Pioneer HPM-100 Recapping Walkthrough

[DocMartens]

Inspired by this excellent thread I recapped a pair of HPM-100s last week. Especially I liked the suggestion to use wire clippers, scissors, or needlenose pliers to clip off the old components, I hadn't thought of that. As you say, the clipped leads just fall out after a little desoldering.

A few questions though:

I don't quite see how you could remove the wires from the woofer reaching through the speaker from the back of the speaker. There is room for your arm yes, but you are not able to see what your are doing. I guess you could could just follow the wires with your fingers when removing them, but how were you able to attach them to the woofer posts after the recap?

I managed to do the job without removing the wires from the super tweeter and the woofer. By putting a small clamp at the opening at the back of the speaker I was able to secure the crossover board when soldering in the new components.

When putting the crossover board back to the black plastic holder I was not able to put one of the screws in place, one of the new caps was in the way. I guess this is not a problem though, as there are three other screws plus the speaker posts to hold the board to the plastic holder?

 

[xoaphexox]

A few questions though:

I don't quite see how you could remove the wires from the woofer reaching through the speaker from the back of the speaker. There is room for your arm yes, but you are not able to see what your are doing. I guess you could could just follow the wires with your fingers when removing them, but how were you able to attach them to the woofer posts after the recap?

I was able to sufficiently feel around. Following the wires as you mention helps. The long skinny arms don't hurt either

When putting the crossover board back to the black plastic holder I was not able to put one of the screws in place, one of the new caps was in the way. I guess this is not a problem though, as there are three other screws plus the speaker posts to hold the board to the plastic holder?

I dont think that will matter much as long as you arent blasting them and it rattles. Maybe you could fill the hole with some epoxy to create a seal?

 

[sleddogman]

Four screws hold the woofer in and they're easily removed. As they're a ported cabinet, there's no gasket sealant. Just remove the woofer as it makes things a lot easier.

 

[DocMartens]

Four screws hold the woofer in and they're easily removed. As they're a ported cabinet, there's no gasket sealant. Just remove the woofer as it makes things a lot easier.

Yes, it makes things a lot easier for us who no longer have skinny arms!

 

[DocMartens]

When putting the crossover board back to the black plastic holder I was not able to put one of the screws in place, one of the new caps was in the way. I guess this is not a problem though, as there are three other screws plus the speaker posts to hold the board to the plastic holder?

I dont think that will matter much as long as you arent blasting them and it rattles. Maybe you could fill the hole with some epoxy to create a seal?

Yes, I guess I could use some expoxy, but then again this is no problem, really. But I am curious, am I the only HPM-100 recapper having trouble fitting that screw?

 

[Zilch]

Thetas

Yes, I guess I could use some expoxy, but then again this is no problem, really. But I am a curious, am I the only HPM-100 recapper having trouble fitting that screw?

I got it in, 1/4 turn at a time, using a small flat-blade screwdriver. Elevating the 4.3 uF to provide access is key.

Also, saved enough on the 0.15 uF to put in Theta bypass caps, which fit on the back of the board:

Measured values of components removed:

4.4 uF = 4.38, 4.50
3.0 uF = 3.07, 3.12
0.15 uf = 0.185, 0.190

Recommendation:

Add 0.01 uF Thetas across stock 4.4 uF and 3.0 uF
Replace 0.15 uF with 0.47 uF and 0.22 uF in series, as shown.

http://audiokarma.org/forums/showthread.php?p=1273846#post1273846

 

[Zilch]

Measured Voltage Drives:

 

[xoaphexox]

If I am reading that graph correctly, does that suggest to flatten the HPM-100 you should kick up 3kHz a notch?

 

[Zilch]

These measurements confirm what member Tripqzon found, and puzzled over, in an earlier thread.

I believe we've pretty much determined that HPM-100s are somewhat flatter off-axis. If you tame them on-axis by altering the crossover, you'll likely end up with a hole in that region from the normal listening position.

My frequency response measurements are here:

http://audiokarma.org/forums/showthread.php?p=1801956#post1801956

Ray's just now getting his measurement system back up and running, and may have some recommendations when he completes his analysis.

Once he's done, I'll post mine.... :yes:

 

[needforspeed]

I got it in, 1/4 turn at a time, using a small flat-blade screwdriver. Elevating the 4.3 uF to provide access is key.

Also, saved enough on the 0.15 uF to put in Theta bypass caps, which fit on the back of the board:

Measured values of components removed:

4.4 uF = 4.38, 4.50
3.0 uF = 3.07, 3.12
0.15 uf = 0.185, 0.190

Recommendation:

Add 0.01 uF Thetas across stock 4.4 uF and 3.0 uF
Replace 0.15 uF with 0.47 uF and 0.22 uF in series, as shown.

http://audiokarma.org/forums/showthread.php?p=1273846#post1273846

Zilch, Thanks for the work, And giving the Pioneer brethren another option. Also I forgot to give you the the resistors I have. An easy swap I'm guessing. The graph seems to show an improvement. I've read alot on the by-passing issue, And doing the tweeter seems to almost universal. I've seen even the M/R being done on some loudspeakers. What do you think about re-testing the speaker after C/O installation? A before/after may shed some more light on this system, I'm sure a fairly big change will take place as far as sound is concerned. New data may be needed to see if any other issues are out there(Tweeter change?) Again thanks. Robert

 

[Tripqzon]

As Zilch stated they are flatter off axis. What I have found from my measurements, which is also shown in the factory freq. response chart, is that they do suffer from roll-off above 12kHz when listened to in the off-axis position.

I did purchase a set of super tweeters used in the HPM-900's to try to lessen the roll-off but they did not do the trick. In fact there was no measureable difference that I could see and no audible difference as well.

Until a solution is found I listen off-axis and set the treble control up at 1:00 on my preamp to compensate for some of the roll-off above 12kHz and I enjoy the HPM-100's to a degree I have never enjoyed before.

I'll be watching this thread closely and share any info I may come across or try that works for me.

Paul

 

[Tripqzon]

How does the response look measured with a microphone and pink noise?

Paul

 

[Zilch]

How does the response look measured with a microphone and pink noise?

Link at #50, above.... :yes:

 

[dBfreak]

Confessions of a Copycat

Thanks for the mod info. An improvement in sound.

:yes:

 

[cgnman59]

Thanks for this thread! Very helpful. I'm now planning to recap my 100's. The crossover is the same as pictured in this thread. I've thought about trying to lower the crossover from the woofer to midrange from 3000Hz down to about 1500Hz. I've looked at PE's crossover chart. The question though: Is it really as easy as getting a cap of about 9.4uF and an inductor of 1.2mh or would it throw everything off on the rest of the crossover? Or am I missing this entirely? Yeah, as you can tell I'm not at all a tech. I've been in radio for over 30 years but strictly program and on-air!
The last thing I want to do is alter a crossover in a bad way so I'm prepared to just recap if the consensus is that its not worth it to try to lower the crossover. Thanks!

 

[Zilch]

The highpass filter on the midrange is single-pole, 4.4 uF. If you want to move it to 1.5 kHz, you'd double that, to 8.8 uF.

What you propose is a two-pole filter based upon the PE chart, which assumes an 8-Ohm impedance, not the case, apparently.

Look at the single-pole 3 kHz in the PE chart. It's 6.6 uF, 1.5 X the stock value.

Does that mean what you should use for two-pole is 3.1 uF and 0.4 mH from the 4.5 kHz line?

Well, maybe, but you're also changing the slope and phase. You have the requisite skill and measurement gear to competently redesign this crossover, right?

 

[Kegger]

Thanks for this thread! Very helpful. I'm now planning to recap my 100's. The crossover is the same as pictured in this thread. I've thought about trying to lower the crossover from the woofer to midrange from 3000Hz down to about 1500Hz. I've looked at PE's crossover chart. The question though: Is it really as easy as getting a cap of about 9.4uF and an inductor of 1.2mh or would it throw everything off on the rest of the crossover? Or am I missing this entirely? Yeah, as you can tell I'm not at all a tech. I've been in radio for over 30 years but strictly program and on-air!
The last thing I want to do is alter a crossover in a bad way so I'm prepared to just recap if the consensus is that its not worth it to try to lower the crossover. Thanks!

I have contemplated doing this same thing in the past, as I think lowering that woofer
to mid xover point would be a good thing, if I were trying this I'd shoot for starting by
changing the woofers coil to 1.2mh from .6mh and the mid cap from 4.4uf to 8.8uf an
try to get the parts as close to those values as can be.

It's an easy enough experiment to try, not very expensive and can be undone, go for it!

Like Zlich says the correct way to do it is with measurements, but I still think this is a
suitable starting point with a good chance of success and improvement if one feels the
need for improvement in there HPM's, I went quite a different route with mine.

 

[Zilch]

I went quite a different route with mine.

Heh, heh.

I'd leave the woofer inductor @ 0.6 mH. My measurements show a big ol' hole between 1 kHz and 3 kHz, and Ray heard the same thing in his listening tests.

Just stick a 4.3uF in parallel with the stock 4.4 uF and hear what happens, first.... :yes:

 

[Kegger]

Good points Zilch, and I don't want to dreail this here thread or turn it into HPM bashing, but
for me with the woofer producing what frequencies it can produce upto 3k an being that it is
a ported cabinet I find the backwave sound coming through the port at the higher frequencies
just doesn't work for me and that it does not sound very good. (I've tamed it with padding)

Now my thinking was, being as that 12" woofer is pretty much given up trying to produce much
above probably 1.5k anyway that trying to cut it off an hope the mid can make up for it is worth
experimenting, those mids will probably produce from 1.5k to 3k better then the woofer is so your
hole will probably be filled in or at least mitigated plus you'll get less unwanted port noise to boot.
(what I am getting at is bring the woofer back an let mid drivers do more of the lower mid-range)
(I don't see a problem with those mid-ranges being asked to produce down to 1.5k, not a stretch)

Again others find these HPM's a perfectly good sounding speaker and I have no problem with that,
but for me it just did not cut in stock form to be a keeper for me, so it's either mod or stash away.
(well early on I did some mods, then stashed away, then brought back out an did more mods now)

 

[Zilch]

That's why I added "First."

Nobody's measured the mid driver's response capability, to the best of my knowledge.

If it's too forward, then shut off the woofer lower to tame it, yes. It's also possible that an interference notch will develop at 1.5 kHz at certain listening axes. There's trouble already apparent at 30° and 60° in the published response.... :yes: