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Old 24th December 2006, 09:06 PM   #11
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Quote:
Originally posted by Eric_B_C
On the wattage, isn't that split between the drivers?

In one tower I have 6 drivers. 4 mid ranges and 2 tweeters. So if your 50watt example was applied to my speaker would I not need 300 watts? 6x50 so that each speaker was given 50 watt?
No. The drivers are arranged in series and parallel and the resultant impedance is 6 ohm. Even a 10 watt amp would probably be enough for "normal" listening levels. It's not till you start building these things you realise how far a few watts go. I'm not suggesting 10 watts is a long term solution though, 50 or 60 watts will probably work very well.

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Old 24th December 2006, 11:26 PM   #12
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This may help. Or it may sound stupid.

Realize what you are trying to do when you listen to music. Are you trying to put the band in your room or are you trying to take your room to the concert.

If you are trying to put a rock band in your room, then all you need is PA quality speakers and a lot of power. But rent the equipment because you will be deaf soon.

On the other hand, if you take your room to the concert, then faithful reproduction (quality) is prime. Power becomes only a number. Any gainclone kit will make you very happy. The quality of the sound will astound you.

What impresses me more than power is how good a sound a system can make even at very low levels. A gainclone will impress you both ways. From a sweet high note on a violin or the thwack of a kick drum and wall shaking bass guitar. This with no signal processing. Just straight from the CD player to the amp. Tone controls are for cheap systems!

May I suggest : here or: here

I have built kits from both sites and point to point LM3886 chips. And am very happy with the results.
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Old 25th December 2006, 02:00 AM   #13
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Thanks!

Low volume high definition is what I am looking for and I am looking also for high volume clarity.

I've seen the evilness that signal processing does I've learned a lot about bass management on multichannel music and now play all my stuff straight through a analog bass manager with zero no other dodads besides the DAC in the player in the way.

For my sub I was looking at a Carver1800 or a EP2500, both very high wattage amps for subs which I still believe you need a lot of power for. I assume I am still better off with one of these because of their cost, roughly $250 USD for approx 600 watt per channel. This is only pertaining to the sub itself.

Well I went and ordered the Chipamp Stereo kit w/ PS, the one on sale for $55.

What else am I going to need? I think the perfect box for the unit, at least on the cheap, is one of the old external USB HD boxes I have laying around.

1. I need something to get power to the unit correct?

2. Input/outputs?

3. Potential meters for the knobs?

4, Best type of solder?

Any other misc stuff I need to pick up?

I'd like to know what else I'll need so I can pick the stuff up this week.

Thanks for all the help...I'm hoping this is going to turn into something pretty interesting.

I'll admit I'm still having a hard time believing the quality of these amps simply because outside of this site, even on the other DIY speaker sites there is very little if any talk of these units.

I'm pretty excited to try this out. Now if I can find out how to turn the iPod into a Line Out instead of a amped output.
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Old 25th December 2006, 09:13 AM   #14
AndrewT is online now AndrewT  Scotland
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Hi,
be quick, buy in some stock of tin/lead (63/37) cored solder in various thicknesses. If you think you may become addicted to this DIY lark then buy in 500gms of each and maybe 1kg of 16g.

If all your speakers are the same sensitivity, let's take an example at 90db/W (/W implies similar impedance), then each speaker needs the same drive voltage to reproduce the recorded signal.
So your 50W into 8r amp can push out about 28Vpk and each speaker is capable of 107db maximum output.
You DO NOT NEED more power into the bass speakers.

If the sensitivities are not matched, which is much more common, then the drive voltage (and power) need to be adjusted to allow each driver to produce the same volume from the same recorded signal (at the appropriate frequency).

A PA bass driver can easily manage 96db/W (and more) and would need one quarter of the power that a 91db mid driver requires.
However a HiFi bass driver that has swapped efficiency for extended bass response could just as easily have a sensitivity of 84db/W and require four times as much power as the 90db mid driver and 16 times the power of the PA driver. Thats's where the misconception comes from. Understand the numbers and don't be misled by the uneducated.
Just to exercise your brain. Tell us what power each driver would need to produce 110dbA from this hypothetical driver array:- bass 84dbW, mid 90db/W, treble 100db/W. Clue you are exceeding half a kW in total (and the "problem" is the 84db bass driver).
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Old 25th December 2006, 10:12 AM   #15
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Sounds like you are well on your way! And yes you will need a transformer. You can get a good toroid at Parts Express. But of course you may want to shop around.

The enclosure is a whole different world. Wide open to the limits of your imagination and budget.

You'll find that the hardware part is more difficult than the actual electronics.

PS My thoughts only: Better to go overboard on the heat sinks!

ENJOY!!! I've yet to hear of anyone regretting building a gainclone.


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Old 25th December 2006, 03:23 PM   #16
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Andrew,

Thanks for the excellent explanation...of not much I understand

I understand the concept but none of the nomenclature means anything to me. I have pretty much zero electrical background and my biggest challenge is finding out how different terms. Like Vpk, and when you say 8r, is r impedence?

Also by PA Driver, your talking sub woofer correct?

I understand your question and know the idea that the values will increase exponentially as efficiency goes down. Is the watt per db linear?

Meaning if 50watt at 8ohms produces 107 db does that mean that it takes 2.14 watts per db?

So the hypothetical speaker at 90db/W efficiency you talk about would take 51.4 watts to run at 110db?

If that is correct, or close at least I'm trying to figure out how I do the math backwards for the subwoofer at 84db/W.

Now the sub/PA in my setup would be a seperate, but the mid and tweeter would be one and they have different power requirements. Is the splitting of the wattage handled in the crossover?

I always thought the crossover handled splitting up the frequencies but I guess now the way its being explained it also handles managing how much wattage goes where.

That leads me to another question if that is true. My towers include 4 mids, 2 tweeters, 1 active sub with its own 300 watt amp, and 2 passive woofers.

If the network manages wattage and frequency is mine a two stage? I have wattage going into the speaker. It has its own internal cross over at 80hz that it feeds to the sub. It also has its own LFE. Since the woofers are passive(they react against the sub) then where does that wattage go? Assuming that the wattage/frequency split in one single function.

I think I know the answer but it will help me understand hearing it from someone else and comparing it to what I think.

Am I getting close?
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Old 26th December 2006, 08:13 AM   #17
AndrewT is online now AndrewT  Scotland
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Hi,
getting closer

db/W is logarithmic not linear. It very roughly follows what our ears/brain do.
db is a RATIO. 1=0db, 10=10db, 100=20db,1000=30db etc.
notice the number of zeros = the first digit of the db ratio.

db ratio =10log[p1/p2], you need a calculator for this.
The power ratio P1/P2 = inv log[db/10], "inv log" is the 10^x key.

If you want 110dbA in the room from a 100db/W driver you need an extra 10db of power. 10db=10times (from above).
So, if 1watt produces 100db then 10watts produces 110db. That's what the sensitive treble driver needs after the crossover.
Now consider the mid driver's power requirement. It manages 90db/W so it needs an extra 20db. that is 100times. So, 100Watts after the crossover will take the mid driver to the same 110db as the treble unit.
The bass driver is just 84db/W. This needs an extra 26db of power. P1/P2 (the power ratio) = inv log [26/10]=inv log (2.6)=398.1 so the bass needs 398W to match the volume level coming from the mid and treble speakers.

You can put about 400W into an actively driven bass and 100W into an actively driven mid and 10W into an actively driven treble and with an appropriate active crossover preceeding the amplifiers, the sound will be balanced . That's a total power from the amps of 508Watts. If the drivers had a passive crossover and the crossover was sending the correct frequencies to each of the speakers AND adjusting the POWER sent to the drivers to match their sensitivities then about a 1kW amp would be required to match the active system for loudness.

Now the revelation.
If all the drivers were the SAME sensitivity and you chose carefully to ensure each was 100db/W (some would be very expensive) then all the drivers would reach the same 110db with just 10W amplifiers on each, a total of just 30Watts, (cf. 598Watts). Passively a 20W amplifier would drive the combined set to about the same volume as the 1kW amp and the cheap drivers.

Just to put that into perspective. Some listeners only choose horn loaded drivers and often these can have sensitivities exceeding 105db/W. that's why they need just 8W of ClassA power to play LOUD.

The BIG message in all this Bass does not need extra power. Less sensitive drivers need extra power.

PA is public address and is often used to identify Disco and similar sound reinforcement duty. It is usually designed to reproduce music and optimised for (low quality) music duty, enabling very sensitive drivers to produce deafening volume in people filled auditoria from just a few tens of kW.
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Old 26th December 2006, 12:26 PM   #18
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Andrew,

Thanks again. It is making more sense now. The array I am looking at is efficient at 90db so 50watt should be way more then enough at your example.

In fact when I was reading some more on the array most people run them with around 50-100 watt. The designer did say they sounded better with 100watt but I don't know why that would be if they are efficient at 50watt, is there an advantage?

We're off to the electronics store in a bit to pick up the rest of the needed pieces and then its just a matter of waiting for the kit to show up.

I plan on testing them on my DIY speakers I have first then my main drivers.

So last question...what is the advantage of doing monoblock at 50 watt and stero at 50 watt per channel. I ordered the stereo unit but if there is an advantage will upgrade it to dual monoblocks.
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Old 26th December 2006, 08:44 PM   #19
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I also found out that my current speakers have an efficiency rating of 92db!

So the unit I'm building from Chipamp, along with a 330va transformer should give me more than enough to drive them at max volume, correct?

I'm really wondering how thats going to compare to the 135watt my Yamaha puts out which was measured in real world at around 117watts actual output.
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Old 26th December 2006, 09:36 PM   #20
AndrewT is online now AndrewT  Scotland
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Hi,
Quote:
db ratio =10log[p1/p2]
there's the formula.
Tell us if you think you will hear a big difference or a little or none at all?
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