As I have been working 30 years in Aerospace industry, I am 100% agreed to your point of view. Cripping pins purpose in connectors are used in aircrafts for vibration and less weight. I have been repairing F16 and ground radars for a long time and i can tell you that molex type or similar connectors are only used in pc boards. Spade connectors is a compromise, something in between of them. I think the use of molex is for amateur users only!! All the amps and preamps I have built so far, I have soldered every cable to the boards either in the pcb pad or using space connector."The Wurth/Molex MiniFit connectors specified are an industrial standard and capapble of reliable connections in high vibration environments. I would take them anyday over soldered flying leads due to the reduction of mechanical strain at the solder joint. Industrial/aersopace/automotive applications use connectors not only for convenience but for better protection of the joint from mechanical strain due to the stress risers at the wire/solder joint interface".
Industrial standards are very aware of "economics of manufacture".
I build amplifiers since some 40 years and still prefer solder joints over connectors, but maybe I am an old fashioned stubborn DIY'er. Others are welcome to not agree.
Just something to consider, with Molex connection you have:
1. Molex PCB part soldered to PCB;
2. cable mechanically connected to Molex cable part by crimping;
3. the mechanical (spade) connection.
So three joints instead of just one solder joint.
More can go wrong with the connector isn't it?
An audio amplifier (normally) does not live in a "high vibration environment".
In a well executed solder joint in an amplifier, with well executed wiring, there is no mechanical strain.
There are applications where lead containing solder joints are still used over mechanical connectors; you will find examples in automotive (highly vibrational environment!).
With pads at both sides of the PCB and through hole tinning, you will have a very reliable maintenance free joint (at no extra cost of connectors). My Rotel not even went that far as it's PCB is one-sided copper...
Soldering the cable to the pcb corresponding hole is definately the best way. Spade connector is a compromise.
The idea of that stable and adjustable power supply design has been taken by an elektor old circuit for printers. If many of you are interested in that power supply approach, i will start a new thread.
After reading 2667 posts at this thread, i have come to the conclusion that i will definately build the AN 8R although my 2nd pair of speakers is Cerwin Vega AT100 4R. I am really convinced that the AN team has made an excillent job and we all must be greatful to them.
So i must declare that:
1.It will definately be a dual mono using 2 X 28V / 8A secondaries trafos.
2.Alluminium chassis dimensions will be 460mm D X 400mm W X 200mm H made by my local machinery shop.
3.Heat sinks will be 3 X 160mm D X 40mm W X 200mm H per channel
4. 4 x CRC diyaudio/Firstwatt capacitance pcbs= 2 per channel + and -
5. 2 X 2N2684/87 adjustable power supply pcbs- one per channel.
I must also say that after so many probable modifications and parts replacements that have been discussed here I am a little bit confused.
Can someboby please advise me which circuit diagram is the best for AN construction?? Is there a final one or the one at the post #1 ??
Thank you very much in advance !!!!
So i must declare that:
1.It will definately be a dual mono using 2 X 28V / 8A secondaries trafos.
2.Alluminium chassis dimensions will be 460mm D X 400mm W X 200mm H made by my local machinery shop.
3.Heat sinks will be 3 X 160mm D X 40mm W X 200mm H per channel
4. 4 x CRC diyaudio/Firstwatt capacitance pcbs= 2 per channel + and -
5. 2 X 2N2684/87 adjustable power supply pcbs- one per channel.
I must also say that after so many probable modifications and parts replacements that have been discussed here I am a little bit confused.
Can someboby please advise me which circuit diagram is the best for AN construction?? Is there a final one or the one at the post #1 ??
Thank you very much in advance !!!!
Not sure how you can effectively use so much heat sink area for one channel, and with this amp’s relatively high efficiency, you wouldn’t need to.
40mm heat sinks is what modushop uses, so why go to the trouble of a custom case? I prefer thicker heat sinks, 50-75mm, which also means much less depth is required for the same thermal efficiency. 200mm high sounds fine by me.
I Have purchased those 6 huge heat sinks for a previous design and I have to use them. Think that my 2N6284/87 dual rail power supply board will use them too.
Thank you very much. I always try to find the finest parts for my preamps and amps. I have used many takman,mills and kaddock for my tube preamps. The fine spare parts you are referred to can't be found via mouser of digikey. Any suggestions about decent suppliers??
Then you need to build the AN 4R - as I did. Someone who built the 8R version posted that it really didn't like a 4 ohm load. Whereas my AN 4R is happy to drive 2 ohm loads (Maggie true-ribbons!).
The 4R version likes 22v DC rails - so an 18v secondary transformer.
If you do build the 4R version ... you need larger heatsinks than what I have used - 200 x 300 x 40. (They simply get too hot!
) Or you use fans.
Please remark in my previous post that the 3 X 160mm heat sink depth which is equal to 460mm in total X 200mm Height and 40mm Width. They are more than enough for every project I think. The problem with 8R or 4R construction is the 2nd pair of speakers that is an 8R. So I will not be able to switch to each other. That's the big problem. Another problem is that I use a variable power supply using 2N6284 & 2N6287 for the +- rails and is going to be attached to the same heat sink as the AN amp board. That might increase the thermal condition of the sink.
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I think it might be useful to think about the 4R 8R thing another way. Voltage swing defines the top end of what power you can develop into a given load but it's the current that actually moves the speaker. Those impedance numbers are nominal and the impedance curve of any multiway speaker wanders all over the place, especially near the port and woofer resonance.
I think it's easy to get hung up on the numbers. You will just move the voltage/current balance one way or another with the 8R/4R builds. Most class A amplifiers don't give you the choice of optimising for one nominal load or another, we are spoiled! You really won't be losing much running an 8 ohm nominal speaker on a 4R build. I'd sooner have a little more current capability than a few more watts... that in practice I never use. Build the 4R version and relax 😊
I think it's easy to get hung up on the numbers. You will just move the voltage/current balance one way or another with the 8R/4R builds. Most class A amplifiers don't give you the choice of optimising for one nominal load or another, we are spoiled! You really won't be losing much running an 8 ohm nominal speaker on a 4R build. I'd sooner have a little more current capability than a few more watts... that in practice I never use. Build the 4R version and relax 😊