Monitor 7A and 10C

jimbo1421

Hello everyone.

Yesterday I picked up a pair of Monitor 7As off CL for $75. They had been in a bookstore since new in 1979 which I guess is like the proverbial used car that was only driven by a little old lady on Sundays. They are in good shape cosmetically, except that the back on one of them is warped away from the top as if it had never been fully pulled home when clamped together during assembly. Has anyone ever seen this? I will be pulling the drivers to reseal them with Moretite so I can inspect the interior of the joint at that time. Maybe I can draw it into place with some clamps.

But the sound I get from the 7As is so much better than my Monitor 10s that I wonder what the heck is wrong with the 10s. I had been thinking that my worn records, mp3s, or computer CD player were to blame for distortion in the high frequencies. But the 7A gets rid of many of those problems. It is very clean sounding with nicely defined instruments.

On the Monitor 10s I repaired some open joints in the cabinets and resealed the drivers with a Moretite equivalent product. I also got the RDO-194 replacement tweeters and replaced one for comparison to the old SL-2000. Playing monaural records and switching the balance from left to right, I can't say I heard much difference. I have heard the term "smeared" used to describe the sound; maybe that is right word for what I am hearing.

What could be wrong? Do the crossovers need to be rebuilt? They are 21 years old, after all. Or could it be a room effect? My living room is 13' x 19' x 8'-3"; the speakers are 6' apart on the 13' wall and about 18" away from the wall. The right speakers is about 18" from a big record cabinet, the left is about 30" away from the front door, which is a possible reflection spot. The room is pretty cluttered with furniture, but no sound absorbing wall treatments like curtains, and only one 6' x 9' area rug on a hardwood floor. With dual mid woofers am I getting multiple reflections that muddy up the sound? Maybe the 7As, with a single inline MW, are just right for the space. Do the 10s just not have enough room around them to work effectively?

Anyone have any thoughts about this?

Jim

comfortablycurt

It's very possible that you just prefer the sound of the 7's. The Peerless tweeters are excellent, and many people prefer them to the RD0's. A lot of people complain about the 10's having a smeared sounding mid-range due to the side by side MW's. The 7's, with only one MW, obviously wouldn't have that problem. Just because the 10's have a higher model number, doesn't necessarily mean that they're a better sounding speaker for your tastes. Just like some people prefer smaller bookshelves to larger floorstanders.

I certainly love my 7A's. For the price they can be had for, they sound way too good. Some excellent speakers.

bluecomet

The monitor 7a's are great speakers. I also have the monitor 10A's. The peerless tweeters help the 10's greatly. You have the SL2000's in the monitor 10c's. I believe controlling the muddled sound you are hearing is going to be tougher. The greatest help to my monitor 10A's is a 3 band parametric equalizer. I would change the tweeters to RDO's and find a Parametric equalizer. You will be surprised by what you hear.

jimbo1421

bluecomet wrote: »

The monitor 7a's are great speakers. I also have the monitor 10A's. The peerless tweeters help the 10's greatly. You have the SL2000's in the monitor 10c's. I believe controlling the muddled sound you are hearing is going to be tougher. The greatest help to my monitor 10A's is a 3 band parametric equalizer. I would change the tweeters to RDO's and find a Parametric equalizer. You will be surprised by what you hear.

Thanks for your comments bluecomet. What size room do you have your M10s in? Like I said, I have mine 6' apart on the short wall of a 13' x 19' room with the sweet spot about 9' away. Are the M10s better suited to larger rooms?

Jim

jimbo1421

comfortablycurt wrote: »

It's very possible that you just prefer the sound of the 7's. The Peerless tweeters are excellent, and many people prefer them to the RD0's. A lot of people complain about the 10's having a smeared sounding mid-range due to the side by side MW's. The 7's, with only one MW, obviously wouldn't have that problem. Just because the 10's have a higher model number, doesn't necessarily mean that they're a better sounding speaker for your tastes. Just like some people prefer smaller bookshelves to larger floorstanders.

I certainly love my 7A's. For the price they can be had for, they sound way too good. Some excellent speakers.

Thanks CC. They do sound good. The M10s have a more spacious sound to them and are quite good at lower frequencies. But the 7As are definitely keepers.

Do you or anyone know the nominal impedance of the 7A or 10B? Polk's Vintage page says 8 ohms for both. Two different manuals from polksda.com rate the M10B at 6 ohms; the 7C is rated 4 ohms in one manual and 6 ohms in the other.

Jim

comfortablycurt

jimbo1421 wrote: »

Thanks CC. They do sound good. The M10s have a more spacious sound to them and are quite good at lower frequencies. But the 7As are definitely keepers.

Do you or anyone know the nominal impedance of the 7A or 10B? Polk's Vintage page says 8 ohms for both. Two different manuals from polksda.com rate the M10B at 6 ohms; the 7C is rated 4 ohms in one manual and 6 ohms in the other.

Jim

Yes, the 10's definitely have the edge in the low end. For my tastes though, the 7A's provide plenty of clean, tight, punchy bass though. Eventually I'd like to get a pair of Peerless M10A's, so I can make my own comparison.

I can't speak for the rest of the speakers you mentioned, but the 7A's are 8ohms nominal. The way I've always understood it, all of the Vintage Monitors were 8 ohms nominal, regardless of what the manuals/product pages might say. Don't take that as fact though, I could be wrong.

bluecomet

The M10's you have are fine for the size room you have. I have a large room 26x 30 that I have my speakers in and they easily fill the room with sound. The gear you use with these speakers are very important to get the most out of these speakers. The M7's are better balanced and more forgiving of the gear you use. The M10's have more bass but using a sub with M7's are an excellent combination. I doubt if vintage Monitors are 8 ohms. I am sure someone knows but I would have to think that 6 ohms would be more accurate. I use amps that go down to 4 ohms so I really don't think about it when I use them.

BigMac

Hi. I have a pair of M-10b and love the sound. I have tried many times to 'hear' the smeared midrange everyone talks about to no avail. My 10b are very clear and detailed and have great low end. They are 6-7' apart, about 10" away from the back wall and my right speaker is 12" from a side wall. I have tried quite a few different amps, cd players, receivers, etc.. with the 10b and have come to the conclusion that once you start feeding these more than 100wpc, that is when they start to shine. I had these hooked up to a 100 wpc receiver (2 different ones-Onkyo and a higher end Pioneer and a 50 wpc H/k which was the worse of the bunch) and they sounded 'ok' but nothing special. I also had them hooked up to an Adcom 535 and that did improve the sound to being enjoyable for long listening sessions. Now I have them hooked up to a 200wpc Luxman amp and they sound fantastic. I remember reading somewhere that the average impedence for the M10 is 6 ohm with dips a little lower sometimes depending on the material being played. Needless to say I am very pleased with the sound I am hearing. Having the right combo of equipment,wpc,cables,room size,power conditioner,furniture,curtains,etc. all play a part in the overall sound and I suppose I was blessed by the Pope when he came to D.C. not to long ago.

I have not heard the 7s but I have heard the RT55i and M5 in my home and I disliked both (I did side by side comparison with the M10b). The M5 was very blah and thin sounding. I could not stand to listen to them for more than a few minutes. The RT55i sounded like there were a few horse blankets on top, very compressed sounding and was missing detail in the higher frequencies. Neither the M5 nor the RT55i would I own for listening. The one thing that did surprise me was the amount of bass the RT55i had but it was very Cerwin Vega like (boomy vs punchy). Even my wife who is not a big audio fan anyway disliked how both of these speakers sounded as well. I would really like to hear the M7s to listen to what all the fuss is about. Everyone swears by the 7s but so far the 10b are tops in my book. Maybe my speakers were soaked with wine or something because they just keep getting better with age.:D

StantonZ

I have "all original equipment" 10b's and you may have a point: I have driven mine (for years) with a Yamaha DSP-A1 which has plenty of power to burn. In fact, I can't even get to half volume without blowing everything away. These (old) Yamaha amps are well suited to drive < 8 Ohm loads (they even have a switch), and that probably helps the notoriously low impedance 10b's as well. I've thought about replacing the (SL-2000) tweeters on my 10b's, but I always thought the caps, etc. should go first; it's hard to mess with something that sounds good to me.

Flash21

BigMac wrote: »

Hi. I have a pair of M-10b and love the sound. I have tried many times to 'hear' the smeared midrange everyone talks about to no avail. My 10b are very clear and detailed and have great low end.

People who say that assume that the side-by-side midbass drivers will muddle imaging, forgetting that the tweeter provides the VAST majority of imaging information. I think they are short-changing the 10Bs unduly...they were my main speakers for over 20 years.

jimbo1421

Are the Monitor 10Bs that you are all talking about the ones with the brushed chrome tweeters? I have the 10Cs and have replaced the SL2000 tweeters with the RDO-194s. I still don't like them all that much, now that I have compared them with the M7As. The seller of the M7s also had a pair of 10Bs with the brushed chrome tweeters. Maybe I should grab them as well for a final comparison.

I have a Parasound HCA-1000a to power them with; 125 wpc into 8 ohms, 200 wpc into 4 ohms. Should be enough.

Jim

NJPOLKER

Jimbo
Have you given thought to re-building the x-overs? It is a simple project and cost effective too. There are plenty of posts/threads on the subject here for your use. Give it a shot you won't be disappointed.

Flash21

jimbo1421 wrote: »

Are the Monitor 10Bs that you are all talking about the ones with the brushed chrome tweeters?

Mine had the SL2000s, no chrome. I did install RDO-194s at one point, which mellowed them out a bit.

heiney9

Flash21 wrote: »

People who say that assume that the side-by-side midbass drivers will muddle imaging, forgetting that the tweeter provides the VAST majority of imaging information. I think they are short-changing the 10Bs unduly...they were my main speakers for over 20 years.

Actually that's not true. The only signals that don't have auditory cues are bass. It's somewhat directional but it has little to no "imaging" properties.

Much of the imaging comes from the midrange as well. On the 10B's there are timing issue with the drivers overlapping the dispersion, which cause a muddled somewhat garbled sound compared to other designs.

It's not obvious until you start comparing the 7's or 5's using the same source material, etc.

The 10B's do in fact suffer from muddled imaging; this is why many prefer the sound of Monitor 7's or even the 5's.

The 10 was/is a "calssic" Polk speaker and it's great for jamming out to and it certainly provides some solid bass..........but in the end if your looking for precise and natural sounding vocals, etc.........the 10 is not the best choice.

H9

Flash21

heiney9 wrote: »

Actually that's not true. The only signals that don't have auditory cues are bass.

How is that different from what I said? It is a sliding scale actually, and treble provides most of the imaging, midrange some, bass very little.

Note that Polk calls the 6" drivers "Midbass" drivers. I'm not saying they have no influence on imaging, just that they don't go as high as people think, and consequently don't affect imaging all that much.

If you are going for that nth degree of imaging quality, it might matter, but is that really what we are talking about in this thread?

heiney9

But they do affect imaging a great deal. And Polk's Midbass drivers go much higher and lower than a normal mid driver in many other popular speakers.

The tweeter has the most imaging cues, but the Polk midbass drivers aren't far behind. Again sometime compare 10's, 7's and 5's and you'll be amazed at the clarity of the 7's and 5's on vocals and upper midrange instruments compared to the 10's. This is directly the result of side by side mid drivers.

Other than the rare Monitor 12's Polk never used that configuration again and you don;t see too many other manufacturer's using it either (then or now).

This of course excludes the special properties of SDA's.

H9

bluecomet

I agree. This is why the three band parametric equalizer is a must if you want to bring out the best in the monitor 10's. With the EQ you can control the mids and it helps the imaging greatly. It is one of the few Polk speakers that an EQ can truely inhance. The crossover mods are also going to make these speakers come to life. The early monitor 10's with the peerless tweeters are the gem in the monitor 10's series I believe. The peerless tweeter makes a big difference.

BigMac

heiney9 wrote: »

It's not obvious until you start comparing the 7's or 5's using the same source material, etc.

I did compare the M5 and their detail pales in comparsion imo. Maybe my 10s are magical or something ( maybe there are those magic pebbles in there) but when I a/b the 5 vs 10 the 10 won every time....hands down imo. I have really tried to hear the muddy imaging, I mean like for hours on end with all types of music and I cannot hear it for the life of me. Good for me though as I will not need spend more right now on speakers. On a side note I like the M10b sound so much I was going to get them reveneered. A guy from a cabinet shop came over (one of the best around that does this kind of work on the side) and when I was quoted how much it would be I almost crapped myself. I am still thinking about it though............maybe in the future, maybe.

ND13

jimbo1421 wrote: »

Hello everyone.


But the sound I get from the 7As is so much better than my Monitor 10s that I wonder what the heck is wrong with the 10s


Jim

''Be cause the 7s do sound better than the 10's. The 10s are no slouch and will produce more SPLs and bass, but are not nearly as accurate due to the side by side mids which smear the soundstage.

I'd take one pair of clean 7As with Peerless tweeters over 2 pairs of 10s. YMMV and just my opinion.

jimbo1421

I just got back with the 10Bs, so now I get to settle the issue (for myself at least).

Jim

PS: They came with stands, too.

jimbo1421

I am going to have a hard time deciding whether to keep the 7As or 10Bs in my 2 channel system. I played Pictures at an Exhibition and Chopin's Ballade #1 through on both. I have to give the 7As the thumbs up for sweeter highs and the 10Bs credit for a more spacious sound. I don't hear the "smearing" that I heard on the 10Cs. I am not sure which tweeter the 7As have, the Danish or USA Peerless. They are black, no logo, with the hole in the dome. The 10Bs have the brushed chrome tweeter (SL1000?). As bluecomet said the 7As maybe more forgiving and the 10Bs more accurate, i.e., harsh with my computer's CD player. Can I put the 7A tweeter into the 10B without upsetting the crossover?

For the longest time I was eyeing the LSi9s. Now, for much less than half the price, I have 3 pairs of vintage Monitors to study and work on and fiddle with. Much more fun than just spending money.

Jim

comfortablycurt

That sounds like the American Peerless tweeter.

No, you can't put it into the 10B. The cutout for the Peerless tweeter is a bit larger that the cutouts for the other tweeters. It wouldn't seal up against the cabinet well enough to keep it airtight. The cabinet could be modified to accept it, but the crossovers for the Peerless tweets use an extra resistor in the signal path, so the XO's would have to be modified as well.

jimbo1421

comfortablycurt wrote: »

That sounds like the American Peerless tweeter.

No, you can't put it into the 10B. The cutout for the Peerless tweeter is a bit larger that the cutouts for the other tweeters. It wouldn't seal up against the cabinet well enough to keep it airtight. The cabinet could be modified to accept it, but the crossovers for the Peerless tweets use an extra resistor in the signal path, so the XO's would have to be modified as well.

Thanks CC. I thought that might be so.

Jim

geppy1

I think he said his 10Bs have the SL1000 which is the exact same size as the Peerless so it would work Later 10Bs 86-87 use the SL2000 which has a larger hole and that will not work. I have swapped all these tweeters in and out of 10s and RTA 12 so many times I have worn out the holes but I have learned a few things. I like both of the Peerless tweeters. I also should point out in my experience (and agrreed with by other who have heard them) the SL1000 does offer a more open and transparent sound and time and time again is found to be more natural on voices and cymbles HOWEVER if the program material is bright they can go over the edge a little. The SL2000 DO NOT sound like the 1000. They sound wierd and my wife said like tinfoil. I should also point out the all to well talked about supposed peak in these tweeters comes from the crossover.
As far as the 10s. I have had mine for 26 years and never had any issue with the midrange. In fact they are very open in the midrange and seem more so to me then the 7s I have heard. Can they get a little thick once and awhile yes but It is far out weighed by the better very low end and the wide open sound. I am sorry to say if this was such an issue would it have been their best selling speaker and would they have used it from 1978 to 1992 in one form or another?? My god thats 14 years they were fooling us!! I have prefeered my 10s to 2 pairs of SDAs I tried and the LSI15. I now use RTA12s. This is all about personal preference. By the way one of the main reasons you not see drivers side by side has more to do with the change in lifestyles and what people want in their livng room then anything else. They want small and narrow.
On seperate note the RTA 15TL s lost to the RTA 12s in my little shootout. Three people were involved. I will write the review later.

heiney9

Except I do believe the x-over is different for the Peerless and sl1000. That right there makes the swapping results skewed.

To the OP, enjoy them both for awhile and flip the one you like the least or keep 'em oth and enjoy them. The best way to know for sure is to do some listening to both. It's not a 100% accurate comparison since they have different tweets and x-overs.......but it will have to do.

H9

Vette C6.r

Same thing with me. my 7a's sound better than anything that I have in my inventory. The 10's don't have the Peerless tweets.

You're not the only one that thinks they sound better.

geppy1

It seems alot of these crossover are alike but have different suppliers for the caps. I have never had a set of early 10Bs (84-85) which used the SL1000 and my crossover on my 10s was redone by ken years ago. Hard to know. i know on the RTA 12Bs and early Cs used the same crossover for both American made peerless and the SL1000. The early Denmark Peerless had several more caps on the top one.

jimbo1421

bluecomet wrote: »

I agree. This is why the three band parametric equalizer is a must if you want to bring out the best in the monitor 10's. With the EQ you can control the mids and it helps the imaging greatly. It is one of the few Polk speakers that an EQ can truely inhance.

Hi bluecomet,

Would you go into more detail about how you use an equalizer? What particular problems do you solve with it? iTunes and a few other of my MacBook Pro's audio software include 10 band equalizers that I could play with before I buy one. Is your 3 band parametric equalizer the same as these, except with fewer bands controlling a broader frequency?

Jim

bluecomet

A three band equalizer is different the a normal EQ. It would take too long to tell you the difference. You should google a parametric equalizer. It will tell you how it operates. I also have a 12 band normal equalizer. It can help somewhat but the normal slider EQ's are not as good. I have a old SAE 3 band EQ. The company no longer exists but they made excellent gear back in the day. You may be able to find one for a hundred dollars or less. They are well worth the money especially if you decide to keep your Monitor 10's. It will benefit all normal speakers except the SDA's which will mess with the SDA effect.

jimbo1421

NJPOLKER wrote: »

Jimbo
Have you given thought to re-building the x-overs? It is a simple project and cost effective too. There are plenty of posts/threads on the subject here for your use. Give it a shot you won't be disappointed.

Hi NJP,

I am thinking of doing just that, but I wonder just what problems a crossover rebuild would solve. I have been breaking in the RDO-194 tweeters in the M10Cs. They are now to the point of being about equal in quality to the Peerless tweeters. I still like the spacious sound of the M10s and the better definition of the M7As. Can't decide between them.

I am getting to the point where I need to work on the input side of things: record cleaning, turntable tuneup, and a CD player or DAC better than my laptop's.

Where in NJ do you live? I grew up in Maplewood.

Jim