What amplifiers to use for 3.5 way active speakers.

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mtidge

mtidge

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Joined 2018
bellarossafabrica.net
This is more a thought experiment, I have built a couple of 3 way speakers with passive crossovers. I think about making them active, but I hit the same wall, price. For a 3.5 way setup I would need 8 channels of amplification. I think class D would work for me, but every option I look into, new power amps, kits, raw amp boards, Hypex plates or used multi-room amplifiers it always ends up costing $1,200.00 USD or more. Then I need to add a 2 in and 8 out DSP like the Aurora and I stop thinking and stick with my roughly $300.00 3 way passive crossovers. Am I missing something or is active still just expensive?
 
mtidge

mtidge

Member
Joined 2018
bellarossafabrica.net
Still looking for 8 channels of quality amplification for a reasonable price. Here is what I've considered.

IcePower

2 ICEpower 200ASC Class D Audio Amplifier with Power Supply Module 1 x 200W
2 ICEpower 200AC Class D Audio Amplifier Module 1 x 200W
1 ICEpower 50ASX2SE Class D Audio Amplifier with Power Supply Module 2 x 50W

Not cheap, but I'm concerned about input buffering and the fact that 200ASC and 50ASX2SE have different gains. The 50ASX2SE would be for the tweeters, but I would still need to cut the woofer levels to match.

The Emotiva BasX A-700
I would have to go 3 way and not 3.5 way and now Emotiva doesn't even list the 7 channel on there site any more.

Hypex

Plate amps , I don't want or have room to put them in the cabinets so I would have to build them into a chassis. Also, not 3.5 way, and different gain on the tweeters.

Can't get the Hypex boards, they OEM only, would have to get a complete amp from an OEM assembler, not cheap.

Any brilliant ideas out there? I don't think Shure/Womdom/Dayton is the answer either.
 
D

DougL

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Joined 2004
Just a guess, but I think you are overestimating your power requirements.
I did a 3 way OB with a pair of 3 Channel T amps. They were rated 30 WPC.
All the drivers were ~ 90 DB efficient. I had to be careful not to make my ears ring.

Target something in the 25 to 50 WPC. Use 4 identical amps.
Without the reactive crossover, the amps are much better behaved and sound better.
The Dayton DSPB is a very good suggestion IMHO.
$250 with the power supplies for 8 channels x 50 watts.

Good Luck with whatever you decide.

Doug
 
hifijim

hifijim

Member
Joined 2019
To reinforce what DougL is saying, if you have an active crossover at 250 - 300 Hz, and you drive the both the upper and lower sections with 50 W of pink noise, you will achieve the same SPL as if you had driven the entire system with 200 W of pink noise from a single amp.
 
AllenB

AllenB

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Joined 2008
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The speaker itself is a passive component and its load is complex. A crossover can change this, but voltage sources have a certain immunity to the variations.

Besides, the only way to make it a perfect load is to add a passive conjugate, even if your filter is active.
 
Juhazi

Juhazi

Member
Joined 2007
Audio amplifiers are supposed to handle varying impedance, with varying success...

I have used ICEpower 125 and 50ASX2 modules for 6 years now, power on all the time 24/7 no problems and I can get 110dB, but woofers distort heavily. Each board has own transfformer, so it's very easy to make a case for two units. First I had all four in one case, but turning it up blew the house sectional fuse.

Use eBay to search or ICEpower modules, way back then I had to buy 4-5 units stacked, but the price was ok and they are nice to have around for speaker testing and diy design/protots. Cases can be found from recycle bins and eBay too.

For 3-way actives I chose Hypex FA123 and that gives more than enough power too.

Different gain of units is not a problem, your drivers have different efficiency and eq anyway!
 
gadut

gadut

Member
Joined 2008
I jump into active setup - 4 way + subwoofer - because i already have too many amplifiers if i only stick with my passive speaker.

for ease of your mind :
- class d on sub/woofer, no need something fancy like Hypex, use chinese kit but decent quality
- midrange & tweeter deserve a good quality amp, a good gainclone project or class AB/A (many option in this forum) will not break your wallet.

my choice (remember i already have all those amplifier before active setup) :
- class D for subwoofer : behringer nu3000dsp (there are other better amp but a lot more expensive)
- class AB for woofer : aragon2004 (bought 2nd hand item)
- gainclone for midbass : mauropenasa (build it)
- class A for midrange : 3 amps from NP subforum (built it)
- cheap class d for tweeter (only work above 5kHz)

if you want to build same topology for each way, look for Peeceebee on this forum which has high power pcb up to 150W for woofer/midbass and low version 50W for midrange/tweeter

but if you look for commercial brand, you will waste the fun of DIY
 
mtidge

mtidge

Member
Joined 2018
bellarossafabrica.net
First off, thank you for the feed back, I thought this thread had died. Going with less power per driver does solve a few problems, I could use IcePower 50ASX2SE for all drivers. This gets the cost down to around $200.00 USD per side. I have a few questions about IcePower, I have read that they really need an input buffer because of the input impedance. The other thing I would want is a remote trigger, I haven't figured out a good way of doing it yet. Lastly it seems that Hypex NCore is universally preferred over IcePower, but this could be just folks that are chasing perfection that isn't audible.

I have a cheap Dayton/Wondon DSP amp setup, I use it for testing new crossover designs. Nice toy, but does not measure well, 50 Watts at 10% THD just doesn't cut it. The idea of using 4 different 2 channel power amps is not for me, the maximum number of boxes for me would be on DSP and one 8 channel amplifier. It might be nice to target each driver with just the right amplifier but I would prefer class D for all drivers.
 
4

454Casull

Member
Joined 2004
hifijim said:
To reinforce what DougL is saying, if you have an active crossover at 250 - 300 Hz, and you drive the both the upper and lower sections with 50 W of pink noise, you will achieve the same SPL as if you had driven the entire system with 200 W of pink noise from a single amp.
Click to expand...
Only in specific situations. I think the commonly-cited source on this (ESP) also has this to say about it:
Note: It must be explained here that the 3dB effective power increase is the absolute maximum that can be obtained. In most cases it will be less - I have examined sections of music where the power gain was less than 1dB, and it can be reasonably safely assumed that the real gain will lie somewhere between 1-2dB in most cases. The real figure depends a lot on the type of music, the actual crossover frequency, and the peak to average ratio of the two separated signals. Just this topic alone is sufficient for a complete article in its own right.
Click to expand...
BiAmp (Bi-Amplification - Not Quite Magic, But Close) - Part 1

On the other hand, depending on the type of music and the HP/LP points of the crossovers, a given channel may need up to 80% (or more) of the nominal power requirement in order to produce the necessary peaks without clipping. For example, if a mid driver has a sensitivity of 90 dB / 2.83 V, and you want it to play (in concert with the rest of the complement in the active speaker) so that the resulting sound level is 100 dB, the mid driver may take up to 8 W or more, as opposed to the 3-5 W one might expect based on the average music power distribution. So, based on this, a reasonable person would probably size that channel for 10 W (again depending on the HP/LP points).

Music and the Human Ear (see Peak Power chart)
 
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