There is a very small (size of a cell phone?) audio amp on Ebay for
$20. It's 20W RMS per channel. Looks like it would be a great size
for mounting under the dash and wiring to my front speakers.

What do you guys think? I know it wouldn't sound as good as a high
end amp, but my question is would it sound better than my head unit?
(I have a JVC KD-SX990, which claims to have 19W RMS per channel).
Here is a link to the little amp:
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=3077781544

Thanks,
-Ryan

On 18 Feb 2004 06:25:03 -0800, (Ryan) wrote:

There is a very small (size of a cell phone?) audio amp on Ebay for
$20. It's 20W RMS per channel. Looks like it would be a great size
for mounting under the dash and wiring to my front speakers.

What do you guys think? I know it wouldn't sound as good as a high
end amp, but my question is would it sound better than my head unit?
(I have a JVC KD-SX990, which claims to have 19W RMS per channel).
Here is a link to the little amp:
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=3077781544

Thanks,
-Ryan


from my experibce, HU are a much better source for power then most
dinky amps. Unless you get a REAL nice amp.

from my experibce, HU are a much better source for power then most
dinky amps. Unless you get a REAL nice amp.

Why would this be true? A "HU amp" tends to be nothing more than an IC.

Hard to say... It may be a very similar circuit (in terms of performance)
to the HU amp in your JVC.

Ask the seller what the fuse value is and try and calculate a rough estimate
RMS wattage...

Wrms = Volts x Amps x amp efficiency
Whe
Volts = voltage reading across the amps +/- power leads
Amps = Fuse rating
amp efficiency ~ .8

IMHO its probably about a 10-12 Wrms amp from 20-20K

Garrett

"Ryan" wrote in message
om...
There is a very small (size of a cell phone?) audio amp on Ebay for
$20. It's 20W RMS per channel. Looks like it would be a great size
for mounting under the dash and wiring to my front speakers.

What do you guys think? I know it wouldn't sound as good as a high
end amp, but my question is would it sound better than my head unit?
(I have a JVC KD-SX990, which claims to have 19W RMS per channel).
Here is a link to the little amp:
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=3077781544

Thanks,
-Ryan

Hard to say... It may be a very similar circuit (in terms of performance)
to the HU amp in your JVC.

Ask the seller what the fuse value is and try and calculate a rough
estimate
RMS wattage...

Wrms = Volts x Amps x amp efficiency
Whe
Volts = voltage reading across the amps +/- power leads
Amps = Fuse rating
amp efficiency ~ .8

IMHO its probably about a 10-12 Wrms amp from 20-20K

The power will essentially be limited by the rail voltage. So I sincerely
doubt it will be less power than a head unit. In fact, it could be more if
they step up the rails from 12v.

Ryan wrote:
There is a very small (size of a cell phone?) audio amp on Ebay for
$20. It's 20W RMS per channel. Looks like it would be a great size
for mounting under the dash and wiring to my front speakers.

What do you guys think? I know it wouldn't sound as good as a high
end amp, but my question is would it sound better than my head unit?
(I have a JVC KD-SX990, which claims to have 19W RMS per channel).
Here is a link to the little amp:
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=3077781544


That depends - the only barrier to making amps small is heat. Battling
heat requries large heat sinks, and large componants in the power
supply. While its reasonable to assume this amp has a proper DC to DC
power supply and can produce 40 watts RMS, its also reasonable to assume
its going to produce a lot of heat. I'm not sure I'd stuff this up under
the dash where it could damage wiring when it overheats.

Jensen had a tiny amp along time ago, and it was awesome. It was great
for people who bought decks that didn't have their own amps (like my old
Eclipse 5302). They were great for biamping tweeters. Although you
weren't supposed to, you could bridge the Jensen and drive a small bass
tube. I had one guy who bought four of these to power his speakers then
came back and bought two more to drive his DVC JBL sub. We wound up
taking two of these that had burned out to make encaps, and lined all
the amps up into one big long one (kinda like the Memphis Belle amp,
only it was Jensen blue). That was fun, and it sounded good.

What I can't tell you about is the brand. At $0.50 per watt, its only
ten cents cheaper than a quality amp like DEI which offers a
continuously variable crossover, and more features this amp doesn't. So,
it's a matter of equity. I'd buy one to play with, but I wouldn't rely
on it for my system. Always remember that you get what you pay for, and
you rarely get more.


--
thelizman

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
teamROCS Car Audio News http://www.teamrocs.com/news/
"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.

MZ wrote:
from my experibce, HU are a much better source for power then most
dinky amps. Unless you get a REAL nice amp.

Why would this be true? A "HU amp" tends to be nothing more than an IC.

He did qualify that by saying "in [his] experience". IME, dinky amps are
better. They can play slightly cleaner, and they have more actual power
because they have a DC to DC power supply. Those IC amps cannot reliably
and cleanly produce more than about 10 watts RMS. Those 100x4 wattage
claims are usually peak values at very high levels of THD and clip.

--
thelizman

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
teamROCS Car Audio News http://www.teamrocs.com/news/
"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.

sanitarium wrote:
Hard to say... It may be a very similar circuit (in terms of performance)
to the HU amp in your JVC.

Ask the seller what the fuse value is and try and calculate a rough estimate
RMS wattage...

Wrms = Volts x Amps x amp efficiency
Whe
Volts = voltage reading across the amps +/- power leads
Amps = Fuse rating


amp efficiency ~ .8

Brrat! Thats a sweeping generalization. IME, smaller amps tend to
actually be less efficient. If it is truly just an IC amp like what is
in the headunit (no switching power supply), then it could only be 25%
efficient.

Hell, for $20, I say we buy one and run the tests on it. Hell, this
might be one of those rare products which exceed expectations.

Oh, and by "we", I mean "you", because I'm broke.

--
thelizman

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
teamROCS Car Audio News http://www.teamrocs.com/news/
"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.

Why would this be true? A "HU amp" tends to be nothing more than an IC.

He did qualify that by saying "in [his] experience". IME, dinky amps are
better. They can play slightly cleaner, and they have more actual power
because they have a DC to DC power supply. Those IC amps cannot reliably
and cleanly produce more than about 10 watts RMS. Those 100x4 wattage
claims are usually peak values at very high levels of THD and clip.

And a heaping of bull**** to boot. The one possible exception to your
comment would be some of these Alpine units that do use a DC-DC, and have
actually tested out somewhere in the 20-25wrms per channel range. The
obvious problem, however, is that they get hot as hell and draw a lot of
current (even more than the old "oops" Eclipse decks). I don't know about
you, but I'd be very wary of the life of a head unit that gets burning-hot,
especially in one of those cars that has very little room behind the dash
for ventilation.

On Wed, 18 Feb 2004 11:12:29 -0500, "MZ"
wrote:

from my experibce, HU are a much better source for power then most
dinky amps. Unless you get a REAL nice amp.

Why would this be true? A "HU amp" tends to be nothing more than an IC.



i bet that amp he is looking at puts out less then a good HU

from my experibce, HU are a much better source for power then most
dinky amps. Unless you get a REAL nice amp.

Why would this be true? A "HU amp" tends to be nothing more than an IC.



i bet that amp he is looking at puts out less then a good HU

And I bet it doesn't. I win.

interesting... didn't know that. Is that why many head unit amps seem
to run so much hotter than outboard amps?

Garrett

thelizman wrote:

sanitarium wrote:

Hard to say... It may be a very similar circuit (in terms of
performance)
to the HU amp in your JVC.

Ask the seller what the fuse value is and try and calculate a rough
estimate
RMS wattage...

Wrms = Volts x Amps x amp efficiency
Whe
Volts = voltage reading across the amps +/- power leads
Amps = Fuse rating



amp efficiency ~ .8


Brrat! Thats a sweeping generalization. IME, smaller amps tend to
actually be less efficient. If it is truly just an IC amp like what is
in the headunit (no switching power supply), then it could only be 25%
efficient.

Hell, for $20, I say we buy one and run the tests on it. Hell, this
might be one of those rare products which exceed expectations.

Oh, and by "we", I mean "you", because I'm broke.

"sanitarium" wrote in message news:1077125195.461481@sj-nntpcache-5...
Hard to say... It may be a very similar circuit (in terms of performance)
to the HU amp in your JVC.

Ask the seller what the fuse value is and try and calculate a rough estimate
RMS wattage...

Wrms = Volts x Amps x amp efficiency
Whe
Volts = voltage reading across the amps +/- power leads
Amps = Fuse rating
amp efficiency ~ .8

IMHO its probably about a 10-12 Wrms amp from 20-20K

Garrett

Well I've emailed the seller and asked him the fuse size. Also if he
knows if this is a mosfet design (will this tell us something?), and
if it has a DC-to-DC power supply (maybe this is the same as being of
a mosfet design??). I also asked him if he could take a picture of
the inside and email it to me. This would answer our questions, I
think.

I have a feeling that because of the size, price, and brand that it is
probably a worthless IC amp. Oh and I was wrong in my first post
about the wattage, I said it was 20w RMS x 2, I see now that it says
it's 25w RMS x 2.

I think I might email the manufacturer and ask them about it, too. If
I come up with anything I will report back.

Thanks for all the comments.
-Ryan

sanitarium wrote:
interesting... didn't know that. Is that why many head unit amps seem
to run so much hotter than outboard amps?

Basically, yeah. Most (not all) headunits don't have a DC to DC power
supply, and they voltage steppers to raise the output of the amplifier.
These are very inefficient, hence the head.

--
thelizman

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
teamROCS Car Audio News http://www.teamrocs.com/news/
"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.

I'm looking for a small in size and amps (5-10 watts mono) to amplify my
audio out of my radar detector on my motorcycle if anyone knows of one
please post details.
Joe Foe from Buffalo :-)

Joe Foe wrote:
I'm looking for a small in size and amps (5-10 watts mono) to amplify my
audio out of my radar detector on my motorcycle if anyone knows of one
please post details.

Wow, that would likely be overkill. 5 or 10 watts at a single tone might
be more than you want. Irregardless, Rat Shack has you covered.

http://www.radioshack.com/product.as...%5Fid=277-1008

Personally, I just mount the detector in my FOV so when it goes off I
see it. Actually, that's not true. I don't even use a radar detector
anymore. They don't work as well as paying attention.


--
thelizman

teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/
teamROCS Car Audio News http://www.teamrocs.com/news/
"It's about the music, stupid"

This post is Copyright (C) 2004. Reproduction of its content anywhere
other than usenet without the express written permission of the author
is forbidden.

This is what I have all ready but want a better/smaller amp. (sorry if I'm
hijacking the post)
A V1 Radar detector with water resistant extra load speaker (no wires to
helmet)
http://www.valentine1.com/
I also have the external speaker add on for the V1/ external speaker
attachment made by V1.
https://store.valentine1.com/store/products/20200h.jpg
That has a speaker jack that I have plugged in to a Mini Piezo Siren
#330-068
http://www.partsexpress.com/pe/pshow...Number=330-068
Which can be purchased at any Radio Shack or most any place that installs
car alarms. The Piezo does need more power to be herd at higher speeds
(100+MPH) though. So I have a small power amp made by Car-Fi #
(EQP)PA-EPR100
http://www.surplussales.com/micropho...roaudio-6.html
to bring more power to the Piezo speaker (around 10 Watts).
I also have the V1 remote display that I mount on the upper inside lip of
the wind shield.
https://store.valentine1.com/store/products/20110ha.jpg

Also had one of these and getting the a new version in spring.
http://www.legalspeeding.com/product.htm

--
Joe Foe from Buffalo :-)

Yeah post links to a pic of the insides if he does reply... Id be curious.
Most of the mobile authority amps (but not MA audio) Ive opened up were just
a big heatsink with a small PCBA and long lead wires running around to the
power/ground. Kind of like this...

http://arawndark.netfirms.com/AMP450/index.htm


"Ryan" wrote in message
om...
"sanitarium" wrote in message
news:1077125195.461481@sj-nntpcache-5...
Hard to say... It may be a very similar circuit (in terms of
performance)
to the HU amp in your JVC.

Ask the seller what the fuse value is and try and calculate a rough
estimate
RMS wattage...

Wrms = Volts x Amps x amp efficiency
Whe
Volts = voltage reading across the amps +/- power leads
Amps = Fuse rating
amp efficiency ~ .8

IMHO its probably about a 10-12 Wrms amp from 20-20K

Garrett

Well I've emailed the seller and asked him the fuse size. Also if he
knows if this is a mosfet design (will this tell us something?), and
if it has a DC-to-DC power supply (maybe this is the same as being of
a mosfet design??). I also asked him if he could take a picture of
the inside and email it to me. This would answer our questions, I
think.

I have a feeling that because of the size, price, and brand that it is
probably a worthless IC amp. Oh and I was wrong in my first post
about the wattage, I said it was 20w RMS x 2, I see now that it says
it's 25w RMS x 2.

I think I might email the manufacturer and ask them about it, too. If
I come up with anything I will report back.

Thanks for all the comments.
-Ryan