@felix1024 thanks for sharing your speaker protection schematic! I found it in the thread a couple of days ago and have started teaching myself kicad to make use of it! 🙂 I appreciate everything you uploaded.
Ok, I already have the diyaudio 5U chassis. I now understand that it is pre-drilled for a TO3p package. If I want to minimize drilling/tapping, couldn't I just purchase NJW3281/1302 transistors which are TO3p? I'm using 4 pair. Wouldn't that mean I would just have to drill/tap for one of the pairs.....or won't it fit due to the length of the pcb?
Thanks,
John
Thanks,
John
5U what length. There are mounting holes and the driver holes that also need drilled. What is your intended rail voltage?
Hi Andy,
My plan was to have approximately 71 V rails, but I haven't bought any parts yet. The chassis is the standard diyaudio 5U.
John
My plan was to have approximately 71 V rails, but I haven't bought any parts yet. The chassis is the standard diyaudio 5U.
John
Depending on your speaker load and power supply design, the NJW3281/1302 could be outside their SOA.
Then let me ask the question another way. On Sheet 2 of the BOM are there any transistor choices for a 4 pair 71 volt rail that will minimize drilling/tapping that won't put the devices outside their SOA?
PSU I am planning will be dual mono 500VA toroidal transformers (linear supply). Speaker load will be a nominal 4 ohms.
John
PSU I am planning will be dual mono 500VA toroidal transformers (linear supply). Speaker load will be a nominal 4 ohms.
John
It's the weekend again, so I can get back to this.
I have only managed to test the main EF3-4 board in isolation.
The LED issue is still present without the IPS board, which narrows things down for now.
Some recommendations from this week (Thank You!):
Checked fuses - fine
Between TP3 & TP4 - Measure close to rail voltage
Other
Replaced Q103 & Q104
Replaced Q105 & Q106
Rechecked Resistors
Replaced all BAV21 & 1N4148
I have only managed to test the main EF3-4 board in isolation.
The LED issue is still present without the IPS board, which narrows things down for now.
Some recommendations from this week (Thank You!):
Checked fuses - fine
Between TP3 & TP4 - Measure close to rail voltage
Other
Replaced Q103 & Q104
Replaced Q105 & Q106
Rechecked Resistors
Replaced all BAV21 & 1N4148
Yes, RN means military standard so it will survive higher power loading than CMF of the same rating code.
Both boards were behaving in the same way. D108 does not light.
On Board 1
As an experiment, I switched back to the Red Leds from the BOM: LTL42NKRKNN
Both LEDS worked; a standard red LED and the LTL42NKRKNN
On Board 2
I reassembled the second board using both LTL42NKRKNN. Only one LED works.
On Board 1
As an experiment, I switched back to the Red Leds from the BOM: LTL42NKRKNN
Both LEDS worked; a standard red LED and the LTL42NKRKNN
On Board 2
I reassembled the second board using both LTL42NKRKNN. Only one LED works.
- Voltage to ground after RLED2 to GND is around -28V
- Voltage to rail between RLED2 and D108 is 1V
- On D109, which lights, after RLED1 Voltage to Ground is around 1.6V
- Voltage to rail between RLED1 and D109 is 28V
- Both RLED resistors check out, and the LED orientation is correct.
I'm almost done with my first IPS board. What a build. Never had more confidence that I'm putting the right part in the right place [though still lots of opportunities to mess it up].
I will be driving Magnepan speakers with 4 ohm loads. I am using the 10K for the input impedance. I've searched but not yet found any guidance on using a 6.8uF vs. a 10uF cap for C1. I'd appreciate any comments or direction.
Thanks
I will be driving Magnepan speakers with 4 ohm loads. I am using the 10K for the input impedance. I've searched but not yet found any guidance on using a 6.8uF vs. a 10uF cap for C1. I'd appreciate any comments or direction.
Thanks
I have another question for the Wolverine Design Team. I am having difficulty interpreting the rail fuse ratings on the chart on Sheet 2 of the BOM.
I will be using two 500 VA transformers with dual 50 V secondaries to support approximately 71 Volt rails to drive a 4 ohm load. My read of the chart is to look at the 1000 VA transformer with 71 Volt rails. The chart says to halve the VA rating if you are using a separate transformer for each channel. That sends me back to the 500 VA transformer which indicates a fuse between 4A and 10A. That's a pretty wide current range. Exactly what size fuse do I use?
Am I interpreting this correctly?
Any help would be appreciated,
John
I will be using two 500 VA transformers with dual 50 V secondaries to support approximately 71 Volt rails to drive a 4 ohm load. My read of the chart is to look at the 1000 VA transformer with 71 Volt rails. The chart says to halve the VA rating if you are using a separate transformer for each channel. That sends me back to the 500 VA transformer which indicates a fuse between 4A and 10A. That's a pretty wide current range. Exactly what size fuse do I use?
Am I interpreting this correctly?
Any help would be appreciated,
John
One approach would be to buy a bunch of fuses from 4A to 10A. Start with the smallest and see what you can get away with without nuisance blowing.
Transformer has a 500VA rating.
At each secondary the theoretical maximum continuous AC current is 0.5 x 500/50 = 5Aac
After rectification and filtering multiply the AC rating by 1.414 for the maximum continuous DC rating. However the peak DC current able to be supplied by your smoothing capacitors is almost unlimited. So, to protect your speakers choose 4A and to protect remaining transistors, if any, choose up to 10A.
At each primary the maximum continuous current (for me with 250Vac mains) is 500/250 = 2Aac. Without AC inrush current limiting on your transformers the initial current into the transformer may blow the 2A AC fuse.
Johno, you wrote "So, to protect your speakers choose 4A and to protect remaining transistors, if any, choose up to 10A."
Yes, mains here are a nominal 120 volts AC. I don't understand how this works in practice. There are two fuses (one for the + and one for the minus rails) on each channel. They should be the same value, correct? If so, should they be 4A or 10A? If the amplifier is working correctly, what is highest current draw it will typically see?
Thanks,
John
Yes, mains here are a nominal 120 volts AC. I don't understand how this works in practice. There are two fuses (one for the + and one for the minus rails) on each channel. They should be the same value, correct? If so, should they be 4A or 10A? If the amplifier is working correctly, what is highest current draw it will typically see?
Thanks,
John
not 100% the same as your build, I have a single 800VA transformer, but running amp boards at +/-72Vdc (so close).
I have a 8A on the ICE mains (with a softstart) and I started with 4A and one blew from an unrelated transistor failure, but when I looked at the other channel, I could see the filament had been hot and was no longer silver and perfectly straight, more dark grey and had a slight bend in it.
I replaced all four fuses with 6.3A (I had that on hand, otherwise I would just go with 6A) and have been running it for almost a year now without any issue.
I have a 8A on the ICE mains (with a softstart) and I started with 4A and one blew from an unrelated transistor failure, but when I looked at the other channel, I could see the filament had been hot and was no longer silver and perfectly straight, more dark grey and had a slight bend in it.
I replaced all four fuses with 6.3A (I had that on hand, otherwise I would just go with 6A) and have been running it for almost a year now without any issue.