slimpikkins
Super Member
The yellow caps when replaced may change the sound of your Infinitys and not always for the better...I believe they are polyester made in Mexico. Most will out live us all before they go bad.
RSIIIA Crossover assistance please.
- Thread starter INeedInfo
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bluescat
Well-Known Member
Not meaning to hijack, but since the IIIB was manufactured after the IIIA would it be safe to say that the IIIB sounded better????? My reasoning is that the driver's for the A&B "SEEM" to be the same, but the crossover is different, and have often wondered about this. Has anyone here A/B'd them and/or tried recapping the IIIA with IIIB caps, and if so, what were the results? Thanks!!
Infidel
New Member
I'm wondering if they were made to be more profitable by 1986 /1987 as opposed to sounding better.
One example being the less expensive to produce cabinets on the later models.
One thing that made me wonder is the cost of the capacitors on the earlier models . 1200uF required where later used 600uF in one position, and actual number of capacitors. I see the early ones and the reference in #41 to plural yellow capacitors - I only have one Mexico 7uF in the late model.
In my searching I find references to models that preceded the RS-IIIa and RS-IIIb using the Watkins woofers using 1200uF in their crossover networks. Maybe Infinity had a stock of them and used them until they ran out - nothing to base this on in fact so I should shut up.
The cap I was referring to in the last post is a different one than the light yellow "Mexico" cap.
It's the bright yellow one that looks like a round one that was squished. It is roughly the size of two AA batteries side by side. 16.5uF 250v. The KSC printed on the cap might refer to King Sunshine - Southeast Asian. I can't find out much about them, but also found Vishay products with KSC part numbers. Both the hand drawn RS-IIIa and HK's messed up version have MM listed as the value of this part! No idea what the MM means!
I was about to change more caps, but will keep it with the two aluminum electrolytic caps.
The Richey Capacitors sales rep was willing to put in an order for replacements, but I would have an unknown wait time and 998 extra capacitors of unusual value.
I honestly can't follow how the circuit is working due to lack of understanding of electronics - especially the inductors being new to me.
I'm having a situation I was discussing on another forum where I'm loosing sound through one channel that matches a rise in heatsink temperature in a well pre-heated class A amp. It was suggested that the Richey blue electrolytic 600uF cap is bad. Sounds awesome at normal listening levels but a heavy bass line or loud rock music is where I'm having the failure.
I'm enquiring here because of the Infinity specific forum section and looking for results from people that had made changes.
Unfortunately I overlooked the message early on about the differences between the IIIa IIIb not matching the HK group misprinting.
One example being the less expensive to produce cabinets on the later models.
One thing that made me wonder is the cost of the capacitors on the earlier models . 1200uF required where later used 600uF in one position, and actual number of capacitors. I see the early ones and the reference in #41 to plural yellow capacitors - I only have one Mexico 7uF in the late model.
In my searching I find references to models that preceded the RS-IIIa and RS-IIIb using the Watkins woofers using 1200uF in their crossover networks. Maybe Infinity had a stock of them and used them until they ran out - nothing to base this on in fact so I should shut up.
The cap I was referring to in the last post is a different one than the light yellow "Mexico" cap.
It's the bright yellow one that looks like a round one that was squished. It is roughly the size of two AA batteries side by side. 16.5uF 250v. The KSC printed on the cap might refer to King Sunshine - Southeast Asian. I can't find out much about them, but also found Vishay products with KSC part numbers. Both the hand drawn RS-IIIa and HK's messed up version have MM listed as the value of this part! No idea what the MM means!
I was about to change more caps, but will keep it with the two aluminum electrolytic caps.
The Richey Capacitors sales rep was willing to put in an order for replacements, but I would have an unknown wait time and 998 extra capacitors of unusual value.
I honestly can't follow how the circuit is working due to lack of understanding of electronics - especially the inductors being new to me.
I'm having a situation I was discussing on another forum where I'm loosing sound through one channel that matches a rise in heatsink temperature in a well pre-heated class A amp. It was suggested that the Richey blue electrolytic 600uF cap is bad. Sounds awesome at normal listening levels but a heavy bass line or loud rock music is where I'm having the failure.
I'm enquiring here because of the Infinity specific forum section and looking for results from people that had made changes.
Unfortunately I overlooked the message early on about the differences between the IIIa IIIb not matching the HK group misprinting.
Last edited:
slimpikkins
Super Member
You mention the models earlier than IIIa/d having Watkins woofers. The original RSIII did not but they DID have what infinity called "a new embodiment of the Watkins principle" using two single coil 8" woofers instead of a dvc woofer as did the RSII what used 10" (non watkins) woofers. This did make a pretty busy, expensive xo to build. The newer rsIIa/b and rsIIIa/b did away with this concept and just wired the woofers in series sharing the same caps and coils.
Jim
Jim
I realize I’m reviving an old thread, but I need help. I have a set of rsIIIa’s that I’m trying to recap as well but am not sure about what seems to be seven 3.83uf caps in parallel. Trying to make a parts list but can anyone give me guidance on these? See pics. Thanks in advance!
Attachments
pauljh
Active Member
I never noticed that before, but looking at the schematics, it is absolutely the case. That’s for pointing it out. And though the RS2a/b used a conventional series wiring of the woofers, they were shipped with an external active contour box that allowed bass extension below the woofer/box resonant frequency.
Seppo
Super Member
In RS-IIIa/b the two woofers are identical and wired in series. They also share the enclosure space. So nothing really specific / special relating to Watkins principle IMO.
In RS-II's the two woofers have different cross-over points (the one at the bottom crosses over at 60 Hz, and the one at the top at 125 Hz). The woofers are also in separate enclosures. The RS-II setup was meant to create "new embodiment of the Infinity / Watkins principle", basically having one of the woofers covering for the other when the latter hit its resonance frequency.
In RS-II's the two woofers have different cross-over points (the one at the bottom crosses over at 60 Hz, and the one at the top at 125 Hz). The woofers are also in separate enclosures. The RS-II setup was meant to create "new embodiment of the Infinity / Watkins principle", basically having one of the woofers covering for the other when the latter hit its resonance frequency.
The yellow caps are higher-grade film caps, not electrolytic caps, so they probably don't need replacement despite their age.
The schematics from the internet shown below have at least one error.
The hand drawn schematic is what are in my RS-IIIa. Hope this helps.
Note :The caps in the bass circuit were increased by a prior owner.
Thanks for the info! On a related note, I recently purchased a Pioneer VSX-LX503 receiver to run my RSIII’s on. I figured the receiver wouldn’t supply quite enough power to really get the subs moving like they can. Are there any recommendations for a 2 channel pre amp to incorporate?
toxcrusadr
Omelette au Fromage
I have not owned these speakers so I will let others report their experience. But in general there are so many receivers and amps, it's hard to recommend one in particular, and there will probably be many that sound good.
The RSIII is rated "4-8 ohms" which means the impedance may dip to 4 ohms somewhere so it is a challenging speaker to drive. The VSX is rated 120 wpc at 8 ohms, 230 wpc at 6 ohms, and there is no rating for 4 ohms listed on their site other than 'yes'. Also the 8 ohm rating is for 20-20kHz and the 6 ohm is for a 1 KHz signal, so it's a bit hinky how they're reporting it, and that's probably how the 6 ohm rating can be almost twice the 8 ohm rating which it would not be if measured under the same conditions.
You do want an amp rated for a 4 ohm load. One way to tell that an amp has a very robust power supply is that its 4 ohm output is as close as possible to twice its 8 ohm output. A 'perfect' amp (in this sense anyway) will be exactly 2x but that is rare and usually expensive.
The other thing to look for is wattage at least as high as what you've got. You'd actually have to go double to hear much of a difference, but OTOH its ability to deliver current may be superior to the VSX even with very similar max wattage ratings.
Usually a multi channel HT receiver has a bunch of compromises in order to fit all the features into the box and be able to drive x number of channels with a power supply that also fits into the box. So two channel is the way to go for an amp for 2-channel listening.
Read up on the RSIII and other Infinities around here and see what people are using for amps.
The RSIII is rated "4-8 ohms" which means the impedance may dip to 4 ohms somewhere so it is a challenging speaker to drive. The VSX is rated 120 wpc at 8 ohms, 230 wpc at 6 ohms, and there is no rating for 4 ohms listed on their site other than 'yes'. Also the 8 ohm rating is for 20-20kHz and the 6 ohm is for a 1 KHz signal, so it's a bit hinky how they're reporting it, and that's probably how the 6 ohm rating can be almost twice the 8 ohm rating which it would not be if measured under the same conditions.
You do want an amp rated for a 4 ohm load. One way to tell that an amp has a very robust power supply is that its 4 ohm output is as close as possible to twice its 8 ohm output. A 'perfect' amp (in this sense anyway) will be exactly 2x but that is rare and usually expensive.
The other thing to look for is wattage at least as high as what you've got. You'd actually have to go double to hear much of a difference, but OTOH its ability to deliver current may be superior to the VSX even with very similar max wattage ratings.
Usually a multi channel HT receiver has a bunch of compromises in order to fit all the features into the box and be able to drive x number of channels with a power supply that also fits into the box. So two channel is the way to go for an amp for 2-channel listening.
Read up on the RSIII and other Infinities around here and see what people are using for amps.
You mean a 2-channel power amp fed from your A/V receiver (not a pre-amp)?
Any decent 2-channel power amp around 100-150 wpc into 8 ohms that doubles output into 4 ohms would work fine (100 wpc @ 8 ohms and 200 wpc @ 4 ohms).
The RS-IIIa/b are not terribly difficult to drive, but they aren't 16 ohm, high-efficiency speakers, either. Your A'V receiver is fairly robust and as long as you don't listen at concert levels you may be fine.
My apologies for not having previously done the basic research to know the difference between preamps and power amps. But I now understand the difference and appreciate your sharing of knowledge, Ross.
Now for perhaps another shoot first ask questions later, uneducated question, has anyone any experience with use of a pro power amp for home av? Particularly I’m wondering about the conversion from unbalanced to balanced connections at the input side of a pro power amp from the av receiver.
toxcrusadr
Omelette au Fromage
I think as long as you use proper adaptor cables it's a cinch.
pauljh
Active Member
I just hooked my JBL UREI 6260 power amps back up. Two of them running in dual-mono driving Kappa 7.1 Series II speakers, bi-amped. Yes, you can use a "pro" amp for home audio. Some folks swear by them.
These particular amps have XLR, terminal strip, and TRS connections. I'm using TRS to RCA adapters and they work just fine. Nearly 40 pounds each and 300 wpc into 4 ohms. They can be had pretty inexpensive if you look around.
