Rectilinear III crossover confusion - Should this even work at all?

[Enophile]

This is fantastically interesting!

I have two pair. Given the tweeter array/arrangement, I was thinking these might ‘stack well’ for an inverted pair.

This is on my ‘to do’ list at some point.

A cool mention of these speakers from a show:

Distribution Phonograph: Thöress, Luna Cables, Wattson Audio, Rectilinear | Stereophile.com

As soon as I entered the room hosted by distributor / reseller Distribution Phonographe's room, I thought, "where's all the gear?" There wasn't much around, and of the few items that were around, one was so small as to be nearly imperceptible at first glance.

www.stereophile.com

 

[clayfordsez]

I'm going to install all 8 of the Visatons on mine tomorrow. I did a frequency sweep on the only still functional Peerless tweeter before I pulled everything out. Before I get all the new ones in, I'll run the same sweep on a single Visaton through the same crossover to see how it compares. I'll report back with my findings.

Fascinating thread. Both of my crossovers looked about the same except for totally different colored wires between the two. Here's a photo of one. Seems like these things changed by the day. The striped cap is a 2.0 uF.

3/4 pots were physically broken. 3/4 caps were well outside of spec with one 2 uF being open.

I've got a lead on a few replacement Peerless tweeters, but if the Visatons are close on the frequency response, I'll probably leave them in since it seems Rectilinear IIIs were set up to blow tweeters, and those Peerless ones are somewhat known for fragility in the first place. I'll get the Peerless ones to return to "stock" if I ever want to.

 

[clayfordsez]

Also, I'm literally brand new at this. These are my first project. Glad I'm not the only one who was flummoxed by this crossover

 

[tgmartin]

Glad to hear things are going positive for your project, clayfordsez!

Turns out that, at least on my #2 unit, the TOTAL problem of no tweeters turned out to be corrosion. The male spade terminals on the front baffle board ALL had a thick coating of white dust on top of darker corrosion. I noticed this as I was attempting to measure the DCR of the drivers and my meter probes were being VERY intermittent. I cleaned the lugs up and DeOxit-ized the crap out of 'em. Voile! I measured the caps and found the 60uF read 68uF and the 2uF read ... 2uF! Put this one back together enough to make noise and test proof of concept.

IT LIVES!

Sounds pretty nice now. The pots even function! I'll have to get new caps, glue up some internal bracing, epoxy reinforce the crappy stock particle board pedestals and weatherstrip the baffle. I don't really care about the cosmetics so much. Hope the #1 unit acts as nicely to some care and feeding.

The thing that really sticks out immediately is that Philips midrange. It has an exceptional top end. I can appreciate how the original owner may have not really noticed that the tweets were silent if he was listening to his Lawrence Welk at background levels with the Mid control maxxed out.

I'll take care of these and listen for a while, then, maybe, try out PeteB's suggestion for the crossover mod. I don't want to burn those sweet tweets if I can help it and his mod seems to offer some hope.

YAY!

 

[clayfordsez]

The problem with the tweeter XO is that the 60uF has the DC resistance of the woofer across it, that branch
passes highs but also lows and DC. The 2.5 uF has the midrange inductor and midrange across it so it also
passes lows and DC.

The attached mod gives the tweeters a real second order crossover.
The 2.7 is X ed out but of course is required, you might have to increase the value to get enough tweeter output
since we've removed the leakage across it.
The mid is run wide open on the top end - it also is not very well protected with the "leaky" 60uF feeding it.
I read that people really rave about these so I'm trying to keep the changes to a minimum.
View attachment 3809269

Pete,

I'm going to try this mod. The idea of frying my brand new tweeters (or worse the increasingly rare Peerless ones I'm trying to track down) makes me ill.

I'm brand new to this. Would you mind taking a look at my crossover and telling me what to move and where the new cap goes? I think I get the idea pretty well, but I don't trust my skills very much at all yet. Your expertise is greatly appreciated!

 

[Pete B]

First let me say that if you run your speakers with 25-50W or less and do not play them at party levels the mod is probably not needed.
On the other hand it just feels more "right" to me and it should also lower distortion/stress from the tweeters.
If you play them with any amp at party levels then it IS suggested.

1. Snip out the striped cap leaving long leads if you might be putting it back.
2. Snip the wire going between the pots close to the tweeter pot and reconnect it to the - system input terminal.
3. Add the new cap from the system input + to the wire end (snipped wire) of the tweeter pot.

I'd guess that the pot with the 5W (smaller) resistor is the tweeter pot, might want to check that.
When you snip the wire between the pots the tweeter circuit should be isolated other than ground, might want to check that also.

I'd clean all the spade connectors, and put Deoxit on them and any connections that are not soldered. Let us know what you think.

 

[clayfordsez]

First let me say that if you run your speakers with 25-50W or less and do not play them at party levels the mod is probably not needed.
On the other hand it just feels more "right" to me and it should also lower distortion/stress from the tweeters.
If you play them with any amp at party levels then it IS suggested.

1. Snip out the striped cap leaving long leads if you might be putting it back.
2. Snip the wire going between the pots close to the tweeter pot and reconnect it to the - system input terminal.
3. Add the new cap from the system input + to the wire end of the tweeter pot.

I'd guess that the pot with the 5W resistor is the tweeter pot, might want to check that.
When you snip the wire between the pots the tweeter circuit should be isolated other than ground, might want to check that also.

I'd clean all the spade connectors, and put Deoxit on them and any connections that are not soldered. Let us know what you think.

Super clear instructions! Thanks so much. I actually had both of them put back together to stock, and was just waiting on the Visatons to land, but I think I'll do this mod on one, then test the cap value by ear/REW for the closest match.

The combination of the XO leaking lows to the tweets and the Peerless tweeters being spiderless was not a recipe for longevity.

And yes... I like to get loud! lol

 

[Pete B]

Try comparing them in mono before you do anything to see if anything has drifted way off.
You could try them with the controls full up since that will take the pots out of the equation.
Then with the pots half way or where you like them.
Oh, forgot that I think you only have one working tweeter so, can't do this?

 

[Pete B]

When cone tweeters are not enough:
At Frankenfest 2021, Bi-amped with MiniDSP XO, 400W/ch bass, 140/ch top end.

Thread 'Econo-Rec s Tuned to 28 Hz - Looking for Bass Demo Tracks'

Oct 25, 2021

I finished a pair of these in time for Frankenfest as described in this thread:
https://audiokarma.org/forums/index.php?threads/rectilinear-iii-econowave.812079/

Here they are at the Oct. 23 2021 Frankenfest in West Boylston, MA this past Saturday:
They played bi-amped with a MiniDSP for the crossover since I've not yet designed a passive version.
It was also interesting that in my home I felt that they needed 4dB of boost at 28 Hz for a subjectively
flat response but in the large room it sounded better with the boost removed...

• Pete B

• 

 

[clayfordsez]

Try comparing them in mono before you do anything to see if anything has drifted way off.
You could try them with the controls full up since that will take the pots out of the equation.
Then with the pots half way or where you like them.
Oh, forgot that I think you only have one working tweeter so, can't do this?

Right. I'll have 8 Visatons. But I'll do the mod on one channel, run both in mono and pan back and forth to hear where the cap value differs. I'll also measure with REW to take my ears out of the equation too.

 

[tgmartin]

Please post your detailed findings so the rest of us can gratuitously benefit! Go Man Go!

 

[tgmartin]

P.S. Have you checked "My Weekend Score - KLH Model 105's" in this forum? Obvious clone of these klangfarben lautsprecher. Wonder how close?

 

[Pete B]

Link?

 

[tgmartin]

Link to thread in this Forum:

Thread 'My Weekend Score - KLH Model 105's'

May 17, 2008

I purchased these beauties for $25.00 today, and they have such fine build quality, I am amazed. The sound is spectacular as well. Walnut veneer all around, no exposed MDF or pressboard. I had never seen these before -- does anyone else have the KLH 105's? I'd be interested in your impressions.

I also got a pair of Infinity RS-9 monitors for $20 bucks, and they were stored in the original packaging. Both of the surrounds on the woofs need replacement.

• MaxSeven
• Replies: 18
• Forum: Speakers

 

[tgmartin]

OK! Finally got both of them put together and running.

First impression - They're too big for my house! I see why Duke Ellington would have had these things at home (if that's true). I'm sure his pad was bigger than my dump. If they sounded something like this when they were NEW, what's not to like? These things are really in great functional shape, especially considering one of them left the factory with a bum crossover. I basically just cleaned connections, added the missing 2uF cap on one, tightened up the woofer screws a little and weatherstripped the front baffles.

Guess Grampaw was easy on 'em.

I'll have to make some new grilles eventually. The originals are made out of 2 thicknesses of 1/8" masonite that are just held together by the grille cloth and staples and the whole works suffered warping and fading from their time in the dungeon. Plus the cloth is pretty opaque and thick. All those tweeters with fragile aluminum dust caps need something to help keep stupid human fingers from poking them. So far only one of them has suffered this indignity.

Thanks for taking care of them Grampaw!