KR-9600, searching for clarity

Jeff Miller

Hi, all, Jeff Miller, newb, here. I recently inherited a KR-9600 and four custom-made speakers of roughly 1978 vintage - my Aunt told me they cost $2,000 at the time. Two of the speakers are the size of coffee tables and require two people to lift them. The other two are squares roughly 3X3 feet in size and maybe four inches deep. They have what looks to be curly or tiger maple cases.

When the receiver is set on 'B' (which is driving the big, 'lower' speakers), the sound is clear, powerful and perfect. When you click to A, the smaller, upper speakers work fine, but are, well, muddy and less clear than the gigantic B speakers below them. When you click to 'A+B', the sound becomes noticably less clear than when it's set on B - the sound becomes noticably more 'muddy', as a whole. It's not like 'B' remains clear, but rather that 'B' becomes muddied, as well.

I mentioned this to the guys at the repair shop who did some work on the receiver - they defensively said " 'A+B' vs. 'B' is merely switch-related.' "

So I thought, 'is this decrease in quality because, when you're on 'B', ALL the amp's power is going to B, and when you go to A+B, the power is split? And thus you'd have to turn the amp up to re-achieve that clearness that you got when it was on 'B'?

I tried turning it up to test the theory. It quickly become so loud that the experiment is fruitless, as you'd never want to turn it up that loud in real life. The amp produces power such that '2' (on a scale of one to ten) is loud enough to annoy the neighbors.

To my lay self, it so totally appears that something is amiss when you go to A+B -can anyone provide any insight, surmises, as there is no love at the repair shop? The repair guys (who've been in business since 1962) said 'it all checks out internally.' Thanks in advance to anyone who might be able to shed light.

Jeff

Eric W

Sounds to me the A&B channels are wired in series. Try this- disconnect one set of speakers, then hit A+B again. If the sound mutes, then A + B are wired in series.

Edit, did some searching looks like the 9600 is wired in series. Solution is- run one pair of speakers at a time

inspiredsports

Hi Jeff, Welcome to Club Polk.

Maybe someone here can help get you squared away, but it may be hard as you have an unknown commodity with your custom speakers. Can you remove covers and describe what size/shape the speakers are in the 2 different size cabinets?

There's a short post from back in 2005, but it speaks exactly to what you are experiencing . . .

http://www.audiokarma.org/forums/archive/index.php/t-34275.html

Jeff Miller

Hi, Eric, Thanks for your reply...will try, advise. If they are, indeed, wired in series, what does that mean (presume not good, not optimal, obivously), and what is the remedy? Presume 'wire them so they are not in series'. How does one do that?

lightman1

Hey Jeff. Welcome to the circus. Do you know the maker of the speakers? Some receivers do "split" the power and there are some that don't. If you have the specs on the speakers and receiver, hopefully one the "old salts" might steer you right.
Sounds like a very unique speaker design. (pics?)
Hang around and have fun.

Russ

Jeff Miller

"Can you remove covers and describe what size/shape the speakers are in the 2 different size cabinets?"

inspiredsports: On the big ones, the covers are a brocade fabric with gold flecks in it, they completely wrap the speaker around the front three side. The rear of the speaker is particleboard, appears to be glued in place - no access. Small ones, same fabric, tucked into the underside of the tiger maple outer case. Rear is the same, particle board, glued, no access.

"Hey Jeff. Welcome to the circus. Do you know the maker of the speakers? Some receivers do "split" the power and there are some that don't. If you have the specs on the speakers and receiver, hopefully one the "old salts" might steer you right. Sounds like a very unique speaker design. (pics?)
Hang around and have fun."

Thank you...will take pics. I have the original manual on the KR-9600, it's stock, or appears to be...tech's didn't note anything unusual when they had it in...

Jeff Miller

Have reviewed thread, will test for 'in series' or 'parallel'.

From the thread: "The issue is whether the receiver puts the two pairs of speakers in series or parallel. It's easy to tell...hook up speakers to only the 'A' speaker posts, and put the switch on 'A+B'. Got sound? The speakers are put in parallel when two pair are played at once. No sound? The speakers are in series when A and B are played at once. Now that we know that, we also know that the signal must pass through one set of speakers before it hits the second."

I presume that 'now that we know that' means 'now that we know that the speakers are in series.' If that is correct, what does this mean to me, what's the fix? Is the fix 'all four speakers running out of same channel, A, or B?' Or is the fix 'one set of two speakers running from A (or B, take your pick), then being connected physically with wires to the other two speakers?

beemer

Hello Jeff:

You have a wonderful receiver in the KR-9600. Keep in mind however that this used Darlington power packs as output devices, and these are no longer available.

Regardless of the sound quality, I would advise you to NEVER run more than one pair of speakers at a time with your KR-9600. If the impedance drops, and you inadvertently fry the Darlingtons, you will have a very nice non-repairable doorstop. Use this with care, and it will reward you. It is a GREAT receiver, with one of the best FM sections of any receiver ever made.

Best,

Paul

Jeff Miller

Hi, Beemer,

I've gathered that I scored big with the 9600, and that was confirmed when I researched it. I'm aware of the power supply issue. At the moment, I'm running only two speakers, the massive ones, and it sounds unbelievable.

What causes a sudden drop in impedence? I'm serious when I say the amp will not be turned above 2, virtually ever. If necessary I'll 'coddle it' with two speakers, only, but really want to get her going on the four speakers that my uncle had made.

The amp 'pops' when turned off...I read that in such a case I should turn it to, say, C, when I turn it off, to help protect the power supplies, and have been doing so since I read that. The implication was 'they're aging, treat them gently, this will help'.

Jeff Miller

"did some searching looks like the 9600 is wired in series. Solution is- run one pair of speakers at a time"

Newb dimness occurring, here...'A' and 'B' each support two speakers, for a total of four speakers.

The 'A+B' setting exists to run/power those two pairs, those four speakers.

How can my amp not be able to run those four speakers?

inspiredsports

Impedance (resistance to the flow of electrical current) comes into play.

Low impedance allows lots of current to flow "unrestricted" out of the amplifier. High impedance cause more restriction of current.

When you drive speakers in "series" as the A+B on your receiver is documented to do, the impedances of the 2 speaker groups are ADDED together.

Since we don't know what the impedance characteristics of you custom speakers are, it's hard to come up with a definitive answer. They are probably high impedance speakers and A+B is beyond what the amp is happy driving. More important, they probably have DIFFERENT impedance values so one pair draws currently differently than the other pair.

** Just reread your post #1. Your A's sound worse and your B's sound fine. When A+B ADDS them together, if there is a problem in an A speaker driver/tweeter/crossover component, that PROBLEM gets ADDED to the circuit. I'll bet there's a problem in one of both of the A speakers.

beemer

Jeff Miller wrote: »

Hi, Beemer,

I've gathered that I scored big with the 9600, and that was confirmed when I researched it. I'm aware of the power supply issue. At the moment, I'm running only two speakers, the massive ones, and it sounds unbelievable.

What causes a sudden drop in impedence? I'm serious when I say the amp will not be turned above 2, virtually ever. If necessary I'll 'coddle it' with two speakers, only, but really want to get her going on the four speakers that my uncle had made.

The amp 'pops' when turned off...I read that in such a case I should turn it to, say, C, when I turn it off, to help protect the power supplies, and have been doing so since I read that. The implication was 'they're aging, treat them gently, this will help'.

You have two pair of unknown speakers with no idea of each pairs resistance, ie.....8 ohm, 4 ohm, etc.

When both pair of unknown resistance speakers are played together you have NO IDEA what resistance is being presented to the 9600.

Regardless of volume level, you can and may toast those darlingtons.

You own the receiver, do as you like. However forgive me if you post again when there is no output and I say in reply: "I told you so".

I'm not being harsh, and forgive me if you take it as such, however I have read hundreds of post over the years similar to yours, and the end result is the same, the need of repair of an otherwise working vintage receiver....and in your specific case, no repair as good luck finding the darlingtons. Treat this 9600 right and it has many years left, continue to run two pair of unknown ohmage speakers and trouble lies ahead, as sure as the sun rises in the morning.

Regardless of what you may read from the uninformed, reducing the ohm load on ANY vintage reciever for long periods of time under 4 ohms is a recipe for trouble. None of these were designed to drive a load under 4 ohms, and some though rated for a 4 ohm load, do not handle it well.

Best,

Paul

Jeff Miller

beemer wrote: »

You have two pair of unknown speakers with no idea of each pairs resistance, ie.....8 ohm, 4 ohm, etc.

When both pair of unknown resistance speakers are played together you have NO IDEA what resistance is being presented to the 9600.

Regardless of volume level, you can and may toast those darlingtons.

You own the receiver, do as you like. However forgive me if you post again when there is no output and I say in reply: "I told you so".

I'm not being harsh, and forgive me if you take it as such, however I have read hundreds of post over the years similar to yours, and the end result is the same, the need of repair of an otherwise working vintage receiver.

Regardless of what you may read from the uninformed, reducing the ohm load on ANY vintage reciever for long periods of time under 4 ohms is a recipe for trouble. None of these were designed to drive a load under 4 ohms, and some though rated for a 4 ohm load, do not handle it well.

Best,

Paul

I appreciate the feedback, pun not intended. I'm consulting those who know more than I for the precise reason you mention.

Re: Resistance of the speakers, I can only say that they were spec'd, built and purchased at the same time as the amp by an Electrical Engineer with the intention that they go with the amp, and they were with the amp when I got them. Mentioning that only as data to suggest or imply that the speakers and amp would not be mismatched.

We also know that the four speakers were custom made by the same person at the same time, as a set, which to me would at lfurther suggest or imply that the speakers would not be mismatched in their resistance levels.

Don't worry, I'm not taking any chances until I figure this out.

Back to Eric's discovery, "the 9600 is wired in series. Solution is- run one pair of speakers at a time."

I regret being so ill-informed that my questions might be burdensome to the better-informed, but I'm busy googling 'in series', etc., trying to get a handle on this stuff. We have to get this figured out, as my wife is still clucking her tongue, sort of unable to deal with the 6 foot-long, coffee-table sized speakers in her living room. Kind of like, 'oh you and your crazy old stuff!'

Jeff Miller

inspiredsports wrote: »

Impedance (resistance to the flow of electrical current) comes into play.

Low impedance allows lots of current to flow "unrestricted" out of the amplifier. High impedance cause more restriction of current.

When you drive speakers in "series" as the A+B on your receiver is documented to do, the impedances of the 2 speaker groups are ADDED together.

Since we don't know what the impedance characteristics of you custom speakers are, it's hard to come up with a definitive answer. They are probably high impedance speakers and A+B is beyond what the amp is happy driving. More important, they probably have DIFFERENT impedance values so one pair draws currently differently than the other pair.

** Just reread your post #1. Your A's sound worse and your B's sound fine. When A+B ADDS them together, if there is a problem in an A speaker driver/tweeter/crossover component, that PROBLEM gets ADDED to the circuit. I'll bet there's a problem in one of both of the A speakers.

Ahhh...well, one speaker is gi-freaking-gantic, the other is small. Hmmmm...maybe the big speakers are so bloody big that what you are saying is correct? That maybe Dieter needed even more amp then he had? But the amp seems to drive those massive bad boys effortlessly, tons of sound, at only one on the volume knob. And I've read posts where guys have driven stacks of amps with a 9600.

In terms of trouble-shooting speakers, maybe I'll take the small ones to the repair guys and have them checked out. If they get a clean bill of health then we can reconvene. Know that I won't hook up all four until this is cleared up.

Another clue in the mystery: Dieter added a fuse on the rear of the speakers - his son told me it was 'so they wouldn't blow'. I wonder if he 'blew' the tweeters, previously (or 'blew' some other component in the smaller speakers), and added the fuse so it wouldn't happen again - but didn't fix whatever he blew? Just ruminating.

Thanks, everyone, for involving yourselves in this drama.

SDA SRS 1.2

Take good care of that Kenwood! Mine has performed perfectly since it was new in 1978. There was thread on Audio Karma a good while back where popping was an issue when the 9600 was shut down, but only in the AUX mode. Although it sounded crazy, that issue was due to the "AUX" indicator light being burned out.

inspiredsports

Jeff Miller wrote: »

Ahhh...well, one speaker is gi-freaking-gantic, the other is small. Hmmmm...maybe the big speakers are so bloody big that what you are saying is correct?

Please don't misunderstand and think that resistance = speaker SIZE. It has to do with the configuration of the wire length and materials used within the speaker. A tiny high frequency tweeter can present an electrical load to the amplifier that causes problems, especially if something is blown or shorted out.

Again, didn't you state the smaller "A" speakers sounded "muddy and less clear?"

Using your logic that a pro built the system so all the components would work together, you have to admit it sounds like something might be wrong with the smaller speakers.

You have a good plan to take the smaller units to someone for evaluation. While they are there, ask the tech if he can tell you what their IMPEDANCE VALUE is.

Before you cart those beasts to the shop, have you checked you speaker wires for breaks, open wire, etc. At the ends where they hook to the speakers and amps, are there any stray bits of wire maybe not entirely under their proper mounts and touching each other or metal?

Jeff Miller

inspiredsports wrote: »

Please don't misunderstand and think that resistance = speaker SIZE. It has to do with the configuration of the wire length and materials used within the speaker. A tiny high frequency tweeter can present an electrical load to the amplifier that causes problems, especially if something is blown or shorted out.

Again, didn't you state the smaller "A" speakers sounded "muddy and less clear?"

Using your logic that a pro built the system so all the components would work together, you have to admit it sounds like something might be wrong with the smaller speakers.

You have a good plan to take the smaller units to someone for evaluation. While they are there, ask the tech if he can tell you what their IMPEDANCE VALUE is.

Before you cart those beasts to the shop, have you checked you speaker wires for breaks, open wire, etc. At the ends where they hook to the speakers and amps, are there any stray bits of wire maybe not entirely under their proper mounts and touching each other or metal?

An EE friend of mine said the same - check every connection, make sure they're all perfect.

Now, here's a thought - It is known that channel 'B' is currently powering the big speakers, and is doing so 'perfectly'. I'm gonna switch the wires and make 'B' channel drive the smaller, currently 'muddy' speakers that 'A' is now driving. If they change/become clear, I know I've got an 'A' channel problem. If they remain muddy, voila, I know I have a 'small speaker' problem. I'll double-blind it by connecting the 'clear, good' Big Speakers to A, and see how they sound.

Sorry I involved the Brains Trust prior to performing this basic step. But I've got an extra measure of caution from this dialogue, and that's a good thing.

inspiredsports

Jeff Miller wrote: »

. . . . sorry I involved the Brains trust prior to performing this basic step . . .

No problem. Heck no, this stuff is way more fun than working! And, we don't have to worry about any brains here.