Uncripple plate amp

mashaffer · 25th July 2007, 01:25 AM

I am not sure whether it makes more sense to post this here or in the SS section so feel free to move it is more appropriate there. I read through several pages of hits and didn't find what I needed.

I have an AR S108PS 8" "subwoofer" from which I would like to use the 120W plate amp with a 12" system I am putting together. I pulled the speaker wires out to play with it on the new driver and it worked pretty well except that they seem to have put a HP filter at about 37Hz so I am not getting the full potential of the driver. No doubt they did this to protect the little driver.

I have searched the net for a schematic with no luck. So my question is how feasible is it to attempt to figure out their implementation of the filter and disable it? Do most of these amps use similar layout that would help identify the offending circuitry? Does anyone have experience with this actual amp that could help get me started?

I have not pulled the amp to look yet but will do so sometime this week probably.

Any suggestions appreciated as I would really rather use this amp if possible rather than build my own chip amp.

mike

planet10 · 25th July 2007, 05:34 AM

Can you post some pictures?

dave

mashaffer · 25th July 2007, 11:15 PM

You will be wanting pictures of the circuit boards I take it. Will try to get that done this weekend and post pics early in the week. USB output on the digital camera no longer works to I will have to take pics and then get a CD made so will take some time.

mike

AndrewT · 28th July 2007, 09:50 AM

Hi,
the amp may simply have a high pass filter. Many do this.

But it could be one of the better designs that is a 5th or 6th order alignment that uses a variety of different Qs and filters to extend the bass response and get more volume without overloading the driver.

You must identify what you have.

If you copy a Linkwitz alignment, I think you get the same as a 5th order alignment. You can then design the alignment to exactly suit your new driver.

mashaffer · 29th July 2007, 12:48 AM

I took some pictures today and will get a CD made in the next couple of days but I thought that I would go ahead and describe what I saw.

The circuit board has the following printed on it.

PLAIN REV 5.1

AMI COPYRIGHT 1999

There is a large flat can about like a stack of 30 business cards mounted on its long edge. There is a label stuck on it that says

S53AMI

On the side of the can a number is stamped that looks like

012800

The can has 14 sets of contacts soldered to the board. It appears to be a PC board inside of the can.

Directly below the can are two fairly large (the largest on the board) electrolytic caps of 3300uF 50V.

On the right side of the board where the main power xformer secondary connects to the board there is a small toroid, a bridge rectifier and a couple of green (mylar?) caps labeled

1040 100V

I assume this is the SMPS.

The speaker output has a small cap that looks like a small signal diode (labeled C24) across the two leads. There is a small electrolytic mounted between the output leads also but it is not clear whether it is connected to the speaker lugs or not.

On the lower left of the board is a 14 pin DIP labeled.

LA6324N
9S7

It appears that there is a small CT transformer connected to the negative leg of the speaker output. It appears that one end of what I assume is the secondary is connected there. it looks like the "primary" of this transformer may be connected to a small inductor labeled "L2" on the board. I wonder if this could be part of of filter network like Andrew mentioned.

I can't identify an output device however it/they my be encased in the plastic compartment (sealed with Moose Snot) on the edge of the card where the external connectors and controls are housed.

mike

mashaffer · 30th July 2007, 10:42 PM

Here are the pics.

mashaffer · 30th July 2007, 10:44 PM

Another view.

mashaffer · 30th July 2007, 10:51 PM

And the plate side.

Unfortunately I didn't think to take a picture of the back side of the PCB.

mike

mashaffer · 3rd August 2007, 01:24 AM

Planet, are those pictures of any help at all?

mike

planet10 · 3rd August 2007, 05:32 AM

I'm just surfacing from the WE diyFEST.

Anything of interest will be around the quad opamp. We'll need to the circuit.

dave

25th July 2007, 01:25 AM	#1
mashaffer diyAudio Member Join Date: Jun 2004 Location: Indiana	Uncripple plate amp I am not sure whether it makes more sense to post this here or in the SS section so feel free to move it is more appropriate there. I read through several pages of hits and didn't find what I needed. I have an AR S108PS 8" "subwoofer" from which I would like to use the 120W plate amp with a 12" system I am putting together. I pulled the speaker wires out to play with it on the new driver and it worked pretty well except that they seem to have put a HP filter at about 37Hz so I am not getting the full potential of the driver. No doubt they did this to protect the little driver. I have searched the net for a schematic with no luck. So my question is how feasible is it to attempt to figure out their implementation of the filter and disable it? Do most of these amps use similar layout that would help identify the offending circuitry? Does anyone have experience with this actual amp that could help get me started? I have not pulled the amp to look yet but will do so sometime this week probably. Any suggestions appreciated as I would really rather use this amp if possible rather than build my own chip amp. mike

25th July 2007, 05:34 AM	#2
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	Can you post some pictures? dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

28th July 2007, 09:50 AM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, the amp may simply have a high pass filter. Many do this. But it could be one of the better designs that is a 5th or 6th order alignment that uses a variety of different Qs and filters to extend the bass response and get more volume without overloading the driver. You must identify what you have. If you copy a Linkwitz alignment, I think you get the same as a 5th order alignment. You can then design the alignment to exactly suit your new driver. __________________ regards Andrew T.

3rd August 2007, 05:32 AM	#10
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	I'm just surfacing from the WE diyFEST. Anything of interest will be around the quad opamp. We'll need to the circuit. dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

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25th July 2007, 11:15 PM	#3
mashaffer diyAudio Member Join Date: Jun 2004 Location: Indiana	You will be wanting pictures of the circuit boards I take it. Will try to get that done this weekend and post pics early in the week. USB output on the digital camera no longer works to I will have to take pics and then get a CD made so will take some time. mike

29th July 2007, 12:48 AM	#5
mashaffer diyAudio Member Join Date: Jun 2004 Location: Indiana	I took some pictures today and will get a CD made in the next couple of days but I thought that I would go ahead and describe what I saw. The circuit board has the following printed on it. PLAIN REV 5.1 AMI COPYRIGHT 1999 There is a large flat can about like a stack of 30 business cards mounted on its long edge. There is a label stuck on it that says S53AMI On the side of the can a number is stamped that looks like 012800 The can has 14 sets of contacts soldered to the board. It appears to be a PC board inside of the can. Directly below the can are two fairly large (the largest on the board) electrolytic caps of 3300uF 50V. On the right side of the board where the main power xformer secondary connects to the board there is a small toroid, a bridge rectifier and a couple of green (mylar?) caps labeled 1040 100V I assume this is the SMPS. The speaker output has a small cap that looks like a small signal diode (labeled C24) across the two leads. There is a small electrolytic mounted between the output leads also but it is not clear whether it is connected to the speaker lugs or not. On the lower left of the board is a 14 pin DIP labeled. LA6324N 9S7 It appears that there is a small CT transformer connected to the negative leg of the speaker output. It appears that one end of what I assume is the secondary is connected there. it looks like the "primary" of this transformer may be connected to a small inductor labeled "L2" on the board. I wonder if this could be part of of filter network like Andrew mentioned. I can't identify an output device however it/they my be encased in the plastic compartment (sealed with Moose Snot) on the edge of the card where the external connectors and controls are housed. mike

3rd August 2007, 01:24 AM	#9
mashaffer diyAudio Member Join Date: Jun 2004 Location: Indiana	Planet, are those pictures of any help at all? mike

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