Big thanks to the gurus here. I have converted my speakers too. Wanted to save the wood work and cost, the back plate and the heat sink were reused. The amp was separated and taken off. The rest of small holes are sealed by foam. I got cheap crossovers which x/o point is around 2k-3k, tested by connecting only the woofer and playing the 20-20kHz sound. There are jumpers for tuning. Looking at the backside of it, it appears like of the jumper adds another 155J100 capacitor to the HF path in parallel. This cap is 1.5uF. I think I have to open the speaker again to connect this jumper to make it close to the recommendation above. The other jumper bypass the green thing (cap? resistor?) in the LF path. At least it has a x/o point is close to target, rather than those 4kHz I saw.
Too many people around the global need this conversion mates.
Too many people around the global need this conversion mates.
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I think so. I tested it is the power board of the left speaker not passing electricity to the transformer, so I believe the rest parts are good.
I am new to this forum. Does it have a message feature so we can chat so not to hijacking this post?
Kai, I have posted to the Swap Meet section. Hopefully I will be allowed to PM soon.
Gentlemen, my apologies for the off topic discussion.
blach, how does the back board look like at the end? I saw you have tools and space to work on it.
I recommend you ditch those cheap crossovers. They contain a woeful little iron core inductor which will do nothing to enhance the sound.
Better to build your own crossovers using quality components, including air core inductors, as described in the thread. That won't cost the earth.
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Gentlemen, it’s me again.
While I am sourcing the parts to make my own crossover, I came across some online calculators. The problem is, when inputting 3 or 4 ohm as impedance and 2500Hz as the x/o frequency, the result is quite different from the recommended values above.
Is it because the impedance of Q100 is 8ohm whilst the X300A is 4ohm? Did I do the calculation wrong?
Thanks for your time.
While I am sourcing the parts to make my own crossover, I came across some online calculators. The problem is, when inputting 3 or 4 ohm as impedance and 2500Hz as the x/o frequency, the result is quite different from the recommended values above.
Is it because the impedance of Q100 is 8ohm whilst the X300A is 4ohm? Did I do the calculation wrong?
Thanks for your time.
It is because the online calculators do not take into account the impedance that each of the drivers actually has at the frequency of crossover.
Remember that impedance is not a fixed quantity, but varies with frequency, and values like 8 ohm and 4 ohm are only nominal (or average) values. It is the impedance of each driver at the crossover frequency which is important in crossover design, and you don't have access to those figures.
Others have attested that the Q100 crossover works well in this situation, and I would stick with it.
Remember that impedance is not a fixed quantity, but varies with frequency, and values like 8 ohm and 4 ohm are only nominal (or average) values. It is the impedance of each driver at the crossover frequency which is important in crossover design, and you don't have access to those figures.
Others have attested that the Q100 crossover works well in this situation, and I would stick with it.
Hi,
Like many others I too have a set of dead x300a speakers. Looking at the schematic, I wanted to make sure that the HPF was supposed to be wired 180 out of phase from the lpf. The diagram indicates the tone generator going through the filter connected to the ground terminal of the tweeter and the positive terminal of the tweeter connected to ground. If someone can just sanity check me, that would be helpful. I believe my Thiel’s which also have a first order crossover do the same thing as there is some phase inversion characteristic to first order cross overs (If I remember correctly). This is not an area of expertise for me obviously, so any feedback would be welcome.
Also, I got some Kaudyn Q4 caps for this. I believe these are non-polarized. Is that correct as well.
Thanks as always for the helpful feedback. The DIY audio community is an amazing resource.
Jumping in the bandwagon but I just got a pair of second hand x300a which died after less than two weeks and many, many quirks (right speaker working intermittently, mini-jack not working but WiFi OK, balance working weirdly) -- sound was awesome when they were working, though!
I'm a bit out of luck as I can't find a pair KEF Q100 crossover anywhere (there is 1 on Ebay), and I only have very basic notions of electronics (but I can solder!). I've read all the messages here, and based on RunningCookie the solution is likely to DIY the board.
From the above message, here's what I think I need:
1. Capacitor: Solen 3.9uF 400V
2. Resistor: Mundorf 0.68ohm (someone mentioned 5W ceramic)
3. Inductor: Solen 0.68mH 20AWG (someone recommended 0.68 lower resistance)
4. Terminal plates: any favourite?
5. PCB, green connectors, wires: recommendations?
Brownie points if you know a place that sells worldwide, as I'm in NZ and sourcing stuff can be challenging.
Thanks!
The required crossover could hardly be much simpler and the component values and schematic are clearly shown in post #116.
The type of terminal plate is relatively unimportant. If you choose one of a decent size, the components could be hard wired to the rear of the terminals thus obviating the need for a PCB. Hot glue can be used to secure the components to the rear of the terminal plate.
Happy soldering!
The type of terminal plate is relatively unimportant. If you choose one of a decent size, the components could be hard wired to the rear of the terminals thus obviating the need for a PCB. Hot glue can be used to secure the components to the rear of the terminal plate.
Happy soldering!