Bk Monolith-DF

**Ilkka** · **07-16-06, 03:06 PM**

Manufacturer: BK Electronics
Model: Monolith-DF
Provided by: Timosetae
Manufacturer link: Monolith-DF
Price: 736 EUR

Manufacturer specs:
• System Type: 95 Litre reflex tuned to 20Hz, cabinet manufactured from veneered 25mm MDF and Critically braced
• Drive Unit: A 300mm / 12" twin magnet drive unit to increase linear excursion, a cast basket for a solid uncoloured projection of sound without ringing and vented pole piece to help reduce power compression
• Distortion: 5% 102dB @ 20Hz
• Frequency Response: 20Hz (-3 dB) / In Room 15Hz
• Amplifier Input / Output Impedance: High Level 100K - Low Level 10K - Balanced 10K
• Gain Control Range: 80dB
• Drive Unit Impedance: 4 Ohm
• Mains Input: 230V / 50Hz
• Dimensions: 420D X 604H x 540W
• Weight: 46.75kg
• Finishes: Black Ash Veneer, Light Oak Veneer and Cherry Veneer
• True 300W continuous discrete Mosfet amplifier
• 2 Years Warranty
• Truly hand built in Great Britain, when we claim hand built we mean hand built, as there are no SMD components or other automatic placement devices
• Forward Firing 300mm (12")
• Continuously variable frequency control
• Audiophile grade toroidal transformers
• Gas Tight Neutrik connection for long term consistency of sound quality
• Separate controls for high and low-level input adjustment
• Simultaneous connection of high and low level sources
• Balanced Inputs
• Thermal Protection
• Anti Thump
• ASP automatic speaker protection audibly transparent driver protection
• 4 x 16A output devices for effortless current control
• IEC Power Socket
• Doubled flared port for reduced port noise

Configuration as tested:
Phase: 0 degrees
Orientation: Standard down-firing

**Ilkka** · **07-17-06, 10:57 AM**

+/- 3 dB points: 20 Hz - >200 Hz

**Ilkka** · **07-17-06, 10:57 AM**

**Ilkka** · **07-17-06, 03:32 PM**

A gorgeous unit with a top-notch build quality. BK offers both front firing and down-firing versions; we tested the latter this time. The frequency response stays inside the 6 dB window all the way from 19 Hz to over 200 Hz. The crossover works as promised, though the low pass slope is on the shallow side. The shape of the frequency response is one of the best I've seen for a vented sub. The “trick” is that it doesn't have any high pass filtering below its tuning point. That of course can cause some problems when inputting a high level sub-tuning frequency signal. And in fact I did manage to bottom the driver right below 20 Hz at the highest sweep level. With program material you would really have to try to make this happen though. The Monolith offers quite high maximum SPL for a vented 12" subwoofer, especially when considering that it doesn't contain the latest and greatest woofer when it comes to Xmax parameter. The large 4" port stays almost noiseless even at max level. THD stays under 5% for most of the time, but naturally goes sky high below 20 Hz. Group delay stays exceptionally low at all frequencies for a vented sub. Spectral decay shows that there isn't very much ringing. Spectral contamination shows slightly higher than average maximum output capability with much lower than average overall distortion, though it just failed the 100 dB level.

+ Good extension and very good shape of the frequency response for larger rooms
+ Good maximum output capability and low power compression
+ Low distortion
+ Extremely low group delay and short decay time for a ported subwoofer
+ Price

+/- No high pass filter below the tuning frequency
- Not steep enough crossover

**dimmie** · **07-20-06, 01:09 PM**

Can't wait Ilkka

good to see you here.

**russ.will** · **08-18-06, 09:29 PM**

Ilkka,

Anything happening here? Just wondering what your comments are. I know you're a busy boy, but the English language community is awaiting further comment.

Russell

**dimmie** · **08-19-06, 04:13 PM**

Hey russel.

Nice to see you here, how's your new EQ toy working for ya?.

I'm pretty interested to hear about the monolith too, haven't seen illka lately though. Maybe the english community(or at least part of it) hasn't shown enough interrest in his work. And kinda banned him from the AV forums.

Where the are you Illka?

**Ayreonaut** · **08-21-06, 02:00 PM**

The results for this subwoofer are really incredible.

FR: Nice and flat. In a room this would extend into the infrasonics nicely.
LF output: Great with 96 dB at 20 Hz
THD: Very Low above 22 Hz at 110 dB
Impulse Response: Exceedingly tight, as good as the sealed subs.
Decay: Precipitous
Price: 407 GBP which is 770 USD.

This much performance at that price? Is this thing for real Ilkka?

I'm going to find out how much it costs to ship one to the U.S.!

**russ.will** · **08-21-06, 04:37 PM**

Quote:

Ayreonaut wrote:

The results for this subwoofer are really incredible.

FR: Nice and flat. In a room this would extend into the infrasonics nicely.
LF output: Great with 96 dB at 20 Hz
THD: Very Low above 22 Hz at 110 dB
Impulse Response: Exceedingly tight, as good as the sealed subs.
Decay: Precipitous
Price: 407 GBP which is 770 USD.

This much performance at that price? Is this thing for real Ilkka?

I'm going to find out how much it costs to ship one to the U.S.!

It's a big forum (and personal) favourite over here, where it's sold online only. That's how they manage the price.

BK OEM manufacture for a number of other companies including MJ Acoustics and had a hand in manufacture of all of the early RELs dating back to the original Q50. They're no muppets. They design and manufacture all of their own amp panels (110-230v and available separatley for DIY) and their own cabinets (virtually any finish you like and all real wood veneers) but they use off the shelf drivers. In this case the Peerless XLS-12.

It's nearest competitor is the SVS PB-10 which sells for £370 ($700 US). I am guessing for that money you're well into PB-12 Plus territory where I suspect the competition is a little tougher and the obvious advantage it enjoys over here regarding wood veneers evaporates.

Ilkka's results for the Monolith make very interesting reading, especially when you compare it to the SVS 25-31 PC+ in 20Hz tune. Go on, flick back and forth.

I recently heard a friends PB-12 Plus and can assure you, once in a room, the SVS shows a clean pair of heals. But then it should, over here it costs twice as much as the BK. That said, I still can't believe the results I'm getting now it's EQ'd. I get a real big room gain from 25 to 32Hz, with the cuts I've applied at those frequencies, it just never runs out of steam and is effortless at reference levels. This may be helped by the smaller European room.

Russell

**russ.will** · **08-21-06, 04:48 PM**

Quote:

dimmie wrote:

Hey russel.

Nice to see you here, how's your new EQ toy working for ya?.

I'm pretty interested to hear about the monolith too, haven't seen illka lately though. Maybe the english community(or at least part of it) hasn't shown enough interrest in his work. And kinda banned him from the AV forums.

Where the are you Illka?

Hey up Dimmie,

So far the SMS-1 is working just great. It's got a new challenge comming after I made one of the biggest home cinema upgrades I've ever made. We repainted the room a muted mid blue - it was previously a pale cream sort of colour. This of course has had a staggering effect on the picture quality of my projector. None what-so-ever on the sound of course!

The DF has been moved from 1/4 of the way up the side of the room, to the back corner just behind the seating. The SMS-1 is going to have it's work cut out, because this beasty doesn't really need corner placement and I was cutting like a mad thing already. I never could make it work there with the BFD, but that was probably due to lack of patience as I had no way of using REW. With the on screen real time EQ it should be a lot easier, especially through the tricky crossover region. When my new, longer sub cable arrives to replace the previously redundant one I Ebayed 2 weeks ago (Doh!) I'll let you know how it goes and finally post some graphs.

Dunno where Ilkkas gone. Probably on a well deserved break from people flaming him, who don't understand that English is not his mother tongue and therefore that expression can get lost in the translation.

Russell

**Ayreonaut** · **08-21-06, 05:02 PM**

Quote:

Ayreonaut wrote:

I visited the SVS showroom at their Ohio factory last week. I listened to all of their subs from the PB10-NSD to the PB12-Ultra/2. The big ones like the Ultra/2 were literally flapping my pant legs with infrasonic bass. I was impressed, but not overwhelmed. Why, you ask? Time response. Compared to my little sealed 10-incher at home, the big ported 12-inchers are slow and wooly. A look at the Impulse Response and Spectral Decay results above illustrate this very well.

I have discovered that lightning fast timing in a sub is very, very important to me. Wouldn't I prefer a sub that had more LF output than my current 10-incher? Yes, I would. But not at the cost of time definition. But that's simply my preference.

I feared that no affordable sub could deliver great timing and high output at low frequencies, but the BK Mopolith-DF graphed above seems to be able to do it all. I can't wait to set my ears on one.

**dimmie** · **08-22-06, 01:29 PM**

Quote:

This may be helped by the smaller European room.

Yeah I got one of those too.

And it's placed right smack in the corner, and I'm in the corner opposite to that.....

A bfd will probably do some good!!!, as I'm being launched off the sofa whenever something blows up.

Guess U-571 isn't an option pre-bfd.

dimitri

**Manic Miner** · **08-22-06, 04:46 PM**

Quote:

dimmie wrote:

Yeah I got one of those too.

And it's placed right smack in the corner, and I'm in the corner opposite to that.....

A bfd will probably do some good!!!, as I'm being launched off the sofa whenever something blows up.

Guess U-571 isn't an option pre-bfd.

dimitri

If you have excess SPL you can always lower the tune and trade it in for some extra extension. The lower tunes also have a more shallow roll-off starting higher up and therefore the 35-20hz frequency range will be lowered a bit. I use my Plus in 12hz tune for music, and also for every day movie watching. If it's an action blockbuster I use 16hz tune, and if I'm trying to impress someone, 20hz tune.

**Ayreonaut** · **08-23-06, 02:57 PM**

Since you have SPL to spare, try to get the sub out of the corner. If you can position it close to a quarter point away from the end and side wall, the room modes will be so excited and both FR and tansient response will improve. (This is true for rectangular rooms.)

FYI Americans: To have one shipped to Virginia by UPS International Expedited would cost 213 USD.

**dimmie** · **08-23-06, 04:01 PM**

Quote:

Ayreonaut wrote:

Since you have SPL to spare, try to get the sub out of the corner. If you can position it close to a quarter point away from the end and side wall, the room modes will be so excited and both FR and tansient response will improve. (This is true for rectangular rooms.)

FYI Americans: To have one shipped to Virginia by UPS International Expedited would cost 213 USD.

Thanks for your input.

Moving it out of the corner will be difficult for the time being. because I have two little babies and I can't really get in the sweet spot of the room because we need all the space we can get. And we'll be in that corner for some time. I just hope the bfd will make those room modes and boom disappear, or at least make it better. My room is not really rectangular but kinda L-shaped. I'll add some pics.

**Ayreonaut** · **08-23-06, 04:50 PM**

Quote:

Ayreonaut wrote:

...the room modes will be so excited and both FR and transient response will improve...

I meant the room modes will be less excited. Oops!

**russ.will** · **09-14-06, 07:08 PM**

It may, or may not, be of interest, but BK are reknowned for their ability to accomodate requests not listed on their website. The only refusal, so far, was for a piano gloss black lacquer and that may have had something to do with the person asking for it.

Anyway, they have just supplied a passive Monolith DF to a forumite in the UK for £245. That's about $465. To put it in perspective, over here, that's just over half the price of a PB-10 and INCLUDES real wood veneer.

I haven't heard of anywhere they won't ship to.

Just a thought.

Russell

**eddthompson** · **09-14-06, 07:11 PM**

that would be me

(see post in sub forum)

edd

**Ilkka** · **10-11-06, 06:19 PM**

Quote:

russ.will wrote:

Dunno where Ilkkas gone. Probably on a well deserved break from people flaming him, who don't understand that English is not his mother tongue and therefore that expression can get lost in the translation.

Russell

I'm right here Russel.

I've just really busy lately with all the other stuff, so unfortunately I haven't yet posted the comments on the results. But they are definitely coming. I will also post all the results from the previous rounds at the same time, so there will be lots of new stuff to explore soon.

**russ.will** · **10-13-06, 09:54 AM**

Cool.

Russell

**lienly** · **08-07-07, 10:47 AM**

pretty western style home!

Quote:

dimmie wrote:

Thanks for your input.

Moving it out of the corner will be difficult for the time being. because I have two little babies and I can't really get in the sweet spot of the room because we need all the space we can get. And we'll be in that corner for some time. I just hope the bfd will make those room modes and boom disappear, or at least make it better. My room is not really rectangular but kinda L-shaped. I'll add some pics.

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