[[email protected]]

In sum, I have a new Denon audiophile amplifier. I sensed a balance
problem, left channel sounds a bit hotter than the right through the
speakers and also the headphone output. I measured voltage at the
speaker outs while feeding in a 1kHz reference tone and determined
that more voltage is indeed being put out from the left side.

I opened the unit and found what appears to be some type of adjustment
pot on each of the unit's two main circuit boards ("L-ch" and "R-
ch"). I am not sure if these are output trim adjusters or something
else (I'm not a tech).

Before I touch anything, I'd really appreciated a little advise
here... should I make an attempt and turn one of the adjusters
slightly to see if I can put the unit back into balance? Or might
these adjusters be something that a novice like me with no hi-tech
electronic test gear should NOT touch under any circumstances?

I REALLY do not want to ship this heavy unit away just so that Denon
can sit on it for three months while they eat donuts, and all the
while I have no amp to use.

For more details and good photos of the "adjustable pots" I speak of,
click he
http://www.gearslutz.com/board/1232739-post7.html

Thanks for the help.

[Scott Dorsey]

wrote:
In sum, I have a new Denon audiophile amplifier. I sensed a balance
problem, left channel sounds a bit hotter than the right through the
speakers and also the headphone output. I measured voltage at the
speaker outs while feeding in a 1kHz reference tone and determined
that more voltage is indeed being put out from the left side.

I opened the unit and found what appears to be some type of adjustment
pot on each of the unit's two main circuit boards ("L-ch" and "R-
ch"). I am not sure if these are output trim adjusters or something
else (I'm not a tech).

You need the service manual. The service manual will tell you. More
likely this is a bias control, especially if it's near the output
stages.

Before I touch anything, I'd really appreciated a little advise
here... should I make an attempt and turn one of the adjusters
slightly to see if I can put the unit back into balance? Or might
these adjusters be something that a novice like me with no hi-tech
electronic test gear should NOT touch under any circumstances?

It's new. Take it back to the dealer and demand a replacement.
You DO want to get a copy of the service manual just to have on hand,
though.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[[email protected]]

Hi Scott....

I bought the unit mail order, and there are no Denon shops near me, so
it'll be a hassle for me to have it repaired or replaced... was hoping
to avoid this.

I will try to get my hands on a repair manual.

In the meantime, here's a question... if indeed the adjusters I see
are NOT output level trim pots, then HOW does one match the output
levels of the left and right channels for proper balance? I do not
see any other adjustments on the inside.

Thanks.

[Scott Dorsey]

wrote:

I bought the unit mail order, and there are no Denon shops near me, so
it'll be a hassle for me to have it repaired or replaced... was hoping
to avoid this.

I will try to get my hands on a repair manual.

Welcome to the marvelous world of cheap box houses. You get what you
pay for.

Send it back. This could be a symptom of another more serious problem.
You won't know until you do full bench testing, which you don't have the
gear to do.

In the meantime, here's a question... if indeed the adjusters I see
are NOT output level trim pots, then HOW does one match the output
levels of the left and right channels for proper balance? I do not
see any other adjustments on the inside.

You find out what causes the imbalance. That usually means cutting a
couple traces on the PC board to break feedback loops, then putting a
1KC sine wave into both channels. Then you go stage by stage with a
scope and look for the point at which the two channels become different,
then you start looking at that stage.

Modern amplfiers generally have so much overall feedback that gain
differences between channels disappear. As a result, there aren't
usually adjustments. The thing is, this feedback can hide all kinds
of things... you can have an output transistor completely out and
all you'll notice is a slight channel imbalance until you start running
at high levels.

If you aren't prepared to take it to a GOOD bench tech (and I will say
that because there is so much DC coupling on these things, it takes a
good technician to deal with them) and pay for a couple hundred bucks
of bench testing to see what is up, then send it back.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[[email protected]]

Thanks Scott, I appreciate the advice. I guess this baby is going
back.

[John L Rice]

"Scott Dorsey" wrote in message
...
wrote:

I bought the unit mail order, and there are no Denon shops near me, so
it'll be a hassle for me to have it repaired or replaced... was hoping
to avoid this.

I will try to get my hands on a repair manual.

Welcome to the marvelous world of cheap box houses. You get what you
pay for.

Send it back. This could be a symptom of another more serious problem.
You won't know until you do full bench testing, which you don't have the
gear to do.


Hi Scott and eagle123 . . or 666666 or who ever you are ;-)

Just FYI I posted on GearSlutz the following :

I did a search and found a place you can download a service manual :
http://fileshare.eshop.bg/downloadsm...A-2000IVR.html
It's compressed in RAR format so you may need to also get another program to
unzip it if you don't already have one. I'd say it will be worth the effort
though.

John L Rice

[John L Rice]

Hi Scott and eagle123 . . or 666666 or who ever you are ;-)

Just FYI I posted on GearSlutz the following :

I did a search and found a place you can download a service manual :
http://fileshare.eshop.bg/downloadsm...A-2000IVR.html
It's compressed in RAR format so you may need to also get another program
to unzip it if you don't already have one. I'd say it will be worth the
effort though.

John L Rice

Sorry, try this link :
http://fileshare.eshop.bg/downloadsm...A-2000IVR.html

[Arny Krueger]

wrote in message
ups.com
Hi Scott....

I bought the unit mail order, and there are no Denon
shops near me, so it'll be a hassle for me to have it
repaired or replaced... was hoping to avoid this.

I will try to get my hands on a repair manual.

In the meantime, here's a question... if indeed the
adjusters I see are NOT output level trim pots, then HOW
does one match the output levels of the left and right
channels for proper balance? I do not see any other
adjustments on the inside.

Gernally, none should be needed. Most modern equipment has no internal gain
or channel balance adjustements. The internal gain should be set with
precision resistors with 1% or better tolerance.

[William Sommerwerck]

Doesn't your control center have some sort of balance control on it? If so,
use it!

If you have no technical background, don't even _think_ about adjusting this
unit. The pot is almost certainly a bias control, NOT a gain adjust. Most
amps set overall gain with 1% resistors in the feedback loop -- any
differences in channel gain should be minor and inaudible.

Does your amp have input level pots? If so, check them.

[[email protected]]

Thanks for all the input guys.

Here's a little more info for general interest and for curious
techies:

Note: this is an integrated "audiophile" type amp. It has one big
volume knob on the front that controls both stereo channels. It also
has a section with tone and balance controls... BUT, this tone /
balance section can be switched OUT of the path for a pure direct amp
signal... and this is how I like to use it... sounds best this way.

I just ran the 1kHz test tone into the amp again and measured the
voltage at the speaker outputs at various settings on the main volume
knob of the amp (tone and balance controls bypassed).

With the volume knob set at anywhere from about 5% to 35% of its total
travel up from "zero", the difference in voltage between the left and
right channels is close to 20%, the left side always being hotter.
For example, with the volume knob at about 25% up from "zero", the
left channel is putting out 0.980 volts and the right, only 0.800
volts.

As the volume knob gets closer to the 50% mark... between about 35%
and 45%, the difference in voltage between the two channels gets
smaller, down to around 5% difference.... left side still always the
hotter side.

When the volume knob is at exactly 50% of its travel and above, the
voltage difference gets even smaller, in some cases the right channel
actually gets a tad hotter than the left, and the differences in
voltage between the two channels remains pretty small, in terms of
percentage, all the way up to full blast where each channel is putting
out almost 50 volts with less than a 1 volt difference between them.

When I use the amp, whether using monitor speakers (Dynaudio BM15s) or
headphones (assorted pro headphones) , the volume knob is always
between about 10% and 40% of its full travel, never higher. Any
higher would be "too loud" and would damage the speakers. So, I am
always using the amp in the range where the imbalance is greatest.
(The amp is rated at 80W + 80W @ 8ohm, and 160W + 160W @ 4ohm).

I can assure you that the imbalance is very audible, at least to the
audio professional... I certainly cannot tolerate this on a brand new
expensive amp.

So... based on this info... any more theories as to what the problem
may be? Any other thoughts, comments?

Thanks.

[Laurence Payne]

On 15 Apr 2007 20:19:46 -0700, wrote:


When the volume knob is at exactly 50% of its travel and above, the
voltage difference gets even smaller, in some cases the right channel
actually gets a tad hotter than the left, and the differences in
voltage between the two channels remains pretty small, in terms of
percentage, all the way up to full blast where each channel is putting
out almost 50 volts with less than a 1 volt difference between them.

If this wasn't a newish amp, presumably still under warranty, I might
be tempted to resolder connections around the volume control. But it
may be something more serious. ARe you happy to void your warrenty?

[William Sommerwerck]

With the volume knob set at anywhere from about 5% to 35% of
its total travel up from "zero", the difference in voltage between
the left and right channels is close to 20%, the left side always
being hotter. For example, with the volume knob at about 25%
up from "zero", the left channel is putting out 0.980 volts and the
right, only 0.800 volts.

rest of data which should have supplied in original post snipped

What you have is a mistracking volume control. None is ever perfect (except
for switched attenuators), but the nearly 2dB difference you measure is
large for an "audiophile" product, and would be audible to an attentive
listener. Unfortunately, if Denon doesn't spec the channel balance, you're
hosed, because they're not legally obliged to fix a problem that isn't a
problem. Look at the spec sheet. Does it spec channel balance?

I find it interesting that the bypass switch (supposedly) bypasses the
balance control, as that control should be sonically benign. Check again to
see whether it's working in the bypass mode.

I'd recommend you contact both Denon and the dealer as soon as you can.
Don't wait.

[[email protected]]

On Apr 16, 5:54 am, "William Sommerwerck"
wrote:
Look at the spec sheet. Does it spec channel balance?

I do not see a balance spec anywhere.

I find it interesting that the bypass switch (supposedly) bypasses
the balance control, as that control should be sonically benign. Check
again to see whether it's working in the bypass mode.

The "bypass" switch bypasses both the balance control AND the tone
controls (bass and treble knobs) altogether. I checked again... this
bypass switch definitely bypasses the tone and balance controls.

When the tone and balance controls are in the path, the sound gets a
tad bit hotter and brighter (with balance and tone controls set to
detented "zero".) For the heck of it I measured the voltage output
with the bypass out compared to with the bypass in... with the bypass
out (tone and balance controls in the path), the voltage was always a
bit higher.

The balance control knob, when set to zero, does not change balance
when in the path compared to being out of the path. In order to get
the balance to sound "correct" to my ears (when at say 30% volume), I
can switch the balance control into the path and turn it to about 1
o'clock. I went back with my voltmeter and adjusted the balance knob
until the output of both channels showed almost identical voltage, and
alas the resulting balance knob position was about 1 o'clock.

You're scaring me... Denon better take care of this. And if I do wind
up getting royally hosed here somehow, perhaps a good tech could mod
the unit and swap in a better volume control... even if it was an
outboard fader box piggy-tailed out of the main chassis or
something... that would probably be cheaper than the loss I'd take
trying to sell this thing used now.

One note... this amp has a motorized volume control that can be
adjusted via a remote, which is a very handy feature for me since the
amp resides in a spot that can sometimes be inconvenient to get to.
If I have to mod the volume control, I guess I'll lose that nice
feature. I've never had trouble with Denon before... and this amp,
other than the balance issue, has been excellent so far... I am
enjoying its performance, very fast, crisp, detailed and dynamic, lots
of gusto ... I like it a lot. Sure hope this balance issue can be
resolved.

I'll do my best to get Denon to fix it or take it back. Calling today.

[Laurence Payne]

On 16 Apr 2007 05:09:33 -0700, wrote:

On Apr 16, 5:54 am, "William Sommerwerck"
wrote:
Look at the spec sheet. Does it spec channel balance?

I do not see a balance spec anywhere.

I find it interesting that the bypass switch (supposedly) bypasses
the balance control, as that control should be sonically benign. Check
again to see whether it's working in the bypass mode.

The "bypass" switch bypasses both the balance control AND the tone
controls (bass and treble knobs) altogether. I checked again... this
bypass switch definitely bypasses the tone and balance controls.

When the tone and balance controls are in the path, the sound gets a
tad bit hotter and brighter (with balance and tone controls set to
detented "zero".) For the heck of it I measured the voltage output
with the bypass out compared to with the bypass in... with the bypass
out (tone and balance controls in the path), the voltage was always a
bit higher.

The balance control knob, when set to zero, does not change balance
when in the path compared to being out of the path. In order to get
the balance to sound "correct" to my ears (when at say 30% volume), I
can switch the balance control into the path and turn it to about 1
o'clock. I went back with my voltmeter and adjusted the balance knob
until the output of both channels showed almost identical voltage, and
alas the resulting balance knob position was about 1 o'clock.

You're scaring me... Denon better take care of this. And if I do wind
up getting royally hosed here somehow, perhaps a good tech could mod
the unit and swap in a better volume control... even if it was an
outboard fader box piggy-tailed out of the main chassis or
something... that would probably be cheaper than the loss I'd take
trying to sell this thing used now.

One note... this amp has a motorized volume control that can be
adjusted via a remote, which is a very handy feature for me since the
amp resides in a spot that can sometimes be inconvenient to get to.
If I have to mod the volume control, I guess I'll lose that nice
feature. I've never had trouble with Denon before... and this amp,
other than the balance issue, has been excellent so far... I am
enjoying its performance, very fast, crisp, detailed and dynamic, lots
of gusto ... I like it a lot. Sure hope this balance issue can be
resolved.

I'll do my best to get Denon to fix it or take it back. Calling today.

So how does it track when the balance control is at 1 o clock?
Alternatively, what settings on the tone controls match the
straight-through sound? Don't kid yourself the straight-through
route includes no eq shaping - it's integral in the circuit design.
And plenty of eq was applied to the recorded signal earlier in its
existence. Maybe you're pining for an internal balance control when
you already have a convenient external one?

Or send it back. I don't think you've revealed exactly what model amp
we're talking about. Is it a secret?

[Scott Dorsey]

wrote:

When I use the amp, whether using monitor speakers (Dynaudio BM15s) or
headphones (assorted pro headphones) , the volume knob is always
between about 10% and 40% of its full travel, never higher. Any
higher would be "too loud" and would damage the speakers. So, I am
always using the amp in the range where the imbalance is greatest.
(The amp is rated at 80W + 80W @ 8ohm, and 160W + 160W @ 4ohm).

I can assure you that the imbalance is very audible, at least to the
audio professional... I certainly cannot tolerate this on a brand new
expensive amp.

So... based on this info... any more theories as to what the problem
may be? Any other thoughts, comments?

You got a cheap volume pot that doesn't track very well. Life is like
that. In terms of pots, you get what you pay for, and these days
good ones are not cheap.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[[email protected]]

On Apr 16, 8:16 am, Laurence Payne lpayne1NOSPAM@dslDOTpipexDOTcom
wrote:
...So how does it track when the balance control is at 1 o
clock?...Maybe you're pining for an internal balance control when you
already have a convenient external one?

Everything sounds fine if I adjust the balance control to about 1
o'clock. But, for an expensive "audiophile" amp, I feel I should not
need to keep the external balance control at 1 o'clock all the time in
order to make things sound correct. Plus, I do prefer the overall
sound of the amp better when the balance and tone controls are
switched out. But, if things do not turn out well here, I may just
have to live with keeping the balance control switched in and at 1
o'clock. Plus this would be a pain since the balance changes a bit as
the volume is increased.

I don't think you've revealed exactly what model amp we're talking
about. Is it a secret?

No secret. It's a new Denon PMA-2000IVR integrated stereo amp... 80W
per ch @ 8ohm, 160W per ch @ 4ohm... high current MOS push-pull...
here's the brochure and owner's manual in pdf:

http://oldusa.denon.com/catalog/pdfs/pma2000ivr.pdf

http://oldusa.denon.com/catalog/pdfs...0IVR%20DFU.pdf

Anyone have any experience with this amp, either sonically or
technically?

[[email protected]]

On Apr 16, 5:54 am, "William Sommerwerck"
wrote:
...but the nearly 2dB difference you measure is large for an
"audiophile" product...

Just curious, how do you arrive at a "2dB difference" (as posted
above)? Did you compute this based on the voltage data? I know I had
said that I had a difference in voltage between the channels of close
to 20%, or in one case, a difference of about 0.180 volts. Please
bare with me, I'm not a tech, just trying to learn a little bit so I
can speak somewhat intelligently with whatever Denon tech I should get
on the phone.

[Laurence Payne]

On 16 Apr 2007 06:37:08 -0700, wrote:

I don't think you've revealed exactly what model amp we're talking
about. Is it a secret?

No secret. It's a new Denon PMA-2000IVR integrated stereo amp... 80W
per ch @ 8ohm, 160W per ch @ 4ohm... high current MOS push-pull...
here's the brochure and owner's manual in pdf:

http://oldusa.denon.com/catalog/pdfs/pma2000ivr.pdf

http://oldusa.denon.com/catalog/pdfs...0IVR%20DFU.pdf

Anyone have any experience with this amp, either sonically or
technically?

Quite an expensive toy! Not quite the full-blown audiophile bull****
in the brocure, but some inmressive pseudo-science none the less!
Never mind. They have to do that to sell them, I'm sure it sounds
good anyway.

It's under warrenty. Send it back.

[William Sommerwerck]

I'll do my best to get Denon to fix it or take it back.
Calling today.

Suggestion... One of the best ways to get someone to do something is not to
_insist_ that they do it. Most people react badly to being pushed up against
the wall.

"Hello, Denon? I just purchased one of your SuperWhammo amplifiers, and it's
not behaving the way I expect an amp of that quality to perform. The
channels consistently mistrack by about 2dB over the volume settings I
commonly use, and I don't want to switch in the tone and balance controls,
as I don't like what they do to the sound. What do you suggest?"

Or something like that. Keep it low at first. You can always get angry
later.

[William Sommerwerck]

...but the nearly 2dB difference you measure is large for an
"audiophile" product...

Just curious, how do you arrive at a "2dB difference" (as posted
above)? Did you compute this based on the voltage data? I know I had
said that I had a difference in voltage between the channels of close
to 20%, or in one case, a difference of about 0.180 volts. Please
bare with me, I'm not a tech, just trying to learn a little bit so I
can speak somewhat intelligently with whatever Denon tech
I should get on the phone.

From years of experience, I know what voltage ratios correspond to what
power ratios. The difference in voltage is about 25%, which is about 2dB.

[[email protected]]

On Apr 16, 8:59 am, Laurence Payne lpayne1NOSPAM@dslDOTpipexDOTcom
wrote:
http://oldusa.denon.com/catalog/pdfs/pma2000ivr.pdf
http://oldusa.denon.com/catalog/pdfs...0IVR%20DFU.pdf
...Not quite the full-blown audiophile bull**** in the brocure, but
some inmressive pseudo-science none the less! Never mind. They have
to do that to sell them, I'm sure it sounds good anyway...

I use Halfters in the studio, but just wanted something decent and
something different for my living room at home. Was sick and tired of
listening to the cheap crap Sony home theater amp that my wife
bought. I know essentially zero about the "audiophile" market, I only
have experience with "pro audio".

The whole "audiophile" thing is totally new to me. I'm not really an
"audiophile" kinda guy, but... in this case, I wanted something better
than the typical consumer crap sitting over at the local electronics
super-store, but needed something a bit tamer and more user-friendly
than "pro audio".... somehow I found myself in audiophile-land, for
better or for worse.

I was almost going to throw a Hafler pro amp into the living room, but
that would not have worked out well with the wife. Things have to
look nice, fit nice and be easy to use.

I have used Denon products for years in the studio, cd players etc,
never a problem. So, in trying to find a "decent" stereo amplifier
for the home, I happened to notice that Denon had this PMA-2000IVR
offering, was the right wattage, had all the features I wanted, so I
figured I'd just take a chance. I was not dazzled by the bull****
psuedo-science advertising, quite honestly, I don't even understand
half of it, just wanted something that sounded good. Sometimes you
get lucky when you roll the dice... I know it would be way better than
what I had anyway.

This Denon amp DOES sound good... in fact, it sounds excellent in my
opinion. Maybe it wouldn't blow away the most critical audiophile
nuts out there, but I'm pretty fussy about sound, and I give it a
general thumbs up... except for the balance problem.

This amp, through my Dynaudio BM15s, is making me very happy, at least
as an extra system in my house where my wife is blasting the Rolling
Stones half the time anyway. What a huge improvement over the Sony
home theater amp we had before (and it was a "top of the line" one
too)... this new Denon is probably twice as detailed and twice as
dynamic... it just sounds damn good, period. Will probably experiment
with different monitors over time, for now the BM15s provide a good
all purpose full range for general user-friendly listening.

Are there any other current offerings in terms of good stereo
integrated amps that would be a good replacement for this
PMA-2000IVR... for under $1,200 or so? Someone was pushing me toward
a Bryston set-up, but that was considerably more expensive (amp plus
separate pre-amp which I'd need). Unless I missed something, I don't
think there are many or any other units out there (new) that offer the
features / sonic quality of the Denon for the price... at least in
terms of integrated amps with built-in controls, remote volume
control, etc.

I guess this Denon is now proving to not be as high quality as I had
hoped (apparent cheap volume control), but at least the rest of it
seems good. Hopefully Denon will find it in their hearts to either
give me a new unit or swap the volume control for one that is simply
better. Ok, "cheap" volume controls can be inaccurate... but gee,
I've owned and used tons of stereo amps since the beginning of time
and I never remember using a unit that had such a severe balance
issue. Even the bogus Sony home theater amp... to my ears, the
balance is perfect on that thing... I don't see why the Denon should
not be as good.