# MFW15 amp replacment help



## udaman (Mar 16, 2007)

My MFW15 amp out within a few months after the replacing the capacitors. Looking for alternatives to bring it back to life. There are talks of others testing pro amps with the stock driver but didn't find anyone saying they use an external/pro with good results. Any suggestions for a used/new replacement amp, ~$150?


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## theJman (Mar 3, 2012)

You should probably look into the Turbo upgrade kit that Seaton Sound put together. From what I can tell it makes the MFW-15 considerably better.


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## udaman (Mar 16, 2007)

theJman said:


> You should probably look into the Turbo upgrade kit that Seaton Sound put together. From what I can tell it makes the MFW-15 considerably better.


That's one good option but out of my price range.


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## Mike P. (Apr 6, 2007)

Is the driver 4 ohm or 8 ohm?


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## udaman (Mar 16, 2007)

Mike P. said:


> Is the driver 4 ohm or 8 ohm?


it's 4 ohm.


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## J&D (Apr 11, 2008)

I do not think anyone has tried the Dayton SA230 external amp with their stock MFW-15 but it may be an option. Might be a bit underpowered @230W into 4 ohm's but for $199 at Parts Express it may be your only option in this price range.

You would have to extend the driver wires outside the case but that should be a fairly simple process. My V2 amp has high and low level speaker terminals so it should be possible to use a pair of those to make the connections without any drilling. Just disconnect the existing internal connections and wire the driver directly to the terminals. 

Link to amp and specifications - http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-813

My V2 amp is still running fine in mine and I have not had to replace any of the capacitors. You can also head on over to Motor City Custom Audio as there is a chance amps will come up for sale as owners do the turbo upgrade. Good luck in your search, it has been an excellent sub and one that is difficult to get rid of once you get used to that level of performance for the dollar.

JD


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## Mike P. (Apr 6, 2007)

The Bash 300 would be the minimum I'd go with.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-750


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## J&D (Apr 11, 2008)

Agree that the Bash 300 would be a better option but it would not be possible to retrofit the existing MFW enclosure easily to make it fit. I guess you could build a separate box for the plate amp but that would be a bit of a hassle.


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## udaman (Mar 16, 2007)

Mike P. said:


> The Bash 300 would be the minimum I'd go with.
> 
> http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-750





J&D said:


> Agree that the Bash 300 would be a better option but it would not be possible to retrofit the existing MFW enclosure easily to make it fit. I guess you could build a separate box for the plate amp but that would be a bit of a hassle.


The BASH 300 looks good. Yep, this would require a separate box. I'm not much a of diy'er but can probably manage with some pieces of plywood and screws I have in the garage.

Would the 500W version be better, BASH  or DAYTON  ? Not sure if it's too much. The more I look into this the more my budget gets higher. :dontknow:
Here are the specs for the driver from AC forum.

Re 3.04 Ohms fs 15.0 Hz
Le 2.07 mH Mms 235.2 grams
QM 6.62 Mmd 221.6 grams
QE 0.34 Cms 0.476 mm/N
QT 0.32 Rms 3.356 N*sec/m
Xmax 13.02 mm Vas 458.9 liters
Pmax 225 Watts SD 823.7 cm^2
Bl 14.08 Tm VD 1072.3 cm^3
Coil Diameter 2.50 Inches EBP 44.1 
Gap Height 0.375 Inches Magnet Weight 112 ounces
Efficiency 0.44 % Winding Width 1.400 inches
SPL 88.5 dB 1W-1m


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## Mike P. (Apr 6, 2007)

The Bash 500 would give you more headroom but the price is almost $100 more.


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## J&D (Apr 11, 2008)

The only issue you could have with a more powerful amp is the possibility of over driving. Just take it easy on the volume control. 

Since the internal amp is rated at 350W my guess is there is no real advantage to spending the extra $100 for the larger Bash amp. The 300W also fits nicely with your budget. Very interested to hear which way you decide to go and what your results are. Not many have experimented or they have and just not posted much in the way of results. I have an SA1000 that drives a pair of VS18.1's. The problem is I really just do not have the time to take my MFW-15 apart and modify it for testing. I just do not see any reason why any competent outboard amp would not perform well with this sub. Again, just use caution and care when setting it up.


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## fschris (Oct 31, 2009)

I do not think the bash amps are going to fit. 

Sometimes murrell has some to sell. Sometimes you can fin them on ebay.

also, I use a iNUKEDSP from behringer and the DSP1000 can probably power in mono well enough.

I use a iNUKE dsp3000 to power 2 MFW15 clones that I built.


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## udaman (Mar 16, 2007)

fschris said:


> I do not think the bash amps are going to fit.
> 
> Sometimes murrell has some to sell. Sometimes you can fin them on ebay.
> 
> ...


You're right, the bash will not fit. Will be in an external diy wood box. Haven't bought any replacement amp yet til after the xmas bill. 

Interesting that you are use the dsp3000 for the dual MFW15 clone. I would thought the dsp3000 ([email protected]) would be too much for the driver. Even with ds1000 ([email protected] mono) would be way too much. Are you using the original MFW15 driver? If so, how are you liking it so far? thx.


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## baniels (Nov 9, 2006)

What is the volume of the enclosure for the MFW15? And if ported, what are the port details?

The reason he's asking about the Bash 500 is that I have a used one for sale. I'd like to model it up so I can see the impact of the boost/high pass filter. I had modified the resistors according to this table for my old sub. The net result of the changes I made are:

Boost Freq: 20-24 Hz
Filter Fc: 18.7 Hz
Filter Q: 1.3

I'd like to help make sure this will work okay, and if not either guide him or change the values for him. Hoping it will work as it is.


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## fschris (Oct 31, 2009)

baniels said:


> What is the volume of the enclosure for the MFW15? And if ported, what are the port details?
> 
> The reason he's asking about the Bash 500 is that I have a used one for sale. I'd like to model it up so I can see the impact of the boost/high pass filter. I had modified the resistors according to this table for my old sub. The net result of the changes I made are:
> 
> ...


as per nickshitachi:
Port Dimensions 1 1/2" X 44 1/2"

Internal Volume 2.75-2.9 Cubic feet.


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## udaman (Mar 16, 2007)

fschris said:


> as per nickshitachi:
> Port Dimensions 1 1/2" X 44 1/2"
> 
> Internal Volume 2.75-2.9 Cubic feet.


Thanks fschris for the volume info. saving me some time since it will take me a while to google this.


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## udaman (Mar 16, 2007)

baniels said:


> What is the volume of the enclosure for the MFW15? And if ported, what are the port details?
> 
> The reason he's asking about the Bash 500 is that I have a used one for sale. I'd like to model it up so I can see the impact of the boost/high pass filter. I had modified the resistors according to this table for my old sub. The net result of the changes I made are:
> 
> ...


My listening habits are 75%music/25%movies so not sure if that makes any difference in having too much boost at 20-24Hz for music. 

btw: I'm the one contacting you regarding the Bash 500 for sale. thx..


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## fschris (Oct 31, 2009)

this is where you can find murrell... sometimes he used to fix mfw amps. not sure what they are up to,.

http://www.seaton-sound-forum.com/?forum=154357


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## fschris (Oct 31, 2009)

one more thing,,, if you go over to seaton you could always get the mfw 15 turbo upgrade!!

new amp new driver for some heart pounding thunder.


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## udaman (Mar 16, 2007)

fschris said:


> one more thing,,, if you go over to seaton you could always get the mfw 15 turbo upgrade!!
> 
> new amp new driver for some heart pounding thunder.


Turbo upgrade did cross my mind and that would be nice but working with very low budget now. A lot of people who did the upgrade are impress with it so that's a good thing.


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## fschris (Oct 31, 2009)

you only live once... do it! haha or just save up and go for it when you can. the MFW 15 cabinet is solid.


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## baniels (Nov 9, 2006)

This is what I'm showing with the Bash 500. 

The red line represents the default boost/filter in the amp. The green line represents the filter as I have modified it. In either case, you should be fine so long as you are careful with the volume control. 


















Another thing you could do would be to change the values to create a high pass filter with NO boost, as described here.

The blue line represents a 16hz HP with no boost.


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## udaman (Mar 16, 2007)

baniels said:


> This is what I'm showing with the Bash 500.
> 
> The red line represents the default boost/filter in the amp. The green line represents the filter as I have modified it. In either case, you should be fine so long as you are careful with the volume control.
> 
> ...


Thanks for simulating this. Please excuse the newbie question.

When you say 'careful with the volume control' do you mean the one on the plate amp?

Changing the high pass filter to 16Hz with NO boost, what would that yield? Is that a precaution not to over power the driver?

thx..


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## baniels (Nov 9, 2006)

Essentially, yes - to protect the driver. If you see the excursion plots, the red horizontal line represents the xmax of the driver. When you go above that, you risk damaging the driver, so best to keep it under. The high pass with no boost would essentially cut out the lower frequencies that cause over-excursion.

Keep in mind, these sims are with a full 500 watts. You would have to be playing pretty loud to get there. If you keep the gain knob on the sub down a bit, and don't go for concert levels with your main volume control, you will be fine. My previous sub (which I used with this amp), showed massive over-excursion at 20 hz and below with the filter/boost in place. But I only ever bottomed it out once, early on on, watching an extremely bass-heavy movie scene at loud levels. Once I knew the limits, I was able to keep it away from there. 

But for daily use, I had it level matched with my other speakers and didn't worry about it too much. I just didn't crank it way up for really bass heavy scenes. The gain knob on the amp was usually at 70% or so.


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## udaman (Mar 16, 2007)

I don't listen at concert levels so seems like it should be ok. Thanks for the good info.


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## tesseract (Aug 9, 2010)

You can also contact Murrel here: https://simplysoundaudio.com/MFW-15_INFO.html


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## udaman (Mar 16, 2007)

I got the Bash500 amp so it's time to hook the amp to the sub. This is where I need some help.

1. Solder the sub driver cable to binding post
2. Connect the Bash amp speaker cable to the sub binding post. But I don't see the speaker cables on the back of the Bash to connect to the sub.

Now what?


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## baniels (Nov 9, 2006)

There are two tabs labeled speaker + and - on the amp. Look on the board that is facing the camera in your picture of the Bash. 

Did you see the quick connects I included? I sent a couple of each of the two sizes you need.


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## udaman (Mar 16, 2007)

Ahh... now I see it. Thanks for the quick connect with the amp. 

So I attach the speaker cable from the amp speaker (+ - ) to the subwoofer binding post plate? This should be all I need to do?


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## baniels (Nov 9, 2006)

I figured they'd come in handy. 

Looks good. Go for it.


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## udaman (Mar 16, 2007)

Houston we have lift off....:T

Got the amp connected and sub is working again. Have the amp level at 50% for now and level matched with speakers with SPL meter. Still need a box to house the amp.

Thanks to everyone, especially, Ben.


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## baniels (Nov 9, 2006)

You bet, Marcus. I'm glad you got it working. And thanks for buying the amp!


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## elisaw (Jan 18, 2015)

My MFW15 amp also died, and I'm looking to do, essentially, what you did here. Except that being a newbie, and having not done any of this type of "mod" work before, I could use some help!! Especially since you managed yours with such success!!

I have yet to take my unit apart. I was hoping to get guidance before this attempt. Anything someone can DUMB-DOWN for me would be GREAT!

1st, I'm trying to figure out how you managed the soldering of the driver connectors to the binding posts: 
It looks like there are plastic caps. Did you remove them/ strip the wire for the soldering? 

And there looks to be a plate on the binding posts - did you remove that or solder the wires right to the end of the binding post metal, on the exposed side of the plate?

2nd is the question of replacement amp.... I'm guessing with the Bash plate amp you took the connectors, stripped the wire, and then connected directly to the binding post? I'm trying to figure out what you did with those grey and black connectors....

My other concern about the Bash is the need to mod it to get the proper boost. A small soldering job is perhaps in my capabilities, not a large one. 

I found a rack amp unit for ~$310 - OEM brand (??) Model 500. Specs are the following:
Frequency Response: 20 - 300Hz
Crossover Frequency: 40 - 120Hz (Low-pass filter with bypass switch)
Phase Adjustment: 0-180 degrees (Continuously variable)
Amplifier Output Power:
500 watts RMS into 4 ohms, with thermal clipping limiters
250 watts RMS into 8 ohms, with thermal clipping limiters
Distortion: Less than 0.2% at rated power
Audio Inputs: Summing stereo line level (RCA x2) LFE (RCA shared with Left input connector)
Input Impedance: Line-Level - 20k ohms, Unbalanced
Input Power: 120V 60Hz AC
Input Power Connection: IEC 2-wire receptacle with integral fuse holder
Power (Mains) Fuse: 5A 250V GMA style Fast Blow
Power Modes: Auto signal sensing and always on

It also has a 20-35 hz subsonic filter adjustment.

But I cannot find any info or reviews on anyone using it.....

Ok, any help, advice, etc that someone could provide would be appreciated!! My goals are low cost, and somewhat plug-and-play to get my subwoofer working again!


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