Bargin Pro Amplifier (1 Viewer)

[Rob Formica]

Bill: I jealous... my amp has reached it's american destination, but still has to get sent here... I'm not complaining , as it was real nice to have someone help me out like that. I'm actually in a similar situation where my project sub is still just a "plan"... I've just ordered a AV15 which I'll put in a ported 6ft3 enclosure... but shipping for the driver won't be until this summer. Thanks for the info about the MPC subsonic filter... saves me the panic as well Actually, at 8Hz, wouldn't it act as an effective rumble filter?

Al: I was just wondering how you were planning on using your sub? The use of an external x-over is somewhat optional if you are using a processor/receiver with a Sub out... but is essential if you're doing 2-channel audio without a pre/pro. I've dialled out my current sub's x-over (by putting it at it's maximum setting) as I set my preamp's output much lower. My test tones have confirmed that the lower setting is controlling it.

 

[Bill Fagal]

Al,

I haven't heard it, but I like the looks of the Behringer CX2310. At about a hundred bucks, it seems like a great value. But Rob's got a good point about the option of just using receiver bass management.

Rob,

Good luck with your AV15. I'm sure you'll get plenty o' joy out of that alignment. I'm going to experiment with a load of bargain Kicker C15c4 and C18c4 drivers I picked up for cheap a couple years ago. Though they're autosound drivers, they've got the specs to be quite decent HT drivers, IMO. So I'm thinking about either a crawlspace-mounted manifold with 8 of the 15-inchers, or two of the 18-inchers in 2ft^3 ELF (or LT) EQd sealed boxes. I'm leaning toward the IB if my wife will agree to the largish hole in the floor.

BTW, Yes, the subsonic filter is just another name for a rumble filter.

Bill

 

[Al Garay]

I will be using the AV15 for a 2.1 stereo/HT system. I have a Bent Audio TX102S passive pre-amp and AKSA monoblocks driving a pair of Ellis 1801 speakers.

I do not have a HT receiver. So, I'm searching for a good deal on pro-amp and active crossover. The JBL MPC300 plus a Behringer CX2310 would cost about $300. And I'm wondering if the Rhythmik A350 for $150 would work well enough.

Does Behringer make a EQ with an active crossover?

Al

 

[Bill Fagal]

You've got a pretty fly setup there. Sure, the Rhythmik will probably let your AV15 more than keep up with your mains. It all depends on your loudness expectations. For my experiments with sub-resonant boxes, I want all the watts I can get (for dirt-cheap).

Check out Behringer's website. They've got some tasty stuff like the DCX2496, a digital XO w/ parametric EQ, and the DEQ2496 digital EQ with about all the bells and whistles you can shake a stick at. Both are bargains for what they do, but still pricey from my extremely frugal POV.

 

[Bill Fagal]

For those interested in the MPC300 conversion, I've learned that QSC has the 30A thermistor for the conversion in stock, part # RE-000170-NR. The price is $4.35 each. The MPC200 doesn't need the thermistor.

The rest of the conversion looks dead simple: New power cord, move a few friction connectors to different terminals on the power PCB, and swap in higher-current fuses.

 

[Al Garay]

Bill,

I got my AV15 today from Chris Hunigan... It is one impressive looking woofer. Very heavy. I cannot go with the Rythmik. I am now thinking of going with the JBL MPC300 and following the conversions.

I appreciate your help in ordering the additional parts for the voltage conversion. I know I need to order the 30A thermistor... what else?

I wonder if JBL has an inexpensive active crossover I can use? Otherwise, I will be looking at the Behringer CX2310 or a used Rane AC22/AC23/AC23B.

Thanks,

Al

 

[Rob Formica]

Bill, just wondering if you've had a chance to fire your amp up yet? How's the fan?

I'm still waiting for mine... :frowning:

Rob...

 

[Bill Fagal]

(Had a nice time at Midwest Audiofest last Friday. Anyone else here go?)

When I called the QSC parts sales rep. and said I only needed one 30A thermistor, they said they'd waive the charge and mail it for free! So this is turning out to be a cheap conversion indeed.

Anyway, I got the 30A thermistor in the mail from QSC last Thursday. Yesterday, I did the conversion. Here's the highlights:

1) Snipped off the two-prong euro plug and Looked at the power cord. Decided it was heavy enough for the higher current draw of 120V so I just put on a nice 90-deg. 15A replacement plug from Lowes.

(MPC200 owners skip to step 5)

2) Pulled the little power PCB off its studs (kind of tricky--you gotta rotate the expanding screws 90 deg. CCW and pinch the ears in--you'll see what I mean if you have one. Be careful not to stress/crack the PCB in all of this).

3) Desoldered the 15A thermistor, removed it, and soldered in the new 30A one.

4) Popped the PCB back on its studs.

5) Switched the 15A fuse for a 20A one and wrote the new value on the fuse sticker with a sharpie.

6) Moved a few friction connectors to different tabs on the PCB (following directions in the JBL conversion fax).

7) Double and triple checked everything (want to keep the smoke in my new amp, don't you know), screwed the cover back on, and wrote "110-120V 15A" on the power label with a sharpie.

I doubt the whole affair took me more than half an hour. Parts cost: Thermistor--FREE! :^) plug, $6.35; fuse, $1.99; roll of solder, $1.99.

Then I lugged the beast over to the nearest power outlet, plugged it in, turned the gain knobs all the way down, and switched it on for a power-up test. I nearly had a heart attack when the red "protection" lights came on! I turned it back off as fast as my finger could move. I hurriedly reviewed the manual and was relieved to be reminded that the amp automatically goes into protection for the first couple seconds of startup. Turned it back on again, and the green lights soon followed the red--whew!

At first, the fan was warbly and wierd sounding, but I let it run for an hour and it smoothed out. I'm going to look into quieter fan options--I understand others have done the research. It's a standard 24V unit.

Sorry, no sound check yet--I didn't have the time to splice it into my system. But I'm not anticipating any probs after the successful power-up.

Bill

PS. Looking at the amp draw specs of the MPC300, I suspect that you could just do the connector, fuse, and plug swaps, leave in the 15A thermistor, and still run OK, especially if you're only pushing an 8-ohm load. At worst, you'll blow the thermistor (maybe spectacularly, so proceed at your own risk).

 

[DustinDT]

How would one get a standard LFE output to connect to the Balanced input headers on this amp?

 

[Bill Fagal]

The inputs aren't XLR plugs like some pro amps, they're on a screw-down barrier strip, so they take bare wire. If you're running an RCA signal wire, just snip off one end, strip a quarter of an inch, run + to + and - to - and skip the neutral, AFAIK.

 

[Bill Fagal]

Oops, Self correction:

From the CX6 manual:

"If you are connecting an unbalanced signal to an input, use the non-inverting (+) input and the ground terminals of the header, and also connect a wire jumper between the inverting (-) input and the ground terminal. The wire jumper will prevent a reduction in gain caused by a floating input."

 

[DustinDT]

Maybe I will understand that more when I actually recieve my amp hehe. All of the pictures of the barrier strip I find are bad quality. Thanks for the help though!

 

[Bill Fagal]

In case anyone is still wondering...

Tested my MPC300 out on some raw drivers--everything seems fine. Just be sure to tie the inverting (-) connector to ground at the input header, or you'll end up with extreme 60Hz hum.

Now for a sub...

 

[WillB]

So do you guys recommend these for Sub woofer amps? Also, how hard was the mod to do? THanks -Will

 

[DustinDT]

To those that have gotten one,
How long did it take your order to arrive from the time you ordered it?
Did you recieve a tracking number?

I ordered on the 13th and have yet to get my amp.

Regards,
Dustin Taylor

 

[Bill Fagal]

Will,

Mod for my MPC300 was easy--MPC200 is even easier. (See previous posts). I have yet to build my sub, so I can't comment on the amp's performance, but I expect it to work just fine.


Dustin,

I got mine maybe 10 days after ordering. No confirmation or tracking # came before delivery.

 

[Rob Formica]

Just thought i'd mention that i've updated my modification information web page at:

http://www3.sympatico.ca/bonaz/JBL/J...-230V-120V.htm

to include some of Bill's experiences with the mod for the unit (thanks Bill ). I will update it at a later time when i get some pictures as well...

Rob

 

[DustinDT]

Ok fellows,
My 200 came in today and I did the listed modifications. I do not have my sub built yet and was wondering if anyone can tell me if I'm on the right track to running this amp in mono parallel mode with both channels driven (one to each voice coil on a dual voice coil sub)the input being a RCA type cable stripped down to bare wire (unbalanced).
The outputs are pretty straight forward but the inputs I'd like some reinforcement on.

The diagram of how I have currently wired is is below



I think its pretty much correct except for I maybe would be able to forgo the jumper from - to ground on channel 2.

Any thoughts?

 

[Bill Fagal]

Hi Dustin,

Congrats on your new amp/mod completion. Pretty easy, wasn't it?

If you've moved the switch on the back to parallel mode, I think you only need to input to one channel--(channel 1, I'm guessing). Try it and see if you're getting signal at both output channels.

The wiring you've illustrated would be necessary if the amp was in stereo mode, but I think the 1ch input/parallel mode is a better idea since it doesn't load your preamp as much.

Though your wiring scheme would work, my manual says to run the center center pin (red) to +, shield (black) to ground, and jumper from ground to -. Your method of running shield to - and jumpering to ground accomplishes the same thing, but if the ground connection rattles loose, you'll get massive 60Hz hum. Wired the way they suggest, if the ground-to-negative jumper comes out, you'll just get a reduction in gain.

Enjoy,

Bill

 

[DustinDT]

It was really easy Bill!
Thanks for all the help.
The MCP200 doesen't have the parallel switch on the back so I was assuming that this wiring scheme would accomplish the same thing externally. I see your point about the jumpers and will probably adjust them accordingly. Once again, thanks for the advice.