Portable PA systems

It's all about the equipment

Moderators: Mr Awesomer, JesseMiner, CafeSavoy

Message
Author
User avatar
Mr Awesomer
Posts: 1089
Joined: Mon Nov 18, 2002 10:21 pm
Location: Altadena, CA
Contact:

#46 Post by Mr Awesomer » Tue Feb 12, 2008 4:11 pm

Nima wrote:
Toon Town Dave wrote:Something with detachable speakers that can be mounted on tripods would also help.
You mean Speaker stands right? I don't think that many tripods can handle a 15-20 lb (minimum) speakers that would cost you less than speaker stands.
Speaker stands are typically tripods.
Image
Reuben Brown
Southern California

Surreal
Posts: 402
Joined: Fri Aug 25, 2006 3:31 pm
Location: Winnipeg, Manitoba, Canada

#47 Post by Surreal » Tue Feb 26, 2008 1:50 pm

Informative reading: PA system buying guide

straycat
Posts: 264
Joined: Tue Apr 10, 2007 11:11 am
Location: Durham, UK

#48 Post by straycat » Wed Feb 27, 2008 11:54 am

Cyrano de Maniac wrote:For self-powered speakers, I've used Mackie SRM450 units or their smaller bretheren (or older versions) from time to time for both DJ'd and live sound gigs (not all dances, mind you). I have absolutely no complaints about them, and heartily endorse them.
Another endorsement from me for Mackies - we've been using the 'smaller brethren' (SRM350) for over a year now, and I absolutely love them. Sound quality is excellent, and the far-too-good-to-be-true blurb that the company spouts about their ability to fill a room with great sound actually seems to work - probably the closest we've found to just-stick-em-anywhere-and-forget-about-em speakers.

Toon Town Dave
Posts: 661
Joined: Wed Nov 20, 2002 2:52 pm
Location: Saskatoon, Canada

#49 Post by Toon Town Dave » Wed May 14, 2008 11:36 am

I just picked up a Mackie SRM150 on the weekend and I'm really pleased with it. It's the baby bretheren of the 3/450's.

It's really small (about the size of a toaster), and pretty light with a built-in mixer. The mixer has 2 mic inputs one of which can be used as a high impedance input for a guitar or something. The 3rd mixer channel is a stereo line-level input (RCA connectors).

Multiple units can be daisy chained together with one as the master or they can be used just like the 3/450's with a mixer as the source. They can also feed a 3/450 if you need more power. Quite handy to eliminate a mixer from the equipment roster. They also mount on mic stands which are a little less bulky that traditional speaker stands.

Great for lessons or dances in a small venue where a 350 is overkill. Way more compact than the equivalent Passport system. My only complaint is that they don't take a DC power source or outdoor dance events. I'm going to try running one off a 300W inverter.

My only complaint is they are a little weak in the lows. I'm not sure if this is by design or if the cones are a little stiff because it's new. There is only one 5" speaker rather than a woofer and tweeter like the larger ones.

Surreal
Posts: 402
Joined: Fri Aug 25, 2006 3:31 pm
Location: Winnipeg, Manitoba, Canada

#50 Post by Surreal » Wed May 14, 2008 10:40 pm

Toon Town Dave wrote:My only complaint is they are a little weak in the lows. I'm not sure if this is by design or if the cones are a little stiff because it's new. There is only one 5" speaker rather than a woofer and tweeter like the larger ones.
Weak for their size, or in general?

SoundInMotionDJ
Posts: 154
Joined: Wed May 30, 2007 8:27 pm

#51 Post by SoundInMotionDJ » Thu May 15, 2008 6:06 am

Toon Town Dave wrote:My only complaint is they are a little weak in the lows. I'm not sure if this is by design or if the cones are a little stiff because it's new. There is only one 5" speaker rather than a woofer and tweeter like the larger ones.
The cones will loosen up with use. It takes some time for a new cone to really break in. In theory, it will continue to change over the lifetime of the woofer...but in reality almost all the change will happen in the first 24 or so hours of use. I measure about 3dB more output from new woofers after about 100 hours of use.

That said, a 5" speaker at head height is not able to couple to the ground at all...and it likely 180deg out of phase at between 50Hz & 60Hz. That is not good for lows.

Despite the wishes of people everywhere, a separate subwoofer, that is wall or corner loaded is still the best way to reproduce low end content in music.

--Stan Graves

Surreal
Posts: 402
Joined: Fri Aug 25, 2006 3:31 pm
Location: Winnipeg, Manitoba, Canada

#52 Post by Surreal » Thu May 15, 2008 8:40 am

Why does the sound get louder after breaking it in? (I suppose the engineer in me wants to know why the stiffer cone doesn't produce as much sound)

SoundInMotionDJ
Posts: 154
Joined: Wed May 30, 2007 8:27 pm

#53 Post by SoundInMotionDJ » Thu May 15, 2008 9:44 am

The woofer will break in with use because the web that supports the cone will be flexed and worked through a range of motion. This allows for more woofer movement with the same input energy. That is why the woofer gets louder with use.

--Stan Graves
Last edited by SoundInMotionDJ on Thu May 15, 2008 3:23 pm, edited 1 time in total.

Toon Town Dave
Posts: 661
Joined: Wed Nov 20, 2002 2:52 pm
Location: Saskatoon, Canada

#54 Post by Toon Town Dave » Thu May 15, 2008 11:57 am

SoundInMotionDJ wrote:That said, a 5" speaker at head height is not able to couple to the ground at all...and it likely 180deg out of phase at between 50Hz & 60Hz. That is not good for lows.
Huh? How can the out put of a single speaker be out of phase let alone out of phase at particular frequencies? What do you mean "couple to ground", do you mean in a mechanical or electrical sense?

The frequency response spec for the SRM150's is 100Hz - 17.5KHz so I'd expect little at 100Hz, and nearly nothing at 50Hz anyway.

SoundInMotionDJ
Posts: 154
Joined: Wed May 30, 2007 8:27 pm

#55 Post by SoundInMotionDJ » Thu May 15, 2008 12:59 pm

Toon Town Dave wrote:
SoundInMotionDJ wrote:That said, a 5" speaker at head height is not able to couple to the ground at all...and it likely 180deg out of phase at between 50Hz & 60Hz. That is not good for lows.
Huh? How can the out put of a single speaker be out of phase let alone out of phase at particular frequencies? What do you mean "couple to ground", do you mean in a mechanical or electrical sense?
Ahhh...so many questions...here goes:

By "coupling" I am referring to "boundary loading". The floor is a boundary. If the source is within 1/2 the distance of the radiating plane, then the boundary loading "coupling" will occur. For a 15" direct radiator, that means within 7.5"...which can be rounded to "on the ground."

Below 100Hz, sound is "omni directional."

At 40Hz, a sound wave is about 28ft long.
At 100Hz, a sound wave is about 11ft long.

If a reflective surface is 1/4 wavelength away from the source, then the reflected wave will be 180deg out of phase (i.e. 1/2 wavelength total travel).

At 40Hz, 1/4 wavelength is 7ft.
At 100Hz, 1/4 wavelength is 2.8ft.

So, the Prime directive of speaker placement is "never put a sub between 2.5ft and 8ft from a boundary".

If you have PC speakers with a separate sub woofer...try this experiment. Place the sub on the floor, and point it into the corner. Keep the sub about 3-4" from the walls. Notice the increased low frequency sound.

Here is a distance -v- frequency chart for boundary cancellation:

http://www.padrick.net/LiveSound/CancellationMode.htm
Toon Town Dave wrote:The frequency response spec for the SRM150's is 100Hz - 17.5KHz so I'd expect little at 100Hz, and nearly nothing at 50Hz anyway.
Well then...nevermind. That would certainly explain the lack of low end.

--Stan Graves

Toon Town Dave
Posts: 661
Joined: Wed Nov 20, 2002 2:52 pm
Location: Saskatoon, Canada

#56 Post by Toon Town Dave » Thu May 15, 2008 4:29 pm

Alright, between the explanation, the link, this speaker size discussion, I now sort of understand what you're talking about. At least the science behind it.

Perhaps I need to go experiment in the under-utilized anechoic chamber across campus.

SoundInMotionDJ
Posts: 154
Joined: Wed May 30, 2007 8:27 pm

#57 Post by SoundInMotionDJ » Thu May 15, 2008 7:30 pm

Toon Town Dave wrote:Alright, between the explanation, the link, this speaker size discussion, I now sort of understand what you're talking about. At least the science behind it.

Perhaps I need to go experiment in the under-utilized anechoic chamber across campus.
Read L Ron Hoover's comments...ignore the rest.

--Stan Graves

Surreal
Posts: 402
Joined: Fri Aug 25, 2006 3:31 pm
Location: Winnipeg, Manitoba, Canada

#58 Post by Surreal » Fri May 16, 2008 1:47 pm

Ugh, flashbacks to undergrad acoustics & vibrations courses.

I actually got all of that, though it took a minute for my brain to rewire itself. I usually just stick my speakers next to the wall, not so much for the acoustic factor, but so people won't bump into them (I swear, there must be some sort of relation whereby the newer the speakers, the more people that accidentally bump or kick them).
SoundInMotionDJ wrote:The woofer will break in with use because the web that supports the cone will be flexed and worked through a range of motion. This allows for more woofer movement with the same input energy. That is why the woofer gets louder with use.
Oh, that makes sense. At first I thought you meant the actual cone got softer, which didn't make sense to me.

--Stan Graves
Toon Town Dave wrote:Perhaps I need to go experiment in the under-utilized anechoic chamber across campus.
Those rooms are great for napping.

User avatar
hepcat72
Posts: 31
Joined: Sat Jan 21, 2006 10:06 am
Location: Buffalo, NY
Contact:

ion?

#59 Post by hepcat72 » Tue Jun 17, 2008 8:29 am

Hi,

I've been looking into speakers for a dance of around 50-100 people. I looked into the Fender Passport because I've seen those in use elsewhere. But I've heard the audio quality is better with other systems. Someone I spoke to this weekend recommended either the Ion (Ion Audio iPA03 Portable PA with iPod Docking (IONIPA03)) or something made by JBL (they weren't specific). Anyone have any opinions about Ion or JBL as compared to Fender?

Thanks,
Rob

Toon Town Dave
Posts: 661
Joined: Wed Nov 20, 2002 2:52 pm
Location: Saskatoon, Canada

#60 Post by Toon Town Dave » Tue Jun 17, 2008 8:41 am

If you're looking at Fender, I'd suggest taking a look at a pair of Mackie SRM150's for similar power and functionality at a similar price with better sound quality than a passport 250 (and much smaller and lighter). I'm really happy with mine. The peavey Escort is similar. If you read back on this thread (or maybe it's a different one), the reviews of the Passport among swing DJs is a mixed bag of love it and hate it. I hate it.

For a room of 100, I'd look at something a little bigger. Certainly the JBL Eon G2 series or the Mackie SRM350 and SRM450 or similar models from EV. You'll probably need a small mixer as well but you should be able to put together a great system for less than $1500 new.

Locked