Polarity Testing the Oppo BDP-95

Above is the output of my Oppo BDP-95 player playing my SoftPolarityTest CD track one, through single ended stereo outputs, as viewed on a Tektronix scope.

A friend has been asking me to test the output polarity of the Oppo BDP-95.  Long ago I made a polarity test by recording a B&K analog function generator.  I started with a square wave at 400Hz and decreased the duty cycle so I had only a positive series of pulses at 400Hz.  I originally recorded this at a fairly high level, so it was dangerous to use.  Well this time I altered that by reducing the level 18dB.  I recorded the disc onto a T.Y. CD-R using a MacBook Pro.  I call this SoftPolarityTest.  You perform the test by playing the recording and watching the results on an oscilloscope.  If the visible pulses go positive, this is correct polarity, or at least it is correct compared with my reference standard for polarity, a Sony 507ESD high end CD player made in the 1980's and all other CD players I have tested so far.

Each track lasts 20 minutes so there is little chance of error.  I skipped ahead to the second track, which is the same recording in reverse polarity:

Here is the Sony 507ESD with the disc inserted.

It took about 11 minutes to get the scope hooked up to the sony because it is at the bottom of a pile of equipment in a tight space.  Here is what track one (I double checked) looks like on the Sony:

Here is the Denon 5900 playing track one:

So all three players have the same output polarity.  If I remember correctly, I previously tested a Samsung DVD player and a Toshiba 5700 (a model not made by Samsung like later Toshiba's were) and they had the same polarity also.  These are the only disc players I have ever tested for polarity, and none have been different.  I believe that is because all the ones I have tested are correct.

Funky smell

From my first use, I've noticed a smell coming from the Marantz 2130 that I associate with deteriorating electrolytic capacitors.  I've smelled this smell mostly on older equipment that needs to be refurbished.  Though I was also wondering if a previous owner of this unit was a tobacco smoker.

Before installing the tuner, I washed off outer case and bare chassis areas.  The smell was still quite noticeable an annoying to me in the kitchen.  A lady friend did not smell it.

I put my hand on the top case of the Marantz, and my hand picked up the smell.  OK, so now it occurred to me it was mostly coming from the funky vinyl coating on the top cover.

I removed the cover again, leaving the tuner uncovered in it's rack spot, pushed back so I don't accidentally try to put my hand on top again.  Some say equipment sounds best with it's cover of, and it did seem a bit that way, I noticed more depth and spaciousness.  Despite the vinyl coating, the Marantz top cover vibrates when music is being played through the speakers.  That can't be good for a tuner using ceramic and SAW filters which operate through mechanical sound transmission.

I rubbed the cover off again several times with Everclear, then put outside for sun exposure during next day or so.  I've been thinking the bad smell is from oxidation, and perhaps coating the vinyl with Deoxit would help.

I'm thinking I could make a different cover out of some damping material.  Possibly a single flat plate for the top of the tuner would be sufficient, leaving sides open, but possibly with some extra protection for the front.  I don't like putting wood cases on equipment like this because it already runs quite warm and I think that would make it run too warm for long term.

More Marantz 2130 pictures

Well, as I expected, the underside of the Marantz 2130 is covered with circuit boards.  Combined with the RF and IF circuitry on top, there is quite a lot of stuff in this tuner.  I started examining underneath the tuner on Saturday night.

The power supply in middle center looks about as big as in a Kenwood 600T, however it should be noted this one here also supplies power for the scope.  There are some nice looking large Nippon Chem Con capacitors in that power supply, and nothing looks underrated, no sign of cooking (as with the undersized resistor in the Sansui 9900).  The MPX board is on the middle right. The board in left front is the buffer board which includes features such as high blend and the oscillator.  Somewhere the quartz lock board is tucked in.

Above is a closeup of the MPX board.  In there is a Hitachi HA11223 mpx chip with external switching transistors.  The big modules on left are 38Khz subcarrier filters...those need to filter down to 22Khz.  The MPX board uses a pilot canceler implemented with discrete circuitry to remove the 19Khz pilot from the output.

Above is a closeup of the power supply board.  There are 3 heatsinked semiconductors on the right, and one in a larger heatsink on the left.  In addition to the fuses on this board, there is a fuse on the case.

Above is a closeup of the buffer board.  Both the mpx and the buffer feature single 4558 output IC's and relatively large electrolytic capacitors.  I worried a lot about the black dot on the large capacitor near the center of the photo.  I wondered if it had been painted on and in fact it's hard to tell as there is no other sign of leakage than the back mark and a slight depression where it is.  If it was caused by having a leak once, it appears to be completely sealed now.  It turns out to be a capacitor in the oscillator circuit, so I'm not too concerned about it.  However, the entire tuner did have what I often consider the "bad capacitor" smell.  I doubt that it all came from the one above, but it might have.  I washed and dried the entire exterior case over the weekend, allowing each piece ample time to completely dry.  I wiped bare chassis metal, and transformers, and accessible parts of the scope.  Everywhere I wiped in picked up some brown, perhaps some previous owner was a smoker though it doesn't small like smoke as such, it smells like bad capacitors.  All the cleaning reduced but did not eliminate the smell.

At first, I had some trouble getting the bottom cover back on.  It's held in place with screws around the perimeter, and only goes on one way, but one of the screws, toward the backright corner near the RF connections, is extra long, and apparently intended to make contact with the metal of the RF shield.  It has to be jammed in just so or the cover cannot be screwed on as it bulges near that corner.  The bottom cover itself is rather thin metal to be supporting such a heavy unit--or even a light unit.  It flexes easily.  This appears to be another design feature.  When the unit is put down, the bottom metal panel flexes enough so that unless your surface is very uneven, all 4 hard plastic feet will touch the surface underneath them.  But don't pile too much equipment on top!  When I push down on the top of the tuner, I can feel the metal plate underneath giving slightly.  This could also be a cultish audio feature in the sense that the bottom metal panel is undamped and therefore "live".

I washed the bottom panel first, then let it dry overnight because I was going to bed anyway.  The next day I put the bottom back on, and then took the top off for washing.  At that point, I noticed a serious fault in the tuner.  The wire going to the tuner position indicator light is sagging down onto the IF board.  As you tune from low to high and then back down again, it catches on various parts on the circuit board, including the very critical and valuable SAW filters.  Over time, this could cause misalignment or serious and possibly unrepairable damage to the IF board, which is the very heart of this fine tuner and the key to its above average performance.

I was unable to find in the manual how this is supposed to be done.  Perhaps the wire originally was stiff enough that it didn's sag in the middle, or perhaps (and most likely) the wire was surrounded by a piece of heat shrink either from the dial side or the other side (the wire was originally attached to a wire clip on the cover of the RF unit).

Heat shrink might be the best solution, but it would require at minimum unsoldering the lamp without damagin the plastic, a very tricky operation.  That might have been why Marantz Service didn't fix this.  Perhaps the original heat shrink got damaged and was jamming the dial, so they just removed it, and didn't bother to replace, not realizing that the above problem could occur.

I came up with a fix that did not require any soldering.  I cut a nylon wire tie and placed it across the valley of the inside of the tuner from RF cover, where the now unused clip for the lamp wire is, over to the dial, where it is jammed between the circuit board and the dial plastic.  As the indicator moves across the dial, the wire tie supports it in the center about an inch from the circuit board at worst case (shown in picture).  Most of the time, it is much higher than this.  It took about an hour of tweaking to get it this good.  I still worry about a number of things, including the possibility that over time the vinyl covering on the lamp wire will wear off rubbing against the nylon tie.  But I suspect that won't happen fast, if at all, and hopefully just disable the lamp or blow a fuse.

Followup to Marantz 2130 review

I posted this followup to my early review of Marantz 2130:


Thanks! By some stroke of good luck, my favorite station KPAC turned on full
power Saturday, first time in 6 months, just in time for some tuner rolling all
weekend!

Contenders: Pioneer F-26, Marantz 2130, McIntosh MR78

F-26: Most transparent, most 3D imaging, neutral tone with slightly soft highs

Marantz 2130: Most pleasant, best at rejecting interference in widest wide,
quietest sounding, most musical and dynamic, slight midbass emphasis, softness
in mid highs but open in extreme highs.

MR78: Very clear sounding, uncolored, squeaky clean, but easily perturbed by
interference in wide causing grating sounds--same as with slight off-tuning.
Super narrow is a pin point.

MR78 had Modafferi Mod and alignment in 2001; F-26 rebuilt by ASL in 2011: 2130
aligned by Marantz authorized service in 2012. It still bugs me that wnen
Modafferi modded what was to become my MR78 he bragged (in the documentation)
about getting the adjacent selectivity up in wide mode...just the opposite of
what the tuner needs IMO.

I'm more and more impressed by the 2130. I think this is just below the top
tier of tuners like TU-X1 (by reputation and info, not tested by me) and better
than many acclaimed supertuners like Kenwood KT-8300 that I have some experience
with.

Though it only has 5 gang air capacitor, the specs, even the RF specs, beat
KT-8300. I'm not sure if that's really true, but it does work better for me
primarily because of better quieting curve. RF specs are as good as L-02T and
audio specs fall just shy of L-02T mainly in separation, where the Marantz still
does an impressive 55dB at 1Khz and 50dB across the audio band. Stereo THD is
at 0.07%.

One thing that I think may be very special about the 2130 is how wide the wide
IF is, and maybe something about how it's tuned at the cutoff points, and
likewise the detector, in ways that are similar to 20B, which has similar sound
but much less sensitivity.

The 2130 wide is so wide that when you tune from one station to another 400Khz
away, with muting and lock disabled, it nevertheless snaps from one station to
the other with relatively small patch of noise in between. Slight off-tuning
has almost no effect, in fact you can be tuned more than 100Khz off and there's
still no splatter (though you've lost Stereo). Capture Ratio is specified as
0.8dB. I think this is why the Marantz shrugs off inteference better than the
others and always sounds dynamic, musical, and pleasant.

The narrow is nicely narrow, like other good tuners, but might be even more cool
if it were as narrow as MR78 super narrow. You can see images corresponding to
very weak stations on the scope, and that helps tune them in, but the lack of
ultimate selectivity keeps it from matching the MR78 in picking them up. The
Modafferi modded MR78 might also have more ultimate sensitivity even if not as
steep quieting. I'm now thinking a filter mod for the Marantz narrow might
indeed be a very good idea. But I don't want any changes to the wide IF.

For now, I'm keeping the transparent and 3D Pioneer in my living room for my
electrostatic speakers, but the Marantz is just the ticket for my Kitchen radio
shack which plays on good dynamic speakers. The MR78 goes back into the pile.
I've rarely had so much fun listening to FM.

Early Review of Marantz 2130

I posted this review to FMTuners on Monday April 16:

I like the sound of the Marantz 2130, it performs well, has almost every feature
found on FM tuners including, of course, a scope. The scope was why I bought
this tuner, after thinking that the scope on the 20B was too small to show
anything interesting about my favorite station KPAC. Actually, my 20B badly
needs a whole refurb, it makes occasional popping sounds, and the scope display
just has shrunken smaller than it should be, even with the small scope onboard.

This is a relatively accurate sounding tuner, and in that sense unlike the 20B
which I consider more of a musical instrument which somehow enhances
tunefulness. The 2130 is quiet and sensitive, quieting seems to be in same
ballpark as Pioneer F-26, still my reference tuner. The Marantz is easier to
play with, however, if you are exploring the dial, because all the controls,
including variable muting and variable output, IF bandwidth, high blend, mono,
and the quartz lock switch are on the front panel. I've long suggested I wanted
onboard attenuator rather than muting and here it is. I suggest using the
onboard volume control as a temporary attenuator while tuning, then turn it back
to 100% when fully tuned. It should not be used as system volume control
because it does not have perfect tracking between channels and there is
considerable image shift at the bottom end, just like almost all potentiometers.
Also, the quartz lock should be kept defeated as it tends to pull stations
slightly off center, even on my freshly authorized service center aligned unit.

About the sound, it's definitely on the warm side, but sounds open in the highs
as well. I'm wondering if there's small boost in the midbass and upper highs
above 6Khz. But it sounds very pleasant and not overdone and musically
enhancing, if indeed there are any frequency response tricks at all. I
generally think Kenwood tuners have a slightly brightish sound, I often think
this is honest accuracy, but it's not always appealing. Pioneer tuners seem to
get the balance right on, better midrange. The Marantz steps one step more away
from the classic bright Kenwood sound as typlified by KT-7500, but still has an
open sound, not sounding rolled off at all.

I greatly preferred the sound of 2130 to 600T. The 600T sounded coarse, grainy,
and dry compared with the Marantz. I confess my 600T has never been aligned and
possibly needs some alignment, even though the Pulse Count detector may need
less frequent alignment than any other design, and my 2130 was just aligned by
Marantz service center. OTOH, my 600T has been refurbed, and the Marantz
hasn't. But I have also been coming more and more to agree with those like
Anonymous Dave who say that old Kenwood Pulse Count detectors just don't get it
right. IMO, they weren't using a high enough 2nd IF frequency, and for that and
other reasons there is just too much information loss with that kind of system.
Less noise, less need for alignment, but less information too.

Overpriced? I've been shocked by the relatively low recent sale prices of such
all time greats as TU-X1 and L-02T, while it seems that people selling Marantz
tuners, especially 20B and other scope units, have been climbing higher almost
to reach them, and I think that's insane. But I like the sound of 2130 much
better than 600T, I believe they sold for about the same price in 1978, and the
Marantz has a scope. What's a scope worth? Well you can get nice used
professional scopes relatively inexpensively, but it's not easy to keep one of
those integrated with a hifi system. They're generally too big, and they always
find different uses right away. A dedicated scope would be nice. Nowadays
those go for high prices too. I just lost a bid on a Kenwood KC-6060A scope
which sold for $750. Mac MPI3's are listed for about $1000. BTW, I'm thinking
now that a scope could not be replaced by LCD display. It' has to be super fast
reacting, and show microscopic fuzz lines, to be useful.

Even if you have one of those nice hifi scopes, it takes one more equipment
space. I'm running out of equipment space in all my systems. Having the scope
integerated into the tuner, even if it's only a small scope, is nice. That way
it's always there, and it doesn't take more space. It makes for a very
reflexive tuning experience, you can see each station go by as you're spinning
the dial on the "multipath" display. Plus there's the very interesting L/R
display, which can expose some of the tricks being pulled as well as how much
separation you are getting. Plus, it's fun, lots of fun, and I think that's
important too.

I've heard these things can get filter mods and become top DX'ing machines after
that. I'm not really sure how much this tuner is limited by the lack of
narrowness in the "narrow" position, it's already pretty selective. Somehow I
doubt this has the kind of bulletproof or pristine front-end that the tuners
more praised here do, and that may be more of a limitation for ultimate dx'ing.
It *seems* plenty sensitive too, but there are most likely much quieter front
ends. OTOH, I think the air capacitor sets this above most varactor-based
tuners right there in most cases. FWIW, Marantz claims 110dB IMRR vs only 85
for my forthcoming L-1000T, I'm beginning to think that is a key spec for
musicality, keeping RF grundge out of the audio, so maybe this is more of a
sound quality spec even though it typically appears in the RF section specs.

Thoughts about modern vs vintage tuners

I posted this to FMTuners:


Substitute "Kenwood L-02T" or "Sansui TU-X1" for 10B, then you have interesting
question.

Answer: Accuphase continues to march on making superb tuners for analog FM
broadcasting, other old names have either thrown in the towel altogether or
aren't spending enough money on it anymore. There is little chance that the
circumstances that led to the great tuner race of the late 1970's to early
1980's will occur again. There are a few recent fairly serious tuner makers now
like Magnum Dynalab, and a whole cottage industry of tuner restorers, modifiers,
and tweakers. And there is a huge glut of old units that have been cast off,
just waiting to be modified, restored, etc. And most of them can be made to
sound as good or better than 10B

HD digital subcarrier broadcasting squeezes your actual bandwidth/bitrate down
to practically nothing. The information in a full analog broadcast is
potentially greater than CD. It relies on psychoacoustic masking like most
lossy compression systems. Such masking isn't perfect, the ill effects can
easily be heard. But those who just want low noise can be fooled.

I've never hard a 10B, but my current opinion is that the 20B was Dick
Sequerra's best tuner because it gets key details right. A single RF amp, air
capacitor tuning, and very wideband IF and detector. This SS tuner dates from
mid 1960's early SS but is still a classic that other designers should know
about. OTOH, 10B uses two RF amps and is prone to IM, in fact the IM is always
there, has a relatively narrow "compromise" IF, and a vestigal MPX decoder that
throws away half of the stereo subcarrier to reduce noise, not a good place to
start IMO. But there are a limited number of 10B's, it has a legend and a cult,
and it's cool looking and I've bid on them too.

There is a lot of potential wrt digital RF sampling and processing, but other
than Accuphase, nobody is pushing the technological envelope for receiving
analog broadcasts in greater true fidelity. Digital Tuners are generally made
for car radios and generally focus on eliminating noise through dynamic noise
suppression and other trickery that doesn't make for the highest fidelity. In
general, there is no substitute for linearity and wide bandwidth, but someone is
always trying to sell one.

Thoughts about Day-Sequerra and other tuners

I sent this email also:

The D-S "FM Reference" isn't any fun, IMO, without the Panalyzer.  Few models had that because it doubled the price.  I'm not sure that one does.  It is said to be a very good performing tuner.  There are so many different sequerra models over the years I'd like to hear some for myself.  The Reference got very good reviews in Stereophile, fwiw, better than what Accuphase had in 1992 they said.  It uses better BB audio chips than japanese tuners (other than recent accuphase) and has balanced output.

Nowadays D-S makes professional broadcast monitors, and their specialty seems to be monitoring HD radio with all possible options.

The original Sequerra Model One only came with the Panalyzer.  There's been one of those listed on eBay for $5000 obo for several weeks now.

It's a steep price to pay for by-many-accounts-lousy tuner with spectrum analyzer.  I got boat anchor HP unit designed for certifying cell phones that has spectrum analyzer that works reasonably well in 100Mhz band, I can get FM spectrum displays that look similar to Sequerra.  That cost me $400, but far too inconvenient to use mostly.  Now I was thinking, if I could have some gizmo that sampled the LO on my Marantz, sent the info to the HP serial port,  HP generates appropriate display, then sends it back out to marantz scope.  Actually, though, the HP has NTSC video output, not X-Y, and the unit has very annoying lag and menued controls.

I think 10B had 4" scope, the 20B has 2" scope, and the 2130 has 3" scope.  The scoped sequerras have have 5" scopes, the nicest of all.

Nice interface.  What they needed was user replaceable module for the actual tuner.

I'm now of the opinion that 10B wasn't Marantz best tuner.  20B and 2130 were.  The 20B especially exemplifies the correct classic design principles: single RF amplifier, extremely wideband IF and detector.  By all accounts, the 10B has relatively narrow "compromise" IF, they bragged about (hypothetical) 150dB selectivity, and dual RF amplifiers that are very sensitive but infamously prone to IM, and quasi-vestigal MPX which throws away half of the stereo infomation.  I think the 2130 tames its two RF stages by virtue of well tuned AGC with dual gate Mosfets.

Dick Sequerra was on to something with the mostly underappreciated 20B.  But the virtue of wide bandedness was lost in the noise of selectivity spec wars of the 1970's.  His second tuner was better than the first.  But reaching for the gold ring, with the Sequerra Model One, he reached prematurely to make a great tuner with varactors, which didn't work.