Monitor 10a crossover upgrade

Rev. Hayes

This has been a very helpful thread!

I confirmed my Sonic Craft order today. Going entirely sonicap and mills. Whew! in one fell swoop I more than doubled the "cost" of my speakers. I sure hope it sounds worth it.

Either way I'm looking forward to the experiment.

Thanks to all who went before me and helped to spread this disease.

HB27

Once you get your appropriate values of the upgrade parts there's not a lot to stray from here.
Just remember "RDO, Mills, and Sonicaps" and not much else actually. Not being a smart arse but they're proven cost effective replacements for Polk and many other speaker "updates".
I also prefer the "Peerless" tweeters when working properly. It's the vintage Polk Monitor sound that originally got and has kept my attention. I do like the RDO for the later model speakers over the rest of the SL tweeters. Lots of nice ways to revive a classic speaker.

Rev. Hayes

I've got the Peerless and I plan on keeping them

I'm sure it will be great HB27. Besides, with such nice components to solder now I can justify an iron upgrade too!!! (now I just have to explain to the wife why we won't be buying a new couch anytime soon... pray for me;))

HB27

My prayers are with ya Rev. Bliss and harmony at home are important. Unless a nice piece of gear or pair of speakers become available cheap. Then the prayers come in handy. LOL! Best of luck guys.

cristo

Just redid my crossovers yesterday in my Polk 10a speakers. The old caps were not
very well matched - 12ufs were 13 - 16, and the 34ufs were 38 and 39 on my meter.
Used Sonicraft 12ufs - all 4 were between 12.4 and 12.5, and Solen 33ufs - both were
33.5, and Mills 5W 2.5 and 2.7 resistors. Turns out I didn't need to remove any drivers
to get to the crossover, just pull it out from the back panel. The caps were all bigger
than the originals, and the resistors were smaller than the original, but everything fit ok
in the end. I also took out my "upgrade" SL1000 tweeters and put the original US Peerless
ones back in.
My wife and I both think the speakers sound better now listening to music.
I used the Stereophile test cd3 to check frequency response and re-adjust my Soundcraftsmen
Graphic EQ (I know, EQ's and tone controls are a no-no, but there are some nasty room effects
that I need to tame).
The Peerless have a more extended less peaky upper register than the SL1000s, and they
sound cleaner playing the treble warble tones than the SL1000s.

Face

Enjoy!

Rev. Hayes

Woke up and did the first crossover upgrade for my Monitor 10's. I decided to wait on the second so a friend and I can do some comparison listening with mono recordings. (I have three monitor 10's so I'm gonna hook them up to a Niles speaker selector and see if he can tell the difference )

Also, how did y'all deal with the real estate issue of using 2 17uf caps in place of the 34uf? I currently have them on long leads but was thinking of getting longer screws for the board mount and gluing them to the bottom of the PCB.

Other ideas?

cristo

I used a single Solen 33uf since they should be good enough for a low pass filter,
and used Sonicaps for the two 12uf caps.

Rev. Hayes

So after some reading I see that most folks think the sonicap Gen I's need 350 hours to fully burn in. I would really like to do a serious side by side by side comparison between the modded and un modded speakers so I must wait and play music constantly for a week (the HORROR ).

However I most certainly will do the other crossover to match so my question is :

Is there and easy way to burn in the other set of caps without a fancy machine or installing them in a crossover. I would just like them to match once I do install.

HB27

That 350 hour figure is for complete burn in.
You'll get the major sound difference after about 15-25 hours. They'll still settle in the more you play them but you can do an a/b mono test and get the general sound quality difference you want for the test.

Rev. Hayes

HB27 wrote: »

That 350 hour figure is for complete burn in.
You'll get the major sound difference after about 15-25 hours. They'll still settle in the more you play them but you can do an a/b mono test and get the general sound quality difference you want for the test.

Cool

First thing after work tomorrow then!!!

Thanks HB27, that's just what I wanted to hear:)

Rev. Hayes

All done!

The most challenging bit was figuring out the best way to mount the two 17uf caps in place of that tiny 34uf that was stock. The solution I came up with was to use long bolts with a series of nuts to lock the PBC higher up. 1 1/2" bolts did the trick and threaded in nicely with the stock spacer nuts. I then mounted the caps on the underside of the board.

You can see here that it did the trick (and looks pretty cool too;)):

As stated in an earlier post I did one of the speakers last week and then did a little test with a few friends. listening to a mono copy of The Animals "Animalism" everyone managed to pick out the modified speaker as the one they preferred. When pressed to say why the most common reply was "I dunno, that one just sounds prettier."

My impression was that the highs were seriously smoothed out presenting a far more realistic sound... cymbals sounded like they had weight and weren't as "splashy"

Bass was noticeably tightened up and cleaner as well. I hadn't even noticed how much "one note bass" I was getting until i listened to the two side by side.

Most impressive to me was the deeper sound-stage and greater detail. I mean I wasn't falling into a concert hall or anything but the reverb effect on certain instruments was far more like what I hear at a show.

This jumped out at me particularly while listening to Al Green's "Call Me." I kept hearing this drum noise that I hadnt' really noticed before and I kept thinking "what is that?" It almost sounded like someone was playing a tom about the same time the snare was hit. Of course then I slapped myself because it's a sound I know very well from the world of live music. It was the snare. the actual drum not just the snap of the ballchain which is almost all you hear in so many recordings of that instrument. Anyway... very cool.

All in all I am very happy with the result. Looking at this project from a cost/benefit view it's hard to say if I will ever do this with my Lsi9's. But the experience of getting that down and dirty with my crossovers was a lot of fun and a very rewarding project.

HB27

You haven't heard anything yet. The complete burn in will leave you wondering how you ever lived without the rebuild on those.
Nice write up and now sit back and listen. Every day you'll hear something new from familiar recordings.