walsh tweeter design/rebuild

[Jimbo40]

Done deal,repaired and works great.
Found a voice coil, bought 3 different ones all 3 sounded different. the 3rd one was the charm.
I would say the oem is still the best. I went with titanium because that's what the original designers wanted to do but could not afford too.
There design was still the best.
It is amazing how much effect that cone has when attached.
It's not very difficult guy's, you can fix your own.
The OEM has a very high signal range. My new VC is a little wider but still almost exact. none of you would ever tell the difference.
You would have to pull both tweets and run signals back and forth between the 2 to spot it.
And now I have 2 coming from ebay that work also.
First I have 1 and nothing in sight, now I have 4.

 

[haiqu]

Fascinating thread. I have a mind to buy a couple of old Philips AD0160/T8 domes and convert them to Walsh tweeters. One thing that hasn't been answered so far is ... how efficient are they? I remember reading early on in the thread a figure of 78-80dB which is why I stopped building and using ESL speakers, but maybe that referred to full range Walshes.

Anyone care to give me a subjective idea or, better still, actual measurements?

 

[Jimbo40]

Fascinating thread. I have a mind to buy a couple of old Philips AD0160/T8 domes and convert them to Walsh tweeters. One thing that hasn't been answered so far is ... how efficient are they? I remember reading early on in the thread a figure of 78-80dB which is why I stopped building and using ESL speakers, but maybe that referred to full range Walshes.

Anyone care to give me a subjective idea or, better still, actual measurements?

Not sure about efficiency, because you barely hear them.They seem to do something different then make volume. They create an airy presents in the sound that when removed is clearly noticeable and even upsetting. Makes you go @%#$*& and now what @^#%&* or to put it nicely very crabby because you can't just go get a replacement. It's in the cone man.

 

[Nat]

I suspect that omnidirectional tweeters don't measure in the same way that standard tweeters do - most of their output is not direct, yet the reflections do contribute to our perception of tweeter output. It also may be that our ears pick up sounds from a wide range of angles (which is what those reflections would be) and our brains process the input differently than a microphone does.

 

[Jimbo40]

I think that is a correct assumption. The highest frequency takes a different path than the direct path that the rest of the drivers do and it has a different effect on the perception. Im very fond of the sound of the ilInfinity Monitor iiA

 

[haiqu]

I'm very familiar with tweeters that have indirect and complex output due to my work with electrostatics.

Perhaps the question needs rephrasing. What efficiency of bass speaker gives a subjective match to a Walsh tweeter?

 

[Nat]

Electrostatics have output front and back, in a relatively narrow pattern. This makes them not easy to mate with dynamic woofers, though my understanding is that large open baffle woofers, the Hartley being a well known example, can make the job easier.
But omnis don't have that pattern, so may be a different challenge. I had mixed feelings about the omnis I've heard, though the ones I liked best were real omnis and had relatively uniform polar patterns throughout the frequency range, rather than an omni high end coupled with conventional drivers for the mids and lows or just the lows. When there are significant differences in the polar patterns of the drivers, it sounds like there are frequency variations, even if standard (forward) measurements may not reflect this.
Having the other drivers facing upward or down ward makes them somewhat more omnidirectional, and deflectors can have a big effect, but you do end up with an odd looking speaker.

 

[haiqu]

Yeah, I've experimented with mounting speaker drivers facing into the box, my most surprising result being a 4" full range driver that I plugged into a disused coffee can one day when I was in a hurry. With a miniature electrostatic of my own design mounted on top they sounded amazing.

I actually prefer the sound of omnis and open baffles, they lack that beaminess and "I need to keep my head in a vise" problem. A bit more reading seems to show that the Walsh tweeters are very low efficiency though, so I may skip the exercise and just stick with ribbons for now.

 

[webrunner]

I laid my hands on a pair of WTLC's lately. They are not in a good shape but still fair. The woofer surrounds were rotten completely and I replaced and repaired them. The Walsh tweeters are just fine but damping foam disintegrated. It just struck me how these Walshes are built. It seems like an amateur cut the dome and glued an aluminium pipe (not even centered) and glued a handmade cone to the VC. Amazing how low tech and sloppy these are as well as the entire speaker, cabinets and everything. I still have to restore the beaten up cabinets and install everything back. My entire investment will amount to about the equivalent of USD 550 which is not very low, but I went into this because I was intrigued by these speakers. I will post pictures and impressions after I finish the restoration.

 

[Rex81]

I laid my hands on a pair of WTLC's lately. They are not in a good shape but still fair. The woofer surrounds were rotten completely and I replaced and repaired them. The Walsh tweeters are just fine but damping foam disintegrated. It just struck me how these Walshes are built. It seems like an amateur cut the dome and glued an aluminium pipe (not even centered) and glued a handmade cone to the VC. Amazing how low tech and sloppy these are as well as the entire speaker, cabinets and everything. I still have to restore the beaten up cabinets and install everything back. My entire investment will amount to about the equivalent of USD 550 which is not very low, but I went into this because I was intrigued by these speakers. I will post pictures and impressions after I finish the restoration.

Interesting. I have a beautiful pair of original WTLC and I don't find them to be sloppy in build quality at all. Of course the cabinets are made from the 70s pressboard material that was common for that period, but all seams are tight and everything is installed in a professional manner. It seems that your pair was rather mistreated throughout it's life, so I might assume they look a little sloppier than what they did when new and are probably not the best example of the breed. Perhaps someone hacked the tweeters up at some point as well.

Although I agree the Walsh-style tweeter is not particularly high tech. It's not a true Walsh design like the Ohm Model A, F, and G where the voicecoil is actually plucked and sound travels down the cone. Rather, it's a fairly standard tweeter that relies on the cone to simply direct and radiate the sound outward.

If you want to replace the tweeter foam, just scoop out what's left of the deteriorated foam, then head on over to Home Depot and buy a foam shop vac filter for about $5. Place a small can of stain (or whatever) over it and cut out a circle. Then just cut a small hole out for the pole to go through and place it in carefully. Friction should keep it in place on its own.

 

[Jimbo40]

Precisely.
Also there is far more engineering in it beside the average driver that they used. The cone shape, diameter, length, the poly stuffing and foam all play a part of hi frequency sound travel. In relationship to just the air. The sound travels faster through the aluminum foil and radiates out of the cone in a 360 deg dispersion hitting your ears at a different rate from the rest of the sound creating a shimmering and very wonderful sound in the ultra high frequency. I love them for there sound.
The monitor iia sounds phenomenal

 

[tubed]

 

[Jimbo40]

I rest my case.

 

[Bkphoto]

Sound nice...

 

[webrunner]

I finished restoring the WTLC's.
woofers refoamed, cabinets repaired and finished, made a new plinth and a "cage" to protect the walsh's from knocking them off accidentally.
Installed a switch to reverse phase of the rear tweeter (did not decide yet which way is better)
They sound nice. Balanced frequency response and clear sound. They disappear in the room as to the localization of the sound source. It does not seem like the sound comes from the speakers, but from the entire space.
Considering their age and the way the components look, they are quite surprising. They sound good. Very good.

 

[Jimbo40]

I love that Walsh tweeter.
I have the monitor II A with those and I don't care if there made in 1938.
They are fantastic. You try hard to hear the Walsh but you know right away when it's off.
It adds a shimmer to the sound thats not heard in other monitors. And if one breaks, they are repairable.

 

[webrunner]

I agree with you Jimbo40. The Walsh's do add a high frequency component/ambiance and cast an "airy" quality to the sound. All in all, the speakers sound very good and distinct.

 

[James Comer]

I have a pair of Monitor 2A's. I assumed they were like all the other junk speakers from the 70's and 80's Particularly since mine like all the others have trouble with component failure. Apparently I was wrong. I had pyle speakers in the cabinets for decades, and they would play but never had the base response they should. Trying to replace with the same faulty speakers doesn't make sense to me. I put a set of
GRS 12SW-4 12" Poly Cone Subwoofer 4 Ohm speakers from Parts Express in as woofers. I also repaired the crossover which had the pots to the midrange fried with 25 watt rheostats. The dome midrange are a radioshack protected dome mid from the 90's. They had silver paint and Radioshack written on them. I got rid of the silver paint and the Radioshack name. They are to small for the hole and look like crap, but sound okay. I may try other drivers. Why would you want the Walsh Tweeters when they don't hold up and can't be protected? I know, because they look pretty, and they do. Anyway, what are the rest of you using for drivers, and where did you get them. If you know what the originals were and were to get reasonable replacements please post. These sound good but not as good as the original drivers, as I recall. My back speakers are home brew solid oak top and side 3/4 inch plywood back front and bottom.

 

[Rex81]

Monitor IIa are good speakers certainly not in the “junk” class at all, but honestly, you only own the cabinets at this point. It’s going to cost you far more to purchase the right drivers to make them whole than the speakers are worth. I hate to say it, but I’ve had multiple sets of Infinities that weren’t worth saving, so I harvested the valuable parts to sell to others and trashed the rest. Those sets died but others lived on.

A couple of other points: people don’t like the Walsh driver because it’s pretty. I actually think they’re pretty ugly. People like them because they sound unique and wonderful. But as you mention, they’re somewhat fragile and often need refurbishment. There are a handful of people on this site that do that work. If you still have the drivers, that may still be an option.

Too bad you don’t still have the woofers. Those aren’t fault-prone. They should be good for 75 years or more. They probably just needed to have their foam surrounds replaced. Foam degrades over time. It’s designed to be replaced like brake pads. It’s a simple procedure that takes about 20 mins of time and $10 for a new piece of foam.

I personally think that using replacement drivers of any kind is usually a fool’s errand. Speakers like these are carefully designed to make the drivers, cabinet, and crossover work perfectly together. Replace any piece and you’re asking for trouble. They’ll still make sound but it likely won’t be nearly as good as it could be with the original parts. If you were missing a driver or two, I’d say you should go to eBay and try to find the originals and replace them. My honest advice? If you want good speakers, start over and buy complete speakers that haven’t been hacked up. I’ve seen Monitor IIa in original condition for $300.

 

[James Comer]

Rex, thanks for the input. I'm 70 and my hearing cuts out at 10.5 to 11K so I'll somehow muddle through. I'll probably replace the midrange and tweeters with something that looks better, and then hang in there for a pair of Walsh.