Hi guys...
I am a beginner in DIY and I am studying Aleph amps.
There are two questions about Aleph.
1) I want to know the role of the 75R resistor in the bottom right corner.
Almost all Alephs have different resistor values.
a30-392r a60-221 a3-100r a2-150r a5-75r j-392r mini-100r.
Why does this wide variation exist?
What makes this difference in sound?
2) Does the a5 input connection work without a jumper or selector?
I know that the input of a30 should be chosen by the jumper. Aleph J is the same.
Is it complete(?) a5 design? Even without a selector?
1) The two resistors connected to the base of the MPSA18 form a voltage divider. The variation of value reflect the different operating voltages in the amplifiers you listed.
2) The Aleph 5 can be operated with either a balanced or unbalanced source. If you choose to feed it an unbalanced source, you should short the negative side to ground, or you will have less gain.
2) The Aleph 5 can be operated with either a balanced or unbalanced source. If you choose to feed it an unbalanced source, you should short the negative side to ground, or you will have less gain.
Thanks.
Further questions ...
1) a3 and a30 have same ± 25 operating voltage.
However, it has a very different resistor value. Is this due to differences of inputs circuit?
2) If the negative and ground are shorted on the circuit, the gain is 20 times.
I think it's wrong ... is not it?
And, I wonder if this circuit can receive balanced input without modification.
Further questions ...
1) a3 and a30 have same ± 25 operating voltage.
However, it has a very different resistor value. Is this due to differences of inputs circuit?
2) If the negative and ground are shorted on the circuit, the gain is 20 times.
I think it's wrong ... is not it?
And, I wonder if this circuit can receive balanced input without modification.
Thanks for the pdf.
But I want to repeat the question again.
1) In a5, if a negative and ground are shorted, the resistance value toward the ground becomes 5K. Is this right?
And if so, do commercial original a5 have jumper or selector?
2) what difference does a3 and a30 make due to their resistance value 100R and 392R?
But I want to repeat the question again.
1) In a5, if a negative and ground are shorted, the resistance value toward the ground becomes 5K. Is this right?
And if so, do commercial original a5 have jumper or selector?
2) what difference does a3 and a30 make due to their resistance value 100R and 392R?
It is just a simple, straightforward solution. Look at the picture of the back of my Aleph J build in the post linked below and you will see an example of that jumper. It is just a bent piece of copper wire.
http://www.diyaudio.com/forums/pass-labs/224881-aleph-universal-mounting-spec-13.html#post3481260
http://www.diyaudio.com/forums/pass-labs/224881-aleph-universal-mounting-spec-13.html#post3481260
It basically adjusts current limiting to provide symmetrical clipping.
If you're building one just remove the current limiting circuit.
I think I understand about a30 and j.
In the case of unbalanced input, the amplification rate of a30 is (100/8.6)+1=12.6 times
j is (221/22.1)+1=11 times
However, in the same way, a5 is (100/5)+1=21 times.
Am I wrong?
Remove it? Is not it too violent?
So how, and how much do a30 and a3 each employ current limiting?
you gave plenty of 1) and 2)
1)more like 57K (balanced Rin aroundish 20K , SE Rin arooundish 57K)
2) which positions exactly ? I don't like speaking generally , when references are mandatory
Remove it? Is not it too violent?
So how, and how much do a30 and a3 each employ current limiting?
Go read aleph circuit reloaded.
you gave plenty of 1) and 2)
1)more like 57K (balanced Rin aroundish 20K , SE Rin arooundish 57K)
2) which positions exactly ? I don't like speaking generally , when references are mandatory
Perhaps I am misunderstanding many things.
Will you show me how you calculated Rin?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.