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Poll Results
 
 How many amps would you PURCHASE at this pricepoint
 1 amp ( I only need a little rumble) 57 60%
 2 amps ( I like to go boom) 29 30%
 3 amps ( I like my neigbors to hear me go boom) 5 5%
 4 amps ( I am a base head and can never get enough) 3 3%
Total votes: 94   Please or register an account to vote.


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Stereodude

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Reply with quote  #61 
I hope they come with a lifetime warranty at that price.
boober

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Reply with quote  #62 
Quote:
Originally Posted by Stereodude
I hope they come with a lifetime warranty at that price.


He's offering a 90 day warranty 
sandbagger

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Reply with quote  #63 
WOW

when I talked to him on the phone last night, he figured he could only get a 30day out of QSC....

Quote:
Originally Posted by boober
Quote:
Originally Posted by Stereodude
I hope they come with a lifetime warranty at that price.


He's offering a 90 day warranty 

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Kevin
Motor City Custom Audio
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Stereodude

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Reply with quote  #64 
Quote:
Originally Posted by sandbagger
WOW

when I talked to him on the phone last night, he figured he could only get a 30day out of QSC....

Now that's confidence in your product!
Reallink

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Reply with quote  #65 
I bet Sand's probably thinking of bumping his potential alternative to at least $300 on the back of this news.  I was expecting $100-$150, NEW V3's, no or 30 day warranty.
Stereodude

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Reply with quote  #66 
Quote:
Originally Posted by Reallink
I bet Sand's probably thinking of bumping his potential alternative to at least $300 on the back of this news.  I was expecting $100-$150, NEW V3's, no or 30 day warranty.

I bet he's not.  I expect more from Kevin than trying to take advantage of people who've already been screwed by VA321.
Murrel

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Reply with quote  #67 
FYI I may have fixed the hum issue on the MFW15 amps. I am going to run it for a couple of days and I will let you all know


Murrel
Timeless_Tech

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Reply with quote  #68 
Are you doing anything special to put some stress on the amp while you let the repair "burn in"?
Murrel

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Reply with quote  #69 
The problem really is in the initial turn on and the onrush into the power supply board. I have watched this board at zero gain and at full gain no real change. 

Yes this amp runs hot mostly the transformer is generating the heat you feel. although the pwr supply board does get warm in a couple of places.


Murrel
Murrel

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Reply with quote  #70 
Timeless,

I am running a sub test tone disc on repeat continually with the gain set at 11 o'clock driving a UFW-12


So far as quiet as you can get.

Murrel 
mak99

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Reply with quote  #71 
Quote:
Originally Posted by Murrel
I am running a sub test tone disc on repeat continually with the gain set at 11 o'clock driving a UFW-12

OK, I'll bite - would there be any difference if it were driving an MFW-15 driver?  I would think not, but this is beyond my knowledge of sub amps and drivers...

Quote:
Originally Posted by Timeless_Tech
Lets see. Which way will the scale tilt when an MFW-15 owner considers whether to purchase from someone who:

A) by all references and appearances is both knowledgeable and trustworthy, although progressing toward a better replacement a bit more slowly than pent-up demand is building?

~~~  OR  ~~~

B) an unknown individual (unless it's one of the former company principals) via nothing but an email address, a so-called MFW-15 amp of unknown origin, performance, and build quality recommended by an untrustworthy individual or his representative?

TT, I'm with you - "A, please!".  I'm patiently waiting for the next round of Turbo kits to be available.  I actually was on the first round of offerings, but unfortunately passed at that time since I had just bought new front speakers...dang it!  In hindsight, I should just have spent the extra $$ and have been done with it - I would've simply dug a bit deeper when the credit card bill came due...
Murrel

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Reply with quote  #72 
I would think that if anything the UFW is harder to drive than the MFW driver as the UFW driver is very stiff excursion wise


Murrel
Mark_Seaton

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Reply with quote  #73 
Quote:
Originally Posted by Murrel
I would think that if anything the UFW is harder to drive than the MFW driver as the UFW driver is very stiff excursion wise

Murrel


The suspension has little to do with how hard a speaker is to drive.  The impedance curve and the spectral content of the signal used matters much more.  From an amplifier's perspective, the UFW-12 is a very easy load to drive, especially between 25-50Hz.  With most of these types of amps, at high output the amps are happier as more of the power gets dissipated across the load and not the output devices.   It would be more useful to test in an MFW-15 box at moderate level as the small chamber is what likely highlighted this weakness in the amps.

There were a few sources of hum which had been noted over time.  One was related to the umbilical up to the control panel and its proximity/orientation to the power transformer (a few ways to reduce this).  Another was a matter of grounding and ground loop issues, and the third was only loosely documented, but seemed to be a progressive problem as the amp died and was likely related to some of the parts with poor tolerance combined with sensitivity to heat. 

I am still pursuing a few promising options from different suppliers to insure we'll have a solution sooner than later.

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Murrel

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Reply with quote  #74 
Well then there you have it I stand corrected.


Thanks Mark


Murrel
Fangel

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Reply with quote  #75 

Quote:
Originally Posted by Mark_Seaton

I am still pursuing a few promising options from different suppliers to insure we'll have a solution sooner than later.


Mark, hopefully you will give us some good news or updates soon as to whether this replacement amp will be feasible or not; otherwise, I'll need to start looking at plan B (whatever that may be ).

 

Fangel

mak99

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Posts: 77
Reply with quote  #76 
Quote:
Originally Posted by Mark_Seaton
Quote:
Originally Posted by Murrel
I would think that if anything the UFW is harder to drive than the MFW driver as the UFW driver is very stiff excursion wise

Murrel


The suspension has little to do with how hard a speaker is to drive.  The impedance curve and the spectral content of the signal used matters much more...

Mark - thanks for the educated response, especially for someone like me that will always ask for help when I'm in unfamiliar territory.

Murrell - No offense, but you might want to do some add'l research (maybe even PM Mark and/or Kevin for their thoughts?) before you respond with what could be interpreted as your "best guess"?  Your response did seem plausible to me, but I guess a well-versed, sounds-reasonable-and-educated response-but-incorrect-response is still incorrect...  Good luck with your endeavors to sell/fix all those amps...
Timeless_Tech

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Posts: 12
Reply with quote  #77 
I'm glad Mark made the distinction between the various types of hum that have been reported. My amps have thus far all died of that 3rd type. Way back in the bad old days of "brute force" non-switching power supplies and discrete components mounted on printed circuit boards, such newfound hum would (at least initially) have you looking for a bad capacitor, maybe a leaking electrolytic letting 60 cycles from the power supply play havoc with the signal before reaching the amplifier.

As for the current hum, if it's induced thermally, the change is not diminished by cooling. It's there immediately the next time the unit has power applied, no matter how long powered completely off (not just between so-called Standby and On).

I've been away from component level of troubleshooting for way too long, but if someone has an interest in following the traces and the software to generate one, I for one would find it interesting to see the schematic(s) of the various boards and how the amps evolved over time. I'm pretty certain schematics would be a valued part of the MFW-15 archives.

Array

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Reply with quote  #78 

You can sign me up for two.  One of the two I have failed recently, and the other has always had a tiny bit of transformer hum.  And I guess the one that still works is on borrowed time now.  So, I'm in for a pair.

nottaway

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Posts: 85
Reply with quote  #79 
Will the new amps be 2-prong or 3-prong?

I don't know what it is about this sub, but I have had to battle ground loop hums with V2 and V3 amps because of the ground plug. 

However the VTF3-MK3 they replaced never hummed a bit in the same location.......

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sandbagger

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Reply with quote  #80 
Quote:
Originally Posted by nottaway
Will the new amps be 2-prong or 3-prong?

I don't know what it is about this sub, but I have had to battle ground loop hums with V2 and V3 amps because of the ground plug. 

However the VTF3-MK3 they replaced never hummed a bit in the same location.......


At this point I cant say with any certainty but.... my guess would be that it will have the standard IEC C14 connector on the back to take the standard 3 prong power cord.

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