Where can I find replacement JBL Speaker crossover caps, Vintage
DMHenrie
'75-'76. They are in perfect condition, with the oak aging very nicely (they
were more blonde originally, now have a medium patina). ANyway, I have had
the woofers reconed so now I want to replace the corssover capacitors.
Where is a good source to find the caps? Any ideas?
Audio Empire
(in article <7vetoi...@mid.individual.net>):
Do yourself a favor and replace your crossover caps with the same value(s) as
are in the crossover NOW with polypropylene equivalents such as those shown
here:
as well as other sources. Some brands that are good are Wonder Caps and
Sidereal Caps, but there are others.
http://www.laventure.net/parts4sale/capacitors.htm
A little anecdote might illustrate their worth. A number of years ago, I was
the owner of a "pair" of Magnepan Tympani III C speakers. I put the word
'pair' in quotes because These speakers consisted of EIGHT HUGE panels (two
tweeter panels, two midrange panels and FOUR bass panels) which took-up the
entire end of the room! Anyway, Magnepan shipped these speakers with the
standard (at the time) oval shaped mylar capacitors in the crossover between
the tweeter and the midrange (the woofers had their own amps and a low-level
active crossover between the preamp and the amps).
I ordered some Wonder Caps of the correct values to replace the stock mylars
in the passive crossovers inside the speaker covers. The Saturday afternoon
when I decided to change the caps, a buddy of mine was over at my place (as
was his wont when he had nothing else to do). Now this guy was not an audio
guy, but he did like music, and appreciated good sound.
I got down on the floor behind the Maggies with soldering iron and tools and
soon swapped out the polypropylene Wonder Caps for the stock mylars while my
buddy read a magazine. He wasn't really paying any attention to what I was
doing. When I was finished, I fired up the stereo and played some music. As
walked back into the room (the stereo system was in an unused, adjacent
bedroom) my buddy had put the magazine down and was staring in rapt attention
at the speakers. "What did you just do?" He asked. I told him that I had just
swapped capacitors in the crossover between the tweeters and midrange panels.
Well, by this time I was in the room with the speakers and I too had noted
that the speakers sounded as if several layers of blankets had been removed
from them. They sounded so much cleaner and more transparent, that even my
friend who hadn't been paying the slightest attention to what i was doing,
noticed the improvement instantly. So did I.
Putting good quality polypropylene caps in your crossover will revolutionize
the sound of your speakers. It's NOT subtle. I can almost guarantee it. It is
important, however to match the values in order not to move the rollover
points.
Many here will likely tell you that Walt Jung's research into dielectric
absorption distortion in the 1980's has been largely discredited and perhaps
he did misattribute the phenomenon, but the results certainly are real. I had
a Hafler DH-101 preamp once that I built as a kit. Another friend bought the
same kit at the same time and we both built them. He built his stock, and I
replaced all the capacitors in the signal path with polypropylene units as I
built mine. We arranged an ad-hoc double blind test of the two preamps at my
digs. Our other buddies weren't told what the differences were between the
two units. The preamps were connected to my power amps via a simple
Switchcraft surface-mount 3 -in, 1-out stereo source switch. Remember, that
my stereo was in a different room from the speakers. We all took turns
switching between the two preamps and the outputs were matched exactly for
level using an audio voltmeter. A Phillips CD player was "Y'd" between the
two preamps. Everyone could hear the difference EVERY TIME the Hafler with
the polypropylene caps was switched in. All kinds of music was played, and
nobody ever got the two preamps mixed up the modified Hafler was cleaner,
more transparent, and less fatiguing. So don't tell me that caps don't make a
difference.
ScottW
> On Sat, 6 Mar 2010 03:48:34 -0800, DMHenrie wrote
>
> > I have a pair of JBL Decade L-36 3-ways, that I have since new way back=
in
> > '75-'76. They are in perfect condition, with the oak aging very nicely =
(they
> > were more blonde originally, now have a medium patina). ANyway, I have =
had
> > the woofers reconed so now I want to replace the corssover capacitors.
> > Where is a good source to find the caps? Any ideas?
>
) as
> are in the crossover NOW with polypropylene equivalents such as those sho=
wn
> here:
>
> http://tinyurl.com/ybhqycp
>
I had a similar project in replacing the input caps on Quad 63s.
Initially I replaced the electrolytics with a poly caps (which are
much larger
and had to go external) but used the same wire wound resistor types as
the originals (which had overheated and cracked ceramic).
Differences were subtle IMO.
After I found the replacement resistors also overheated and cracked I
replace them with low inductance metal oxide resistors in T0-220
package with a proper heat sink. I found that difference to be more
significant though it's very hard to say what the impact of the
damaged resistors was. They ohmed out at the correct value but I
didn't bother trying to see what they were doing when under stress.
ScottW
ze...@comcast.net
> On Sat, 6 Mar 2010 03:48:34 -0800, DMHenrie wrote
>
> > I have a pair of JBL Decade L-36 3-ways, that I have since new way back=
in
> > '75-'76. They are in perfect condition, with the oak aging very nicely =
(they
> > were more blonde originally, now have a medium patina). ANyway, I have =
had
> > the woofers reconed so now I want to replace the corssover capacitors.
> > Where is a good source to find the caps? Any ideas?
>
) as
> are in the crossover NOW with polypropylene equivalents such as those sho=
wn
> here:
>
> http://tinyurl.com/ybhqycp
>
> as well as other sources. Some brands that are good are Wonder Caps =A0an=
d> A little anecdote might illustrate their worth. A number of years ago, I =
was
> the owner of a "pair" of Magnepan Tympani III C speakers. I put the word
wo
> tweeter panels, two midrange panels and FOUR bass panels) which took-up t=
he
> entire end of the room! Anyway, Magnepan shipped these speakers with the
een
> the tweeter and the midrange (the woofers had their own amps and a low-le=
vel
> active crossover between the preamp and the amps).
>
ars
> in the passive crossovers inside the speaker covers. The Saturday afterno=
on
> when I decided to change the caps, a buddy of mine was over at my place (=
as
> was his wont when he had nothing else to do). Now this guy was not an aud=
io
> guy, but he did like music, and appreciated good sound.
>
and
> soon swapped out the polypropylene Wonder Caps for the stock mylars while=
my
> buddy read a magazine. He wasn't really paying any attention to what I wa=
s
> doing. =A0When I was finished, I fired up the stereo and played some musi=
c. As
> walked back into the room (the stereo system was in an unused, adjacent
tion
> at the speakers. "What did you just do?" He asked. I told him that I had =
just
> swapped capacitors in the crossover between the tweeters and midrange pan=
els.
> Well, by this time I was in the room with the speakers and I too had note=
d
> that the speakers sounded as if several layers of blankets had been remov=
ed
> from them. They sounded so much cleaner and more transparent, that even m=
y
> friend who hadn't been paying the slightest attention to what i was doing=
,
> noticed the improvement instantly. So did I.
>
ize
> the sound of your speakers. It's NOT subtle. I can almost guarantee it. I=
t is
> important, however to match the values in order not to move the rollover
> points.
>
> Many here will likely tell you that Walt Jung's research into dielectric
aps
> he did misattribute the phenomenon, but the results certainly are real. I=
had
> a Hafler DH-101 preamp once that I built as a kit. Another friend bought =
the
> same kit at the same time and we both built them. He built his stock, and=
I
> replaced all the capacitors in the signal path with polypropylene units a=
s I
> built mine. We arranged an ad-hoc double blind test of the two preamps at=
my
> digs. Our other buddies weren't told what the differences were between th=
e
> two units. The preamps were connected to my power amps via a simple
at
> my stereo was in a different room from the speakers. We all took turns
r
> level using an audio voltmeter. A Phillips CD player was "Y'd" between th=
e
> two preamps. Everyone could hear the difference EVERY TIME the Hafler wit=
h
> the polypropylene caps was switched in. All kinds of music was played, an=
d
> nobody ever got the two preamps mixed up the modified Hafler was cleaner,
ke a
> difference. =A0
On speakers, changing the capacitor types can change the original
intended sound
due to changes in ESR, etc. Of course better tolerance is a good
thing. Longevity
is another good thing. If the sound suits you then you have done a
good thing.
greg
Arny Krueger
news:hmtvj...@news4.newsguy.com...
> Putting good quality polypropylene caps in your crossover will
> revolutionize
> the sound of your speakers. It's NOT subtle. I can almost guarantee it. It
> is
> important, however to match the values in order not to move the rollover
> points.
The most likely changes that putting film caps into a speaker crossover is
that the actual capacitance values and ESR of the capacitors will change.
If your speaker crossover has electrolytic caps in it, then they were
probably specified to a tolerange of +/- 20% with +80, -20 being a
possibility. The film caps will perform within just a few percent of their
specified values. Good film caps will also reduce ESR which may or may not
be good thing, but can make an audible difference. Note that if you reduce
the ESR of parts in a speaker crossover, there may be adverse changes in
frequency response.
The biggest problem with evaluations like this is that the actual
performance of the equipment is rarely if ever checked out fully. I'm not
just talking about a few spot frequency response checks (it's not clear what
frequencies were checked above). I would like to see a test suite like the
RMAA suite be performed. This can be done with minimal trouble and cost if
you know what you are doing. In the case of kits, its not clear that subtle
assembly problems weren't part of the evaluation.
The classical "I did a listening test and heard a difference" anecdote
typically includes zero safeguards to ensure that the equipment was
operating properly before and after the alleged upgrade.
If capacitors make an audible difference then there will be measureable
changes, usually in relatively obvious areas like frequency response. Change
the capacitance and ESR of capacitors, and any differences that are
obvserved are hardly mysteries.
Audio Empire
(in article <7vkqob...@mid.individual.net>):
No, they're not mysteries at all and since I used the SAME values as the caps
that came with the unit, and since polypropylenes have far less ESR than the
stock caps, the performance of the preamp is bound to be at least measurably
better. Frequency sweeps over the audio passband showed that both preamps had
identical frequency responses (within the accuracy of the HP audio voltmeter
used, of course. It read less than +/- 0.5 dB. How accurate that is I have no
way to tell). The differences heard in the DBT were probably distortion, The
Hafler was an inexpensive preamp and had cheap coupling and bypass caps in
the audio section. These are what I replaced (with polypropylenes). I also
bypassed the power supply filter caps with polypropylenes. All of this was
done with the same values as the stock caps. The filter bypass caps were
chosen according to an article on the subject (by Walt Jung) in the "Audio
Amateur".
Anyway the amps were tested on the bench for frequency response, and DBT'd
for sound. The overwhelming preference was for the Hafler with the
polypropylenes caps. Good enough result for me to decide that caps do make a
marked difference. well designed modern equipment comes with these types of
caps and such swaps aren't necessary any more. But this guy's JBLs will
certainly benefit from upgrading the capacitors. I can pretty much guarantee
that. I mean, if he's going to replace the caps anyway, why not use better
quality ones (of the same value as the old ones, of course, but with
obviously lower ESR.)
Audio Empire
(in article <7vkgsb...@mid.individual.net>):
[ Extensive quotation snipped. Please trim more carefully in
future. -- dsr ]
> On speakers, changing the capacitor types can change the original
> intended sound
> due to changes in ESR, etc.
In all the speakers that I have swapped out mylars for polypropylenes, the
main difference has been one of perceived clarity in the upper mids and
highs. This "change in sound" is definitely for the better. I have never
noticed that such a swap resulted in any change in crossover points, but if
it does, it's minimal and not really noticeable. The increased clarity seems
to be well worth the difference (if any).
Of course better tolerance is a good
> thing. Longevity
> is another good thing. If the sound suits you then you have done a
> good thing.
> greg
Obviously.
Arny Krueger
> On Mon, 8 Mar 2010 09:34:04 -0800, Arny Krueger wrote
> No, they're not mysteries at all and since I used the SAME values as the
> caps
> that came with the unit, and since polypropylenes have far less ESR than
> the
> stock caps, the performance of the preamp is bound to be at least
> measurably
> better.
Not necessarily. My comments about ESR related primarily to passive
crossovers in loudspeakers.
> Frequency sweeps over the audio passband showed that both preamps had
> identical frequency responses (within the accuracy of the HP audio
> voltmeter
> used, of course. It read less than +/- 0.5 dB. How accurate that is I have
> no
> way to tell).
I can generally perfectly ABX - identify two pieces of gear that differ by
just under +/- 0.5 dB over the audio range based only on the level and FR
differences.
The "ABX standard" is +/- 0.1 dB, 20-20 KHz.
> The differences heard in the DBT were probably distortion,
Unlikely. The only capacitors that have measurably greater distoriton are
high-value ceramics and unbiased electrolytics, and then only if misused. I
don't have a schematic for a DH 101, but I do have the schematic for a
DH100. The DH 100 is actually a very high quality design with *no*
electrolytic or ceramic capacitors in the signal path. The op amps are low
noise, low distortion, high slew parts that I've also seen used in
professional gear.
>The Hafler was an inexpensive preamp and had cheap coupling and bypass
>caps in
> the audio section.
The DH100 parts list shows extensive use of polypropylene capacitors, as
suggested by Jung/Marsh.
> These are what I replaced (with polypropylenes). I also
> bypassed the power supply filter caps with polypropylenes. All of this was
> done with the same values as the stock caps. The filter bypass caps were
> chosen according to an article on the subject (by Walt Jung) in the "Audio
> Amateur".
Unless they appreciably cheapened the DH101 after the DH 100, you replaced a
lot of polypropylene capacitors with polyproplylene capacitors. :-(
Audio Empire
(in article <7vl5r0...@mid.individual.net>):
the DH-101 had no op-amps and is all discrete bipolar transistors
(10/channel, in fact). It did have coupling caps (4/channel) in the signal
path.
http://www.hafler.com/techsupport/pdf/DH-101_preamp_man.pdf
PPS 12 and 13.
>
>> The Hafler was an inexpensive preamp and had cheap coupling and bypass
>> caps in
>> the audio section.
>
> The DH100 parts list shows extensive use of polypropylene capacitors, as
> suggested by Jung/Marsh.
That's not the DH-101 The DH-100 was a ten-year newer model (1988). The
DH-101 came out in 1978 and was sold as a kit. It had cheap push-to-cancel
switches (that got noisy and intermittant) and cheap pots which also became
noisy. It sounded pretty good when new, but went downhill quickly due to the
low quality of the moving parts. I believe the kit was less than $200. I only
kept it for about two years before moving on.
>> These are what I replaced (with polypropylenes). I also
>> bypassed the power supply filter caps with polypropylenes. All of this was
>> done with the same values as the stock caps. The filter bypass caps were
>> chosen according to an article on the subject (by Walt Jung) in the "Audio
>> Amateur".
>
> Unless they appreciably cheapened the DH101 after the DH 100, you replaced a
> lot of polypropylene capacitors with polyproplylene capacitors. :-(
The DH-101 was first (don't ask me why it has a higher number) and definitely
did NOT have polypropylene caps in it and in fact, some of the coupling caps
were actually tantalums (there's a disgusting thought for you). See the parts
list on Page 13. The Wonder Caps I used in that unit were so big, that they
hardly fit in the case (you can imagine the size of a 10 uFd non-polarized
polypropylene capacitor (IIRC, that was as big as they came!). Luckily, there
is a big empty area in the case behind the main circuit board where, with an
ample supply of hot glue and tie-wraps, one could stuff the caps. Caps that
were bigger than 10 uFd (and weren't coupling caps) were left in place and
bypassed by 1 uFd polypropylenes.
I never had a DH-100 but I did have a DH-110, also a kit, also discrete
bi-polar transistor. Dunno how I missed the DH-100. Frankly, until you
mentioned it, I don't recall ever having heard of it! I see by the schematic
that it looks pretty good. I'll bet it performed well too.
>
>
>
Dick Pierce
>
> In all the speakers that I have swapped out mylars for polypropylenes, the
> main difference has been one of perceived clarity in the upper mids and
> highs. This "change in sound" is definitely for the better. I have never
> noticed that such a swap resulted in any change in crossover points, but if
> it does, it's minimal and not really noticeable. The increased clarity seems
> to be well worth the difference (if any).
>
Let me illustrate a specific and demonstrable case where swapping
and ostensibly "better" part is garaunteed to result in worse
performance.
One of my clients had me design a network for their speaker
that used the Vifa 1" ring-dome radiator tweeter. It does not
use ferrofluid in the gap, with the net result that its
impedance peak at resonance is fairly sizable, on the order of
25 ohms or so at about 650 Hz. This was enough that it would
screw up any plausible 2nd- or 3rd- order network and without
impedance compensation, it is impossible to achieve the design
target for the crossover response.
So, an onjugate network, consisting of a series LRC was designed
to go in parallel with the tweeter. The L and the C value depend
upon the effective mass and compliance of the driver, and the
R should be about equal to the DC resistance of the voice coil,
about 3.4 ohms. Since the L and R are in series, our good friend
Thevenin states that it makes no difference whether it's L followed
by R, R followed by L, 10 1/10Rs interspersed with 10 1/10Ls or,
in fact, an L whose DC resistance is 3.4 ohms. It just so happens
that I found an of the shelf air-core inductor wound of the right
value whose DC resistance was within about 3% of the value I needed,
meaning I could use 1 part instead of 2 AND because it was wound
with small wire, it was substantially less expensive to implement
it using a single high-resistance coil instead of a low-resistance
coil and a high-resistance resistor.
However, a number of people, when they opened up the speaker, saw
all these wonderful poly caps and this shitty little inductor. The
first step was to rip out the inductor and replace it with a hefty
low-resistance inductor.
Doing so completely screwed up the crossover, because it was
suposed to be a 3.4 ohm resistor in series with a 4 mH inductor,
NOT a 0.15 ohm resistor in seriers with a 4 mH inductor.
In a similar vein, a popular "tweak" of the old KEF RS104-AB
network was to rip out all the electrolytic caps and replace
them with polypropylenes and, yes, it DID change the sound,
but NOT necessarily for the better, because the ENTIRE crossover
was designed with knowledge of how EACH part in it worked.
Simply substituting parts is NOT necessarily a good way to go, no
matter what someone might like about the result. Without the
detailed knowledge about WHY a designer did it that way, how
could one possibly know WHY a part should or should not be
substituted at random.
--
+--------------------------------+
+ Dick Pierce |
+ Professional Audio Development |
+--------------------------------+
Audio Empire
(in article <hn6u...@news2.newsguy.com>):
I don't really understand why you are confusing the issue with, what I
consider, extreme examples of a hypothetical problem. Most speakers have used
Mylar caps in their crossovers (where feasible) for decades. While it is true
that polypropylene caps have somewhat lower ESR than do Mylars, it's nowhere
near a big enough delta to make any real difference in this application. Now,
I could see it if we were swapping polypropylenes for electrolytics or
tantalums. but not for Mylars.
Now if you know differently, I'd love to see some data that shows where the
crossover characteristics of a speaker system have been changed significantly
by swapping polypropylene caps for the same value of Mylar caps, as to make a
fundamental and profound enough change to audibly impact the speaker's
performance.
Dick Pierce
> On Tue, 9 Mar 2010 17:55:50 -0800, Dick Pierce wrote
> (in article <hn6u...@news2.newsguy.com>):
A "hypothetical" example? Sir, I gave two examples that were used
in production runs of at least three models from two manufacturers
whose total product runs were in the tens of thousands of units.
Hardly "hypothetical".
> Most speakers have used Mylar caps in their crossovers (where
> feasible) for decades. While it is true that polypropylene
> caps have somewhat lower ESR than do Mylars, it's nowhere
> near a big enough delta to make any real difference in this
> application.
I left my entire post intact. Where in my post did I ever
say anything about mylar caps? (hint: nowhere).
> Now, I could see it if we were swapping polypropylenes for electrolytics or
> tantalums. but not for Mylars.
Now, read my post again, especially the part that says:
"a popular 'tweak' of the old KEF RS104-AB network was
to rip out all the electrolytic caps and replace them
with polypropylenes and, yes, it DID change the sound,
but NOT necessarily for the better, because the ENTIRE
crossover was designed with knowledge of how EACH part
in it worked."
see if you can show us where I did not at all mention a
difference between electrolytics and various film capacitors.
(hint: it's there)
> Now if you know differently, I'd love to see some data that
> shows where the crossover characteristics of a speaker system
> have been changed significantly by swapping polypropylene caps
> for the same value of Mylar caps, as to make a fundamental and
> profound enough change to audibly impact the speaker's
> performance.
Since I never once made that assertion, I don't understand
why it's up to me to supply data to support or refute it.
The point of my post was to privide at least two example of
why substitution WITHOUT the detailed knowledge behind why
a particular component was used DOES NOT necessarily lead
to "better." Different, yes, but different is not necessarily
better.
Arny Krueger
> I don't really understand why you are confusing the issue
> with, what I consider, extreme examples of a hypothetical
> problem.
Like like a wind-up to a dismissal of an opinon from an expert witness.
> Most speakers have used Mylar caps in their
> crossovers (where feasible) for decades.
Right, where feasible, which means that there are tons of speakers still
being made with electrolytics in their crossovers.