Pioneer HPM-100 Recapping Walkthrough

[Copa1934]

The 0.15 uF caps are a bit pricey. I see there's no others in that value for less, though.

How about 027-406 0.47 uF plus 027-402 0.22 uF in series for 0.1499 uF at $1.61 the pair instead, maybe?

Can someone explain to me how this works? How exactly does the math work on this?

 

[avguytx]

Caps in parallel increase the value. Caps in series decrease the value. There are crossover calculators out there that will do it for you and there is also a mathematical formula for it. But I just use the ones online if it ever comes to that point.

 

[Radni]

Hi guys ,
Not realising earlier about this great thread on restoration of Pioneer HPM-100 , I had started another thread on this subject seeking help. It is at the following link:

http://www.audiokarma.org/forums/showthread.php?p=5635437&posted=1#post5635437

Ideally these two threads should be merged , but I am giving this link ( above ) so any one visittng this thread is also guided to the other one.
But I do like to complement xoaphexox for lovely walkthrough and pictures and parts lsit , source , prices and off course the write up !

 

[Rob.]

Good info here. THANKS

 

[XJR100]

Just Another HPM-100 was recapped

Some notes:
- I expected, that electrolytic capacitor (0.15uF) will by dryes, but measured it was within normal tolerance - 20% for electrolytic caps. So, suppose not a big impact on sound if it changed to film capacitor.
- bad things: after measuring speaker I've found, that there is problem with the drivers: no matter what you do with crossover - they will not match, there is always hole on freq.response, seemes that it is the age.
- film capacitors which are there: replacing them to better ones gives positive changes - sound becomes more smooth and some "acid" disappeares.
- LF driver: it supposed to sound from low to 3kHz - covering all freqs which responsible for vocals, but unfortunetly due to the age do not play more than 1.5K
- attenuators: if it is in "0" it gives +6dB on 3K and +8dB on 8K, so I've found some position (if remember "-5") to het more or less flat responce on 1m on tweeter axis. Another thing - response changs a lot if microphone is of-axis: looks unpredictable if compare with other speakers, so HPM-100 require right position and right angle for listener.
- all the values of capacitors left same as specified: 4.4uF, 3.0uF, 0.15uF
- I've found very positive change in LF after replcing original coil to aircore foil coil 0.56mH (original is 0.6) and also changed wiries to LF to better ones - original were really thin.

Some pictures will follow...

 

[XJR100]

Just Another HPM-100 was recapped

Some notes:
- I expected, that electrolytic capacitor (0.15uF) will by dryes, but measured and it was within normal tolerance - 20% for electrolytic caps. So, suppose not a big impact on sound if it changed to film capacitor.
- bad things: after measuring speakers I've found, that there is problem with the drivers: no matter what you do with crossover - they will not match, there is always hole on freq.response, seemes that it is the age.
- film capacitors which are there: replacing them to better ones gives positive changes - sound becomes more smooth and some "acid" disappeares.
- LF driver: it supposed to sound from low to 3kHz - covering all freqs which responsible for vocals, but unfortunetly due to the age do not play more than 1.5K
- attenuators: if it is in "0" it gives +6dB on 3K and +8dB on 8K, so I've found some position (if remember "-5") to het more or less flat responce on 1m on tweeter axis. Another thing - response changs a lot if microphone is of-axis: looks unpredictable if compare with other speakers, so HPM-100 require right position and right angle for listener.
- all the values of capacitors left same as specified: 4.4uF, 3.0uF, 0.15uF
- I've found very positive change in LF after replcing original coil to aircore foil coil 0.56mH (original is 0.6) and also changed wiries to LF to better ones - original were really thin.

Parts list (all components - Mundorf):
3uF: 2pcs 1.5uF Mundorf MCap 400V - 2x2,79€
http://www.audiohobby.eu/en/mcap400/2235-capacitor-mkp-mundorf-mcap-400-vdc-15-uf.html
4,4uF: 2pcs 2.2uF Mundorf MCap 400V - 2x3.19€
http://www.audiohobby.eu/en/mcap400/2240-capacitor-mkp-mundorf-mcap-400-vdc-22-uf.html
0.15uF: 1pcs 0.15uF Mundorf MCap 630V - 1x2,59€
http://www.audiohobby.eu/en/mcap630/2256-capacitor-mkp-mundorf-mcap-630-vdc-015-uf.html
10 Ohm: 5W MOX - 1x0.79€
http://www.audiohobby.eu/en/mr5/2556-resistor-mox-mundorf-5w-10-ohm-metal-oxide.html
0.6mH for LF: 0.56mH CFC16 1x16,90€
http://www.audiohobby.eu/en/cfc16/1654-coil-mundorf-m-coil-cf-cfc16-056-mh-17-mm.html
Wires: DH-Labs SH-18: 1m of red and 1m of black - 2x3€
http://www.audiohobby.eu/en/hook-up...nt-for-loudspeaker-internal-wiring-black.html
-------
Total is ~38€ for one speaker.

With that small investment serios changes in sound: much more pleasant, not so "acid" and better soundstage.

 

[Rob.]

Good info for future.

 

[onwardjames]

Sorry, but I don't understand this "age" thing you keep speaking about.

Are you saying that the drivers are losing range due to their age?

Why have I NEVER heard this on AK??

 

[XJR100]

Sorry, but I don't understand this "age" thing you keep speaking about.

Take a look on graph: it is nearfield of bass driver. Hardly belive that Pioneer engineeres made crossover with specified 3K cross with mid with that response. I think 20-30y ago they performed differently.

I suppose the problem is related to driver surroundings - it does not let to moove cone as the new ones, thus after aging it have different flexibility. Very common problem with rubber surrounds - simply it dryes, but HPM-100 on bass driver have paper surrounds, but with some sticky compound on it, and mid-driver for me look like matherial is not paper and totally dried.

 

[Rob.]

I suppose the problem is related to driver surroundings - it does not let to moove cone as the new ones, thus after aging it have different flexibility. Very common problem with rubber surrounds - simply it dryes, but HPM-100 on bass driver have paper surrounds, but with some sticky compound on it, and mid-driver for me look like matherial is not paper and totally dried.

HPM-100 use cloth surrounds with dope.

 

[starquest52]

A lot of good info in this thread.

 

[XJR100]

HPM-100 use cloth surrounds with dope.

I've ispected mid - the surround is very hard, does not look like it have any dope or it is dryed. What other owners can say about their HPM-100 mids surrounds?

 

[Skylab]

The surround on the midrange is treated cloth, but it's not treated the same way as the woofer. But it shouldn't be - the travel required on the midrange driver is very minimal, due to the crossover point.

 

[XJR100]

That's right, but still looks like they not as good as new drivers - you see "holes" of freq.response in the places where they should not be.

I've done measurements of all drivers and tried to play with crossover in LspCAD - no use, as drivers do not match each other -no matter what you put in the schematics there is still "holes" on response.

 

[jojo0416]

Finally I am able to catch up with this project and ordered my parts, including the binding post arriving this coming Friday.

2pcs 027-700 Audiocap PPT Theta 0.01uF 600V Film/Foil Capacitor (to place in parallel with 3.0uf)
2pcs 027-710 Audiocap PPT Theta 0.10uF 600V Film/Foil Capacitor (to place in parallel with 4.3uf)

Can someone confirm that all I have to do is solder these 2 caps in parallel with 4.3uf and 3.0uf as above? I just want to make sure and not make any mistake.

BTW, what does xoaphexox meant by

"That should not only give me the benefit of a bypass cap"; what is a bypass cap and what does it do to for HPM crossover,...sonics?

Thank you all great people.

Jojo

I 2nd that, thanks!

About to place an order for some .1uF AudioCaps to run in parallel with the Dayton 4.3uF's I mention in my original post. That should not only give me the benefit of a bypass cap but also give me the required 4.4uF crossover point.

Picking up some .01uF AudioCaps as well to bypass the 3.0uFs.

Can't leave well enough alone :scratch2:

 

[pognoot]

I haven't noticed any "holes" in the FR of my recapped HPM100s. Sure, they're still bright by design, but a gentle amount of EQing took care of that and I now have a satisfying set of vintage speakers to enjoy.

 

[jojo0416]

Hi Guys, I just got my parts, and will fix my speakers tonight. Unless somene tells me I am doing this wrong

2pcs 027-700 Audiocap PPT Theta 0.01uF 600V Film/Foil Capacitor (to place in parallel with 3.0uf)
2pcs 027-710 Audiocap PPT Theta 0.10uF 600V Film/Foil Capacitor (to place in parallel with 4.3uf)


Thanks!

 

[xoaphexox]

Hi Guys, I just got my parts, and will fix my speakers tonight. Unless somene tells me I am doing this wrong

2pcs 027-700 Audiocap PPT Theta 0.01uF 600V Film/Foil Capacitor (to place in parallel with 3.0uf)
2pcs 027-710 Audiocap PPT Theta 0.10uF 600V Film/Foil Capacitor (to place in parallel with 4.3uf)


Thanks!

You're right, just solder them in parallel and you will be good to go. The crossover points will match the stock crossovers and you will get the sonic benefit of a bypass capacitor as well. Good luck!

 

[jojo0416]

xoaphexox, I got it all done, and I really like the new binding post! :yes:

I do not exactly understand the purpose of the bypass capacitor but one thing I noticed was the tweeters were brigther (not a bad thing though) and I would say the bass frequency much lower because I can hear my room lights vibrating on the same volume as before

Thanks, I am happy to finally complete this small project.

 

[xoaphexox]

Great news. If things are too bright you can tone them down a bit with the trimmers at the top of the cabinet, I'm sure you know. Hope you enjoy them!