In What Year Would A SDA Early Model 1c Be Made?

notified

Hi I was wondering in what year the early version of the 1c was made [the model that looks like the 1b]Assuming nothing has been changed would the date stamp on the tweeter give a actual representation of the year the speaker was made? I was hoping this info would save me from breaking the original apx, 26 year old seal time has made between the M.F and Cabinet in a effort to determine which model I have. Also.aside from using larry's rings would there be any down side to adding 4 more screw holes around the mf rim to apply a more even pressure to the mounting flange?

Dennis Gardner

The model you speak of is the 1C Studio Models. I don't think that they were any different time frame from the standard 1Cs. You should be able to get close to the date if the drivers are original.

I wouldn't try to add screws to the mids. I would look at adding Hurricane nuts if you choose to go it yourself without Larry's rings. parts-express.com/Search.aspx?keyword=hurricane%20nuts&sitesearch=true

pitdogg2

Do you know if tweeter was ever switched? Chances are you do not unless you're the original owner which it sounds like you're not. Polk is well know for using up old stock most date are when the drivers were made not when speakers were assembled. Now in most cases the builder would put there initials on the passive when they built the speaker...not all the time but I have seen enough to speculate that it could be close.

DO NOT DRILL NEW HOLES IN DRIVER ......

There is no need they seal just fine the way they were built. Now if you desire better get the rings or hurricane nuts and amerflex for a new gasket. This is tried and proven and will not damage the driver. Many try to OVER tighten and warp the basket badly.

notified

I was pondering the use of the hurricane nuts or wood intended heli coils but don't know if they'd be much of a benefit torque wise as long as the 8 screw holes are in good condition.perhaps a 4 and 4 combination just to aid in the possible loosing of the screws? Was also thinking about making a gasket out of relatively thin gauged sheet rubber and securing it to the wood to provide a surface for the spk flange to slightly sink into when tightened to prevent air escaping from around the wood and the flange.Anyway just spit balling some ideas in contrast to the cost and involvement of the ring clamp plan.Also in response to the studio 1c [in black models] being the early model 1C.I inquired as Westguy's business site shows the 1b/early1c both in the simulated wood finish and the black models being designated as a separate studio 1c model

notified

Thanks pitdog I was obviously typing while you were posting! So its definite then gonna have to disturb that seal to find out what model I got,I;m hopping it's the early 1c so I can have the option of mono blocks with the iso trans.but I think that's a slim hope.On the other front, with the baskets being of a thin casting its more than likely to get warped from the spacing of the screws and idiots over tightening,and while the rings do eliminate that concern,But from a cost saving point of view using 8 points to secure it whether it be screws or bolts should provide as much if not more clamping force. And when slowly tightened down in a methodical criss cross torque pattern should eliminate the possibility of warping,I assumed that this wasn't done at the factory as they either deemed it unnecessary or it provided a cost savings in time and material. Oh by the way about the tweeter I did say in the first post "assuming nothings been changed" Not that it matters and I'm the 2nd owner 1st being a older gentleman that was selling as he was getting along in years and was moving into a condo,And again i was just posting to see if there would be any obvious downside that I;m not seeing in regards do trying that method [ PS please don't say a hole in the speaker] as I'm fairly adapt at drilling a hole. lol

Schurkey

If you're going to add screw holes:
1. Be sure to trim the rubber around the new holes to match the rubber around the original holes on the driver frame. Tightening a screw partially onto the rubber is a great way to ruin the surround.
2. Heli-Coils are a poor way to reinforce the cabinet threads. I have absolutely no idea how you'd cut machine-screw threads into MDF/chipboard to screw the Heli-Coil into. Thus the recommendation to use a different style of metal thread insert--the Hurricane nuts.



Far as I know, the 1C Studio was only made in BLACK vinyl, while the 1B was done in brown. If there were any 1C Studios in brown, I'd think they were very scarce.

Pull a midwoofer and find out for sure.

notified

Many thanks for that advice Schurkey,Had that covered my plan was to make a template out of cig,package cardboard to mimic the position of the original screws in relation to the upturned edge of the mf,Find the center between the screws then with a new 1/16 drill bit or similar mark the hole and trim back the surround with a xacto knife,then again use the template to mark and then drill the hole.stepping up the bit sizes till usable with the fastener.Looked up the heli coils and they have them purpose made for wood with a outside screw thread to screw them in using a tool [see you tube] I have never used them or a hurricane nut but i assumed that the inside used a machine screw or bolt [Don't know which insert type would be better in this application] Thanks for the studio update however that wasn't the issue as all studio models come in black named for the fact that they don't need the extra esthetic cost of a furniture finish when used in the studio/ Please read above if its of interest to know what my question was about.Thanks for your interest and your time

Malbec

Refer to the table on page 31 of this link.

http://www.vr3mods.com/uploads/SDA_Handbook_2011_Rev3.pdf

Check the serial numbers of your speakers with what's listed for the 1c's to see if they fall within the range for the 1c's. This will indicate if they are compatible with the AI-1 transformer.

Schurkey

ALL 1Cs are compatible with the isolation transformer, although SOME (early production) need another foot of wire inside each cabinet and a different plug-in connector on each cabinet if the original Polk AI-1 transformer assembly is to be used. The difficult part is finding the proper connector body, as I have the impression that they've been discontinued.

If the isolation transformer is an aftermarket "home-built" deal, there's an infinite number of options for connectors on the speaker cabinets.

notified

Hi many thanks and much appreciation for that Malbec. I had it book marked prior but didn't take the time to give the whole thing a closer read,its quite comprehensive makes me ashamed that I procrastinated and posted about the dented tweeter question [excellent read on tweeters makes me want to push up my rdo purchase.] I'll definitely consult it before posting questions!! And if accepting answers! BTW do you think my mf mounting idea is dafted as the ring thing,as good of a fix as it is still seems like a unneeded extra expense to me in both time and money

Malbec

That's a lot of extra work for what possibly is no gain. Personally, I would feel like I'd be bastardizing the drivers by drilling 4 more holes. Even with heli coils installed you still run the risk of pulling threads if overtightened. The hurricane nuts eliminate that problem. I've seen heli coils fail time and time again in aluminum castings because some knucklehead has to use a cheater pipe on his wrench to make sure the bolt is tight. The "reconstituted wood" used for the cabinets doesn't hold up well to the loosening and tightening of the screws.

Schurkey
I'm inclined to agree with you on all transitional 1c's being compatible with the AI-1. But there's enough SDA **** children out there that makes we wary of that.
There was a work around that eliminated the need to open up the cabinet to add a wire from the socket to the negative binding post.

Malbec

ok..... so I needed to say ba$terd children??

notified

Thanks for your opinion ,If I do decide to go the 8 point route hurricane nuts will definitely be the fastener of choice Although in researching some in the carpentry camp did prefer the screw in heli coil. siting their resistance to pullout.But even if that's valid the hurricane is easier to install and even if I was using the rings I don't think I'd feel comfortable exerting that much force to tighten it down.And in my case scenario without the use of a over-sized washer over tightening would cause the flange to dimple inwards under too much torque Gave some thought to the possibility of the alteration devaluing the speakers but while their average value holds fairly steady I don't think their market value will increase at all in the near distant future,Anyway I don't plan on addressing it till at least this fall even though in comparison to other posters leak tests mine must be far from airtight as when I push in on the PR the MW's follow at the same rate [no hang time at all when PR is released]Again my thanks to you for taking the time to share your observations and opinion, Its been very much appreciated in which ever route I come to choose.

littlewoodboats

The only time I have sucessfully used heli coils in wood are for blind holes in hard woods. For MDF or particle board a coil would be my last choice. If distorting the driver flange is an issue with the four screws your gasket material is most likely to thick. The factory gasket material was quite thin so did not present any issues.

notified

thanks for your response littlewood As I stated Previously! are you aware that they do make heil coils explicitly designed for use in particular wood applications [with a wood screw in type exterior to resist pull out?] although they may not be practically applied in this application as i haven't looked into the recommendations for mdf and at the time of my posting was only contemplating retaining options.As for the mf flange distortion please take the time to read the prior posts for a more complete comprehension as to what was being discussed.Also it appears I had the leak test wrong, Apparently when the PR is pushed in and held in that position the mf's after extending outwards. should slowly sink back down in apx 2-3 sec.Which I suppose leaves mine within specs as my other two sets of factory original Polk's exhibit the same results

littlewoodboats

Having built custom wood boats for going on 35 years I am familiar with the various methods of putting fastners into wood. Good luck

RandyCroissant

The hurricane nuts worked really good for me. I would advise against charting unknown waters on this one. The front mounted heli coil may pull up the area around the insert and destroy the seal, best to stay with the rear mounted inserts.

Nightfall

I'd only use hurricane nuts or Larry's rings, I definitely wouldn't drill into the speaker baskets but that's just one noobs opinion, what do I know? Good luck!

notified

SOLD on the hurricane's!! Just brought up the other thinking being a screw in it might be superior.Perhaps later in the year if I find the nerve and or stupidity to implement my idea [and if small enough inside dia. hurricane's are available] I'll try it on my 7's first and see how the push test goes As I imagine the majority of the escaping air is at the mf.Anyway if its a fail I could always JB up the 4 holes and cover them with the ring thing.or just add 4 more mounting points to the rings.Thanks again for providing me the soundboard its much appreciated

westmassguy

Pay particular attention to the recommended drill size for the Hurricane nuts. Do not deviate.
I use three different drill bits in succession, to prevent blowing out the back side of the particle board, or splitting it. The holes are very close to the edge of the openings.

RandyCroissant

Yep what Dave said plus make sure you drill straight down. Best to lay the cabinet on its back on a rug of some sort.

littlewoodboats

When chasing air leaks do not overlook the cabinet itself.

notified

Just wanted to extend my many many thanks for the tips and considerate photos I found them very informative and when/if I get over my continued procrastination issues I'll most definitely exercise them in practical practice!