# Pioneer SX-950 VS Adcom GFA-545 II



## rentonhighlands

What make a amp sound better then another? I know the sound to one person may sound different the some one else. To me the Pioneer SX-950 sounds warmer and makes a fuller sound. What causes this?


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## jackfish

The Pioneer SX-950 is a receiver, containing individual preamp, power amp and tuner sections in one box, while the Adcom GFA-545 II is a power amp. Much of the difference could be the preamp used with the Adcom. What preamp did you use with the Adcom for your comparison? Could be that the preamp and power amp didn't work well together.


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## rentonhighlands

I am using my computer (mobo sound card) as the pre-amp with my adcom. With the SX-950 I only used it and sent the audio from the computer. 
The comparison was using the same song. 
There is a huge difference. The SX-950 sounds (imo) a lot cleaner and clear.


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## rentonhighlands

jackfish: Got a hook up question for you. Now that I have a powered sub I want to use my SX-950 to run my left and right speakers instead of my adcom power amp. What is the best way to hook it up? 
Right now I am using a spliter from mobo 1 rca to the power amp and 1 rca to the powered sub. 
I guess my question would it be best to take out the power amp and add the sx-950. Or run audio to the sx-950 and hook the sub to the sx-950 somehow.


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## jackfish

Hook up the loudspeakers to the A speaker terminals. The subwoofer could be implemented with appropriate adapters from the preamp out/power in. Two 2-male to 1 female RCA adapters like this http://www.newegg.com/Product/Product.aspx?Item=N82E16882719287 and a regular stereo RCA cable. The speakers will run full range but set the sub low pass filter to the -3dB low frequency point of the speakers.


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## rentonhighlands

This is the plate amp I have. 
Dayton SA240-B 240W Subwoofer Amplifier with Boost
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-805

What do you mean by this statement: The speakers will run full range but set the sub low pass filter to the -3dB low frequency point of the speakers. I understand that the loudspeakers will run full range but I do not understand the "set the sub low pass filter to the -3db low freqency point of the speakers. Could you explain this a bit more. 

If my amp does not have this setting then does this mean that the sub is running at full range. I do not want the sub to run at full range.


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## rentonhighlands

Jackfish: 
I found this tread. Is this what you are explaining? 
http://www.audiokarma.org/forums/showthread.php?t=281993


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## jackfish

If you run your loudspeakers from the 'A' speaker terminals of the SX-950, the speakers will be getting output from the full frequency range the SX-950 is capable of providing. That's OK because your loudspeakers have an inherent low frequency rolloff point which can be considered the -3dB point. So, if your speakers have a rated frequency response of 40Hz-20kHz +/-3dB their low frequency rolloff is around 40 Hz. Taking a RCA adapter linked to previously and plugging the male leads into the preamp out and power in jacks of the right channel and another such RCA adapter likewise into the left channel leaves you a right and left channel output you can then use a stereo RCA cable to connect to the right and left 'Low Level' input RCA jacks on your subwoofer amp. The sub can be fed frequencies below the low pass filter point delineated by the 'FREQ.' dial on the far right of the amp. In the example speakers above you would set it to the lowest setting, 40 Hz.

You could also set it up a couple other ways. 

One way using the high level inputs of the sub in which you would run SX-950 'A' speaker terminal wires to your loudspeakers the same as the first example and then run speaker wires from the SX-950 'B' terminals to the high level 'FROM AMPLIFIER" terminals on the subwoofer and set the 'FREQ.' low pass filter as before. 

A second way you would run the SX-950 'A' speaker terminal wires to the high level 'FROM AMPLIFIER" terminals on the subwoofer and then run a second set of speaker wires from the high level 'TO SPEAKERS' terminals on the subwoofer to your loudspeakers. However, this will employ at high pass filter sending frequencies above 125 Hz to the loudspeakers in which case you would likely want to set the 'FREQ.' low pass filter on the sub to around 125 Hz as well.

Hope that is as clear as mud. :yikes:


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## jackfish

Oh yeah, what kind of loudspeakers will you be using?


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## rentonhighlands

The loud speakers I am using are ones from parts express. They were designed by a friend of mine. He designed some custom crossovers that are in each of the boxes. I would have to look at my paper work to find out what the roll off point is. The boxes are the Dayton TWC-0.75BK 0.75 ft³ 2-Way Curved Cabinet Gloss with 1 dayton 7" driver and 1 dayton 1" tweeter in each. They sound very nice.


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## rentonhighlands

What about hooking it up this way. Would this way work? I have a Y stereo splitter from my mobo plugged into the out jack. Take one and run one set of RCA to the SX-950. Take the other plug on the Y splitter and run right and left to the sub. Then take speaker wire from the SX-950 A and run them to the loud speakers.


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## jackfish

Sure, why not? But I assume the soundcard on your motherboard uses a 1/8" stereo plug for output. Hence, you would need an 1/8" stereo male to two RCA female adapter just to get a right and left channel for a stereo RCA cable to run to the SX-950. If you want to add the subwoofer you need 2 one male RCA to two female RCA adapters so you have a pair of right and left channel outputs, e.g. a right and left output for the SX-950 and a right and left output for the subwoofer. A pair of regular stereo RCA cables would complete the hookup.

One of these: 1/8" stereo male to two RCA female adapter
And two of these: One male RCA to two female RCA adapters


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## rentonhighlands

Yes the MOBO uses 1/8" out. What I have right now is 1/8" out to a female Y RCA cable. I then have 1 1/8" rca plugged into one side of the Y running left and right to the power amp. Then on the other side of the Y I have 1/8" RCA plugged in running right and left to the sub. What I was thinking is take out the power amp and plug in the SX-950. Would this work?


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## rentonhighlands

I think I follow what you are stating. I just want to make sure I am getting the signal path correct to produce the best sound and to make sure I am not making the sub play full range. But what I have right now is two cables they are 1/8" to male right and left RCA. And I have 1 Belkin 3.5mm Stereo Y Adapter 6" Cable 1 Plug to 2 Jacks http://www.parts-express.com/pe/showdetl.cfm?Partnumber=249-146

Sorry in the previous post I made a mistake on what cables I have. But I am going to take one side of the Y adapter to the SX-950 and the other side to the sub.


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## jackfish

That will do it. Let us know how it works.


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