.com> wrote: piclist
A crossover "usually" attempts to to achieve a flat frequency response. This
can be at the expense of impedance.
Likely there are some serious impedance dips vs frequency etc....
Disconnect the crossover , wire directly to the woofer only for best
> And of course when one discusses watts and audio equipment,
> there are multiple definitions, rarely intersecting
The one I really dislike is PMPO
Santa brought my nephew a system for being a good (mostly) boy.
The box is marked in ENORMOUS writing 600W PMPO
Wow ! My ears are gonna bleed
But not so enormous writing 20W/ch RMS
BTW, I picked up a battered but working clock radio/cassette
from the last inorganic rubbish throw-out (no, not where I usually
shop, but a bargain's a bargain). Proudly and prominently marked
A.S.S. (Auto Stop System)
Good on ya Qualcraft
Like Homer buying the "new" Carnivale TV at the Outlet Mall in
Ogdenville - "It features two-pronged wall plug, pre-molded hand
grip well, durable outer casing to prevent fallapart..."
> Wow ! My ears are gonna bleed
> A.S.S. (Auto Stop System)
So how does 2008 look from your perspective? Ie, you being there before
the rest of us and all... er, well, don't ya know?
> So how does 2008 look from your perspective ?
Hmmm, so far it's very dark. I don't think that will last too
long though. It was like this about the same time yesterday
and it had brightened up considerably by the time I got out
of bed. And I can hear several houses finding out the
difference between PMPO and RMS
On Sat, 29 Dec 2007 15:19:27 -0500
"Mario Mendes Jr." <mmendes.com> wrote: piclist
> "just wire them in series", and again I got a "it does not work like
The only objection (apart from the noise level), is that if you use two
boxes in series, you'll create a lot of acoustic interferences. Not an
amplifier or box problem...
Example, at 1000 Hz, wavelength is only 33 cm, so you'll have zones where
1000Hz can't be heard and others where it'll sum. With most music you
won't hear the difference because of the complex spectrum, but with clean
sine sound you'll surely find changes according to where you sit (and
possible sine-generating instruments like xylophones etc.)
'[EE] Speaker + Guitar amp setup question'
Mario, I missed the '3 way crossover' line and thought you
were talking about simply two 15" woofers. That makes a
difference because the amp isn't seeing speakers, it's seeing
crossovers. In that case it would be better to break it down
(figuratively) and take another look. Maybe that the woofers
can be in series, likewise the mid-ranges and tweeters. Then
put a crossover as a front end. Presumably though a single
crossover won't be rated for 600W, although you have helped
a little by putting speakers in series. I don't know if you could
successfully series or parallel whole crossovers units, given
that the designer probably didn't have that in mind. You have
several options - separate amps for whole box or individual
speaker, re-design crossover etc. It largely depends on what
power you're planning to generally use (eg is one 300W
cabinet often enough ?) and how much re-wiring fuss if you
want to switch between dual roles as home and performance
> I have 2 unused Becker speaker boxes (specs below)
> 300 watts RMS
> 4 ohm
> 3 way crossover
> 15 inch woofer
John Coppens wrote:
> On Sat, 29 Dec 2007 15:19:27 -0500
> "Mario Mendes Jr." <mmendes.com> wrote: piclist
>> "just wire them in series", and again I got a "it does not work like
> The only objection (apart from the noise level), is that if you use two
> boxes in series, you'll create a lot of acoustic interferences. Not an
> amplifier or box problem...
And for the record, not a problem with /series/ wiring either... the same
problem happens with parallel wiring.
> > The only objection (apart from the noise level), is that if you
> > use two boxes in series, you'll create a lot of acoustic
> > interferences. Not an amplifier or box problem...
> And for the record, not a problem with /series/ wiring either...
> the same problem happens with parallel wiring
At one time I had a big bass reflex W bin and a 300W amp. Our
guitarist would scowl at me - although it was much easier for him
to move his poofy combo so his sound didn't have to travel across
my sound - because my bass bin disturbed the air so much it made
his guitar sound like it was underwater. Which might not have been
a bad place for it sometimes. It was quite easy to blow a lighter out
with a punch of air from a port
Mario Mendes Jr.
Thanks for all of the responses. From quite a few of the posts I can tell I
won't end up with a very good sounding system, so I probably won't
cannibalize the boxes.... yet, I may change my mind at some point.
From: "Gerhard Fiedler" <connectionbrazil.com> lists
Sent: Wednesday, January 02, 2008 4:26 PM
To: <mit.edu> piclist
Subject: Re: [EE] Speaker + Guitar amp setup question
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