Not sure about this. Some experts may comment.
You need more driving current with 6, 8 or 10 output pairs. Some REAL experts may comment on this.
Nelson recommend it together with changes in the feedback loop in the Turbo article if we use more output pairs (page 14)
Another question:
Will you produce these boards?🙂
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Chassis is more expensive than outputs , it should be easy to do mono if boards are l/r , 4 pr / ch is an optimum balance of sonics /power /heat ....
Hope you realise that using TO-247 dual cathode diodes for a 2x4 parallel output stage is bad economics.
+$45 for stereo, in comparison to cheapo TO-220 that also handle 2x15A each .
TO-247 lead holes are only interesting for a twit who bought them by the thousand.
+$45 for stereo, in comparison to cheapo TO-220 that also handle 2x15A each .
TO-247 lead holes are only interesting for a twit who bought them by the thousand.
For making a jokey ?
(would be a first time)
Anyway, for a bad example : http://www.vishay.com/docs/88892/mbr60100.pdf
Requirements would be :
- Low resistance (duh)
- Vf preferably higher than 0.5V at ~zero current
- Smooth transition
Moi, i'd thermally couple the diodes (plus select matching ones from stinking stash)
(would be a first time)
Anyway, for a bad example : http://www.vishay.com/docs/88892/mbr60100.pdf
Requirements would be :
- Low resistance (duh)
- Vf preferably higher than 0.5V at ~zero current
- Smooth transition
Moi, i'd thermally couple the diodes (plus select matching ones from stinking stash)
2 big questionS
Supose you pay attention to what Papa said and don't use more than 50W dissipation on each of the mosfets.
Amplifier is suplied by positive and negative voltages of +25 and - 25 V
Example 25 V rails 2 A (this is the easy DC bit)
and supose that your amplifier clips at about 2 volts from the suply rails 23 V
Each rail contribute half the current or current is = 2 X bias current to stay in class A
Now the speakers aledgedly have impedence as low as 4 Homs (alegdgedley or just to make things simple)
What would be the current needed to stay in class A for 25 V rails
And for 35 V rails ?
50W dissipation = 1.4 A bias on each more or less
As soon as route mean square came up I get flied so can somebody do the mats for me please.
Real question
1) Do one realy need 4 mosfets on each rail for 35 V rails?
2 )How low can your speaker impedence be if you have 35 V rails and bias for each rail is set at 5.5 A ?
3) do one need to stay in class A till the amplifier clip?
Supose you pay attention to what Papa said and don't use more than 50W dissipation on each of the mosfets.
Amplifier is suplied by positive and negative voltages of +25 and - 25 V
Example 25 V rails 2 A (this is the easy DC bit)
and supose that your amplifier clips at about 2 volts from the suply rails 23 V
Each rail contribute half the current or current is = 2 X bias current to stay in class A
Now the speakers aledgedly have impedence as low as 4 Homs (alegdgedley or just to make things simple)
What would be the current needed to stay in class A for 25 V rails
And for 35 V rails ?
50W dissipation = 1.4 A bias on each more or less
As soon as route mean square came up I get flied so can somebody do the mats for me please.
Real question
1) Do one realy need 4 mosfets on each rail for 35 V rails?
2 )How low can your speaker impedence be if you have 35 V rails and bias for each rail is set at 5.5 A ?
3) do one need to stay in class A till the amplifier clip?
No square root here.
For staying class A you need twice the current into 4 ohms than into 8 ohms.
Example
25v rails
50w classA 4 ohms
Twin outputs biased 1.3 each.
33v rails
100w class A into 4 ohms
Four outputs biased 0.85A each
For staying class A you need twice the current into 4 ohms than into 8 ohms.
Example
25v rails
50w classA 4 ohms
Twin outputs biased 1.3 each.
33v rails
100w class A into 4 ohms
Four outputs biased 0.85A each
Tanks Bobodioulasso
so to keep dissipation for each mosfets below 50W with 33 V rails I can bias them to about 1.5 A
and they stay in class A even if speaker impedence get down to 2 Homs.
Do one realy need the diodes?
so to keep dissipation for each mosfets below 50W with 33 V rails I can bias them to about 1.5 A
and they stay in class A even if speaker impedence get down to 2 Homs.
Do one realy need the diodes?
Dissipation as long as you stay in class A is
25x1.3=32.5w
or 33x0.85=28.05w
then it continues to increase when you leave classA because of a lower impedance load.
No.
25x1.3=32.5w
or 33x0.85=28.05w
then it continues to increase when you leave classA because of a lower impedance load.
No.
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1.5A per device is ~0.7V drop across a 0R47 drain resistor, and ~1W dissipation.
Don't need no stinkin diodes.
Stays in Class A if it has 4 outputs in parallel.
Don't need no stinkin diodes.
Stays in Class A if it has 4 outputs in parallel.
33v rails?
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Where is it said 50w per device?
Just qoting Papa Pass
" You can get 50 W dissipation out of the big ones and about 40 of litle ones"
refering to sizez of mosfuses
can't remember from where but that bit stuck.
then one thing to tink do one realy need to stay in class A till the amplifier start volt clipping.
And I need to save for bigher trafos 24 V Ac out is bit low now.
Or wait for F6
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Generally, for very low impedance loads one choose lower rails.
Leaving classA is not a problem neither.
Leaving classA is not a problem neither.
If BlackSabby wants 400W dissipation, that's what he gets.
(as me did with KSA50)
I had baby Krell 400 Xi and did not like it
bit like nails on black board.
I know the 50 are different beast but...
Compare that (400) to a F5 one should be rightly proud to have built as first outing on power deviece field.
yeah 400W dissipation
is quite rightbut in theory with sink large enoug or one maybe 2 of those in drawing one could
so one would agree with me, lets stick to one thing just to simplify 33 V rails, to agree with Jaco no need for stink diodes.
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