Monitor 5A's sound dull/veiled and I think I found out why.

Hofy

When I rebuilt the crossovers in the Monitor 5A's last year one of the caps and one of the resistors did not match the schematics. Instead of the 34uF and 6.2Ohm parts mine had 27uF and 2.5Ohm. I asked what I should replace them with and the consensuses was to replace with like values. Even after the replacement and break in period, the speakers still sounded dull and lifeless. This winter I stumbled upon a pair of Monitor 4 with Peerless. I decided to swap out the tweeters to find out if that made a difference. It did not. Next I swapped out the woofers. Still no difference. There just so happen to be a pair of crossovers on fleaBay that where built the same year as my speakers so I ordered them. The serial number and grease pen markings inside both confirm Monitor 5A. However, the one cap is 34uF and the resistor is 6.2Ohm. I installed them last night and the sound is an improvement. It makes one wonder what was going on at Polk on May 26, 1982. Office party? Ran out of the correct parts? A worker who just didnt care?

The original crossovers.


The replacements i just got.

Polkaguy58

At the risk of ruffling purist's feathers, the next time you have a few bucks burning a hole in your pocket, buy a pair of 5 Jr. X-overs and slip them in there.
I did as an experiment and liked the sound much better than stock.

pkquat

I'm no expert, but on the pdf cataloging all the polk speakers the very early 5A's appear to have 6.2 Ohm resistor. Its a little blurry but it looks like 6.2. The cap also has LP5 written on it. This would suggest there are more out there like this. Are yours early 5A's with the paper on the baskets and velco to hold on the grills? This could explain things, but I would think more people would have discovered this by now. My only guess is maybe if you have an early Denmark Peerless, Polk used some that had a different nominal resistance early on. If both the cap and resistor are on the highpass circuit that could be the case. What were the values before you rebuilt the crossovers?

xschop

If the resistors are in parallel, you have to use the RT formula to get the true value.
On my 2nd set of modded 5jr crossovers, I found that the Old Polk specs are wrong for their stated crossover frequencies, @1500 as opposed to 3K. That's probably why they sound fantastic in the Early Monitor 5's as Polkaguy has discovered. They sound fantastic in my modded TMM's as well.

Hofy

My Monitor 5A's are dated May 26 1982 on both the drivers and crossovers. The Peerless are USA made. The replacement crossovers with the 34uF and 6.2ohm are January 1982.

Hofy

Polkaguy58 wrote: »

At the risk of ruffling purist's feathers, the next time you have a few bucks burning a hole in your pocket, buy a pair of 5 Jr. X-overs and slip them in there.
I did as an experiment and liked the sound much better than stock.

5jr as in the ported model or the ones with the 6 1/2 inch passive?

westmassguy

The resistors are NOT in parallel. The outside resistor is in series with the tweeter. The inner one is in series with the shunt inductor.
The 6.8 ohm resistors were used for the Peerless Models. The 2.5 ohm resistors were used with the SL1000 tweeters. That's been my observation anyway.

Polkaguy58

Hofy wrote: »

Polkaguy58 wrote: »

At the risk of ruffling purist's feathers, the next time you have a few bucks burning a hole in your pocket, buy a pair of 5 Jr. X-overs and slip them in there.
I did as an experiment and liked the sound much better than stock.

5jr as in the ported model or the ones with the 6 1/2 inch passive?

I'm talking about the 5 Jr passives.
I know it sounds goofy, but I had 2 pair of Jr's and a pair of 5's and was just curious as to how they would sound.
You don't have to mod anything, so I figured what the hell.
I liked the way the mids perked up a little and to me the bass had a bit more punch to it.
I liked it enough to leave it that way.

pkquat

I forgot to attach the pdf link.

cdn.vanillaforums.com/polkaudio.vanillaforums.com/attachments/4/7/5/0/2/53135.pdf

I have original 1983 5A's with USA peerless tweeters and 27µF caps. Oddly on the pictures I have the 2.5 Ohm resistor is not showing. I also have a spare set of 1983 crossovers that have 27µF caps and the 2.5 Ohm resistor. both crossovers match the 198?-1984 series shown in the pdf. Dull and veil are not words I would use to describe the sound. At worst they could be considered a little warm. The mystery continues. It makes me curious to see what that crossover combination would sound like, or where the difference lies.

Polkaguy58 wrote: »

At the risk of ruffling purist's feathers, the next time you have a few bucks burning a hole in your pocket, buy a pair of 5 Jr. X-overs and slip them in there.
I did as an experiment and liked the sound much better than stock.

I think this only works for 5B models with the SL2000 tweeter or later, but I could be wrong.

Polkaguy58

In the world of heretic speaker defilers.............there is no right or wrong. (heh heh)

pkquat

Polkaguy58 wrote: »

In the world of heretic speaker defilers.............there is no right or wrong. (heh heh)

lol true. Well then, your results may vary.

xschop

If Polk was entitled to toss in anything at their disposal, why not us.

Hofy

I have original 1983 5A's with USA peerless tweeters and 27µF caps. Oddly on the pictures I have the 2.5 Ohm resistor is not showing. I also have a spare set of 1983 crossovers that have 27µF caps and the 2.5 Ohm resistor. both crossovers match the 198?-1984 series shown in the pdf. Dull and veil are not words I would use to describe the sound. At worst they could be considered a little warm. The mystery continues. It makes me curious to see what that crossover combination would sound like,

Interesting. The replacement crossovers are dated Jan 1982 with the 34uF and 6.2ohm. The original crossovers that came with the speakers are dated May 1982 with the 27uF and 2.5 ohm. I have to get the speakers back on their stands for a better listening comparison. My Monitor 5jr (ported) and Monitor 4 Peerless both sound so much more open and detailed.

Nightfall

xschop wrote: »

If Polk was entitled to toss in anything at their disposal, why not us.

There are several reasons why Hofy's crossovers could have had the wrong parts in them. It wasn't as if Polk thought it okay to just throw whatever caps in their crossovers regardless of uF.

xschop

Disgruntled employee?

Polkaguy58

We used to call new guitars that came into the shop messed up "Monday Morning Specials"

Hofy

OK, the mystery continues. I got the 5A's up on the stands with the Monitor 4's on top. While the sound of the 5A's did improve with the replacement crossovers, it is not much. I have switched both the MW6500 drivers and the Peerless tweeters with the 4's . I am at a loss as to why these speakers sound so dull/vailed/lifeless compared to the 4's.
Does anyone have any ideas?

xschop

Reverse the leads on the tweeter and see if that helps.

Hofy

xschop wrote: »

Reverse the leads on the tweeter and see if that helps.

All that did was take it out of phase.

However, since I had the speakers open I decided to try something. I swapped the crossovers between the Monitor 4's and the Monitor 5A's. Now we are getting somewhere! The 5A's opened up. A little lacking in the bass but not bad. The 4's became dull and lifeless along with no bass.

skrol

pkquat wrote: »

I forgot to attach the pdf link.

cdn.vanillaforums.com/polkaudio.vanillaforums.com/attachments/4/7/5/0/2/53135.pdf

Cool, that's my document!

xschop

On one of my Early 5jr crossovers (no board), the factory had the tweeter leads soldered backwards, but it's leads were hooked up correctly when I opened them up. I figured the assembly line made mistake but just switched leads correctly before sending it out.

I guess a set of old Polks is like a box of chocolates.....you never know what your gonna get...hehe.

CGTIII

@xschop - I'll second that about chocolates. I just found a 10A with a 4-Ohm driver instead of the 8-Ohm it should have! Shrimp Creole anyone?

pkquat

Hofy wrote: »

However, since I had the speakers open I decided to try something. I swapped the crossovers between the Monitor 4's and the Monitor 5A's. Now we are getting somewhere! The 5A's opened up. A little lacking in the bass but not bad. The 4's became dull and lifeless along with no bass.

First, great to learn they are sounding better. They may sound even better tipped back at I think 6 degrees depending on your listening height compared to the speakers. The bass is a little lacking in the 5's. The location of the poly-fil can make a difference. The consensus is to have one roll behind the tweeter and the other roll behind the MW. There were some 1983 vintage that had the lower roll behind the PR from the factory from what I gather. IMO the bass rolls off a little later but steeper with the poly-fil behind the PR, and earlier but slower behind the MW. The bass was a little more felt with it behind the MW. The PR used also made a minor difference.

It appears you may have a bad set of crossovers. I am am still not sure what vintage 5A you have. Pictures or reference to what vintage they are in the linked pdf would be great. Pictures would be best since it sounds like they were made during a changeover time period when things could have been mixed and matched. 5A crossovers do appear on ebay from time to time, or someone here may have some. It may be worth it to try a set before rebuilding them.

What are the component values for the 4A peerless crossover? Any pictures?

This is an interesting mystery. I am surprised there is not more crossover documentation on some of the early models since people have rebuilt them. Did originals from Polk around 1983 get lost?

skrol wrote: »

Cool, that's my document!

Thank you for making that!! I hope it is being kept somewhere as a living document with updates. I thought there was a more of a fixed location link a year or two ago.

Hofy

pkquat wrote: »

Hofy wrote: »

However, since I had the speakers open I decided to try something. I swapped the crossovers between the Monitor 4's and the Monitor 5A's. Now we are getting somewhere! The 5A's opened up. A little lacking in the bass but not bad. The 4's became dull and lifeless along with no bass.

pkquat wrote: »

First, great to learn they are sounding better. They may sound even better tipped back at I think 6 degrees depending on your listening height compared to the speakers. The bass is a little lacking in the 5's. The location of the poly-fil can make a difference. The consensus is to have one roll behind the tweeter and the other roll behind the MW. There were some 1983 vintage that had the lower roll behind the PR from the factory from what I gather. IMO the bass rolls off a little later but steeper with the poly-fil behind the PR, and earlier but slower behind the MW. The bass was a little more felt with it behind the MW. The PR used also made a minor difference.

Yes, I have done the tilt back. It did not change much. The poly-fil in my 5A's had one roll behind the tweeter and one behind PR. I moved that up when I first got them.

pkquat wrote: »

It appears you may have a bad set of crossovers. I am am still not sure what vintage 5A you have. Pictures or reference to what vintage they are in the linked pdf would be great. Pictures would be best since it sounds like they were made during a changeover time period when things could have been mixed and matched. 5A crossovers do appear on ebay from time to time, or someone here may have some. It may be worth it to try a set before rebuilding them.

My 5A are May 26,1982. Both the drivers and original crossovers have that date. They still had all driver connections soldered. I rebuilt the originals last year. I have already tried a set from eBay. They are dated Jan 1982 and had 34uF instead of the 27uF cap and 6.2Ohm resistor instead of the 2.5ohm that my originals had.

pkquat wrote: »

What are the component values for the 4A peerless crossover? Any pictures?

I will get some more pics up soon, Skrol is welcome to add any of them to his pdf document. The Monitor 4 speakers are just 4 not 4A. They are dated Dec 1982. I do not know the value of the crossover inductors but the larger one appears to be thinner than what you see in a monitor 5 or 7. The smaller inductor is about twice the size of the small one in a 5 or 7. There are no resistors and the single cap is 5.8uF.

pkquat wrote: »

This is an interesting mystery. I am surprised there is not more crossover documentation on some of the early models since people have rebuilt them. Did originals from Polk around 1983 get lost?

With the improvements I heard yesterday I am going to try dropping in the crossovers from my 5jr ported speakers. I am wondering if the 5A crossovers are crossing over at 1500Hz and not 3000Hz? I know for a fact that the 5jr I have crossover at 3000Hz.

Polkaguy58

pkquat wrote: »

Hofy wrote: »

However, since I had the speakers open I decided to try something. I swapped the crossovers between the Monitor 4's and the Monitor 5A's. Now we are getting somewhere! The 5A's opened up. A little lacking in the bass but not bad. The 4's became dull and lifeless along with no bass.

First, great to learn they are sounding better. They may sound even better tipped back at I think 6 degrees depending on your listening height compared to the speakers. The bass is a little lacking in the 5's. The location of the poly-fil can make a difference. The consensus is to have one roll behind the tweeter and the other roll behind the MW. There were some 1983 vintage that had the lower roll behind the PR from the factory from what I gather. IMO the bass rolls off a little later but steeper with the poly-fil behind the PR, and earlier but slower behind the MW. The bass was a little more felt with it behind the MW. The PR used also made a minor difference.

It appears you may have a bad set of crossovers. I am am still not sure what vintage 5A you have. Pictures or reference to what vintage they are in the linked pdf would be great. Pictures would be best since it sounds like they were made during a changeover time period when things could have been mixed and matched. 5A crossovers do appear on ebay from time to time, or someone here may have some. It may be worth it to try a set before rebuilding them.

What are the component values for the 4A peerless crossover? Any pictures?

This is an interesting mystery. I am surprised there is not more crossover documentation on some of the early models since people have rebuilt them. Did originals from Polk around 1983 get lost?

skrol wrote: »

Cool, that's my document!

Thank you for making that!! I hope it is being kept somewhere as a living document with updates. I thought there was a more of a fixed location link a year or two ago.

If they do sound better with the 5Jr crossovers, please tell the others that I'm not crazy........(heh heh)

Hofy

Polkaguy58 wrote: »

pkquat wrote: »

If they do sound better with the 5Jr crossovers, please tell the others that I'm not crazy........(heh heh)

I just tried it on one speaker with the 5jr crossover. Yes it does wake it up! However it does appear I have lost some bass on it. I will swap out the cross over on the other one later and report.

pkquat

Polkaguy58 wrote: »

If they do sound better with the 5Jr crossovers, please tell the others that I'm not crazy........(heh heh)

Hofy wrote: »

I just tried it on one speaker with the 5jr crossover. Yes it does wake it up! However it does appear I have lost some bass on it. I will swap out the cross over on the other one later and report.

Good to hear it worked out. My main concern was the the tweeters are different, possibly significantly, between 5jr's and 5A's. It could be fine, or only bad sounding, but I worry it could possibly damage a tweeter. That was my main concern. I love those peerless tweeters. They may not be on par these days for super critical listening and the finest of detail, but IMO they are one of the best sounding for extended periods with a lot of detail, plus pleasing to my ears.

If I ever get a set of 5's or 7's with SL/RDO tweeters, I will try the 5jr swap for sure.

agfrost

It's not unheard of for Polk to get "creative" in installing crossovers at the factory.

Polkaguy58

I wasn't so worried about any loss of low end bass, because I had another pair of 5Jr's for the rear channels and that way I could cross the sub to match all 4 speakers, rather than have it overlapping on the 5's

Hofy

For today's experiment I dropped a MW6502 in with the 5jr crossover. We have bass again!

xschop

From a an online crossover calculator and an Android app, I came up with @1.5k crossover for the 5jr unless I was doing something wrong.
If the tweeter cannot go that low then it will miss those frequencies. That document with the 3k crossover reference is what I first saw when making my modded 5jr's (ported)