Building a pair of Polk Monitor 10's

K_M

willwilly wrote: »

Now I know what Imagine means. Thanks.

Imagine or Imaging?

Toolfan66

Plywood is a horrible choice...

heiney9

Monitor 10's are at the bottom of the original Monitor line. Side by side woofs cause smearing of the soundstage and just plain don't image as well as the other monitors.

Monitor 7's are the "sweet spot" of the line with the Monitor 5's not being far behind. Monitors 10's were the better speaker to "rock out" with since they had more thump and played louder than the 5's or 7's, but as far as presenting an encompassing, coherent presentation, the 5's and 7's beat the 10's pretty handily.

What you are building is NOT a Polk speaker at all. You are making a hodge podge DIY speaker. Also as has been mentioned, the x-over you bought, are for the M10's with the peerless tweeter, you can tell because it has (2) resistors in the tweeter circuit. That won't work with the sl2000 or the RD0 replacements.

Dump the sl2000 for something different. It's a wretched tweeter and even worse now that it's 20+ years old.

H9

heiney9

rmpolk wrote: »

So with that said the mont.10's series shouldn't be considered as recommended purchase?

There are better choices, but the 10's overall are very nice. I guess it depends on what you're looking for. We note the differences because we've all owned/compared them, but the differences are subtle. So they aren't poor speakers, just don't have all the same "magic" the other Monitors seem to possess.

H9

willwilly

heiney9 wrote: »

What you are building is NOT a Polk speaker at all. You are making a hodge podge DIY speaker. Also as has been mentioned, the x-over you bought, are for the M10's with the peerless tweeter, you can tell because it has (2) resistors in the tweeter circuit. That won't work with the sl2000 or the RD0 replacements.

Dump the sl2000 for something different. It's a wretched tweeter and even worse now that it's 20+ years old.

H9

Hodge Podge? I'm not sure if that is a fair assessment.

The crossover schematic I posted is what I will be following with the aforementioned Sonicap capacitors and Mills resistors, keeping the existing inductors. All I will be using from the original is the inductors and the circuit board.

Tweeters are RD0-194's (New) As I understand it, these will work with the posted schematic. If not, please let me know what I will need to change on the crossover.

Polk 10" PR's

Drivers are MW6503's (vintage)

The cabinet will be identical dimensions but will be made of solid wood rather than particle board.

heiney9

Ok, I guess I was more or less commenting on your earlier posts about using Dayton drivers, using the older M10 x-overs and statements about Parts Express "designing" a new (better in your words) cross-over.

I apologize if I missed where you were going to build an exact replica.

If you get the baffle dimensions correct and use mdf and all original drivers and cross-over's you should get it real close.

Just curious what your total cost is so far?

H9

willwilly

DSkip wrote: »

Will, I apologize if I ruffled your feathers. I've been trying to voice my concerns as well as make suggestions when I voiced them. Wood is often a poor choice for speaker design because of its resonance. This is why most use a veneer on top. It gives the appearance of wood while also allowing use of better material for the performance of the speaker.

No feathers ruffled, we're just not speaking the same language metaphorically. But I'm starting to see the light. I can accept that the resonance of the material is important. What I'm trying to discern is how important. Also trying to quantify the effects of different materials.

All the comments I'm hearing are subjective, "bad" , "smearing of sound stage" and "poor imaging". I have a feel of what those terms mean now thanks to the links, but few talk in quantitative terms. How bad? How much smearing, how poor?

There is certainly a lot of passion here but little flexibility in the potential for different tastes. Of course I'm way out of my league because I can't speak intelligently of what I like!


So:

Subjectively MDF certainly does have a softer density than real wood, as well as the low density particle board from the originals.

I'm not a fan of MDF from a wood working point of view but obviously I need to correct that when talking about speaker cabinet construction.

Veneered MDF is an option that would satisfy my need for a furniture quality look but keep the performance of the speaker somewhat predictable.

heiney9

willwilly wrote: »

All the comments I'm hearing are subjective, "bad" , "smearing of sound stage" and "poor imaging". I have a feel of what those terms mean now thanks to the links, but few talk in quantitative terms. How bad? How much smearing, how poor?

There is certainly a lot of passion here but little flexibility in the potential for different tastes. Of course I'm way out of my league because I can't speak intelligently of what I like!

It's compared to the other Monitor speakers. If you think about what other speakers (good speakers) so you see any with side by side woofers other than SDA's, which are a completely different animal? Not many if any. Lobing is the issue, point source issues, tweeter continuity, etc.

The 5's and 7's in the same line perform better as far as image placement, instrument timbre, vocals, etc. because they don't suffer the same effects side by side woofers can cause.

In the grand scheme, it's subtle and may not even be noticeable until you listen to a similar speaker that doesn't exhibit these characteristics. Are your speakers going to be unlistenable? Certainly not, they just won't exhibit the same amount of openness and timbre and vocal quality and imaging as the 7's or the 5's. or other non side by side woofer type of speaker.

H9

dromunds

Misspoke earlier, Nightfall has RTA-12B's for sale. Brain faart.

willwilly

It's compared to the other Monitor speakers. If you think about what other speakers (good speakers) so you see any with side by side woofers other than SDA's, which are a completely different animal? Not many if any. Lobing is the issue, point source issues, tweeter continuity, etc.

The 5's and 7's in the same line perform better as far as image placement, instrument timbre, vocals, etc. because they don't suffer the same effects side by side woofers can cause.

In the grand scheme, it's subtle and may not even be noticeable until you listen to a similar speaker that doesn't exhibit these characteristics. Are your speakers going to be unlistenable? Certainly not, they just won't exhibit the same amount of openness and timbre and vocal quality and imaging as the 7's or the 5's. or other non side by side woofer type of speaker.

H9

[/quote]

Now that helps. Thank you for taking the time to put it so eloquently and easy to understand. I do love my 5's and 4 rears and... Guess I'll get to make a good comparison of single mids to doubles.

Cost so far:

Drivers: Polk MW6503's $100 used
PR: Polk 10" $35 used
Tweeters: RD0-194's new $100
Crossovers used: $35

Crossover components: $235 Ouch!

Cabinets: Nothing, I might buy a sheet of MDF if I go that way but all the cabinet material is material from other non-speaker related.

So that puts me at $560. I did say money wasn't the motivating factor here. I could just as easily bought a pair and been done but what is the fun of that.

My return is in the journey and the knowledge gained...

willwilly

rmpolk,

I am diving head first into the ways of loud speakers. Extremely good point!

At this point, being cost effective has been thrown out the window. I am comfortable that my 10's will cost far more than others but that's not the goal.

I'm paying not only for the materials, I'm building the cabinets, doing the electrical update of the crossover and most importantly, getting a crash course in the polk way of making speakers. People should consider themselves lucky to have access to such an informative forum and a manufacturer that promotes the love of their blast's from the past by taking advantage of the audio grease monkey market.

So in just a few days I understand imaging, the term soundstage and now I'm trying to get my head around lobing. Quite the interesting phenomenon. I can now see why everyone piled on when I said I wanted to make a pair of 10's rather than 7's or even fives. I haven't given up on the 10's yet and now I'm investigating what can be done to reduce the effect of lobing but still keep the component layout the same.

I'm not anywhere near completely understanding lobing and I don't think most do from what I read but I have followed the links some have suggested.

It was mentioned M12's handle this in the electronics. Once I understand the issue a bit more I think I will investigate how 12's work and see if it will apply to 10's. Still staying in the Polk genre.

willwilly

So lobing, this is what I found that helped me the most. A lot of information on what it is, not much dedicated to the solution. Though setting your 10's on their sides apparently reduces the effect, at least horizontally.

http://www.kvart-bolge.com/#!Acoustic-Lobing-Explained/c1rr6/55a407120cf25466c29f49b3

heiney9

RTA 12 handle it in the x-over as they are a true "time aligned" speaker.

I am not aware that Monitor 12's (completely different speaker than the RTA 12), which are fairly rare, took care of the issues in the crossover. In fact the Monitor 12's don't get much favor around here for the same reasons and I would guess (as it's been a long time since I've listened to a pair) they have the same issues, perhaps even more exaggerated, IIRC.

The Monitor 12 was short lived.

H9

willwilly

So what about playing with the component configuration. Here are some options I came up with. I could be creating a whole list of other issues that would result in some undesirable effects but lobing is a tricky problem.

I didn't consider this but it is obvious now, the center channel for most theater systems is a side by side configuration. they try to minimize by slightly curving the front face, i.e. pointing the center drivers slightly out.

willwilly

Or better yet how about Polk 7-10's or Super 7's! Now this is interesting. What are your thoughts. Go ahead, let'r rip...

heiney9

No to all of it. There is solid science involved in speaker design. I suggest you study it, if you really want to be a diy speaker maker. Or copy someone else's design.

H9

heiney9

HT center channels play a limited output and limited frequencies. Don't confuse HT with 2 channel. Two different ideas and implementation.

H9

notified

I seem to recall reading somewhere that although its much cheaper in material cost to make a speaker with a passive radiator it is however much more difficult in design to properly tune the box for its best performance

willwilly

heiney9 wrote: »

HT center channels play a limited output and limited frequencies. Don't confuse HT with 2 channel. Two different ideas and implementation.

H9

Wasn't making a comparison, just discussing the mechanism of lobing and how it effects all
Systems...

willwilly

Solid science.eh? So something more than, No, that won't work, copy somebody else. I ll lok into it...

willwilly

notified wrote: »

I seem to recall reading somewhere that although its much cheaper in material cost to make a speaker with a passive radiator it is however much more difficult in design to properly tune the box for its best performance

I can imagine the difficulty in coming up with a unique design, the R&D, the real world application... I'll have to see if there is some virtual simulation software to get close because from an aesthetic point of view, but I'm learning aesthetics are way down the list of considerations when making a good speaker.
I also think I'm getting further and further away from the "find it on the internet" realm.

willwilly

Wow, Quite the selection speaker box design software available. I think I should stay with what Polk designed and lobing be damn ed unless someone wants to run my super 7 design through their software.

willwilly

So why speaker Rings?

Nightfall

Larry's rings? They allow a tighter seal between the driver and the baffle than the wood screws do plus the wood screws can strip easy.

Toolfan66

I find it funny how it can be posted about Polk speakers that Matt sold to many people, and according to some here are not up to par with other speakers that he designed and sold as well..

Sometimes I think just having fun with a project gets lost in the "it needs to be this or it's going to s.u.c.k and not be this" "you would be better off just buying this"

It's sad really..

Obviously everything Matt, and Polk in general didn't, and don't put out speakers that are up to some of your standards, are you posting or emailing them on how they should build a speaker? I didn't think so.. The funnier thing is there are many people out there enjoying those speakers that don't fit "your standards"..

Let the guy have fun, give him some pointers, and help him along, you never know they might just sound fantastic, and better yet, makes him happy with what he created...

Toolfan66

With that said, please don't use plywood!!

willwilly

Toolfan66 wrote: »

With that said, please don't use plywood!!

MDF it is! How can I argue with that! When I get to that point, I'm sure I'll have more questions!

Thanks such for your sensibly words! I was getting close to chucking it all and buying some earphones...

But I'm not so easily swayed...

willwilly

Wow, no pressure here.

I'm sticking to my guns and building a clone set of 10's with real wood veneer, maybe Cherry, maybe Walnut.

If I duplicate internal dimensions, Polk components and correct baffling, one should expect very simular results. I'll know when I place them next to my fives.

Thanks again everyone! Now for a little less talk and more work, with pictures.

willwilly

DSkip wrote: »

With the time investment and expectations he had, I think this has been a very informative and productive.

It has! Look at it this way, I have a whole set of cheap drivers and tweeters for the next project!

Toolfan66

Skip, I agree, but you know as well as I do when someone starts a project like this, they usually get torn down before they get started..

I mean really, we are talking about Monitor 10's here, not someone that wants to clone some Ushers, or Sonus Faber's..

We're talking about a set of 30 year old speakers, that apparently Matt designed and are not as good as some of his other designs but sold to the general public anyways...

I would bet a million dollars that if someone built a set of monitor 10's or even set of 7's cabinets, built them to exact specs, used the same wood, and put the same drivers, x overs, and tweeters, there would be a few here saying they can here a difference, and the originals are better, yet Matt/Polk was known for using up older stock parts as they moved to the new line of speakers they were pushing..

Again, we are talking about a guy that wants to build a set of his own monitor 10's, it's not like he wants to reinvent the SDA technology...