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Home > Archive > Electrical Engineering > June 2006 > Capacitor values
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| PanHandler 2006-06-12, 1:21 pm |
| I'm using a Pyramid 35 Amp, 12-15 Volt power supply for my 'portable' sound
system. See here: http://flickr.com/photos/43996336@N00/page4/ , and it's
been recommended that I install an electrolytic across the supply output.
The 4 channel, 12Volt amplifier is 'rated' at 350 Watts/channel into 2 Ohms.
I don't question the recommendation, but would like to be certain of the cap
values.
TIA
Joe Arnold
- - - - - - - - - - - - - - - - - - -
Easy's getting harder everyday
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| Palindr☻me 2006-06-12, 2:21 pm |
| PanHandler wrote:
> I'm using a Pyramid 35 Amp, 12-15 Volt power supply for my 'portable' sound
> system. See here: http://flickr.com/photos/43996336@N00/page4/ , and it's
> been recommended that I install an electrolytic across the supply output.
> The 4 channel, 12Volt amplifier is 'rated' at 350 Watts/channel into 2 Ohms.
> I don't question the recommendation, but would like to be certain of the cap
> values.
How about one of these?
http://www.maplin.co.uk/Module.aspx...FAQS=Y&doy=12m6
--
Sue
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| Palindr☻me 2006-06-12, 3:21 pm |
| PanHandler wrote:
> "Palindr?me" <me9@privacy.net> wrote in message
> news:128r7kb78rb0105@corp.supernews.com...
>
>
>
> Wow - that's about $150. US
Well, I assumed that you wanted something that would make a significant
difference.
4 channels at 350W is 1400W, well over 100A at 12v. Your power supply is
only rated at 35A surge, so isn't going to cope with anything like full
output without sagging - even driving just one channel, come to that.
So, if you are trying to improve the transient handling situation by
adding a capacitor, it has to be a really big one....You still won't be
able to drive your amplifiers to anything even remotely approaching full
load, but will be able to get a lot more dynamic range.
--
Sue
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| PanHandler 2006-06-12, 3:21 pm |
|
"Palindr?me" <me9@privacy.net> wrote in message
news:128r99q65elig7a@corp.supernews.com...
> Well, I assumed that you wanted something that would make a significant
> difference.
>
> 4 channels at 350W is 1400W, well over 100A at 12v. Your power supply is
> only rated at 35A surge, so isn't going to cope with anything like full
> output without sagging - even driving just one channel, come to that. So,
> if you are trying to improve the transient handling situation by adding a
> capacitor, it has to be a really big one....You still won't be able to
> drive your amplifiers to anything even remotely approaching full load, but
> will be able to get a lot more dynamic range.
Thanks for the attention Sue. I just didn't expect to spend that much. What
about 2 or 3 mfd? :-)
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| Palindr☻me 2006-06-12, 4:21 pm |
| PanHandler wrote:
> "Palindr?me" <me9@privacy.net> wrote in message
> news:128r99q65elig7a@corp.supernews.com...
>
>
>
> Thanks for the attention Sue. I just didn't expect to spend that much. What
> about 2 or 3 mfd? :-)
>
>
A 2mfd capacitor at 12v holds 0.5 x 0.000002 x 12 x 12 joules. i.e
0.0001 joules. It can deliver 1400W for 0.0001/1400 seconds. i.e about
a tenth of a microsecond. Peeing on a forest fire springs to mind...
--
Sue
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| Derek ^ 2006-06-12, 4:21 pm |
| On Mon, 12 Jun 2006 19:30:42 +0100, Palindr?me <me9@privacy.net>
wrote:
>A 2mfd capacitor at 12v holds 0.5 x 0.000002 x 12 x 12 joules. i.e
>0.0001 joules. It can deliver 1400W for 0.0001/1400 seconds. i.e about
>a tenth of a microsecond. Peeing on a forest fire springs to mind...
Indeed. But a 1 farad capacitor is only 500,000 times better. That
translates to about a 20th of a second.
Would help with isolated transient peaks.
How about floating a car/leisure battery across the psu output. taking
the necessary precautions about the psu voltage and whether or not it
would tolerate being back fed with DC
DG
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| Palindr☻me 2006-06-12, 5:21 pm |
| Derek ^ wrote:
> On Mon, 12 Jun 2006 19:30:42 +0100, Palindr?me <me9@privacy.net>
> wrote:
>
>
>
>
>
> Indeed. But a 1 farad capacitor is only 500,000 times better. That
> translates to about a 20th of a second.
It will produce a discernable improvement, especially at lower power
settings. Bigger would be better but this is about as big as they
come... Not forgetting that the next mains half cycle will be along,
when it comes to energy demands...
>
> Would help with isolated transient peaks.
And reduce 50/100Hz hum quite a bit.
>
> How about floating a car/leisure battery across the psu output. taking
> the necessary precautions about the psu voltage and whether or not it
> would tolerate being back fed with DC
Yep, the mains supply the OP mentions can provide about 300W. Adding a
couple of 6v 120AH batteries would give many hours of volume levels loud
enough to wake the dead..
His amps almost certainly have inverters built in - to up the voltage to
the power stages to say 40v. You only get around 20W max with 12v into 2
ohms. So sticking a deep discharge battery as the power input and
sticking more C across the pa power rails is probably the best bet.
--
Sue
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| PanHandler 2006-06-12, 6:21 pm |
|
"Palindr?me" <me9@privacy.net> wrote in message
news:128rcm4use5g7f@corp.supernews.com...
> A 2mfd capacitor at 12v holds 0.5 x 0.000002 x 12 x 12 joules. i.e 0.0001
> joules. It can deliver 1400W for 0.0001/1400 seconds. i.e about a tenth
> of a microsecond. Peeing on a forest fire springs to mind...
LOL - Well I hadda ask! What are the specs @ 1 mfd?
Joe
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| Palindr☻me 2006-06-12, 6:21 pm |
| PanHandler wrote:
> "Palindr?me" <me9@privacy.net> wrote in message
> news:128rcm4use5g7f@corp.supernews.com...
>
>
>
> LOL - Well I hadda ask! What are the specs @ 1 mfd?
Getting your kid sister to pee instead....
--
Sue
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| JohnR66 2006-06-12, 10:21 pm |
| "Palindr?me" <me9@privacy.net> wrote in message
news:128r99q65elig7a@corp.supernews.com...
> PanHandler wrote:
>
> Well, I assumed that you wanted something that would make a significant
> difference.
>
> 4 channels at 350W is 1400W, well over 100A at 12v. Your power supply is
> only rated at 35A surge, so isn't going to cope with anything like full
> output without sagging - even driving just one channel, come to that. So,
> if you are trying to improve the transient handling situation by adding a
> capacitor, it has to be a really big one....You still won't be able to
> drive your amplifiers to anything even remotely approaching full load, but
> will be able to get a lot more dynamic range.
>
> --
> Sue
>
Its a Pyramid brand amp. Don't forget to drop the zero from the power rating
: )
| |
|
| PanHandler wrote:
> I'm using a Pyramid 35 Amp, 12-15 Volt power supply for my 'portable' sound
> system. See here: http://flickr.com/photos/43996336@N00/page4/ , and it's
> been recommended that I install an electrolytic across the supply output.
> The 4 channel, 12Volt amplifier is 'rated' at 350 Watts/channel into 2 Ohms.
> I don't question the recommendation, but would like to be certain of the cap
> values.
> TIA
> Joe Arnold
>
> - - - - - - - - - - - - - - - - - - -
> Easy's getting harder everyday
>
>
If the numbers are accurate, then all the capacitors
in the world won't solve the problem that the numbers
say exists:
Power output = 4*350 = 1400 watts.
Power input = 12*35 = 420 watts.
Real world, unless your eardrums are made out of
concrete, you're not listening to 1400 watts.
How much input power you're using is anybody's
guess, at this point. Whether a cap of any size
would be beneficial is therefore unknown.
Ed
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| PanHandler 2006-06-13, 11:21 am |
|
"ehsjr" <ehsjr@bellatlantic.net> wrote in message
news:gHrjg.12977$Bj6.6496@trnddc08...
> If the numbers are accurate, then all the capacitors
> in the world won't solve the problem that the numbers
> say exists:
> Power output = 4*350 = 1400 watts.
> Power input = 12*35 = 420 watts.
>
> Real world, unless your eardrums are made out of
> concrete, you're not listening to 1400 watts.
> How much input power you're using is anybody's
> guess, at this point. Whether a cap of any size
> would be beneficial is therefore unknown.
Thanks for the note Ed. I understand the math and reasoning, but on Saturday
night, I took the system to a party and it got its first real workout. I
couldn't give it a good hard 'push' here in my small 10' X 17' X 7' room,
but the hall on Saturday was 36 X 75 X 12 feet, with about 80 people
attending. My calibrated SPL meter gave me an A weighted reading of 107 db
on the dance floor, 30 feet from the speakers. The bass was as low, clean
and loud as I wanted, and the rest of the range was superb. I got
complements all night on the sound. All in all, I was quite satisfied,
which, after all, is the bottom line! Here's the layout:
http://flickr.com/photos/43996336@N00/?saved=1 The subs are to the right of
the console.
Joe
| |
| TimPerry 2006-06-13, 12:21 pm |
|
"PanHandler" <panhandler@emptyhat.net> wrote in message
news:i8zjg.12584$gv2.542@bignews3.bellsouth.net...
>
> "ehsjr" <ehsjr@bellatlantic.net> wrote in message
> news:gHrjg.12977$Bj6.6496@trnddc08...
>
> Thanks for the note Ed. I understand the math and reasoning, but on
Saturday
> night, I took the system to a party and it got its first real workout. I
> couldn't give it a good hard 'push' here in my small 10' X 17' X 7' room,
> but the hall on Saturday was 36 X 75 X 12 feet, with about 80 people
> attending. My calibrated SPL meter gave me an A weighted reading of 107 db
> on the dance floor, 30 feet from the speakers. The bass was as low, clean
> and loud as I wanted, and the rest of the range was superb. I got
> complements all night on the sound. All in all, I was quite satisfied,
> which, after all, is the bottom line! Here's the layout:
> http://flickr.com/photos/43996336@N00/?saved=1 The subs are to the right
of
> the console.
> Joe
>
Joe, if you keep doing this sooner or later (probably sooner) you car amp is
going to blow. you might as well get a real amp designed to do what you are
asking it to do.
check out the Behringer EP2500.
"A" weighted measurements of music don't mean a whole lot. "C" weighting
would be more relevant.
| |
| PanHandler 2006-06-13, 12:21 pm |
|
"TimPerry" <timperry@noaspammadlephia.net> wrote in message
news:RIidnbso98S7VxPZnZ2dnUVZ_qednZ2d@adelphia.com...
> Joe, if you keep doing this sooner or later (probably sooner) you car amp
> is
> going to blow. you might as well get a real amp designed to do what you
> are
> asking it to do.
> check out the Behringer EP2500.
> "A" weighted measurements of music don't mean a whole lot. "C" weighting
> would be more relevant.
Hi Tim. Meant to type 'C' weighted. Just looked at the Behringer and the
specs are great. So far, everything (lumber included), but the light chase,
strobe, mirror ball & spot has set me back less than $550, the amp being
under $150. I wanted the option of running off the car batteries (2). I
think I'll look into getting the Behringer, or similar for indoors. I like
the 'sound' of dependability. This whole thing is a work in progress, with
almost daily changes and mods. It's been a blast.
Joe
| |
| Peter Pan 2006-06-14, 12:21 am |
| How true are the rated watts in the new audio equipment. I remember
that some older equipment was rated 100 W and was enough to reach
dangerous levels, not to mention giving you an hernia. This seems worse
in auto and consumer audio.
Could it be that maybe they are rating the maximum instantaneous power
under ideal conditions. Have seem some auto stereos rated 200 W and the
size don't seem to match.
In article <128r99q65elig7a@corp.supernews.com>, Palindr’òªme
<me9@privacy.net> wrote:
> PanHandler wrote:
>
> Well, I assumed that you wanted something that would make a significant
> difference.
>
> 4 channels at 350W is 1400W, well over 100A at 12v. Your power supply is
> only rated at 35A surge, so isn't going to cope with anything like full
> output without sagging - even driving just one channel, come to that.
> So, if you are trying to improve the transient handling situation by
> adding a capacitor, it has to be a really big one....You still won't be
> able to drive your amplifiers to anything even remotely approaching full
> load, but will be able to get a lot more dynamic range.
| |
| TimPerry 2006-06-14, 1:21 am |
|
"PanHandler" <panhandler@emptyhat.net> wrote in message
news:VGAjg.12589$gv2.7978@bignews3.bellsouth.net...
>
> "TimPerry" <timperry@noaspammadlephia.net> wrote in message
> news:RIidnbso98S7VxPZnZ2dnUVZ_qednZ2d@adelphia.com...
amp[color=darkred]
>
> Hi Tim. Meant to type 'C' weighted. Just looked at the Behringer and the
> specs are great. So far, everything (lumber included), but the light
chase,
> strobe, mirror ball & spot has set me back less than $550, the amp being
> under $150. I wanted the option of running off the car batteries (2). I
> think I'll look into getting the Behringer, or similar for indoors. I like
> the 'sound' of dependability. This whole thing is a work in progress, with
> almost daily changes and mods. It's been a blast.
> Joe
>
you might want to lurk a bit on alt.audio.pro.live-sound and/or read some
relevant archives.
just filter out the "mud" and "pick the cherries" if you get what i mean.
i have had pretty good luck on e-bay with used amps. mostly QSC RMX series
and Yorkville Audiopro.
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