The solder found in the store is very well received, said to be one of the finest solders.
Kester is very good too, although I'm not sure if this one is the exact product that was recommended by 6L6 (look here)...
I followed his recommendation before the store had the FIRE METALL EUTECTIC SOLDER, so I got myself 2 spools of cardas' eutectic solder. This is indeed very very nice stuff for a good build. (Be cautious though with their solder-flux. It's very good too, but will leave your boards extremely dirty, and cleaning a fully populated board can be a nasty job...)
Concerning heat... they can take quite some (and then).
Up to a certain limit, it is better to go high temperature (~300°C?), because the part and solder-lug heat up very quick, and the solder-connection perfectly flows into its place in a few seconds. Heat up both the part and the lug with the solder-tip carrying a bit of solder (helps transferring temperature), and melt the solder on the part. Watch it flow into the lug while still heating. Remove the iron and watch the solder flow into the connection. (from the moment the part is melting the solder, this lasts about 0.5").
Then, there's parts which are especially prone to overheating: this with a blasting case, and active stuff like LEDs, diodes, etc. ...
And: The required temperature (or better: thermal energy) depends very much the on circuit: If your soldering a part onto a fat copper-trace like a ground-thing or something, all the heat is being just sucked away like nothing, whereas on a fine little signal-circuit... woosh-a-blubb!
Kester is very good too, although I'm not sure if this one is the exact product that was recommended by 6L6 (look here)...
I followed his recommendation before the store had the FIRE METALL EUTECTIC SOLDER, so I got myself 2 spools of cardas' eutectic solder. This is indeed very very nice stuff for a good build. (Be cautious though with their solder-flux. It's very good too, but will leave your boards extremely dirty, and cleaning a fully populated board can be a nasty job...)
Concerning heat... they can take quite some (and then).
Up to a certain limit, it is better to go high temperature (~300°C?), because the part and solder-lug heat up very quick, and the solder-connection perfectly flows into its place in a few seconds. Heat up both the part and the lug with the solder-tip carrying a bit of solder (helps transferring temperature), and melt the solder on the part. Watch it flow into the lug while still heating. Remove the iron and watch the solder flow into the connection. (from the moment the part is melting the solder, this lasts about 0.5").
Then, there's parts which are especially prone to overheating: this with a blasting case, and active stuff like LEDs, diodes, etc. ...
And: The required temperature (or better: thermal energy) depends very much the on circuit: If your soldering a part onto a fat copper-trace like a ground-thing or something, all the heat is being just sucked away like nothing, whereas on a fine little signal-circuit... woosh-a-blubb!
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I used the Cardas Quad Eutectic Solder on my ACA. Flowed fine and I didn't have any issues at all.
Cardas Solder
Cardas Solder
I've used that specific Kester (in various diameters) in the link and also the Fire Metall.
Both exceptional solders, IMO, and you can't go wrong with either.
Note the diameter of each for your preference and application.
IMO, with either of those solders, for most applications, you will not need to add additional flux. I generally only add a bit if I need to reflow a joint or (gasp) remove a mis-stuffed part.
The DIYAudioStore solder is an absolute dream to work with. It has a somewhat lower melting point than most other high end solders, it flows smoothly and evenly, and the flux is very easily cleaned off with alcohol on q-tips after the joint is complete. It produces exquisite mirror-finish joints every time. Get a spool and you’ll be able to produce picture perfect joints every time. Enjoy!
As a total newbie, can you explain what the large Q1/Q2 MOSFET's are doing...different things? As in, I scared the cr@p out of myself when I did the bias and saw 24 volts (I was connected to the wrong one of the two, but thought either I cooked it or I did something wrong during the build). Why is one getting 24V at the center pin, and the other 12V? I would have assumed they were being used symmetrically and receiving the same voltage. Thanks!
center pin? that would be the drain pin....and yes, one of them will have 24 volts and the other 12 volts as how it should be.....assuming your psu is 24 volts...
You are kidding, right?? The output stage is very, very similar, and for the purposes of answering his question, the zen series, particularly 1, is certainly a great place to start.
Minimum transformer VA for ACA build?
I have had a pair of the early ACA monoblocks run by two 24 Volt computer supplies for about 5 years now and really love them. Soon after building the first ACA, I purchased a single stereo chassis and a spare ACA kit to go into it. I bought the chassis with the intention of powering the amp in it with a pair laptop supplies. At this point I would rather install a linear power supply, but the chassis is very small and space is limited.
I have a pair of Plitron 25 Volt toroidal transformers rated at 127 VA handy. Unfortunately, it is too tight to put both of them and all the other power supply parts into the chassis.
I have a few questions please...
What is the minimum amount of VA required of the transformer for the most recent version of the ACA?
If it is workable with one of these transformers for both channels of the ACA, would it be better to just use the laptop bricks rather than a linear supply made with a single 127 VA transformer? I will be using the DIY Universal Power Supply PCB.
I have had a pair of the early ACA monoblocks run by two 24 Volt computer supplies for about 5 years now and really love them. Soon after building the first ACA, I purchased a single stereo chassis and a spare ACA kit to go into it. I bought the chassis with the intention of powering the amp in it with a pair laptop supplies. At this point I would rather install a linear power supply, but the chassis is very small and space is limited.
I have a pair of Plitron 25 Volt toroidal transformers rated at 127 VA handy. Unfortunately, it is too tight to put both of them and all the other power supply parts into the chassis.
I have a few questions please...
What is the minimum amount of VA required of the transformer for the most recent version of the ACA?
If it is workable with one of these transformers for both channels of the ACA, would it be better to just use the laptop bricks rather than a linear supply made with a single 127 VA transformer? I will be using the DIY Universal Power Supply PCB.
If you have a read through you will find each ACA consumes approximately 1.5 Amps, therefore 3 Amps as a pair. So at 24 volts that's 72 Watts of power consumption (or heat dissipation) 24 x 3.0 = 72. For your question 72 watts equates to 72 VA.
BUT a 25 volt AC transformer will get you 35 volts DC after rectification and smoothing...
That will be too much for some of the components on the standard ACA, some are only rated at 25 volts DC.
If you want to go down the linear supply route choose an 18 volt AC transformer with a minimum 100 VA, more VA is better.
BUT a 25 volt AC transformer will get you 35 volts DC after rectification and smoothing...
That will be too much for some of the components on the standard ACA, some are only rated at 25 volts DC.
If you want to go down the linear supply route choose an 18 volt AC transformer with a minimum 100 VA, more VA is better.
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Don't forget that the VA rating is an AC quantity, just multiplying the DC current draw and voltage is a DC power quantity. 72 watts in the load isn't really the same as saying you need a 72VA transformer. This is hugely important with the ACA because the load current is continuous, its not a like a Class AB amp that might only draw its max current for a short time period.
A transformer winding would typically be rated for around 1.8 to 2 times the current draw of the DC rail to ensure a safe working limit for the transformer. So a 3 Amp current draw at 24 volts DC would need a 5.4A 18 volt winding as an absolute minimum (97VA).
The SMPS is definitely the best solution imo for this amp. Small, lightweight, efficient and cool running, no mains related noise components... what's not to like
A transformer winding would typically be rated for around 1.8 to 2 times the current draw of the DC rail to ensure a safe working limit for the transformer. So a 3 Amp current draw at 24 volts DC would need a 5.4A 18 volt winding as an absolute minimum (97VA).
The SMPS is definitely the best solution imo for this amp. Small, lightweight, efficient and cool running, no mains related noise components... what's not to like