EQUIPMENT HISTORY:
Everything I am describing below is IMPORTANT, read it please!
This amplifier is part of my "collection" of all things audio, both professional and consumer gear. I personally don't mind a decent NAD piece of gear and actually had three of these 3240PE's, this particular unit was a "to be looked at" as it is NOT WORKING CORRECTLY - see the FULL details below.
These 3240PE amplifiers surprise many. They use an amplifier design which NAD called Power Envelope Technology and this design results in an amplifier that easily produces far greater audio output than the listener could be expecting.
This amplifier is designed to supply 40W Audio power (RMS) per channel into a "normal" 8 Ohm loudspeaker system but on loud passages/peaks, this amplifier easily delivers 80W output on each channel - the idea being that when listening to music with a wide (demanding) dynamic range, this amplifier will sound great no matter if the audio is of a low level or suddenly jumps up in level considerably, the 3240PE takes it all in its stride. Other amplifiers, when pushed hard, will spit the dummy and sound absolutely horrible (distortion).
Actually reference to the NAD technical information shows these amplifiers can produce up to 160W per channel (for short periods - similar to Peak Power) if called for.
I have over the years collected together a LOT of quality audio equipment due to my business activities in pro audio post production and general electronics but the day has finally arrived!
Well, my wife says "for goodness sake, get rid of that mountain of gear" so them's my orders ... out they all go.
This equipment does have issues, and it is extremely important that the complete description is read in full.
THE CONDITION OF THIS EQUIPMENT IS CLEARLY STATED BELOW, BOTH COSMETICALLY AND ELECTRICALLY
There is no warranty, there are no returns - but I am very thorough and do not "gloss over" any issues I might discover!
Even if the new owner doesn't feel up to repairing or having this equipment repaired, it's is still a great source of some very hard to find parts.
NAD 3240PE Stereo Amplifier
Model: 3240PE
Made in Taiwan
Serial # D324025772
Released to market 1988~1989
Frequency response: 20Hz ~ 20Khz
Power Output (8 or 4 Ohm) 40W RMS per channel
+6 dB of dynamic headroom is available, which means the 3240PE is capable of delivering over 160 watts per channel (8 ohms)
THD (at full power): 0.03%
Damping Factor: 50
Signal/Noise Ratio: Phono 76dB Aux 102dB
Inputs provided:
Phono
Tuner
CD
Tape
Dual speaker outputs (A & B)
Speaker impedance switch: 8 Ohm or 4 Ohm
FRONT PANEL:
Speaker select: A,B,OFF or A+B
Bass
Treble
Bass EQ (ON or OFF)
Mono (ON or OFF)
Tape Monitor (ON or OFF)
Input select switch
Loudness (ON or OFF)
Volume & Balance (Concentric control)
LED's indicate POWER ON & SOFT CLIPPING
Dimensions: 410 x 100 x 350mm
Weight: 7Kg (packed weight closer to 8Kg)
COSMETIC CONDITION:
First glance, not bad at all in fact it is in pretty good condition, cosmetically.
Front panel is clean, all lettering (silk screen) is undamaged and perfectly readable.
Knobs are all present and clean
Side panels are clean with only the very lightest of scratching, none of which breaks through the outer coating
Top panel is clean, with only a couple of very light marks - not scratched.
NO signs of a "drop" in other words, no bent case or frame.
One speaker terminal/binding has the plastic top section missing! You can still use this terminal though, or just use the speaker outputs B
NO case screws are missing.
All feet are present
Base panel is fine, no rust observed (I have seen this before, rust underneath indicates it has been in a flood or suffered previous water damage - serious problems!) This unit has not seen water!.
Next I take a look inside ...
The first thing I noticed is the large empty area inside! Strange this one, this model never had a tuner or other boards built in and referring to the Service manual, it shows a tuner board but there is no way this unit has ever had a tuner fitted, the front panel isn't designed for one!
Overall, the assembly of components on the PCB is a bit "sloppy" with components leaning this way and that, so from a construction/engineering point of view it's been hand assembled with pretty "ordinary" QC control.
I get the impression that "cost cutting" had raised it's ugly head once again - these were all hand assembled and being made in Taiwan, I feel the assembly standards had "sagged"
HERE IS THE PROBLEM - Shoddy workmanship in the past!
Next I noticed the power output "strip" WHAT A MESS! Someone (prior to me obtaining the amplifier) had been servicing this amplifier and done a pretty messy job with the thermal grease around the output stage transistors, in fact I would even say this has been undertaken very poorly.
This happened quite a while ago because the white grease has gone very hard.
Then I noticed one channel power output devices has been changed, two output transistors have been changed from the original 2SB187/2SD1047 pair to a pair of 2SD1718/2SB1163. I have no idea why the repair person did this, the original devices are still readily available (around A$6 ~ A$10 pair)
Then I also noticed a couple of suspicious looking resistors, they have suffered heat damage which has made their markings disappear!
The heatsink fans on one side (where the transistors have been substituted) is a different colour, looks like this end of the heatsink got hot at one time!
These things are not good signs and definitely point to issues in the power amplifier stage of the amplifier - more about this further down in the description!
All capacitors, including the filter capacitors look fine. The large electrolytics are 2x 6800uF 80V & 2x 6800uF 50V (all are Nippon Chemical)
Open frame trimmer pots are used (not good either)
I then looked underneath to see what sort of job the repair person did with the desoldering-soldering. Fortunately a lot better than the application of thermal grease top side! No broken or burned tracks, solder joints look to be fairly well done.
Extensive fusing with six holders all in a row! NO fuses are "blown"
TESTING:
Yeah, this is what everyone wants to know! What does it sound like?
I ran the tests described below with the covers off, I want to see if anything strange is happening (e.g smoke!) or strange smells!
This amplifier has the preamplifier and power amplifier linked via a U link on each channel, nice and easy to split the audio system for testing.
I used a separate NAD 7150 as my test power amplifier when checking the preamp.
I have checked both the line level inputs (CD,Tuner) and the much more sensitive Phono input (with my test turntable)
HERE WE GO...
Plugged it in, on comes the Green front panel LED - all good.
You won't hear that reassuring "click" from a protection relay, there isn't one! The protection system is totally electronic and silent.
PRE-AMPLFIER TESTING
Bass, Treble, Volume and Balance all working fine - WITHOUT OPERATING NOISE (scratching or intermittent channel loss)
Sonic switches (Bass EQ, Infra On Off, Mono, Low Level & Loudness) all functioning fine - no noise when activated.
Four input selector works fine, NO issues with noise or one channel dropping out (common issue)
Audio has been run through all inputs although I focused a lot on the phono input as I am playing a lot of vinyl at the moment.
No issues at all, nice clean audio using the phono and line level inputs.
PHONO NOTE: I also run my own NAD 7150 and in comparison with this 3240PE, the phono audio quality on this amplifier is acceptable but not as good as the 7150. The 7150 uses a special plug in card and all active devices are discrete whereas this 3240PE phono section is op amp based, using the JRC 2043D which is similar to a 4558, not a very spectacular op amp.
POWER AMPLIFIER:
Linked the preamp to the power amplifier and had a good listen ...
BOTH CHANNELS ARE SHOT!
This will be a repair/restore/re-adjust bias settings for sure...
CHANNEL A does have a low level output and reasonable quality but it doesn't sound "right"
CHANNEL B is like a dodo bird, dead as. No audio of any kind on this channel.
I checked both outputs for the dreaded DC voltage being present, none at all thank goodness! Never should you see DC voltages at your amplifier speaker outputs because if you connect your prized speakers to such an amplifier, your speaker voice coils suddenly turn into little heaters and then go POOF! This is something you must prevent at all costs - ALWAYS check an unknown amplifier for DC at the speaker outputs before connecting your speakers.
SUMMARY:
So here we have a 3240PE with a good preamplifier but the PA needs a good restoration job.
Schematics are available online (free) but those I found are a bit shonky and difficult to read, they do help but make the repair process a bit slower as you try to decipher what the schematic says!
Two sets of those original power transistors, a few 1/4W resistors (nothing special), change the trimpots for sealed types and if you felt like it, recap at least the filter electrolytics (check the ripple current to see how well they are filtering the AC from the rectifiers.
My intention was always to do a "restore job" on this amplifier but it never happened! I have now been pushed along by my wife (quite sensibly) as she is tired of seeing all this gear just lying around waiting for me to do something with it! I could have spent more time looking closely at the output section but haven't, I have a lot of gear to work through and my time allowance on this 3240PE has now run out ... hopefully someone else can have fun with this one!
It just needs a bit of tender loving care from a capable professional technician, not a ham fisted person that seems to have been playing around inside here previously - it really isn't a very good repair job they have done.
Please don't forget, that when shipping via my website (this one) I will ship FREE because it meets the conditions for shipping at no cost - this applies to anyone in Australia
The free shipping is automatically applied in the checkout area of this website
