A Warning on Speaker Relays
Some may have spotted the Amplimo speaker relays in pictures I shared with my previous posts #1200 and #1217. For those who consider speaker relays as well a word of warning, please do not interpret this as an implicit recommendation for this type of relays. In our case the Amplimo speaker relays showed severe reliability issues after a very short time ( < 1 Month) of operation. When the second failed we kicked all of them out and replaced them by wire bridges. Actually, IMHO there is no need for speaker relays but if somebody feels better with it let me strongly recommend to consider just ordinary industrial relays. They are (have to be to stay in business) highly reliable, we had them running in the proto II (post #723) for years without any issues. So don´t trade reliablity that comes with ordinary relays against non-evidenced performance advantages of fancy stuff.
Markus
Some may have spotted the Amplimo speaker relays in pictures I shared with my previous posts #1200 and #1217. For those who consider speaker relays as well a word of warning, please do not interpret this as an implicit recommendation for this type of relays. In our case the Amplimo speaker relays showed severe reliability issues after a very short time ( < 1 Month) of operation. When the second failed we kicked all of them out and replaced them by wire bridges. Actually, IMHO there is no need for speaker relays but if somebody feels better with it let me strongly recommend to consider just ordinary industrial relays. They are (have to be to stay in business) highly reliable, we had them running in the proto II (post #723) for years without any issues. So don´t trade reliablity that comes with ordinary relays against non-evidenced performance advantages of fancy stuff.
Markus
Recently I replaced original FQA parts to Toshiba K1530 / J201 In standard F5 and felt much more details and lowered fatigue when listening to high levels.
Big thanks Patrick for this recommendation and not only this...
Toshiba Fets are bigger In size and require better handling when mount to heatsink. What do you think - can be risky to redrill mounting hole to 4 mm to get better pressure using 4 mm bolt
Big thanks Patrick for this recommendation and not only this...
Toshiba Fets are bigger In size and require better handling when mount to heatsink. What do you think - can be risky to redrill mounting hole to 4 mm to get better pressure using 4 mm bolt
Patrick,
in the GB thready you wrote about solder:
"Make sure you take time to go through them before starting to orderor solder".
I have a bunch of 3-components and 4-components eutectic solder. I was planning to use the 4 one, with lead, as it wets better and lower the temperature of the tip. Do you have different suggestions ?
I have already a F5turbo running in my office, which I`m pleased, so I`ll take some time to accumulate the parts.
Thanks
Stefano
in the GB thready you wrote about solder:
"Make sure you take time to go through them before starting to orderor solder".
I have a bunch of 3-components and 4-components eutectic solder. I was planning to use the 4 one, with lead, as it wets better and lower the temperature of the tip. Do you have different suggestions ?
I have already a F5turbo running in my office, which I`m pleased, so I`ll take some time to accumulate the parts.
Thanks
Stefano
I meant you should take time to read the information before you start ordering parts or soldering PCBs.
As to the actual solder I use, in the EU we are environmentally responsible and do not use leaded solder as much as we can avoid.
So I use German made Sn95Ag4Cu1 which melts at 220°C.
And I use Oki Metcal PS-900 with 420°C tips.
You will find normal soldering iron set at 320°C for leaded solder to struggle with lead-free ones containing 4% silver.
Patrick
As to the actual solder I use, in the EU we are environmentally responsible and do not use leaded solder as much as we can avoid.
So I use German made Sn95Ag4Cu1 which melts at 220°C.
And I use Oki Metcal PS-900 with 420°C tips.
You will find normal soldering iron set at 320°C for leaded solder to struggle with lead-free ones containing 4% silver.
Patrick
Well, unless there is a reflow process and several different stages of soldering (with different alloys) - which is not the case of hand soldering - I strongly suggest to pick the eutectic composition which has congruent melting, and solidifies homogeneously. Hypo or hyper eutectic compositions have coexisting liquid and solids which can cause hot cracking of the joints or components shifting (critical for small SMD devices), or for devices which have a lot of temperature variation. Lowering the temperature also helps reducing the chance of embrittlement of the pads.
With respect to environmental concerns, lead is an issue for mass production, not for 10-20 pieces of DIY amplifiers. The solder used in a F5X would have very little Pb inside. Much less than what is lost in a recycled car battery (lead gets melted and recycled but the juice is not, so you can really recycle only 97-98% of the lead used). There are much worse chemicals going in landfill, Mercury, arsenic (from LED), thallium, and so on. And guess what ? In 2018, 2% of the world electricity was used in data centers. At this rate of growth, in a couple of decades Facebook and company will generate more CO2 than the whole flight industry.
I will stick to the 4 eutectic ! Long life and prosper !
Stefano
With respect to environmental concerns, lead is an issue for mass production, not for 10-20 pieces of DIY amplifiers. The solder used in a F5X would have very little Pb inside. Much less than what is lost in a recycled car battery (lead gets melted and recycled but the juice is not, so you can really recycle only 97-98% of the lead used). There are much worse chemicals going in landfill, Mercury, arsenic (from LED), thallium, and so on. And guess what ? In 2018, 2% of the world electricity was used in data centers. At this rate of growth, in a couple of decades Facebook and company will generate more CO2 than the whole flight industry.
I will stick to the 4 eutectic ! Long life and prosper !
Stefano
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I bought almost a full kit including a full chassis still unassembled. As I realised that I would be a total pain to too many people I sold it to someone with more experience than I have. That said I must comment that the standard of boards and chassis are the best I have seen. But when a group-buy is dead/over/finished we cannot expect to have the originators at our beck and call several years after the event.
Lastly, it is utterly unfair to designers who go to any real lengths to debug their designs to attempt to recreate that design as almost without exception such builders tend to 'have a better idea' substitute component values etc etc and end up with a far from perfect amp, thereby causing confusion and worst of all DOWNGRADE THE REPUTATION OF THE ORIGINATOR.
Thank you for defending us.
It is amazing that people in the first world accuse copies of intellectual properties from the developing countires, and rightly so.
And yet they will not hesistate to do so themselves as a hobby.
The worst is that it is done without even understanding how things work.
And we have evidence that such copies were sold to other people, fully finished.
Apart from missing the fun for DIY, buying a fully finished forgery is not what this place is about.
I cannot help wondering why this place is now full of such threads, where it is only about forgeries bought on ebay.
Patrick
It is amazing that people in the first world accuse copies of intellectual properties from the developing countires, and rightly so.
And yet they will not hesistate to do so themselves as a hobby.
The worst is that it is done without even understanding how things work.
And we have evidence that such copies were sold to other people, fully finished.
Apart from missing the fun for DIY, buying a fully finished forgery is not what this place is about.
I cannot help wondering why this place is now full of such threads, where it is only about forgeries bought on ebay.
Patrick
I got the new GB boards. They are amazing. Thanks to EUVL and the other folks for all the work they are putting to give a few of us the pleasure to DIY good singing amplifiers. The intellectual pleasure is about building these objects, slowly and perfectly, not in the quick excitation of owning a fake copy. It is not about money. It is about the pleasure of building something great and EUVL has done (and keeps doing) a remarkable job.
As it is a rather long time since the first prototypes were made, even some of the passive components have now become obsolete.
For example, the 105°C electrolytic main capacitors from Panasonic are no longer produced.
A possible substitute is Nichicon LGY series (also 105°C, long life).
In addition, we have moved from PRP resistors to Vishay Dale in the last few years.
It is because of reliability problems of the former experienced in our DAO HPA project.
You can replace 0.5W PRP by Dale RN55, and PRP 1W by Dale RN65 or RN70.
If you find some more such items, please raise it here and I'll make sure there is an alternative.
Merry Christmas,
Patrick
For example, the 105°C electrolytic main capacitors from Panasonic are no longer produced.
A possible substitute is Nichicon LGY series (also 105°C, long life).
In addition, we have moved from PRP resistors to Vishay Dale in the last few years.
It is because of reliability problems of the former experienced in our DAO HPA project.
You can replace 0.5W PRP by Dale RN55, and PRP 1W by Dale RN65 or RN70.
If you find some more such items, please raise it here and I'll make sure there is an alternative.
Merry Christmas,
Patrick
For the new comers, make sure you match your MOSFET source resistors using a 1.25A constant current source.
This you can build using a LT1085 on a large heatsink, running on 4V supply.
You will also need a low tempco current sensing resistor, such as Isabellehütte PBH.
And a stable and accurate DMM for measuring the voltage drop (with the 4-wire methiod).
If you cannot get MPC74's, let us know.
We still have plenty, even matched ones.
Patrick
This you can build using a LT1085 on a large heatsink, running on 4V supply.
You will also need a low tempco current sensing resistor, such as Isabellehütte PBH.
And a stable and accurate DMM for measuring the voltage drop (with the 4-wire methiod).
If you cannot get MPC74's, let us know.
We still have plenty, even matched ones.
Patrick
If you have MOSFETs matched to < 10mV, at least you want the same matching for the source resistors.
And then you can check how accurate your current source and voltmeter has to be to meet that accuracy.
Sending you resistors is work for us.
Plus that you miss part of the building experience.
So we'll only do that if you cannot source the MPCs (in some countries).
Alternative is Riedon PF2203 0R2 at Digikey.
They are already at 1%, which corresponds to 4mV at 2A bias.
Thin film and low tempco.
Will fit PCB. But you get what you pay for.
Patrick
And then you can check how accurate your current source and voltmeter has to be to meet that accuracy.
Sending you resistors is work for us.
Plus that you miss part of the building experience.
So we'll only do that if you cannot source the MPCs (in some countries).
Alternative is Riedon PF2203 0R2 at Digikey.
They are already at 1%, which corresponds to 4mV at 2A bias.
Thin film and low tempco.
Will fit PCB. But you get what you pay for.
Patrick