Setting Limiters on Yamaha P Series Amps

[MarcBass]

I know this subject has been done to death but I have an odd problem setting limiters on Yamaha PS amps.

The rig is a Yamaha MG sereies desk followed by a DBX Driverack PA+ then a Yamaha P5000S amp hooked up to a pair of T39's with 3012LF speakers. The Driverack is set for stereo top and mono sub.

Following the instructions in this section I'm flat out getting 10v with a 60Hz signal. All EQ sections of the Drive rack are off. All the fancy switches on the back of the Yamaha are off except, the parallel switch. I've tried using an alternative tone generator just to be sure my signal is ok. (It also sounded like 60Hz when I ran it at low volume through a titan.)

Has anyone experienced this issue? Does anyone have any advice?

[Grant Bunter]

Marc,
Have you tried to input a 60Hz tone directly to your amp without the mixer and driverack and then measuring voltage?
ie tone generator on a laptop straight into TRS 1/4" input.
If you get more than 10V that way, you at least know your problem is "up the chain".

I notice the specs for the yammy 5000s, measured 20Hz to 20K give 500W/channel at 8 ohms, or 63V, so i'd guestimate you should be limiting 6 or 7 dB to get 50V...

[MarcBass]

Ahh!! Great advice thanks Grant. Putting 60Hz at line level direct to the Amp is the one thing I didn't try.

The guestimate (limt 6 -7dB) was where I thought I may end up having to go. Or, swap over to a Yamaha P3500 for the T39's.

I'm running a pair of Peavey SP2's on the P3500. I can get a volt reading on it with the same signal chain at 1kHz!

The DVM also worked fine setting an old Phonic Max 500 for 10V at 27.5 Hz (same tone generaltor) to burn in the 3012LF's. Which makes me wonder about the Yamaha amp.

[Grant Bunter]

No worries!

Hopefully the Driverack users will chime in.

Hope you get it sorted, looking forward to seeing your impressions of your cabs...

[Bruce Weldy]

Where are you hooking up the tone generator on the mixer?

Are you getting the master fader to run the output into the yellow on the board?

Are the gains in the crossover section of the driverack set to -0- for the lows?

Are the crossover frequencies set properly?

[MarcBass]

G'day Bruce

Where are you hooking up the tone generator on the mixer?

Tone signal is going into a chanel

[quote="Are you getting the master fader to run the output into the yellow on the board?[/quote]

Output from the board is on the yellow before the red. Have tried it with the red just lit as well. same result.

[quote="Are the gains in the crossover section of the driverack set to -0- for the lows?[/quote]

Yes

[quote="Are the crossover frequencies set properly?[/quote]

Maybe not perfect: Low 45Hz LR24, High 100Hz LR24. While I doubt it will have any effect on this issue; do you have a recommendation for filter type at 100 Hz for the low and high curve? I have heard of blokes using a different XXover frequency on the high curve to the low and using different filters and slopes.

Grant, just ran a signal direct to the input of the Yamaha. Same result. Tried 60 and 80Hz. The amp was clipping by the time I got to 10V. This is all with no load on the amp. I also ran a 1KHz signal direct to the amp input and got an instant 30 odd volts.

Went back to the 80Hz signal and flicked the switches on the back of the amp to "subwoofer", setting the frequency knob for 125 and got the same result (10 odd volts) as before with the switches on the back set to off.

It's starting to look like the amp is the issue??

[sine143]

sounds like its time for a new volt meter.

[Grant Bunter]

Since the result is no different when directly putting in 60Hz or going via desk/driverack I'm inclined to think it's the 5000s amp.

The specs at 1K say you should be getting 750W/8ohms, or 77V, so if you're only getting 30V there ten something is amiss.

Try the 3500 and see what happens there...

[Tom Smit]

Went back to the 80Hz signal and flicked the switches on the back of the amp to "subwoofer", setting the frequency knob for 125 and got the same result (10 odd volts) as before with the switches on the back set to off.

It's starting to look like the amp is the issue??

What would happen if you left those switches alone?

I'm thinking that, since you are controlling the x-over with the Driverack, you don't need to do it with the amp. IOW, leave the switch to "full-range?", and let the Driverack handle the chores.

[Bruce Weldy]

Went back to the 80Hz signal and flicked the switches on the back of the amp to "subwoofer", setting the frequency knob for 125 and got the same result (10 odd volts) as before with the switches on the back set to off.

It's starting to look like the amp is the issue??

What would happen if you left those switches alone?

I'm thinking that, since you are controlling the x-over with the Driverack, you don't need to do it with the amp. IOW, leave the switch to "full-range?", and let the Driverack handle the chores.

+1

Do not do any processing at the amp. Set everything to full range, turn off any limiters, or other switches.

[Bruce Weldy]

Just looked at a pic of the back of that amp. Turn those frequency knobs all the way to the left and set the switches to off.

[MarcBass]

Thanks Guys. I started out with on amp processing off. Intend to leave it that way. I agree, let the Driverack do its job.

Have got hold of a new meter to try out. My meter has served me well for 13 odd years, I'd hate to think it was the issue but it's sure cheaper than a power amp to replace.

Grant, I think I did try the P3500 and got a similar result. I also threw an old Peavey PV1.3k (4RU and 55lb, part of why it isn't used on the road these days) in very quickly and got a similar result. I didn't trust the test with the PV as it is very old with TS jack inputs and I was rushed. I should say that I have been driving a pair Peavey 118's with the P5000S with no problems. 118's are direct radiator BW 18" with a program rating of 500W. Not overly power hungry but prove that the amp is putting something out.

Will see how I go with a new meter and let you know.

Thanks again for the input and sugestions.

Marc

[Grant Bunter]

Got me stuffed it has.
I hope it's the multimeter then.

A great (bass player) mate of mine (who was orignally from where I live now, he's in Brissy now) used to use 2 x 15 BW 400W's with his banging SWR head, in his direct radiator cab, on bigger stages when we were in a band together.

Just weird to me it will run your 118's without a prob (love to know what voltage your getting there) but won't run a 60 Hz sine wave...

[MarcBass]

New multimeter. Signal direct from desk, running at the bar below red on main output, into amp.

Both Yamaha amps read around 10 v at 60Hz and in the low to mid 20's at 1kHz.

All signal processing on amp is off. Signal from desk is straight, no eq, pads or anything. Starting to think it's part of the Yamaha fancy power saving system!

Next test is to measure voltage with a speaker hooked up for load I suppose. Gonna have to do that out-doors. 60Hz at full tilt indoors is too much .......

[DJPhatman]

I suggest you test your voltmeter first. If you are mistaken by a faulty meter, the results could be bad.