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Speakers Z matching
- Thread starter SFM-Ptgal
- Start date
No, it's not really a cure. Actually it's not a problem to connect a 4 Ohm speaker provided you don't run the amp too hard!
The problem with the low impedance speaker is that you're going to draw more current which heats the amp more. If you are listening to lower and moderate volumes, this is not a problem. It becomes a problem when your driving the amp hard as you might overheat and blow the output resistors. IOW, use for home listening, don't use at parties!
Regards,
Goran Tomas
The problem with the low impedance speaker is that you're going to draw more current which heats the amp more. If you are listening to lower and moderate volumes, this is not a problem. It becomes a problem when your driving the amp hard as you might overheat and blow the output resistors. IOW, use for home listening, don't use at parties!
Regards,
Goran Tomas
Then you have a problem...
Is there no way to assure the amplifier won't be driven hard? For example, adding a resistor to the volume potentiometer will limit how loud the amplifier is driven even when the volume knob is fully open.
You could get an impedance matching transformer for the loudspeakers, but those that sound good are costly.
Could you get higher impedance speakers?
Could you get a proper amplifier and use it to drive speakers?
Adding a resistor is the last solution, IMO. Firstly you would have to use a resistor that has high enough power rating as you would dissipate half (in case of 4 Ohm resistor) of amplifier power heating the resistor. The resistor would also have negative effect on the damping which would somewhat affect the sound. If you ask me, not really a good solution.
Regards,
Goran Tomas
Is there no way to assure the amplifier won't be driven hard? For example, adding a resistor to the volume potentiometer will limit how loud the amplifier is driven even when the volume knob is fully open.
You could get an impedance matching transformer for the loudspeakers, but those that sound good are costly.
Could you get higher impedance speakers?
Could you get a proper amplifier and use it to drive speakers?
Adding a resistor is the last solution, IMO. Firstly you would have to use a resistor that has high enough power rating as you would dissipate half (in case of 4 Ohm resistor) of amplifier power heating the resistor. The resistor would also have negative effect on the damping which would somewhat affect the sound. If you ask me, not really a good solution.
Regards,
Goran Tomas
You do have a problem. A lot of earlier solid state amplifiers - like the ones built into vintage consoles- tend to self destruct if run at too low an impedance. Your best bet is to find some 8 ohm (or higher) speakers. Really...
The second best solution is to use some beefy transformers. There are some out there intended for the home theater and sound reinforcement markets that can do the job. Good ones are expensive.
You could try taking a 70 volt (or in Europe a 100 volt) line to voice coil transformer and use it as an autotransformer. These are commonly used in distributed paging and background music systems. You will need one that is high enough wattage to handle the full output of the amplifier and has multiple taps on the secondary (loudspeaker side). You will simply ignore the 70 (or 100) volt line side, and use the common and 8 ohm tap for the amplifier and the common and 4 ohm tap for the loudspeaker. I would do this with caution, while watching the temperature of your amplifier output transistors. If they get alarmingly hot, stop before you blow something up.
Another old trick is to put a 12 volt light bulb in series with the speaker. An 1126 or 1127 tail light bulb usually works well, but some experimenting is required to get it right. When the current drain is very low - that is low volume - the filament is a very low resistance, usually an ohm or less. At low volume, it doesn't make much difference in how it sounds, but as Goran suggests, any added resistance messes with your damping factor. As you push the amplifier harder, the filament heats up and it's resistance goes up. This current limits the amount of signal going to the speaker. It's an old trick that is often used to protect cheap (and sometimes expensive) sound reinforcement and Hi-Fi speakers. It should help protect your amplifier too.
Something else you need to know is that even an "8 ohm" loudspeaker is likely to have a serious impedance dip at its resonate frequency. That dip will always be at a lower bass frequency, usually under 100 Hz, but it depends on the design of the enclosure and the components used. It isn't at all unusual for them to dip to 6 ohms and a lot dip a lot lower than that. This can cause some real problems for some amplifier designs, especially early solid state versions like you find in many broadcast consoles.
Perhaps your simplest solution would be to use an external amplifier, rather than the one built into the console. Most modern designs are quite happy at 4 ohms and a lot think loads as low as two ohms are perfectly acceptable.
The second best solution is to use some beefy transformers. There are some out there intended for the home theater and sound reinforcement markets that can do the job. Good ones are expensive.
You could try taking a 70 volt (or in Europe a 100 volt) line to voice coil transformer and use it as an autotransformer. These are commonly used in distributed paging and background music systems. You will need one that is high enough wattage to handle the full output of the amplifier and has multiple taps on the secondary (loudspeaker side). You will simply ignore the 70 (or 100) volt line side, and use the common and 8 ohm tap for the amplifier and the common and 4 ohm tap for the loudspeaker. I would do this with caution, while watching the temperature of your amplifier output transistors. If they get alarmingly hot, stop before you blow something up.
Another old trick is to put a 12 volt light bulb in series with the speaker. An 1126 or 1127 tail light bulb usually works well, but some experimenting is required to get it right. When the current drain is very low - that is low volume - the filament is a very low resistance, usually an ohm or less. At low volume, it doesn't make much difference in how it sounds, but as Goran suggests, any added resistance messes with your damping factor. As you push the amplifier harder, the filament heats up and it's resistance goes up. This current limits the amount of signal going to the speaker. It's an old trick that is often used to protect cheap (and sometimes expensive) sound reinforcement and Hi-Fi speakers. It should help protect your amplifier too.
Something else you need to know is that even an "8 ohm" loudspeaker is likely to have a serious impedance dip at its resonate frequency. That dip will always be at a lower bass frequency, usually under 100 Hz, but it depends on the design of the enclosure and the components used. It isn't at all unusual for them to dip to 6 ohms and a lot dip a lot lower than that. This can cause some real problems for some amplifier designs, especially early solid state versions like you find in many broadcast consoles.
Perhaps your simplest solution would be to use an external amplifier, rather than the one built into the console. Most modern designs are quite happy at 4 ohms and a lot think loads as low as two ohms are perfectly acceptable.
Yup, it's a Stereo 80. A long time ago I've tried 8 ohm speakers (PC speakers) with no complaints from the console. For some reason while testing a 16 ohm, or so, speaker I've blown a module monthes ago. At the moment I'm monitoring with headphones only. The reason for the 4 ohms speakers is this http://www.behringer.com/EN/Products/1C-BK.aspx Cheap for my intentions. 4 Ohms only.
I don't mind to get or to build a velleman amplifier do drive them. From what was told here somewhere, I can connect it to the console speaker output, right? If so I think thats the easiest way...
I don't mind to get or to build a velleman amplifier do drive them. From what was told here somewhere, I can connect it to the console speaker output, right? If so I think thats the easiest way...
R
RolfTaylor
Guest
Or, you can buy 2 pairs of the speakers and run two in series for left and the same for right.
4+4 = 8! Voila
4+4 = 8! Voila
Why not just get yourself a second 4 Ohm monitor and place it in SERIES (not parallel) with the first? The amp would then "see" 8 Ohms...
EDIT: Didn't see Rolf's post. Looks like he had already made the suggestion.
EDIT: Didn't see Rolf's post. Looks like he had already made the suggestion.
You could simply buy some powered speakers from Behringer, M-Audio or lots of others. It would solve your impedance match problem and probably sound better too. Just terminate the Gates amplifier with a resistor to keep it from going into some kind of weird oscillation, 10 ohms at 10 watts should do the trick, and bridge it with the powered speaker input.
It will probably sound better than the set-up you have proposed, and you have done nothing to damage the console.
It will probably sound better than the set-up you have proposed, and you have done nothing to damage the console.
If you are looking for speakers this is my choice. http://www.madisound.com/ Wide selection. Built many speakers with their components. Love the Vifas.
I would go with the light bulb trick in a pinch as previously suggested. That trick has been the favorite tweeter saver mod for years. I did many permanent installations years ago with that mod for high power professional systems. It beats having to climb to high points to replace blown high frequency devices. Community was one of the early manufactures to build high quantities commercially with light bulb limiters for the tweeters. We used auto bulbs however they would allow too much current to flow in this case.
It acts as a soft current limiter. It should not affect the dampening factor that much in normal operation.
I would not use 4 ohm speakers on one of those old amplifiers. 16 ohm speakers would be much better.
I would go with the light bulb trick in a pinch as previously suggested. That trick has been the favorite tweeter saver mod for years. I did many permanent installations years ago with that mod for high power professional systems. It beats having to climb to high points to replace blown high frequency devices. Community was one of the early manufactures to build high quantities commercially with light bulb limiters for the tweeters. We used auto bulbs however they would allow too much current to flow in this case.
It acts as a soft current limiter. It should not affect the dampening factor that much in normal operation.
I would not use 4 ohm speakers on one of those old amplifiers. 16 ohm speakers would be much better.
I second the powered monitors. Many people don't know that these have correction for spectral and phase response built in, in addition to quite healthy amps for each driver in most cases, and protection limiters on each driver's amp so you don't blow em. The bang for your buck is really great because of this, compared to bi-amping, correcting, and protect limiting a pair of unpowered speakers. Comparing to uncorrected unpowered speakers + amp at the same price, and the huge difference is audio quality/transparency.
The Behringer Truth B3031A would be my suggestion if you want to keep things cheap but good. They ought to sound great, since they copied so many good things. Tired of people slamming Behringer based only on the grounds of quality of sound or product, because in that regard... for the class of products they are competing with... they totally bring it.
The Behringer Truth B3031A would be my suggestion if you want to keep things cheap but good. They ought to sound great, since they copied so many good things. Tired of people slamming Behringer based only on the grounds of quality of sound or product, because in that regard... for the class of products they are competing with... they totally bring it.
I would go for those if I could. They are a copy of the Genelec 1032A (I work with them at work)but much more cheaper. They've crossed the tape age, suffered well from high-speed tape cueing and other abuses and have survived. Only issue so far was the membrane separating from the outer ring, on the main speaker. Solved with a special glue...
Before the Genelecs they used standard speakers... 24 hour news radio, 2 editing studios, a tweeter per week was the rule in the 80's...
Before the Genelecs they used standard speakers... 24 hour news radio, 2 editing studios, a tweeter per week was the rule in the 80's...
We have three sets of these in my radio station. They've been great. No problems and everyone likes they way they sound. They also have a cheaper version that is about $100 for a pair. Not as good, but probably "good enough" for radio.Jesse Graffam said:The Behringer Truth B3031A would be my suggestion if you want to keep things cheap but good. They ought to sound great, since they copied so many good things. Tired of people slamming Behringer based only on the grounds of quality of sound or product, because in that regard... for the class of products they are competing with... they totally bring it.
The Behringer speakers SFM linked to are their version of a JBL Control 1. They are OK, but nothing to write home about, other than the price, which is "dirt cheap." For a little more $, you could do a lot better.
They don't, it's an active powered speaker, so it all happens in the DSP chip. Limiters included. As far as any impedance variance across the spectrum, it doesn't effect the line level input at all.
The amp design on these is BASH, if you were wondering. Big bang for the buck with high dampening factor and low distortion. Toroidal in the PSU of course.
The amp design on these is BASH, if you were wondering. Big bang for the buck with high dampening factor and low distortion. Toroidal in the PSU of course.
Let me be the black sheep in the herd and suggest you actually buy a pair of Genelecs! Not only it is the genuine design (and Genelec people sure know how to design active speakers, having practically invented the category) and not a copy, but also because of the quality and durability. You will probably be using them for decades to come all the time enjoying the high quality sound...
There, I've said it!
Regards,
Goran Tomas
There, I've said it!
Regards,
Goran Tomas
Goran Tomas said:Let me be the black sheep in the herd and suggest you actually buy a pair of Genelecs! Not only it is the genuine design (and Genelec people sure know how to design active speakers, having practically invented the category) and not a copy, but also because of the quality and durability. You will probably be using them for decades to come all the time enjoying the high quality sound...
There, I've said it!
Regards,
Goran Tomas
I'm solidly of the same opinion as Goran. Unless you're looking for cheap utility speakers, that can sound like...whatever,
I will always go with as neutral and as long-term reliable a model as I can afford. And to me, for well over a decade, that has pointed directly to Genelec.In 2004, I even designed TransLanTech's NAB booth to fit a pair of them in the panels.
No speaker is truly neutral, but I at the least know what Genelecs sound like, and as such I can depend upon them as a very useful, repeatable sonic reference. They are not cheap and heaven knows Behringer's knock-offs may be perfectly fine for 90% of the uses, but I KNOW the Genelecs are here for the long haul.
Kind Regards,
David
Jesse Graffam said:They don't, it's an active powered speaker, so it all happens in the DSP chip. Limiters included. As far as any impedance variance across the spectrum, it doesn't effect the line level input at all.
The amp design on these is BASH, if you were wondering. Big bang for the buck with high dampening factor and low distortion. Toroidal in the PSU of course.
I was referring the speakers that the original poster was talking about. They are very inexpensive passive speakers, similar in appearance to a JBL Control 1. No amp or DSP included. That's the problem, they are a 4 ohm box and his board’s built in amplifier isn't happy with the 4 ohm load.
Purchasing speakers is a very personal thing. There are lots of very good ones and I concur that the Genelec's are great. Buy the ones that sound best to you, within your price range. If you can afford the Genelec’s, then go for it.
Unless I have misinterpreted the original poster's question, I believe he does not want to spend a lot of money on this. That's why I suggested that he spend a bit more and get some powered Behringer speakers. There are several to choose from in their line that are powered. The cheapest are labeled "multi-media," while better versions are referred to as Studio Monitors.
You probably won't find any of these in any major studio, but for broadcast confidence monitoring they work well and are very reasonably priced. If you can afford better speakers, by all means do so. Sometimes you don't always get what you want, but you can have what you need...
Incidentally, my oldest pair of Behringer "Truth" powered monitor speakers are going on 9 years of 24/7 operation. No problems so far....
If you can afford Genelecs that aren't plastic, get a pair of Barefoots or PMCs, and enjoy much more transparent and impactful sound.
http://www.barefootsound.com/barefoot/
http://www.pmc-speakers.com/
I'm not a fan of the plastic Genelecs though. I used to own a 2.1 1032A/7070A setup, and it was ok, but for the price there's a lot better stuff out there now. It would have been neat to see them innovate a new flagship line, instead of the direction they headed to, but I wouldn't doubt they made some good money doing it.
http://www.barefootsound.com/barefoot/
http://www.pmc-speakers.com/
I'm not a fan of the plastic Genelecs though. I used to own a 2.1 1032A/7070A setup, and it was ok, but for the price there's a lot better stuff out there now. It would have been neat to see them innovate a new flagship line, instead of the direction they headed to, but I wouldn't doubt they made some good money doing it.
yes, not much money for the hobby... as I said b4 my intentions are not for the near future. What I find strange is that the Stereo 80 runned with 2 different pc speakers (the passives from each set) and the console didn't complaint (8 ohm)...
You can see them here: http://www.youtube.com/watch?v=Uoxc9wlqjd8
You can see them here: http://www.youtube.com/watch?v=Uoxc9wlqjd8
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