I just came across a pair of HPM-100's at an estate sale for $50. While
I knew they were going to be a part of the estate sale, I didn't get a
chance to check their conditiion prior to sale.... So for fear of
losing them to the "next guy", I snapped them up!. I got them home,
hooked them up and it appears every driver is blown except the
woofers... Yes I can live with that because I was probably going to
replace all drivers anyway since every dust cap is pushed in, plus the
drivers seem reasonable on ebay. The cabinets look great which gives me
the green light to go ahead with the project. My question is, how can I
be certain the crossovers are fine? I thought since all drivers were
blown except woofers, that maybe the crossovers were trashed as well,
but it seems the pots were just dirty and they are now outputting
sound. But how can I be sure the crossovers are 100% before I start the
process of acquiring replacement drivers? I remember when these guys
were new "back in the day" but I was just a kid with no money. I wish
they were in better condition but I love projects.......especially
audio projects!

In article .com, wrote:
I just came across a pair of HPM-100's at an estate sale for $50. While
I knew they were going to be a part of the estate sale, I didn't get a
chance to check their conditiion prior to sale.... So for fear of
losing them to the "next guy", I snapped them up!. I got them home,
hooked them up and it appears every driver is blown except the
woofers... Yes I can live with that because I was probably going to
replace all drivers anyway since every dust cap is pushed in, plus the
drivers seem reasonable on ebay. The cabinets look great which gives me
the green light to go ahead with the project. My question is, how can I
be certain the crossovers are fine? I thought since all drivers were
blown except woofers, that maybe the crossovers were trashed as well,
but it seems the pots were just dirty and they are now outputting
sound. But how can I be sure the crossovers are 100% before I start the
process of acquiring replacement drivers? I remember when these guys
were new "back in the day" but I was just a kid with no money. I wish
they were in better condition but I love projects.......especially
audio projects!

You can test caps to see if they have shorts.They may be hard to read.
A capacitor meter as well as an ESR meter will give indications, but
if your rebuilding, I would just order new, same value caps. Coils should be OK,
allthough they can develop shorted turns creating problems. Another method
is to hook up something to the outputs, use low level signals, and compare
pink noise between the two speakers. Check all crimps when rebuilding, as
I would also recommend soldering all connections. Pots can be troublesome.
I personally like to switch to fixed resistors once proper levels are found.

greg

GregS spake thus:

In article .com, wrote:

I just came across a pair of HPM-100's at an estate sale for $50. While
I knew they were going to be a part of the estate sale, I didn't get a
chance to check their conditiion prior to sale.... So for fear of
losing them to the "next guy", I snapped them up!. I got them home,
hooked them up and it appears every driver is blown except the
woofers...

I would also recommend soldering all connections. Pots can be troublesome.
I personally like to switch to fixed resistors once proper levels are found.

Or just do as I did and get rid of 'em altogether. My pair of AR-2s that
I got dirt cheap had ruined rheostats (not pots, just 2 connections), so
I just hard-wired them at the "full-on" setting. (That's what tone
controls on the amp are for!)


--
Any system of knowledge that is capable of listing films in order
of use of the word "****" is incapable of writing a good summary
and analysis of the Philippine-American War. And vice-versa.
This is an inviolable rule.

- Matthew White, referring to Wikipedia on his WikiWatch site
(http://users.erols.com/mwhite28/wikiwoo.htm)

wrote in message
oups.com...
I just came across a pair of HPM-100's at an estate sale for $50. While
I knew they were going to be a part of the estate sale, I didn't get a
chance to check their conditiion prior to sale.... So for fear of
losing them to the "next guy", I snapped them up!. I got them home,
hooked them up and it appears every driver is blown except the
woofers... Yes I can live with that because I was probably going to
replace all drivers anyway since every dust cap is pushed in, plus the
drivers seem reasonable on ebay. The cabinets look great which gives me
the green light to go ahead with the project. My question is, how can I
be certain the crossovers are fine? I thought since all drivers were
blown except woofers, that maybe the crossovers were trashed as well,
but it seems the pots were just dirty and they are now outputting
sound. But how can I be sure the crossovers are 100% before I start the
process of acquiring replacement drivers? I remember when these guys
were new "back in the day" but I was just a kid with no money. I wish
they were in better condition but I love projects.......especially
audio projects!

**It doesn't matter if the crossovers are OK, or not. Unless the replacement
drivers are absolutely IDENTICAL, the crossovers will be pretty much useless
anyway.


--
Trevor Wilson
www.rageaudio.com.au



--
Posted via a free Usenet account from http://www.teranews.com

I am having a heck of a time cleaning the pots, there doesn't seem to
be any openings to shoot contact cleaner in... And it seems very
difficult to remove the pots assembly from the front baffle. Is there a
way of cleaning these without removing the assembly? (They are mounted
on a plastic plate stapled to the front baffle!) An alternative would
be to bypass them....(I never use these anyway and keep a flat
setting...) Is the output from the crossover to the pots a flat setting
anyway, so i could bypass? I wanted to do a 100% restoration on these
and would like them to be functional, but...

Thanks guys!

spake thus:

I am having a heck of a time cleaning the pots, there doesn't seem to
be any openings to shoot contact cleaner in... And it seems very
difficult to remove the pots assembly from the front baffle. Is there a
way of cleaning these without removing the assembly? (They are mounted
on a plastic plate stapled to the front baffle!) An alternative would
be to bypass them....(I never use these anyway and keep a flat
setting...) Is the output from the crossover to the pots a flat setting
anyway, so i could bypass? I wanted to do a 100% restoration on these
and would like them to be functional, but...

Just bypass the pots: wire them in their full "on" position (fully
clockwise, I assume). Then you won't have to worry about them.


--
Any system of knowledge that is capable of listing films in order
of use of the word "****" is incapable of writing a good summary
and analysis of the Philippine-American War. And vice-versa.
This is an inviolable rule.

- Matthew White, referring to Wikipedia on his WikiWatch site
(http://users.erols.com/mwhite28/wikiwoo.htm)

Okay, I have bypassed the pots! (I love heat shrink tubing!) I was
actually able to remove the back cover of the pots while they were
still installed in the cabinet, but contact cleaner still wouldn't
bring them back to life! My next question... A previous poster
mentioned that by bypassing the pots, that this is the same as both
pots at their highest setting. What value resistor could I put inline
that would bring them (mid and high) to a flat value? Thanks!

spake thus:

Okay, I have bypassed the pots! (I love heat shrink tubing!) I was
actually able to remove the back cover of the pots while they were
still installed in the cabinet, but contact cleaner still wouldn't
bring them back to life! My next question... A previous poster
mentioned that by bypassing the pots, that this is the same as both
pots at their highest setting. What value resistor could I put inline
that would bring them (mid and high) to a flat value? Thanks!

How about R/2, where R=resistance of pot? (At least a good starting
point; use you ears.)


--
Any system of knowledge that is capable of listing films in order
of use of the word "****" is incapable of writing a good summary
and analysis of the Philippine-American War. And vice-versa.
This is an inviolable rule.

- Matthew White, referring to Wikipedia on his WikiWatch site
(http://users.erols.com/mwhite28/wikiwoo.htm)

How can I determine the ohm value of the pot? I then take that value
and divide by two for a value of the resistor?

spake thus:

How can I determine the ohm value of the pot? I then take that value
and divide by two for a value of the resistor?

Ever heard of an ohmmeter? One of the functions of a multimeter.
Available everywhere, cheap.


--
Any system of knowledge that is capable of listing films in order
of use of the word "****" is incapable of writing a good summary
and analysis of the Philippine-American War. And vice-versa.
This is an inviolable rule.

- Matthew White, referring to Wikipedia on his WikiWatch site
(http://users.erols.com/mwhite28/wikiwoo.htm)

I've been reading that I cannot simply put a resistor in line to each
driver since the pots on the HPM-100 are L-Pads... It requires a
resistor in parallel and in series... I'm wondering if just simply
wiring in another L-Pad inside the cabinet would be easier altogether.
Then I could measure the flat response of the original with an ohmeter
and simply adjust the new L-Pad to match. Something like this one:
http://www.partsexpress.com/pe/showd...Number=260-262

What do you guys think?

wrote:
I've been reading that I cannot simply put a resistor in line to each
driver since the pots on the HPM-100 are L-Pads... It requires a
resistor in parallel and in series... I'm wondering if just simply
wiring in another L-Pad inside the cabinet would be easier altogether.
Then I could measure the flat response of the original with an ohmeter
and simply adjust the new L-Pad to match. Something like this one:
http://www.partsexpress.com/pe/showd...Number=260-262

What do you guys think?

If it's wired the way an L-pad would usually be wired (I think...) then only
2 connections are used, and the resistance would vary from near zero to the
full value of the L-pad (maybe up to about 50 ohms). If I am correct about
this - and others around here will be quick to let me know, I'm sure - then
you could just bypass the L-pad altogether or replace it with a medium value
of resistance you select according to taste. If you do replace it with a
resistor, be sure to use one rated at least about 5 watts.

Mark Z.

Hi Mark! All 3 connections are used on the original Lpad...which leads
me to believe I can't just use one resistor per driver.

wrote:
Hi Mark! All 3 connections are used on the original Lpad...which leads
me to believe I can't just use one resistor per driver.

Well, then I suppose you would just measure across the whole pot, decide the
resistance value on either side of the center tap, and use two resistors as
a series pair, with signal in, "ground" and center connection out to the
tweeter. Some experimentation may be required, and try to be as accurate as
possible with the total resistance of the pair - in combination with the low
impedance of the tweeter itself (or midrange for that matter) the value of
the resistors becomes a pretty large part of the equation.


Mark Z.