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This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
It is a major undertaking to get at my big stereo system, lots of very heavy equipment in a very small space, plus a lot of nice, neat short wires which are commendable for appearance, but makes moving anything something Houdini couldn’t do in his prime!
Here’s my problem, my McIntosh ML-2 left speaker plays at 25% the volume of the right. The effected speakers sounds OK, just low volume. On the same system the Linn Isobaric speakers are normal.
Speaker reverse on the pre-amp does nothing, so it isn’t the 500 watt McIntosh amp.
So simple question, could a partially shorted out speaker connection cause a dramatic volume drop? The speaker connections on the McIntosh pre-amp are unique vice-like connections that grab raw wire. Primitive, but it works.
I ask this question only because everything is so tight that we are talking at least 45 minutes just to get at the back of the pre-amp and any miss-step could send 600 pounds of equipment crashing down on my Beograms 4000 and 8002.
If a short could cause this volume drop it is well worth the effort, but if not, you guys will have saved me one heck of a lot of trouble for nothing.
The enclosed picture is from our first house here in Victoria, but give an idea of what I am talking about.
Thanks.
Jeff
Beogram 4000, Beogram 4002, Beogram 4004, Beogram 8000, Beogram 8002, Beogram 1602. Beogram 4500 CD player, B&O CDX player, Beocord 4500, Beocord 5000 T4716, Beocord 5000 T4716, Beocord 5000 T4716, Beocord 8004, Beocord 9000, Beomaster 1000, Beomaster 1600, Beomaster 2400.2, Beomaster 2400.2, Beomaster 4400, Beomaster 4500, Beolab 5000, Beomaster 5000, BeoCenter 9000. BeoSound Century, S-45.2, S-45.2, S-75, S-75, M-75, M-100, MC 120.2 speakers; B&O Illuminated Sign (with crown & red logo). B&O grey & black Illuminated Sign, B&O black Plexiglas dealer sign, B&O ash tray, B&O (Orrefors) dealer award vase, B&O Beotime Clock. Navy blue B&O baseball cap, B&O T-shirt X2, B&O black ball point pen, B&O Retail Management Binder
Not sure I completely understand the setup...are both spkrs, the McIntoshes and Linns both driven by the same amp? Does the wiring go from the amp to the preamp which then serves as a speaker switcher?
One way to check for a short is to disconnect the wires at the speaker end and slap an ohmmeter on them. That'd let you diagnose a short at the preamp spkr connections without pulling the whole shebang apart.
Cool setup by the way! Don't envy you crawling on the floor for the open reel though!
I'm afraid I'm recovering from the BeoVirus.
Assuming that's a real doggie and not a stuffed one, has he been chewing on the cables?
Jeff: Not sure I completely understand the setup...are both spkrs, the McIntoshes and Linns both driven by the same amp? Does the wiring go from the amp to the preamp which then serves as a speaker switcher? One way to check for a short is to disconnect the wires at the speaker end and slap an ohmmeter on them. That'd let you diagnose a short at the preamp spkr connections without pulling the whole shebang apart. Cool setup by the way! Don't envy you crawling on the floor for the open reel though!
Hi Jeff,
Yes both speakers are driven by the McIntosh 2255 and the speaker selection is via the McIntosh C-27 Pre-amp.
Envy me? You haven’t seen the present, attractive but claustrophobically close arrangement. I could give you details, but you probably wouldn’t believe me.
The set-up you see is ancient; the present has tables with Beograms surrounding it, not to mention the odd S 75 speaker.
The ONLY reason for this question is, is it worth my while to pull all this stuff apart to check the pre-amp speaker connection.
If you saw it, you’d understand…..
MediaBobNY: Assuming that's a real doggie and not a stuffed one, has he been chewing on the cables?
The doggie ain’t real, definitely stuffed…. But friendly!
Oh believe me Jeff, I truly understand the nightmare pulling it apart would be. In my last house I had a custom stereo cabinet similar to what you show, only more horizontally laid out. I hated it when I had to go into it and repair anything.
Id still try the ohmmeter approach, and I'd do it with the preamp switched to the Linns. If you read anything but infinity or completely open on the side that's weak that would be a sure indication of a wiring short.
Since you're using a transformer coupled McIntosh amp it should drive that partial short forever without complaint, with a direct coupled amp of lesser robustness you'd know if there was a short pretty quickly when the amp grenaded.
Jeff: Oh believe me Jeff, I truly understand the nightmare pulling it apart would be. In my last house I had a custom stereo cabinet similar to what you show, only more horizontally laid out. I hated it when I had to go into it and repair anything. Id still try the ohmmeter approach, and I'd do it with the preamp switched to the Linns. If you read anything but infinity or completely open on the side that's weak that would be a sure indication of a wiring short. Since you're using a transformer coupled McIntosh amp it should drive that partial short forever without complaint, with a direct coupled amp of lesser robustness you'd know if there was a short pretty quickly when the amp grenaded.
As I have owned these McIntosh ML-2 speakers since new I have a good deal of confidence that the problem is not them, but rather something to do with either a connection or a partial short.
The partial short comes to mind because I recently replaced all the blubs in my McIntosh MR-78 tuner in addition to replacing the on/off button on the C-27 pre-amp….. you talk about an absolute nightmare. OMG! Each time requires moving the Beogram 8002 and 4000 and carefully turning this 600 pound colossus to gain access to the back. Once everything is unwired the equipment comes out the front.
In regard to the MR-78 first I had to take it apart (one deserves a medal for that alone) to find out which bulbs need replacement, then put it back together awaiting parts from McIntosh Laboratories. The parts arrived, but due to a communication deficiency half of the parts/bulbs were incorrect.
Put the MR-78 back together waiting for more parts. Then with the correct parts in hand, out of laziness decided to not change one working bulb and have a spare bulb, put it all back together (another medal please) and the not changed bulb failed. Open it up again…..
From there it is not that hard to imagine that I messed up on a speaker connection.
All the above is made vastly more complicated because I am running a McIntosh MI-3 oscilloscope which has to be wired in-line using the TAPE input/output lines reserved for a Beocord 9000.
I still don’t have it quite right as if I don’t used the FIXED port the volume adjustments make the picture larger or smaller, which is undesirable. However using the FIXED port renders which ever TAPE port used visually useless, in this case I have chosen to be able to monitor the Tandberg 9000X reel-to-reel rather than the Beocord 9000.
If you are not confused now, you never will be. On second thought, Jeff if this didn’t confuse you, perhaps you should come by and get this thing wired correctly.
You are of course correct in saying that a partial short like what I believe I have here would not phase the McIntosh 2255 in the least, a fact that the factory is rather proud of, and trumpets it at every possible opportunity.
I can see there is no escaping the inevitable; I gotta get in there and rummage around.
I'd still test it with a multimeter first. Select the linns to get the wiring disconnected from the amp, in this way both sets of speaker wires to the Mac speakers should be open at the preamp end. Pull the wires at the speakers and measure the resistance, if there's no short it should read an open circuit, if you read anything else theres a short. Plus you can easily compare the readings for the two sides, the good spkr and bad. I agree there's nothing to point at the MLs as the troublemaker.
I am still very envious of your oscilloscope!
Jeff: I'd still test it with a multimeter first. Select the linns to get the wiring disconnected from the amp, in this way both sets of speaker wires to the Mac speakers should be open at the preamp end. Pull the wires at the speakers and measure the resistance, if there's no short it should read an open circuit, if you read anything else theres a short. Plus you can easily compare the readings for the two sides, the good spkr and bad. I agree there's nothing to point at the MLs as the troublemaker. I am still very envious of your oscilloscope!
Well it is not a connection issue and it is not the wire, which I replaced, to no effect. That is to say there is no short at either end.
With the Linn’s turned off and the mighty McIntosh going into slight clipping protection the right speaker is blasting away, while the left speaker is all working, specifically the woofers are moving plus the mid-range and tweeters sound normal, or they same as the right speaker. The difference is much less bass response and less volume.
Being completely unscientific about this (not trying to measure speakers in motion, the left woofer under heavy load moved 3/4 “ to 1” while the right speaker moves 2” to 3” which moves a whole lot more air than the left.
This is déjà vu all over again as with my damn MC 120.2 speakers only I don’t have the specs for these ML-2 speakers and am not entirely sure where I might find them.
Worse I am most likely too inexperienced with testing resistors, capacitors, etc. to be able to achieve much on my own. What I am saying is I probably need more hand-holding than people have the time for.
If there is a simple test and someone could tell me HOW to test, I’ll certainly do it. I have a Fluke tester but haven’t used it in several years. If there is such a good Samaritan out there I will need to be told everything: “Touch the negative wire to the “X” side of the resistor and the positive to the “Y” side and if you get .005 or more you have a problem. With that type of direction, I can do this. If this is too much trouble, believe me guys, I really understand!
P.S. Your envy of my oscilloscope is much appreciated. Supposedly Florida dealers were allowed three for the year and I got one. I made have fallen for a clever salesman’s tricks, but I never saw another one outside the dealer showroom, so they are pretty rare. I looked at the MI-4 when it came out, but it was in the new model mode and didn’t match my other equipment at the time. I traded everything in, in 1978 so it would have matched, but that is only in hindsight.
Have you tried swapping the wires to the left and right speakers to see if it's really the speaker? Or something else? I'd also try connecting the speakers directly to the amp and see what happens, it's possible the switch in the preamp that selects speakers has an issue, maybe it's barely making contact on one side?
For info on the speakers try contacting Roger Russell. Email or PM me if you don't still have his address, feel free to mention me to him as a reference. I'm pretty sure he can get you info on the speakers, since he designed them.
As you get into it I'll help you however I can. On forum or email.
This is very good of you and most appreciated.
The McIntosh C-27 pre-amp was rebuilt by the factory along with the amplifier in 2008. Aside from the failed on/off switch which gave me such headaches, I rather doubt it is the pre-amp. Never sure of course, but not on the top of my possibilities list.
It was suggested to me that there maybe a bad solder point on the cross-over so I will check that tomorrow.
It really “appears” to me that the mid-range section and tweeter section are both performing correctly, just the woofers that have reduced capacity. Added to that the sound quality is fine, just not enough of it….. I don’t know enough about speakers, or electronics for that matter to know what all this means.
One step at a time.
Thanks again for your help!
Before I tore the speaker apart I'd swap speaker wires between speakers to see if it stayed with the same speaker. Then if it did I'd tear into the speaker. If it stayed with the wire, meaning the other speaker did it, then I would wire the speakers directly to the amp and see if it was still a problem. If not its the preamp.
Have you swapped speaker wires left to right? Or even from the Linns to the Macs? Results?
Jeff: Before I tore the speaker apart I'd swap speaker wires between speakers to see if it stayed with the same speaker. Then if it did I'd tear into the speaker. If it stayed with the wire, meaning the other speaker did it, then I would wire the speakers directly to the amp and see if it was still a problem. If not its the preamp. Have you swapped speaker wires left to right? Or even from the Linns to the Macs? Results?
I switched speakers wires to no effect, so tried going in from the front. No deal. Then opened up the back and found what looks like a pristine and flawless crossover network.
Threw in the towel and took the crossover to the shop that re-foamed my ML 120.2 speakers.
His response was not encouraging, but we’ll see where this leads.
It was a real crash and burn.
I took the crossover network to the shop and they wanted a photo of all the wires connected, which I had, in order to re-wire. The tech didn’t wait for the photo and replaced a capacitor from the mid-range section. Never mind, it is the woofers that are the problem.
Everything else checked out within specs.
So the tech, a pleasant but elderly man wanted to see the woofers. I took them in and it was sheer pandemonium. No place to put anything, stuff falling on the floor, and the poor guy repeating the same tests, one 30 times. (I very wise person once told me doing the same thing over and over and expecting a different result is the height of stupidity.) And so it was.
It didn’t help that the shop owner was all but determined to show the wire going into the speaker was frail…… basically trying to break it and say, “You see, here is your problem.” But the wire refused to break and was pronounced OK.
Another bad shop experience and I have nothing but an invoice to show for it.
Sorry to hear about the frustrating repair place experience. All too common sadly.
Interesting xovr. Have you measured resistance of the woofers? Maybe a connection, one of those push on terminals, was oxidized and became really resistive? Clean them up and put the speaker back together and see if that solves it is one thing to try.
Would like a schematic of the speaker and crossover. Will see if I can find one.
Which ML-2 speakers do you have? ML-2C or 2M? Can you post a pic of the speakers and grills?
Check out the following page. It has info on speakers and specific troubleshooting and diagnostics, from McIntosh.
http://www.roger-russell.com/drivers.htm#servicenotes
Have you checked the fuses? Also the xovr you show doesn't look like the 2C, is yours the 2M?
Take a look at the test steps, they are good ones.
Jeff: Sorry to hear about the frustrating repair place experience. All too common sadly. Interesting xovr. Have you measured resistance of the woofers? Maybe a connection, one of those push on terminals, was oxidized and became really resistive? Clean them up and put the speaker back together and see if that solves it is one thing to try. Would like a schematic of the speaker and crossover. Will see if I can find one.
The shop, sadly incompetent as it was, did measure resistance, among a great many other things, with incredible repetition.
Perhaps I didn’t paint a clear picture of the sad scene in this shop, OK try the Marx Brothers trying desperately to find a problem, but couldn’t. Groucho chasing a couple of women, Harpo playing his harp (very well I might add), and Zeppo looking for trouble. That pretty much says it all.
If you can locate a schematic, I would be most grateful. Thank you!
Looks like this?
Jacques
Thank You
Jacques!
Guys, I gotta tell you, if I hadn’t watched this scenario unfold myself, I honestly wouldn’t have believed it.
I can tell you that McIntosh is over-built! OMG, if 8 screws would hold a panel they put in 20. I was also surprised that they make their own speakers, at least the woofers and mid-ranges. And this company believes in HEAVY, the 8” mid-range weighs something close to what the woofer does in the ML 120.2’s and I ain’t kidding. Now the woofers, good grief you need a bodybuilder to lift those puppies.
43 years old this coming June, 100% original except for the one changed capacitor, which I am seriously considering putting back the original as it didn’t really need changing….. I like my stuff ORIGINAL.
So what was wrong after checking the pre-amp, wires, etc? There was a light white oxidation on many of the contacts, nothing I would have given a second thought to, but I used rubbing alcohol and then I scrapped each one, several times.
It appears the contacts were plated so my rubbing produced shinny and dull areas. I don’t know if I damaged anything, but the end result was FULL POWER restored!
Thank you Jeff and Jacques for all your help.
Really glad to hear they're back up and running. Not surprising that the contacts would need refreshing after 43 years, those push on terminals can indeed oxidize.
Check it out Jeff...
http://www.echohifi.com/details/7091/McIntosh_MI-3
Price is reasonable...
Piaf:Thank you Jeff and Jacques for all your help.
As it is out of my playground, I couldnt help, but I did cross my fingers and light 2 candles for Buddha, one for each channel.
Collecting Vintage B&O is not a hobby, its a lifestyle.
Interesting indeed and thank you!
The price is most fair and the condition vastly superior to mine.
The McIntosh dealer dropped mine in the shop and shattered the fascia glass, which was replaced by an inferior one…. but what can ya do?
They also replaced a circuit board now housed in a 1” blue tube which under no circumstances could hold the original.
That said it WAS struck by lightning and I have the melted 110V plug-in to prove it. At least they got it to work. This was the same lightning strike that took out my Beogram 4002.
I replaced all the tubes, which is EASY, but feared opening the blue tube “Pandora’s box.” Something in that blue tube is not happy and affects the performance.
Plus the dealer misadjusted it so the multipath and test positions are incorrect. There are adjustment dials on the rear, but I don’t know how to do the adjustment, so it is what it is.
In a perfect world I’d send the MI-3 off for a proper repair, but I already have my Beomaster 4500 at Benny’s with the Beomaster 2400 in the wait.
However thanks to you, I now have the technical manual so at some future point, I might tackle the mysterious blue tube.
Again many, many thanks for the link and all your help!
Søren Mexico: Piaf:Thank you Jeff and Jacques for all your help. As it is out of my playground, I couldnt help, but I did cross my fingers and light 2 candles for Buddha, one for each channel.
Hi Søren, I have NO doubt you would have helped if you could as you are more than generous with your help for everyone here at BeoWorld. However the crossed fingers and the two candles lit to Buddha are much appreciated! Due to the dated style of these McIntosh ML-2M speakers I nearly parted with them several times which would have been a TERRIBLE mistake as they are amazing. The upper end is frankly not their strength, but with TWO 12” woofers containing monster magnets in each, nothing but the McIntosh ML-3 comes close to their overall performance. Suffice to say all the attention I have been paying to them of late has added greatly to my appreciation of these speakers. You might find my latest request of McIntosh amusing. My father, who was a very smart man, was fond of saying, “Not to ask is not to get.” So true, so I asked if by any remote chance they might have a set of replacement grills under a mountain of dust somewhere. A well run business like McIntosh Laboratories is beyond unlikely to have replacement parts for a 42 year old pair of speakers, but what if they did and I was too timid to ask a “stupid” question? So I asked. I am sure they laughed for an hour or so, but hey, laughter is good. Thanks again for the kind wishes! Not to mention your interest therein! P.S. If you are interested how the grills got broken I can send you a PM….. I am not sure I want to post something that ridiculous on an open forum. Jeff
Hi Søren,
I have NO doubt you would have helped if you could as you are more than generous with your help for everyone here at BeoWorld. However the crossed fingers and the two candles lit to Buddha are much appreciated!
Due to the dated style of these McIntosh ML-2M speakers I nearly parted with them several times which would have been a TERRIBLE mistake as they are amazing. The upper end is frankly not their strength, but with TWO 12” woofers containing monster magnets in each, nothing but the McIntosh ML-3 comes close to their overall performance.
Suffice to say all the attention I have been paying to them of late has added greatly to my appreciation of these speakers.
You might find my latest request of McIntosh amusing. My father, who was a very smart man, was fond of saying, “Not to ask is not to get.” So true, so I asked if by any remote chance they might have a set of replacement grills under a mountain of dust somewhere.
A well run business like McIntosh Laboratories is beyond unlikely to have replacement parts for a 42 year old pair of speakers, but what if they did and I was too timid to ask a “stupid” question? So I asked.
I am sure they laughed for an hour or so, but hey, laughter is good.
Thanks again for the kind wishes! Not to mention your interest therein!
P.S. If you are interested how the grills got broken I can send you a PM….. I am not sure I want to post something that ridiculous on an open forum.
Piaf:I am not sure I want to post something that ridiculous on an open forum.
//Bo.A long list...
BO: Piaf:I am not sure I want to post something that ridiculous on an open forum.Please do!
Laughter is what gets me through the day, even one where nothing goes right all day.
In a very different place and time my house resembled a “dream home” more than a residence to be lived in.
As such my dated 1971 McIntosh equipment cabinet and matching ML-2 speakers did not fit in to the elegant setting I was creating and all were banished to the garage, although it was a very nice garage.
Plus although exiled to the back of said garage the ML-2’s were wired up to the McIntosh in the family room and were used regularly. Worked great when entertaining.
So how did the grilles get broken? Stupidity. Well let’s just say that my depth perception is appalling in the best of circumstances, but after a nice dinner out with friends/family and a small vat of wine….. in a contact sport against a 2 ½ ton car the speakers didn’t have a chance.
Didn’t bother the car any, but the speakers suffered, repeatedly. No, it was NOT always alcohol related, on the occasion when I was in a big hurry….. another “love tap.”
It was a lot like the gag in “Home Alone” where people kept knocking down this iron statue in the driveway…. and so it was with these speakers. “Oh good grief, I did it again,” and always with a neighbor as a witness. Do something smart and no one sees it, but do something dumb…
Thank God for epoxy!
I hope this embarrassing confession provided a few laughs, or at least a smirk. Like British humor which is based on repetition….. the speaker crunching eventually became funny. Better to laugh than cry.
I have rule with my technicians, they make a failure one time, I explain to them how to do it right, if they make the same failure a second time, they get a very loud spoken lashing, the third time I fire them.
As for people remembering the bad things you do, and forgetting the smart, good things you: With the extensive traveling I have done all over the world, I see my self as a bridge builder, building bridges between people, cultures and countries, nobody ever call me a bridge builder. If you fu## your mother one time, they call you a mother fu#### for the rest of your life, (joke, sorry for the language)
Søren Mexico: I have rule with my technicians, they make a failure one time, I explain to them how to do it right, if they make the same failure a second time, they get a very loud spoken lashing, the third time I fire them. As for people remembering the bad things you do, and forgetting the smart, good things you: With the extensive traveling I have done all over the world, I see my self as a bridge builder, building bridges between people, cultures and countries, nobody ever call me a bridge builder. If you fu## your mother one time, they call you a mother fu#### for the rest of your life, (joke, sorry for the language)
I hesitated sharing that story as it makes me appear a bit more inept than I am, but I thought what the heck, maybe someone will find it amusing.
Thirty years ago people drank at dinner parties and then drove home. I certainly wouldn’t do that today under any circumstances, but we did then.
That said, the most “colourful” encounter with the ML-2 speaker was undoubtedly “influenced” by several glasses of Sangria. However a really bad day at work or just being in too much of a hurry had a similar affect.
In any case there is no getting around my terrible depth perception which is now a partially corrected optical problem made less of one with multiple prisms. However even with the prisms and using the greatest of care I occasionally tap my double tool box with the front bumper of my car. I don’t like it, but it is just part of life. It doesn’t hurt the toolbox OR the car’s bumper, but is none the less embarrassing.
You can imagine how popular I was in school sports with this then un-diagnosed problem. Catching a ball, any ball was virtually out of the question. In fact this inability to catch a ball was so well known that in an end of season game when I DID catch the ball, the other team forfeited on the spot.
I guess if I had been on your team I would have been fired. Ouch. Fortunately for me my best friend was the school all-star pitcher who overlooked my shortcoming because friendship mattered more to him than winning. And the good news is we still won the final game of the term. I even got a “that-a-boy” from the coach.
Piaf: I hope this embarrassing confession provided a few laughs,
BO: Piaf: I hope this embarrassing confession provided a few laughs, It surely did. :-)
Excellent! Than it was well worth sharing, however embarrassing.
I was a clumsy and uncoordinated kid, so I learned very early to laugh at myself. There is another sterling benefit to this laughter, if one does something klutzy and laughs at themselves, if/when others laugh too, they are laughing WITH you not at you. Priceless.
A good solution to the car parking problem is to hang a tennis ball on a string from the garage ceiling so that it is just touching your windscreen when the car is in the optimal parking position.
Graham
Piaf:There is another sterling benefit to this laughter, if one does something klutzy and laughs at themselves, if/when others laugh too, they are laughing WITH you not at you
Very true!
vikinger: A good solution to the car parking problem is to hang a tennis ball on a string from the garage ceiling so that it is just touching your windscreen when the car is in the optimal parking position. Graham
Hi Graham,
You are right about the tennis ball and string as my father-in-law uses that technique.
Perhaps now is the time to bring the Mac speakers into the modern design age with some custom built, simpler frets?
Jeff: Perhaps now is the time to bring the Mac speakers into the modern design age with some custom built, simpler frets?
Right you are, except that I am WAY ahead of you.
These Mediterranean speakers came with the avocado frets so popular in the seventies. Thank God it wasn’t Harvest Gold! I like keeping things original, but that avocado was a bit too period for me.
My mother is big on style and detested them, so she chose a very open weave cloth which is a collection of beige, cream, and taupe raw silk. Rather stylish even today. See what you think.