• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Neumann KH120 Disassembly Pictures

hyperplanar

Active Member
Joined
Jan 31, 2020
Messages
147
Likes
222
Location
Los Angeles
#1
Hi all, it seems pretty hard to find any pictures of the KH120's internals online, so I thought I would post these here. Maybe they can be of use to someone! :)

These pictures aren't of my own KH120s. I found them several years ago with great difficulty thru Google Translate on a registration-only Chinese hi-fi forum. I'll also try to include my interpretation of the original poster's comments on each picture.


The enclosure and main screws holding it all together.
1.jpg


There's a gasket between the two halves of the enclosure, which is covered in an oily sealant substance.
2.jpg


The bass reflex port is well designed, with flared endings, multiple openings to reduce resonances, and plenty of damping material.
3.jpg


Seems like a good amount of care was taken to secure the speaker wires so they don't rattle around.
4.jpg


The tweeter. The magnet is very strong. Titanium diaphragm with fabric (silk?) dampening.
5.jpg


Speaker connections are soldered, so no worries about them coming loose.
6.jpg


Spring washers on the screws.
7.jpg


Woofer. The basket looks like the one on the Peerless SDS series, but (according to the original poster) this woofer's impedance inductance is even lower than the Peerless HDS series.
8.jpg


Woofer side view. According to the OP, it handles +-5mm excursion at 50 Hz without noise.
9.jpg


Rear of PCB. Marked "Sennheiser" on the bottom left corner.
10.jpg


Front of PCB. Lots of dampening and sealant material. Two TDA7293 Class AB chip amps, one for the woofer and one for the tweeter. ST33079 and TL074 op-amps.
11.jpg


Closeup of upper half of PCB. The six blue trim pots on the top are used for the factory calibration of each unit.
12.jpg


Bottom half of PCB. This studio monitor uses an internal SMPS.
13.jpg


Rear half of enclosure, which the TDA7293s are heatsinked to.
14.jpg
 
Last edited:
OP
hyperplanar

hyperplanar

Active Member
Joined
Jan 31, 2020
Messages
147
Likes
222
Location
Los Angeles
Thread Starter #3
Couldn't agree more. Seems like a robust design and the BOM cost was wisely distributed into where it counts.

As a testament to their factory calibration and stability, my pair of KH120s consists of one bought used from Guitar Center of unknown provenance and another is a Sennheiser refurbished unit. Here's how their frequency responses compare in an untreated room sitting on the edge of a desk, measurements taken freehanded about 1.5 feet away on their acoustical axis.
1.png


Needless to say, the stereo imaging and stability amazes me! :)
 

Joachim Herbert

Active Member
Forum Donor
Joined
Jan 20, 2019
Messages
126
Likes
175
Location
Munich, Germany
#5
It is dead silent, though.
 

direstraitsfan98

Addicted to Fun and Learning
Forum Donor
Joined
Oct 1, 2018
Messages
631
Likes
763
#15
Does anyone still use a CRT display? Useless extra magnets on the drivers.....
I do. These will mess up your CRT if you put it anywhere under 2 and a half feet away anyway. Very few speakers are truly magnetically shielded.
 

Similar threads

Top Bottom