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QSC PLX 1202 AMP hooked up - Thanks Dean


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I think that model is around 21 db-a. Anything in that neighborhood would be quiet enough.

I have some old fans I took out of some Digital Equipment Corp. power supplies. They don't build them like THAT anymore. Ball bearing fan assemblies. Very quiet and should last a long time. Most pc fans are sleeve bearings, and they wear out too quickly.

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I have two Alesis RA-100 amps. 100 wpc into 4 ohms. No fans at all. They don't make the model anymore, and you can pick them up on ebay for cheap.

I know there are lots better SS amps, but it is pretty clean. Mine never even get more than warm.

The new QSC amps would be great though, due to the newer PS design.

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If I had the money I would really wanna give these amps a demo:

245-861m.jpg

They have a 200 watt version (shown, $279) and a smaller/cheaper 100 watt version ($219).

Here's the digi-key list of fans:

http://dkc3.digikey.com/PDF/T052/1418-1426.pdf

I couldn't find the panasonic panoflo fans in the listing though...

Btw, what is this dBa rating? Is it basically how loud the fan is per amp? (ie, a 21dba fan is 42dB loud when driven with 2 amps?)

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Here's the digi-key list of fans:

http://dkc3.digikey.com/PDF/T052/1418-1426.pdf

I couldn't find the panasonic panoflo fans in the listing though...

Btw, what is this dBa rating? Is it basically how loud the fan is per amp? (ie, a 21dba fan is 42dB loud when driven with 2 amps?)

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I can't find the fan. The QSC needs a 80mm x 80mm x 25mm 24 volt fan. From what I read, it comes with a panaflo "h" for high flow and needs an "L" for low flow. There are a lot of 12v fans for computers, but not many 24v fans out there. Can a resistor or some kind of easy mod be done to lower the fans level? It is pretty quiet except for when the room is silent.

I took a reading with a rat shak meter. No reading at one foot. When I put the meter right up to the grill I registered in the mid 50's for db.

Any help is appreciated. I just love this amp.

Chris

EDIT:

OK I just go thtis info:

Panaflo FBA08A24L 80 mm 24vdc .09a

Panaflo FBA08A24H 80 mm 24vdc .17a

It seems that the only difference is that the H uses .17a and the l uses 0.09a (1/2 of the H)

I forget the formula. It is v= I/R right (its been a long time since engineering school!)

If that is correct, if I double the resistance, the V is constant so "I" should drop to 1/2 of the amperes. the only problem is that I need to measure the resistance of the fan now.

Is this correct?

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On 7/3/2005 11:14:21 AM tigerwoodKhorns wrote:

EDIT:

OK I just go thtis info:

Panaflo FBA08A24L 80 mm 24vdc .09a

Panaflo FBA08A24H 80 mm 24vdc .17a

It seems that the only difference is that the H uses .17a and the l uses 0.09a (1/2 of the H)

I forget the formula. It is v= I/R right (its been a long time since engineering school!)

If that is correct, if I double the resistance, the V is constant so "I" should drop to 1/2 of the amperes. the only problem is that I need to measure the resistance of the fan now.

Is this correct?

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Well, V=IR... and you have the needed current - 0.17A, as well as the Voltage - 24V

So the resistance of the fan is R = V/I = 24/0.17 = 141ohms

So I would say if you get 3 or 4 100ohm resistors (make sure they are rated 5-10W, not less) and wire them in series, you should be in business.

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DrWho,

I recently fixed one of those ART amps for a friend of mine. It was given to him by another acquaintance. All that was wrong with it was that the fuse holder solder connection was broken. Took all of ten minutes to fix. Those have a very small fan in the back of them, like a 25mm or something. Pretty clean amp, and the fan doesn't make much noise. Not a chip amp, but uses regular transistors.

The dba rating is the noise the fan makes. db A weighting. The noise level comes from the fan blade shape and the speed of rotation, blah, blah... The grill on the fan can also be a cause for noise.

You can take a 24volt fan and connect it to a 12volt supply and slow it down that way. But the 12volts make not give enough torque to have it start 15.gif .

Try this part number in a search at digikey:

P9739-ND

So... you are going to add resistors to slow down the fan. Then you can just use the fan to cool off the resistors.

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Try this part number in a search at digikey:

P9739-ND

So... you are going to add resistors to slow down the fan. Then you can just use the fan to cool off the resistors.

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Marvel,

Thanks. I will order one fo those fans. I could not find it anywhere. Do I need to order a wire "pigtail" to go with it to hook it up?

Thanks,

Chris

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On 7/6/2005 12:40:22 AM tigerwoodKhorns wrote:

Marvel,

Ordered the low noise panaflo fan this morning. Less than $20 delivered. Thanks, I was really having a hard time finding one. My only complaint with the amp was teh fan noise (although it is only audible between tracks).

Chris

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You'll have to let us all know how the new fans work out...I am very interested in the mod as well, but just haven't gotten around to it yet.

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On 7/6/2005 3:12:36 AM DrWho wrote:

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On 7/6/2005 12:40:22 AM tigerwoodKhorns wrote:

Marvel,

Ordered the low noise panaflo fan this morning. Less than $20 delivered. Thanks, I was really having a hard time finding one. My only complaint with the amp was teh fan noise (although it is only audible between tracks).

Chris

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You'll have to let us all know how the new fans work out...I am very interested in the mod as well, but just haven't gotten around to it yet.

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The original amp is actually pretty quiet. My guess is that with the new fan (like 20 something db compared ot in the 50's - I think) will be virtually dead silent. The fan is in the back of the unit, which helps.

Chris

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