Building a pair of Polk Monitor 10's

willwilly

My name is William and I have decided to build a pair of DIY Polk Monitor 10's.

I have been a long time fan of Polk Monitor Series speakers ever since I heard my first pair of 10's in High School. Now later in life, I have been revisiting the old days of big audio systems and precise speakers. I have put together a couple systems using vintage components I remember always wanting but could never scrape up enough lawn mowing money to buy.

I have a pair of Polk 5's and two pairs of 4's. They sound great and now I'm ready to move up to the next step. I'm skipping the 7's and want a pair of unique 10's.

I have searched the webs for a decent pair of 10's over the years but they are pricey, risky to ship and will most likely either be ready for replacement parts or have already been fiddled with. I got burnt on one of my pairs of 4's buying them from eBay. They arrived in very good cosmetic condition but both drivers were frozen. Nobody's fault, just the nature of vintage Polk drivers with depredated adhesive and the impacts form shipping. $110 later with a pair of Polk drivers and I have an expensive pair of vintage Polk bookshelf speakers. Was it worth it? I'm on the fence but I will never sell them.

So I have come to the conclusion I'm going to make a pair of Monitor 10's from the ground up, essentially ending up with a brand new pair, made to a standard far beyond Polk's original mass produced product, ending up with a pair of Polk "prototypes" before the bean counters got their hands on them and strip the craftsmanship and quality to something they can make money on...

So the theme is a speaker that looks like the original but made from quality materials, excellent craftsmanship, attention to detail, even the details you can't see but certainly can hear. A pair of speakers that only a devoted Polk aficionado could appreciate.

I'm an amateur furniture maker so I am confident I can make a great looking pair of cases and a bit of a renaissance man but in no way an expert on electronics. My intensions are to use original Polk parts when practical, update the drivers, and maybe test a few ideas along the way.

I'm starting this thread not just to inform the world of my progress but to hopefully have you chime in and keep me from doing something silly. I'll post pictures and even include some of the data I have mined that I'm using as my guide.

So here we go. Let me start by showing you what I have already acquired in the next few posts.

William

willwilly

So I have been scanning eBay and have found some parts that are a good base for my project. I picked up this pair of Polk 10 drivers. They appear to be an early version and will make a good pair to update.
Unfortunately the seller thought you could wrap some bubble wrap around them and stuff them in a USPS bag and not get damaged.
I found another single driver of the same vintage to replace the board.

willwilly

willwilly

Now if money was not object, I would call up Polk a buy four replacement drivers for my speaker project but I'm going to take a risk and try a set of Dayton drives that are less than half the cost. I may regret this put it is an easy fix if these turn out to be a bad choice.

I have seen where some have replaced Polk drivers with these and say they are just as good if not better but the result is always subjective. If any of you have a pair of drivers that I could do a side to side comparison, I'm interested in buy for a reasonable price.


I also bought a pair of Dayton 8 ohm shielded tweeters but I have reconsidered using the these and have ordered a pair of new SL2000 Polk tweeters. This way I know this was Polk's initial intent and won't have any surprises.

deucekazoo

Good luck with the project. I also toyed with the idea of making my own but by the time you get all the drivers and parts, it was cheaper to pick up a pair to mod. What will you make the boxes out of. I always wanted to use birch ply for mine. Still might when I want to change the look of my M7s. I am in the process of updating the x-overs so you will want to do the same. Update all the caps and also the resistors. You can reuse the coils. Have fun.

willwilly

Dayton Audio DC160-8 6-1/2" Classic Woofer
Part # 295-305
https://www.parts-express.com/dayton-audio-dc160-8-6-1-2-classic-woofer--295-305

Of course these go on sale right after buying a pair...

DSkip

You aren't building Monitor 10's anymore. They also will not be made beyond the mass-produced standard of the original Monitor 10's if they use inferior/inappropriate drivers.

willwilly

Here is the Polk Monitor Schematic I am following as of now. I have asked tech support at Parts-Express to comment on recommendations to modify the crossovers to better compensate for the use of the Dayton drivers. I'll post what they have to say.

K_M

willwilly wrote: »

I have seen where some have replaced Polk drivers with these and say they are just as good if not better but the result is always subjective. If any of you have a pair of drivers that I could do a side to side comparison, I'm interested in buy for a reasonable price.
I also bought a pair of Dayton 8 ohm shielded tweeters but I have reconsidered using the these and have ordered a pair of new SL2000 Polk tweeters. This way I know this was Polk's initial intent and won't have any surprises.

You may get the original intent, but the SL2000 tweeter in all honesty, is not a great tweeter. It has some issues, with smoothness of sound caused by a peak around 12-13 khz.

Not horrible, mind you, but much better can be found for far less money.

Polk also has replacement tweeters that are better sounding, that remove the issues of the SL2000.

willwilly

I have seen the sl3000 is the typical upgrade that requires minor tweeking of the crossover. If you were forced to suggest a better tweeter for less money what do you have in mind? Remember I'm greenfield construction here so I can go with any configuration.

Nightfall

RDO-194s and original Polk midwoofers

willwilly

That's what I bought, RDO-194's...

westmassguy

The Dayton Classic woofers are decent, but are not even close to the original MW6500 or MW6503 woofer's T/S parameters. The SL2000 tweeters are god-awful.
Go with the RDO-194-1s, or modify the Crossovers for the RDO-198-1s. Unfortunately, the crossovers you have are early, and appear to be made for Peerless Tweeters, not the later SL1000 or SL2000.

F1nut

The Monitor 7's are a far better speaker than the 10's could ever hope to be. As for your project, stick with the original Polk drivers. Nothing better than doped paper, not mention the surrounds are unlike any others. In fact, you can't buy after market replacements to this day.

willwilly

I can't see how polk 7's can be significantly better than the 10's. They are essentially the same speaker with one less driver. You will have to explain that one to me.
I have bought RDO-194's and if I had four Polk MW6504's, I would use them.

The crossovers are being completely rebuilt with Sonia caps and mills resitors...

F1nut

The 7's don't suffer the inherent problem of having the mid-drivers next to each other.

F1nut

You must have 100 posts before you can sell anything here and it must be listed in the Classified section.

willwilly

Just recieved my eBay PS's. I need to add some sound dampening material to the cage and they will be ready to install.

F1nut

Oh well, I tried.

willwilly

deucekazoo wrote: »

Good luck with the project. I also toyed with the idea of making my own but by the time you get all the drivers and parts, it was cheaper to pick up a pair to mod. What will you make the boxes out of. I always wanted to use birch ply for mine. Still might when I want to change the look of my M7s. I am in the process of updating the x-overs so you will want to do the same. Update all the caps and also the resistors. You can reuse the coils. Have fun.

I had a large walnut tree fall in the woods four years ago. I was cutting it up for Firewood and found the log was nearly all heartwood and worth milling. I had it cut up in 4 and 8 quarter planks, quarter saw which gave me 6" planks. So this will be used for the body. The back will be birch Baltic plywood, the front will be the same laminated with black mat vinyl sheet. I have started making my router templates for the components. I know this is way overboard for functionality but form is very important for this project as well as function, just as important.

Veneered plywood is an excellent choice, even MDF. Very stable.

Let me know how your project goes...

willwilly

And yes, I'm updating my crossovers as well. Sonicap and Mills components, following the schematic I posted earlier.
Also using new 194 tweeters.

Nightfall

The later versions of RTA-12s are not at all like Monitor 10s. They roll off the side by side midwoofers at different frequencies to help avoid lobing with far more complex crossovers. This is why they are mirror imaged (L/R specific). They are also time aligned unlike any other vintage Polks.

DSkip

Plywood is a bad choice. Realize that wood has resonance and you are introducing completely new ones to the design of the speaker. It will throw off the entire voicing of the speaker.

When you started this thread, I was rather excited to see it come to fruition. However, as more details come out, I can't help but feel an overwhelming sense of disappointment for the end result. I truly wish you the best, but you are flying in the face of a design created by professionals that already has a inherent design flaw that wasn't fully realized until after the fact.

I think you will enjoy the speakers once completed, but they could be so much better if more care was taken in your choices. I am glad to see you moving to original woofers for the design.

Nightfall

Putting drivers side by side playing the same spectrum of frequencies.

DSkip

They're great rock out or background speakers. Tonally they are awesome. It's the stereophonic attributes that are flawed.

F1nut

rmpolk, that's a good explaination of the differences and spot on the money. My post was brief as I had hoped the OP would take it upon himself to investigate further, which obviously didn't happen.

So yes, the inherent flaw of side by side mids is called lobing, which means the imagining is smeared. Of course, the 7's don't have that issue and it was addressed in the Model (RTA/Monitor) 11's as you noted, which you also noted correctly as being very good sounding speakers, way better than the 10's.

willwilly, as DSkip noted plywood is a poor choice unless it's Baltic Birch, but even then MDF is a more inert and uniform product, which is why almost all speaker cabinets are made from it. Furthermore, using different materials for the cabinet walls is simply a bad idea.

DSkip

Even hdf could be used if layered and would be even more inert, but again that would change the tonality of the speaker. The Rosso Fiorentino speakers are built with HDF and sound superb, but they were designed with that material In place. I'd stick with mdf as mentioned above.

Sorry will if this comes across as bandwaggoning; I only wanted to expound on that topic a little more.

willwilly

Dskip, I will concur with your recommendation to stick with Polk original drivers and have abandoned the Dayton classic woofers and going with MW6503's, 194 tweeters and updated drivers with the most accepted brand of caps and resistors.

I'm curious why baltic plywood is a bad choice. I'll accept using different cabinet components could change the resonance of the air chambers, but can you elaborate on what attribute of plywood, or any other material that is different than the low density partial board laminated with vinyl shelf paper that Polk used would create a deficit in sound quality? What makes MDF a highly accepted speaker cabinet material? Or is it simply cheap and easy to work with?
Baltic plywood is not your typical dog house building material. It's construction results in absolutely no voids in the laminates, offers great stability and durability.
Also, isn't the poly batting suppose to reduce the effects of the cabinet resonating?
Or is it the fact that anything different than what was originally used during testing would change the end result. To that point: I am confident the resonate quality of the M10 prototype cabinet was tested, but the consistency of the cabinet material throughout the years of production was almost assuredly inconsistent and not considered, with cost being the motivating factor.
I can only respond to your disappointment with this, understand what the goal of this project is... I'm making a pair of Monitor 10's using the most accepted electronic component recipe, original Polk components, and actual wood in the cabinets. I'm not creating a test bed for improving a supposed flaw in the M10 design.
I am not an audiophile and quite frankly I have no idea what folks mean when they speak of lobing, good imaging or having a tighter bass. I know what I like and I'm limited in my experience with a wide range of high quality speakers.
So when you say your disappointed in my choices, make some suggestions, tell us you found to work, that is what this thread is all about.
I like monitor 10's and want to own my first pair. I just decided to make my own and take pride in the fact that I created a pair of great sounding speakers. I guess I could have just as easily made a pair of JDL'S but I didn't fall in love with a pair of those when I was 18.
Maybe my next pair will be M7's and we can chat about that process.

Great conversation...

willwilly

Dskip, One thought that has crossed my mind from your post, maybe some baffling behind the drivers that will not effect the performance of the PR but reduces the "cross contamination" of the two drivers? I just don't know enough about air/sound movement through a channel or chamber to get the desired result.

Nightfall

Maybe this will help?

http://www.diyaudio.com/forums/multi-way/45379-lobbing-what-laymans-terms.html

You dont know what imaging is? Imaging is the entire point of the stereophonic experience my good man. Otherwise you might as well be listening to mono from a single speaker.

http://forums.audioreview.com/home-theater-video/what-does-soundstage-imaging-exactly-mean-9713.html

willwilly

Yes, I don't know what imaging means. That certainly doesn't mean I'm tone deaf. I didn't realize this forum was for only the most discriminating audio geeks. I'm ignorant of the terms and experience of listening to 1000's of speakers. Just trying to share my project and maybe learn something from people that know far more than most need to know about speakers.