modify speaker frequency

tald

Member
2005-08-11 9:33 pm
It is maybe a stupid question but i have only basic crossover knowledge.
I have a speaker that goes down to 30hz and produce too heavy bass.
Is it possible to change only the extreme low to 50hz without any information
about the speaker parts ? (maybe by adding a resistor only to the midbass unit).
 
Hi, a speaker ( system) operates in a larger system ( source-amplifier-speaker-cables-room-auditioner).
The easiest way is to operate ( again!) at line level, by introducing the HP ( high-pass) before the amplifier.
Search for PLLXO, just simple formulas for calculating a C-R network correctly.
Probably you'll eventually end in changing just the input capacitor of the amplifier ( say, from 2.2 uF to 100 nf).
 

johnego

Member
2017-12-17 3:13 am
I don't know if "too heavy bass" is an expression everyone should understand. Is it really related to 30Hz? No possibility that it is related to something else far above that frequency? LF extension is determined by the box volume and port, so try sealing the port first then see how low the frequency you get (if still too low, which is unlikely, reduce the box volume by throwing shoes inside the box). It can be done through the electronics too (HPF). But honestly, I don't know what's going on :)
 

YSDR

Member
2013-11-24 8:13 pm
As was mentioned, if you hear the bass as too heavy, then the problem usually is around 50Hz and above.
The best starting point would be some measurement with a calibrated mic and an adequate software. Or you just try moving the speakers away from the wall/corner.
For in-room response correction, you can try a DSP solution too.
 
Last edited:
Hi TALD

1. Unlikely that a published response going down to 30 is the source of your 'too much bass' problem. Little common music has much down there - and if there is it will not be so powerful - unless you are playing home cinema effects.

2. More likely is the in-room response of your speakers and the 'too much bass' is actually a 'boom' of quite a bit higher frequency than 30Hz

3. Obtain or borrow an amp with tone controls, and see if the bass control can make a difference

4. Pull speakers away from the wall or corner - corners are bad for bass boom.

5. Perhaps you have speakers that are down close to the floor? - (a friend of mine has standmount speakers on the floor - they sound terrible but he likes it). If so - get 'em up! Floor coupled speakers can boom.

5a. Have you got a Wood bouncy floor? - try isolating the speakers from it - springy feet or Townshend platform (expensive!)

6. If you have digital sources (Roon in use? or other) they may have DSP options that you can use to tune the response.

7. Room response can be altered with change of furnishings or using bass traps in corners perhaps.

BUT in all of this you will notice that messing with the speaker itself is not the first point of call - you can possibly mess with port blocking but not many speakers are designed to run well with a blocked port as an option. I have a personal preference for sealed speakers - they are 'easier' to integrate into a room.
 

tald

Member
2005-08-11 9:33 pm
Hi guys. tnx all for your answers.
Lets forget about all i wrote and turn this into theoretical question.
Is it possible to change extreme low frequency of a a speaker
from 30hz to 50hz (numbers only for example) without any info
about the speaker units, cub, crossover ?
 

adason

Member
Paid Member
2004-11-10 8:31 pm
Maryland
Hi guys. tnx all for your answers.
Lets forget about all i wrote and turn this into theoretical question.
Is it possible to change extreme low frequency of a a speaker
from 30hz to 50hz (numbers only for example) without any info
about the speaker units, cub, crossover ?

If you are trying to limit low fr response of the speaker, you have many options how to do that. You can do it passive, inserting capacitor between the amplifier and the speaker is one way. This will be large capacitor, so I suggest bipolar. Bipolars for crossovers are cheap, sound ok, and can by paralleled with mp cap for those who believe can hear the difference. For 4 ohm speaker, cap is ~ 800uF, for 8 ohm speaker ~ 400uF. That is microfarad.

More elegant way to do it is in line level, by inserting high pass filter. Which is basically capacitor again in signal pass, followed by the buffer with certain resistor on the input. Plenty of such circuits around. You can make it passive, but passive followed by buffer is safer. Off course there is plenty of active circuits published, you just need to search. I made many active crossovers, typically at ~150Hz, which allows me to use biamplification.

Other option is you insert equalizer between your signal and amplifier, and you use lowest fr pot to tailor the sound to your liking. Equalizer should be 15 band, or better 31 band, to work well for this purpose. Equalizer can be old fashioned analog with multiple opamps, or digital. I use ultra curve Behringer.

Plenty of choices, but you provide little information really. Ideally, you measure in room response, as to know exactly what is going on. Some people call it bass, but it may be midbass. Who knows. Most bookshelf speakers do not really produce clean bass anyway.