Magnat Betasub 38 A

[Ilkka]

Manufacturer: Magnat
Model: Betasub 38 A
Provided by: Marek Sound
Manufacturer link: Magnat Audio Produkte GmbH - Home und Car Hifi - Lautsprecher, Subwoofer, Verstärker
Price: 599 EUR

Manufacturer specs:
Principle: Active 15" bassreflex subwoofer, downfire system
Size: (W x H x D) 420x615x520 mm
Lower cut-off frequency: 18 Hz
Upper cut-off frequency: 200 Hz
Magnetically shielded: no
Power output RMS: 200 Watt
Max. power output: 400 Watt
Cut-off frequency, low: 50 Hz
Cut-off frequency, high: 200 Hz
Power ON/OFF switch
Specials Down-fire construction
Aerodynamic optimized “Air flex” port
High-power long-throw woofer
Real-time Limiter (r t-limiter)
Active SPL equalisation (LPC)
Compact and slim MDF-cabinet
Level- and crossover- frequency adjustment
Phase switchable 0°-180°
High-level input
Low-level input
Automatic standby circuit
Switchable mains voltage 115/230 V

Configuration as tested:
Phase: 0 degrees
Orientation: Standard down-firing, port facing the mic

[Ilkka]

+/- 3 dB points: 25 Hz - 200 Hz

[Ilkka]

[Ilkka]

Magnat's enclosure was incredibly light for its size. It features a 15" driver, a ~3" port and a 200 W (RMS) amp. The driver is pointing towards the ground/floor. There isn't a bypass switch for crossover, but the frequency response stays rather flat past 100 Hz, although a port resonance can be seen at ~150 Hz. The slope of the low pass filter is pretty gentle, which can be heard as an excessive mid bass bloom. Extension could be better, though 25 Hz is still rather well. Maximum output in upper bass range is closing in 110 dB, but there is a lot of output compression in 25-50 Hz range. Same problem can be seen in the THD graph; the THD grows intolerably high in that range. Especially when it consists from 3rd and 5th order harmonics. But unless one goes above 100 dB, overall distortion stays really low. Group delay stays low enough, and there is only little ringing at low and mid bass frequencies. Spectral contamination stays lower than average, though the 100 dB level shows a lot of distortion. A pretty good price/performance ratio unless one needs extreme extension and really high output levels.

+ Good shape of the frequency response for smaller rooms
+ High and clean upper bass maximum output capability

- Somewhat weak extension
- High mid bass output/power compression
- Somewhat light enclosure which can be prone to “walking”, and rattling against the floor

i have listen to this sub for a cuple of months now and i like what i am hearing,but i live in an apartment with naibors and so, so i havent push it to its maximum levels really...
quite nice attac&depth for me anyway!

[Blaser]

The cabinet is IMO small for a 15" sub, hence less output below 30 Hz compared to some other subs tested be Illka. The tune seems to be something around 23 Hz, could you confirm this Illka?

Thanks for the time and efforts made for all these measurements!

Blaser

[Ilkka]

blaser wrote:

The cabinet is IMO small for a 15" sub, hence less output below 30 Hz compared to some other subs tested be Illka. The tune seems to be something around 23 Hz, could you confirm this Illka?

Thanks for the time and efforts made for all these measurements!

Blaser

The tuning frequency seems to be around 32 Hz. That's where the major (port) compression occurs.

Larger enclosure and lower tune could definitely improve its low frequency performance. It would also need a larger port (or multiples).

[Blaser]

I find the results quite confusing. In the beginning I thought about 32 Hz(compression curves), but when looking at the THD curves, normally the driver movement is minimal at tuning and so normally less THD occurs (this is why I doubted the tuning could be 23 Hz)....

Can you pls explain why this happens? Your valuable input (as always will be very much appreciated)

Blaser

[Ilkka]

blaser wrote:

I find the results quite confusing. In the beginning I thought about 32 Hz(compression curves), but when looking at the THD curves, normally the driver movement is minimal at tuning and so normally less THD occurs (this is why I doubted the tuning could be 23 Hz)....

Can you pls explain why this happens? Your valuable input (as always will be very much appreciated)

Blaser

There is also a possibility that the tuning frequency is ~23 Hz but there is a HP filter at ~30 Hz. The THD graph supports this hypothesis.

Although if you look at all the vented subs I've measured, the major compression always occurs at the tuning frequency. On the other hand the THD graphs aren't as constant.

So I'm still standing behind my original statement. Of course it's impossible to prove it without taking some extra measurements.

Anyways, thank you for bringing this up. Don't be afraid to make another question.