Diary: Constructing a 3 driver open baffle W subwoofer

KS · « **Reply #20 on:** 22 Jun 2008, 09:08 pm »

Is it safe to connect a low dc voltage to the driver wires to visually see the phase...maybe a 1.5 volt dry cell? All the cones must move the same direction when the dc voltage is applied.

rythmik · « **Reply #21 on:** 23 Jun 2008, 12:26 am »

Quote from: KS on 22 Jun 2008, 09:08 pm

Is it safe to connect a low dc voltage to the driver wires to visually see the phase...maybe a 1.5 volt dry cell? All the cones must move the same direction when the dc voltage is applied.

It is ok to use low dc for that purpose. When one sits the woofer up, the left hand is red terminal and right hand is black terminal. That is pretty much the only possibility that the manufacturer can make mistake by inadvertently turning those terminals 180 degrees.

WerTicus · « **Reply #22 on:** 23 Jun 2008, 03:10 am »

I am going to be very embarrassed if i have inverted phase, because i was being very careful to get it correct, and just like traderxfan i initially put the inverted driver out of phase but i was pretty sure that i corrected it.

In any case I still have my mains running full range, however I no longer have a 55hz boost of +3db on them.

Ill try everything suggested and ill double check my phase. And get back

WerTicus · « **Reply #23 on:** 23 Jun 2008, 03:25 am »

Okay im an idiot

Serves me right for trying to finish it off before going to sleep the other night.

I initially wired the VC backwards and the servo correct on the inverted woofer, and then i noticed the VC was backwards and reversed the servo and the VC... so now the vc was correct and the servo was wrong...

Basically the servo is probably working over time right now to compensate for over 100% distortion (according to it)

WerTicus · « **Reply #24 on:** 23 Jun 2008, 03:44 am »

Okay fixed... now its a different beast

Ill do a proper write up after i've had a chance to get the settings just right.

WerTicus · « **Reply #25 on:** 23 Jun 2008, 05:41 am »

must pull self away from sweet spot to write this: AWESOME

Far out its... perfection.

I now have it set to medium damping - 15degrees phase (seems to be the answer ill play some more) - 20hz low pass

also the peq is on with a small boost to 30hz to give the right amount of kick for me.
ive turned off the sources peq its running totally flat and i'm upsampling to 96khz on everything.

rythmik · « **Reply #26 on:** 23 Jun 2008, 12:08 pm »

Quote from: WerTicus on 23 Jun 2008, 05:41 am

must pull self away from sweet spot to write this: AWESOME

Far out its... perfection.

I now have it set to medium damping - 15degrees phase (seems to be the answer ill play some more) - 20hz low pass

also the peq is on with a small boost to 30hz to give the right amount of kick for me.
ive turned off the sources peq its running totally flat and i'm upsampling to 96khz on everything.

I am glad things work out great. It is also good so that we have pretty much come up with all the things requiring attention in adjustment/tuning. One thing that concerns me now is WerTicus has 2 in phase and 1 out of phase, so it essentially ends up with the net of having connected servo for only one driver. If someone connects two out-of-phase and one in-phase, then we end up with a positive sensing coil feedback and that will be very loud oscillation for 3 drivers acting as a panic alarm. Originally I have bought a bunch of 46ohm current limiting resistors. Those are for first-time testing purpose to prevent loud oscillation noise from wiring mistakes. Please put them in series with the amplifier output. After we make sure there is no oscillation, we can then remove this resistor. I would like to listen to recommendation on how this can be done better.

WerTicus · « **Reply #27 on:** 23 Jun 2008, 12:48 pm »

If you make it idiot proof they will just build a better idiot

My mistake occurred because i was doing it at 3am wanting to get it finished when i should have gone to bed.
I also should have triple checked it the next day on my own.

WerTicus · « **Reply #28 on:** 23 Jun 2008, 01:53 pm »

Just about finished... need to attach the cloth properly:

richidoo · « **Reply #29 on:** 23 Jun 2008, 02:30 pm »

Congrats Werticus. Very nice job!! I bet it sounds incredible. Enjoy!

BrunoB · « **Reply #30 on:** 24 Jun 2008, 10:44 am »

I guess your OB sub vibrates a lot when playing hard .
I would put something heavy on top of the sub during the listening sessions, a bag of sand for example.

Just a suggestion,

Bruno

WerTicus · « **Reply #31 on:** 24 Jun 2008, 03:29 pm »

Yes it would probably help, however it does not vibrate that much actually. I have a single metal foot at the back and the front feet offer little movement.

zybar · « **Reply #32 on:** 30 Jun 2008, 01:54 am »

Very cool.

Any measurements?

George

WerTicus · « **Reply #33 on:** 30 Jun 2008, 06:10 am »

No measurments as yet - I might get around to that one day to perfect the tweeking however it sounds very good to me right now.

Im now using low damping and 165^o phase
40hz x over
with 50/24db slope on.

kyrill · « **Reply #34 on:** 30 Jun 2008, 11:03 am »

Congrats WerTicus, great job
already know where you will put the sub in the room?
is there room behind the TV?
it will enhance the output but maybe adjustable?
Must it stand or can the sub lie down?

WerTicus · « **Reply #35 on:** 14 Jul 2008, 05:19 am »

Yeah im just going to leave the sub where it is, there is no other options really behind the TV will screw with the magnet inside.

Open baffle subs do need to be off the wall so its not that simple. You could probably lay it down but i never designed the box to be used like that. (ie, no feet there)

Brian is sending me a new version of the servo so ill do an update when i get that.

WerTicus · « **Reply #36 on:** 4 Aug 2008, 08:12 am »

I got the new servo board in the mail today so ill hook it up shortly and write up some impressions

it will effectively be a blind test because i have no idea what its supposed to do!

Mr Content · « **Reply #37 on:** 4 Aug 2008, 12:41 pm »

Nice Werticus, Hey where in OZ are you, I would like to have a listen if it suits.

Mr C

WerTicus · « **Reply #38 on:** 14 Aug 2008, 09:08 am »

The new servo is ... certainly different, I think the sub is more invisible and better integrated than it was before in general, however its also bottomed out a couple more times than usual but this was on new material so its hard to judge....perhaps i need to adjust the settings again for this servo or this servo is trying to go lower than the last one.

I don't really know what the new servo is supposed to do, perhaps Brian can chime in here. I couldn't honestly say its an obvious improvement just that its different

I need more listening time really.

I 'think' its better....!

Mr Content: I'm sure you can appreciate that I'm not so keen on inviting random people off the internet into my home

Especially members that i have no rapport with who have been a member here for a whole month!

mcgsxr · « **Reply #39 on:** 14 Aug 2008, 10:49 am »

I certainly won't comment on anyone's personal approach to meeting people live that they have only met online (though I will share that 100% of the AC members that I have invited to my home have been exceptional people, and I have valued the opportunity to meet them live) but I can say that I recall Mr Content was here before a month ago, though I think he had a different screen name.

I have read his excellent website numerous times, and am impressed with the body of his work, when it comes to OB.