HPM 60, crossover rebuild vs active crossover

HowlerMonkey

Active Member
Hi All,

I have used this forum as a resource for a while now and I would like to contribute by starting a thread to document my experience with the HPM60's. I found a pair at my local Goodwill last year; paid around $75. After some minor maintenance I was able to get them going and have had fun with them these past few months. They are definitely forward speakers compared to other speakers that I have (CS Model Six, Boston A60, MA Bronze2...). They sound great with some music...they can misbehave with other...I can tell the crossover / tweeter design are the weak links....Before I got these speakers I was already making plans to embark in the dark universe of speaker kits and had my mind set on buying an active crossover to test drivers...I don't have the skills to build/restore a passive crossover, but I have some experience with active crossovers, EQing, mics, bi-amping...I am planning to buy a DBX 234 this fall and do some bi-amping on the HPM60s. Below is a link to a video when I tested the speakers for the first time.

 
A replacement of the old, probably electrolytic, capacitors in the old crossover should be your first move. If an examination of the drivers shows them to be in good order just replace those old capacitors with some audio grade poly caps. This is very easy to do in most cases, a simple soldering job. You can do it.
 
A replacement of the old, probably electrolytic, capacitors in the old crossover should be your first move. If an examination of the drivers shows them to be in good order just replace those old capacitors with some audio grade poly caps. This is very easy to do in most cases, a simple soldering job. You can do it.

I am up for the challenge and I will try that. I researched this forum and the internet last year and found the diagrams of the factory crossovers...I will look for equivalent replacements parts....That said I still think the factory crossover, crossover points and the tweeter/mid are not that great. I might "modify" one speaker and keep the other one as close to factory as possible.
 
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This post describes what I did when I got the speakers: (December 2016)
After inspection, it was clear that one speaker was in better shape than the other was. Both the cabinet and drivers of the “bad” speaker needed some TLC. The cabinet had a dent on the lower back corner, the woofer had a 3mm puncture in the dust cap, the tweeter had dimple in the dust cap. The midrange was the worst, it had had a small puncture in the paper cone. The tear was the shape and size of the edge of a thumb nail L..sad!. The super tweeter was clean.

The first thing I did was to disassemble all the drivers and dust off/clean everything the best I could.
I tested all drivers:

Woofer
25-737A, 27820
5.2 TO 5.4 OHMS
White is Red dot

Midrange
10-726A, SC 7823
6.3 to 6.4 ohms
Green is Red dot

Tweeter
45-711B 47823
5.9 to 6.1 ohms
Red is Positive

SuperTweeter
HP-015A-1, SX 7824
Yellow is Positive

I used double-sided tape to pull back the dimple of the tweeter. I searched for a used midrange driver on eBay. The drivers were going for $50-60 or so back then. I had just spent $70 on the speakers in total so I was not ready to pay $60 for a used midrange. I decided to research the cheapest way to fix a punctured paper cone. I followed these instructions to a tee.


The results were a bit crude but the midrange driver worked properly after the repair and I was now confident to test the speakers at louder volumes and decide if I was going to keep the HPM60s long term.

All drivers looked great on the “good” speaker so that one is untouched to this day.
 
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I obviously decided to keep the speakers and I am now ready to buy some drivers and play with the crossovers. The untouched speaker (see previous post) sounds better than the one I had to repair. Mostly noticeable in the midrange and high frequencies….Songs like Daft Punk-Within are painful to listen on the bad speaker… The first 60s of that song will show the limits of any good speaker nevertheless a repaired one.
I will be shopping on ebay this fall and I will be looking for both midrange and tweeter drivers hopefully in pairs. See you there!
I started working on the bad speaker first so I can learn with this one. I removed the crossover this week, I have the SWN-155-0 version.
 
HM, sounds like you have made some progress. Those caps on the xover don't look too bad.

Not sure replacing will change that "forward" sound much. New caps might even make them even more forward.

Have you tried turning down the HF controls to see whether you can get a less forward sound?

You should be able to cut both the mid and tweeter quite a bit. Super tweeter has no control! So if it is causing your problem, your only option would be to bi-amp and simply "push" the woofers harder via woofer amp volume control.

Regards,
Jerry
 
HM, sounds like you have made some progress. Those caps on the xover don't look too bad.

Not sure replacing will change that "forward" sound much. New caps might even make them even more forward.

Have you tried turning down the HF controls to see whether you can get a less forward sound?

You should be able to cut both the mid and tweeter quite a bit. Super tweeter has no control! So if it is causing your problem, your only option would be to bi-amp and simply "push" the woofers harder via woofer amp volume control.

Regards,
Jerry
Hi Jerry,

Yes I have the same feeling that switching caps will not make enough of a difference ...but I am willing to try it as a learning experience. These caps are 63V, 6uf and 3uf ....Maybe I can find caps with similar specs. (I will need to buy caps, a soldering kit and a six pack of beer.)

Regarding the controls in the back...I have turned the HIGH down and the MID up in both speakers and they have very little effect at the listening position that I use them. I have read posts online that say that the controls in the back rarely work. Not sure if the parts are rusted or what...I am planning to inspect them and test them this weekend.

I see bi or tri-amping in my near future with an active crossover. I already have a multichannel amp (Rotel 956-AX) and I think I can find a decent 3 way/4way analogue crossover on ebay. The only problem will be to cut the 12,000 Hz frequency for the super tweeter and keep the transformer. Few active crossovers cut that high so the supertweeter might need a passive filter and the transformer circuit. The goal of this thread will be to try both methods: a passive crossover rebuilt vs an active tri amp setup...I hope I don't break anything in the process...and if I do I will make sure I record it!
 
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Also, I should mention that I don't necessarily mind the "forward" nature of these speakers...I am more concerned with the "scratchy", high distortion highs that I get on certain songs...specially from the "bad" speaker. I think Pioneer has made an effort to present the sound in the best way they could while other manufacturers/speakers, like the CS Model Six that I am using for now, completely roll off some of the highs and just avoid dealing with that range of the sound...The CSM6 are very enjoyable speakers but I am also aware that I am missing some of the information in the songs whenever I play them.
 
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I made some progress this weekend: I tested the XO and every single driver independently. The crossover seems to work as intended, the attenuators also work fine. I used a tone generator app and (1) 30W channel from the Rotel Amp. I am sure some new XO caps could help but the "scratchy" high response that I was complaining about was coming from a bad tweeter driver. The tweeter driver will need to be replaced. I seems like they are going for $70+ on ebay...I also saw some "Pioneer copy tweeter" MT-4120 by Midwest Speaker Repair on Ebay....It looks like they use the castings of the 45-711s, they cost around the same price as the used original tweeter. Has anybody tried the MT-4120 before? I am leaning towards an original 45-711 but $70 is right at the limit of what I am willing to pay....Anything higher than $70 makes a SEAS dome tweeter a lot more attractive. ...Attached is my crude midrange repair that works fine for now :) and the "scratchy" tweeter. I will try to record some audio soon.
 

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I bought a tweeter driver 45-711B on Ebay for $70 plus shipping... (ouch!)...I tested it already and it works great. I also found an Active Crossover (Rane A23), for close to the same price of what I paid for the driver.. :) ....I am looking for capacitors for the passive crossovers now.
 
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I bought caps for the passive crossovers this week. Solen Caps at Parts Express. I ordered 3.0uf and 6.2uf Polycaps (6.0uf was not available) for the passive crossovers...I also ordered a 16uf to protect the tweeter in the active crossover setup.

Solen Caps 2.jpg
 
Was there a reason you did not replace the .3 uf cap and the 8 ohm resistor?
Hi, great question. I did not buy the parts for the Super Tweeter yet, first because of cost (I try no to spend more than $100-150 in hobbies each 30 day cycle....just to keep myself in check) and second because I was nervous to ruin a $15 dollar cap in my first rebuild.....I need to get my soldering skills up to speed and I was hoping to gain some confidence with the other caps first .....I will probably replace the 0.3uf cap eventually but I figure that I could work with the frequencies up to 12K first which are the ones I will immediately notice the improvement on....Regarding the resistor, I was not even considering replacing that one....my assumption was that resistors don't really go bad compared to caps ...I measured it to ~8ohms and that was good enough for me.....How much influence do you think a new resistor will have on the performance of the ST? what type of resistor should I replace it with?
 
It won't cost that much. I think I may have spent less than $40 for 6 Dayton Audio Grade Poly caps and two Dayton resistors. Before and after:IMG_0187.JPGOld Caps and resistor

IMG_0188.JPGNew caps and resistors. IMG_0204.JPGOriginal caps and resistors.
 
Thanks for sharing your pics....The $15 cap that I was referring to was the Solen silver series 0.3 uf cap thinking that I should stay within the Solen brand just because the other caps I already bought are also Solen and have maching voltage ratings...but since the Daytons are way cheaper and you have tried them already, I decided to order a couple of the Dayton 0.3caps and the 8 ohm resistors shown in your pics....(the rating does seem a bit low at 10W for the active setup but I will try)...I will add this purchase to the next billing cycle :)
 
For those thinking on a speaker/XO rebuild, this is what I have spent so far without counting the speakers purchase:
* (1) Original used tweeter 45-711B, ebay: $75
* 70W soldering kit, amazon: $39
* Midrange, tweeter caps, Solen, parts express: $20 ---for (2) crossovers
* Super tweeter, cap and resistor, Dayton, parts express: $8---for (2) crossovers
* New 5-way binding posts, Amazon, $12:---for (2) speakers

So far on the passive setup: $159 and the speakers are still down :(....I am glad I have other speakers on the bench while I wait

For the active setup I have spent:
* Rane 23S active crossover, ebay: $80
* Original SWN-155-0 crossover, ebay: $25-----I need this for parts, mainly the Super Tweeter circuit (transformer, inductor....)
* Super tweeter, cap and resistor, Dayton, parts express: $6---for (1) crossover (split shipping with above)
* Solen cap, (to protect the tweeter that I just bought for $75): $12 (split shipping with above)
* 1/4" to RCA cables, guitar center: $12

So far on the active setup: $135 (I have been using the active crossover combined with spare speakers for now...lots of fun....review to come)

I know this hobby makes no financial sense (very few hobbies do but that is a different story) and I could have bought some new speakers for $300....but what is the fun in that?
I am learning a lot in the process and I honestly believe that It will be hard to find a 3 way speaker & xovers setup that provides this much fun playing rock unless you move to the $300+ range.
Also, I am spending more money to explore both (avenues passive vs active) but you only have to pick one before you start....hopefully this thread will help somebody who is debating if they should rebuild their passive XOs.
 
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Finished the mod of one crossover today. It is not a beautiful job but everything works well.IMG_3222.JPG
I modified the binding posts also
IMG_3231.JPG .
I had to get creative.
IMG_3227.JPG IMG_3226.JPG
Learned a lot. Definetly some sound improvement compared to the original crossover. I recorded some audio. I will edit the video/audio files and upload them soon.
 
Next week I will design a terminal plate and a small circuit to test the active crossover (Rane A23). I plan to compare the HPM60 with active crossover vs. the HPM60 with the modified passive crossover. I will run this test at 90W bridged for the passive crossover vs 30W x 3 for the active setup.
IMG_3219.JPGIMG_3218.JPG
 
The terminal plate for the active setup is 90% completed.I just need to find a way to mount the capacitor for the tweeter portection. will have pictures soon.
 
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