Hi Ant, hope you're feeling better!
OK, that looks fairly straightforward, you will just have to remove the link between the phono and the pcb above it, and insert your LT circuit in the gap. As for grounding, have a look over the board and see if you can find any evidence of a start grounding point, it may be on the pcb or a possibly on the chassis. You also need to see if you can find the +- supplies for the ICs, either trace back from the power pins of one IC on the board, or look for the voltage regulator chips.
OK, that looks fairly straightforward, you will just have to remove the link between the phono and the pcb above it, and insert your LT circuit in the gap. As for grounding, have a look over the board and see if you can find any evidence of a start grounding point, it may be on the pcb or a possibly on the chassis. You also need to see if you can find the +- supplies for the ICs, either trace back from the power pins of one IC on the board, or look for the voltage regulator chips.
OBI.....hurry up and finish man! your mouth will DROP at the sound of this sub.
I just finished mine, and BOY, no words to describe it!
I just finished mine, and BOY, no words to describe it!
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An externally hosted image should be here but it was not working when we last tested it.
pinkmouse said:
Thanks for the advice Al.
I've been having trouble with my chest infection again, really has put me on my backside. Its a horrible feeling not being able to breath properly. The antibiotics gave a temporary repreave but I'm on a stonger dose now and I'm off into hospital tommorow for a chest x-ray
All of this means that I've pretty much put on hold everything including work and hobbies. Hopefully things start looking up in the near future.
pinkmouse said:No rush!
Get well soon.
Cheers Al
Feeling much better today. Went to the 'ospital and I found out that I'd got fluid on the lungs. I'm 27 years old and I've got stuff that people twice my age have never had. I've been told to stop smoking, rest up and keep taking the meds.
It makes me wonder about the whole MDF dust thing since I've been really exposing myself to it over the last couple of years, don't get me wrong, I do wear a mask but there's also other nasty gases that are released when you cut this stuff up such as formaldehyde. Althought its said that these are in such tiny trace amounts that it shouldn't be able to harm a mouse let alone a man.
Eitherway, I'm somewhat puzzled as to how its come about and I've been told its probably from a combination of smoking, the cold weather, a bad cold prior to this and being generally run down.
Nevermind anyway, I'm just glad I ain't got lung cancer or something crazy like that.
Getting past all this depressing talk lets move on to something more fun.
I've been taking another look at the BK amp this evening and I'm confused as to where the +/-12v is coming for the opamps in the preamp section. Maybe you could take a look Al:
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An externally hosted image should be here but it was not working when we last tested it.
I'm assuming the voltage regulators are the IC bolted to the small black heatsinks and its these that step down the initial voltage and current to something more to the liking of the opamps. However the LT circuit I'm wanting to insert into the signal path requires a 12-0-12 and the wire that's coming out from roughly where the stepdown bit is only has two wires.
There is another comming from the amp to preamp section that has 3 wires but its looks like its on the input section.
Sorry for the poor explaination but I'm somewhat confused myself. I do have a multimeter and I guess the best way to find out is to start testing for voltages.
If I do however find out that I've only got +12v and ground then where will I find the -12v? Or should that be where will I find the ground if I've got +/-12v?
pinkmouse said:That grey wire looks like screened signal cable to me. On the basis of pure logic, I'd have a look at that 3 core white ribbon cable.
Oh, and the chest is probably just the fags, I'm only just getting over the bad flu I had six weeks ago... :where's the smoking smilie when you need it?:
Thanks, I'm being dumb. There's no mono signal that needs 3 wires is there?
If I disconnected that ribbon cable and tested the voltages, is there any chance that something could be damaged from the preamp section not being powered up?
And the fags really are a filthy habbit. Trying to stop is tough though when you actually enjoy it
ShinOBIWAN said:
Well - balanced line...
Unless you short something, pretty unlikely. You could check for continuity for the earth with no applied power, and once you've found that, use a crocodlie clip to attach the black probe of your meter to the main earth star, then with the power on, you only need to worry about one probe. That way, you might be able to get away with testing without unsoldering anything.
Nice work again Ant, hope you get better soon, but give up that dirty habit!
We looked at using the BK module for our sub, but in the end made our own complete plate amp with LT and everything, measuring just 12"x12" www.8ballaudio.com
If you need any help with the LT or measuring the driver etc just give me a shout, I have written a good guide on measuring T/S parameters.
We looked at using the BK module for our sub, but in the end made our own complete plate amp with LT and everything, measuring just 12"x12"
www.8ballaudio.comIf you need any help with the LT or measuring the driver etc just give me a shout, I have written a good guide on measuring T/S parameters.
Al
I'm confused
I took voltage reading and the 2 core wire had 5v - isn't that a bit much for a low level signal?
The 3 core looks to be the correct one but I measure 16-17v. How do I figure out which is ground BTW? I did measure around 33v when I was messing around switching between the connections.
Also, the large ceramic resistors that you can see in the pics on the last page get extremely hot. This is safe I presume?
I'm confused
I took voltage reading and the 2 core wire had 5v - isn't that a bit much for a low level signal?
The 3 core looks to be the correct one but I measure 16-17v. How do I figure out which is ground BTW? I did measure around 33v when I was messing around switching between the connections.
Also, the large ceramic resistors that you can see in the pics on the last page get extremely hot. This is safe I presume?
richie00boy said:Nice work again Ant, hope you get better soon, but give up that dirty habit!
We looked at using the BK module for our sub, but in the end made our own complete plate amp with LT and everything, measuring just 12"x12"
If you need any help with the LT or measuring the driver etc just give me a shout, I have written a good guide on measuring T/S parameters.
Hi Rich
The lowball looks nice, good work on that.
This TS guide you've written; is it any easier or more accurate than a moderately well calibrated Speakerworkshop setup? This is what I use at the minute but would be interested to take a look at another way. Please send me the details to:
zeroex_15 at hotmail . com
David Gatti said:Nice work Shin. I never knew you were a closet bass nut
I know too much is never enough, but are you sure these aren't overkill ?
I would have thought 1 sub would have been enough. Corner placed, a single one could probably reach 115dB at 20Hz!!
I think everyone is a bass nut at heart.
I don't really listen at 100dB much let alone 115dB, what I'm aiming for is a natural extension to develop the Perceives into a 3.5way almost or rather a limited bandwidth 3-way with subs. The Perceives will happily reach down to 40hz but after this there's very little in the way of bass. This is where the AV15's will take over for stereo listening and offer stereo bass of course. They will be connected via highlevel for this.
For movies I'll just use both on the LFE channel via low level.
The BK amps are quite flexible and offer level controls for each input.
I think the main advantage of 2 subs is stereo bass for music and reduced distortion.
ShinOBIWAN said:
Depends, if the amp module has a DC blocking cap, they may just have omitted any DC blocking on the crossover. Do you have access to a 'scope?
With your meter set to DC, put the black probe on one pin, then the red probe on each of the others in turn. Hopefully you got it right first time, and you should measure -16V and +16V. If not, move the black probe to the next pin and repeat until you do.
Yup, that's why they're big and ceramic!
pinkmouse said:
No scope.
I'm using BB OPA2134 in the LT, isn't 17v a bit much for for one of these?
Thanks for the ground tip.
Yup, that's why they're big and ceramic!
That's good then, always freaks me out when you smell that heat discharge from new components and boy do those resistor get very hot. I actually think its a bad design because the resistor are flush up to the PCB instead of stand off a couple of mm to allow air to circulate and there's also various caps in physical contact with them and these also got hot.
I would have spaced them out a little more but its all guaranteed and should it fail then BK are said to have very good after sales.
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