RTA12 HFM Crossover Resistor values

Crashdot

Hi,

I have a set of Polk RTA12's, which I think have undergone a series of upgrades and changes before I owned them, and I'm not sure that everything matches.

In addition to crossovers which have upgraded good quality components, I believe the drivers were changed, and I changed the tweeters myself. I have two sets of crossovers that had different resistor configurations, and I'm not sure which was correct at this point. What I am trying to determine is what the resistor values were for the different revisions of the RTA12 High Frequency Module which could affect the output of each tweeter that was used.

Unfortunately, the schematics available do not represent all of the parts on the HFM crossover, and are not available for all versions of the RTA12, so I can't compare them vs the tweeter used in each. It would probably be necessary for those that own these types of speakers to examine the resistors used (if any) unless someone has notes on this.

The reason I am asking is that in the current configuration, my receiver is having to boost the high frequencies of the RD0194 tweeters to a very large degree in order to achieve flat frequency response. If the included SL2000's are used, this is true to a lesser extent, and if SL1000s are used, the high frequencies actually have to be reduced because they are so loud. I realize that each of these tweeter models has different frequency response and specific peaks in the earlier ones, but it occurred that they may have different relative output levels such that the various revisions of the RTA12 crossovers may have had corresponding resistance values to adjust their output.

If anyone has any information on the resistors used in each RTA12 crossover and the corresponding tweeters used, I would greatly appreciated it.

Thanks

Joe08867

Which ones do you have? Your question is about the whole line not a specific one.

drumminman

It would help if you post pics of your Xover. Try and take one showing the entire board, including labelling.

Crashdot

Hi,

I'm not sure what these originally started out as, 12B or 12C, but I believe the drivers and tweeters were both changed from the original configuration, and the crossovers have undergone significant changes. I would essentially like to know the appropriate resistor value(s) for each tweeter type.

Crashdot

I don't know if this will help - this is the underside of the board with the schematic overlay - note the R1 has no value listed.

One of the sets of crossovers had no resistor, which is the case in a photo of an early crossover I've seen (included below)

The other crossovers have a 2ohm resistor on R1. This makes me wonder if the resistor, value, or lack thereof is to adjust for each of the three tweeters used. The calibration microphone and my ears are telling me that I don't have the correct resistor installed.

Thanks

pitdogg2

PM Keith(geppy1) send pictures of all your XO's and tell him what drivers you have. He's the KING of the RTA12

Crashdot

I was going to contact geppy1 after I tried to gather some information in case there are forum members that may have different models of the RTA12 series to refer to. From previous discussions on this forum, it seems that at least three different tweeters were used on the RTA12, and three crossovers. I anticipate that the crossovers were not identical, and can find a lot of discussion about the caps, but not much about resistors.

drumminman

It must be an early version as you have fuse instead of a polyswitch, though dating these speakers from the parts used can be tricky.

Mine are definitely 12C's, though they use the fuse instead of the polyswitch, and have the SL1000 tweeter. Geppy 1 may have some better advice, but, barring that, I would buy several different values of resistors. Swap em in, listen and decide which one works best.

I would start with a low value, say around 0.12, and then double it several times if you don't like the effect. Easy to do since the Xover is accessible.

Good luck!

Crashdot

Which resistor, if any, are you using with the SL1000s?

My cabinets and/or crossovers are 12Cs, but it has been suggested that I may not have the original drivers, the tweeters have definitely been changed, and both sets of crossovers modified. I would like to know what resistor goes with the Peerless, SL1000, and SL2000/RD0194 if these changed with each revision.

The above topside photo of the crossover with fuses is not mine, it was listed as an illustration that some do not have any resistor in the R1 position. The first underside photo is one of mine. Here are the tops of my crossvers.

Upgraded crossover in use

Relatively stock crossover for bi-amp testing

Thanks

drumminman

I'll have to look at mine to be sure, but I don't remember any resistors in R1. I do have the 0.75 amp fuse instead of the polyswitch.