Pioneer Early Version HPM-60 Project

[Kencat]

Thought I'ld start a new thread to document my HPM-60 project, since the "confusion" part is now over, with the fact that there were different designs of the HPM-60, over time, established. ( ref http://audiokarma.org/forums/showthread.php?t=45020
).

I'm going to document as much as I can, so that others who are looking for information, can find this thread while searching on the net. I find that there is a real lack of information available on the so-called WWW wrt to speakers. Do a search on the HPM-60....It sucks :thumbsdn:

So, here I go. I hope others on AK feel the same way, and offer their comments, corrections, knowledge, and for sure the witicisms and humour I've come to enjoy, to this thread.

Mine are the "earlier" version HPM-60 speaker, with the round woofer and midrange drivers. The tweeter is also a cone-style, which is not easy to see because of the grill (see pics attached). I assume the Supertweeter is the same on the later versions, but don't know for sure at this point.

I found the mid and tweeter drivers for sale on Ebay for this "Early" model. See below for the PNs. Pics attached.

Tweeter Part number 45-709F
Midrange Part number 10-719A

I will post more pics of the woofer after I've removed mine along with the part number info.

I can see already that this early woofer has a stamped steel basket. The later version speaker had a woofer with a "cast" basket design. The other obvious difference in the woofer is the surround. The early version - mine - has a foam surround; whereas, the later version had an accordian style surround, I THINK of treated cloth, but this needs to be verified.

I'll end here to keep this post short, but as I am writing, I am thinking that it was a great error (and deception) by Pioneer to have made such drastic changes to this model line without having given it a different model designation. The two different versions are COMPLETELY different speakers.

I am actually somewhat pissed off that what I purchased is not the HPM-60 that everyone raves about - the one that is the little brother of the hugely popular HPM-100. That one is the "later" version HPM-60 with the square cast-basket-woofer and midrange. I did not know that there were "different speakers within the same model designation" . Mine are the "pre-production" version, if you will, of the HPM-60 that most people see pics of and desire to own. From a collectors standpoint -historically and sonically- hopefully the "early" version has some merit.

I will attempt to give readers a good account of the hardware and design features of this EARLY version HPM-60 based on info that I have or can find, as well as my personal opinions of the "sound" of this speaker (after the surrounds are replaced ). Please look at my previous thread as shown above, because there are some excellent comments by fellow AKers about the sound differences between the two different designs. I will only be able to judge my "early versions" based on the other speakers that I have now.

More to come.

Ken C.

 

[Kencat]

I have my "new" early-version HPM-60s at home now after a 5 hr trip to get them.

So far I am impressed :yes: The cabs are fairly large for a 10" woofer speaker system - the woofers look kind of small actually- they are approx 13-3/4 "W x 24" H x 12-5/8" D. They weigh in at 38 lbs per the spec sheet. The cab wall thickness is a bit over 5/8".

These speakers have had a good life I think (since 1976 or so), based on the fact that the instruction sheets are still in good shape stapled to the back of the boxes. There are no nasty smashed in corners anywhere. The vinyl covering has some tears and chunks out of it here and there. Could be worse I think for having lived for almost 30 years.

I had to try them out, even though the woofer surrounds are 30% gone - had to, honest, couldn't resist....I was gentle

Surprised...big time....I did not expect the bass I heard. The overall tone was very pleasing. Big sound from a relatively small woofer. I wanted to crank it, but didn't because of the surrounds. The highs are very forward...not as crisp as I would like (compared to Mach2 bi-radial horn) but pretty darn good. The midrange seemed weak but this could be because of the bad surrounds ???

It was really difficult to tell if anything was coming out of the supertweeter...I think :scratch2: they were working, but jeez, can I even hear something at over 12,000 hz anymore ???? That's their crossover frequency BTW.

I think there is some real promise here. More to come after refoam job done. The impression I have is that these are built really well, with an overall high quality everywhere. There is a WOW factor here....my first impressions anyways...the right room size, placement, amp, sound source, and I think it's "lay back and enjoy the music". :thmbsp:

If the later versions are better, ...then I want some of those too.....oh heck, may as well spring for those 100's huh?

Give em an A so far

Ken C.

 

[Kencat]

Tech question woofer xover freq.

Ok, so far I'm talking to myself :screwy: ??

Technical question this time - what is the TRUE crossover frequency woofer to mid ??

Check out the two pics. First one is a cropped section from the brochure sent to me by luvvinvinyl. It says 1200 Hz. The second pic is from the instruction sheet stapled to the back of the speaker box. It says 2500 Hz.

Can't find the brochure pic - still looking.

This is from the Instruction Sheet on back of speaker.

Another inconsistency !

Anyone know why the differences here? or what the real crossover Freq is??

2500 Hz is pretty high for the woofer upper end. Instruction sheet probably wrong ?

Ken C.

 

[Grayhouse]

Nice little speaks there, Ken :thmbsp: I gotta question about those woofs. Is the foam glued from behind? They kinda look that way in the pic. Also you're gonna want to be carefull with those cones I think the early HPM woofer cones were impregnated with some kinda carbon wich can make them rather brittle if you're not carefull. I think it's what gives them that kinda green color. About the super tweeters. From what I have read they are the weekest link in the HPM series. You might want to pull the connections from the mids to make sure you are getting any sound from them. Regarding Frequency responce I would be more inclined to believe the lit on the back of speakers considering that the specs in brochures were always subject to change. But then again I could be wrong about all of the above :scratch2:

 

[bigphil]

I have my "new" early-version HPM-60s at home now after a 5 hr trip to get them.
....

Ken C.

did you get those off ebay? I eyed them for a long time, I hope you enjoy them... good luck with the restoration.

 

[MarkAnderson]

Ok, so far I'm talking to myself :screwy: ??

:lmao: If it makes you feel any better, I have been trying to reply to this for about an hour and a half.........life (read: the kids) has been gettin' in the way. Regarding the x/o frequency - I'd think 1200hz seems a lot more realistic for a 10" four-way design, but I'd also be more inclined to believe the documentation that came with the speakers vs. a sales brochure. I know - I'm not helping. BTW, I'll be refoaming a pair of HPM-40 woogers (maybe I should just let that die) shortly, so I'll be interested how it goes for you.
- Mark

 

[Kencat]

Nice little speaks there, Ken :thmbsp: I gotta question about those woofs. Is the foam glued from behind? They kinda look that way in the pic. Also you're gonna want to be carefull with those cones I think the early HPM woofer cones were impregnated with some kinda carbon wich can make them rather brittle if you're not carefull. I think it's what gives them that kinda green color. About the super tweeters. From what I have read they are the weekest link in the HPM series. You might want to pull the connections from the mids to make sure you are getting any sound from them. Regarding Frequency responce I would be more inclined to believe the lit on the back of speakers considering that the specs in brochures were always subject to change. But then again I could be wrong about all of the above :scratch2:

Yup, these foams are indeed glued from behind. The cones are also a very strange feeling material. When rubbing your finger over the material it is rough, almost feels like fiberglass, definitely pretty stiff material. The owner of the little electronics store where I picked up the foam surrounds said to just glue them to the fronts.....noooo, I don't think so !. These foams are very thin, as are the originals, about 1/32" thick.

The supertweets are pretty interesting eh? I'll have to figure out some way to test them. I was hoping I'ld be able to download a test program that sent out a very high freq that would confirm these were working before having to dismantle anything (if it ain't broke......). Will exhaust that avenue first :yes:

Re woofer crossover. 2500 hz seems high, but then I recall another post about a very similar discussion. Actually I think it was about the HPM-100. I'm going to have to search that further. Some guy tried a new crossover to lower the xover point but it was a disaster.

More investigation or a knowledgeable post required here.

Ken C.

 

[Kencat]

did you get those off ebay? I eyed them for a long time, I hope you enjoy them... good luck with the restoration.

Yes, got them off Ebay. Came down to the last seconds and I gave it a shot. There wasn't much interest in the bidding. I lucked out.

That's the GOOD part of ebay.....the odd real bargain once in a while eh? I'll think they'll be a keeper set for a while :yes:

Ken C.

 

[Kencat]

:lmao: If it makes you feel any better, I have been trying to reply to this for about an hour and a half.........life (read: the kids) has been gettin' in the way. Regarding the x/o frequency - I'd think 1200hz seems a lot more realistic for a 10" four-way design, but I'd also be more inclined to believe the documentation that came with the speakers vs. a sales brochure. I know - I'm not helping. BTW, I'll be refoaming a pair of HPM-40 woogers (maybe I should just let that die) shortly, so I'll be interested how it goes for you.
- Mark

I DO feel better now....I was <one-eyed-blink>beginning to <head-twitch> wonder though<uncontrolled-cheek-jerk> .....

Ken C.

 

[Kencat]

The link to other thread regarding the woofer upper end xover freq is http://audiokarma.org/forums/showthread.php?t=42436&highlight=hpm-100

The same issue was there, where the speaker attached instruction sheet said the xover was at 3000Hz...and that's a 12" woofer. Something is not right.

Ken C.

 

[silverchris]

You're foams are glued to the back? Mine are glued to the front but mine where redone by a shop a few years back aparently.

 

[Grayhouse]

Yup, these foams are indeed glued from behind. The cones are also a very strange feeling material. When rubbing your finger over the material it is rough, almost feels like fiberglass, definitely pretty stiff material. The owner of the little electronics store where I picked up the foam surrounds said to just glue them to the fronts.....noooo, I don't think so !. These foams are very thin, as are the originals, about 1/32" thick.

The supertweets are pretty interesting eh? I'll have to figure out some way to test them. I was hoping I'ld be able to download a test program that sent out a very high freq that would confirm these were working before having to dismantle anything (if it ain't broke......). Will exhaust that avenue first :yes:

Re woofer crossover. 2500 hz seems high, but then I recall another post about a very similar discussion. Actually I think it was about the HPM-100. I'm going to have to search that further. Some guy tried a new crossover to lower the xover point but it was a disaster.

More investigation or a knowledgeable post required here.

Ken C.

Yep. Thats the carbon in the woofers that makes them stiff and light at the same time. Gluing those little 10's from behind will give you some valuable experience for when you tackle those monsters on your Mach's :yes:

I'm pretty certain you should be able to hear something from those super tweets without the assistance of a high frequency test pattern. After all the're designed for human ears, not dog ears, so I'm certain you should be able to hear something if the're working Just disconect the mids and woof and see what happens. If you can't hear anything then there either shot, or I'm afraid your ears have seen better days then :sigh:

And as a side line....It's my 100th post

 

[Kencat]

Supertweeters must be working

I downloaded a 15,000 Hz sine wave test tone and played it into the Denon via the computer. Disconnected the LH speaker and hooked up each HPM-60 (separately) to the RH side and applied the 15,000 Hz test tone. I was able to hear the test tone in each speaker.

Good news on two counts:

(1) the supertweeters work in my new HPM-60s
(2) my ears are still somewhat ok

The only thing that might be fooling me, is if the tweeters were carrying the signal, even though the xover is spec'ld at 12,000 hz.
I covered the tweeter solidly with my hand while playing the test tone and still got a strong tone. The volume level I used was the same as I used on the Mach 2s when first trying the test tone.


FYI - the test tone and others are available here http://www.eminent-tech.com/music/multimediatest.html



For now, I am concluding that the supertweets work; however, feel fully authorized to burst my bubble with a response if this test is flawed.

Question: When I have the woofers out for refoam, can any harm be done by disconnecting the tweeters and run this test tone test without those drivers attached? (as Grayhouse has suggested already , just want to make sure nothing bad might happen doing that, like changing the overall impedance of the speaker ?)

I suppose this would be the absolute way to tell if the supertweets are tweeting.

Ken C.

 

[silverchris]

Hey Kencat could you check your woofers resistance for me?

 

[Grayhouse]

For now, I am concluding that the supertweets work; however, feel fully authorized to burst my bubble with a response if this test is flawed.

Question: When I have the woofers out for refoam, can any harm be done by disconnecting the tweeters and run this test tone test without those drivers attached? (as Grayhouse has suggested already , just want to make sure nothing bad might happen doing that, like changing the overall impedance of the speaker ?)

I suppose this would be the absolute way to tell if the supertweets are tweeting.

Ken C.

No bubble bursting here, Ken. It sounds like your supertweets are working fine. You will do no damage to your speakers if you wish to test them without the woofers. It'll sound like crap without any bottom end, but they will be just fine for a quick test. Remember also that the amount of volume coming from very high frequency drivers like your super tweeters is always gonna be much lower than the rest of the drivers since they only have to carry such a small range of frequency and this of course also relates to how effecient your ears are. For as one ages one tends to loose the ability to hear higher frequencies....No I'm not a doctor, but I do play one on TV

BTW: thanks for the link. It looks like that will come in handy someday :thmbsp:

 

[Strawman]

Cool project, and I like the link with the test tones. And very funny Mark, must be like a song in your head that you can't get rid of. :lmao:

 

[Kencat]

Replacing Foam Surround on Early Version HPM-60 Woofer Part 1.

Well, I finally started to dig in and begin replacing the foam surround on one of the woofers. This is my first attempt at ever doing this, but I've been reading a lot, and Grayhouse's tutorial helped quite a bit as well. :yes:

I have run into a slight problem though, the new surrounds I bought are too small....to work being glued to the underside of the cone that is. Pics and data to follow in later posts

There is a very interesting feature of these woofers that I have not seen in pictures or mentioned in text. There appears to be a paper gasket that was glued to the steel basket flange. The foam was glued on top of this paper gasket, and another paper gasket placed on top of the foam, with the rubber gasket placed on top of this paper gasket. see pics below.

I'm not sure if I need, or should copy this original design. Has anyone seen this before ??, and/ or know what the purpose or benefit would be ?? See pics in the next posts.

Story by Pictures

This is the woofer as it started out.

The next picture shows the original foam glued to the underside of the cone.

The next step was to remove the old foam. I did this gently by hand. The foam tore apart easily, it almost felt damp, not dry and crumbly as I've read.

To remove the rubber gasket, I used a carpet knife. It seemed to give a nice controllable feel with the large handle, and I took my time slowly working the tip in under the gasket.

The next pic shows using the carpet knife as a wedge under the gasket, after I got the gasket popped off partly around.

More to follow next post.

 

[Kencat]

Replacing Foam Surround on Early Version HPM-60 Woofer Part 2.

The following picture shows the Paper Gasket material that I described in Part 1. It covered the entire flange, whereas, the foam did not.

This picture shows the Paper Gasket over top and under the foam.

This next picure shows the paper gasket peeled back. It had a delaminating property.

This picture shows the flat bladed Exacto knife I found worked well to get the Paper Gasket off the steel flange and because I didn't have any Alcohol, I tried the nail polish remover. It worked....softened up the Paper Gasket and glue.

More to come.

Ken C.

 

[Kencat]

Replacing Foam Surround on Early Version HPM-60 Woofer Part 3.

Purchased Surround Won't Work :cry:

The 1st two pictures show the new surround fitted with the foam under the cone. It may be hard to tell, but the cone is riding pretty high on the foam 1/2 roll. The cone outer diameter is larger than the inside diameter of the foam.

This picture is a closeup of the cone/roll mismatch.

Cone Diameter measured at 7-13/16 "

New foam inside dia measured at 7-9/16". 1/4" too small on the diameter !!! (looks like 7-1/2" in the pic, but closer to the 7-9/16" by eye - paralax error)

I will be looking for a surround that will fit the cones diameter. This is going to stall things for a while . Need to get the other woofer prepped and ready to go in the meantime.

Ken C.

 

[Kencat]

Replacing Foam Surround on Early Version HPM-60 Woofer Part 4.

This one picture shows the new surround placed on top of the cone. This is SO tempting to just glue it on this way. Not shown but the Rubber gasket fits around the the foam perfectly.....nice 1/16" gap to the outer diameter of the 1/2 roll.

Ken C.