SDA 2B resto and a Polklore question
JayMX
Posts: 446
Starting into this pair of SDA2b’s today. A friend’s son has been out working a humanitarian mission. Soon to come home and he loves vinyl and old school hifi so I was asked what I could cook up for him. Found a ratty pair of 2B’s in rough shape, stripped em down, now for some maple veneer and new cloth all around. New caps, dynamat, should make a nice rig for him.
Now for the Polklore (not sure if I’ve coined that term, but I think there ought to be a whole sticky thread dedicated to gee whiz Polklore facts... But I digress...) These cabinets have two star-drive screws in the bezels down in the lower right and left hand corners... anyone know why They’re there? They don’t seem to serve any purpose... I’m just curious...
Now for the Polklore (not sure if I’ve coined that term, but I think there ought to be a whole sticky thread dedicated to gee whiz Polklore facts... But I digress...) These cabinets have two star-drive screws in the bezels down in the lower right and left hand corners... anyone know why They’re there? They don’t seem to serve any purpose... I’m just curious...
Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩
Post edited by JayMX on
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All 2B and 1C speaker cabinets started off life as the Studio version. In your case the holes were drilled for the Studio front apron panel before the cabinets were needed to make a standard pair of 2B's. Instead of relaminating the baffle they filled the holes with screws.
Studio version.
Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
@F1nut - interesting. I wondered if that might be the case. Did they screw the apron on from inside?Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩
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I need to edit my original answer in this post. They may have been screwed on from the inside, but I think it's more likely the holes were for dowel alignment pins like on the small bar at the bottom of the CRS. They would definitely be glued regardless.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Cool. Always fun to learn about this stuff. Thanks for the insights @F1nut
I added to the bases, some 1/4 20 threaded inserts for feet or spikes. Got them veneered. Closing up the shop for the day. Next decision, to stain the maple or just clear coat...?
Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩 -
Do you have enough maple veneer left over to try some sample stains out, maybe on some 6" x 6" samples?George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
IMO, just a clear coat on that maple would be boring. If you can use a dye, then clear coat. That will bring it to life like nothing elsePolitical Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
I’ve not attempted to dye wood before. From what I read it’s fairly simple, but I’m sure there are some caveats and gotchas... any pointers for me if I go that route? Suggestions on dye mfgs? Is it better to use an alcohol or water base? This veneer is PSA, will that affect anything? Might be a fun twist to this project, always good to learn a new method.Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩
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That's a tricky question to answer because there's so many different brands and they all are a bit different, so in general...
Aniline water based, I mix my own from powders. You can vary the intensity depending on the ratio of powder to water. They are easier to wipe on because the water doesn't evaporate quickly, but you still have to work quickly. They will raise the grain, so a light scuff sanding is required before a top coat. They are not all that good against the effects of UV.
Aniline alcohol based, again I mix my own from powders. You can vary the intensity depending on the mix. They are best sprayed due to the rapid evaporation. They will not raise the grain. They are better against UV.
SolarLux, premixed alcohol based. Should be sprayed on and work best mixed and sprayed on with lacquer. Pretty good UV protection. The intensity of the color is rather weak compared to other dyes, so multiple applications can be required. Also, likely to require mixing with other colors to obtain a good tone as the color palette is rather plain.
ILVA, alcohol based highly concentrated. This stuff is amazing. Can be used straight, but best cut with alcohol to cut down the intensity. A 10 (alcohol) to 1 (dye) mix will still be vibrant. Absolutely best to spray on either by itself or mixed in the clear coat. Excellent UV protection. Not cheap, but a little goes a long way. The best black dye on the market....I mean black. The dark walnut is exceptional if one desires a true dark brown like found on 400 year old antique furniture. The honey would be a good choice on maple.
None will affect the PSA adhesive.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
"A friend’s son has been out working a humanitarian mission. Soon to come home and he loves vinyl and old school hifi so I was asked what I could cook up for him. "
@JayMX, a short but sweet thread with a kind "mission" of your own."Sometimes you have to look to the past to understand where you are going in the future"Anger is just anger. It isn’t good. It isn’t bad. It just is. What you do with it is what matters.
You can use it to build or to destroy. You just have to make the choice. Jim Butcher
Harry / Marietta GA -
BlueBirdMusic wrote: »a short but sweet thread with a kind "mission" of your own.
Thanks @BlueBirdMusic - it’s always good to have a mission. I do enjoy the ol resto/flip but even better when there’s a little heart in it.
@F1nut - after much experimentation, I successfully dyed them with some honey colored “Early American Maple” TransFast dye. Used alcohol for the suspension. Definitely not a master at the process, but it was a lot of fun trying out something new. They needed to be a bit darker so I topped them with some dark mahogany penetrating stain and wiped it off quick. Finished them with some semigloss spray lacquer. They don’t have a ton of character, but they look a sight better than they did. Next up lots of grille cloth!
Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩 -
Maybe it's your lighting, but I would expect to see a lot more of an orange/amber tone. Anyway, glad you enjoyed trying something new.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
I hit the like button without having to look at them on the big computer. Looks nice.
How thick and wide is the MDF piece that braces between MW's?Don't take experimental gene therapies from known eugenicists. -
Maybe it's your lighting, but I would expect to see a lot more of an orange/amber tone.How thick and wide is the MDF piece that braces between MW's?
It's ~1" thick, spans from the front of the cab to the back and vertically from the bottom of the MW's to the bottom of the tweeter opening. So ~ 10"x10" ? I can measure it exactly needed.
Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩 -
Thanks, just curious. I thought they were 3/4" thick. If making backing rings for them later, Id need to trim 1/2" off each side?Don't take experimental gene therapies from known eugenicists.
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The maple has an interesting irridescence from different angles too.
You'll only get that with dyes due to their transparency. With highly figured woods such as crotch, burl or striped it will appear as though the wood is moving as you move around it. Very cool.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Thanks, just curious. I thought they were 3/4" thick. If making backing rings for them later, Id need to trim 1/2" off each side?
I just measured the brace and it is 3/4” thick. If you were going to make rings, they’d have to be very thin along that side to allow for clearance. There’s about 1/8” of lip and I’d have to remove some glue on this pair to get the ring to lay flush against the bezel.
I’ve enjoyed your metalwork threads. @xschop - I too have thought about building my own rings - a friend of mine owns a very nice fab shop for aftermarket off-road parts (axle stiffening trusses, skid plates, bumpers, you name it...) He has a large capacity CNC laser - I think he can cut stuff up to 1” thick, so lightweight steel sheeting would be a piece of cake to cut, easy to add PEM’s. Just haven’t taken the time to make measurements and call in the favors. Maybe someday. 👍🏻
Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩 -
If you look for pics of Larry's rings you will see that he cut them so that one side is lopped off flat to accommodate for the brace issue with some models.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
And some had to be even more massaged due to crooked or off centered braces....
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And some had to be even more massaged due to crooked or off centered braces....
Yeah, I had to do a little of that, even with strategically placing the straight edges. Excessive glue was also an issue. My Dremel® took care of that. -
And some had to be even more massaged due to crooked or off centered braces....
Looks like the cabinet assembly was done by the same MW assembly workers then.Don't take experimental gene therapies from known eugenicists. -
So. Many. Staples.
Getting close. Should have them done this weekend.
Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩 -
Powergrabbed, dynamatted, reassembled. Think I’ll hold off on the crossovers. They sound very nice as is. Give my friend's son an upgrade to look forward to. Always amazing how much low end comes out of these little drivers and passives. Polk got it right! Fun project!
Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩 -
What's your impression of the change from the Dynamat? In my case I'd have to say that it put the *thwack* sound into the drums.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Nice work. You can also clip the 3 extra factory mount tabs from each MW that aren't being used. I believe they're obstructive.Don't take experimental gene therapies from known eugenicists.
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Gardenstater wrote: »What's your impression of the change from the Dynamat? In my case I'd have to say that it put the *thwack* sound into the drums.
https://youtu.be/-iTJdjrBcuo
Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩 -
Gardenstater wrote: »What's your impression of the change from the Dynamat? In my case I'd have to say that it put the *thwack* sound into the drums.
https://youtu.be/-iTJdjrBcuo
When I did mine, I was surprised by the extra clarity. If you don't mind me asking, how is the son? Teens, 20s, 30s? -
windstriker wrote: »how (old) is the son? Teens, 20s, 30s?
I’m on the lookout now for a ballsy integrated that won’t break the bank but has enough grunt to drive these decently. Considered a Yamaha RS202 but it doesn’t have a phono in... maybe a vintage receiver would be better... His dad gave me a $500 total budget and I’m in about $200 thus far - I picked the speakers up real cheap. I'm not making money on the deal. Also watching for a decent turntable to round the package out. Like @BlueBirdMusic said, it's a fun “mission” for me too. 🙂
Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩 -
Had a little fun testing them on a few different amps tonight. I think the KA-8150 is the winner, but that one will be integrated into my coffin... The M-60 was very analytical and doesn’t have quite the grunt these cabinets need. The KA-7150 sounded good but didn’t have the muscle either. The G-9000 sounded very good, but I’m not ready to part with her and she wouldn’t really fit the budget either... So I will keep experimenting. Good times. Well at least for me. My wife and kids might have gotten annoyed... 😉
Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩 -
Very nice work Jay, the 2B's look like you just purchased them new from a Polk Dealer and set them up. The new owner should be VERY Happy.
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I love threads like this!