I’m new here and my English isn’t very well, but I’ll try my best to make my question as clear as possible.
I’m building a stereo amplifier with two K4004B amplifier kits in mono/bridge mode.
I want to use the K4700 speaker protection kit to protect the speakers against DC and to relay switching the speakers when turning on the power of the amplifier.
But the K4004B user manual states to always first connect the speakers before turning power on when in bridged mode.
The K4700 causes that there is no speaker present when it relays speaker switching on.
I only connected the + of the amplifiers to the PA points of the K4700 and the + to the speakers to the LS points of the K4700, leaving the GND (reversed T) on the K4700 unconnected and connecting the speakers’ - directly to the amplifiers (the other speaker + of the amplifiers, because of the bridge mode).
I thought it would not be very well for the amplifiers to connect both to the GND point of the K4700 when in bridge mode.
Last week I didn’t connect the speakers (stupid mistake) when testing something and both amplifiers died.
I ordered and assembled two new K4004B’s, but I’m not sure if the combination and my way of connecting the kits is the right one.
I hope that this way of connecting the two kits is the right one and that the reason of defect amplifiers is not connecting any speakers at all one time.
If I connected it not the right way, what is the right way to connect this?
Sorry to read you experienced problems.
Anyway, why did you buy 2 new kits. Most likely, it was just a matter of replacing the power-IC’s of the amps.
Frankly, we have no experience with the K4004/K4700 combination.
What DC voltage did you connect to the K4004?
What is the impedance of the speaker?
A picture paints a thousand words. Can you supply a link to a diagram that shows how you hooked up transformer, rectifier, K4004 and K4700, this will allow us to take a look and provide some feedback.
I wanted to order new power IC’s (TDA1514A), but couldn’t find them for a reasonable price.
Since the used K4004B’s were already old (I assembled them in my late teenager years, when I had not much experience) and had experienced some other problems I ordered two new K4004B’s.
The impedance of the speakers is 8 ohms.
I use an Amplimo 78017 2 x 30V/5 A toroidal transformer and a Velleman APS200 power supply module per amplifier kit.
I will make a diagram or a picture of how everything is connected and post it as soon as I made it.
2x30VAC?
Please check the specs of the amp:
Max allowed input voltage is +/- 28VDC.
If you supply 30VAC, the amp will receive +/-42VDC, this will destroy the IC’s.
Here are some pictures, I hope you can see how everything is connected.
If needed, I can make some more (detailed) pictures or a kind of diagram.
As you can see, I use the K8084 pre-ampifier kit and two K4307 LED audio power meters (I had to repair some of the soldering islands for the LED’s when re-positioning them, that’s why you see some yellow wires).
[quote=“VEL417”]2x30VAC?
Please check the specs of the amp:
Max allowed input voltage is +/- 28VDC.
If you supply 30VAC, the amp will receive +/-42VDC, this will destroy the IC’s.[/quote]
Hmz okay, so that’s the problem…
When I bought these transformators and power supply modules, they were recommended with the K4004B’s, the seller said.
What transformator and/or power supply do you recommend?
I hope I can use the same power supply modules.
Power supply modules are OK, transformers not.
These transformers are suited for the (obsolete) K4005.
You can use a transformer that delivers a max. of 20VAC.
20*1.41-1.2= 27V, which is just below the max. allowed input voltage.
[quote=“VEL417”]Power supply modules are OK, transformers not.
These transformers are suited for the (obsolete) K4005.
You can use a transformer that delivers a max. of 20VAC.
20*1.41-1.2= 27V, which is just below the max. allowed input voltage.[/quote]
Okay, thanks for your answers.
I will order some new transformers with a max. of + and - 20 V AC.
So you don’t think that the speaker switch delay destroys the power IC’s?
The voltage issue is far more important and needs to be solved immediately.
To solve the speaker issue, you could add a resistor of say 1K/5W to each relay contact, to make sure that the amp sees a load when the speakers are switched off.
[quote=“VEL417”]The voltage issue is far more important and needs to be solved immediately.
To solve the speaker issue, you could add a resistor of say 1K/5W to each relay contact, to make sure that the amp sees a load when the speakers are switched off.[/quote]
I have changed the transformers to 2 x 18V/4,44A ones and everything works fine.
Is it necessary to add the resistors or will it keep working without them?
