Never mind
Anyway, this is all too confusing to those who seek advice, and not relevant to builders of F5
Nelson states 6A continious is needed, and 10A peak
2x 18Vac trafos with minimum 10A
360watt trafos pr channel is absolute minimum
500watt pr channel should work fine
Here we can get Amplimo 300, 500, 625, 800VA, with 2x 18Vac
I dont know, but I have always known 500watt toroids to be the upper limit without using softstart
Anyway, this is all too confusing to those who seek advice, and not relevant to builders of F5
Nelson states 6A continious is needed, and 10A peak
2x 18Vac trafos with minimum 10A
360watt trafos pr channel is absolute minimum
500watt pr channel should work fine
Here we can get Amplimo 300, 500, 625, 800VA, with 2x 18Vac
I dont know, but I have always known 500watt toroids to be the upper limit without using softstart
At first glance, i have been thinking you were joking.
But finally i think you are not far from the truth.
100w/8ohms give peaks of 200w corresponding to 5A pk
then, 10Amp pk@4 ohms and 20amp pk@2ohms.
Which correspond to a 2x35v transformer 1400va/ channel.
And not less than350va@8ohm and 700va@4ohms.
The problem is, when you read about this on the web or in books, opinions differ.
Ok, measured voltage is actually 2x 38Vac, 25-30A(?)
Specced by pros doing a balanced 500watt classA, 2000watt AB
I think two of those were used each channel
Water cooling, PC control, motor vario powerup
They did build working proto amps
Aimed at recording studios etc
Not sure they sold any
Well, they are from before anyone thought about classD
These trafos are leftovers
Fun to look at, but have become more of a burden now
Today, I tend to believe that smaller sound better
I have 50watt AB monos with 500watt trafos
With singel pair BJTs they play in 2ohm easily, and still sound nice
I suppose classA is best done BIG, not to have all sorts of heat issues
ClassA is no cheap affair
I have really no interest in classA as such
But I do have interest in F5
And I really like the size, and its elegant "simplicity"
But had it been bigger I wouldnt be here
Specced by pros doing a balanced 500watt classA, 2000watt AB
I think two of those were used each channel
Water cooling, PC control, motor vario powerup
They did build working proto amps
Aimed at recording studios etc
Not sure they sold any
Well, they are from before anyone thought about classD
These trafos are leftovers
Fun to look at, but have become more of a burden now
Today, I tend to believe that smaller sound better
I have 50watt AB monos with 500watt trafos
With singel pair BJTs they play in 2ohm easily, and still sound nice
I suppose classA is best done BIG, not to have all sorts of heat issues
ClassA is no cheap affair
I have really no interest in classA as such
But I do have interest in F5
And I really like the size, and its elegant "simplicity"
But had it been bigger I wouldnt be here
labjr said:
Well, I got lost too
Through many posts there was suggestions and calculations using much smaller trafos, and arguments
But never seem find any conclusion
I just tried to get back on track using numbers from FirstWatt site
6A continious, 10A peak
Thats a minimum of 360watt, and I conclude 500watt pr channel to be ok
All I asked was whether this is ok, or its due time to correct
As you said, too many other confusing suggestions
I have boards from both Cviller and PeterDaniel, and no intention of doing anything else
Cvillers are easier to use, mounted on a single BIG heatsink pr channel
Peters boards are a bit special, and really needs two opposite heatsinks, pr channel
Its the way he have shown he use them himself, they are made especially to used that way
And surely VERY nice for that certain approach
But I would not like to mount Peters boards flat on heatsink, due to the heat
In F5 owners manual 6A continious and 10A peak is recommended, PR CHANNEL
Thats what you say people use for stereo
Do you mind reading F5 owners manual, please
Im sure you could use much less, under certain conditions
Used with 99db 8" FR speaker with a 50hz low limit, playing light chamber music, less would probably work fine
But used with 90db 3-4ohm speakers, going down to 30hz, playing hard rock, what happens then
To me its really not that simple
Anyway, if I remember correctly F5 idles along using 160watt, each channel
Seems to me a 300watt trafo used stereo would be pushed to its limits continiously, and probably run pretty hot
I will also try to shield trafo heat from heatsink heat, somehow
I wonder whether you forget to use the summed voltage rating of both secondary windings, fore calculating total VA of trafo
Thats what you say people use for stereo
Do you mind reading F5 owners manual, please
Im sure you could use much less, under certain conditions
Used with 99db 8" FR speaker with a 50hz low limit, playing light chamber music, less would probably work fine
But used with 90db 3-4ohm speakers, going down to 30hz, playing hard rock, what happens then
To me its really not that simple
Anyway, if I remember correctly F5 idles along using 160watt, each channel
Seems to me a 300watt trafo used stereo would be pushed to its limits continiously, and probably run pretty hot
I will also try to shield trafo heat from heatsink heat, somehow
I wonder whether you forget to use the summed voltage rating of both secondary windings, fore calculating total VA of trafo
tinitus said:
Correction
Its actually 180watt in stereo, sorry
Thats a relief, I was already beginning to sweat
Still, I think there are different needs fore different applications, speakers, music, SPL etc
Anyway, I like that its 1-2ohm stable, able to drive 3-4ohm speakers easily
Or maybe even drive straight 1ohm DIY ribbon tweeters
but if your speakers are 16ohm, you may not need that
I think you're making this too difficult. You should probably build it with the same parts as the original so you have a reference. Then you can try to make changes to the circuit afterward. I don't understand everything. I didn't calculate this. The original uses a 300VA Plitron and we did a Plitron group buy a while back so I bought one.
BTW the amp idles at 62 watts/ ch if built as per the original circuit.
BTW the amp idles at 62 watts/ ch if built as per the original circuit.
Was wondering about that too. 124W total idle dissipation, where is the the other 56W consumed? The factory PS doesn't look like it could burn close to 60W.
Of course I would never bias it stock. I'm using a 1500VA 38V sec trafo running off a variac with 70VAC incoming to the trafo. 27VDC coming into the PS, with 1 volt across R11,R12 which are 0.5R for a 2 amp DC bias, no compensation, no current protection.........hot and sweet.
why not go for 500VA, bigger trafos never hurt anybody, unless your into dropping them on people......then you'd just be crazy.
Of course I would never bias it stock. I'm using a 1500VA 38V sec trafo running off a variac with 70VAC incoming to the trafo. 27VDC coming into the PS, with 1 volt across R11,R12 which are 0.5R for a 2 amp DC bias, no compensation, no current protection.........hot and sweet.
why not go for 500VA, bigger trafos never hurt anybody, unless your into dropping them on people......then you'd just be crazy.