Monitor 7B Help - Mods & Repairs

benjaminlea

Hello from Australia! Long time reader first time posting in the forum. I’d love some help with my 7B’s.

Their history is unknown but I purchased them about 6 months ago from eBay for $100aud from someone who had planned to use them as “outdoor party speakers”. They are in very good condition for their age, vinyl is ok, a couple of missing pegs, all drivers working. I’ve recovered the grills and found some peerless tweeters for sale and need some advice.


Is it really worth the investment? I haven’t done crossovers yet but plan to. Here in Aus sadly, it’s so expensive to ship everything and none of the caps I’ve read that are recommended are available for purchase here.

The tweeters I’ve found are $90usd with $50usd shipping to Aus.. I don’t mind paying for them but can anyone who’s done the swap chime in and tell me honestly, was it worth it?

From what I’ve read the crossover upgrade is significant, something I’m planning to do very soon.

I’ll post a few pics of my 7’s and the tweeters for sale.

Thanks in advance!

Gardenstater

Congratulations! Your 7B's are a later edition than mine, which are early 7B's. Mine came with the Peerless tweeters #7514??79 and my MW6500s are not rabbeted into the front baffle and neither is my Passive Radiator. I think it's interesting that your Passive is rabbeted but the MW is not! Also you have the later grille style where the polk audio badge is on the enclosure and the grille doesn't go all the way to the bottom. You probably have the different style grill pegs as well. I don't think that color fabric is original as I have only ever seen black. I think the #5514s from 1983 there look great. I believe but am not 100% certain, that 5514's may have a slightly lower impedance than 7514's. I'm still trying to confirm that for sure. When I swapped out my 7514's for some 5514's temporarily, they were a bit on the bright side and the DCR is about 1 Ohm lower.

I would be interested in knowing the details of your crossover network stock components as I have always wondered if Polk made any changes at all when going from the Peerless to the SL1000 that you have. If they DID make changes you might want to reverse those changes in going to the Peerless. Let me know what components you have and we can compare. Pics would be good too.

PS: Oh sorry....as to your question of whether or not it is worth the investment in light of the higher shipping charges.......I'd say probably so. You will do the mods in dribs and drabs to lessen the $ pain and you will be pretty amazed at how they perk up during the process and you will have us to guide you in the process so you don't waste money with any missteps!

benjaminlea

Thanks for your input! Yeah I changed the grill to a beautiful linen cloth partly to update the look and partly to knock some of the highs off the tweeter. I read when I got them, the tweeter was harsh but personally I don’t hear it.

To me the tweeters are fairly bright but not fatiguing and I liken it more to them just being on the very clear side, haha. When I have the grills on, those highs a knockdown just enough and when I want to bring back that richness, it’s simple enough to remove the grill covers.

That’s the other reason I’m hesitant about making the change to peerless. If it’s not going to be such a dramatic change, and if I will benefit more from upgrading the crossovers then I might do that first but I realise those tweeters do not come up online very often.

If I decide to keep those tweeters do I run the risk of any damage by removing individual screws and replacing or painting them? Due to their age there is some rust on them and I know it’s only aesthetic but it’s something I’d like to clean up.

I was quoted $99 per hour of labour, basically, $99 per cross over to upgrade (locally by a company that specialises in restores) but I still have to supply the parts. By the time I ship the parts to Australia it’s almost the same kind of money as replacing just the tweeters.

If I do pull them apart even to just glue the magnets, I will definitely take some more photos for you! While I’m gluing the magnets, is it worth replacing the baffling or anything else while I have them out? During the crossover upgrade I plan to request all of the speaker wire internally point-to-point be changed as well as binding posts.

Gardenstater

benjaminlea wrote: »

Thanks for your input! Yeah I changed the grill to a beautiful linen cloth partly to update the look and partly to knock some of the highs off the tweeter. I read when I got them, the tweeter was harsh but personally I don’t hear it.

To me the tweeters are fairly bright but not fatiguing and I liken it more to them just being on the very clear side, haha. When I have the grills on, those highs a knockdown just enough and when I want to bring back that richness, it’s simple enough to remove the grill covers.

That’s the other reason I’m hesitant about making the change to peerless. If it’s not going to be such a dramatic change, and if I will benefit more from upgrading the crossovers then I might do that first but I realise those tweeters do not come up online very often.

If I decide to keep those tweeters do I run the risk of any damage by removing individual screws and replacing or painting them? Due to their age there is some rust on them and I know it’s only aesthetic but it’s something I’d like to clean up.

I was quoted $99 per hour of labour, basically, $99 per cross over to upgrade (locally by a company that specialises in restores) but I still have to supply the parts. By the time I ship the parts to Australia it’s almost the same kind of money as replacing just the tweeters.

If I do pull them apart even to just glue the magnets, I will definitely take some more photos for you! While I’m gluing the magnets, is it worth replacing the baffling or anything else while I have them out? During the crossover upgrade I plan to request all of the speaker wire internally point-to-point be changed as well as binding posts.

I can't tell you for sure whether the Peerless will sound better than the SL1000s at least not from personal experience of never having heard the latter. From what I have heard others say here, the Peerless are superior, but in what ways specifically I don't know.

Again, you need to find out if there are any crossover changes made by Polk by comparing to mine. If you don't reverse those changes the speaker may sound off because the voicing will be wrong.

I wouldn't mess with the polyfill as long as it is in original condition and rolled up behind the tweeter and MW. You want to make sure it hasn't fallen down to the passive area. It would be a good time to Dynamat Xtreme the baskets and BlackHole5 behind the MW's. It's up to your budget I suppose. $99 Australian = $77 US pretty steep for soldering work in my opinion. It is not hard to do yourself. As far as rewiring, the devil is in the details as far as how much improvement you see. I went higher awg and I went with Cardas Litz and Neotech solid UPOCC for the Cardas Binding Posts and tweeters and MW.

Personally I wouldn't mess with removing those button head socket head screws for the tweeter magnets. If I did I would only remove one at a time and replace with a Black Oxide finish one. Don't paint it won't last.

benjaminlea

Thanks so much that’s really good advice. Maybe for now I’ll pass on those tweeters since I really have no idea whether there will be a sonic upgrade or not at least to my ears anyway. I don’t mind paying for an upgrade that on paper will definitely improve my listening experience but maybe that money is better spent on other components at the minute.

I did see a lot of posts about the passive radiator so I think I’ll do that as well. Thank you for the advice on the cost of soldering work. I wasn’t sure if this was overpriced or not as I watched a few videos and it seems fairly simple but I understand that I’m paying for somebody’s experience less the work to be done.

Is there anything I need to know when purchasing caps? I will buy the sonic caps and Mills resistors… I’m a little unsure about deleting the fuse and having to do something with the resistors… Can you shed a little bit of light on this for me since you seem extremely experienced!?

It’s purely a 2.1 music system, I have a vintage Velodyne sub for some light lows and I’m overall extremely happy with the performance of everything but, I know upgrades can be done so of course I wanna venture down that road, haha.

Gardenstater

benjaminlea wrote: »

Thanks so much that’s really good advice. Maybe for now I’ll pass on those tweeters since I really have no idea whether there will be a sonic upgrade or not at least to my ears anyway. I don’t mind paying for an upgrade that on paper will definitely improve my listening experience but maybe that money is better spent on other components at the minute.

I did see a lot of posts about the passive radiator so I think I’ll do that as well. Thank you for the advice on the cost of soldering work. I wasn’t sure if this was overpriced or not as I watched a few videos and it seems fairly simple but I understand that I’m paying for somebody’s experience less the work to be done.

Is there anything I need to know when purchasing caps? I will buy the sonic caps and Mills resistors… I’m a little unsure about deleting the fuse and having to do something with the resistors… Can you shed a little bit of light on this for me since you seem extremely experienced!?

It’s purely a 2.1 music system, I have a vintage Velodyne sub for some light lows and I’m overall extremely happy with the performance of everything but, I know upgrades can be done so of course I wanna venture down that road, haha.

Yeah you most definitely want to do the Dynamat on the Passive as well. I went with the Sonicaps and Vishay/Mills and was extremely happy. If your XO's are like mine you will need a 34uF and a 12uF. You should pay a little extra to have the caps matched to each other. It will be interesting to see what resistor value you have. I'd be surprised if Polk didn't make any changes for the SL1000.

As far as removing the fuse, that is definitely the route that 90% take. I left mine in because I have an old vintage amplifier that I don't completely trust, but changing the wire that goes into the fuseholder to Cardas Litz wasn't for the faint of heart. If you have plenty of power so you won't be clipping and you trust the condition of your amp I'd remove the fuse. Just remember that the nominal Cold Resistance of a 1 amp Littelfuse fuse is spec'd as 190mOhms. That's cold so when you are playing music it will be higher. I don't know how much higher. So I'd definitely raise the tweeter resistor value by 0.2Ohms if I were going to remove that fuse.

F1nut

Get the Peerless tweeters and get rid of those nasty SL1000's. They will be a noticeable improvement. $99.00AU/ $77.00US is very reasonable for the crossover work. I wouldn't touch them for less than $100.00US each.

Upgrading the crossovers is definitely worthwhile, just don't use Solen, Dayton or Bennic.

As for removing the fuse, what are you using for power and how loud are you likely to play them? Also, something to have looked at are the lead wires coming off the fuse holder. If they are badly oxidized definitely get rid of the fuse at which point you'll want to compensate for the resistance of the fuse/fuse holder. Your tech can measure that and bump up the high frequency circuit resistor.

Can't say I'm a fan of your grill cloth color.

rooftop59

Nice snag and welcome to the forum! I owned a pair of M5s with the 8 inch passive and peerless tweets, and those tweets are far superior to yours, which I also owned at one point. definitely worth it!

I like the grills, matches your cabinet and is a nice blend of retro and contemporary!

One question no one has asked: are you driving those with a crown amp??? If so, you are not realizing their full capability...

benjaminlea

F1nut wrote: »

Get the Peerless tweeters and get rid of those nasty SL1000's. They will be a noticeable improvement. $99.00AU/ $77.00US is very reasonable for the crossover work. I wouldn't touch them for less than $100.00US each.

Upgrading the crossovers is definitely worthwhile, just don't use Solen, Dayton or Bennic.

As for removing the fuse, what are you using for power and how loud are you likely to play them? Also, something to have looked at are the lead wires coming off the fuse holder. If they are badly oxidized definitely get rid of the fuse at which point you'll want to compensate for the resistance of the fuse/fuse holder. Your tech can measure that and bump up the high frequency circuit resistor.

Can't say I'm a fan of your grill cloth color.

Haha, will I have to do much work to the XO’s for those tweeters as someone pointed out? I feel $90 per XO is reasonable too, good to get a feel for what people think is good value though.

Using a Crown XLS 1002 the new DriveCore series. It’s only dialed up a little over half way and I probably play up to 85% of that when I’m getting really enthusiastic, haha.

I’ll only buy Sonic and Mills as everyone is suggesting! So I appreciate that tip to stay away from other brands.

I haven’t looked inside but I assume the leads are oxidised. They are as old as I am so it’s to be expected.

It’s ok, you don’t have to like the grills. But we can agree they are amazing speakers and still be friends.

😂

benjaminlea

rooftop59 wrote: »

Nice snag and welcome to the forum! I owned a pair of M5s with the 8 inch passive and peerless tweets, and those tweets are far superior to yours, which I also owned at one point. definitely worth it!

I like the grills, matches your cabinet and is a nice blend of retro and contemporary!

One question no one has asked: are you driving those with a crown amp??? If so, you are not realizing their full capability...

Ugh I’m so torn about the tweeters…

Thank you! My house is modern contemporary and I like the old new blend. I’ll aim at some point to re-do the cabinets in walnut or the like. But for now, changing the cloth is cheap and a nice little upgrade to my overall space.

Haha, yes. Crown. Cringe and cry all you want.. the DriceCore series as insanity. They are wildly clean and have more power than required. I always want to be able to turn something down and not be able to not turn it up.

Go check Z Reviews on YouTube if you’re interested in why I chose that amp. Very in-depth, detailed and technical review.

I also realise ya’ll like muscle cars so to speak and this is a Tesla by comparison and I’m ok with that! Haha.

New and old can blend 🙈

I also grabbed it on sale for $600aud and it puts out 215wpc. Way more then required for my 7B’s.

I’ve ran vintage before with a NAD amp and I was impressed too. In Aus we have some standard consumer law warranty that is ambiguous at best. It states warranty for anything is ‘a reasonable period of time’ minimum 3 years.

So when buying, I factored that in too. Also, Crown is owned and this amp designed by Harmon Kardon. I didn’t throw the baby out with the bath water.. completely.

☺️

Clipdat

benjaminlea wrote: »

Go check Z Reviews on YouTube

LOL! Z reviews..

F1nut

If you really want to hear what your speakers are capable of get an audio grade amp after you get the crossovers done.

benjaminlea

F1nut wrote: »

If you really want to hear what your speakers are capable of get an audio grade amp after you get the crossovers done.

Please define said “audio grade amp” 😂

benjaminlea

Clipdat wrote: »

benjaminlea wrote: »

Go check Z Reviews on YouTube

LOL! Z reviews..

Haha.. oops. Upset someone already. 🤷🏼‍♂️

Waiting for the hate to come about the Loki too. Lel.

F1nut

WTH is a Loki?

F1nut

benjaminlea wrote: »

F1nut wrote: »

If you really want to hear what your speakers are capable of get an audio grade amp after you get the crossovers done.

Please define said “audio grade amp” 😂

The ones made for home audio, not pro audio.

benjaminlea

F1nut wrote: »

benjaminlea wrote: »

F1nut wrote: »

If you really want to hear what your speakers are capable of get an audio grade amp after you get the crossovers done.

Please define said “audio grade amp” 😂

The ones made for home audio, not pro audio.

Ohh cute - audio for home. Gotcha. 🥲

benjaminlea

F1nut wrote: »

WTH is a Loki?

Clipdat

Can you post the rest of this photo? I want to see if you have hair anywhere on your body.

Gardenstater

benjaminlea wrote: »

Haha, will I have to do much work to the XO’s for those tweeters as someone pointed out? I feel $90 per XO is reasonable too, good to get a feel for what people think is good value though.

Just to make sure it's clear I wasn't saying that *if* Polk made any changes in going from the Peerless to SL1000, that it would mean that the crossover was more complex in number of components, only that it would be good to know if they did make any changes or not, prior to updating the crossovers, as well as what tweeters you are going to use ultimately. That way you order the correct components and only have to do the job once. Makes sense? *If* they did change anything it would probably only be the value of the tweeter resistor.

These are my early 7B crossovers (1979 vintage, 7514 Peerless tweeters, MW6500) after I modded them. I kept the original inductors. The values of the caps (12uF and 34uF) and resistors (2.7 Ohm and 4.5 Ohms) were kept the same as original. Fuseblock was retained and rewired with Cardas 11.5awg litz.

benjaminlea

Clipdat wrote: »

Can you post the rest of this photo? I want to see if you have hair anywhere on your body.

Ummm.

benjaminlea

Gardenstater wrote: »

benjaminlea wrote: »

Haha, will I have to do much work to the XO’s for those tweeters as someone pointed out? I feel $90 per XO is reasonable too, good to get a feel for what people think is good value though.

Just to make sure it's clear I wasn't saying that *if* Polk made any changes in going from the Peerless to SL1000, that it would mean that the crossover was more complex in number of components, only that it would be good to know if they did make any changes or not, prior to updating the crossovers, as well as what tweeters you are going to use ultimately. That way you order the correct components and only have to do the job once. Makes sense? *If* they did change anything it would probably only be the value of the tweeter resistor.

Ahhh ok. I’ll pull the XO out some time over the weekend and drop some pics in here and maybe you can advise me?

Tbh, I’m just supplying components and requesting the job be complete so it would be good to know before taking my XO’s to get upgraded so I can supply the requisite components and don’t encounter any surprises!

The seller gave me a bit of a discount on the peerless @$75usd for the pair and I only have to pay $80usd for shipping and import taxes. What a good deal..

🤦🏼‍♂️

F1nut

benjaminlea wrote: »

F1nut wrote: »

benjaminlea wrote: »

F1nut wrote: »

If you really want to hear what your speakers are capable of get an audio grade amp after you get the crossovers done.

Please define said “audio grade amp” 😂

The ones made for home audio, not pro audio.

Ohh cute - audio for home. Gotcha. 🥲

Judging by your gear you have a lot to learn about what makes for great audio. If you want to learn what that takes we're here to help. However, if you think you've already got that figured out just know that you're mistaken. Think about it without letting your ego get in the way.

benjaminlea

Gardenstater wrote: »

These look so nice - well done. I think I’ll follow your lead.. if I do delete the fuse what resistor would change? As in, what values would shift?

benjaminlea

F1nut wrote: »

Judging by your gear you have a lot to learn about what makes for great audio. If you want to learn what that takes we're here to help. However, if you think you've already got that figured out just know that you're mistaken. Think about it without letting your ego get in the way.

Ok, thanks. ☺️

Gardenstater

I think I would raise the main tweeter resistor from 4.5 Ohms to 4.7 Ohms. In my case. Whatever the case, I would raise the value by 0.2 Ohms. Another thing is we don't even know for sure if Polk kept the MW6500 in your speakers. Besides going from the Peerless to SL1000 they may have changed the MW as well. It will be interesting to find out. Your speakers are kind of a missing link.

benjaminlea

Gardenstater wrote: »

I think I would raise the main tweeter resistor from 4.5 Ohms to 4.7 Ohms. In my case. We don't even know for sure if Polk kept the MW6500 in your speakers. Besides going from the Peerless to SL1000 they may have changed the MW as well.

Ah right, let me do some disassembling over the weekend and come back with a bit more info.

Greatly appreciate your support.

👊🏻

Gardenstater

If you are decided on the tweeters, my advice would be to pop them in for a listening and comparative test, prior to making the decision on what resistors values to go with for the XO upgrade. Maybe you will think they are brighter, maybe less. Listen a while and get a feel for them. Do some whitenoise spectrum analyzer graphs with a smartphone app, for the SL1000 and then with the Peerless 5514's. Those 1983s would be about when Polk made the changeover to SL1000 so if they tried to match the impedance and other thiele small parameters you may not hear much of a voicing difference.

dmeffert

Hi Benjaminlea. Welcome to the forum. I am also a relative newcomer here and have very similar 7B speakers but mine still have the Peerless tweeters. F1nut and Lawdogg recently helped me with the mods on mine and I have noticed some very good results.
One thing that was definitely an issue with mine was there was corrosion on the leads to the fuse holder, and on several of the wires to the drivers from the crossover where they were soldered to the board, so I did the fuse bypass and de-soldered all of the wires to the drivers and clipped off about an inch on each one to get to bright copper, and re soldered them back to the boards. It would be worth checking while you are doing the work. I also used the 4.7 ohm Mills resistors in place of the stock 4.5 ohm. I also used the Dynamat, which really made a difference. Lastly, I changed the binding posts and used some very nice ones from Zu Audio that work really well but requires some modifications to the old holes to work.
Could you please tell me what the cloth is you used, and is it specifically for speaker grills, and what kind of stands are those?

benjaminlea

dmeffert wrote: »

I also used the 4.7 ohm Mills resistors in place of the stock 4.5 ohm. I also used the Dynamat, which really made a difference. Lastly, I changed the binding posts and used some very nice ones from Zu Audio that work really well but requires some modifications to the old holes to work.
Could you please tell me what the cloth is you used, and is it specifically for speaker grills, and what kind of stands are those?

I only pulled my XO out today to briefly have a look but wasn’t able to verify any corrosion to the fuse.

I won’t be doing the work but wanted to see what work might be required.

Did you use 4.7ohm for both resistors?

Ahh it’s just some fine linen cloth from a fabric store. My tweeters are a tad bright so it helps to cut them down a bit but I really only wanted them for the look. I remove the covers when I listen to music and the stands were a $10 eBay find haha.

Here what my XO look like.

dmeffert

The corrosion is on the wires connected to the fuse holder inside the crossover itself. There is a ton of hot glue covering those wires and the ones connected to the binding posts. Without removing all of that you won't be able to tell what's lurking beneath it.