ISO Schematic for LS70 crossover

jakeo25

Hello, links on this forum for the LS70 crossover are broken. Can someone repost?

Also if anyone has the upgrade parts list, this would be helpful.

skrol

Seems to work for me... https://us.v-cdn.net/5021930/uploads/attachments/4/6/7/2/8/18792.pdf

pitdogg2

It will not open for me in 3 different browsers.

Open it and past it if you can.

Clipdat

Attached.

pitdogg2

Thanks
On my phone mozilla, edge and armorfly all said they couldn't.
Thought maybe the op could have similar problems.

jakeo25

Awesome! PDF is easiest opened on PC, Chrome ver 87.0.4280.88 (64 bit). Will update on progress of the upgrade ...

jakeo25

The Polk LS70 is a very similar speaker in size to the LS50, so swapped the terminal block. Found a pair on eBay.

The new terminal block is bigger, so I drilled holes to cut a 3-3/4" height. The width was the same. The opening is done with a jigsaw to fit.



Use the existing mounting holes at the base of speaker cabinet, drill new holes for the top. Then feed the wires through and you grab them from the other side.



The top terminal feeds the tweeter, the bottom terminal feeds the pair of "UW" and "LW" 6.5" speakers. The final product, ready for tests: Mahler, Weather Report, Tangerine Dream, Frank Zappa, among others.



One added design of the LS70 crossover (as compared to the LS50) is it has two cascading low pass chokes, a passband for the UW and a lower passband for the LW.

moodolski

How'd the new crossover set up work out?

jakeo25

So initially I used a Yamaha 5.1 amp in bi-amp mode to drive the HF & LF separately. Generally good, but something always seemed off in the response even after replacing two drivers (speakers).

For a completely unrelated reason, I swapped the Yamaha amp for a NAD C328 and boy what a difference! These speakers never sounded so good! So this was a total success.

I should have remembered how my stepfather's Macintosh amplifier was far superior in reproducing sound. The amp is a key factor!

Sorry for the delay in responding.

pitdogg2

jakeo25 Posts: 7
4:52PM
So initially I used a Yamaha 5.1 amp in bi-amp mode to drive the HF & LF separately. Generally good, but something always seemed off in the response even after replacing two drivers (speakers).

1. No matter what marketing tells you,YOU CANNOT bi-amp with a receiver.
2. The more channels you use on a AVR the less dedicated power you have going to the speakers.
3. You by thinking you were adding more power doing what you did ACTUALLY decreased the available power the receiver had.
4. Look at the receiver power specs, see where it says such and such power @ 2ch at what maybe 1khz not 20hz-20khz most likely. What that means is you only have that rated power AT 2 channels. Most of modern AVR's rated at say 120 per channel are down to 40-50 per channel with 5-6 channels playing.
5. It's easier to blow drivers with not enough current or watts. By hooking the receiver as you did it's easier to clip the signal which will toast something.

F1nut

Worth repeating.

No matter what marketing tells you,YOU CANNOT bi-amp with a receiver.