Mackie amp for IB??

[beemer533]

I just built my first IB in my new house (thanks to this forum ), it is a line array with 3 Sound Splinter RL p12 drivers.

I was (up until last week) using my old Nady SPA1400 to run the IB, but it started cutting in and out, and for fear of my divers, I retired it.

I had to get it back up and running quickly so I bought a Mackie FR800 amp (all that was in stock at the local shop) for now.

My question is if anybody has used a Mackie?

I haven't seen much about people using these amps, so I was planning on replacing it with a Behringer EP2500. But, it works pretty well and it is very quiet, so I am starting to question weather or not I should bother replacing it.

Any info would be helpful!!

[ThomasW]

Over the years a couple people have used them. Most don't get Mackie do to their cost per watt compared to the Behringers.

[chrisbee]

3 drivers is a very odd number (literally) and may explain why the Nady was so unhappy.

The good news:

3 drivers in series with an individual impedance of 2.5 Ohms upwards would be safe in bridged mode.

Any higher individual impedance would begin to lose output power slightly even in bridged mode.

Bridged mode halves the combined speaker impedance seen by the amplifier.

3 x 2 Ohms = 6/2 (bridged) = 3 Ohms equivalent load per channel. Probably safe.

3 x 4 Ohms = 12/2 = 6 Ohms per channel in bridged mode. Still fine.

But 3 x 8 Ohms in series = 24/2 (bridged) = 12 Ohms per channel. Very safe but may not go as loud as 4 Ohms per channel or 8 Ohms bridged.

An 8 Ohms combined speaker load in bridged mode is equivalent to 4 ohms per channel where most amps are happiest.

Now the very bad news:

Wired in parallel the individual drivers would need to be at least 24 Ohms each to provide a minimum safe 8 Ohms combined load in bridged mode!

Parallel wiring means you divide the individual driver impedance by the number of drivers.

So 24 Ohms/3 = 8 = 8/2 (bridged) = 4 Ohms equivalent load per channel.

But 24 Ohm drivers are probably as rare as hen's teeth.

Let's assume in our worst nightmares that you have used parallel wiring with more conventional drivers:

Let's say they are standard 4 Ohms drivers = 4/3 = 1.333 Ohms combined load. Ouch!

But it gets worse! 1.333 Ohms Bridged = 1.333/2 = 0.66666 Ohms per channel. That's not Nady. It's Downright Nasty!

That's nothing. It can be even worse!

Let's say they are 2 Ohms drivers = 2/3 Ohms in parallel = 0.666 Ohms combined load.

Bridged = 0.66/2 = 0.33 Ohms per channel! Absolutely suicidal!

Even 8 Ohms drivers wired in in parallel are a serious problem. 8/3 = 2.6 Ohms combined load.

Bridged = 2.6/2 = 1.33 Ohms per channel. That's still very unkind to any amplifier and will probably result in overheating or instability.

Though once popular for valve (tube) amps 16 Ohms drivers are rather unusual these days but we'll try them in parallel just in case we can use them:

16/3 = 5 ohms combined load. 5/2 bridged = 2.5 Ohms per channel. That's still a lower impedance than most amps like to see at high and lengthy listening levels.

No series-parallel wiring combination is possible with an odd number of drivers. The individual drivers will not be evenly balanced in their share of the power available.

[beemer533]

Whoa!!

That's a lot of very helpful info...... thanks for taking the time to enlighten me!!

I reread my OP this morning, and forgot a little detail: with the Nady hooked up, I just had 1 RL p12 D4 hooked up.

So the Nady (running in Parallel mode) was only seeing 4 ohms per channel.

Now the fun begins; when I originally built the line array plate I just had the 1 speaker, and for future expansion I made the plate big enough for 2 more 12" on either side.

This was about as much as the wife could take

So I've been trying to get 2 more D4's, but I am sure everybody here is aware of the issues Sound Splinter is having with their supplier. So when Mike emailed me that D2's were available I jumped and bought 2 more.

They will be here Friday, and I have been trying to decide how to wire them. I wasn't going to ask the question until I was staring at them in my living room, but Chrisbee has gotten there before I could.

The other question I have at this point is weather it makes sense to run the amp bridged or like I have right now (1 driver connected) in parallel mode?

[goofus]

I have 7 of them. I live just a few miles from the factory, so I can pick them up on craigslist for about the same price as a comparable Behringer.

I'm running 2 M1400's and 3 M2600's for my mains and surrounds. This is a discontinued line, but from what I can tell, it seems to be built better than the current line. The switches and knobs movement is glassy smooth and the 3U case on the 2600 looks massive. Additionally they have some adjustable high and low pass filters and can be daisy chained, but I don’t think anyone here would have a need for that. The downside is that they have an odd cooling configuration. They intake through the front, and exhaust through the sides. It doesn’t make any difference to me, but it might for some. Also, the M2600 fan is pretty loud. I’ve never heard a Behringer amp, but based on descriptions I suspect the noise is similar. The upside though, is that the service manual describes a method to verify the fan speed when at max temperature. I’m going from memory, but I think it involved shorting a jumper and adjusting a pot while monitoring voltage. I suspect this will allow me to turn them down, but I haven’t verified it yet. The other issue is that the M2600’s come with nema 20 power cords, so they won’t plug into a typical outlet in your home. Mackie does sell an adapter though, so it’s not a problem running it on a regular 15 amp circuit. I just spliced new ends on my plugs and run all 3 of them on the same 15 amp circuit.

I also have 2 FR2500’s for my IB. This is the current line. It has a much cheaper feel to it then the older ones. These are factory refurbs, but the gain knobs feel like they are full of sand. Otherwise they are great. Just a basic barebones amp with no unnecessary features. The fans are extremely quiet, but not completely silent. I originally picked up 2 of them to run 4 Fi 18’s at 4ohms per channel. I have found that a single one has no problem running all 4 drivers at 2ohms. In fact I think somewhere in their marketing material they state “Runs at 2 ohms all day long”, or something like that. That might be why your FR800 is handling what toasted your Nady.

Sound quality-wise, I can’t tell the difference between any of these, so if I started from scratch, I would probably stick with the FR line. I have the impression that Behringer amps are questionable with 2 ohm loads. If that’s the case, you might be able to argue that a single Mackie would be more cost effective, if the application required 2

[beemer533]

Very nice rack. Thanks for the info!

I actually picked up my FR800 for $250, so it seemed like apretty decent deal.

How long have you had your FR2500s? It doesn't sound like you have had any issues with them yet......

I plan on keeping the overall load at 4 ohms, so that shouldn't be an issue.

[beemer533]

Well, everything is now hooked up; here is what I ended up with:

I exchanged the FR800 with an FR1400 (on sale for $299).

I wired the vioce coils on each of the 2 D2s in series to give 4 ohms each, then I wired the 2 D2 in series to give 8 ohms. I wired the vioce coils on the D4 in series to give 8 ohms.

I then connected both in parallel to give a final impedance of 4 ohms. I have the Mackie in bridged mode and it sounds great so far!

I still need to hook up my BFD and tune for my room, but I am very happy with the results so far. ;D

[edfowler]

I upgraded my Beringher 2500 to a Mackie M2600 and it made a world of difference in the sound. To me it is much more musical and not as harsh sounding.

[goofus]

How does the fan noise on the Behringer compare to the M2600? My M2600s are pretty loud. The fans sort of make a clicking sound too, sort of like a card in the spokes. Quieting them down is on my 'to do' list.

I normally don't get a lot of time to watch movies, but on Friday a bunch of us left work at noon and had a Bond party at my place. We did a Casino Royale, and Quantum of Solace double feature. Both movies were played back to back at reference levels and all of the amps held up fine. I think my M1400s run at 10 ohms / channel and my M2600s are at 8 ohms, so I really didn't expect any problems from them anyway, but my FR2500 ran my subs at 2 ohms without issue as well (and with a much quieter fan).

As far as sound quality goes, I have nothing to compare them to, but they sound great to me.

[johnvb]

Just want to make a comment about a couple of Mackie FR1400s (floor models on sale, from GC) I picked up a while back. Even though right now I am not using them for IBs, the plan is to do so in the future.

The dealer had them set up/running in their "showroom", along with the competing (price wise), Behringers and QSC amps. The Mackie amp fans were significantly quieter. I would compare the fan noise on the same level as a PC.

Also, the Tapco Juice amps are said to be identical (internally) to the Mackie FRs. I run my Mackies in an A/V closet, along with my audio PC hard drive system, so have no noise issue, but here's a post from AVS where someone modded a Tapco, including fan mods:

www.avsforum.com/avs-vb/showthread.php?t=843202

[beemer533]

I would agree, I haven't heard the EP2500, but the 1500 is quite loud. Both the FR800 and the FR1400 I have are very quiet.

I will hopefully get the chance to tune the IB tomorrow and will post the results.........