FROM--jameshillj
"To me, adding a dc protection cct is a 'no brainer' and I'm totally puzzled about this extraordinary reluctance to use such a common sense addition - there are any number of good, reliable, low resistance, etc, etc modules (from Asia, for example) that cost little and work off easily acquired voltages already in the power amp.
For those people that have a 'thing' about possible relay problems, there are quite a few designs availably (also on this site) that use low Rdson power Fets/Transistors and are also quite simple and cheap to build."
Good advice. Bought a small protection board kit on eBay from China... $6 including shipping! I remember that I used one of these before, when I build a small chip amp for a friend. Never had it tested in a real music situation, but the circuit design looks OK.
"To me, adding a dc protection cct is a 'no brainer' and I'm totally puzzled about this extraordinary reluctance to use such a common sense addition - there are any number of good, reliable, low resistance, etc, etc modules (from Asia, for example) that cost little and work off easily acquired voltages already in the power amp.
For those people that have a 'thing' about possible relay problems, there are quite a few designs availably (also on this site) that use low Rdson power Fets/Transistors and are also quite simple and cheap to build."
Good advice. Bought a small protection board kit on eBay from China... $6 including shipping! I remember that I used one of these before, when I build a small chip amp for a friend. Never had it tested in a real music situation, but the circuit design looks OK.
Here ya go...... speaker protection, "soft start" thru the CL-60's, and AC fans running at reduced voltage/speed to keep noise done. Th speaker protection modules were via eBay.
http://www.diyaudio.com/forums/pass...ifferent-drummer.html?highlight=music+drummer
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Easy peasy if mosfet go 99% times is shorth circuit = suply rail to speakers
Soft start is easy CL 60 in parralel with relay contact relay closes after delay
ONE realy need CL60 with big cap banks charging up
NTE7100 and Amplimo duble contacts realy for speaker protection
I still have working speakers
http://www.diyaudio.com/forums/pass-labs/188608-my-f5.html
Hello everyone.
I have been reading up on building amps for only a few days, but I'm very interested to actually give it a shot. I did not read any of the 1335 pages in this thread, but I've read JojoD's guide on how to build this F5. I have never build anything like this before and really I don't know much about the whole diy-audio-thing at all. Is building this amp a good start to acquire a new hobby?
I have a few technical questions, as well. The huge current which flows through my circuit at startup, how is this counteracted? Where should I read up to understand what's going on? I don't want anything, in case I start building this, to go extremely wrong. A question about this particular amplifier: it is an A-class amp and I pay .26€ per kWh. How much idle power consumption am I looking at and how much does it consume when it's active? Do I really need the 25W maximum output which it's rated at and if I decrease that, how is it done (simply by reducing the +- V?) and does it actually make the amplifier any more efficient?
I hope this is the right place to ask.
I have been reading up on building amps for only a few days, but I'm very interested to actually give it a shot. I did not read any of the 1335 pages in this thread, but I've read JojoD's guide on how to build this F5. I have never build anything like this before and really I don't know much about the whole diy-audio-thing at all. Is building this amp a good start to acquire a new hobby?
I have a few technical questions, as well. The huge current which flows through my circuit at startup, how is this counteracted? Where should I read up to understand what's going on? I don't want anything, in case I start building this, to go extremely wrong. A question about this particular amplifier: it is an A-class amp and I pay .26€ per kWh. How much idle power consumption am I looking at and how much does it consume when it's active? Do I really need the 25W maximum output which it's rated at and if I decrease that, how is it done (simply by reducing the +- V?) and does it actually make the amplifier any more efficient?
I hope this is the right place to ask.
there is a lot of articles to read on the Firstwatt site. FIRST WATT
as for the consumption. a 3-way spot ligtht with 50W spots draws just about the same amount of Power
the power output is determand by the rail voltage. class A power is determand by the bias current.
if you feel you don't need all that class A power, you can lower the bias and maybe increase the voltage. then you get a lot of headroom. the amp will go into class A/B when it runs out of class A current.
as for the consumption. a 3-way spot ligtht with 50W spots draws just about the same amount of Power
the power output is determand by the rail voltage. class A power is determand by the bias current.
if you feel you don't need all that class A power, you can lower the bias and maybe increase the voltage. then you get a lot of headroom. the amp will go into class A/B when it runs out of class A current.
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The amplifier circuit does not experience this, but the power supply has a large
inrush to charge the capacitors. This is suppressed by the thermistors in
series with the AC line.
An F5 might be a tad ambitious for a first project. I bought a learner's kit like this one for starters:
Amazon.com: Elenco AmeriKit Learn to Solder Kit: Toys & Games
Then graduated to a Hagerman phono stage, head amp, and for my first mains current device, a power supply. Anything that plugs in needs to be built according to safety standards for obvious reasons. I also recapped various pieces of vintage gear. These experiences prepared me for the Pass Pearl 2 and F5.
If you do decide to go for it, you'll find plenty of help here, just ask!
nebiki -
The F5 is a fine place to start. Although if you have never even soldered before I would suggest a pair of AmpCampAmps - Amp Camp Amp Complete Kit - Parts and chassis - Amp Camp Kit - Kits These are great amps and there is quite a lot of simplification because the use an off-the-shelf power supply.
Since you are interested in the F5, I would look at this guide, it has lot's of good information.
http://www.diyaudio.com/forums/pass-labs/188691-illustrated-guide-building-f5.html
But you ask if this is a good amp to start a hobby? Yes, it certialny is! The 'problem' is that the F5 is genuinely so good that you will have a hard time going back to 'regular' hifi!
The F5 is a fine place to start. Although if you have never even soldered before I would suggest a pair of AmpCampAmps - Amp Camp Amp Complete Kit - Parts and chassis - Amp Camp Kit - Kits These are great amps and there is quite a lot of simplification because the use an off-the-shelf power supply.
Since you are interested in the F5, I would look at this guide, it has lot's of good information.
http://www.diyaudio.com/forums/pass-labs/188691-illustrated-guide-building-f5.html
But you ask if this is a good amp to start a hobby? Yes, it certialny is! The 'problem' is that the F5 is genuinely so good that you will have a hard time going back to 'regular' hifi!
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Thank you for all your replies and encouragement. I will be practicing my soldering before I start on the real task and I'm quite sure I'll check everything 10-fold before carrying on. I have also understood the use of the thermistor on the mains after realizing that you're supposed to use a 10 ohms thermistor.
About these components: I effectively weaken the transformer by using them, right? How far am I allowed to go with this? Using a 10ohms thermistor on 230V I'm still running a few hundred amps through the power supply at startup so I'd rather choose a higher resistance, like 16 or 22 (which are available at 3A ratings). How hot are they usually running (so I can estimate the resistance when the amp is turned on) and which resistance would still be acceptable to get adequate power out of the transformer (assuming that I use 24V rails on that recommended 400VA)?
I'm still wondering if just decreasing the voltage of the rails would be sufficient to run the amp at lower power or if any other adjustments were necessary to achieve that. Is it recommended to cut on the power of this amp or should it run as is to achieve the best results?
@ crcook: actually, you didn't discourage me at all, your words were the most encouraging "there is no reason why you could not build an F5.... go sowly and check your work."
I'm afraid I have another question, a very stupid one: do I need those PCBs? I've soldered some very basic circuits before and connected them with wires on the other side of the board. I could totally imagine it's possible to wire this circuit, too, as it doesn't look too complicated on the schematic. Bad idea?
About these components: I effectively weaken the transformer by using them, right? How far am I allowed to go with this? Using a 10ohms thermistor on 230V I'm still running a few hundred amps through the power supply at startup so I'd rather choose a higher resistance, like 16 or 22 (which are available at 3A ratings). How hot are they usually running (so I can estimate the resistance when the amp is turned on) and which resistance would still be acceptable to get adequate power out of the transformer (assuming that I use 24V rails on that recommended 400VA)?
I'm still wondering if just decreasing the voltage of the rails would be sufficient to run the amp at lower power or if any other adjustments were necessary to achieve that. Is it recommended to cut on the power of this amp or should it run as is to achieve the best results?
@ crcook: actually, you didn't discourage me at all, your words were the most encouraging "there is no reason why you could not build an F5.... go sowly and check your work."
I'm afraid I have another question, a very stupid one: do I need those PCBs? I've soldered some very basic circuits before and connected them with wires on the other side of the board. I could totally imagine it's possible to wire this circuit, too, as it doesn't look too complicated on the schematic. Bad idea?
I thought so. When I was thread milling I thought that it was best to have the PCB on the bottom side of the heatsinks, but after looking at some build pictures of different people I noticed that everyone was mounting the PCB's the other way around. That's why I started to wonder if it would matter how to bold the PCB's to the heatsinks. Now I can leave the heatsinks as they are
I'll toss in my two cents. I have been building chip based amps for several years and always had the Pass offerings in the back of my mind. The biggest area of learning was the use and placement of the - (negative) elements of the circuit. It makes sense now, but I'll admit I was lost without prior experience of these designs. As suggested, I proceeded very slowly and asked questions here and in PMs before making a move I wasn't sure about. These guys are fantastic in offering all the help needed to build an amp safely and successfully.
My path was the ACA, then an F5, and now I'm confident enough to tackle the BA-3. Those first two are not that costly to build, and represent a very nice learning experience. That would be my suggested approach.
Wherever one wants to start - just jump in. Ask lots of questions and keep safety prime in your mind. You'll end up with a great amp (or two) and make some nice friends along the way.
My path was the ACA, then an F5, and now I'm confident enough to tackle the BA-3. Those first two are not that costly to build, and represent a very nice learning experience. That would be my suggested approach.
Wherever one wants to start - just jump in. Ask lots of questions and keep safety prime in your mind. You'll end up with a great amp (or two
) and make some nice friends along the way.