AudioCircle
Industry Circles => GR Research => Topic started by: friendswithdave on 5 Nov 2020, 10:59 pm
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Hello All, first time poster, woo hoo!
I just bought a used AV123 MFW-15 subwoofer and noted it appears to have a bad amp. When turned on it produces a pretty loud hum, louder than a ground loop hum I think. I was going to search for this on here to see if others had this issue and knew how to fix it, but I need three posts to get to that, so HELLO! If anyone has a thread they can point me to, I would appreciate it. I actually have an unused powerful amp, but just need a little guidance to connect it to the sub.
Thanks - friendswithdave
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Get ahold of sandbagger here on AC. He maybe able to help with the new MFW-15 amps.
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Replacement amp - https://seatonsound.net/product/mfw-15-mk2-amp/
Possibly helpful for repair tips though not exactly the problem you describe:
https://www.reddit.com/r/audio/comments/4qvoqk/av123_mfw15_humming_fix/
https://www.avsforum.com/threads/advice-on-broken-av123-mfw-15-subwoofers.2545897/
Connecting an external amp - You need to disconnect the existing amp from the subwoofer driver terminals and then connect the external amplifier output (just use one channel if it is a stereo amp) to the driver terminals. If your amplifier is not a subwoofer amplifier you'll lose the ability to adjust output level, crossover point, phase etc.
Here are some external amplifiers designed specifically for subwoofer duty from $99. I know nothing about them:
https://www.outdoorspeakerdepot.com/amplifiers/subwoofer.html
Lastly if you have a local repair shop you could take it to them and see how much it will cost to repair.
Good luck!
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there is a fix that might work, its 4-5 caps as I remember off the top of my head and a bourbon in my hands so....
they are easy to replace.
If that does not work, its dead, do not spend any more time fixing the amp. PERIOD
Mark Seaton does get drop in replacement amps from time to time, he does them in batches though. They are DSP programable for the stock driver or the Turbo driver.
PM me an email or google and you should be able to find the directions
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Thanks everyone for the great info. I may attempt to change out the capacitors. If not (or if that doesn't work), it sounds like an external amp is the next step. I've bought used pro amps before so that may be my next step. I've never changed capacitors or amps before but I did find directions for changing capacitors and changing the amp as a whole should be even easier.
Thanks yall!
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Don't replace one cheap plate amp with another cheap plate amp. Instead, buy this one:
https://www.parts-express.com/dayton-audio-sa230-230w-subwoofer-amplifier--300-813?gclid=CjwKCAiA4o79BRBvEiwAjteoYDUEpgY7I4boxoepoBzVE9cymusFip23T7Yy5bQSuA5jgG_V_LgXXBoCu9AQAvD_BwE
I own an MFW-15 and my amp went bad many years ago. I replaced it with the one linked above. Far superior in sound and much higher build quality.
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I did the same thing and the difference was incredible. the Dayton amp is so much better.
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How easy or difficult it is to replace the stock plate amp with the external Dayton amp?
Additionally, can I split the signal from the processor and share it with the MFW 15 and the Triple OB servo subwoofer?
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How easy or difficult it is to replace the stock plate amp with the external Dayton amp?
Additionally, can I split the signal from the processor and share it with the MFW 15 and the Triple OB servo subwoofer?
Very easy --
Step 1: remove plate amp and disconnect speaker wire from it.
Step 2: unscrew one of the RCA inputs on the plate amp and feed the speaker wire through the hole. Use putty, duct tape, or whatever you have available to seal the hole(s). Reattach plate amp.
Step 3: connect the speaker wire from the driver to the binding posts on the Dayton amp. Connect a subwoofer cable.
Step 4: grab your favorite beverage, turn on some bass heavy music, and dial in your settings.
Yes, you can split the signal from the processor and share it with multiple subs.
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Thanks Early B - is the power from Dayton amp adequate for the MFW15?
I checked the PE website - there is another subwoofer amp rated at 1000watts - any experience or recommendation for this one with MFW 15?
I have two dysfunctional MFW 15 that needs new life.
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Thanks Early B - is the power from Dayton amp adequate for the MFW15?
I checked the PE website - there is another subwoofer amp rated at 1000watts - any experience or recommendation for this one with MFW 15?
I have two dysfunctional MFW 15 that needs new life.
Yeah, you'll have plenty of power. Of course, you can never go wrong with a bigger amp.
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Good to know - what about other features - will the MFW 15 woofer compatible with SA1000?
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Get ahold of sandbagger here on AC. He maybe able to help with the new MFW-15 amps.
I'll second this (if he's still around).
Upgraded my MFW 15 to his "Turbo" version with the external "Seaton" (Modified) Amp.
HIGHLY recommended. If it's still available, DO IT! New Woofer as well. HUGE difference. :thumb:
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Thanks John - just wrote sandbagged a PM.
What woofers are you using? I have the default woofers in my pair.
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Thanks John - just wrote sandbagged a PM.
What woofers are you using? I have the default woofers in my pair.
I don't know if I can find exactly - I know I commented here on AC many years ago when I did the upgrade. Still have photos in the gallery.
(https://www.audiocircle.com/image.php?id=72577)
Quite a difference. Guess which one is which? :green:
(https://www.audiocircle.com/image.php?id=72578)
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New Woofer as well. HUGE difference. :thumb:
Yeah, I replaced the woofer many years ago. Substantial improvement. Try one of these: https://www.parts-express.com/dayton-audio-rss390hf-4-15-reference-hf-subwoofer-4-ohm--295-468
The beauty of the cabinet alone was worth what I paid for the sub, but the amp and driver are low quality. Change those out and you've got a helluva sub.
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My woofers are good for now - but if there is substantial improvements by replacing both the amp and the woofer - I will strongly consider swapping them both.
The SA 1000 amp is out of stock at the moment at PE.
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Hi John - is the upgraded woofer on the left?
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Hi John - is the upgraded woofer on the left?
:thumb:
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I have been having trouble identifying and finding the exact capacitors required. I'm leaning towards replacing the entire amp or selling it as is. Is there a market for these subs with bad amps?
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The answer is YES. Just sold for $200 a day after listing on Facebook Marketplace.
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Don't replace one cheap plate amp with another cheap plate amp. Instead, buy this one:
https://www.parts-express.com/dayton-audio-sa230-230w-subwoofer-amplifier--300-813?gclid=CjwKCAiA4o79BRBvEiwAjteoYDUEpgY7I4boxoepoBzVE9cymusFip23T7Yy5bQSuA5jgG_V_LgXXBoCu9AQAvD_BwE
I own an MFW-15 and my amp went bad many years ago. I replaced it with the one linked above. Far superior in sound and much higher build quality.
I have two mfw15, one is in my basement dead. The other still technically works, but makes weird noise now and the hum fix has already been done. Interested in the extenal alternative mentioned. How long are the speaker wires once you pull them out? Do you just sit the external amp on the mfw or is in in your rack/stand or what?
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I have been having trouble identifying and finding the exact capacitors required. I'm leaning towards replacing the entire amp or selling it as is. Is there a market for these subs with bad amps?
Think I got them from parts express years ago
https://www.reddit.com/r/audio/comments/4qvoqk/av123_mfw15_humming_fix/?utm_medium=android_app&utm_source=share
(https://www.audiocircle.com/image.php?id=217038)
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I have two mfw15, one is in my basement dead. The other still technically works, but makes weird noise now and the hum fix has already been done. Interested in the extenal alternative mentioned. How long are the speaker wires once you pull them out? Do you just sit the external amp on the mfw or is in in your rack/stand or what?
One elegant way to do it is to put a pair of speaker binding posts on the back of the plate amplifier. I would first see if they would fit in the holes where the RCA jacks are. Once you have found a place for them and have mounted them on the plate, connect the subwoofer driver to the speaker binding posts by removing the two wires connecting the driver to the circuit board and then soldering these wires to the speaker binding posts.
Now you have a connection like you do on the back of a pair of speakers. Use your favorite speaker wire of the length required based on where you put the subwoofer amplifiers. I think it looks cleaner to keep the amps in a rack than it does to keep them on top of the subwoofers.
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I have two mfw15, one is in my basement dead. The other still technically works, but makes weird noise now and the hum fix has already been done. Interested in the extenal alternative mentioned. How long are the speaker wires once you pull them out? Do you just sit the external amp on the mfw or is in in your rack/stand or what?
My sub amp sits on top of the MFW. I've also laid the amp on its side to hide behind or on the side of the sub. It doesn't get hot at all. The speaker cables are only 2 - 3 feet long. Once you dial in the sub, there's no need to touch it again. It turns itself on and off.
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My sub amp sits on top of the MFW. I've also laid the amp on its side to hide behind or on the side of the sub. It doesn't get hot at all. The speaker cables are only 2 - 3 feet long. Once you dial in the sub, there's no need to touch it again. It turns itself on and off.
I know you already answered that the sa230 is plenty of power, but what about if I eventually wanted to go back to 2 mfw15? I use to split the signal and use both, but just one huge box is pushing it now with wife approval required. Lol. Guessing I'd need to step up to something like the sa1000 or is the 230 still sufficient?
For anyone else considering the sa230, parts express has a promo code right now for $20 off making it $199 thru 11/18 looks like.
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I know you already answered that the sa230 is plenty of power, but what about if I eventually wanted to go back to 2 mfw15? I use to split the signal and use both, but just one huge box is pushing it now with wife approval required. Lol. Guessing I'd need to step up to something like the sa1000 or is the 230 still sufficient?
You would need an SA230 for each sub.
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You would need an SA230 for each sub.
Back in business with the sa230. Plenty of power like you said.Only issue I had is the speaker cables only seem to be about a foot long. I pulled until it seemed difficult and didn't want to damage anything. So basically just propping it on the back wall for now until I look into the possibility of splicing it. Not sure if that's possible, but I'd like to be able to reach my tv stand. Anyway, thanks for sharing the info here.
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Back in business with the sa230. Plenty of power like you said.Only issue I had is the speaker cables only seem to be about a foot long. I pulled until it seemed difficult and didn't want to damage anything. So basically just propping it on the back wall for now until I look into the possibility of splicing it. Not sure if that's possible, but I'd like to be able to reach my tv stand. Anyway, thanks for sharing the info here.
You can either replace the speaker cable altogether or splice it and make it as long as you need.
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Don't replace one cheap plate amp with another cheap plate amp. Instead, buy this one:
https://www.parts-express.com/dayton-audio-sa230-230w-subwoofer-amplifier--300-813?gclid=CjwKCAiA4o79BRBvEiwAjteoYDUEpgY7I4boxoepoBzVE9cymusFip23T7Yy5bQSuA5jgG_V_LgXXBoCu9AQAvD_BwE
I own an MFW-15 and my amp went bad many years ago. I replaced it with the one linked above. Far superior in sound and much higher build quality.
My MFW-15 finally went and I'm thinking of trying your solution. I've never used an external amp before and just used the LFE. Is there anything a novice like me has to worry about setting this amp up? Thanks for any input you can provide.
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My MFW-15 finally went and I'm thinking of trying your solution. I've never used an external amp before and just used the LFE. Is there anything a novice like me has to worry about setting this amp up? Thanks for any input you can provide.
Very simple. Read Reply #8 in this thread.
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Thanks, I can't believe it's that simple. I just ordered one and look forward to having my boom back this weekend!
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I replaced my busted amp several years ago with Seaton Sound's new replacement amp, with quite an improvement in sound. Seaton loads a custom EQ curve into the amp, based on the particular characteristics of the woofer. I had him load the original woofer profile, since I still have the original woofer (had been waiting for Seaton to finish designing his newer Turbo woofer that would fit my Rosewood cabinet baffle, but he has never finished that project to my knowledge). So, I've just been enjoying the new amp with the original woofer these years. But have always desired to upgrade woofer.
Ok, my question is how much you guys think going with that Dayton upgraded woofer might compromise the sound if I have a Seaton amplifier with EQ based on the original woofer. I know I should just ask Seaton Sound, and I'll likely do so, but thought I'd see what you folks have to say about it.
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Ok, my question is how much you guys think going with that Dayton upgraded woofer might compromise the sound if I have a Seaton amplifier with EQ based on the original woofer. I know I should just ask Seaton Sound, and I'll likely do so, but thought I'd see what you folks have to say about it.
I think you already know the answer. What I will say is that the Dayton woofer will be a substantial upgrade.
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I haven't touched my sub in years, and tried turning it on, and it has the hum. I tried looking for the replacement capacitors, but there are a ton of choices and sizes and brands. Does anyone know the exact specs (including diameter/height) that will work to fix the amp? I tried checking the Seaton Sound for the replacement amp/woofer, but it doesn't look like it's been in stock for a while and I haven't gotten any email response. And since I'm new, I can't send PMs or get profile information to contact members yet. Any help would be great, thanks!
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Hello all,
I know this is a little older, but I just joined the ranks of an AV123 MFW-15 owner. Of course the amp was toast, and I don't feel like repairing a mediocre onboard amp. So, I am going to run it off of a Crown K2 like I do with my current home theater system with great results.
However, I am chime in here because I noticed parts express just came out with a new woofer that might be a good solution for upgrading the driver. It's supposed to work well in a 4 sq.ft. ported enclose. https://www.parts-express.com/Dayton-Audio-RSS390HE-22-15-Reference-Series-High-Excursion-Subwoofer-22-ohm-295-292 I thought I would share this in case someone wants to try it out.
I currently use two 15" RSS390HF-4 15" Reference HF Subwoofers in sealed enclosures for my 2.2 music system, and I think they are decent, especially when considering the cost.
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It does look interesting, and has lower extension in a vented enclosure than the 15" HO reference sub driver. However, it states the ideal volume for a vented enclosure as 4 cuft, but the MFW-15 cabinet is more like 3 cuft. How would that smaller volume impact compatibility?