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Rolls PM55 Headphone Amp Question


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I just purchased a Rolls PM55 for use as my monitoring while playing drums. I have a question, as I have never used one before. We have a Presonus Studio Live 16.4.2 Could I use a Subgroup for the drums and send that signal to the Mic in for my mix (nothing going to Mic thru) and then use an Aux send in the Monitor in for everyone else?

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Yes, BUT here's the catch, you are going to need a Limiter inline between the Mixer and the Headphone amp.

Rolls makes a program limiter that sells for around $60. That is all you need.

The reason is - if a mic gets dropped or kicked over - when it hits the ground, that thump could cause a volume spike that would damage your hearing.

(I use a Rolls 6-channel headphone amp for the same thing, and I use a dbx 166xl for the limiting.)

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Yes, BUT here's the catch, you are going to need a Limiter inline between the Mixer and the Headphone amp.

Rolls makes a program limiter that sells for around $60. That is all you need.

The reason is - if a mic gets dropped or kicked over - when it hits the ground, that thump could cause a volume spike that would damage your hearing.

(I use a Rolls 6-channel headphone amp for the same thing, and I use a dbx 166xl for the limiting.)

 

Ok, great. I supposed I could just use another Aux send instead of a Sub Group if I have an extra. The Presonus has an onboard limiter that can be applied to the Aux and Subgroup sends. Thanks for the help. Anything else I should be thinking about?

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... you are going to need a Limiter inline between the Mixer and the Headphone amp.

...

The reason is - if a mic gets dropped or kicked over - when it hits the ground, that thump could cause a volume spike that would damage your hearing.

 

 

Yes, but the limiter will only help you if you can set it correctly. The question is how do you set your limiter to give you a specific max spl level in your headphones?

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Yes, but the limiter will only help you if you can set it correctly. The question is how do you set your limiter to give you a specific max spl level in your headphones?

 

 

Good question how would you determine the max spl level? Can the headphones get louder then what the max spl is rated if a mic were to get dropped?

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Yes, but the limiter will only help you if you can set it correctly. The question is how do you set your limiter to give you a specific max spl level in your headphones?

 

I set mine at Infinity:1 generally somewhere between -6db & -10db and have never had any problems with it. One thing I realized early on - is that even when I was using cheap Koss "sponge" type Earbuds - they cut out a TON of sound, so I have never had to listen at loud volumes - plus, I am generally behind the amps - they are about as far out as the front of my kick drum, so I am almost in a "null spot" - there is a little volume coming out the back, but the earbuds block most of that out. The last bass player I was playing with played really loudly, and I could not get him to either turn the low end down, or just not even use the 15" speaker; he had two 4x10" boxes, but normally used a 4x10" and a 1x15" box when we played out because he liked the low end coming from the 15". I, on the other hand, was constantly battling a standing wave/rumble around 100hz because of that 15". So on his side of the stage (my right) I constantly heard it. I loved the guy to death - we've been friends for 20+ years, but man was he hard headed, and I ended up switching to this set up. I didn't even put bass in the monitors half the time - normally I just had guitar, vocals, kick & snare.

Eventually I quit the band because it was just a hassle; those guys thought we were playing the Coliseum when we would be in a 100 person bar. I mean - I cut my kit down from a 11-piece double bass RUSH sized kit (with 6"-20" toms and a Gong) back to 1 kick with a double pedal, 1 rack tom, and 2 floor toms.... but there was no way they were going to play out with less than full stacks on each side.:rolleyes:

 

I should have started taking the full kit out just so they wouldn't have room on the stage for their amps. LOL

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Good question how would you determine the max spl level? Can the headphones get louder then what the max spl is rated if a mic were to get dropped?

 

 

As long as you make sure that the Limter's threshold is set up to Limit long before it hits the headphone's max spl, I would say no, and I'll trust using the dbx over the kinds of limiters that are built into the Wireless receivers any day of the week.

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Too bad I don't trust Digital Mixers I've so wanted to go that route....but i have had so many problems with Computers that I don't trust digital mixers.

 

 

Sorry OT

 

I know the feeling with computers but I must say that digital mixers are quite reliable (almost no computer like glitches about them). I have the most experiance with Yamaha products but ouside of operator error, I can only think of a few instances where I've seen digital boards lock up or lose it. By far and away the majoriety of national acts we do spec a digital console on their rider. You shouldn't be afraid of failure (I'd say the failure rate is possibly lower than a lot of analog consoles - it'd be an interesting statistic to know).

 

The only issue I see with digital boards is speed of operation and the lack of standardized control surfaces. At their best they still aren't quite as fast as an analog board (IF the UI is good they can come awfuly close though) and there is a small learning curve for each board (there are similarities but no real standards yet - some mixers the learning curve is steeper than others). The advantages are HUGE and obvious.

 

just .02 worth

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As long as you make sure that the Limter's threshold is set up to Limit long before it hits the headphone's max spl,

 

 

What does that have to do with hearing protection? Your hearing could be damages WAY before you ever hit the limiter.

 

What you need to do is set the limiter to limiter before you reach a damaging level to your hearing. The question is how do you know where that is? It is very difficult to determine because you have to take into account max level and duration at the same time.

 

Your point has some validity, but in practice you've done nothing to insure you've protected yourself.

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What does that have to do with hearing protection? Your hearing could be damages WAY before you ever hit the limiter.


What you need to do is set the limiter to limiter before you reach a damaging level to your hearing. The question is how do you know where that is? It is very difficult to determine because you have to take into account max level and duration at the same time.


Your point has some validity, but in practice you've done nothing to insure you've protected yourself.

 

 

Using the parameters you are going by, you should NEVER even listen to music - because you never know if you are listening at a volume level that is damaging.

 

By the same token, how do you set it for an IEM? IF I turn the limiter on the IEM on and play with it turned up full blast, how am I going to know for sure that I am protecting my hearing? The same goes for Monitoring with speakers - what if I play with a large wedge, or an 18" Sub and 15"+!" box on top with 500 Watts driving each box less than 4 feet away from me for a monitor rig?

 

The Limiter is simply to control audio peaks/spikes.

 

As I said, I don't have them very loud. I actually listen to music with earbuds on my PC louder than I do the IEM, so if anything - I'm doing more damage from simply listening to music for pleasure than I do monitoring when I play. And when I did use a wedge (I have a Peavey 2445 - 2x12"+1" wedge from back in the 80's - loaded with Black Widows and a 22T driver), it was much louder than the IEM's are.

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Using the parameters you are going by, you should NEVER even listen to music - because you never know if you are listening at a volume level that is damaging.


By the same token, how do you set it for an IEM? IF I turn the limiter on the IEM on and play with it turned up full blast, how am I going to know for sure that I am protecting my hearing? The same goes for Monitoring with speakers - what if I play with a large wedge, or an 18" Sub and 15"+!" box on top with 500 Watts driving each box less than 4 feet away from me for a monitor rig?


The Limiter is simply to control audio peaks/spikes.


As I said, I don't have them very loud. I actually listen to music with earbuds on my PC louder than I do the IEM, so if anything - I'm doing more damage from simply listening to music for pleasure than I do monitoring when I play. And when I did use a wedge (I have a Peavey 2445 - 2x12"+1" wedge from back in the 80's - loaded with Black Widows and a 22T driver), it was much louder than the IEM's are.

 

 

 

Valid points by both of you. How does one determine "safe", both with headphones, and open-air loudspeakers?

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The Limiter is simply to control audio peaks/spikes.


 

 

So you do know that common limiters allow peaks to pass through for at least the attack time on the limiter's setting. OTOH the headphone amp itself has a hard limiter that does cut off the peaks ... it's called clipping.

 

Craig's question is exactly where I was hoping the discussion you go. There is not a simple one size fits all answer so what I'm hoping will come from this discussion is that users will question their own systems and ask themselves IF they are getting any valid protection. Don't for a minute believe that just because you have a limiter you are getting ANY protection, you may not be.

 

Now if you set your system too low there is no problem at all ... but again the question is where IS too low?

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I'd say there is no guarantee that you're protecting your hearing even with the factory limiters built in to regular I.E. beltpacks. The limiter will stop peaks at a set voltage but the question is how does that voltage translate into SPL? The determining factor would be the efficiency of your earbuds/headphones (as well as other things like the volume of your ear canal & how far in they are inserted). If they're anything like speakers they could easily vary by + - 10db or more (I know I LOVE the sound of AKG K240M headphones but they are NOT very efficient (maybe the 600 ohm impedence has something to do with it)). I guess the trick would be to set the threshold of the limiter at below some predetermined SPL (say 90 "A" weighted) but how would you measure what's in your ear canal with the buds in? hmmmm

 

my .02

 

As I digress, my HP amp always hits it's voltage rail well before the headphones are being driven near their max. I've even toyed with building a 10:1 impedence matching transformer box to see if I could jump the voltage up. Of course The new version of the same phones is something like 30 ohms (but I understand they don't sound the same).

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