Refurbishing a Monitor 7A

jimbo1421

DaveOrAstroDave wrote: »

Hello there,

Wow, it looks like you're doing exactly what I just did, right down to the parts selection!

Well then, either we're both right or both wrong! How does your first one sound?

DaveOrAstroDave wrote: »

The only difference is I had to buy a new inductor too. Since you're using 10w resistors, I wouldn't worry so much about heat.. they're made to handle twice the power, so they shouldn't heat up as much to begin with, plus the added surface area means they'll dissipate heat faster.

Also, yes, you are correct about the capacitors and resistors not having a polarity that you have to respect. Either way should work fine.

I didn't think to dynamat my pair of 7A's, but I did use Moretite caulking cord to seal the drivers to the cabinets, as recommended in a few other threads. You might want to give it a try

As for future upgrades, I was thinking of splitting the crossover network and add a second pair of terminals so the speakers can be bi-wired, but I'm skeptical about what kind of difference it would make...

Anyway, good luck with the refurbishing project! As for me, I've still got one more speaker to go.

I will be using rope caulk (Moretite equal) to seat the drivers. Both the caulk and Dynamat Extreme worked well on my Monitor 10s.

Thanks,

Jim

kcoc321

Jimbo, I am curious, when you replaced the inductor, did you match it or upgrade it?

Either way, did it sound better?

I have heard that replacing the Inductors does not make much difference.

I have been considering upgrading mine to foils...wondering if it makes a difference.

DaveOrAstroDave

jimbo1421 wrote: »

Well then, either we're both right or both wrong! How does your first one sound?

It sounds great to me! So far I've tested it with the Police album Synchronicity and with Herbert von Karajan's earlier performance of The Planets. The drums in Synchronicity sound fantastic! Over all, tight punchy bass, clear mids and highs. The Planets sounds great as well, though the recording is definitely showing its age.

Admittedly, it took me a while to become reaccustomed to having accurate treble... the Sony speakers from my bookshelf system have both a low-tweeter and a high-tweeter for some reason, which overemphasizes the highs beyond belief. The Polks definitely have a much more balanced sound.

jimbo1421 wrote: »

I will be using rope caulk (Moretite equal) to seat the drivers. Both the caulk and Dynamat Extreme worked well on my Monitor 10s.

Look at me, telling people things they already know
Would you say the Dynamat makes a big difference? I might have to give it a try...

Best regards,
Dave

jimbo1421

kcoc321 wrote: »

Jimbo, I am curious, when you replaced the inductor, did you match it or upgrade it?

Either way, did it sound better?

I have heard that replacing the Inductors does not make much difference.

I have been considering upgrading mine to foils...wondering if it makes a difference.

That was DaveOrAstroDave who replaced the inductor. I left mine alone since it had no apparent damage.

Jim

jimbo1421

DaveOrAstroDave wrote: »

It sounds great to me! So far I've tested it with the Police album Synchronicity and with Herbert von Karajan's earlier performance of The Planets. The drums in Synchronicity sound fantastic! Over all, tight punchy bass, clear mids and highs. The Planets sounds great as well, though the recording is definitely showing its age.

Admittedly, it took me a while to become reaccustomed to having accurate treble... the Sony speakers from my bookshelf system have both a low-tweeter and a high-tweeter for some reason, which overemphasizes the highs beyond belief. The Polks definitely have a much more balanced sound.



Look at me, telling people things they already know
Would you say the Dynamat makes a big difference? I might have to give it a try...

Best regards,
Dave

Hey Dave,

I reseated the drivers with rope caulk and Dynamatted the baskets at the same time so I can't sort out the relative improved sound from the two different tweaks. Since I am doing both tweaks plus the crossover on the 7As I will be even more in the dark about what improves what. I have another set of Monitor 10s that are untouched. I think I will make those tweaks on them one at a time just to see.

Cheers,
Jim

hearingimpared

jimbo1421 wrote: »

Hey Dave,

I reseated the drivers with rope caulk and Dynamatted the baskets at the same time so I can't sort out the relative improved sound from the two different tweaks. Since I am doing both tweaks plus the crossover on the 7As I will be even more in the dark about what improves what. I have another set of Monitor 10s that are untouched. I think I will make those tweaks on them one at a time just to see.

Cheers,
Jim

These types of tweaks have a culmulative effect so you should notice a big difference if you did together.

jimbo1421

And they sound sweet.

The crossover rebuild went smoothly after you guys answered my questions (thanks a bunch). I got some spade terminals from Radio Shack for the speaker connections, but I think they are a little large. They fit snugly enough since there was still some solder on the male ends, but have some play side to side. I will try another electronics store next week for the right size.

I used rope caulk (Moretite equal) for all the drivers and PR, but left the terminal cup seal in place since it was in good shape.

The tweeter that I toasted a bit when desoldering the leads sounds OK. I gave the pair of 7As a high frequency workout with an old mono LP of Jascha Heifetz playing a Bach solo violin partita. Switching the balance all the way left and right, sometimes I think the toasted tweeter sounds a little worse, sometimes not. Sometimes I hear a bit of high frequency dissonance when both speakers are playing that same mono track. But this is subtle enough that it could be a room effect or something in the audio sources which, for sure, are not audiophile quality.

For a bass test, I tried "I'm Lucky" from Joan Armatrading's Walk Under Ladders LP. The opening notes can shake the house on a bigger system, but they were still quite satisfying on the 7As. Right now I am listening to Yo Yo Ma's Obrigado Brazil and it is just lovely.

The Monitor 7As are quite a bit more forgiving of audio source problems than my Monitor 10s , and Lord knows my sources need a lot of forgiveness (or a VPI RCM).

I will break in the new components over the next week or so and let you all know how it goes and post some pics once they are developed.

Thanks for all your help.

Regards,
Jim

jimbo1421

Hello,

Last August I rebuilt the crossovers in these Monitor 7As but have grown increasingly dissatisfied with the high frequencies. These have Peerless tweeters; one had some white powdery oxidation on the inside, the other I toasted with a desoldering iron. So yesterday I decided to swap out the tweeters with a pair of Monitor 10As that I bought last August. These tweeters look very similar, black faceplate and inverted V leads, but have "Made in U.S.A." stickers. They look just like Skrol's. They sound a whole lot better. Brighter, more detail, without harshness. So my question is: are these USA Peerless an exact replacement or do I need to modify the crossover in any way.

Regards,

Jim

Left pic is the original pair, right looks like my replacement.

ben62670

If you want to send me the stock unit, and the after market unit I can test them to see if they will play nice with the stock XO.
Ben

jimbo1421

Hi Ben, thanks for your offer. I don't think these are after market tweeters; they were pulled from Monitor 10As.

Jim

jimbo1421

I just got off the phone with Polk CS. The two Peerless tweeter types are interchangeable. I also realized this morning that one reason the USA Peerless sound so much better is that I had the originals hooked up out of phase. There is a red insulating washer under the positive terminal which I had ignored. D'oh!

Tony M

I just reread this thread and might have missed the answer.

Do the Ebay tweeters sound good enough to use instead of RDO's for the real old series of Polks?

Outfitter03

The vintage Peerless Tweeters can be purchased on this forum through the classifieds or from Ebay. These are no longer manufactured but "rescued" from old, damaged speakers that are parted out. If you are looking for a pair I would post an add on this forum in the wanted classifieds.

There are several forum members that are experienced in both testing these out before selling and doing bullet proof packaging for shipping. They also pop up time to time on ebay and as with anything on ebay it is seller related on the quality of product and packaging.

Good luck in your search. I believe you should be able to find some within 30 days, maybe faster.