Setting Limiters on Yamaha P Series Amps

[Bruce Weldy]

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

+1

When you get the reading of 10 volts....is it 10.0 or just 10? If it's just 10, then I don't think you have the meter on the right setting.

[MarcBass]

Two meters, one old, one new. Both auto ranging. 10 odd volt reading is actually 9.xx to 11.xx volts on diferent tests on different days depending on variations of signal strength. The same meters, hooked up the same way give readings up to 20 odd volts at 1kHz on the same Yamaha amps as well as give a range of readings up to 20 odd volts on my little Phonic amp at 60Hz used for breaking in the speakers.

Of note is the information in the back of the Yamaha manual.

• Yamaha EEEngine technology significantly reduces power consumption and heat generation.

1/8 power is typical of program material with occasional clipping. Refer to these figures for most applications.
1/3 power represents program material with extremely heavy clipping.
Test signal: Pink Noise, bandwidth limited from 22Hz to 22kHz

0 dBu=0.775 Vrms, Half Power=1/2 Power Output Level (Rated Power)

It looks like the quoted power figures are for half power. 1/8 Power out at 8 ohms is 131 W and 1/3 power out at 8 ohms is 350 W. 500W into 8 ohms doesn't happen till 1/2 power.

I'm old school and don't like seeing clip lights. Almost seems as though these things are meant to show a clip light if you actually want the rated power!

By my calculations 350 W into 8 ohms is roughly equivalent to 52.9v. Which should be more than enough to drive a 3012LF. If I set limiters to assure the clip light on the amp only ever just flickers I'll be at about 131W which is about 32.4V - quite safe for long life of 3012LF's in a T39.

I could run a band of Pink in a range of say 45Hz to 100Hz through the rig into an 8 ohm load (one of the 18 inch BW's) and measure voltage to test the theory.

[MarcBass]

In BEHRINGER iNUKE NU3000

RichardH wrote:
This is quoted at 450W Output power(20Hz-20kHz) at 4 ohms. I measured just under 20V.
Bill Replied with:

According to Yamaha the 3500 consumes 450w, total, at full output into 4 ohms. Running with 100% efficiency that makes its actual continuous long term capacity 225w/ch, so your 20v figure looks to be spot on.
If you dig deeper into the specs they say 1/8 power into 4 ohms is 148w, and that '1/8 power is typical of program material with occasional clipping. Refer to these figures for most applications.'
They also state that 1/3 power is 393w, and warn that ' 1/3 power represents program material with extremely heavy clipping.'

In other words the rated power figures are just so much piffel.

I think I've found answer!! Thanks Bill.

Ran the 2 T39 standing side by side, no V plate and no limiter with the Yamaha P5000s last night. Did a quick auto EQ with the Driverack PA+. Then played CDs through the desk at volume with a multimeter hooked up to 1 of the T39s.

I was measuring peaks of 120 odd dB a few meters out from the T39s and voltages never spiked past the teens on the T39.

The real question now is should I bother with a limiter at all given the output of the amp?

[sine143]

If you reslly want to test your theory, pull a 3012lf or other premium driver our of the box and hit it with WOT at 30hz. should be perfect break in excursion if its really 10v. if it isnt you should see some hice smoke

[Grant Bunter]

The real question now is should I bother with a limiter at all given the output of the amp?

Yep.
Average continuous isn't peak transient.

And it forms good habit to use a limiter...

[MarcBass]

G'day Grant,

Yep. The engineer in me agrees. Trouble is the engineer wants a measurement to set the limiter to. The 2 options are:

1. run the amp flat out with a 60Hz sine way coming in just below desk clip and set the limiter to just come on, or
2. set limiter by calculation. According to spec sheet amp sensitivity is +6dBu (ie. a 6dB signal when amp attenuation is full clock wise gives full power). Therefore limit output from DriveRack to not exceed +6dBu

Remembering I only got around 120dB SPL with program signal last night and according to the charts in the SPL section here 2 24" T39 are good for 105dB @ 1 w. 15dB increase puts me below the 20 dB max for the lower spec 12" speaker.

SeisTres - yeah mate, haven't had a smoke leak in years. Last one was a Messa Boogie half stack on stage. When we started yelling to the guitarist "You're on fire man" he nodded and thanked us. Once the smoke got thicker he realised we weren't commenting on his lead break!!

[Grant Bunter]

Marc,
Hope this helps...

On the SPL charts page, it says an S2010 loaded T39 will +20dB above the 1W/1m trace, at it's max (which is 28V for an 8 ohm driver).
Then it say the 3012lf is 6dB higher at 56V.

So even in the mid 30's voltage wise, you're still more than the +20db at max (but not as much as +26dB)
Add 6dB for cab doubling and 3dB for a V plate (when you can) and you're near 130dB even in the mid 30 volts. That's loud.
Wall load or corner load and you're going up again.
So, you could still be up over 140dB @50Hz if corner loaded

That's errr awful loud.

I'm running a Jands 920 for BP loaded subs. (350/8ohms, doesn't seem to have the half full power thing going on like the Yammy). On the DCX that's -6dB on the limiter for 35V.
That's set with 60Hz on the channel strip just below clipping, masters on 0dB PFL and that gets the DCX clipping occasionally and briefly and just tickling the limiter, and the J920 clipping every now and again, also briefly.
If you can get to something similar without anything getting bothered, pretty safe to say you'll be pumping at a gig...

[MarcBass]

G'day Grant,

Dragged the rig (2 T39's standing up side by side - no V plate) outside in open air for EQ and a test run. After EQ I ran a few test CD's (Steely Dan etc.)

Had a new true RMS DVM hooked up to one sub chanel as well as the T39 the whole time to get V readings with a load. Also set a limiter on the DriveRack for subs to come in at +6dB. The Yamaha P5000s was set with attenuators full clockwise.

While EQing I saw voltages up into the 20's. When I opened the rig right up (Yamaha desk just below clipping, DriveRack input very occasionally clipping, no noticable clip on the P5000s) I saw voltages spike up into the mid to high 30's. Quick inacurate SPL measurements showed spikes up around the 130dB mark on the subs at 1 meter.

The desk is never driven this hard at a gig. This was an insane setup for the desk. From what I heard and measured I think I have achieved a safety margin. I heard bass clarity that I had never managed to achieve on my old rig. My poor Peavey SP2G's could not keep up and were geting that gritty overloaded sound.

I'll stop here and post the rest of my comments with pics in the review section. The T39's are fantastic. Just the ticket for an open air camp draft gig.

Thanks for the tips, advice and inputs guys. Much appreciated.

[MarcBass]

Wierd Voltage Update:

This thread is quite old but thought I would update for any other Yamaha PS series amp users. I've been using the T39's for a while with this amp setup and just love them. Lately the indoor gigs have been "library" volume shows so I've trimmed back to 1 T39 with 2 Peavey HiSys 12 inch units.

At the last gig things went a bit odd. A new mic pre-amp (TC Electronics Mic Mechanic) for one of the vocalists and a publican wanting band volume to be no greater than 100 dB a meter from the stage. This resulted in me doing silly things on the fly and deciding I needed to re-tune the system, chech gain structure etc.

I took the opportunity to measure the voltage of the Yamaha P5000s at the same time and there it all was!! Good solid voltage upto and over 50v!! I have no idea what I was doing wrong when I started this thread but today's measurement show that all is good.

I had taken a conservative approach as I didn't trust my measurements. Today I lifted the limiters on the driverack to around 52 V to let the Titans do their thing. Given the library volume issues the T39's will be slipped into storage as soon as I get the Omni 12TB's up and running.

Thanks again for the advice in previous posts.

Marc