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Discussion Starter · #1 ·
Hello all, how is everyone?


Some of you may already know that I purchased an MK Sound SB-1250 250W amplifier and a 4 ohm MK 12" woofer, strange thing is I only receive the deepest of frequencies with NO midbass at all! It's either deep or nothing at all, my system is a Denon AVR-5700 with a fixed 80Hz crossover with my subs crossover in Bypass running M&K LCR 750THX system. This subwoofer lacks midbass and seems slow and tame with no tight bass at all when all my other speakers are working hard! Does the woofer determine operating frequencies or does the amplifier?


Best regards,

Techlord.
 

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+1 on the placement. Perhaps try different placements. Also, try to measure your FR on different location to get a picture of your system.


Al,
 

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Quote:
Originally Posted by CZ Eddie /forum/post/18276204


Impromper room placement can cause severe midbass nulls.

This is no joke. I had a DIY sub as a TV stand and it was horrible placement. I had a huge 15db null from 45-60hz. Thats a wide range i was losing and was completely audible. Now i have a different sub, but in the best place in my room and my response is generally flat +/- 6 db with no eq all the way down till my sub gives up. So placement is a big deal.
 

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Discussion Starter · #5 ·
No, no, no, I have had my older subwoofer in the exact same place as with my newer sub for over ten years! I'm using the same 12" woofer, same sub cabinet but with twice the power. My subwoofer is weak and as in barely outputing much of any bass, midbass. Next...


Regards,

Techlord.
 

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Quote:
Originally Posted by Techlord /forum/post/18276456


No, no, no, I have had my older subwoofer in the exact same place as with my newer sub for over ten years! I'm using the same 12" woofer, same sub cabinet but with twice the power. My subwoofer is weak and as in barely outputing much of any bass, midbass. Next...


Regards,

Techlord.

Next... measure your FR. It doesn't hurt to move it around to see if it's improving. Open up your sub to see if anything wrong? Do an eliminating process like switching back the old amp? Maybe the new amp has problem?


Al,
 

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Discussion Starter · #8 ·

Quote:
Originally Posted by wackii /forum/post/18276463


Next... measure your FR. It doesn't hurt to move it around to see if it's improving. Open up your sub to see if anything wrong? Do an eliminating process like switching back the old amp? Maybe the new amp has problem?


Al,

I originally had the M&K V-1250 125W (12") powered subwoofer, the amplifier died a few months ago. So I went down to Deep Surplus ( Deep Surplus equals M&K gold mine!) and purchase a Cherrywood sub cabinet with the exact same dimensions, next I called up MK Sound and ordered the SB-1250 250W amplifier and new MK 4 ohm woofer. I did try tonight my older M&K 4 ohm woofer and had the same results!


I feel like I'm not getting the full .1 range and on top of that my Denon AVR-5700 THX Ultra receiver has a fixed 80Hz crossover, so there's no way to choose which Low Pass Filter to use!
Right before my V-1250 subwoofer amplifier went bad it also had weak bass.... I am going to try another cable and if that doesn't do it my receiver go's into the shop! It's really that bad! Unless someone knows how to check the subwoofer pre-out for signal strength....


Regards,

Techlord.
 

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Quote:
Originally Posted by Techlord /forum/post/18276494


I originally had the M&K V-1250 125W (12") powered subwoofer, the amplifier died a few months ago. So I went down to Deep Surplus ( Deep Surplus equals M&K gold mine!) and purchase a Cherrywood sub cabinet with the exact same dimensions, next I called up MK Sound and ordered the SB-1250 250W amplifier and new MK 4 ohm woofer. I did try tonight my older M&K 4 ohm woofer and had the same results!


I feel like I'm not getting the full .1 range and on top of that my Denon AVR-5700 THX Ultra receiver has a fixed 80Hz crossover, so there's no way to choose which Low Pass Filter to use!
Right before my V-1250 subwoofer amplifier went bad it also had weak bass.... I am going to try another cable and if that doesn't do it my receiver go's into the shop! It's really that bad! Unless someone knows how to check the subwoofer pre-out for signal strength....


Regards,

Techlord.

what's the lpf set to on the sub amp?
 

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Whats the box displacement? I'm guessing sealed. Do you have the TSPs of the driver? Did you model this at all before building? Just curious.
 

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If you have REW setup you can measure the signal going to the sub. Set it up as a loop through the receiver - soundcard out goes to receiver in, receiver subwoofer out goes to soundcard in - then do a sweep. That will show whether it's the receiver or the sub amp but I suspect the sub amp is at fault here... +1 to the question of what the LPF is set to on the sub amp
 

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Quote:
Originally Posted by Techlord /forum/post/18276101


I only receive the deepest of frequencies with NO midbass at all!

Midbass is considered to be the 80 to 300 Hz range, so if you're not getting that from your sub that's a good thing. If you were getting those frequencies with your old sub you shouldn't have. As for 'tight' bass and 'fast' bass and all those other non-technical euphemisms, they do describe midbass characteristics, and should be heard from the mains, not the sub.
 

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Quote:
Originally Posted by Techlord /forum/post/18276494


I originally had the M&K V-1250 125W (12") powered subwoofer, the amplifier died a few months ago. So I went down to Deep Surplus ( Deep Surplus equals M&K gold mine!) and purchase a Cherrywood sub cabinet with the exact same dimensions, next I called up MK Sound and ordered the SB-1250 250W amplifier and new MK 4 ohm woofer. I did try tonight my older M&K 4 ohm woofer and had the same results!


I feel like I'm not getting the full .1 range and on top of that my Denon AVR-5700 THX Ultra receiver has a fixed 80Hz crossover, so there's no way to choose which Low Pass Filter to use!
Right before my V-1250 subwoofer amplifier went bad it also had weak bass.... I am going to try another cable and if that doesn't do it my receiver go's into the shop! It's really that bad! Unless someone knows how to check the subwoofer pre-out for signal strength....


Regards,

Techlord.

Techlord, make sure your speakers size set as "small" that way your sub can take care of the bass below 80hz. Double check your settings on your receiver.


Al,
 

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Run the wires to a separate amp and you will know if its your amp or your driver.
 

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Discussion Starter · #16 ·
Alright I used my friends receiver today and the SB-1250 subwoofer sounded exactly the same, it was punchy while staying deep. I guess I'm used to the V-1250 125W THX amplifier that is known to not go that deep but is very fast and active while being hard and punchy the way that I like it! I will admit the my older V-1250 125W didn't go deep but blended in with the speed of my 750 speakers midbass, it was that fast! I have two options, (1) somehow find a used working V-1250 125W THX amplifier or (2) buy a smaller sub cabinet, the M&K VX-860 cabinet which is smaller (15" x 15" x 15") than my VX-1250 cabinet. Does anyone think a smaller cabinet would give me that tight hard bass that I'm use to? Also where might I find one of those V-1250 125W amplifier? I'm going to searth this earth for one, I want the bass that my 125W THX amplifier back!


Thanks guys,

Techlord.
 

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Quote:
Originally Posted by Techlord /forum/post/18279728


Alright I used my friends receiver today and the SB-1250 subwoofer sounded exactly the same, it was punchy while staying deep. I guess I'm used to the V-1250 125W THX amplifier that is known to not go that deep but is very fast and active while being hard and punchy the way that I like it! I will admit the my older V-1250 125W didn't go deep but blended in with the speed of my 750 speakers midbass, it was that fast! I have two options, (1) somehow find a used working V-1250 125W THX amplifier or (2) buy a smaller sub cabinet, the M&K VX-860 cabinet which is smaller (15" x 15" x 15") than my VX-1250 cabinet. Does anyone think a smaller cabinet would give me that tight hard bass that I'm use to? Also where might I find one of those V-1250 125W amplifier? I'm going to searth this earth for one, I want the bass that my 125W THX amplifier back!


Thanks guys,

Techlord.

Techlord, so basically you've just double-up the amp power and everything else is the same right? I don't understand why you would lose the "midbass" output unless your new amp is at false. It also sounded like your receiver is fine since you switched receiver and it still sound the same. Why don't you download REW and run some measurements to see what's up?


Al,
 

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Discussion Starter · #18 ·

Quote:
Originally Posted by wackii /forum/post/18283146


Techlord, so basically you've just double-up the amp power and everything else is the same right? I don't understand why you would lose the "midbass" output unless your new amp is at false. It also sounded like your receiver is fine since you switched receiver and it still sound the same. Why don't you download REW and run some measurements to see what's up?


Al,

Download REW, what's that? I am willing to pay for an M&K 125W THX amplifier for the V-1250 and it's weight in gold!! I want middbass!


Everything is not the same, if anything there's less power! I played my Metallica DVD-A disc today like I did 9 years ago and it didn't have hardly any bass whatsoever, but this disc has tons of midbass that my new sub can't produce hench the tame quiet behavior. My M&K V-1250 125W THX subwoofer had TONS of midbass, extremely hard punchy bass that hit hard and fast! I am beginning to think that my Metallica DVD-A disc never really had any bass in it which is why now I am not hearing it, the SB-1250 according to my experience so far has little to NO midbass reproduction whatsoever!


The SB-1250 stays deep no matter the content, if there's midbass in the music disc the SB-1250 will remain silent and tame till such time there's deep low bass on the music disc. Some of my music discs have some really deep bass that seem to bring the SB-1250 to life with thunderous deep bass, if you have a disc with lots of midbass the SB-1250 appears silent and will not have any sound coming from it!



Regards,

Techlord.
 

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Quote:
Originally Posted by Techlord /forum/post/18283259


Download REW, what's that? I am willing to pay for an M&K 125W THX amplifier for the V-1250 and it's weight in gold!! I want middbass!


Everything is not the same, if anything there's less power! I played my Metallica DVD-A disc today like I did 9 years ago and it didn't have hardly any bass whatsoever, but this disc has tons of midbass that my new sub can't produce hench the tame quiet behavior. My M&K V-1250 125W THX subwoofer had TONS of midbass, extremely hard punchy bass that hit hard and fast! I am beginning to think that my Metallica DVD-A disc never really had any bass in it which is why now I am not hearing it, the SB-1250 according to my experience so far has little to NO midbass reproduction whatsoever!


The SB-1250 stays deep no matter the content, if there's midbass in the music disc the SB-1250 will remain silent and tame till such time there's deep low bass on the music disc. Some of my music discs have some really deep bass that seem to bring the SB-1250 to life with thunderous deep bass, if you have a disc with lots of midbass the SB-1250 appears silent and will not have any sound coming from it!



Regards,

Techlord.

REW = Room EQ Wizard. Go here to find out more: REW


Did you attempt to move the sub around to see if it makes a difference? I understand that you want your "midbass" back, but you need to figure what's wrong by trying different things... kinda doing an eliminating process. Maybe the sub is playing fine and that the woofers on your main speakers are dead? Have you try to listen up-close at your mains/woofers? I had a tweeter blown on one of my main speakers before... and like you did not know why it sounds so bad until I listen up-close and figured that the tweeter is blown. I then replaced the new tweeter and my speaker comes alive again.


Al,
 

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Discussion Starter · #20 ·

Quote:
Originally Posted by wackii /forum/post/18283336


REW = Room EQ Wizard. Go here to find out more: REW


Did you attempt to move the sub around to see if it makes a difference? I understand that you want your "midbass" back, but you need to figure what's wrong by trying different things... kinda doing an eliminating process. Maybe the sub is playing fine and that the woofers on your main speakers are dead? Have you try to listen up-close at your mains/woofers? I had a tweeter blown on one of my main speakers before... and like you did not know why it sounds so bad until I listen up-close and figured that the tweeter is blown. I then replaced the new tweeter and my speaker comes alive again.


Al,

I listened to my Metallica DVD-A disc again tonight, I turned up the volume past Reference level and it was loud with deep bass but no midbass. My 750's are the only thing that sound alive with hard fast midbass with tons of high frequencies, my friend came over tonight and said, "where's the sound from the sub"? He thought I disconnected it, none of my friends are impressed by my underperforming subwoofer, they liked the V-1250 with the 125W THX amplifier! I put up a Want It Now ad on eBay for a 125W THX amplifier, I'll pay some serious cash for one or maybe two of them, that's how much I miss my midbass!



Regards,

Techlord.
 
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