Goofy Rowe R-80 Amp

hi, all-
still fighting the battle of the muddy bass. had the amp gone over,
soldering checked, connections cleaned. today when we installed the
cleaned up, the right channel sounds great when it's plugged in, the
left channel sounds great when IT'S plugged in, but together, the
muddy bass is back. we hooked an external turntable into the amp and
noticed that there is now an increasing in the volume output, and
increasing reverb. this is over the course of maybe ninety seconds. it
crossed my mind that maybe, just maybe, this may have something to do
with he feature of the "fade in" sound once the tone arm rests on the
turntable once a selection is made. any thoughts?
thanks-
john hayes

You have the speakers out of phase . remove the wires from ONE speaker
and reverse them

On 8 Aug 2004 14:52:13 -0700, (John Hayes) wrote:

hi, all-
still fighting the battle of the muddy bass. had the amp gone over,
soldering checked, connections cleaned. today when we installed the
cleaned up, the right channel sounds great when it's plugged in, the
left channel sounds great when IT'S plugged in, but together, the
muddy bass is back. we hooked an external turntable into the amp and
noticed that there is now an increasing in the volume output, and
increasing reverb. this is over the course of maybe ninety seconds. it
crossed my mind that maybe, just maybe, this may have something to do
with he feature of the "fade in" sound once the tone arm rests on the
turntable once a selection is made. any thoughts?
thanks-
john hayes



I had the same recently on an R-81. Bass was horrible and distorted.
Turned out that the edge surround of both bass speakers was totally
stuffed (in fact there wasnt any left). Replacing both the woofers
made the thing sound fantastic once more.

This is the unit before speaker replacement.
http://www.geocities.com/kenreed1999/R81Speaker.jpg

The reason that the problem isn't happening with one channel only is
that the bass is driven across both channels in a "bridge" mode. if
one channel isn't connected - then the bass power will be enormously
reduced and the muddy effect wont be as bad.


The effect of it being loud and adjusting down is indeed due to the
AVC adjusting the volume level automatically to keep it constant.

If you leave the turntable sit with no record playing - it will turn
itself UP and when you then start playing - it will turn progressively
down to level things out.

When amplifier its unmuted by the machine - the level starts out about
midway in order to avoid this problem

That brings back memories.... lots of gooey surrounds I've had to deal
with..

Don


"KLR" wrote in message
...
On 8 Aug 2004 14:52:13 -0700, (John Hayes) wrote:

hi, all-
still fighting the battle of the muddy bass. had the amp gone over,
soldering checked, connections cleaned. today when we installed the
cleaned up, the right channel sounds great when it's plugged in, the
left channel sounds great when IT'S plugged in, but together, the
muddy bass is back. we hooked an external turntable into the amp and
noticed that there is now an increasing in the volume output, and
increasing reverb. this is over the course of maybe ninety seconds. it
crossed my mind that maybe, just maybe, this may have something to do
with he feature of the "fade in" sound once the tone arm rests on the
turntable once a selection is made. any thoughts?
thanks-
john hayes



I had the same recently on an R-81. Bass was horrible and distorted.
Turned out that the edge surround of both bass speakers was totally
stuffed (in fact there wasnt any left). Replacing both the woofers
made the thing sound fantastic once more.

This is the unit before speaker replacement.
http://www.geocities.com/kenreed1999/R81Speaker.jpg

The reason that the problem isn't happening with one channel only is
that the bass is driven across both channels in a "bridge" mode. if
one channel isn't connected - then the bass power will be enormously
reduced and the muddy effect wont be as bad.


The effect of it being loud and adjusting down is indeed due to the
AVC adjusting the volume level automatically to keep it constant.

If you leave the turntable sit with no record playing - it will turn
itself UP and when you then start playing - it will turn progressively
down to level things out.

When amplifier its unmuted by the machine - the level starts out about
midway in order to avoid this problem


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The effect of it being loud and adjusting down is indeed due to the
AVC adjusting the volume level automatically to keep it constant.

If you leave the turntable sit with no record playing - it will turn
itself UP and when you then start playing - it will turn progressively
down to level things out.

so, this happened when the external turntable was engaged to test
things out, and in theory should not when the juke turntable is
operating? is there any way to adjust the AVC? is this located on the
amp?

(Ken G.) wrote in message ...
You have the speakers out of phase . remove the wires from ONE speaker
and reverse them

so it ISN'T an amp problem???

On 9 Aug 2004 04:00:09 -0700, (John Hayes) wrote:



The effect of it being loud and adjusting down is indeed due to the
AVC adjusting the volume level automatically to keep it constant.

If you leave the turntable sit with no record playing - it will turn
itself UP and when you then start playing - it will turn progressively
down to level things out.

so, this happened when the external turntable was engaged to test
things out, and in theory should not when the juke turntable is
operating? is there any way to adjust the AVC? is this located on the
amp?


Since the external turntable presumably is being manually operated -
there may be a significant delay time from when the amp gets unmuted
and the tonearm goes on the record. this "silence" will make the AVC
circuit "crank up" the volume substantially. Once it gets sound
through it will take time to wind down again.

When the jukebox is operating as designed - the mechanism unmutes the
amp at approximately the same time as the needle sets down on the
record. Also if the tonearm setdown position is correct so the music
starts promptly after needle is setdown - then the AVC shouldnt have
time to "crank up" and therefore will start at a pretty average level
rather than "blasting" and then turning down over a few seconds..


The AVC in Rowe amps isn't adjustable - unless you want to go changing
the values of resistors and or capacitors on the pre-amp board that
set the time delays and levels for this AVC rate and amount. I
wouldn't recomend doing this unless you know what you are doing and
have a schematic for that model of preamp.


---------------------------

Finally - unless you reversed one channel of the cartridge leads on
your external turntable - you are likely to get very little or no bass
as this cartridge lead reversal is necessary to make the amp operate
in bridge mode to correctly drive the woofer.


Finally - if the external turntable is sat on a surface near or in the
juke without proper suspension (like the coil spring and conical
rubber mount assemblies that the ROWE mechansm stands on) you will
certainly get awful reberb back through the system from the speakers
and cabinet vibrations getting back to the cartridge. (sort of like a
mechanical feedback). It would sound so poxy that it wouldnt be
funny.


The sound systems used in ROWE jukeboxes dating all the way back to
the first stereo units are in many ways very different to used in
conventional home sound systems, and to the uninitiated there are many
things that aren't always as they first seem to be.

Finally - unless you reversed one channel of the cartridge leads on
your external turntable - you are likely to get very little or no bass
as this cartridge lead reversal is necessary to make the amp operate
in bridge mode to correctly drive the woofer.

this is all very useful... but let me go back to the issue of one
channel sounding great as long as the other channel isn't engaged.
what would be the first order of business here?

On 9 Aug 2004 12:17:57 -0700, (John Hayes) wrote:

Finally - unless you reversed one channel of the cartridge leads on
your external turntable - you are likely to get very little or no bass
as this cartridge lead reversal is necessary to make the amp operate
in bridge mode to correctly drive the woofer.

this is all very useful... but let me go back to the issue of one
channel sounding great as long as the other channel isn't engaged.
what would be the first order of business here?




What were the results of trying the advice given previously in posts
by "Ken G" and myself ?

What were the results of trying the advice given previously in posts
by "Ken G" and myself ?

i'll try this out and get back in touch. many thanks-
j