I have the speakers finished. I have completed the assembly of the crossover boards and am now testing the boards as per instructions (using a frequency generator instead of the CD).
After finding a couple of incorrect components and replacing with the correct components I started with the measurements again. My "Part A" measurements seem to be in the right neighborhood. However, I do not obtain stable readings (reading start out slightly high and then decrease to about the proper reading but the values continue to decrease).
I have rechecked all components. All resistors are correct. All other components are correct (and in the correct orientation). I resoldered the joints which appeared iffy.
Any comments or suggestions would be appreciated (other than coughing up the $60 or so and sending to SL)
Thanks
Steve
After finding a couple of incorrect components and replacing with the correct components I started with the measurements again. My "Part A" measurements seem to be in the right neighborhood. However, I do not obtain stable readings (reading start out slightly high and then decrease to about the proper reading but the values continue to decrease).
I have rechecked all components. All resistors are correct. All other components are correct (and in the correct orientation). I resoldered the joints which appeared iffy.
Any comments or suggestions would be appreciated (other than coughing up the $60 or so and sending to SL)
Thanks
Steve
The electrolytic capacitors on the woofer channel output will take a charge and create a DC offset when you're not running into into a reasonable load (I have some RCA plugs with 50K resistors soldered between the connectors - these work fine. When I first ran the tests at some very late/early hour and just clipped on my scope leads, this had me scratching my head for a while).
Otherwise, you might look at your test equipment. For instance, the amplitude of my BK pocket signal generator oscillates a bit when I change frequencies.
As a foot note, the track 2 1545 Hz midrange output is .42V not .40V.
Otherwise, you might look at your test equipment. For instance, the amplitude of my BK pocket signal generator oscillates a bit when I change frequencies.
As a foot note, the track 2 1545 Hz midrange output is .42V not .40V.
An externally hosted image should be here but it was not working when we last tested it.
Hi Drew-
Thanks for the info. I hooked the clips from the frequency generator onto one end of an interconnect (the other end into the board inputs). Where would I put the resistor (sorry, I am a severe newbie to electronics).
Also, I am not completely sure I am making the voltage measurements correctly (not sure what to use as ground when checking voltage at the various outputs).
Can you clue me in here, too?
Thanks again,
Steve
Thanks for the info. I hooked the clips from the frequency generator onto one end of an interconnect (the other end into the board inputs). Where would I put the resistor (sorry, I am a severe newbie to electronics).
Also, I am not completely sure I am making the voltage measurements correctly (not sure what to use as ground when checking voltage at the various outputs).
Can you clue me in here, too?
Thanks again,
Steve
SteveA said:
On the output, between signal and ground. It only matters on the woofer output, and assuming your instrumentation is only measuring AC you won't even notice it.
Any signal ground will work. There's a lot of metal in each RCA jack which makes them convienant.
Do your two channels measure the same (this is where a scope is nice - you can put both channels up or add with one inverted, connect both inputs to the signal generator, and just switch through the frequencies from hight to low)? Making the same mistakes consistantly would be hard, so this might suggest a measurement problem.
When I did mine, I tacked down opposite corners of one socket and forgot about the rest; did the MT1 conections of one channel as a mirror image (oops); and some how became confused and plugged an op-amp in backwards.
Hello Drew-
I found that I had made some rather silly (stupid even) wiring errors. When I corrected them the voltages from Part A were all within acceptable limits except for the Tweeter Output voltage on one channel (courtesy Dave Reite who has helped via email; thanks to Dave also).
So, it would appear I need to check the tweeter section on the right channel board.
I am really eager to hear these things (I have built NC Borealis which are very good; I have built a pair designed by John Krutke using SEAS drivers from the standard line which are very nice sounding considering how inexpensive they are).
Of course, I will have to finish my amp project to complete the system (building two four channel amps)
Steve
I found that I had made some rather silly (stupid even) wiring errors. When I corrected them the voltages from Part A were all within acceptable limits except for the Tweeter Output voltage on one channel (courtesy Dave Reite who has helped via email; thanks to Dave also).
So, it would appear I need to check the tweeter section on the right channel board.
I am really eager to hear these things (I have built NC Borealis which are very good; I have built a pair designed by John Krutke using SEAS drivers from the standard line which are very nice sounding considering how inexpensive they are).
Of course, I will have to finish my amp project to complete the system (building two four channel amps)
Steve
Depending on your initial wiring errors, there's always the possibility that you toasted some ICs when you powered it up. You might try trading the ICs around to different positions and seeing if the problem remains the same.
Hi Catapult-
In fact, that is what I did and found that the offending channel had a bad op amp. I believe the crossover will be functional once I can get a replacement.
People like me appreciate people like you and Drew and Dave (etc) who are willing to help out.
Thanks,
Steve
In fact, that is what I did and found that the offending channel had a bad op amp. I believe the crossover will be functional once I can get a replacement.
People like me appreciate people like you and Drew and Dave (etc) who are willing to help out.
Thanks,
Steve
Davey-
I measured all the voltages per instructions ("part a and b"). I still have ~0.89 V at the woofer output. R64 (on woofer input signal) reads 4.10 V instead of 3.40).
It would appear my problem is localized in that section (p14 of manual, lower right). This, BTW, is on the side which had the bad wiring. The resistors in that section alll measure fine. I have ordered new caps for that section and will replace them (could one or more of these been toasted as well?
With all the additional parts on order I could just as well order another set of pcbs and start on a second set.
Again, THANKS
Steve
I measured all the voltages per instructions ("part a and b"). I still have ~0.89 V at the woofer output. R64 (on woofer input signal) reads 4.10 V instead of 3.40).
It would appear my problem is localized in that section (p14 of manual, lower right). This, BTW, is on the side which had the bad wiring. The resistors in that section alll measure fine. I have ordered new caps for that section and will replace them (could one or more of these been toasted as well?
With all the additional parts on order I could just as well order another set of pcbs and start on a second set.
Again, THANKS
Steve
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