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Old 9th September 2004, 01:01 AM   #1
lazyfly is offline lazyfly  Australia
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Default reg psu q - stupid (novice!)

Hi forum.

Hit me if you think it's required - after this question.

I'm still finding electronics confusing as h*ll

My question then, will a regulated psu assist in driving less efficient speakers? Such as 85dB

Thanks for reading and to any replies in advance
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Old 9th September 2004, 02:03 AM   #2
moe29 is offline moe29  United States
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Check out the Zen Variations to read about regulating PSU. I think
it starts with Version 2 or so. Very educational articles!

You need more output power to drive inefficent speakers.

(gernerally speaking)
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Old 9th September 2004, 08:50 AM   #3
Nuuk is offline Nuuk  United Kingdom
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My advice would be to change your speakers! Pretty dramatic but the GC is such a good amplifier with the 'right' speakers' that it will be your best route to hi-fi bliss!
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
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Old 9th September 2004, 09:45 AM   #4
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I say yes to reg PS WILL HELP.

I regulated a 100VA transformer and it performed better than a
400 VA transformer with no reg on high demand music.

regulated the AC output on small transformer varied with load but the DC after reg did not

Unregulated large transformer AC output was rock steady but the DC at the chip sagged badly.

However the small transformer with regulation had large PS caps and the chipamps had 47ufd next to them

the large transformer setup had 1500 ufd at the chips.

Sonically the regulated system was superior.
Sheldon D
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Old 9th September 2004, 12:32 PM   #5
Join Date: Mar 2003
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Sheldon D, your post is spot on.

lazyfly, a low sensitivity speaker doesn't mean it's hard to drive.
That parameter doesn't indicate that by itself.
If the speaker is nominal 8 ohms and doesn't have big impedance dips across the frequency, it will be an easy load for an amp.
It will just play at a lower volume than a very sensitive speaker.
There are very sensitive speakers that are hard to drive and demand power, and this is the reason.

Answering to your question, definitely, the regulated PSU helps alot with difficult speakers.
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Old 9th September 2004, 02:51 PM   #6
lazyfly is offline lazyfly  Australia
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Well there's a few conflicting answers! The nature of forums I guess

Okay how's this then - I want to drive a pair of LSK kit speakers through a GC. It's for my [10 year old] son so the speakers are nothing fancy but will be quite a step up from the tv! It's mainly for his PS2 and a few movies and a wee bit of music. Perhaps this will inspire him to listen to more music and play a few less games!

I really just want to know if the amp will drive them okay. The volume doesn't have to be terribly loud of course but oscillation (which I don't yet quite understand) is my concern. The amp is using a 25+25V 160VA toroid. Havent got the speakers yet.

Here are the speaker specs:

Nominal (RMS) Power  	50 Watts
Impedance 	        8 Ohms
Frequency Range 	60Hz-20kHz (-3dB)
Sensitivity 	        85dB 1W@1M
Recommended Amplifier 	20W - 80W *
Woofer Material 	Treated coated paper
Woofer Diameter 	104mm
Surround Material 	Low Loss Rubber
Tweeter Material 	Mylar
Dimensions 	        167D*234H*145W mm
Weight 	                2.5 Kg
Wish I knew what defined a ig impedance dip! It looks big but they look like spikes not dips. Ahh the frustration
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Old 9th September 2004, 03:08 PM   #7
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the impedance plot for your speaker is actually quite benign.

there are no dips below the 8 ohm nominal till 20KHz

Amps can get into trouble at low impedance lie 2,3,or even 4 ohms.

The GC should have no trouble, though the sensitivity is low which implies higher wattage from the amplifier, I still say that regulating would give you better performance but if the volume is not high and it is in small room, you may not need it.
Sheldon D
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Old 9th September 2004, 03:24 PM   #8
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lazyfly, those graphs tell me much more than the specs.
Go for it, no problem.
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Old 9th September 2004, 03:38 PM   #9
lazyfly is offline lazyfly  Australia
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Thanks SheldenD. So the dip refers to deviation from the rated nominal impedence - 8 Ohm in this case. That makes a bit of sense now.

That they wont go terribly loud is only a good thing re: sanity If a speaker were 88dB and one 85dB does the 85 need twice the power to run at the same volume level? That's oversimplified I'm sure - or just plain wrong.

Thanks again though everyone. This forum is truly full of excellent folks.

p.s I wrote this a while ago and have been attempting to post it to no avail. Anyway now I've time to say Thankyou carlosfm
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Old 9th September 2004, 04:47 PM   #10
markp is offline markp  United States
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A regulated supply will not make up for low eff. speakers. It will make the amp sound better due to stabilty of the voltages. An unreg powersupply will vary greatly under load and this can change the bias points of the circuit causing all sorts of ugliness, both sonically and electrically. Often a lower powered amp sounds better due to this regulated stabilty even at the point of nearly clipping. I find the most improvement is in the tightness of the bass response(that's where the most power gets used too).
If it sounds good... it is good!
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