Hi folks,
I'll keep this simple. I'm building line arrays, 21 4" mids crossing to 7' electrostatic tweeters around 1500hz. I need some low power 2 ohm stable amps as i want to parrallel 3 of the mids (they are 6 ohm) anyone know where i can get something like this at a reasonable price? Every amp i've seen so far is high power and usually car audio.
Is there a class D that would do this?
were talking about quite a few amps.
I'll keep this simple. I'm building line arrays, 21 4" mids crossing to 7' electrostatic tweeters around 1500hz. I need some low power 2 ohm stable amps as i want to parrallel 3 of the mids (they are 6 ohm) anyone know where i can get something like this at a reasonable price? Every amp i've seen so far is high power and usually car audio.
Is there a class D that would do this?
were talking about quite a few amps.
A quick browse through Texas Instruments' offer showed THIS chip as having a 2-ohm minimum load, described as "automotive amplifier". This one has single-ended inputs, and its brother (TAS5424A) has differential inputs. That is, if you're willing to go "full DIY" 
Hmmm... On a second look, these seem to be I2C controlled, so that might be a disadvantage. A more detailed browse through the datasheet might show if it's possible or not to use these chips on their own.
Good luck with the project,
Chris
Hmmm... On a second look, these seem to be I2C controlled, so that might be a disadvantage. A more detailed browse through the datasheet might show if it's possible or not to use these chips on their own.
Good luck with the project,
Chris
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Thanks Chris,
this is probably exactly what i need but full diy is a bit out of my league.
I was thinking along the lines of something like the sure type modules but with 2 ohm stability.
I'll be running active pc crossovers with 7 of these amps in total this will allow me to roll off the outer drivers from 0 db down to -12 db at the outer edges.
this is probably exactly what i need but full diy is a bit out of my league.
I was thinking along the lines of something like the sure type modules but with 2 ohm stability.
I'll be running active pc crossovers with 7 of these amps in total this will allow me to roll off the outer drivers from 0 db down to -12 db at the outer edges.
Hi Andrew,
Just a little bit on the pricey side for 21 amps.
I did look at the little 2w sure amps
2watt D-Class mono audio amplifier board EUA2005, 2pcs_Audio Amplifier Boards_Audio Amplifier and other Audio Boards_RF and Audio, Video Equipments_Sure Electronics' Webstore
but not sure of the quality of these.
Also looked at these
2*8W @ 8ohm/4ohm, MPS7720 D-class Audio Amplifier Board_Audio Amplifier Boards_Audio Amplifier and other Audio Boards_RF and Audio, Video Equipments_Sure Electronics' Webstore
but once again not sure on the quality of sound - has anyone tried them.
Please bear in mind that with 21 driver per side i'm not going to be putting much power through them. The drivers themselves are rated for 75w rms but i doubt if i'll ever push them past 1 w
I wonder if at the power level i'll be using them the 2x15w would do 3ohm? i.e 2 drivers parallel which would mean 11 amplifiers?
Just a little bit on the pricey side for 21 amps.
I did look at the little 2w sure amps
2watt D-Class mono audio amplifier board EUA2005, 2pcs_Audio Amplifier Boards_Audio Amplifier and other Audio Boards_RF and Audio, Video Equipments_Sure Electronics' Webstore
but not sure of the quality of these.
Also looked at these
2*8W @ 8ohm/4ohm, MPS7720 D-class Audio Amplifier Board_Audio Amplifier Boards_Audio Amplifier and other Audio Boards_RF and Audio, Video Equipments_Sure Electronics' Webstore
but once again not sure on the quality of sound - has anyone tried them.
Please bear in mind that with 21 driver per side i'm not going to be putting much power through them. The drivers themselves are rated for 75w rms but i doubt if i'll ever push them past 1 w
I wonder if at the power level i'll be using them the 2x15w would do 3ohm? i.e 2 drivers parallel which would mean 11 amplifiers?
to start with i probably dont want to go over about £200 for amps bearing in mind i also have to get a decent amp to drive the electrostatic tweeter panels and transformer and ill be driving 2 sub/ infra bass speakers probaly inverted tapped horns. - i've a pair of dayton dvc 15" sub here for that purpose and have my eye on one of the new cerwin vega 2800w amps for sub duties.
eventually once all the prototyping etc is done ill move up to better amplification but i don't like the idea of running the speakers series and parrallel to a single amp - i'd like something a little more refined particularly since it will allow a lot more control while testing.
crossover duties are through the pc - currently running a pair of soundblaster audigy zs cards with the kx project drivers but one of these is being swapped out for an autotrax card thats on the way.
i'll be running extremely steep filters with phase control and convolution per per speaker bank.
So far the single prototype sounds great but i'm still tweaking baffle arangement.
btw these are open baffle with the curved esl tweeter acting as one side of the baffle in a half torus arangement.
lots of work still to be done.
If your speaker design ends at 2ohm, you need a bit more than just 2ohm stable amps
A 2ohm stable amp will do good at driving 3-4ohm
Or bridged to drive minimum of 4ohm
What you suggest is like driving 8ohm speakers that in reality are 6ohm, like many speakers, and use amps that cant cope with 4ohm but only 8ohm stable
Many 150-200watt AB amp designs driven with lower voltage to make say 50watt will do what you want
With big heatsinks
You might be able to do the same with tough ClassD amps
Like say a 200-300watt 2ohm stable amp design, but built to do about 60-80watt, and I think you might be safe
A 2ohm stable amp will do good at driving 3-4ohm
Or bridged to drive minimum of 4ohm
What you suggest is like driving 8ohm speakers that in reality are 6ohm, like many speakers, and use amps that cant cope with 4ohm but only 8ohm stable
Many 150-200watt AB amp designs driven with lower voltage to make say 50watt will do what you want
With big heatsinks
You might be able to do the same with tough ClassD amps
Like say a 200-300watt 2ohm stable amp design, but built to do about 60-80watt, and I think you might be safe
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Well, say you have two amps each with maybe like 10khz input impedance
And you paralel them into the same preamp output
The preamp will see a 5kohm load instead of 10kohm
Some tough preamp designs will be fine, but many wont
You may have amps with higher input impedance, like say 20kohm
But then, you are talking about multiple amps, more amps than just two
And you paralel them into the same preamp output
The preamp will see a 5kohm load instead of 10kohm
Some tough preamp designs will be fine, but many wont
You may have amps with higher input impedance, like say 20kohm
But then, you are talking about multiple amps, more amps than just two
Oh, I may have misunderstood it
I read it as one amp each driver, like someone suggested
I can see now it probably means ONE single amp only
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Not sure I follow that question.
He mentioned there will be 21 drivers per side @ 6-ohm each. If he made 7 sets of 3 parallel drivers, that would make a combined load of ~14-ohm.
I don't see any major problem with a final 14-ohm load; unless he planned on doing some sort of power tapering using the gain of each individual amp.
EDIT: Didn't read your last post until after I finished.
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Power tapering is one of the reasons i'm going this route.
the other is to try and keep all the connections parallel if possible.
it is my understanding that series and series/parallel can have adverse effects on speakers and is a technique used in the live perfomance world to change the sound on amplified guitars etc. Apparently it can lead to an 'edgier' sound which of course i don't want.
It would be easy for me to just wire the drivers in a mixture of parallel and series and run them of 4.8 ohms - 5 parrallel - 4 X series or some other configuration with a single driver on 6 ohms. but this wont allow me to taper adequately. In sets of 3 i can at least tweak to a certain extent.
It's really all about flexibility allowing me to test a number of different configurations and getting the best sound a diyer can achieve within a pretty tight budget.
the other is to try and keep all the connections parallel if possible.
it is my understanding that series and series/parallel can have adverse effects on speakers and is a technique used in the live perfomance world to change the sound on amplified guitars etc. Apparently it can lead to an 'edgier' sound which of course i don't want.
It would be easy for me to just wire the drivers in a mixture of parallel and series and run them of 4.8 ohms - 5 parrallel - 4 X series or some other configuration with a single driver on 6 ohms. but this wont allow me to taper adequately. In sets of 3 i can at least tweak to a certain extent.
It's really all about flexibility allowing me to test a number of different configurations and getting the best sound a diyer can achieve within a pretty tight budget.
Well, out of the two small boards you previously mentioned, I would have to go with the MPS7720. I've heard the other 2W amp produces a nasty amount of noise.
Be aware the MPS7720 has capacitor coupled outputs (single supply, single ended). It should be fine at 2R if you keep the supply voltage low enough (hopefully).
Be aware the MPS7720 has capacitor coupled outputs (single supply, single ended). It should be fine at 2R if you keep the supply voltage low enough (hopefully).
Sorry, I thought it was explained
It was related to a previous suggestion of using multiple amps, or I mistakenly thought it was
I misunderstood, maybe because of a bit shortened english
With that many drivers, you may need more power than you realise
I would say a minimum of 30watt/8ohm, making 100watt into 2ohm
Any good AB amp with just 2 or maybe 4 tough output devices will do that, with a big heatsink
But you may realise that even if it survives 2ohm, it may loose some of its quality
With 2ohm, it might just be only 1.8ohm, or even 1.5ohm
2.5-3ohm might work much better
Im not sure why you say "on a tight budget", with that many 4" and electrostatic tweeters
What is a tight budget
Every time I have calculated such with even much less drivers, it gets expencive very fast, even with relatively cheap drivers
I would say a minimum of 30watt/8ohm, making 100watt into 2ohm
Any good AB amp with just 2 or maybe 4 tough output devices will do that, with a big heatsink
But you may realise that even if it survives 2ohm, it may loose some of its quality
With 2ohm, it might just be only 1.8ohm, or even 1.5ohm
2.5-3ohm might work much better
Im not sure why you say "on a tight budget", with that many 4" and electrostatic tweeters
What is a tight budget
Every time I have calculated such with even much less drivers, it gets expencive very fast, even with relatively cheap drivers
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I think i'll go with the sure 4X 100w boards and try one with 2 mids in parallel to start with test for a week or 2 and if all is okay ill order all that i need with a couple of spares. They seem to offer the best bang for buck and having too much power wont cause as much of an issue as too little will.
As for tight budget - my 40th birthday presents consist of
64 4" wharfdale full range drivers
2 15" dayton dvc subs
one cerwin vega cv 2800 (not ordered yet)
i already have the step up transformers and 4 other amps for the tweeters and the custom metal will be ordered after xmas.
now thats a proper birthday present even though my birthdays not until march i hope to unveil the finished speakers at the party - I love my wife
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