Just how far do the meters go before clipping a 9090DB?

[Blue Shadow]

Not wanting to overdrive the unit/speakers and take out fuses of more, I'm beating the snot out of the 9090DB that I recently repaired. Got both channels now, offset and bias set and a few caps replaced, all the tuner PS which was way overheated and some that were easy to reach on the main PS board and all on the driver board.

Unit is doing exactly what it should and sounds pretty good (since I using only that today and not comparing) and have the meters wavering around 10w rms (they say they are rms meters). Seems like I don't want to go much louder. Is that true? Meters were not adjusted so they have the original factory setting.

Yes, it is playing loud.

 

[ScottFan355]

Not wanting to overdrive the unit/speakers and take out fuses of more, I'm beating the snot out of the 9090DB that I recently repaired. Got both channels now, offset and bias set and a few caps replaced, all the tuner PS which was way overheated and some that were easy to reach on the main PS board and all on the driver board.

Unit is doing exactly what it should and sounds pretty good (since I using only that today and not comparing) and have the meters wavering around 10w rms (they say they are rms meters). Seems like I don't want to go much louder. Is that true? Meters were not adjusted so they have the original factory setting.

Yes, it is playing loud.

I've been wondering the same thing about my 9090db. I've pushed the meters over 20w with no sign of audible clipping whatsoever. In fact it sounded better than ever, just very very loud!

 

[LBPete]

Considering it's rated at 125 WPC, it's just idling at 10W. You have a long way to go before it clips.

- Pete

 

[LBPete]

When you calibrate the power meters you feed in a 1k sine wave and measure the output voltage across a dummy load while increasing the volume until the rms A/C voltage output is 20v. This voltage represents 50w output and the power meters are adjusted to 50w. When measuring maximum power output you are basically doing the same thing while watching the sine wave on an o'scope. The output voltage should go to about 32V (125W) before clipping.

- Pete

 

[ScottFan355]

According to the tech I got it from it did 156wpc on the bench before clipping.

 

[Blue Shadow]

According to the tech I got it from it did 156wpc on the bench before clipping.

Well we have Bench and Spec power levels and they are definitely not the same. Everything out there does 10-30% more Benched than Spec'd. But that is a good number to know and it agrees with Classic Audio who got 155 benched watts per channel.

Guess I hook up the OC-150a and find out what the meters are telling me.

Because these meters read RMS, according to the manual and I'm listening to music power there is less movement to the meters than one would expect for a VU or dB meter. Additionally, without a peak catch the meter is limited in showing the peaks...but the peaks are the clipping when it happens.

I know the speakers and I use a more powerful amp to drive them and this 9090DB was getting there. I don't want to Hear clipping to know to turn it down, that pops fuses or in worse cases it pops tweeters saving me from having to replace the fuses. If anyone thinks my unit is capable of 10 times the power output based on reading the 10watt meter reading, I don't think it will do that without serious clipping.

I did get the unit warmed up though. Idles at 78°, play a few watts and reaches 150°F and when it is rocking out at 10 up and down from there it reached 192°F. Guess I'll have to beat this thing up some more tomorrow and see what happens.

 

[tarior]

Meters are as much eye candy as anything. Even if they could respond fast enough to accurately reflect musical peaks, your eyes probably couldn't. They are useful in that you get to know where they are when things start to sound a little harsh. I'd rather have them than not, all else being equal.

 

[ScottFan355]

Meters are as much eye candy as anything. Even if they could respond fast enough to accurately reflect musical peaks, your eyes probably couldn't. They are useful in that you get to know where they are when things start to sound a little harsh. I'd rather have them than not, all else being equal.

Hey Tarior loving the Sansui!

 

[tarior]

It's a pretty sweet receiver. The meters have been calibrated as per the service manual, BTW.

 

[ScottFan355]

It's a pretty sweet receiver. The meters have been calibrated as per the service manual, BTW.

Awesome, just curious as to where on the meter you would be comfortable driving them (not counting peaks) on my Hales given that the tweeters are near-unobtanium?

 

[tarior]

Just listen very carefully for audible distortion or harshness. It's a feeling more than a hard number.

 

[ScottFan355]

Just listen very carefully for audible distortion or harshness. It's a feeling more than a hard number.

That's whats scary about the 9090db. I've turned it up VERY loud and it just seems to keep sounding great. Other amps I've used obviously had a gain curve that brought on clipping somewhat abruptly but the Sui seems to just want to go up and up. Luckily I seldom need it to be that loud.

 

[Joel_l]

When I redid my 9090DB, I was able to turn it up to where I could not be near the speakers, that was about 50W. I'd probably have to go outside to get to 125W, but I expect it would sound just fine.

 

[Robisme]

I used to run mine outside for parties at 50 watts on the meters. Gotta watch bass heavy music at that level.
Keep in mind they won't be accurate for all speaker impedances.

Rob

 

[Blue Shadow]

All of these 'too loud to listen to in the same room' mentions aren't very helpful without the speaker mentioned. I'm using 5Ω 85dB sensitivity speakers and they are loud at the 10W meter reading.

Meters are as much eye candy as anything. Even if they could respond fast enough to accurately reflect musical peaks, your eyes probably couldn't. They are useful in that you get to know where they are when things start to sound a little harsh. I'd rather have them than not, all else being equal.

This is why there was a move to the instant LED indications in the mid-70s, a more accurate indication of peaks. Luxman used both on the M-2000, 4000 and 6000 as well as offering their top amp in meterless or metered and offered an LED display. Their receivers had LED power indicators in the late 70s. Other companies did similar and meters were left on some units as eye candy.

Unless one is using a calibrated, known ballistics metering system, it isn't possible to tell what is coming out of the amp. That is the reason I need to add the Crown metering unit to the receiver to get an idea. I don't want clipping unless I change to a different pair of speakers.

 

[Blue Shadow]

While you guys were driving the 9090DB hard, did you happen to get a temp reading of the output sections?

Since I reset all the transistors in fresh heatsink compound I was curious as to the heat that would be generated. Temps are above in post 6 but I was very happy with the consistency of the temps across the heatsinks. generally less than a degree. I don't see that in a number of other units.

 

[Joel_l]

Mine are Dunlavy SM-1s, I think they are @ 6 Ohms nominal and 91dB. This is from a google search.

When I redid my 9090DB, I was able to turn it up to where I could not be near the speakers, that was about 50W. I'd probably have to go outside to get to 125W, but I expect it would sound just fine.

 

[JOMARK911]

There is much more than eye candy at the 9090db power meters. All SANSUI power meters were accurate enough to show peaks. Like PEAK POWER METERS. All of em. Sansui knew and had a special squad back in the days of 70's to implement descent power meters. They were notorious for their hanger for accuracy , they even had serious manufacturers kicked out cause their accuracy was not enough.

 

[whoaru99]

Frankly, this question is nothing about clipping. Speaker drivers can only handle so much power and they don't give a rat's ass where that power comes from. When it's too much power they die.

The only "guarantee" in this sort of question is to never use the speakers or fuse at such a ridiculously low level you'll never get what the speakers can deliver. Otherwise, common sense is the best you can do. If something doesn't sound quite right that's a good sign to turn it down.

 

[KingBubba]

Check your meters with the speakers unplugged. If they still respond, then they are like Pioneer meters. They are there for show, not accuracy.