Adding speakers, what happens?

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Lasonic TRC-920

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I know that if you drop the ohms to low on an amp it will overload it, but what happens if you add a tweeter, or even a piezo tweeter to a system?

If you have a stereo that only has woofers and no tweeters and you add tweeters, will it FRY?

What happens when you have a 2 speaker system (woofer/tweeter per channel) and you add a second tweeter, will it FRY?
 

jimmyjimmy19702010

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Hi Chris,

Adding a speaker/speakers will decrease the impedence that the amp will see. It depends on the specs of the amp and the ohm ratings of the existing and new (to be added) speakers.

As an example, my DIY V3.0 box had the same sized mids and woofers. Each speaker was rated at 12 ohms. When they were connected, the amp 'saw' 6 ohms.

Do you have the details of your setup?

James... :-)View attachment 27236
 

Lasonic TRC-920

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kennerithmcguire said:
Depends on the amplifier and the lowest impedance it can handle. The amp doesn't see a difference between a woofer and a tweeter.

I would use a proper crossover to keep the impedance at 4-6-8 ohms. The other option is to run the speakers in series or series parallel.

http://www.prestonelectronics.com/audio/Impedance.htm

Hope this helps....
jimmyjimmy19702010 said:
Hi Chris,

Adding a speaker/speakers will decrease the impedence that the amp will see. It depends on the specs of the amp and the ohm ratings of the existing and new (to be added) speakers.

As an example, my DIY V3.0 box had the same sized mids and woofers. Each speaker was rated at 12 ohms. When they were connected, the amp 'saw' 6 ohms.

Do you have the details of your setup?

James... :-)
image.png
Thanks guys,

I don't have the amp specs. Basically I was thinking about the Wheely Dynasty HT-959.

It's a 2 speaker setup, 10 inch woofer, tweeter. But it needs more. It needs a mid in there to get the volume up.
 

jimmyjimmy19702010

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Speakers connected in parallel will result in a lowering of the impedance. Connecting them in series will result in a raising of impedance.

So two 4 ohm speakers in parallel will have the amp seeing 2 ohms. Two 4 ohm speakers in series will have the amp see 8 ohms. Raising the ohms won't hurt the amp but it will lower the output.

I'd try maybe connecting a 6 ohm mid speaker in parallel and see how you go. Choosing a speaker with a suitable sensitivity will be key.

James... :-)
 

Lasonic TRC-920

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jimmyjimmy19702010 said:
Speakers connected in parallel will result in a lowering of the impedance. Connecting them in series will result in a raising of impedance.

So two 4 ohm speakers in parallel will have the amp seeing 2 ohms. Two 4 ohm speakers in series will have the amp see 8 ohms. Raising the ohms won't hurt the amp but it will lower the output.

I'd try maybe connecting a 6 ohm mid speaker in parallel and see how you go. Choosing a speaker with a suitable sensitivity will be key.

James... :-)
What are your thoughts on this?
http://www.parts-express.com/tang-band-w2-1803s-2-neodymium-poly-full-range-driver--264-885
 

jimmyjimmy19702010

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Lasonic TRC-920 said:
Very low sensitivity (82dB)View attachment 27256

Due to the fact that the existing speakers are probably high sensitivity, I don't think these new speakers would play loud enough to solve your weak mids situation.

Aim for speakers which have a sensitivity of around 88 dB or better. Smaller speakers with high sensitivity are rarer than larger speakers but they are around.
 

Superduper

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Chris,

You would think that ohms and it's relative measurement/calculation would be rather simple but impedance is not so simple as it would seem. The reason is that while ohms of resistance in, say a resistor, remains consistent in a circuit, the ohms of a speaker resistance (impedance) varies with frequency. In a single audio program, there are highs, lows, mids, and every frequency in between and during operation, the ohms that the amplifier will actually see varies from very low (maybe sub-2 ohms) to very high ohms.

When you add a tweeter into a circuit, you are doing so, presumably through a high-pass filter cap. Therefore, only the very high notes are passed onto the tweeter. As the most demanding and strenuous frequencies are in the low z's, and since those frequencies are filtered out and not passed onto the tweeter, therefore, the amp only really sees a tweeter when it is passing high notes. The rest of the time, it's like it's not even there. What's this all mean? Well, it means that you simply can't calculate the impedance of a speaker circuit like this and say that with the addition of this or that driver, you will get "x" impedance. In general, you can safely add a tweeter into a circuit through a filter cap and the extra load to the amplifier is negligible.

Not so if you add other "full-range" drivers that get the full signal however since it will then mean that the entire signal is being shared all the time, and not just on selected notes or hz. Now since your speakers are already 4-ohm drivers, it is inadvisable to connect another driver in parallel since that could indeed halve the imedance (if 4-ohms). If you connect a 6 or 8 ohm driver in parallel, then the impedance will be between 2 and 4 ohms but higher than 2. There is a formula to calculate but unless you want me to, I won't bother because I don't recommend it. Now you can install them in series and that would be perfectly OK for your amp, but I also do not recommend it.

Here's the reason why.... Unless you are using matched drivers, running them in series or parallel is unwise because one or the other will almost surely have different specs and characteristics. That does not mean that they will complement each other. Rather, you will find that the louder one will basically drown out the other one. If you don't believe me, put 2 boomboxes next to each other and turn one up to a certain loudness. Then turn up the other one to a significantly more powerful volume setting. I bet the only thing you are going to end up hearing is the louder boombox. The softer one will be invisible. Remember that expression, if you fell a tree in the forest, and nobody is around to hear, does it make a sound? Yeah, it's like that except that in this case, it truly is that it's making noise but you can't hear it. All right, to satisfy those who will say maybe the specs aren't that far off? Let's just say that it doesn't take much mismatch to make one driver disappear. Maybe not entirely, but enough to beg the question why bother with the extra driver if it's just going along for the ride with nothing to add?

Here is where I think you can do something that will improve the sound overall and accomplish what you desire... go ahead and add another driver, prefereably a high/midrange and not a full range driver (which will do a crap job of competing with the 10 incher). Install a 3-way crossover. When you do this and if the crossover is properly designed for the number of drivers you plan to use, then the entire impedance in the array remains unchanged regardless of how many drivers you have. And even better... the lows go to the woofer, the mids go to the midrange, and the highs go to the tweeter. Each driver performing at it's optimum environment. Basically the crossover divies up the signals based on the Hz and sends them off to the proper driver. Even though the woofer is being fed the full signal (in a system without a crossover), the highs are wasted since it isn't capable of reproducing it, or at least not capable of doing it well. The only reason you don't see an inductor in series (to filter out the highs) is because #1 it adds cost and #2, the highs don't hurt the woof like the lows will hurt a tweeter. However, it's wasted energy since it gets the same signal that the tweeter is getting.

Hope this helps you to understand it a bit better.
 

Lasonic TRC-920

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I know we are talking about less STICKIES, but I think this should be one.

Thank you Norm for this explanation

What I am now looking for...are nice set of mids, a nice set of tweeters and a nice set of cross overs. Of course I will be using the factory Dynasty woofers.

So the next question is...

4 ohm mids and 4 ohm tweeters?
With High Sensitivity 88 db or better.

Crossover question...
When setting up a crossover, do you want the frequency levels to overlap from woofer to mid and mid to high? Or do you want a cold cut off at frequency "X"

Also...
Does the woofer still get FULL RANGE?
 

jimmyjimmy19702010

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So is the problem that the box doesn't seem to play loud enough?
Chances are that amp is probably on the weedy side. Maybe splice in a new amp !?

Your existing woofers are probably receiving a full range signal with a simple cap on the tweeter. As Norm was saying, sending highs to the woofer is a waste of power as the woofers ability to reproduce highs is severely limited.

If you go with an off the shelf 3 way passive crossover, the driver will only be fed lows which is a good thing.

You could salvage a 3 way crossover from a low end home HiFi speaker that utilises 4 or 6 ohm speakers. Use the mids and tweeters from the host cabinets and your existing dynasty drivers.

That way, you know the crossover is matched to the mid and tweeter speakers.
 

Superduper

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Ok, so just in case I wasn't clear before. If you were to parallel or series connect multiple speakers together, you can generally rely on ohms law to do the calculation. But speakers aren't usually connected in that way. If you parallel tweeters to woofers without some kind of filter, they would blow. On midranges, you generally don't want the lows or the highs since they their forte is mid z's. Too low and they'll fart, and too high and they simply won't be effective. And while low z drivers aren't hurt by mid or high signals, that's not their specialty. So on cheap devices like boomboxes, to keep parts count (and manufacturing costs) down, woofs generally get the full signal. The tweets get a high-pass filter that might chop off (roll off, actually) signals below 6, 8, 10khz... some level depending upon the value of the capacitor and the tweeter impedance. What all this means is that unlike if you were to simply inject a straight 1khz signal and measure impedance, a dynamic signal simiply can't be easily measured using ohms law since the tweeter isn't really even a factor if/until the signal includes highs that is passed through. And what do you listen to anyway? 10 people and you get 10 answers so the effect on the amplifier is.... it depends.

=====================

To your question, you can buy pre-made crossovers or you can fabricate your own using software that you can buy (parts express sells the software). The software calculates the values of the crossover parts to use as well as the circuit diagram based upon the specs of the drivers you will be using. Of course if you buy your own tweets and midrange, those specs are available but the woofer specs will be an unknown. Although not 100% perfectly tailored to your own setup, premade crossovers generally work well enough and should be an improvement over no-crossover. Off the shelf crossovers are usually designed for 4 or 8 ohm systems. You can mix other impedance drivers into the mix instead but the crossover points will change and system might sound "off".

As for cutoff, there is always some amount of overlap or soft roll-off. You never want a hard cut off, it will most likely be audible. Simplest thing you can do is just get a premade crossover and tinker from there. Also, you may find that the tweets or mids are too bright. This frequently occurs because high efficiency tweeters are easier to find than high efficiency woofers and midranges. Also, the ears are more sensitive to midrange (a 50 hz signal even at high current isn't likely to cause too much distress but a 1khz signal at moderate to high signal levels will be piercingly loud and unbearable). To combat this, if your drivers aren't matched well in sensitivity, you may need to series a resistor inline with either the midrange or tweeters to attenuate them a bit. Or you can buy what they call "L Pads".

Additionally, the woofers can be operated with full range signal. But your crossover will likely include inductors that will attenuate the higher frequency if you use it the way it's intended. If you buy off the shelf crossovers, you will find the following connections: 1-input, 2-woofer, 3-midrange, 4-tweeter. Woofers usually get a low pass signal, tweeters a high pass signal and midranges get a band-pass signal. The only way I see you getting full range to the woofer is if you decide not to use the connections at the crossover intended for the woofers. Let the woofs do the job they are designed to do and let the other drivers do their respective part. Once again, remember if you feed the woofer a full range signal, then that 10" driver will be competing with your 2" or 3" midrange (and tweeter even). First this results in wasted energy and secondly, if the woofer is louder than the midrange.... will you still hear the midrange?

Oh, you also asked about piezo tweeters. Those are so efficient and have such high impedance that they usually don't even require a filter cap and the system doesn't even really notice them there. At least on the old designs. To keep the system in proper balance, I have heard that you may need to parallel resistors with piezos so that the system works as intended. You may want to research and google this if you are considering piezos although to my ears, I don't like them all that much as I like my tweets to dip a bit lower than piezos are capable of.
 

Lasonic TRC-920

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jimmyjimmy19702010 said:
So is the problem that the box doesn't seem to play loud enough?
Chances are that amp is probably on the weedy side. Maybe splice in a new amp !?

Your existing woofers are probably receiving a full range signal with a simple cap on the tweeter. As Norm was saying, sending highs to the woofer is a waste of power as the woofers ability to reproduce highs is severely limited.

If you go with an off the shelf 3 way passive crossover, the driver will only be fed lows which is a good thing.

You could salvage a 3 way crossover from a low end home HiFi speaker that utilises 4 or 6 ohm speakers. Use the mids and tweeters from the host cabinets and your existing dynasty drivers.

That way, you know the crossover is matched to the mid and tweeter speakers.
Thank you Jimmy, that's a great way to source some already balanced components. Time to get back on the garage sale circuit

Superduper said:
Ok, so just in case I wasn't clear before. If you were to parallel or series connect multiple speakers together, you can generally rely on ohms law to do the calculation. But speakers aren't usually connected in that way. If you parallel tweeters to woofers without some kind of filter, they would blow. On midranges, you generally don't want the lows or the highs since they their forte is mid z's. Too low and they'll fart, and too high and they simply won't be effective. And while low z drivers aren't hurt by mid or high signals, that's not their specialty. So on cheap devices like boomboxes, to keep parts count (and manufacturing costs) down, woofs generally get the full signal. The tweets get a high-pass filter that might chop off (roll off, actually) signals below 6, 8, 10khz... some level depending upon the value of the capacitor and the tweeter impedance. What all this means is that unlike if you were to simply inject a straight 1khz signal and measure impedance, a dynamic signal simiply can't be easily measured using ohms law since the tweeter isn't really even a factor if/until the signal includes highs that is passed through. And what do you listen to anyway? 10 people and you get 10 answers so the effect on the amplifier is.... it depends.

=====================

To your question, you can buy pre-made crossovers or you can fabricate your own using software that you can buy (parts express sells the software). The software calculates the values of the crossover parts to use as well as the circuit diagram based upon the specs of the drivers you will be using. Of course if you buy your own tweets and midrange, those specs are available but the woofer specs will be an unknown. Although not 100% perfectly tailored to your own setup, premade crossovers generally work well enough and should be an improvement over no-crossover. Off the shelf crossovers are usually designed for 4 or 8 ohm systems. You can mix other impedance drivers into the mix instead but the crossover points will change and system might sound "off".

As for cutoff, there is always some amount of overlap or soft roll-off. You never want a hard cut off, it will most likely be audible. Simplest thing you can do is just get a premade crossover and tinker from there. Also, you may find that the tweets or mids are too bright. This frequently occurs because high efficiency tweeters are easier to find than high efficiency woofers and midranges. Also, the ears are more sensitive to midrange (a 50 hz signal even at high current isn't likely to cause too much distress but a 1khz signal at moderate to high signal levels will be piercingly loud and unbearable). To combat this, if your drivers aren't matched well in sensitivity, you may need to series a resistor inline with either the midrange or tweeters to attenuate them a bit. Or you can buy what they call "L Pads".

Additionally, the woofers can be operated with full range signal. But your crossover will likely include inductors that will attenuate the higher frequency if you use it the way it's intended. If you buy off the shelf crossovers, you will find the following connections: 1-input, 2-woofer, 3-midrange, 4-tweeter. Woofers usually get a low pass signal, tweeters a high pass signal and midranges get a band-pass signal. The only way I see you getting full range to the woofer is if you decide not to use the connections at the crossover intended for the woofers. Let the woofs do the job they are designed to do and let the other drivers do their respective part. Once again, remember if you feed the woofer a full range signal, then that 10" driver will be competing with your 2" or 3" midrange (and tweeter even). First this results in wasted energy and secondly, if the woofer is louder than the midrange.... will you still hear the midrange?

Oh, you also asked about piezo tweeters. Those are so efficient and have such high impedance that they usually don't even require a filter cap and the system doesn't even really notice them there. At least on the old designs. To keep the system in proper balance, I have heard that you may need to parallel resistors with piezos so that the system works as intended. You may want to research and google this if you are considering piezos although to my ears, I don't like them all that much as I like my tweets to dip a bit lower than piezos are capable of.
OK, I understand what you're saying. This answers a ton more questions in my mind.

I might start looking for a set of bookshelf speakers, 3 ways, with 8"-10" woofers. Then pull them apart, see what I am working with.

I'll also look for passive crossovers. Maybe some with adjustable frequencies??? Do they make those? Would be nice to tune the box with a knob on the crossovers
 

Superduper

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If you can get some bookshelf speakers for cheap and want to give it a try, go ahead but you might be better off just buying new drivers with the specs you want. Sure new crossovers are going to be universal/generic ones so it might not be 100% tailored perfect for your exact driver, but I think you forget that this is a boombox and not high-fidelity home stereo. Even if you found a bookshelf speaker that sounds decent, what happens when you mate it with a wheely woofer? And what happens when you stuff it inside a free air plastic wheely shell with no stereo isolation between the drivers? See what I mean, nothing is 100% ideal and everything is going to be a compromise anyhow. BTW, you'll note that if you were to build your own crossover, the values of the inductors, capacitors etc. specified by the software isn't likely going to be available in those exact values. Generally speaking, you are going to just get the closest "standard" value you can find.

As to your other question, I am not aware of any passive crossovers that are adjustable other than attenuation of certain drivers. That's because actual crossover points are dictated by the values of the capacitors and inductors and while resistance is easily adjustable with the right wattage potentiometer(s) variable capacitors or inductors in those sizes just aren't available to my knowledge, nor would they be cost practical to use if they were. However, adjustable "active" crossovers are available. The difference between active and passive crossovers is that passive is unpowered and is located between the amplifier output and the speakers whereas active crossovers need power to operate and only tailors low level signals (line level) and resides between a preamp and power amp input. Additionally, active crossovers are intended to be used with multiple amplifiers, each amplifier powering a specific driver whose input signal was tailored by the crossover for that driver.

If you aren't happy with the universal crossovers, you can always tailor the crossover points by replacing the specific components that affect that driver, or you can simply buy bare crossover PCB's and populate them yourself using components with values right for your application. That way, you aren't wasting good expensive components that will be replaced anyway. However, you may find that universal ones might be the best value since crossover components are particularly expensive, especially good ones.
 

Lasonic TRC-920

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Superduper said:
If you can get some bookshelf speakers for cheap and want to give it a try, go ahead but you might be better off just buying new drivers with the specs you want. Sure new crossovers are going to be universal/generic ones so it might not be 100% tailored perfect for your exact driver, but I think you forget that this is a boombox and not high-fidelity home stereo. Even if you found a bookshelf speaker that sounds decent, what happens when you mate it with a wheely woofer? And what happens when you stuff it inside a free air plastic wheely shell with no stereo isolation between the drivers? See what I mean, nothing is 100% ideal and everything is going to be a compromise anyhow. BTW, you'll note that if you were to build your own crossover, the values of the inductors, capacitors etc. specified by the software isn't likely going to be available in those exact values. Generally speaking, you are going to just get the closest "standard" value you can find.

As to your other question, I am not aware of any passive crossovers that are adjustable other than attenuation of certain drivers. That's because actual crossover points are dictated by the values of the capacitors and inductors and while resistance is easily adjustable with the right wattage potentiometer(s) variable capacitors or inductors in those sizes just aren't available to my knowledge, nor would they be cost practical to use if they were. However, adjustable "active" crossovers are available. The difference between active and passive crossovers is that passive is unpowered and is located between the amplifier output and the speakers whereas active crossovers need power to operate and only tailors low level signals (line level) and resides between a preamp and power amp input. Additionally, active crossovers are intended to be used with multiple amplifiers, each amplifier powering a specific driver whose input signal was tailored by the crossover for that driver.

If you aren't happy with the universal crossovers, you can always tailor the crossover points by replacing the specific components that affect that driver, or you can simply buy bare crossover PCB's and populate them yourself using components with values right for your application. That way, you aren't wasting good expensive components that will be replaced anyway. However, you may find that universal ones might be the best value since crossover components are particularly expensive, especially good ones.
OK, this is all pretty much what I thought. We are both on the same page in the fact that this is a "Boombox" and not even a good one (just a big one). I'm not looking for audiophile, just mids and highs that match the woofer. I think with some mids that CRANK this box would be tons louder (even if it's not cleaner). And since it's only use is outside, in a crowd with people screaming and cars driving by, I'm sure any step forward would be HUGE, plus I can always go back.

I did go do some research on crossovers after your first post in this thread, so I'm starting to understand what I will need.

I guess the question is...

What should the frequency be for each speaker?

I can build me own and test it.

And since this radio has an EQ, I only need to get close right? Then I can EQ the rest?
 

Superduper

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Oh wait, hold on. Are you hoping to increase volume by adding a single TWO INCH midrange to the network? I'm not sure that it's going to accomplish what you are wanting. You want loud piercing midrange, you'll probably need to go at least 5-1/4" to 6-1/2" drivers. In my opinion, you aren't going to get real loud SPL out of 2" cone type drivers. I mean, you now have 10' woofs. If they aren't loud enough for you, how are you going to get that by adding a couple of 2, count 'em TWO inch drivers. Now, if you want to add some compression drivers and can find a way to rig them into your setup, their SPL sensitivity is unmatched by the cone drivers. For example, these here are 1" compression drivers and have sensitivity of 105db. However, they are designed to be used with horns and not sure how it would sound without the lens. Maybe you can experiment and see? Not suggesting you use these, but you can search more and see if something like these could work for you. The frequency response on these daytons goes from 1khz to 20khz but on the other hand, they weigh 4.5 lbs each so that's like adding 10 pounds to your boombox before the crossovers which probably weigh quite a bit as well due to the inductors which are basically coils of copper wire.

http://www.parts-express.com/dayton-audio-dt250p-8-1-polyimide-compression-horn-driver-1-3-8-18-tpi-8-ohm--270-406

Your other alternative is to beef up the amp setup. To my recollection, the wheely amp is not exactly a wimp, but it isn't nearly a powerhouse that you would expect either, commonly suffering from insufficient supply current and/or just simply poor circuit design. A class D or T amp might help you get a bit more output with less distortion. HOWEVER, I caution you (and all others contemplating similar upgrades) that in order to get double the perceived loudness, you need like 8 - 10 times the power. By that measure, you would need 80 to 100 watts to double the volume prevously obtained from 10 watts. That's why when folks get all giddy and boast about getting an additional few watts from their boombox by stuffing 2 ohm woofers into their setup, I can't help but roll my eyes. Firstly, I promise you that the difference between 10 and 15 watts is barely audible to our human ears. Secondly to stress and risk blowing these vintage amps to extract that extra 1db or 2db is plain silly in my opinion. It's penny wise/pound foolish. Installing more efficient drivers is a far more effective way to get increased SPL out of your setup than dropping impedance to extract more juice out of the amp. I mean, think about it... you need 3db increase just to begin to percieve an increase in loudness. You need 10db increase to get double the perceived loudness. This website suggests you need 10x the power to get an increase of 10db.

http://geoffthegreygeek.com/amplifier-power/

With that in mind, wouldn't it be a far more effective and easier way to increase loudness by simply selecting more efficient drivers?

On the other hand, going back to those Dayton (and similar drivers), I'm guessing that 50 watts into one of those compression drivers with 105db spl would be painfully loud. So the solution might be a combination of getting the most efficient drivers you can and mate them with the drivers with the highest SPL.
 

baddboybill

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All I gotta say is how the heck does Norm type so much and not complain about his hands or fingers hurting. Lol😄😄😄. I gotta say though he knows his stuff for sure 😜. Good luck with project Chris 👍


Bad Boy Bill
 
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