| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 104.1 | | LARVAE::JEFFERY | K-I-L-L-E-D, Revoked | Thu Jul 20 1989 12:56 | 11 |
|
Well, you could try another set of speakers, and see if the problem
still exists. If both sound out-of-phase, then it is unlikely to
be the speakers and much more likely to be the amp. Incidentally,
the Diamonds are pretty easy to open up (I had to replace a woofer
in my Dad's pair).
Mark.
By Cambridge Alpha amp, do you mean "Arcam Alpha" ?? or Cambridge
P40 ?
|
| 104.2 | Above/below.neq.side-by-side | BAHTAT::SALLITT | Dave - @RKG & ICI, 0642432193 | Thu Jul 20 1989 13:12 | 17 |
| re .0.....
Why are you checking phasing by placing one speaker above the other?
They should be placed side by side; placing one above the other
will cause a change in sound because the dispersion above the speaker
is not the same as below it, unlike L & R dispersions which should
be identical.
Changing the speakers to out-of-phase may well fix what you perceive
with them placed vertically. What problem do you hear, apart from this,
that makes you think you have a phasing problem? What is wrong with
the system when speakers are connected normally?
I would not advise futzing with internal wires until you check the
phasing *properly*.
Dave
|
| 104.3 | You can test phasing easily | LATINA::RUPEREZ | Fails, but by another reason... | Fri Jul 21 1989 13:57 | 19 |
| Hi,
Dave is right. In order to know if speakers are phased, you should
put them in front each other separate between 2 and 3 inches, and
sending a mono bass signal (an deep organ music in stereo will do
the job too), you must move the balance knob until the sound you
are hearing to decreases (out-phase), or increases (in-phase).
They should be kept in-phase, but for measuring is better to check
the out-phase position first, because with a good bass signal, the
sound almost disappears (a test record would be ideal).
You'll realize the balance knob is not in the supposed "center"
position when that happens, this is normal, as no one amp has a real
testing done when come out from factory (the big class might be...)
You must turn your amp off when changing conections !!!.
After knowing the "center" point you can, if you dare or know who
can do it, open the amp and move that "center" point to the actual
center shown on fascia.
Setting up is an enjoying work too...
Good luck
Jose
|
| 104.4 | | GRAMPS::WCLARK | Walt Clark | Thu Jul 27 1989 13:20 | 33 |
| It is not uncommon to find leads reversed inside speaker cabinets
from the crossover to the drivers, or in many cases, only one
driver.
One can check the polarity of the LF driver connections externally
by connecting a small 1.5V drycell across the speaker terminals
(disconnect the speaker from the power amp first). Hook the +
battery lead to the + speaker terminal, - to -. The usual response
from the LF driver is it moves out toward the listener, although this
is not always the case. Either way, the pair of speakers should
move the same direction.
It is not common to find amplifier wiring errors at the speaker
leads. Most amps are not balanced drivers. The + lead is normally
fed from a single ended amplifier and the - lead is normally analog
ground, and sometimes tied to the - lead of the other channel. Speaker
driver terminals on the other hand are usually identical save for
some indistinct marking near the + lead which makes it easier to
get them backwards.
Checking the phasing of speakers using music and listening for base
is fine too, but you wont have any idea where the problem is if not
right (you migh have an invert switch thrown in the preamp for
instance). Also, because the wave length of base frequencies is
so large relative to speaker and room size, location of the 2 speakers
is not real important to check relative phase between the 2. You
should be aware though that moving the speakers, or one of them,
will alter the standing wave pattern in a room so it is possible that
the combined LF output of the speakers may sound lower from a fixed
location in the room when the speakers are closer together than when
in their original position.
Walt
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| 104.5 | | BURYST::EDMUNDS | $ no !fm2r, no comment | Fri Aug 04 1989 04:03 | 9 |
| The easiest way to check speaker phasing right through the system is to
placce both speakers face to face a few inches apart, and stick your
head batween them as you play a MONO source (or use mono sw on
amplifier) through them. If the sound comes from one central place,
they are in phase; if it comes from each speaker individually, they are
out of phase. Any doubt can be removed by reversing the phase of one
speaker and observing the difference.
Keith
|