Monitor 7 Details, Details...

Klop

Hello all,
I'm not exactly sure what the custom is on introductions, so I'll try to be brief. Feel free to skip past it if you like.

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After an introduction to Polks via the local thrift store, I've now found myself quite enamored by them. The model was a set of very nice Monitor5's I picked up for $35. Though that was probably high by thrift store standards, they seemed like well-made speakers and I was looking to fill out my mini-theater. Indeed they were good to me... until I found some Monitor7's the following year. These are my current fronts & I figure they'll probably stay that way for quite some time.
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Now, as for the questions I'm thinking there's bound to be someone out there who has some insight. From what I could tell, this hasn't been directly addressed elsewhere, so here goes. Thanks in advance for any light you can shed.

(to help organize it a bit, my actual questions are printed in bold)

1. In wanting to freshen up the crossovers (as well as stay cheap), I located some 10uF epoxy-dipped polypropylene caps which I used for the high-pass section.

This has "brightened" them up considerably, but I'm wondering if the cap value is too far off spec. I think this shifted the crossover point up by about 330 Hz (1660 - 1990Hz).

In substituting 10uF for 12uF, have I moved away from the "Monitor 7 sound" to something uncharacteristically bright, or were my old caps really that bad?

2. Likewise, I've replaced the 34uF low-pass cap with a 33uF NP electrolytic without any noticeable difference. My impression is that the mid-range area is rather thin on these.

So would springing for some poly caps in the low-pass section yield a considerable improvement in mid-range presence?

3. I noticed my 5's had the stuffing descending halfway down into the mid-range cavity, so I replicated that in the 7's.

But, is there a specific "factory arrangement" for the polyfil in these models?

Alternatively I could unfold it to cover the entire back of both speakers, push it up behind the tweeter only, or spread it over the whole back of the cabinet. Or maybe it doesn't matter a bit...

4. And finally, I've seen some posts showing the 7's once had their own stands.

I'm curious, what am I missing out on without the special tilted factory stands?

Imaging seems pretty focused to me, though I'll admit I didn't even know what imaging was that long ago.

Again, my thanks & I look forward to learning more!

McLoki

Welcome to Club Polk. Great deal on the monitor 7's - they are awesome speakers.

I would upgrade the crossovers with exact replacement values. (you can find the schematic in this thread....) for inexpensive, good sounding caps I recommend the dayton brand from parts express and Mills resistors.

Not sure on the polyfill, but it is mainly used for the bass drivers, so I would drop it down there rather than put it up behind the tweeter.

The original stands were tilted at about a 5degree angle to allow for a poor mans time alignment. I used non-factory wood stand and just cut the uprights at a 5degree angle for my Monitor 10's. (another goodwill purchase )

Welcome to club polk - any other questions, just ask.

Michael

Klop

McLoki wrote: »

Welcome to Club Polk. Great deal on the monitor 7's - they are awesome speakers.

Thanks for the welcome. I'm thinking My 7's need further tweaking to be truly awesome, though they are some of the nicest I've owned so far. The hitch was that both MW 6502's were seized when I got 'em (though for $8 it was still a deal). My M5's supplied the drivers and are now laying dormant themselves.

I would upgrade the crossovers with exact replacement values. (you can find the schematic in this thread....) for inexpensive, good sounding caps I recommend the dayton brand from parts express and Mills resistors.

Yeah that's probably the route I should have taken to begin with. I guess being cheap ultimately ends up costing more.

I'm also curious if anyone has compared just the resistors in these and been able to tell a difference (sand cast vs. mills). Or is it more of a "they spec better and they're cheap, might as well" type thing?

Not sure on the polyfill, but it is mainly used for the bass drivers, so I would drop it down there rather than put it up behind the tweeter.

That sorta bolsters my original assumption, so I'll fix 'em. Thanks.

The original stands were tilted at about a 5degree angle to allow for a poor mans time alignment. I used non-factory wood stand and just cut the uprights at a 5degree angle for my Monitor 10's. (another goodwill purchase )

Welcome to club polk - any other questions, just ask.

Michael

By chance were your stands the 4-something inch height of the originals, or is it equally effective to put the tilt on a taller (say 23") stand?

Much thanks for your help, suggestions & warm welcome.

comfortablycurt

Welcome to Club Polk.:)

The Monitor 7's are some awesome speakers! I've got a pair of Monitor 7A's, with Peerless tweeters. For the price they can be had at, I don't think you can beat them with anything new.

What kind of Monitor 7's do you have? What kind of tweeter do they have? Any pics?

One common upgrade to the non-Peerless Monitor 7's is the replacement of the tweeter, with a newer RD0-194 direct from Polk. It's a much smoother sounding tweeter, and eliminates the frequency spikes that the SL2000's had.

Generally when people upgrade the crossovers they stick with the same original values. However, the original Polk cap's were 10% tolerance, which allowed for a lot of play in either direction. Sometimes, when replacing them with caps with tighter tolerances, it can kind of shift the crossover points and make them sound slightly different.

Search the forum, there are a bunch of threads here regarding crossover upgrades. Here's a good one by heiney9....

http://www.polkaudio.com/forums/showthread.php?t=51420


Regarding the polyfill, it should come down to the bottom of the mid-woofer, but not so far as to cover the passive radiator.


The stands that came with the Monitor's served two main purposes. One was to achieve a cheap form of time alignment. Notice that on a lot of higher end speakers, the tweeters are mounted farther back in, or on top of, the cabinets. This is because high frequency and low frequency waves have different wavelengths, and arrive at your ears at slightly different times. Pulling the tweeter back slightly helps to compensate for that.

The stands also served the purpose of angling the tweeters up, and pointing them more directly towards your ears. This helps to compensate for the shortness of the speakers when sitting on the floor.

I don't think I'd mount them on a stand as tall as 23"...especially not with the angle. You'd be surprised how much of a difference even the shorter 5" high stands can make. It makes the speakers feel a lot larger...taller. It also helps to tighten up the mid-range and upper bass noticeably.

Klop

comfortablycurt wrote: »

Welcome to Club Polk.:)

Thank you.

What kind of Monitor 7's do you have? What kind of tweeter do they have? Any pics?

I think they're 7C's, but could be B's as I'm not entirely clear what differentiates those two. They're non-peerless tweeters, for certain (SL 2000) and dated July 22, 1987. No pictures yet, though they're pretty unremarkable examples of the model. I cleaned them up considerably, but they still won't win any beauty contest.

One common upgrade to the non-Peerless Monitor 7's is the replacement of the tweeter, with a newer RD0-194 direct from Polk. It's a much smoother sounding tweeter, and eliminates the frequency spikes that the SL2000's had.

I've heard this upgrade mentioned in the forums, but wondered how "bad" the SL2K really was. One M7 owner (not sure if he's on the forum) told me that the spike was around 13kHz which only affects the upper harmonics making it "not that big of a deal" for most music. I'll admit to having not noticed it, but my ears may be of a less precious metal than some...

Generally when people upgrade the crossovers they stick with the same original values. However, the original Polk cap's were 10% tolerance, which allowed for a lot of play in either direction. Sometimes, when replacing them with caps with tighter tolerances, it can kind of shift the crossover points and make them sound slightly different.

I actually had that thread by heiney9 already bookmarked.
It was a great preview for what I was about to get into, before I experimented with the cheapy caps.

Regarding the polyfill, it should come down to the bottom of the mid-woofer, but not so far as to cover the passive radiator.

That sounds like the perfect reference point & that's how I re-situated it.

I don't think I'd mount them on a stand as tall as 23"...especially not with the angle. You'd be surprised how much of a difference even the shorter 5" high stands can make. It makes the speakers feel a lot larger...taller. It also helps to tighten up the mid-range and upper bass noticeably.

Just when I was about to write off the necessity of such stands for time alignment (based on this info), you've got me interested again with that last part.

Thank you for your insight!

hearingimpared

Welcome to Club Polk Klop!

Klop

hearingimpared wrote: »

Welcome to Club Polk Klop!

Thank you.