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Old 27th June 2012, 07:35 AM   #1
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Default Looking for the right IC for an amp project.

I'm building a small (very small) speaker system for my motorcycle. I have two small 1.5" fronts that mount to the bars plus a sub under the seat. Yes a sub. The fronts will be crossed over fairly high to avoid distortion and the "sub" will also be crossed over high to fill in where the fronts can't.

One IC I've been playing with is a TDA8560 which is very easy to work with and has decent power for only a single 12v supply. This is fine for the fronts. Does anyone know of a bridgeable version of that IC or maybe another 30-40w IC that's as simple to wire as the TDA8560? It would be ideal to use the same part# IC because 20w/ch to the fronts blends well with 40w to the sub but it needs to be bridgable in that case.

On another note, I'm sitting here listening to music through some goofy 2" speakers pulled from a Sony TV and a 5w/ch IC amp from some Logitech speakers. I'm a bit taken away by how good this sounds for what it is. Anyway...
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Old 27th June 2012, 07:50 AM   #2
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The TDA8560 is a bridged amplifier; look at the datasheet. If you want twice the power to the sub you either need a 2-Ohm sub, a dual VC sub, or an IC running at twice the voltage.
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Old 27th June 2012, 08:29 AM   #3
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"bridgeable" as in a stereo IC capable of single channel operation. It's internal topology is not important to me. I can use one IC for the two fronts and another bridged to drive the sub. The sub is 4" and was hard enough to find a decent one let alone one with dual voice coils. I found a DVC 6" but it won't fit.
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Old 27th June 2012, 10:05 AM   #4
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Quote:
Originally Posted by lazzer408 View Post
"bridgeable" as in a stereo IC capable of single channel operation.
That's called "mono", not "bridgeable". Misusing terms won't help you get the answers you're looking for.

I think you need to understand what a bridged amp is and how supply voltage is related to power output before you can understand what options best suit your needs.
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Old 27th June 2012, 10:31 AM   #5
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Another important issue( matter ) is the noise floor (?!? )
A motorcycle in the traffic is different to a room which might be well isolated from external noises . But maybe you intended to listen in a quiet environment ,like parks , woods
In the '80s the good ol' TDA 2009 filled the duties for 2.1 setups in mobile applications , using two subs , so 4 X tda 2009 in total , with a passive HP filter
( 330nF+3k3Ω;100nF+18 KΩ ) for satellites and a mixer + 3rd order lowpass
using a dual IC for the subs .
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Old 27th June 2012, 06:24 PM   #6
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Quote:
Originally Posted by theAnonymous1 View Post
That's called "mono", not "bridgeable". Misusing terms won't help you get the answers you're looking for.
So what is it called when I use a stereo amplifier wired to use both channels to drive a single load?

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Originally Posted by theAnonymous1 View Post
I think you need to understand what a bridged amp is and how supply voltage is related to power output before you can understand what options best suit your needs.
I understand the supply and load are limiting factors. If I have to I'll build a smps to suit my needs or get a cheap 12 to 24 dc-dc.

If I knew everything I wouldn't need to ask.

Quote:
Originally Posted by picowallspeaker View Post
Another important issue( matter ) is the noise floor (?!? )
A motorcycle in the traffic is different to a room which might be well isolated from external noises . But maybe you intended to listen in a quiet environment ,like parks , woods
In the '80s the good ol' TDA 2009 filled the duties for 2.1 setups in mobile applications , using two subs , so 4 X tda 2009 in total , with a passive HP filter
( 330nF+3k3Ω;100nF+18 KΩ ) for satellites and a mixer + 3rd order lowpass
using a dual IC for the subs .
The setup I tried for the bike has a TA8210 on the fronts and it was plenty loud for use on a motorcycle. It doesn't take much when the speakers are 18" from my ears. The sub on the other hand will be hard to hear when riding. It's only 4" and I haven't set any design in stone. I have room under the rear fender for two 4" in a sealed tube but there's no way to mount the sub in direct line to my ears. Once I find an IC that will work, I'll try a few positions and see what works best.

I'm not against using a mono IC for the sub. It has to have a minimum of external components. I'm limited on space for the amplifier.

Last edited by lazzer408; 27th June 2012 at 06:41 PM.
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Old 27th June 2012, 06:51 PM   #7
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Here's an example of what I'm sort of looking for.

http://www.datasheetcatalog.org/data...TDA8947J_2.pdf This IC can operate in 4ch mode or bridged as 2+1 or 1+1.

-or-

http://www.st.com/internet/com/TECHN...CD00000164.pdf This IC does 45w into 2ohm 10% THD at 14.4v (If I'm reading the DS correctly)

I don't think I'll get much better then that second link. Minimal components and high power.

EDIT - I just realised I can tap the 3-phase power from the alternator before it hits the regulator and make a dual-rail supply very easily from that. This widens my options greatly. There are plenty of high-power IC kits available that run off of dual-rail supplies.

Last edited by lazzer408; 27th June 2012 at 07:21 PM.
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Old 27th June 2012, 07:05 PM   #8
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Quote:
Originally Posted by lazzer408 View Post
So what is it called when I use a stereo amplifier wired to use both channels to drive a single load?
I don't know, are the two channels paralleled mono or bridged mono? An amplifier can be mono and still be single ended. Likewise a stereo amp can have bridged outputs, like your TDA8560. It's not "dual mono", it's a stereo BTL amplifier.

No one's saying you shouldn't ask questions, but don't use incorrect terminology and then get defensive when someone tries to explain the different terms.

And to show you I'm not trying to be a ****, I'll suggest one option for higher power without using a higher supply voltage or a lower impedance load.....

http://www.nxp.com/documents/data_sh...562Q_ST_SD.pdf

Last edited by theAnonymous1; 27th June 2012 at 07:07 PM.
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Old 27th June 2012, 07:16 PM   #9
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Quote:
Originally Posted by lazzer408 View Post
Here's an example of what I'm sort of looking for.

http://www.datasheetcatalog.org/data...TDA8947J_2.pdf

This IC can operate in 4ch mode or bridged as 2+1 or 1+1.
Operating that from a 12V suppy in 2.1 mode will give you about 1/4 the power to the highs as you are getting with the TDA8560 since the outputs would be single ended. The BTL sub channel will only give half the power as the TDA8560 since the IC is only specced to drive >8-Ohm loads bridged.
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Old 27th June 2012, 08:34 PM   #10
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Quote:
Originally Posted by theAnonymous1 View Post
I don't know, are the two channels paralleled mono or bridged mono? An amplifier can be mono and still be single ended. Likewise a stereo amp can have bridged outputs, like your TDA8560. It's not "dual mono", it's a stereo BTL amplifier.
What I know about bridging comes from my car audio days. When a 2 channel "amplifier" drives a single channel, it's bridged. That's all I know. So are these 2ch BTL ICs actually 4ch (of opamps) that are internally bridged into 2ch worth of output? I've found ICs that are 2ch that can be bridged into one. What's different about those?

Anyway we look at it. I'm not any closer to a solution. I need to find a low parts count, 12v, high power, stereo IC that can be bridged to drive a single channel.
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