SA-9100 clipping on pre outs.

CrispySqrl

New Member
Hello everyone. Thanks to this site and it's awesome people we got the SA-9100 playing. But it is clipping (audible distortion)at 1/4 volume so upon further testing it is clipping coming out of even the pre out rca's I am just starting to read the service manual on the control amplifier board as I am assuming it is the culprit.

If anyone has any incite let me know. I will post any findings either way.

Thanks,
Darrell
 
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what do you mean by clipping ? are you looking at the signal on a scope ?
input could be too high for amp .
what input are you plugging into ?
 
I don't have a scope, I do have a device purpose built for audio that measures 1khz and 40hz and shows clipping when playing those freqs through it. The input device (PC) is not clipping we tried the aux1 aux 2 and tuner inputs just to make sure.
 
The input voltage to the 9100 could be too high from the PC. Look at the input sensitivity specs in the owners manual. Sounds like you are OVERDRIVING the 9100. turn down the Volume or gain on the PC

Manual here
 
The input voltage to the 9100 could be too high from the PC. Look at the input sensitivity specs in the owners manual. Sounds like you are OVERDRIVING the 9100. turn down the Volume or gain on the PC

Manual here
The PC's output is only 120mv at 100% volume and we were only using 50% volume to be sure no clipping was coming from the PC which was happening around 75%.

The owners manual states 150mv on Aux1 so I don't think it is an overdrive issue.
 
Be aware that the power amplifier section only needs 0.500v to achieve maximum wattage out, while the output of the preamp is 2.000v

In normal mode there is a 4:1 voltage divider between the two.

If you are running jumpers between the pre-out and the amp in, and have the switch in either of the separated positions (subsonic on or off), that 4:1 mismatch can drive the amp into clipping quite easily.
 
When playing music through the unit we are not using the "pre-out" or "power in" we are using the amp in "normal" mode and anything over 1/4 volume there is noticeable distortion especially in the low frequency range.

So we decided to verify clipping and voltage input from the source device and it was less then 120mv and clean (no clipping) while playing a 40hz and 1khz tone.

Then we take the clean input and apply "Aux1" all settings are normal no -/+db anywhere. And for testing only we switched the unit to separated subsonic off mode then tested the "pre out" with nothing attached to the "Power in" at all thus only testing the pre amp at this point and we are getting distortion at 1/4 volume on a testing device while playing the same 40hz and 1khz tones.
 
Both channels?

Now, what about the supply voltages, like Pete asked. +/- 16v, +/- 24v, +/- 42v.
 
Ok I went to his house and listened to the setup in his room since I could only get what sounded like overdrive distortion from my speakers. A few things, I think he had distortion coming from his source device so I found that 60% volume from it was all he could go before he got distortion. Second I think the bass distortion he has is either a bad recording, room dynamics or just plain old overdriving the HPM-100's below 100Hz.

The distortion I was seeing from the preamp was very little. Most likely undetectable to the ear, but I guess from working on car audio I am used to making absolute 0 distortion at each point of a system.

I think he is going to look into an EQ. I recommended room treatment first.
 
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