Current!

Brasiliaflyer

So it's been about a month since I started powering my lsi15's with a B&K Av5000. They sound good, but I'm already wondering if they'd do better with more current. The av5000 is 185 watts at 4 ohms and 30 amps max.
So the question is, what kind of current do I need to get those lsi15's to sound amazing? I don't listen at bleeding levels, but I want goose bumps.

SDA1C

There's going to be differing opinions on amps but I would use a Sunfire. Bi-amp and be done with it. All the power you'll need for the lsi15. The little Sunfire is is 200@ 8ohm nearly twice what you need. If that isn't headroom I don.t know what is.

PolkClyde

You will eventually get goose bumps,but it won't stop there. This Hobbie is contagious and addicting . yes they will do better with more current. well,that have been my experience. More current less distortion. My speakers drop down to a 1 ohm load.therefore,I need more current. correct me if I'm wrong veterans polkies.

heiney9

I doubt the Sunfire would be much different than the B & K. He has plenty of power. In fact the B & K is a plenty capable amp for the LSi 15's. I ran a pair to pretty loud levels with my Pass Aleph 30 @ 30wpc.

The OP should look into source components like the pre-amp and cdp and or dac, and cables, etc. He doesn't go into any other detail about his rig or even why he thinks it's lacking.

H9

SDA1C

I was looking at the 185@4 ohm. I am a firm believer in having it and not needing it. IIRC the lsi5 wants 250 @ 4? you could easily out run 185. I believe all speakers run better with more available current. Not that you have to use it to its peak but the more the merrier.

PolkClyde

heiney9 wrote: »

The OP should look into source components like the pre-amp and cdp and or dac, and cables, etc. He doesn't go into any other detail about his rig or even why he thinks it's lacking.

H9

I think he's only lacking the Goose Bumps.I spent a lot of money on my rig and still lack goose bumps...But they have returned today. haha, The Infinity Kappas are singing like a Byrd.

tonyb

Could you use more current ? Wouldn't hurt....do you need it, probably not. I would look at source componants/cableing before jumping the gun on another amp.

Brasiliaflyer

Should have posted more info. Pioneer vsx-1120 and an older Sony cd player. I do plan on upgrading the source, but I've heard that if you start with good fundamentals, you'll save $ in the long run. Figure if I had a more than capable amp, I could be done with that aspect of the system and move on to the next component. Thanks for the advice!

SDA1C

....tube cd would do you wonders friend....

bikezappa

The MUSIC gives you goose bumps not the amplifier.

heiney9

Good fundamentals = source, source, source, source

What are you using an AVR for a pre? Is this an HT? That is another weak link.

In your current senario, the amp is not what's keeping you from goose bumps

H9

Brasiliaflyer

bikezappa wrote: »

The MUSIC gives you goose bumps not the amplifier.

I agree... But I believe equipment allows that to happen.

PolkClyde

tonyb wrote: »

Could you use more current ? Wouldn't hurt....do you need it, probably not. I would look at source componants/cableing before jumping the gun on another amp.

True. I have two mono blocks @575watts and they sound so much better with the Adcom pre Amp GFP 750, DAC, MIT Cables... if you want to talk goose bumps. Just have your priorities in order. Next year this time you will want and possibly buy something new to get those goose bumps you were talking about.

PolkClyde

SDA1C wrote: »

....tube cd would do you wonders friend....

Are Tube DACS Available? I'll do a Google search. I'm in love with DAC

PolkClyde

Lasareath wrote: »

What you want to find out is the peak to peak output current of the two amps.

My new amp I'm getting next week is 96 amps peak to peak.

Is that good or bad "duh" You know your stuff better than I do. 96 seems like a low number.

mhardy6647

SDA1C wrote: »

There's going to be differing opinions on amps but I would use a Sunfire. Bi-amp and be done with it. All the power you'll need for the lsi15. The little Sunfire is is 200@ 8ohm nearly twice what you need. If that isn't headroom I don.t know what is.

If 200 (watts? amps?) is "twice what [the OP] need", it's 3 dB of headroom.

PolkClyde wrote: »

Is that good or bad "duh" You know your stuff better than I do. 96 seems like a low number.

by Ohm's law: P = I^2*R
For R = 8 ohms
P(peak to peak) = 96 amps^2 * 8 ohms = 73,728 watts (peak to peak)

The Rolls-Royce folks might clear their throats quietly and intone "adequate".

SDA1C

mhardy6647 wrote: »

If 200 (watts? amps?) is "twice what [the OP] need", it's 3 dB of headroom.



Ohm's law: P = I^2*R
For R = 8 ohms
P(peak to peak) = 96 amps^2 * 8 ohms = 73,728 watts (peak to peak)

The Rolls-Royce folks might clear their throats quietly and intone "adequate".

Sorry for the confusing post.

The lsi15 is biampable. The op stated he's using a 2x185 @ 4 ohm. The reference was to "amp" = amplifiers. If he uses a Sunfire amp (That I believe only comes in the 5 or more channel config) and he bi-amps his speakers He has 400 watts @ 8 ohms available. Since the lsi15 wants 250 @ 4 ohm I would say 400 @ 8 or 800 @ 4 would be well over twice the wattage that his particular speakers are asking for. When you also factor in the exrta channel that isnt in use as a reserve I would say its "adequate"

Your calculations though holding to the ohms law are dangerously close to PMPO. 73K effn watts.....yea right. Whats he going to do ? Weld with his speaker wires? :rolleyes:

SDA1C

Somebody save us from ourselves.

mhardy6647

Lasareath wrote: »

Well my 1.2TL's are 6 ohms, so 55,296 watts. But I don't think my 20 Amp receptacle will ever provide my amp with 96 amps, so maybe I'll get up to 13,000 watts

The Newest Musical Fidelity that cost 20K puts out 100amps peak to peak!

It's that "instaneous power" thing - it's something of a black hole and has led to all kinds of outrageous claims about power output over the decades, ultimately leading the US Federal Trade Commission to regulate how power claims for home stereo equipment could be reported (the so-called - and inaccurately so - "RMS watts") in 1974.

I don't mean to belittle the importance of dynamic power capability (and for a low impedance load, this means dynamic current capability in the context of driving loudspeakers with music)... but the topic can quickly degenerate into pseudo-technical smoke and mirrors marketing speak...

SDA1C wrote: »

Sorry for the confusing post.

The lsi15 is biampable. The op stated he's using a 2x185 @ 4 ohm. The reference was to "amp" = amplifiers. If he uses a Sunfire amp (That I believe only comes in the 5 or more channel config) and he bi-amps his speakers He has 400 watts @ 8 ohms available. Since the lsi15 wants 250 @ 4 ohm I would say 400 @ 8 or 800 @ 4 would be well over twice the wattage that his particular speakers are asking for. When you also factor in the exrta channel that isnt in use as a reserve I would say its "adequate"

Your calculations though holding to the ohms law are dangerously close to PMPO. 73K effn watts.....yea right. Whats he going to do ? Weld with his speaker wires? :rolleyes:

1) The OP was asking about current, and you didn't specify units when you said "200" so I didn't know if you meant 200 Watts or 200 Amperes.

2) exactly so.

heiney9

Lasareath wrote: »

Well my 1.2TL's are 6 ohms, so 55,296 watts. But I don't think my 20 Amp receptacle will ever provide my amp with 96 amps, so maybe I'll get up to 13,000 watts

The Newest Musical Fidelity that cost 20K puts out 100amps peak to peak!

For what?

D*ck measuring and bragging only.

Quality over quantity and yes, I realize you can have both. Peak to peak is a pretty much useless stat as far as everyday listening.

H9

SDA1C

I'm gonna need 700 volts or 600 amps one or the other or the the whole 73k is moot.

I figured it was the way I said it that caused confusion. The reference was to amplifier not amperes

SDA1C

heiney9 wrote: »

For what?

D*ck measuring and bragging only.

Quality over quantity and yes, I realize you can have both. Peak to peak is a pretty much useless stat as far as everyday listening.

H9

Not to mention when the whole load thing is introduced as lower than originally calculated the watts go up lol.

mhardy6647

SDA1C wrote: »

Not to mention when the whole load thing is introduced as lower than originally calculated the watts go up lol.

They go up, in reality, if and only if the amplifier is capable of delivering the voltage and current into the lower impedance load... thus bringing this thread, I think, pretty much full circle.

nwohlford

mhardy6647 wrote: »

by Ohm's law: P = I^2*R
For R = 8 ohms
P(peak to peak) = 96 amps^2 * 8 ohms = 73,728 watts (peak to peak)

The Rolls-Royce folks might clear their throats quietly and intone "adequate".

I would definitely not assume that the 96 amps is for anywhere close to 8 ohms. I would assume testing conditions would be more like a less than an ohm resistor, everything that could reduce current like fuses bypassed, and a fire extinguisher in-hand.

SDA1C

mhardy6647 wrote: »

They go up, in reality, if and only if the amplifier is capable of delivering the voltage and current into the lower impedance load... thus bringing this thread, I think, pretty much full circle.

Would it be safe to say then that it has completed it's circuit?

tonyb

Brasiliaflyer wrote: »

Should have posted more info. Pioneer vsx-1120 and an older Sony cd player. I do plan on upgrading the source, but I've heard that if you start with good fundamentals, you'll save $ in the long run. Figure if I had a more than capable amp, I could be done with that aspect of the system and move on to the next component. Thanks for the advice!

Think you just answered what needs to be done. You can add a better more powerfull amp if you like, your choice. May give you what your looking for, I dunno, only you can decide that. Normally when one upgrades speakers, the associated source gear/cables do too. Everything matters in the chain as we like to say. So go for the amp first, leave some jingle in the pocket for a better used cdp though.....maybe some cables too. There is no right/wrong way on this, just so long as you experiment with different gear until you find your own personal WOW factor.

As a side note for comparison, my speakers are 4 ohm and more efficient than the LSI's. I drove them at first with a B&k 307 avr. It had 27 amps peek. Your amp is almost the same. I could hear even the 307 start to break up at higher volumes so you may be on the right track for a better amp. But at normal listening levels, the difference between an amp and my avr were slight. Either way, your call, do what you feel comfortable with at first.

One question though, how long did you drive them with just the AVR ?

Brasiliaflyer

Wow, thanks for the discussion.
I know that the whole thing prior to the amp needs upgraded. I'm doing it slowly, and going to the used market due to lack of funds. Figured I would start with the amp since the technology doesn't change fast for them. Thought if I had a good, used amp I could be done with that aspect. I'm new to the lsi series, sold some klipsch rf82's I didn't love. Ran the lsi15's once with the avr, knew immediately they needed more juice.
Patience is a virtue, right? I need to enjoy the journey, as I'll probably never reach the end of the road.
Thanks again for the discussion. Given me something to think about!

mhardy6647

nwohlford wrote: »

I would definitely not assume that the 96 amps is for anywhere close to 8 ohms. I would assume testing conditions would be more like a less than an ohm resistor, everything that could reduce current like fuses bypassed, and a fire extinguisher in-hand.

well, because P=I^2*R, the I (current) term really dominates, so within a reasonable range "R" is more or less irrelevant. More or less...

Thus:
for R = 8 ohm, P(peak) = 73,728 watts
for R = 4 ohm, P(peak) = 36,864 watts
for R = 1 ohm, P(peak) = 9,216 watts
for R = 0.5 ohm, P(peak) = 4,608 watts
for R = 0.1 ohm P(peak) = 912.6 watts

If the amp can truly deliver 96 A into a 0.1 ohm resistive load for, say, 100 msec without self-immolating... that's pretty impressive (at least to me). If it could deliver 96 A into a highly reactive 0.1 ohm load (think of a pair of Polk Audio Cobra Cables!) for 100 msec, and still exist afterwards in a functional state, that'd be danged impressive, I'd opine.

SDA1C wrote: »

Would it be safe to say then that it has completed it's circuit?

very. :-)

shawn474

I have very similar components as you. I jave a pio elite vsx-21txh avr that i am using as a pre, the same b&k av5000 amp, a sony bdp-s1000es blu ray and a sony cdp-cx400 cd player. Tbe cd player just replaced a much older cd player and the difference is night amd day to me. I also changed up my intercomnects to go all kimber kable pbj's instead of the monster ones i jas before, further making a difference. My speakers dont compare to yours as i have the much older ry series bookshelves, but those tweaks definitely improved my system. Not sure if you are looking for improvement across the board or specifically for music or HT. IMHO, the av5000 is plenty of amp across the board for ME, but YMMV.

dudeinaroom

That B&K should be able to give you goose bumps, The preamp and CDP is what is holding you back.

John K.

Brasilia, your question about current is based on a misconception; you can't somehow "give" a speaker more current simply by connecting an amplifier which has a higher current rating from the manufacturer. The amount of current which exists at a moment in time is determined by Ohm's Law, not manufacturer hype. The relevant form of Ohm's Law is: current equals the square root of [power divided by impedance]. For example, your Lsi15s use about 1 watt for a comfortably loud average listening level in the mid 80s of decibels. The current at that point(if the impedance at the frequency happened to actually be 4 ohms) would be the square root of 1/4, i.e., 0.5 ampere. If a brief transient peak occurred which hit about 105dB and required 100 times the power, the current at that instant would be the square root of 100/4, i.e. 5 amperes. Even for 200 watts the answer is just square root of 200/4, i.e., 7.07 amperes.

Don't be taken in by absurd advertising claims relating to conditions that don't exist in the real world of home listening. If such a basic principle of audio technology ever changes it'd be grounds for a possible Nobel Prize in Physics, not just discussions on audio forums.