Speaker Tech 4 ohm, 8 ohm, 16 ohm

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Lasonic TRC-920

Lasonic TRC-920

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OK Guys, I got a few questions for yeah related to Speakers, Ohm loads and magnet size.

First....If any of you read my General Chat Thread "GPX 990 full tear down and clean" http://www.boomboxery.com/forum/viewtopic.php?f=2&t=5151 I talk about how the speakers in this radio are from a Lasonic TRC-031 and are 16 Ohm.

The radio seems lacking "PUNCH" for it's size,

I don't know what ohm rating the originals were, is there a way to check the radio? Output? Something measurable?

If I swap in some other speakers, say 4 ohm car stereo speakers that are 8 inch but have very large magnets, would I loose even more power? I have a set of KICKERS that have magnets that are easily twice the size. Does it take more power to move speakers with larger magnets?

 
JVC Floyd

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speakers with larger magnets usually have larger voice coils therefore it takes more power to drive the cone ,if you are going to use a car audio speaker rated at 4ohms it might make the amp run hot or even burn out the ic chips unless the amp is rated to be stable into 4ohms ,speakers with 16 or 8 ohms draw less power from the amp @ 8 ohms you draw 1/2 the power that you draw @4 ohms 16 ohm speakers draw 2/3 less power from the amp them at @4 ohms ,also speaker sensitivity plays a key part the higher the number the more efficient the speaker is example a sensitivity rating of 100db's 1 watt at 1 meter will be 50% more efficient than a rating of 50 db's @1 watt of power from 1 meter away.
 
MasterBlaster84

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All things being equal lower resistance (4 ohms vs 16 ohms) allows the amp to output more power which is why an amp rated for 8 ohms but not 4 will get hot, basically there isn't enough resistance against the amp to keep it within it's designed parameters. Floyd is correct that this will sooner or later burn the amp up so you really need to know what the rating was on the original speakers or find the specs for the amp which may be tougher. The best thing you can do with replacement speakers is make sure they are efficient as Floyd says, you'll want to keep the sensitivity rating high for decent volume. Speaker designs are all about compromises, no one speaker does it all well so you may have to experiment.
 
JVC Floyd

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one way to test the impedence of a speaker is to use a multi meter just set the meter to read ohms and place the probes onto the speaker terminals.
 
Fatdog

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I would guess that the original speakers are 3.2 ohms. Going with a 4 ohm woofer won't hurt the amp too much. Magnet size really only matters if you are short on space or if the plastic posts can't handle the added weight.

Be sure and get woofers with the highest sensitivity rating - at least 91db or higher.
 
monchito

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and really most of the boxes had 4 ohm speakers or basicly 3.2 or 6 ohms and there are a few with 8 ohms more than likely that box came with 3.2 or 4 ohms,, 16 ohms is really too much for a boombox to produce some sound,, those lasonic trc- 931 speakers can work well but it need a good amp to drive them max on those speaker i belive were 35watts :yes: :yes: :yes: btw the lasonic speakers are in fact 4 0hms but rated from 16-35 watts :yes: :yes: :yes:
 
Superduper

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JVC Floyd said:
speakers with larger magnets usually have larger voice coils therefore it takes more power to drive the cone ,if you are going to use a car audio speaker rated at 4ohms it might make the amp run hot or even burn out the ic chips unless the amp is rated to be stable into 4ohms ,speakers with 16 or 8 ohms draw less power from the amp @ 8 ohms you draw 1/2 the power that you draw @4 ohms 16 ohm speakers draw 2/3 less power from the amp them at @4 ohms ,also speaker sensitivity plays a key part the higher the number the more efficient the speaker is example a sensitivity rating of 100db's 1 watt at 1 meter will be 50% more efficient than a rating of 50 db's @1 watt of power from 1 meter away.
Click to expand...
Floyd. db (decibels) is a logarithmic scale and not a linear scale so a speaker with a 100db SPL sensitivity rating will probably be more like 10,000 times more efficient than one with a 50db SPL sensitivity rating (not calculated, just arbitrarily tossing a large number out there to make the point, that it's not a linear relationship).

DB and power: When talking about power, 3dB represents a ratio of two to one or a doubling of power.
•Thus, a gain of 10dB would represent a ratio of ten to one for power - so 10 dB be 10 times the power
•A 40dB power gain would be 10,000 times the power.

DB and SPL: The term “SPL” stands for sound pressure level. SPL measures are taken with respect to the minimum threshold for human hearing. A 20 dB difference in SPL represents a ratio of ten-to-one in sound pressure.
•Thus, a 40dB SPL would be a sound pressure level that is 100 times greater than the sound pressure level of the quietest sound that normal human hearing can detect.

DB and Volume: Interestingly, our perception of loudness is not the same as sound pressure level. Although the actual formulae
is somewhat complex, as a rough rule of thumb, an increase of 10db SPL is perceived to be approximately twice as loud.
•Thus a 20 Db gain would seem to be about 4 times as loud.
•And a 40 Db gain would seem to be about 16 times as loud.
 
JVC Floyd

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Superduper said:
JVC Floyd said:
speakers with larger magnets usually have larger voice coils therefore it takes more power to drive the cone ,if you are going to use a car audio speaker rated at 4ohms it might make the amp run hot or even burn out the ic chips unless the amp is rated to be stable into 4ohms ,speakers with 16 or 8 ohms draw less power from the amp @ 8 ohms you draw 1/2 the power that you draw @4 ohms 16 ohm speakers draw 2/3 less power from the amp them at @4 ohms ,also speaker sensitivity plays a key part the higher the number the more efficient the speaker is example a sensitivity rating of 100db's 1 watt at 1 meter will be 50% more efficient than a rating of 50 db's @1 watt of power from 1 meter away.
Click to expand...
Floyd. db (decibels) is a logarithmic scale and not a linear scale so a speaker with a 100db SPL sensitivity rating will probably be more like 10,000 times more efficient than one with a 50db SPL sensitivity rating (not calculated, just arbitrarily tossing a large number out there to make the point, that it's not a linear relationship).

DB and power: When talking about power, 3dB represents a ratio of two to one or a doubling of power.
•Thus, a gain of 10dB would represent a ratio of ten to one for power - so 10 dB be 10 times the power
•A 40dB power gain would be 10,000 times the power.

DB and SPL: The term “SPL” stands for sound pressure level. SPL measures are taken with respect to the minimum threshold for human hearing. A 20 dB difference in SPL represents a ratio of ten-to-one in sound pressure.
•Thus, a 40dB SPL would be a sound pressure level that is 100 times greater than the sound pressure level of the quietest sound that normal human hearing can detect.

DB and Volume: Interestingly, our perception of loudness is not the same as sound pressure level. Although the actual formulae
is somewhat complex, as a rough rule of thumb, an increase of 10db SPL is perceived to be approximately twice as loud.
•Thus a 20 Db gain would seem to be about 4 times as loud.
•And a 40 Db gain would seem to be about 16 times as loud.
Click to expand...
:agree: i was trying to say that without saying all of that .
 
MasterBlaster84

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JVC Floyd said:
Superduper said:
JVC Floyd said:
speakers with larger magnets usually have larger voice coils therefore it takes more power to drive the cone ,if you are going to use a car audio speaker rated at 4ohms it might make the amp run hot or even burn out the ic chips unless the amp is rated to be stable into 4ohms ,speakers with 16 or 8 ohms draw less power from the amp @ 8 ohms you draw 1/2 the power that you draw @4 ohms 16 ohm speakers draw 2/3 less power from the amp them at @4 ohms ,also speaker sensitivity plays a key part the higher the number the more efficient the speaker is example a sensitivity rating of 100db's 1 watt at 1 meter will be 50% more efficient than a rating of 50 db's @1 watt of power from 1 meter away.
Click to expand...
Floyd. db (decibels) is a logarithmic scale and not a linear scale so a speaker with a 100db SPL sensitivity rating will probably be more like 10,000 times more efficient than one with a 50db SPL sensitivity rating (not calculated, just arbitrarily tossing a large number out there to make the point, that it's not a linear relationship).

DB and power: When talking about power, 3dB represents a ratio of two to one or a doubling of power.
•Thus, a gain of 10dB would represent a ratio of ten to one for power - so 10 dB be 10 times the power
•A 40dB power gain would be 10,000 times the power.

DB and SPL: The term “SPL” stands for sound pressure level. SPL measures are taken with respect to the minimum threshold for human hearing. A 20 dB difference in SPL represents a ratio of ten-to-one in sound pressure.
•Thus, a 40dB SPL would be a sound pressure level that is 100 times greater than the sound pressure level of the quietest sound that normal human hearing can detect.

DB and Volume: Interestingly, our perception of loudness is not the same as sound pressure level. Although the actual formulae
is somewhat complex, as a rough rule of thumb, an increase of 10db SPL is perceived to be approximately twice as loud.
•Thus a 20 Db gain would seem to be about 4 times as loud.
•And a 40 Db gain would seem to be about 16 times as loud.
Click to expand...
:agree: i was trying to say that without saying all of that .
Click to expand...
Trying to talk tech without talking tech is a skill. :hmmm: :-D
 
MasterBlaster84

MasterBlaster84

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Superduper said:
MasterBlaster84 said:
Trying to talk tech without talking tech is a skill. :hmmm: :-D
Click to expand...
That is a concept and skill that us logical guys can't comprehend. Just like bones (TV series) can't comprehend the complex illogical happenings of social interactions.
Click to expand...

:lol: Yep I lose people on occasion even when I'm trying to translate into first level lingo.
 
Lasonic TRC-920

Lasonic TRC-920

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WOW....Thank you guys....You may have lost me there....as I am not as technically inclined. How ever, I am going to open up the box right now and check the speaker info to see if I may have read that incorrectly. Maybe misreading 16w thinking it was 16 ohms.
 
monchito

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i will be honest that box is basicly all she is going to give speakers are ok bass is going to be a bit shy but it will still be ok i do not think its the speakers really :-) :-)
 
gld1307

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I did ready that a high SPL rating is less important with bass a frequencies. In any case I think it may be useful to look at the freqency response graphs for the speakers you want, with the information the guys here have given you in mind.

Best of luck
 
Lasonic TRC-920

Lasonic TRC-920

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monchito said:
i will be honest that box is basicly all she is going to give speakers are ok bass is going to be a bit shy but it will still be ok i do not think its the speakers really :-) :-)
Click to expand...
I think your right monchito, As much as this is a beautiful and large box, I don't think it's a big performer. It's a cool radio, but it's not a really loud box.

With that all said, I'm still happy to have it in the collection. It's clean and complete, I'd still like to get the cassette working and will keep it. Plus the price was right, so no complaints at all.

NEXT!
 
monchito

monchito

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i have boxes like that and to me they are all good in there ways the gpx you have is a nice example of a good looking box ,, not that many have them so consider that as a good buy and worth having in any collection :yes: :yes: :yes: :thumbsup: :thumbsup: :thumbsup:
 
Lasonic TRC-920

Lasonic TRC-920

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monchito said:
i have boxes like that and to me they are all good in there ways the gpx you have is a nice example of a good looking box ,, not that many have them so consider that as a good buy and worth having in any collection :yes: :yes: :yes: :thumbsup: :thumbsup: :thumbsup:
Click to expand...
I totally agree. I have other boxes that go LOUD if I need that. Believe it or not, this GPX really shines in clarity at low volumes and it has virtually no hiss. So in a mellow environment it is fine. Plus it looks great next to the GF-777 :-D :-D

The next goal for this box is to get the tape deck working. Chris (TRC-918) thinks he might have the buttons for it, if not, I'm going to mold them myself. I'm also looking into chrome plastic plating. I might send in all my knobs to one place and have them all done. So if I do and I make new buttons, no one will ever know!

I still think it's a great looking box!

 
MasterBlaster84

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gld1307 said:
I did ready that a high SPL rating is less important with bass a frequencies. In any case I think it may be useful to look at the freqency response graphs for the speakers you want, with the information the guys here have given you in mind.

Best of luck
Click to expand...
Keep in mind boomboxes use drivers that aren't really Bass speakers in the true sense, they cover mainly the mid bass through midrange or at the deepest 60 to 80 hz up to about 4,000 in two way systems. In this regard these drivers generate the overwhelming amount of sound that a boombox produces and do so typically only on several watts of power so yes in these cases efficiency is pretty important. :yes:
 
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