In this review, we will be comparing S400 and R-51M, two Passive Bookshelf speakers from Buchardt and Klipsch. Let's have a brief look at the main features
of Buchardt S400 and Klipsch R-51M first before getting into our more
detailed comparison.
What size room are the Buchardt S400 and Klipsch R-51M speakers good for?
The size of the room in which you are planning to use these loudspeakers is an important decision factor. Here we have compared their suitability to various sizes of environments considering their size and max power parameters:
In the following sections, we will get into more detail in order to better understand how the Buchardt S400 and Klipsch R-51M compare and hopefully end up with enough arguments to decide which one of these loudspeakers is the better choice for you.
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Drivers
Both S400 and R-51M are 2-way speakers.
| Driver |
Buchardt S400 |
Klipsch R-51M |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
0.74-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 6-inch
|
1 x 5.25-inch
|
S400 features a 0.74" Custom fine weave soft fabric textile aluminum waveguide Tweeter and 1 x 6" paper Woofer with a Crossover frequency at 2000Hz. On the other hand, the R-51M features a 1" Tractrix Horn Tweeter and 1 x 5.25" Copper-spun IMG Woofer with a Crossover frequency at 1660Hz.
Frequency Response
S400 has a frequency range of 33-40 kHz whereas R-51M has a frequency range of 62-21k Hz. With a minimum frequency of 33Hz, the S400 can go significantly deeper on the low side and provide stronger bass compared to the R-51M's min frequency of 62Hz.
Below graphs depict how these two speakers compare with the max, min and average values of the Min and Max Frequencies of other speakers in the Bookshelf class in our database.
Low Frequency
Bookshelf Speakers
High Frequency
Bookshelf Speakers
None of these speakers achieves full range experience which is commonly agreed as 20Hz-20kHz. In order to achieve lower lows / deeper bass, we recommend you pair these with a subwoofer. Visit our Powered Subwoofers section to find out more about the available options.
Impedance and Sensitivity
S400 is a 4 ohms speaker compared to the R-51M which has a nominal impedance of 8 ohms. Lower impedance speakers, especially the ones that are rated at 4 ohms may put more pressure on the amplifier unit especially when played at high volume levels, so make sure the amp you pair with the S400 can provide this impedance level.
These two speakers also have different sensitivity levels. S400 sensitivity is rated at 88 dB and the R-51M's is rated at 93 dB. This 5 dB difference makes the Klipsch R-51M a more sensitive speaker compared to Buchardt S400, hence will play louder with the same amount of watts.
Sensitivity
Bookshelf Speakers
Power Range
Power
range is the range of input power in watts RMS that a loudspeaker is designed to handle. While using an amplifier within this range ensures the nominal performance , inputting a power that is higher than the max wattage can result in a damaged speaker.
S400 can handle a max power of 200 watts RMS from the amp the whereas R-51M has a max power handling value of 85 watts RMS, 115 watts less than the S400.
Keep in mind that a higher max power handling value doesn't necessarily make that a louder speaker
compared to a lower max handling speaker. Loudness or the sound level is also impacted by parameters
such as Impedance, sensitivity and system efficiencies.
Physical Specs
Size of a speaker can sometimes become an important decision factor due to space constraints or in some cases purely for esthetic reasons. In this section, we are going to compare Buchardt S400's and Klipsch R-51M's external dimensions. Buchardt S400 has external dimensions of 375 x 180 x 245mm ( 14.75 x 7 x 9.6inch) whereas Klipsch R-51M has external dimensions of 338.0 x 178.0 x 215.0mm ( 13.3 x 7.0 x 8.4inch) .
Buchardt S400 is clearly the larger of the two speakers. Its body is 2mm wider, 37mm taller and 30mm deeper than Klipsch R-51M.
Below you can see the front view size comparison of Buchardt S400 and Klipsch R-51M in scale.
Comparison image of Buchardt S400 and Klipsch R-51M Size and External Dimensions
Base Surface Area Comparison
Base surface area of a loudspeaker may become a determining factor when the space in your room or desk is limited.
The base surface area of the Buchardt S400 is approximately 441.0cm2 / 68.4inch2 and base area of the Klipsch R-51M is approximately 382.7cm2 / 59.3inch2. The S400 requires 15% more surface area than the R-51M which gives it a small disadvantage on placement in tight spaces.
Here is an another comparison that shows both speakers on a BDI Octave Media Cabinet, next to a standard size amplifier and turntable in scale:
Size Comparison image of Buchardt S400 and Klipsch R-51M on a Media Console
Weight Comparison The weight of a loudspeaker can become an important factor if you need to move and reposition the unit often. Weight of a speaker can also "sometimes" be an indicator of the rigidity of the enclosure and the quality of the internal components used. The Buchardt S400 weighs 7.30kg / 16.1lbs and the Klipsch R-51M weighs 5.00kg / 11lbs. This makes the S400 46% heavier than the R-51M.
Here is a comparison of how S400 and R-51M's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of Klipsch R-51M?
Here are the items that come with the R-51M:
2 Bookshelf loudspeakers 2 Grilles (installed) 8 Self-adhesive rubber feet Quick Setup Guide Important Safety Instructions Warranty Information
 Max Input Power |
200 watts
vs
85 watts
|
Handle more power from your amplifier |
 Woofer Size |
6 inches
vs
5.25 inches
|
Larger woofer |
| Low Frequency Response |
33 Hz
vs
62 Hz
|
Generates deeper bass |
 High Frequency Response |
40k Hz
vs
21k Hz
|
Generates higher frequency |
 Passive Radiator |
one 5x8-inch
vs
None
|
Increases the bass performance |
 Sensitivity |
93 dB
vs
88 dB
|
Play louder with same amount of amplification power |
 Nominal Impedance |
8 ohms
vs
4 ohms
|
Less selective with amplifiers |
 Height |
338mm
vs
375mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
382cm2 (178x215mm)
vs
441cm2 (180x245mm)
|
Takes less floor space |
| General |
Buchardt S400 |
Klipsch Reference R-51M |
| Brand |
Buchardt |
Klipsch |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
40-200 watts |
Up to 85 watts |
| Sensitivity |
88 dB |
93 dB |
| Impedance |
4 ohms |
8 ohms |
| Frequency Response |
33-40 kHz |
62-21k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
6" |
5.25" |
| Woofer Composition |
paper |
Copper-spun IMG |
| Woofer Surround Material |
n/a |
Rubber |
| Tweeter Size |
0.74" |
1" |
| Tweeter Type |
aluminum waveguide |
Tractrix Horn |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
2000Hz |
1660Hz |
| Firing Direction |
n/a |
rear |
Physical Specs |
|
|
| Height |
375.0mm (14.8") |
338.0mm (13.3") |
| Width |
180.0mm (7.1") |
178.0mm (7") |
| Depth |
245.0mm (9.6") |
215.0mm (8.5") |
| Weight |
7.30kg (16.1lbs) |
5.00kg (11lbs) |
| Enclosure |
Passive Radiator |
Bass Reflex |
| Finish |
n/a |
MDF/Wood-grain vinyl |
| Available Colors |
Black, White, Walnut,Graphite Oak |
Black |
| Mounting Bracket |
No |
No |
| Recommended Stand Height |
n/a |
24-28" |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
n/a |
No |
Other |
|
|
| Parts Warranty |
|
5 Years |
| Labor Warranty |
|
5 Years |