SpeakerTalk

willem-57 · Posted: Sun Jul 27, 2014 6:30 pm Post subject:

But my sound of the 105.4 is very good, i have the impression that the T33 is very open and beautiful. I know the sound of the high and mid because i had in the past the CS7 kit, who has the same B110 and T33.

willem-57 · Posted: Mon Jul 28, 2014 8:01 am Post subject:

willem-57 · Posted: Mon Jul 28, 2014 6:42 pm Post subject:

When i removed the burned resistor, underneath was to read: R3
I got an answer today: Willem, hi, KEF have very kindly supplied us a schematic and layout drawing. R3 is 15 ohms.

Good that we first asked Kef. Shocked

By the way, what does that piece of network, it has to do with the tweeter, but what exactly Question

willem-57 · Posted: Tue Jul 29, 2014 9:46 am Post subject:

I think i found the 15 ohm resistor that i need, including datasheet: http://uk.farnell.com/welwyn/w22-15r-ji/resistor-ww-7w-5-15r/dp/9504575

audiolabtower · VIP Contributor 500+ Joined: 06 Jan 2009 Posts: 686

audiolabtower · VIP Contributor 500+ Joined: 06 Jan 2009 Posts: 686

willem-57 · Posted: Tue Jul 29, 2014 6:53 pm Post subject:

Yes, i think you can be right, but in the Kef lay out of the SP1129 crossover R3 is 15 ohm's ..... Rolling Eyes

Another question: what happends with a resistor that has been overheated, does it in- or decrease in value, or does nothing chance?

audiolabtower · VIP Contributor 500+ Joined: 06 Jan 2009 Posts: 686

These are wirewound, so unless they fail open circuit they would not drift much, I have seen burnt ones in eg valve guitar amps that were still in spec. The look of them after 35 years is not even that strange, they can go white powdery just from atmospheric oxidation. What is strange is the heat spot on the board - that is wrong. If you were replacing them in an amp I would advise to solder them in a couple of cm off the board, so air is all around for dissipation. But on a speaker board that should not be necessary since you would assume that Kef rated them well within the design voltage input of the drive unit, even under continuous use.

willem-57 · Posted: Tue Jul 29, 2014 8:38 pm Post subject:

There was some white powder that i brushed away, before i photografed them. When i solder them new, i will give them a little more space around so that they can cool better.

By the way, Jerry from Falcon also advised to give them space from the board.

willem-57 · Posted: Tue Jul 29, 2014 9:36 pm Post subject:

Ok, i'm ready to order, there is a difference, the 150V are not made anymore, that will be now 100V, and the capacitators will be matched pairs.

C1 - 120 MFD 150v become 100 v
C2 - 120 MFD 150v become 100
C3 - 120 MFD 150v become 100
C4 - 120 MFD 150v become 100
C5 - 72 MFD 150v become 100
C6 - 30 MFD 150v become 100
C7 – 7.0 MFD 50v LowLoss
C8 - 50 MFD 50v
C9 - 12 MFD 150v become 100
C10 – 3.3 MFD 50v LowLoss
C11 – 4.2 MFD 50v LowLoss
C12 – 4.2 MFD 50v LowLoss

R3 15R0/5/W22

speakerguru · Posted: Tue Jul 29, 2014 9:48 pm Post subject:

willem-57 · Posted: Tue Jul 29, 2014 10:25 pm Post subject:

Good idea, i shall also try to give R3 more space by putting C9 as far down as possible, making the space between C9 and C12 bigger.

Is there a problem that the 150v type's becoming 100v types Question

speakerguru · Posted: Wed Jul 30, 2014 7:43 am Post subject:

willem-57 · Posted: Wed Jul 30, 2014 8:03 am Post subject:

I got an 20 year old Accuphase E405, 2 x 170W RMS 8ohm load, 2 x 250W RMS 4 ohm load, 2 x 350w RMS 2 ohm's load. http://www.accuphase.com/cat/e-405en.pdf

I never play very loud.

willem-57 · Posted: Wed Jul 30, 2014 8:52 am Post subject:

By the way, found a topic of another guy who has recapped his 105.4 crossover with Alcap, he is very pleased with it. If you look carrefully you can see that his crossover is a little different than mine, mine has 4 x 120MDF ( C1-2-3-4) He has 3 x 120 MDF and 1 x 80 MDF, another SP number, i think Question

http://www.audiokarma.org/forums/showthread.php?t=576854