Low Voltage
Hi Samoloko,
I don't know your circumstances. But, I too had slightly low rails on one of my builds -- about 22V or so. It's probably from one of the following:
1. low mains voltage
2. tramsformer's specs and regulation are such that you get lowish secondary voltage
or
3. you're dropping too much voltage across the dropping resistors
Steve
Hi Samoloko,
I don't know your circumstances. But, I too had slightly low rails on one of my builds -- about 22V or so. It's probably from one of the following:
1. low mains voltage
2. tramsformer's specs and regulation are such that you get lowish secondary voltage
or
3. you're dropping too much voltage across the dropping resistors
Steve
with shottky diodes you'll have somewhat higher voltage , but not much .
just compare voltage sag across plain vs. shottky diodes , and you'll know .
Papa uses plain bridges in his F amps ,at least to my knowledge
Industrial Strength F5:
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I live in the Netherlands and there are not so many options for transformers to use in the F5.
RS Components sells some excellent 18 V AC trannies that are shielded and dead quiet. However the maximum they offer for 18 V AC is 225 VA.
http://nl.rs-online.com/web/search/s...duct&R=2238825
I guess that is not really enough for two channels F5.
My intention is to build a stereo amp that uses 2 F5 in parallel per channel, so 4 F5 amps for a stereo amp. I also use the CViller PSU boards.
My question to the more experienced:
Can I use two of these 225 VA trannies to feed one PSU board that will feed 2 F5 amp boards, without running into trouble with hum or sound degradation? (Of course I would be forced to use the outputs of the trannies in parallel and use one for the positive rail and one for the negative rail).
Or is it neccesary to use two PSU boards for one channel? That would make 4 PSU boards for the stereo amp, and since I want to use chokes (CLC instead of CRC) that would require 8 chokes, which calls for a lot of space and money!
Or is this the preferred route?
Please can some expert give me advice?
Thanks!
Lucas
RS Components sells some excellent 18 V AC trannies that are shielded and dead quiet. However the maximum they offer for 18 V AC is 225 VA.
http://nl.rs-online.com/web/search/s...duct&R=2238825
I guess that is not really enough for two channels F5.
My intention is to build a stereo amp that uses 2 F5 in parallel per channel, so 4 F5 amps for a stereo amp. I also use the CViller PSU boards.
My question to the more experienced:
Can I use two of these 225 VA trannies to feed one PSU board that will feed 2 F5 amp boards, without running into trouble with hum or sound degradation? (Of course I would be forced to use the outputs of the trannies in parallel and use one for the positive rail and one for the negative rail).
Or is it neccesary to use two PSU boards for one channel? That would make 4 PSU boards for the stereo amp, and since I want to use chokes (CLC instead of CRC) that would require 8 chokes, which calls for a lot of space and money!
Or is this the preferred route?
Please can some expert give me advice?
Thanks!
Lucas
RS components are usually quite expensive when it comes to transformers. I would try seaching for a local manufacturer, who will make the transformers to your exact requirements. In Australia we have Harbuch http://www.harbuch.com.au/toroids1.htm , he builds an absolute quality product to whatever requirements you would like. I am not neccessarily suggesting you should buy from him, but maybe have a look around locally for someone like him.
I am now seriously considering doing monoblocks with this amp.
So P Channel and N Channel output mosfets will be on sepparate heatsinks (ie on each side of the amplifier case).
Will there be any problems in doing this?
I guess this is what is done in the XA 60.5 monoblocks. So it should be doable.
Any advice on this would be appreciated.
So P Channel and N Channel output mosfets will be on sepparate heatsinks (ie on each side of the amplifier case).
Will there be any problems in doing this?
I guess this is what is done in the XA 60.5 monoblocks. So it should be doable.
Any advice on this would be appreciated.
Check amplimo.nl. They offer 300VA, 500VA, 625VA, 800VA toroids with twin 18V secondaries. 500VA should be enough for a F5. Can be bought online @ deaudiofabriek.nl. Success!
I'm doing exactly the same thing, except mine will be uncased.
Peter's F5 is built like this as well, and his PCB is perfect for such a task as the devices are facing each other on the opposite sides of the PCB. Of course I will be running open chassis so the ~2" width of the entire assembly does not bother me.
Andrew posted some open questions regarding this arrangement, specially as the output offset depends on the temperature/operating point balance between the two halves and separating them like this means they can't 'talk' to each other. Peter uses a metal sheet to connect the two halves. I'm still wondering what to do, but probably I'll have a thick sheet of aluminum as the 'front panel' connecting the two halves, sliding into the slot on the heatsink.
Nice chassis. Did you make it yourself?
They were offered out by another diyaudio-r, and I haven't see 'em in quite a while --
My usual amplifier box is recycled Hewlett Packard or Kepco power supply,and my heat sinks are military or industrial surplus. Because of WAF I use Audio Research in the public rooms of the household.
Edit, the listening room isn't public -- it has a Grizzly mill, an AP analyzer, my modified Thors, a pair of TM5006 mainframes, solder and rework stations, Heath power supplies, HP HV power supplies, a new sony CD/SACD player, tuner which (by intent) only receives AM radio, much-modded Adcom GFP565, a beat up Acoustic Research SP-11, and of course several F4 and F5 amplifiers.
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I've recently bought two 300VA 2x 18V toroids directly from the amplimo site. Emailed the guy if he could pot them into metal cans. And they do, that it looks very nice i will post some pictures later on.
Here's another source for transformers:
http://www.toroidy.pl/index.php?option=com_content&task=view&id=6&Itemid=13
They have a range specially made for audio, good prices too.
http://www.toroidy.pl/index.php?option=com_content&task=view&id=6&Itemid=13
They have a range specially made for audio, good prices too.
how much cost additional center potting
Is there Interest at toroidy If so I will buy 1 or 2
I have used a couple of their transformers in my Patak style gainclone - they work extremely well; however in the UK we are now at a disadvantage (GBP vs EUR), but elsewhere in Europe I expect their prices are still good.
Ps these are the transformers I believe PD uses for his own Pateks (apologies Peter if that is not the case)