| jbop |
I'm new so, Hi everyone.
Im using a pair of Seas P25REXDD as drivers in my subs, and I recently made an effort to improve tightness by installing a longer port in my old cabinets. What has happened is that I got an improvement in tightness, but at the same time I had what appears to be a peak somwhere in the lower regions.
I'm wondering if this peak comes from the box being more of a closed cabinet as I increased the port length and that the peak could be the resonance point the setup would have if I removed the port.
Does anyone have a suggestion as to how I should proceed?
I wish to keep the tightness and get rid of the peak in an easy and cheap way. |
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| GM |
Greets!
Sounds like the pipe's long enough for its 1/2 WL harmonics to become audible, which will require some form of damping, lowering output a bit in the process. It may be better to revert to the original vent length and damp it as required to 'kill two birds with one stone'.
GM |
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| Cal Weldon |
| While I certainly can't compare with GM's knowledge, when the bass sounds loose or chuffey, I say "put a sock in it" I think he's correct in suggesting reverting to the original port and damping it. |
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| GM |
| LOL! That was my first response, but decided it was too flippant! |
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| sreten |
Hi,
Try reverting to the original port and lining it (not blocking it) with foam.
Usually need an oblong around 8mm / 3/8" thick x 3(diam) x length.
:)sreten. |
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| jbop |
Okay, so what seems to be the general opinion is that I should revert to my old pipe, and increase the amount of damping I use.
Hmm....
I was thinking more along the line of putting a notch filter on it to dampen the peak. I seem to get a good frequency response except for this peak wich colours the bass range. |
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| tinitus |
If I am not mistaken your driver has a Qts of 0.44, which in BR would need a BIG box, to avoid peaking ... and with xo above 40hz, and additional room gain ..... who knows what might happen
Question is ... how low can you push a driver like this, without loss of control |
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| jbop |
The more I reengage in this project the more I remember how I thought when the subs came to be in the first place. The box size is around 60l wich is optimal for this driver in a closed box application, but then after a while I added a vent just to see what happened.
Without the extra amplifier, and the added output level the problems I experience now weren't that noticeable. They are now however..... Ugh.
Perhaps I should plan for a new cabinet. The ones I have now are ugly anyway.( Extremely ugly according to some.)
Are the Seas drivers I have worth the effort, anyone? |
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| tinitus |
Have you experimented enough with level and xo settings ?
What kind of subamps do you have ?
Which music do you play mostly, and at which level ?
What are your expectations ?
What are your main speakers and amp ?
Do you play analogue records or only CDs ? |
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| GM |
Greets!
Don't have the specs for the P25REXDD, only the P25REX, but assuming it's fairly close it's suitable for either a MLTL or pipe horn sub if you can tolerate the size.
GM |
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| jbop |
I have a tunable active low pass filter and I pretty much always adjust the level between records prior to listening.
The subs are powered by a (modified) Musical Fidelity P140, wich is as those of you who know it the last amp anyone would use to power a sub with. However, with a PSU that has been up-tweaked silly the current handling is excellent.
I play everything except for Swedish 'dansband' at pretty much every available level and I also run this rig as front speakers for the surround setup.
Well, there's nothing called 'good enough'. I assume that everyone here agrees with that. What I aim for is a rig that doesn't make me feel like adjusting the output level of the bass all the time.
Main speakers are dual 5" Mid/Bass drivers in a 35l vented cabinet and a Vifa ring radiatior tweeter. A Yamaha AST-A10 powers the mid range, and a Musical Fidelity A1 powers the high frequencies.
For practical reasons it's mostly CD, but I prefer real records. |
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| jbop |
| MLTL? I'm not familiar with this abbreviation. Remember I'm new. |
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| GM |
Greets!
MLTL = mass loaded transmission line. Basically, it's any high aspect ratio speaker with the driver near/at one end and the vent at the other. Do a search, lots of info available here, and for the physics of them: www.quarter-wave.com.
GM |
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| tinitus |
If GM will simulate it for you, it might be your ticket to fantastic bass
Key issue could be less cone movement, which would lead to better bass controll
GM is the expert on these matters ;) |
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| bjorno |
jbop,
Or very close:
1(4) |
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