Ohm Walsh 2 recap

[jhaan92]

Alright, I've gone beyond my comfort zone and have decided to refurbish a family owned set of Ohm Walsh 2s

These have sat, unused and in boxes, for almost 15 years, as somebody (we don't know who) decided that these poor things could handle the full power of a Carver m-400t Power Amplifier. Needless to say, the spider surround was torn from the cones on both drivers, so they just got sent off to Ohm for repair (John Strohbeen was very accommodating to me, and gave me a nice deal on fixing them - otherwise I wouldn't have been able to do it for a long time.).

However, I do know that they were bought in May 1984, and I know that due to their age, they are in need of a recap. However, I just cannot bring myself to send the cabinets in and spend that much money to get the crossovers replaced - so I have opted to do the work myself.

The crossovers have a total of 4 capacitors in them:

500uF 50v
250uF 50v
375uF 50V
4.7uF 50v

Now, while the first three are for the woofer (I believe, given their high values, and also that they are on the common side of the crossover), the last one is for the crossover to the tweeter. I have decided to stick with generic non-polarized electrolytic capacitors for the first three, as they are not mission critical. Nice benefit is that they are 100v, so they will be less restrictive.

My biggest concern is the 4.7uF cap. I am stuck between Dayton and Jantzen. I have heard good things about both, and when comparing the specs between the two, the tolerance on the Dayton is +/- 1%, whereas the Jantzen is +/-5%. However, how is the Dayton musically? My dad used the Z Caps for a crossover rebuild of his ADS L-400 bookshelf speakers, and they sounded wonderful, but I am somewhat hesitant on the price.

Anybody got any ideas between the two? If the Jantzen caps are musically accurate, they that would be the route I would take. Otherwise, if they are equals, then I would prefer the Dayton's for their close tolerance spec.



-Jason

 

[jhaan92]

Taking apart the crossover board on the Walsh speakers is not for the faint of heart - you have to knock the supports out to get the crossover board out of the cabinet. I tried every other way that I could think of, but they decided to be clever and staple the board down. Also, beware of the ferrite bobbin in the corner - it is held in place with a small chunk of wood, which is not only glued to the cabinet, but also the bobbin. I broke the bottom corner off the bobbin trying to remove it. I would recommend a heat gun (paint stripping) on it's lowest setting to release the hot glue that they used to secure the wood to the cabinet.

The more I dig into these speakers, the less I am impressed with them. I know that it is only the final sound that matters, but in the other cabinet, one of the braces actually fell off on it's own, and several in the other cabinet were just barely hanging on. It looked like they used contact cement to secure the braces to the cabinet walls.



-Jason



PS-I will post pictures to this thread once the battle has been won.

 

[audiomagnate]

Either cap will work fine. Do you actually have them apart? Photos would be great. These are some of the oddest (to be kind) constructed speakers ever mass marketed.

 

[Batch68]

Upgraded my 2's to 2000s a year or so ago, and yes -- its not for the faint of heart. In mine the polyfill used for damping crumbled everytime I touched it & I finally turned the whole thing upside down and literally hammered the old crossover out of the cabinet.

 

[jhaan92]

Yeah, I am going to an R-15 fiberglass fill to replace the old material, as mine is starting to crumble as well. Also, I am going to place it farther down in the cabinet as shown in the original literature from Ohm, rather that right on top as I found it. If I don't like how it sounds, I can always pull it and place it somewhere else in the cabinet.

As for pictures, none yet. I already took one apart with the help of Dad, and so when I take the other one apart, I will take pictures of everything. As for the bracing in my previous posts, Dad came to the conclusion that it isn't contact cement, but rather hot glue...really?!

I have also repaired the grills, which were completely broken and took me a little over an hour to get them positioned correctly for gluing, which I used a Plastic-weld epoxy for a better hold than superglue. I didn't want to replace the grills, as not only are they original, but they are brown, which is a color Ohm no longer makes due to some issue with fading...?

We are also planning on building a set of bases for these speakers as well, which will be permanently mounted to the feet of the Walsh cabinets, and will be finished in black laminate. Dad (and Mom) bought these speakers not too long before they got married (she got them when they split), and he told me that if placed on a carpeted surface, that the bases give the Walsh's a chance to actually get the bottom end frequencies out past the cabinet before being absorbed by the carpeting. In short, they won't sound as tinny. I figure that he has been in this hobby for nearly 40 years, and given that was how he used these speakers, it was an opinion that I could trust.

The bases would also have binding posts attached to them, as I felt that it would make it much easier to move/transport them if I didn't have to unscrew them from the bases every time I wanted to move them to disconnect the speaker wires.

I have found that whoever built these for Ohm certainly cut some corners, and I feel that these speakers were certainly made for a profit, but, as interesting as this is, they sound much nicer than their construction would indicate. Plus, these are a family history item for me, so restoring them is well worth it as far as I am concerned.

I have decided to go with the Jantzen blue caps for the tweeter end of the crossover, as they sounded great in a set of ADS L400 bookshelf speakers, and I guess that I don't really want to stray all too far from what I already know.


Hopefully this will all be over in a month.



-Jason

 

[jhaan92]

These are some of the oddest (to be kind) constructed speakers ever mass marketed.

Indeed. I fully plan on auditioning them against my ADS L710s once I not only get the Walsh's done, but get the 710s restored as well. I think that it will probably take me about a year to get them both back to minty working order.

Also on my plate are a set of all original KLH Model 17's, with the matching turntable/receiver to go with it.



-Jason

 

[Rob41]

You might want to consider building two new crossovers to spec rather than removing the original crossovers at all. Simply leave the original crossovers in place but run your wiring through the new crossovers only. Find a suitable (better) way to mount the new crossovers.

 

[jhaan92]

That thought crossed my mind until I started digging into the cabinet and found one of the strangest looking crossovers I had ever seen. In the end I decided to keep everything as original as I could and just replace the caps, as it is a high possibility that the woofer fires out of phase from the tweeter, given its design.

I plan on starting to dismantle the other cabinet so I will take pictures as I go.



-Jason

 

[jhaan92]

Everyone has been asking for pictures, so here they are:

The Ohm's before I began to take them apart. I mostly took this picture because I had just finished fixing those pesky grills:

This is what one looks like with the can removed. Note the insulation that is literally right below the driver:

This is what the insulation looks like out of the cabinet. I don't really know what it is, but it is going to be replaced with two layers of R-15 placed near the center of the cabinet:

This is what the inside looks like after you remove the insulation. Note that one of the boards has come loose from the cabinet. These are only hot glued onto the cabinet, and will be re-adhered with Loc-tite Power Grabber:

This is a baseball bat.
I chose to use this to knock the braces off (or to destroy the cabinet in a fit of rage if all else fails! ), as it is almost impossible to stick your arm in there to remove the crossover, which is glued to the bottom of the cabinet (also with hot glue):

This is what it looks like with all but one brace removed:

This is the tool that I used to remove the staples that help hold the crossover board in place. Bought it at Sears a while ago, and while it is supposed to be used for removing cotter pins, I have never actually used it for that:

This is a picture that Dad sent to me to illustrate what the bases will look like for the Ohm's. Please note that they will be finished in black laminate to keep up with the look of the Walsh's.

Here is a close up shot.

Does anybody know what kind of capacitor that is wired to the bobbin? It is the red one (technically red, green, white, & red striped one). I can't find a positive pic on the internet, and I don't actually know which way the coding is. The brace that fell down must have hit it and broke the wire off one side.



-Jason

 

[jhaan92]

There are several things to note with this project.

1. Make sure that you find a way to remove the piece of wood that is glued to the cabinet wall that holds the large ferrite bobbin in place, but be careful as not only did they use a large amount of hot glue melt to secure it (and secure it to the bobbin as well), but the bobbin will fracture if you use any sort of impact (IE - hammer blow) on it. I found that out the hard way on the other one.

2. Not only is the crossover board stapled in place, but it is well glued as well, so I would suggest that you gently push up from the outside of the cabinet on the crossover board, above the input terminals, to start to loosen it so that you can carefully pry it out from the inside of the cabinet. Saves so much time that way.

3. There is no 375uf 50v capacitor available that I could find, so simply parallel a 250uf and a 125uf (both 100v) together to create the same value. Also recommended is that all caps have a 100v rating, so that they aren't limiting the speaker/signal path, and even though you won't be increasing the RMS output, or the maximum output, it is thought that there will be less restriction on the signal path.

4. Dad and I agreed that the small cap, which is 4.7uf 50v, is for the high frequency. Don't skimp on that one, as the Walsh 2's normally roll off at 17kHz, so with a higher quality cap with a tighter tolerance should, in theory, bring out a higher level of sonic detail. I don't know if this raises the frequency response (I doubt it), but should make them a little more sonically accurate to one another.

5. The ceramic resistors typically shouldn't need to be replaced, unless they are cracked. I think that I am going to pass on replacing them as it is a mother to take them out and re-do all or the point-to-point soldering work.



-Jason

 

[jhaan92]

Upgraded my 2's to 2000s a year or so ago, and yes -- its not for the faint of heart. In mine the polyfill used for damping crumbled everytime I touched it & I finally turned the whole thing upside down and literally hammered the old crossover out of the cabinet.

You still have any of the old parts left?

 

[jhaan92]

Here is the broken part:

 

[w1jim]

I have a pair of Walsh2 that I purchased new back in the day.
I also found that one of the braces on mine fell out - I used wood glue and a clamp to fix it.
I've considered recapping mine but decided it wasn't worth the risk. I do like the idea of reconstructing the crossover and relocating it (perhaps outside the cabinet).

Do you have a schematic for the crossover?

While these were not made to be repaired they do sound very nice.
I'm about to put mine back into circulation.

 

[jhaan92]

No, I don't have a schematic - Ohm is kinda secretive about stuff like that. Taking them apart isn't a big deal, especially after I found out all of the little things we shouldn't do while taking them apart.

I had also thought about doing an external crossover as well, but I figure that by the time I have to replace the caps again, I will be an old man, almost 60...I'm not too concerned. As for the wood braces, they are easy to remove, and with the tips I posted, so is the crossover.

I just wished I could find a replacement for this capacitor that I have....I'll probably have to talk to John Strohbeen at Ohm tomorrow and see if he'll be able to help me get a replacement.

Near as I can figure, given the color coding, is that it is a 250pf 250v cap, but I am no electronic wizard, so I can't entirely be sure.

I just figured that I would throw a picture of it out there and see if anyone knew anything about it.

 

[doucanoe]

That capacitor looks like a piece of Christmas candy my grandma used to have about the house during the holidays, Jason

To answer your PM inquiry, I've never seen anything like it in my travels I'm afraid. Is there enough lead on the broken off side to get a meter probe on it? It might be interesting to see what kind of readings you get if you have a meter that can read capacitance.

Are you sure about the value of that thing? 250pf isn't but a whisper of a cap.

You want to make sure you parallel the 250uF and 125uF capacitors and not series if you want an additive value result. I wasn't sure what you meant by "chain" so I just thought that I would mention that.

Nifty speakers! I think they will be worth the time invested.

RC

 

[jhaan92]

Well, I tried to get an ohm reading on it, and I slowly pegged a 20,000,000 ohm meter out, so I believe that it is a capacitor rather than a resistor.

I think that it is the protection for the tweeter, as it doesn't take much wattage to get a tweeter to scream - I would think that 15-20 watts would get them pretty damn loud. Plus, it's wired to the bobbin for the tweeter. I don't know if I could bypass it or not, as I don't plan on listening to these speakers at a loud volume, but I also don't know what that would do to the crossover.

Based on what I found, it is based on the old style color coding, and given the color codes, it would be a 250pf, 250v with a 20% tolerance, which would make sense for transient peaks in the music. Problem is trying to find a new one. I am going to call Ohm later today and see what they have to say about it Hopefully they will divulge that information.



-Jason

 

[w1jim]

DON'T bypass it!
You may be able to leave it out. At 250pf it isn't going to pass any audible frequencies.
I'm sure you could get one from Mouser or Digikey to replace it.

 

[jhaan92]

Well, I wasn't able to get help from Ohm, and from my color coding chart I found, it is supposed to be rated 200-300pf, 250v with a 20% tolerance, but in my instrument readings, I got 2.134uf, which would mean that it is a 2.2uf. What the hell?! This is as confusing as trying to untangle a big ball of knotted fishing line!

I wasn't able to get anything out of Digikey, so I will try to look at Mouser and see if anything works.


I should probably get someone like Echowars, MJarve, or Avionic in on this conversation to see if I can't get anything going.

 

[w1jim]

Maybe that first red stripe is actually 2 red stripes?
You can get a 2.2uf poly cap from PE or Erse (or a dozen other audio sources).

 

[ejfud]

I like the Ohm 2's Jason. a real nice speaker to listen too.

I can't help with the cap either, but I'd get those braces clamped good when gluing back in to make them useful. Your old man must have a mess of clamps in that shop of his.

Keep up the good fight. I think you'll enjoy them.