running LSI 25`s on separate amps

maico172

I have two Vintage Yamaha M85 power amps and a pair of LSI25`s.Is it possible to use one amp per speaker?? Benefits, downside? I apologize ahead of time if this subject has been covered.....THX all

deucekazoo

It is possible if you can mono the amp? Some stereo amps will not let you run them as a mono block. OR you can use the left channel for the tweeter portion and then the right channel for the mid portion. Just make sure you remove the jumpers on the back speaker binding posts and also you have to run a Y to the RCA connector on the amp so both channel see the same mono signal from your pre-amp. Experiment and see if you like it. If you have the amps, might as well use them.

mikeyb128

Bi wiring or bi amping the lsi25 is a waste. The jumpers supply only a signal to the lower binding posts to run the powered subwoofers (they will not Benefit from the extra power to the bottom posts). I would read the Manual for the wiring options. The recommended method by Polk is leaving jumpers in place and running one pair of wire to each speaker. They will perform their best this way.

deucekazoo

mikeyb128
I see what you are saying, it mentioned that in the manual but then later is also mentions bi-amping. This is kind of confusing. I wonder how it is connected inside.

mikeyb128

I owned the lsi25 for several years, I don't recall seeing that statement in its manual.

The top binding Posts essentially run the top portion of the speaker, and bottom runs the subs, which will only be a line level signal. The statement above (figure 9) would be best used for a passive speaker and not a powered one such as the lsi25.

I've always used a good set of jumpers and a "shotgun" style speaker cable. Saves money, and sounds good.

I've tried several ways of wiring the lsi25 including using lfe to its rear amplifier. The jumpers in my opinion (and polks) is the best. No need to over complicate things.

tonyb

deucekazoo wrote: »

mikeyb128
I see what you are saying, it mentioned that in the manual but then later is also mentions bi-amping. This is kind of confusing. I wonder how it is connected inside.

Probably a generic statement in all their manuals. The LSI 25's are self powered at the bottom with it's own built in amp. To change that topography would require some work, and your warranty would be in the toilet.

On other speakers NOT self powered, then that statement would apply. Real bi-amping requires separate amps and a separate crossover. That statement refers to what is called "passive bi-amping". Not that there's anything wrong with it, many use that same technique with very positive results.

The problem with passive bi-amping, really depends on the speakers. Most speakers, the top portion uses less than 20-30 watts at best. If your using a 200 watt amp for that top portion, 170 watts are wasted just sitting there. It's not available to the rest of the speaker. Generally speaking, the power hungry portions of speakers are the mids and lower bass. Get yourself an amp with a good amount of current and you won't have to worry about passive bi-amping.

mikeyb128

I found the lsi25 manual on line. No where does it mention bi amping, im guessing he might have found the lsi 15 manual by mistake.

K_M

mikeyb128 wrote: »

I found the lsi25 manual on line. No where does it mention bi amping, im guessing he might have found the lsi 15 manual by mistake.

I just found the one I think he found.
And it does mention Bi wiring and Bi amping. (*but says Lsi Series)

http://www.specsserver.com/CACHE/FILE18272.PDF

Maybe a mistake from Polk, hard to say, obviously does not apply to Lsi25

maico172

Thank you guys for taking the time to answer....

maico172

OK kids...New dilemma...The subwoofer amp on the right side speaker smoked, and Polk is quoting me $250.00 plus tax and shipping...Love the speakers , but not $300 worth. Thinking of abandoning the subwoofer amps and running the subs straight off my two Yamaha M85`s...Any thoughts ,???or just shell out the $300

tonyb

maico172 wrote: »

OK kids...New dilemma...The subwoofer amp on the right side speaker smoked, and Polk is quoting me $250.00 plus tax and shipping...Love the speakers , but not $300 worth. Thinking of abandoning the subwoofer amps and running the subs straight off my two Yamaha M85`s...Any thoughts ,???or just shell out the $300

What were you running them on before....when the built in amp went south ? This is why I don't like speakers with built in amps. I'd say shell out the 3 bones, get them fixed and then sell them. Polk is running their half off sale on LISIM's, the 705 should be up your alley....and much easier to drive than the LSI's.

sgmsmg

Stumbled across these guys on eBay that offer various Polk plate amp repair services. They don't list the LSi25 but might be worth contacting them.

http://stores.ebay.com/ElectroNetix

No affiliation but might be an alternative to get the amp repaired.

maico172

running them on 1 Yamaha m85.. Been set unlike that for about 5 years

maico172

contacted electronetix... soon as i get the amp back i may send it to them

maico172

Tony B ...I agree with you ,I don't like the built in amps. The LSI 25 seem to require a s*&tload of power also..