Slow but sure RS 2.5 refurb

idadude

Super Member
I'm getting to it as I have time and money to make it happen, but I have gotten started on my 2.5s by sending the woofers off to Bill Watkins to be re-foamed and thoroughly checked out. He should have them already and I guess I'll see what the damage$ are when he gets done. I should know by the weekend if he is not backed up with work.

I had a request to make known what my crossover capacitors checked out at, well here's what I got for the right speaker (starting at the bottom and working my way up):

75uf+ 50uf 100V = 142uf , -0.31 ESR
50uf 100V = 67.1uf, -0.27 ESR
700uf 100V = 761uf, -0.35 ESR
1100uf 100V = 1170uf, -0.33 ESR
75uf + 50UF 100V = 141uf, -0.31 "
700uf 100V = 757uf, -0.34 "
3.83uf 100V = 3.72uf, -0.16 "

Left speaker:

75 + 50uf = 141uf 0.27 ESR
50uf = 60.3uf 0.22 "
700uf = 757uf 0.31 "
1100uf = 1150uf 0.31 "
75 + 50uf = 143uf 0.26 "
700uf = 706uf 0.33 "
3.83uf = 3.77uf 0.21 "


I am seeing that I have a lot of work ahead of me, especially in repairing the broken grill frames, the broken top piece (on one side),and then refinishing the cabinets.

I would like to get some classy grill cloth with a nice diamond pattern in it, but can't seem to find what I'm looking for. Where is a good place to buy good quality sonically transparent grill cloth? I like to make things look different than stock, but I will use stock-looking material if that's all I can find. By the time I get to the grill cloth I may be just wanting to get the speakers finished/completed anyway and will use most anything if I don't find some nice material early in the game.


Larry D.
 
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The caps look fine,which doesn't surprise me. Most of the values between the two sides are amazingly close. Old Philco's from the thirties used a diamond pattern. You might want to ask at the Philco Phorum, although I don't think acoustical transparency is that important for 80 year old radios.
 
That's a better way to put it.....'acoustical transparency'.....that's much more accurate than how I said it. Anyway, I haven't found any of the fancy grill cloth I liked to be very acoustically transparent. Most of it is way too thick and would block, absorb, or reflect some of the music, so I may just go with a nice solid black sheer speaker cloth.

As for the caps, I may just replace the 50, 75, and 3.83uf capacitors with film caps some time after the refurb and leave it at that. I hadn't thought about it before, but I guess I should take the tweeter and midrange pots apart and clean them too. I don't know how many years these 2.5s had been in the former owner's garage and how much heat and moisture they were subjected to. I know that the RSMs I picked up last summer sure needed the pots cleaned. They were nastily oxidized, big time.

I'll try to get some pics up as I go along. I appreciate it when others do that. It helps me understand what they're doing and talking about. I'm not always eloquent enough to have people understand exactly what I'm trying to say, so the pics will help.

Larry D.
 
If I were looking for another pair I would want them with stock crossovers. The pots are already exposed and very high quality. Just work them vigorously back and forth, with or without Deoxit, until the contact area gets shiny. I like the look of mine with their new black grills. The 2.5 is one of the best deals out there in vintage audio IMO.
 
In the end I think I replaced all the grill sides with the cutout section, the material had become so weak that just pushing on it caused breakage.

It was a bit of a pain, I made a template and went ahead and made up 12 sections
for all 6 panels then recovered them in black.
 
As for the grill frames, most of the thin sections of mine are already broken. I'm thinking of cutting all the thin sections out on a table saw and gluing in oak pieces, then trimming those down with a jigsaw, sanding them smooth, painting flat black, and putting on the black grill cloth.

My tough repair will be removing the broken top section and gluing it back together and then filling in the spot where a chunk of the particle board is missing. I'm going to have to remove the EMIMs & EMITs and the entire crossover off the board to get it out and glue it back together. I need it clamped to a flat surface when I glue and clamp back together to make sure it dries flat. Right now its bowed because of the broken top & bottom of the middle section. It must have had a hard fall. That's why I plan to make some feet for these, so that they don't suffer another disastrous crash as this one did. Glad it still works and sounds as good as it does.

No word from Mr. Watkins yet. Here are some pics of the damage.

Larry D.
 

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Dude, that breakage is brutal.
The spines on my back grills look ready to go.
That particle board was bogus stock, too bad MDF wasn't in existence.
Have Fun!

Did I mention the RS 2.5 sound is stellar?
 
Pretty much all RS 2.5 and I would imagine RS 4.5 will need the grill frames
and other areas looked at due to the OEM material aging and becoming
very brittle.

I also had issues after a house move with the bottom curved section of the cabinet separating, in this case it opened up and allowed the internal integrity of the sealed cabinet to be compromised.

A couple of pics of a template and new side member made of plywood
to replace all the 12 sections of the grills.
 

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Yeah, I'm not looking forward to doing the repairs, but it will be so nice to have it fixed and up and playing. The fall broke the whole top front panel loose from the side panels and the metal top piece which has the toggle switch, fuse, and rheostats. All the top screws that hold on that broken panel are loose since the panel is broken there (as the pic shows), but the Gorilla glue I'm using to glue it all back together should make it hold together quite well. I've never had a Gorilla glue repair come apart. Its a little messy, but it holds.

Larry D.

P.S. The screw sticking up is the same one shown in a previous picture where a chunk of the particle board is missing. Not sure what I'm going to do there till I get the panel out. Shouldn't be too difficult, just tedious.

Oh, I forgot to mention that I'm looking forward to stellar sound!
 

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Uh oh....

Well I couldn't sleep last night for some reason, so I thought I'd make some use of the time and I began to take the top section of the 2.5 apart thinking that I may be able to glue it back together without removing the crossover. I ended up with a worse problem than I originally thought I had. There were more broken pieces than what my initial findings could see. Once I got it all loose, it just fell into pieces.

Except for the missing chunk by the large resistor, I should have everything to put it back together. This will be a tedious project. I took a few pics of what I found. Well, I better get back at it before I have to go to work.

Larry D.
 

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What frequency was the ESR readings you have taken at? The meter I use only does readings at 100khz, and the reading I got from my 4.5's caps were far lower, except one. All the 150mfd caps in my 4.5's were .02 ESR except one which was .04 ESR. The speaker with the one "high" esr was significantly down in spl and pink noise sounded a lot softer. I replaced all 150's but started on the speaker that was low in spl and soft sounding first. When finished, it matched spl's within half a db with the other, and pink noise sounded the same. When I did the second speaker, all the 150mfd caps measured .02 ESR, replaced them anyway.
 
I do not know what frequency is used to get the ESR reading. Once the glue dries on the particle board top piece, then I can get to the cart behind it which has the manual for my Sencore LC-101. I may be able to answer you then

Bill Watkins phoned me today to let me know that the speakers were done. He was a very helpful and made the whole experience a good one.

When I got home from work today I took the clamps off the two chips that I glued back on (they had pulled off onto the black side rail), so I cut away the excess glue, rasped the edges down and sanded them smooth. Now you can't even tell they were chipped out.

Being encouraged with those good results, I decided to go all out and Gorilla glue the top and bottom back together leaving the crossover intact.. I'd either get it back together or screw it up so that I would have to cut another top panel. With Gorilla glue there is a small window to get everything assembled and in place before it all starts to foam up and become a potential mess.

It all actually went very well. I was surprised to see that everything went back together so straightly. I used wax paper to keep the ever-seeping Gorilla goo away from places I did not want it to go.

So, things are moving along at a rather brisk pace instead of 'slow but sure'. I included a few pics to visually 'splain' my ramblings.

Larry D.
 

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Nice progress, i think the reference frequency for measuring esr is 100khtz...not positive though....edit>>i just tried to find where I read that and can't. Maybe someone else will chim in.
Jim
 
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Nice to see another pair of 2.5s being restored. You do realize that they can produce stellar sound, don't you? :D

The damaged frame looks like a nightmare, but you seem to be doing a good job of repairing it well and quickly. I think your idea of adding "feet" to prevent the speakers from falling over is good. If you search the archives here, someone has done this and posted picks before. You can even make the feet pivot-able, so that they can fold out of the way for transport.

The grill frames on those are ALL brittle and prone to breakage by now. I suspect the adhesive used to glue together all the little "particles" in the particle board simply dries out over time, causing the board to lose integrity. With my first "beater" pair of 2.5s, all the grill frames had serious damage. The second pair, in near-mint condition, had no damage, but one of the frames cracked in one spot when the seller was simply wrapping protective "saran wrap" stuff around the speakers in preparation for moving them. These speakers were never abused in the least, but clearly age had weakened their frames, too. I like the idea of plywood, or even solid wood or good-quality MDF for replacements.

As for the grill cloth itself, the modern "speaker cloth" is usually only made in four colors: black, white, a light beige/tan shade, and a darker, chocolatey-brown. Patterned cloths used on speakers up until the 1960s was usually much too heavy for use with high-resolution drivers like EMITs and EMIMs. The easy way to test cloth is to hold it up in front of your face with one hand on the other side, and try blowing through it at your hand. If you can feel your breath hitting your hand (almost as if there was no cloth there at all), then the cloth should be sufficiently acoustically transparent. If you really have your heart set on a patterned cloth, you CAN silkscreen a pattern on to the regular thin speaker cloth. Use a relatively thin ink or stain, not a heavy paint, and it should remain sufficiently transparent.

Be aware that the capacitors Infinity used in the crossovers for these speakers were not typical ones; they were made to handle very high current. Most caps of similar capacitance and voltage ratings may NOT work as well. You could try grouping several smaller-value caps in parallel, if you need to replace any caps. This would make them a little better able to handle the current demands.

Good luck with the rest of your restoration. I look forward to following the progress.
:lurk:
 
Great results!

I removed all the clamps and cut/scraped off all the excess glue today and the results were very pleasing. Only on the backside of the top of the panel was there a slight unevenness. The front of the top piece and the entire bottom are square and straight, which was my goal. That was a major hurdle that's behind me now.

Had some really boomy cabinets on a large pair of Klipsch speakers once, which sounded like a drum when you slapped the sides of them. I braced them so that after I was finished you could slap the sides and only hear your hand hitting the cabinet's surface. I was getting the 'drum' effect with the bottom section of the 2.5s, that's with the poly fill still in there. Think I will install a few small oak braces in these till there's no more 'drum' sound. (Actually I'm kinda sadistic and just like to slap my speakers around.....)

I included some pics of the repaired top piece and one of the clamps I used which does look similar to a caulking gun. I better get back at it.....

Larry D.
 

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A little farther along....

I am not sure if I had a manual for my Sencore cap checker, but I do have a quick reference guide and I found I had not fully calibrated it when I got it and did not set the ESR correctly. What should have been reading zero was reading -0.38. I will have to re-check all the caps, but I already planned to un-solder them all to make better mechanical contact of all the wires to the terminals and re-solder with Cardas Quad Eutectic. A lot of the factory solder joints are lame and the signal has to pass through a small glob of solder instead of just sealing and ensuring an already metal to metal contact. There are some loose windings on some of the inductors, so I may apply a little clear silicone caulk to the outer windings to keep out any microphonics.

I will have to seal the speaker binding post plate to the cabinet because when I slapped the cabinet, it also buzzed. I'd like to upgrade the posts too, but that may wait till later.

I pulled out all the poly fill and un-hooked the wires from the speaker posts and pulled the top section off the bass cabinet. Now I can do some bracing, then some sanding and re-finishing.

What would you recommend for a finish? I plan to use a couple coats of Minwax Honey Oak colored stain and after that sets up, then rub in some Early American and a reddish brown Minwax stain which will not make it darker, but will bring out the woodgrain nicely. I used that same process on the oak in my pantry and it turned out beautiful.

I used a polyurethane finish in my pantry.....what would you recommend for the 2.5s? Is there a wipe-on type that's recommended? Once the stain sets in and dries, you then wipe off the excess. An oil will not soak in after the stain seals the wood. A clear satin poly might keep the wood & veneers from any moisture damage and it does look good. I'm leaning that way, but I'm also listening to suggestions.

That's all for tonight. As things progress, I'll post.

Larry D.
 
Nice progress, many infinity owners leave the finish alone and put Howards feed n wax on them. If they are in rough shape the Howards restore a finish in golden oak works well. My RSII's were badly sun bleached from sitting in a sunny living room for thirdy years. Used those two products and they look great. You can re apply the feed and wax once every 6 months or so. If the cabinets are really dry it may take two or three treatments two bring back their luster at first.

You most be a gemstone guy. That facetron machine is very cool. I had a machine shop teacher years ago that faceted gemstones. Always thought it would be fun to learn.
Jim
 
What little finish that's still on them is peeling all over, plus there are a few nasty looking little gouges that are shallow enough to be sanded out so these are getting a good smoothing over with a sanding block before finishing. I will have a little time for them tomorrow and even less Sunday, otherwise I have no spare time until next Monday. Progress may be slow till then.

Yeah, the Facetron is a nice machine and is probably the simplest to use. I've taught a few people how to facet a gemstone and it is as simple as baking cookies. If you can follow the directions in a cookbook, then you can facet a gorgeous gem. My first stone took me many hours to complete, then over the years I got to be able to totally cut and polish a very accurate round brilliant in 30 minutes. That's the top and bottom totally finished with extra facets. I've only had a few people take me up on the free lessons I make available. With my help a first stone takes around 4 hours to do. I've been getting beautiful garnets out of the mountains locally and that makes it fun to cut something you found.

Back to the Infinitys........I will see if I can find the Howard's locally. Thanks.

Larry D.
 
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