High level input


From my Mcintosh MC352 I am running speaker cables to my PD80's then jumping to the high level inputs of the built in sub amps. If, for example, the MC352 is pushing 200watts per channel, is half or that power being used to signal the sub amps? Am I wasting power just to send a signal or do the sub amps somehow filter out a line level signal? I hope this makes sense.

Thanks in advance.
nuguy
It seems to me the MC352 is significant overkill for the PD80 loudspeakers. Doesn't answer your question, but it strikes me as a mismatch.
Tvad, with all due respect the PD80s are rated from 1-600 watts per channel, I run 350. I could be wrong but it seemed wrong to run a low powered amp when each speaker houses a 1000 watt sub amp pushing 2-15s.
Max. power input has little to nothing to do with matching an amp to a speaker.

Anyhow, to answer your question, the impedence of a speaker level input on a sub is so high that it demands very, very, very little of the amplifier.

All of your watts are still going to the midwoofers/tweeters.

:)
The PD80s are rated at 101db/1w/1m and 4 ohms. That means you need only 1 watt to produce 101db at 1 meter (104 db at 2 watts, 107 db at 4 watts, and 110 db at 8 watts, etc...). Do you ever listen this loud? If you listen at "normal" levels of 88db-90db, the MC352 is using a fraction of 1 watt to drive the PD80s.

You will likely never use more than 2 watts of the MAC's 350 watts to drive the PD80. The PD80 are rated for high power in the event someone uses them as PA speakers to fill churches, auditoriums or theaters with the necessary volume to recreate live-level sound. You will never approach this volume in your listening room.

The reason you can run a low powered amp...like a SET amp...is precisely because the PD80 have their own 1000 watt subwoofer, and the primary amp doesn't have to do the heavy lifting of driving the woofers.

Hey, if you love the MC352, then by all means use it, but it's overkill for speakers with 101db sensitivity and built in 1000wpc subwoofer amps. My comment about mismatch was simply regarding the power required by the PD80 and the power supplied by the MC352. The comment had nothing to do with the synergy between the two, and the resulting sonics.

Don't take my word for it. Call Ty and verify what I've written. If he says something to the contrary, please correct me. I'm always open to learning something new.
The PD80s are rated at 101db/1w/1m and 4 ohms. That means you need only 1 watt to produce 101db at 1 meter (104 db at 2 watts, 107 db at 4 watts, and 110 db at 8 watts, etc...). Do you ever listen this loud?

Rarely but yes. When I'm in the mood I'll run a couple hundred WPC.
Rarely but yes. When I'm in the mood I'll run a couple hundred WPC.
Nuguy (Threads | Answers)
No you won't. Are you being serious, or is this comment a joke?

Seriously, follow the progression to determine the volume/power required. Start with 101db/1watt/1meter at which your PD80 loudspeakers are rated. For every 3db of volume increase, you double the power. 104db/2 watts, 107db/4 watts, 110db/8 watts, 113db/16 watts, 116db/32 watts, 119db/64 watts, 121db/128 watts, 124db/256 watts...

You'll listen at volume greater than 121db? You know this because you've measured the volume with a decibel meter, or because this is your guess? If you have measured, then you're good to go. If you haven't measured, then we're not discussing this topic from the same page.

What are the dimensions of your room?

Look, my intention was not to irk you, but to simply open your mind to the reality, and to the possibilities. I'm making no judgment regarding your choices.

Please call Ty and verify what I've written. And, if you don't own a decibel meter, then buy one...they're inexpensive...and do some quick measurements.
Just to answer your basic question:
If, for example, the MC352 is pushing 200watts per channel, is half or that power being used to signal the sub amps? Am I wasting power just to send a signal or do the sub amps somehow filter out a line level signal?
Answer: No. The sub ams are not drawing any current from your McIntosh, they only take in the "info" from it (i.e, high level signal) and then amplify it to the woffers.
Tvad , I just wanted to clarify. I completely agree with what you are saying. I had the amp before I bought the speakers and I knew it was loads of power for the PDs. I do like the sound of the Mc and I got a great deal on it, so there it sits. I did want a system that was capable of great sound at high SPLs and the funny thing is, since I got it I normally always listen at very low levels.

Usually when listening the meters hover around 0.35 watts, but every once in a while the headbanger in me comes out and I need a quick fix.

Larry
Tvad, I am serious. I do know the formula for calculating db and I have a meter. I gotta run out now and check on a job. I'll be back in an 2 hours max, take a reading or two and get back to you. My room is VERY strange I'd be glad to email you a pic as well. In fact I would appreciate any other advice you may have.

Talk to ya in a couple hours.....
OK. I used my RTA mic on the behringer and a Extech digital meter. Both the mic and the Extech were placed on the back of the couch approx 14 feet from the speakers. I let the dog out put on some AC/DC and cranked it just shy of peaking out the meters on the Mcintosh. The behringer recorder a peak level of 99.1db. The Extech has an A&C weighting. I'm not sure what that means so I took measurements for both. A came in around 106db and C came in at 120.4db. Why the difference in readings? I have no clue, but it's got me wondering.

Larry
If you can set your MC352 power meters to measure peaks, you might do that, play the same AC/DC track and do another measurement. If the 99db reading is correct, then you might expect to see peaks somewhere between 2-4 watts on the MC352, accounting for the db rolloff at 14'. If the 122 db reading is correct, then you might see peaks over 260wpc. Big difference. The MC352 power meter reading in conjunction with your DEQ2496 and Extech readings should give you a better idea which decibel reading is more accurate.
I actually had the red peak lights flash on the MC when I did the test. Both meters were running with the peak hold activated. The MCs needles were almost stuck at the high end of the scale. If the meters on the MC are accurate I would have been pushing the 350 watt per channel envelope. I know it doesn't seem right but that's what I am reading. Maybe I am doing something wrong. You would think using pink noise would be more stable and give you a more accurate reading, but I dont really want to hear 120db of it.

My room may play a role in all of this as well, you'd have to see it. Custom built home with a WIDE open floorplan.
Something doesn't seem right. There is no reason why the MC352 should ever be close to clipping with 101db/1w/1m loudspeaker, unless you're trying to fill a barn sized space to 124db levels.

I think you should call Ty and explain what's going on and what you've done to test the system.
It surprises me that I am getting such low readings, but believe me it is VERY loud, However, I agree, I will call Ty and report back.

Thanks
Congratulations!
You two have just won the Golden Propeller Hat Award!

http://www.brooklynpeddler.com/images/prophat.jpg

We have yet to get it "goldened" but I assure you that it is in the works (right after cryo-treatment).

:)
06-24-06: Bignerd100
Congratulations!
You two have just won the Golden Propeller Hat Award!
Coming from someone named Bignerd100, I'll take that as a compliment. ;)
The A weighting measures frequencies from 500-10000Hz and the C weighting measures from 32-10000Hz. (specs from Radio Shack's spl meter)Obviously we would go with the C which came in at 120.4 db. I took the measurements with the EQ on and I do have a dip in the mids. If I were to retest with the EQ bypassed the readings would be higher. As for the Behringer reading peaks of only 99.1db, I'm stumped. It could very well be an error on my part.

Thanks everyone for your replies and that's a great hat Bignerd, did you find it while shopping for a new summer wardrobe?:)
Tvad, when we get our new hats does that mean we'll be members of Bignerd's Street Gang?

Don't take it too serious Bignerd I'm only goofing around!

Peace....