things that puzzle me in the night..

AlfieDring wrote: 4D wrote: is it better to run 2 x 8 ohm drivers linked in parallel of an amp in bridge mode or one driver on each channel in dual channel mode Did you mean 2 *8ohm in series for 16ohm bridge operation of the amp? that would be equivilant to one driver/side at 8ohm except everything would be tied together.... i cant say what the right answer is there. Id be tempted to go for bridging into 16ohm if the drivers share a horn/airload and 8ohm/side one per channel if there in seperate boxes with a distance between them? That way you'd avoid a possible compound or simply not noticed failure if one driver (or amp channel) in the "common airload" cabinet failed. In the seperate boxes/channels situation, and if your lucky enough to have the DSP to spare, you can have a go at playing with differential delays to direct the bottom end :) 4D wrote: Now as a inline 10 db pad producer, what is your take does it effect the integrity of the signal or just cut the level.  ? I would have thought the pad itself (electrically no different from a fader on a desk but set to one position?) would only drop the level, however this will mean your signal/noise ratio over the cable run after the pad will take a hit equal to the level drop. Hope that makes sense, stonking hangover today

In this particular instance I was referring to two c-audio sr707's driving two F218's loaded with 300w 8ohm oem pd186's .  The choices link the drivers in in parallel to give 4ohms or individually to give 8 ohms and use the the 707 in bridge 2250w at 4 ohm, or dual mode 435w 8 ohm per channel.

service dept Steve wrote: Now then. Bridge mode. if you have a perfect amplifier (which doesn't exist); ie 100w at 8R, 200w at 4R, 400w at 2R etc you could hook it up like this: 2 x 8 ohm drivers linked in parallel in bridge (4R) or one driver per side (8R x 2) Your perfect amp would give 2 x 100w into each driver with one on each side (200w in total) but in bridge it would provide 400w into the 4R load so this is only really an impedance question. Now,if you had 2 ohm speakers....

you seem to have that wrong.

An amp that does:
100W 8R, 200W 4R, 400W2R  in stereo will do  in bridge:  400W into 8R bridge or 800W into 4R bridge

Remeber that in bridge, each half of the amp sees half of the impedance ... so as far as each side of the amp knows its just driving a 2R load,  so for 4R bridge just take the 2R stereo figures and add them together.  if you are ever looking at specs and the that calculation doesn't work out, then it means either the laws of physics have just stopped working, or they were lying about one of the figures.

Driving...

Manic dj's via an ff4000 (another dj mixer with a fearsome output level)

So 8ohm dual on full chat with the limiters on brick or 4ohm bridge load with the gains knocked back and some room to breathe.

In testing the clip lights seemed to come on at the same level in either mode..

For some reason I'm trying to persuade myself it sounds plumper at 8ohm.

4d, Once again the answers in the question, although we all know that the quick way to kill speakers is to feed them with distortion...
The good old sr707 had one major flaw and that was that the clip lights didn't work properly. They show clip only when they are at full brightness which is pretty hard to tell usually, The input was reasonably accurate though, it does want 775mv for full output if that helps.

service dept Steve wrote: cilla.scope wrote: hehe,  always a bad idea to post whilst the room is still spinning ..  they day they make a laptop with a breathalyzer ....  That will be the weekend then.. I think I should go to the pub before I say something else silly.

Yep I'm off to my daughters for sunday lunch..


Slangevar...

4D, I thought I'd better keep my head down yesterday afternoon after, what shall we call it, "lunch", anyway all better now.
I will be doing another eBay assembly run this week, more testers, pad-in-xlrs etc and would love to sell you some pads BUT an alarm bell is ringing, You said "Manic dj's via an ff4000 (another dj mixer with a fearsome output level)" if you were hoping to control a mixer running into the red this is not the way, distortion is a speaker killer as you know so you would need to check that the dj mixer is still clean even way into the red before you can pad it down, if not or if you're not sure you will need to use phono pads that the HIFI boys use on the inputs from the cd players ( which will raise the s/n ratio) or cover the master fader in tape as it seems the standard limiting method
Anyway, let me know if you need anything making up.
Steve