Poor bass output

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majorwedgy

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Joined 2006
So definitely isolated the input socket as being an issue. Am amp issue now... There is a high pitch static noise when I touch the heatsink screws and there is a little bit of static on the background, any idea why that would be? Gain improves bass but obviously increases the hiss in the background
 
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Nenola

Member
Joined 2008
Here's my thoughts:

-Too small enclosure, found some suggestions: sealed 7 liters, BR 20 liters tuned to 44hz, BR 30 liters tuned to 39hz.
-Not enough passive radiators, suggestion would be that the passive radiator area would be twice the size of the active driver. I did a similar build with only one Dayton Audio ND91 driver with two 4" passive radiators.
 
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majorwedgy

Member
Joined 2006
Thanks for the help guys, actually think the dsp suggestion is probably the one that is most likely to be cause versus what I aimed to achieve. There is very little movement from the cones and whilst I know the enclosure is not a great size, it doesn't matter what size it is if the air isn't moving. Looking for a cheap headphone dac to see what that does.
 
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majorwedgy

Member
Joined 2006
Worth saying I have a kicker ik500 that has a sound I really like, I was trying to replicate a similar sound profile to that. The kick from the speakers and the passive radiator that has is what this is not replicating. Suspicion is the dsp is the difference, Esp as that is so say 20w a channel
 
M

majorwedgy

Member
Joined 2006
Just an update.
Bought an add on op amp tone board like this one:
NE5532 OP-AMP HIFI Amplifier Volume Tone EQ Control Board DIY Kits Q7W2 192090101153 | eBay

Made a huge difference to the sound and bass - cone movement and sound profile is much improved. Clearly not as deep as it could be (given the limitations of the enclosure volume) but massive improvement.

I do now have a different problem which is a massive amount of interference, going to do investigation as could just be from having some much electronics in the enclosure but suspicion is the add on board has a grounding issue (using a 12v light transformer to power it because requires a 12v AC supply).
 
rabbitz

rabbitz

Member
Joined 2003
I've used that board plus other similar ones and no issues at all and very quiet. However, I used my own components, LM4562 op amps, by-passed pins 4 & 8 and reduced the gain as it was overloading the Class T power amp. I use a 12VAC wall wart and not dual secondaries as well as I've used 7812 and 7912 regs.

I had a thread on this kit.
Ebay NE5532 pre amp tone control gain reduction
 

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rabbitz

rabbitz

Member
Joined 2003
It has been mentioned previously but a 100mm passive radiator is too small for a 130mm woofer.

A lot of these small passive radiators have an Fs that is too low so adding mass just makes it worse as it tunes it lower. To get these tuned higher (60Hz - 80Hz for example) is remove some of the spider. I had to do that with the SB12PAC PR that I teamed with a SB65WBAC.

I have a thread on this.
Passive radiator from old unknown woofer
 
M

majorwedgy

Member
Joined 2006
rabbitz said:
Just a thought. That kit comes with 7815 &7915 regs and you are using a 12VAC supply which is below what is required as you need 15VAC or higher for them to work correctly. You may want to measure pins 4 & 8 to see what you are actually getting.

P05-Mini
Click to expand...

Thanks for this and interesting to know as in the listing it said it needed a 12v AC PSU. Looking at the link you posted it does say the board can be modified to accept 12v so assuming that has happened.
 
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