probable dumb question

tobybad

can 1B's be converted to 1C's?

heiney9

Have you seen 1C's? How would you fit the extra 2 drivers and extra tweeter in the cabinet properly?

No, you can't turn 2B's into a 1C.

H9

concealer404

He's asking about 1Bs.

Schurkey

Theoretically, yes. You'd wind up with 1C "studio" speakers. So far as I know, the cabinet is the same between the 1B and the 1C Studio, other than the exterior finish.

You'd need to gut the cabinet, leaving only the tweeters and stuffing.

Replace the crossovers with either home-built (using the available schematic) or genuine 1C crosovers; replace the midwoofers using MW6510/6511 units, and I can't remember if the PR is different or not--but that info is listed in another thread here on this forum.

If there are other differences, I don't know about 'em. Differences in driver compliment and schematics are here:
http://www.polkaudio.com/forums/showthread.php?t=55888

Realistically, NO, it's more work and expense than just selling the 1Bs and buying 1Cs.

Don't sell the 1Bs short. They can be easily hot-rodded so as to use the SL3000/RDO 198 tweeter. (not so with the 1Cs that I'm aware of) The only thing they "really" give up to the 1C is the potential for use with non-common-ground amplifiers.

I'm keeping my 1Bs.

heiney9

concealer404 wrote: »

He's asking about 1Bs.

Lol----I see that now . Coffee hasn't kicked in yet.

Since the drivers are different between the 1B and 1C, I'd say no it's not possible. I suppose one could acquire the correct drivers and then rebuild the xover but by the time you do that you can just buy 1C's.

I haven't compared the xovers to see if 1C parts can just be retrofitted. It's possible I suppose but not practical at all.

1C's have a much better cabinet w/better internal bracing.

H9

heiney9

Schurkey wrote: »

The only thing they "really" give up to the 1C is the potential for use with non-common-ground amplifiers.

I disagree. 1B's are certainly no slouch and the ability to use the 198 is appealing, but the 1C's are a better choice if one has the opportunity to choose. The drivers used are a little better and the cabinet is a lot better.

YMMV

H9

heiney9

Also worth mentioning is the simplified xover seems give the 1C's an edge. Anytime you can simplify something with less passive parts, it's usually a win/win.

Schurkey

heiney9 wrote: »

1C's have a much better cabinet w/better internal bracing.H9

Does that include the 1C Studio version? I assumed that the Studio version was just the 1B cabinet (minus the brown vinyl) with the 1C components stuffed into it.

Which, really, did NOT make sense to me; as I'm thinking the internal volume was different between the 1B/1C Studio cabinet and the "regular" 1C cabinet. Therefore the acoustic coupling to the PR would be different. Basically, I don't understand Polk's logic in building the 1C Studio version. 'Course, I don't HAVE to understand to acknowledge that Polk did indeed build the Studio version.

There's also been talk of 1Cs using a double-board crossover vs. 1Cs using a single-board crossover. I've got NO experience here, but if that's true do both crossovers use the same schematic; or are there parts/circuit layout differences between the two types of crossover? Did the Studios get the double-board x-over, while the regular version got the single-board? Or was it a early/late production difference?

heiney9

Schurkey wrote: »

I don't understand Polk's logic in building the 1C Studio version. 'Course, I don't HAVE to understand to acknowledge that Polk did indeed build the Studio version.

There's also been talk of 1Cs using a double-board crossover vs. 1Cs using a single-board crossover. I've got NO experience here, but if that's true do both crossovers use the same schematic; or are there parts/circuit layout differences between the two types of crossover? Did the Studios get the double-board x-over, while the regular version got the single-board? Or was it a early/late production difference?

The 1C Studio was made to reduce the price and it may even have been (I'm speculating) to use up existing 1B cabinets. I don;t have my compendium in front of me but, IIRC all 1C's, studio or standard, used different (MW6511 and MW6510) drivers than the 1B . Those drivers have the side wound voice coils similar to the SRS's of the day.

There was a split board and single board x-over, never really took the time to examine both schematics to see if there are any significant differences. Also early 1C's are not compatible with the AI-1 cable for use with non-common ground amps, but at one time you could contact Ken for a very suitable work around for those early 1C's. [the compendium indicates which serial number are compatible]

So I'd guess early 1C's are more similar to 1B's in appearance but I'm almost positive they had the newer driver's so the rest of the parts were most likely a hodge podge as was typical with Polk of that era using up parts in the parts bin.

H9

dpowell

You might just be better off selling the 1B's, grabbing a pair of 1C's and putting your money into X-over and tweeter upgrades.

Schurkey

heiney9 wrote: »

The 1C Studio was made to reduce the price and it may even have been (I'm speculating) to use up existing 1B cabinets. I don;t have my compendium in front of me but, IIRC all 1C's, studio or standard, used different (MW6511 and MW6510) drivers than the 1B . Those drivers have the side wound voice coils similar to the SRS's of the day.

Agreed on all counts. Makes sense. Therefore, putting 1C drivers and crossovers into 1B cabinets is essentially duplicating the 1C Studio version--unless there's some hidden tweak (possible, but doubtful) to the 1C Studio cabinets.

heiney9 wrote: »

There was a split board and single board x-over, never really took the time to examine both schematics to see if there are any significant differences.

Hypothesis: the two-board version went into the 1C Studio/1B cabinet , and the single-board unit went into the "regular" 1C cabinet (Possible??? Likely???)

heiney9 wrote: »

Also early 1C's are not compatible with the AI-1 cable for use with non-common ground amps, but at one time you could contact Ken for a very suitable work around for those early 1C's. [the compendium indicates which serial number are compatible]

So I'd guess early 1C's are more similar to 1B's in appearance but I'm almost positive they had the newer driver's so the rest of the parts were most likely a hodge podge as was typical with Polk of that era using up parts in the parts bin.
H9

Do the serial numbers relate to studio vs. regular cabinet design? Put another way: Were all the Studio versions built and stockpiled BEFORE all the "regular" versions were built, and therefore the Studios have the low serial numbers, the split circuit boards, and the AI-1 incompatibility???

(I'm sending a pm to H9 so as to not additionally hijack the thread.)

tobybad

Thanks for all the info on the 1B/1C. Did not know the drivers are not the same. I like the 1B's just looking for improvements. Upgraded to 194's, did not know 198's would work in the 1B's. Someday I'll get around to the xovers as my 10's sounded new again after I did them. Can't believe the power the 1B's require compared to the 10's.

heiney9

Schurkey wrote: »

Agreed on all counts. Makes sense. Therefore, putting 1C drivers and crossovers into 1B cabinets is essentially duplicating the 1C Studio version--unless there's some hidden tweak (possible, but doubtful) to the 1C Studio cabinets.


Hypothesis: the two-board version went into the 1C Studio/1B cabinet , and the single-board unit went into the "regular" 1C cabinet (Possible??? Likely???)


Do the serial numbers relate to studio vs. regular cabinet design? Put another way: Were all the Studio versions built and stockpiled BEFORE all the "regular" versions were built, and therefore the Studios have the low serial numbers, the split circuit boards, and the AI-1 incompatibility???

(I'm sending a pm to H9 so as to not additionally hijack the thread.)

I received your PM and when I get some time I'll look in the compendium and respond.

comfortablycurt

heiney9 wrote: »

Have you seen 1C's? How would you fit the extra 2 drivers and extra tweeter in the cabinet properly?

No, you can't turn 2B's into a 1C.

H9

What about 2A's being turned into 1C's. I think I can pull it off...I'm going to call them 1C Jr+'s

JayCee

Hypothesis: the two-board version went into the 1C Studio/1B cabinet , and the single-board unit went into the "regular" 1C cabinet (Possible??? Likely???)

My non-studio 1Cs ("regular") were produced in Sep 87 and I have dual XOs in each speaker. The XOs are tagged 28 Aug 87. Seems they were in the early version of the 1Cs.