LS's (Bi-amping or external amp)?

[bilal]

Hi,

I'm new to this forum, and after reading some of the replies on the thread I decided it may be a good idea to post my question here. I do want to say that I'm not to savvy as far as electronics are concerned.

So here is my situation. I recently upgraded to LSi15's after thinking about them for a long time (12 months to be exact). Here is my current setup

Amp: HK AVR 247, (http://manuals.harman.com/HK/Owner%2...om%20lores.pdf)
speakers: Pair of LSi15's
Sub: Cambridge P300HD

When I plugged these in, I didnt get the output that i was looking for. The manual has the following configuration for this amp:

50 Watts x 7, seven channels driven at full power at 8 ohms,
20Hz – 20kHz, <0.07% THD (surround modes), 350 watts total
• 65 Watts x 2, two channels driven at full power at 8 ohms,
20Hz – 20kHz, <0.07% THD (surround off mode), 130 watts total

While reading other posts, I discovered that I could use the multiroom/SB (Remote Speakers) option on the amp for lower frequencies for my LSi's.(i think its called bi-wiring or bi-amping) Is this a safe option, some people have suggested that if you under power your speakers you could damage them and the amp?

There also has a connection for a pre-amp at the back. While this is something I could invest in, I cant look at spending more $200 max at this point.

do you think I should power the speakers with the bi-wiring option? or is that a big no no.

[kawizx9r]

External amp.

Your receiver is not meant to play 4ohm speakers. If you turn it up to high-levels, you'll risk damaging both your receiver and speakers.

An external amp will almost always be a step up from a receivers amp section (unless you've got a high-end receiver), but to really make those LSi's shine you'll need to spend a good amount of coin for a high-current amp. Also keep in mind, your speakers (or any for that matter) are way more prone to being damaged from being underpowered as opposed to overpowered.

-Freddy

[Serendipity]

If you turn it up to high-levels, you'll risk damaging both your receiver and speakers.

+1

Most receivers will go into protect mode if the load is too great or the unit is clipping.

[Bernal]

http://www.polkaudio.com/forums/showthread.php?t=89779

[cfrizz]

Get a separate amplifier of at least 200wpc @ 8ohms. The more power you can give them the better they will sound. Don't bother with bi-amping.

Amps to look at are Parasound, Outlaw, Emotiva, Sunfire, B & K, Nad, Adcom, Rotel.

[bilal]

guys, thanks for all the responses,

Im am stuck between a NAD( 2600A)and an ADCOM GFA-555.

Here some of the specs listed on both

NAD:
Continuous power [ min RMS per channel 20Hz - 20kHz less than rated distortion into 8 ohms ]:
-::- 150W RMS x 2
-::- Rated distortion [ THD, 20Hz - 20kHz ] 0.03%
-::- Clipping Power 200W : Dynamic headroom +4dB
-::- IHF Dynamic Power x 2 at 8 ohms: 400W 4 ohms 600W 2ohms 800W;
-::- RIAA response accuracy : 0.5dB
-::- Damping Factor [8 ohms, 50Hz]: > 120
-::- Slew Factor > 50 -::- Slew Rate > 35V / sec
-::- Input impedance R = 20kohms, C = 820 pF
-::- Input sensitivity [ 1W out / rated power ]: 90mV / 1.1V -::- Voltage gain 32 x [ 30dB ]
-::- Signal to Noise Ratio [ 1W / 150W, A-weighted ]: 100 / 122dB

Bridged Monophonic MODE :
Continuous power [ min RMS per channel 20Hz - 20kHz less than rated distortion ]:
-::- 8 ohms 1200W RMS
-::- 4 ohms 1600W : Dynamic headroom +5dB


AND ADCOM
# Output Power: 200W into 8 ohms (23dBW);
# 325W into 4 ohms (22.1dBW),
# all continuous power, 20Hz-20kHz, with 0.09% THD.
# Input impedance: 22k ohms.
# Sensitivity: 130mV.

which one would you think would be better with the LSi15's and how much do you think is a reasonable price for either one... Thanks much

[kawizx9r]

I'd say the 555, can be had for about $300 unless its the MKII which is often a lil more like $350.

[bilal]

thanks, I just posted a question to the seller asking him if its MKII or not.

[bilal]

guys one last question, I am also considering getting my hands on a B&K ST-202+... Does anyone know how this amp sounds? Is it any better than ADCOM 555 or 5500? I would think the price range would be the same for both.

[bilal]

also the seller got back and said the 555 is not an MKII version.

[kawizx9r]

Can't say anything about the B&K, but as far as the 555 goes offer him $285. You can go a little higher but hey, we're all trying to save an honest buck here aren't we? :)

-Freddy

[dorokusai]

The B&K ST-202 is a wonderful amplifier. I'd say it sounds better than the Adcom and is nicely built.

[bilal]

guys there is a GFA 7500 5 channel amp on ebay. My question is can the amp power my front speakers and my sub woofer. or do i need to get a different amp for that.

the output options at the back of the GFA 7500 are:

Front R:
Front L:
Center:
Surround R:
Surround L:

can the woofer be plugged into remaining slots besides the Front ones. If so I will go after this, if not I will purchase just the two channel one.

Thanks.

[tonyb]

I would be carefull buying anything from e-bay, the B&K option seems to be the good one for now. If your sub,as most do,has it's own amplifier built in,then no need for an external one. If not,and it's a passive sub,then you would look for a monoblock amp for it,not run it off a 5 channel amp. You could do it but results may not be up to snuff. Keep the volume down on those speakers untill you get an amp,that receiver is nowhere near what is needed to power them. DON'T forget the cables to hook up your amp too.