I finally bought something I've wanted for more than 20 years, a McIntosh MR 78,
and I love it. It's a superb tuner in every way, the best I've ever owned
(unseating both my Sansui TU-9900 for DX'ing and my Kenwood 600T for sonics).
It's a super DX tuner and a super audiophile tuner in one well-designed box.

I went the whole number and got a unit in "near mint" condition (recently
cleaned by a perfectionist Mac dealer) and with the Modafferi Update (done in
2000). I haven't yet gotten the paperwork for the Modafferi Update, and I have
no way of comparing the unit before and after. But I can tell you that with the
update, it's great. I'm sure part of that has to do with it having been aligned
recently by Modafferi himself. This is probably better than if you bought an
MR78 brand new. Considering they cost as much as $1600 new in 1976, the one I
got for $1200 on eBay with a recent Update is a great deal in my opinion.
Without the update, they sometimes sell for under $800, which is also a great
deal in my opinion. After the MR 80, McIntosh stopped even trying to build "the
ultimate" in super tuners because they would have gotten too expensive to sell
to enough people to make money. (One such estimate of price was "5 figures.")

The MR 78 sensitivity and selectivity are outstanding. Even in the widest IF
mode, I've been getting stations that required the narrowest mode on other
tuners (100 and 200 miles away). In the Super Narrow mode I've been picking up
stations all over the dial I've never heard before. Unfortunately, with my
kitchen wall mounted whip antenna, none of those new stations are actually
listenable, but I have great hopes for what can be accomplished with a high gain
yagi which I hope to put up in the next year or so. I have the good fortune of
living in San Antonio where the troposhere is amazing, which is why I can get
far away stations even with a nondirectional indoor antenna.

My favorite local station, a public radio station with 24 hours classical music,
sounds quieter and better than it had sounded on my 600T. I would have thought
I was getting full quieting with the Kenwood (the meters read 61dBf and no
multipath) but somehow the MR78 is even quieter and yet has equally extended
high frequencies (if not more extended). Even when lightning knocked the
station down to auxiliary power yesterday (with a more than 20dBf loss), it was
still coming in noiselessly on the MR78 while a CT-1010 in another room was
becoming very noisy.

The seems no lack in bass, midrange, or highs with the MR78, and it even has a
certain "liquidity" (from lack of high frequency noise and distortion?) that I
was not expecting. By comparison the Kenwood 600T has a very fine grain, and
the Kenwood KT-7500 has boulder sized grain (in which many musical instruments
no longer sound like real instruments). The tubed Fisher KM-61 also sounds
grainless, but seems far less defined, like there is some stuff missing (though
you get what's most important).

I'm sure that when I get the performance measurments made by Modafferi it will
show essentially flat frequency response and vanishingly low distortion. I have
serious doubts that it gets much better than this. I believe it must be pretty
close to perfection already. Even if there are tuners with slightly better
measurements, they are probably not better by enough to be audible in a blind
test, so why spend big money chasing after them? (I'm thinking about those
spending $2,600 for a TU-X1 for example...and I have serious doubts than any
particular TU-X1 is even going to be better in the first place.) Those who have
denounced the sound quality of the MR78 are clearly wrong. It is audiophile
quality. It is the best sounding tuner I have heard, and I also own a few of
the ones they recommend.

The controls are great; the selectivity control is much easier to use than on
the Kenwood 600T because it's big and turns easily. Every control operates
without making any noise or short cut-out. The center tune meter is somewhat
more sensitive, and the multipath meter is much more sensitive than those on the
600T. I like the way the stereo light shows that there is a stereo pilot
whether you have stereo enabled or not (though there could be another light for
stereo enabled, as there are for filter and muting).

The glass front is nice, the only slightly dated look comes from the rectangular
plastic grill around the dial. With lights off, however, the unit is very
beautiful, and all the legends for the controls are lighted (in blue) through
the glass. It's wonderful to bask in the cool blue glow in a dark room. It's
also cool to look through the wire cages in back, where you see the labeled (in
gold) and enclosed filter modules, and a nice blue fiberglass-epoxy circuit
board. It's like audio jewels in a custom terrarium.

There are no 200Khz tick marks as on some other tuners, but with all other the
tuners I have the dial is off by about 100Khz or more anyway. (I think Mac left
the tick marks off so as not to require annual tweaks by perfectionistic Mac
owners.) With my MR78, tuning is about as close as you could guess by eyeball
between the evenly spaced 1Mhz tics. I'd rather the "log scale" had been
left out...another part of the slightly dated look.

I do miss having a calibrated signal strength meter and modulation meter (as
on the Kenwood 600T), but I'll take the better performing and sounding tuner
any day.

Many people think of the MR78 as lacking filtration for the 19Khz pilot and
38Khz carrier. That was true of the earliest production, units AD1001-AD5164.
The later units, AD5165 and beyond, and CG1001 and beyond, did have a 19Khz and
38KHz filter. I think of the later units as "MR78 B" though McIntosh choose
never to label them that way. My unit, AD7xxx, is clearly in the later series.

In addition to the added filter in the later units, there is also an emitter
follower to drive the output. The variable output adds only a 10K pot (not an
extra stage as with the Kenwood 600T). If you wanted to tamp down the high
frequencies a tiny bit (you will not want any more highs, IMHO), you could use
the the variable output and adjust it anywhere from full to -3dB. The effect
will also depend on how capacitive a cable you use. It will be a very subtle
effect; I think of this as an extra "audio pallette" control, not a high filter
per se. (The MR78 already has two very effective high filter settings for noisy
stations.) Modafferi puts new gold jacks on the fixed output, so it's clear
which output he wants you to use. I'm very happy with the fixed output.

Charles

Charles,
I have to agree with your comments about the MR78. I
got mine in very good condition (especially
cosmetically) back in February. I just had the full
Modafferi treatment done in June. (By the way, Richard
put the gold RCA connectors on both the fixed and
variable outputs, though this was done because of a
screw-up by audioclassics, read my post of 2 weeks ago
for the gory details ). I highly recommend you get
the yagi to explore the full potential of your tuner.

I promised this group I would give my impressions on
what improvements I noticed with the Modafferi mods.
First, the tuner has less drift on warming up.
Previously it would drift about the full width of the
center section of the tuning meter. Now the max drift
is about a quarter to half that.

Sound quality is great. It's hard to attach sound
differences since I can't A/B an unmodified MR78 vs
the modified. I can though compare the sound to a
Yamaha TX-930 I own. The Yamaha sounds much more
constricted or stuffy in the mid to high range. This
range has a crystal clarity on the MR78. Selectivity
is no contest. With just the narrow filter I can tune
stations on the MR78 that are impossible with the
Yamaha. I still have the super narrow position which
is able to zero in on even more stations. And yes the
three way stereo blend switch is very nice at
decreasing the noise on marginal stereo signals. I
wish I had more tuners to compare against. I envy
Charles in that regard. At some point I plan to
increase my collection of 'vintage' tuners (don't want
the wife to see this message though ;-).

Bill Corbin
AD 5421


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William,

Do you have any impressions of the sonic difference before and after the update
based on memory? At least such long term memories aren't likely to be biased by
level differences, assuming you adjust level up and down from time to time. Do
you believe it improved significantly, and, if so, in what way? I must confess
that many of my reports are based on such long term memories. "Rapid switching"
tests, which I find very tedious and confusing, can be equally subject to error
unless carefully controlled (blind and level matched, for example).

I've now discovered a new far away station I can get at listening quality even
on my lowly whip antenna, including one station from Houston over 200 miles away
from where I live in San Antonio.

One other amazing thing is how the updated MR 78 can get stereo on virtually any
signal, even very weak ones.

It's incredible how much audio transparency the updated MR 78 has. This is very
enjoyable on music. During pre-recorded messages, you can sometimes hear the
background hum and noise from the tape clearly. There's plenty of bass response
too, seemingly more than on any other tuner I have; it's got lively and tuneful
bass which I don't remember hearing on any other tuner through my small
modified LS3/5A speakers.

I wonder how your TX-930 compares with the famous Yamaha TX-950, the latter
being one of the few tuners to have Sanyo's top MPX chip (LM3450?), still
considered to be the best today. Even your TX-930 is bound to have a much later
generation chip-based MPX design than the MR78, so it's surprising how well the
MR78 does in comparison. I don't have any tuners with latest-generation MPX
designs. I recently made the mistake of buying a Pioneer TX-950 thinking it was
the Yamaha. It's a cheap early generation digital tuner. At least I didn't pay
much, only $19.95.

I see that among the things Modafferi *might* do in an update is replace
capacitors with polypropylene units, and "modify stereo decoder for higher slew
rate..." Do you know what was done more specifically?

Charles

William wrote:

Jim wrote:

Charles,
Is it LA 3450 or LM 3450 for the MPX chip? jim.....

Of course it's LA 3450.

Charles

--- In FMtuners@y..., Charles Peterson <charlesp@d...> wrote:

I see that among the things Modafferi *might* do in an update is

replace

capacitors with polypropylene units, and "modify stereo decoder for

higher slew

rate..." Do you know what was done more specifically?

See the RM mug shot and mods description here -

http://www.audioclassics.com/modafferi.php3

Bob

Charles,
As I write this, I just finished listening closely to Johann Stamitz
Symphony #2 on station WETA Washington, DC. This station is about 80+
miles from me as I live in SouthCentral Pa. I am using an APS-9 yagi
antenna.

The sound quality is better after the mods, BUT the sound quality
difference is not as great as it was between my TX-930 and the
unmodified MR78 (and the Yamaha is no slouch, it's a very listenable
tuner). Specifically, in the Stamitz symphony I can very clearly hear
the placement of the individual instruments. The harpsichord is right
front and as clear as a bell. I can locate the string bass and the
other strings exist in their own space (as opposed to just a
homogenous paste of strings). Yes, between movements I can hear the
conductor or some instumentalists moving music and the audience
coughing softly. Even at this distance the stereo is fully engaged
and background noise is very low.

As for the Yamaha TX-930, I think it is almost exactly the same as the
TX-950. I have seen the spec sheets for both and they are identical.
The 930 has 24 presets while I believe the 950 has 40. All other
features are identical. Now, I haven't opened up either tuner, but I
would be surprised if component and layout wise they were not very
similiar if not virtually identical. The TX-930 really started my
craze for tuners. I couldn't believe how much better the TX-930
sounded compared to the tuner in my receiver. Tuner sections in even
fairly expensive receivers do seem to be pretty crappy (there's a
technical description). I now listen to my tuner (MR78) more than I
listen to CD's.

Here's a list of the changes Richard did to my MR78:

1. IF tailbiting problem fixed. Ninth and tenth harmonics of 10.7 Mhz
IF frequency 'leak' back into RF input at 96.3 and 107.0 Mhz, causing
slight increase of distortion, noise, at these frequencies.
Modification eliminates this problem.

2. IF regeneration fix - modify grounding in IF chassis, yields
improved weak-signal reception.

3. HF oscillator modification, re-dress connection from L5 to emitter
of Q3 for reduced leakage inductance, improves stability for less
drift, and reduces oscillator pulling on strong signals.

4. Muting ground changed for better muting performance.

5. B- power supply changed to full-wave rectification for less hum
and better regulation.

6. Diode D307 restored to stereo decoder matrix B+ feed, reduces
'plop' noises at fixed output jacks when tuner turned on/off.

7. Prepare chassis and install tiffany gold audio jacks (both fixed
and variable output jacks).

8. Stereo decoder modification to op-amp feedback and stereo matrix
drive circuits for higher slew-rate, reduces distortion, improves
noise immunity, and slightly improves separation.

9. RF tuned circuits modified for higher selectivity, improves
spurious rejection and reduces noise on weak signals when tuner is
used with high-gain antenna systems.

10. IF amplifier filters trimmed for best phase linearity and gain
matching, reduces distortion, slightly improves separation.

11. Jung-Marsh audio capacitor upgrade, eliminates audio distortion
from capacitor dielectric absorbtion.

In addition to above this was done:

Preliminary chassis cleaning and inspection. B- filter capacitor
failing (leaking internal guts and ready to explode!), no other
damage, mechanical or electrical observed. Replaced B- filter
capacitor. Cleaned PC boards. Deoxit-cleaning to switches, controls,
tuning capacitor, internal adjustments. Alignment to RF, IF,
detector, and MPX circuits. Super narrow IF filter not working
correctly. Cut apart filter case with diamond saw, repaired and
re-aligned filter. If alignment finished. Alignment check. Listen
and function check. Computer measurements. Put tuner into RM's audio
system for listen/burn-in/drift test. 10 Hours.

NEW PARTS:
1. NTE323 transistor
2. NTE519 switch diode
3. NTE506 rectifier diode
4. 1.5 Kohm and 8.2 Kohm RCD film resistors
5. 470 mF/100v nichicon elect. capacitor
6. .02 mF ceramic RF bypass capacitor
7. .01 mF ceramic RF bypass capacitor
8. 6 1mF/250v BC film capacitors
9. 10 Kohm RCD film resistor
10. 3.6 Kohm RCD film resistor
11. 4 tiffany gold RCA female jacks
12 ceramic 'gimmick' trim capacitors, as needed, IF amplifier phase
adjust.

Also provided were two pages of performance charts. Audio-classics
provided me with a free original MR78 service manual which Richard had
hand annotated with all the modifications on the schematics. (The
free manual is not normally included but was given to ameliorate some
screw-ups by audio-classics. NOTE: With all said and done I'm am
happy with audio-classics and would give them my business in the
future.)

Bill Corbin

--- In FMtuners@y..., Charles Peterson <charlesp@d...> wrote:

William,

Do you have any impressions of the sonic difference before and after

the update

based on memory? At least such long term memories aren't likely to

the MR78. [.......]

Comparision yami. tx-930 vs tx-950/ I think they are the same
unit. I have seen insides of tx-930 on tunerinfo.com and have seen
inside on my tx-950 , The only real differences are color of pcboard
and the metal cap on front end circuits are different composition.
tx-930 has only 24 presets tx--950 has 40 presets. tx-950 was made
until sometime in 1999. my tx-950 has power supply cap with 8/98 date
code, so its only 7-8 years old.tx-930 was made until 1991.






--- In FMtuners@..., Charles Peterson <charlesp@...>
wrote:

William,

Do you have any impressions of the sonic difference before and after

the update

based on memory? At least such long term memories aren't likely to

be biased by

level differences, assuming you adjust level up and down from time

to time. Do

you believe it improved significantly, and, if so, in what way? I

must confess

that many of my reports are based on such long term memories.

"Rapid switching"

tests, which I find very tedious and confusing, can be equally

subject to error

unless carefully controlled (blind and level matched, for example).

I've now discovered a new far away station I can get at listening

quality even

on my lowly whip antenna, including one station from Houston over

200 miles away

from where I live in San Antonio.

One other amazing thing is how the updated MR 78 can get stereo on

virtually any

signal, even very weak ones.

It's incredible how much audio transparency the updated MR 78 has.

This is very

enjoyable on music. During pre-recorded messages, you can sometimes

hear the

background hum and noise from the tape clearly. There's plenty of

bass response

too, seemingly more than on any other tuner I have; it's got lively

and tuneful

bass which I don't remember hearing on any other tuner through my small
modified LS3/5A speakers.

I wonder how your TX-930 compares with the famous Yamaha TX-950, the

latter

being one of the few tuners to have Sanyo's top MPX chip (LM3450?),

still

considered to be the best today. Even your TX-930 is bound to have

a much later

generation chip-based MPX design than the MR78, so it's surprising

how well the

MR78 does in comparison. I don't have any tuners with

latest-generation MPX

designs. I recently made the mistake of buying a Pioneer TX-950

thinking it was

the Yamaha. It's a cheap early generation digital tuner. At least

I didn't pay

much, only $19.95.

I see that among the things Modafferi *might* do in an update is replace
capacitors with polypropylene units, and "modify stereo decoder for

higher slew

rate..." Do you know what was done more specifically?

Charles

William wrote:

Charles,
I have to agree with your comments about the MR78. [.......]