offset
Good morning,
I´ve finished my Babelfish J with 20V-transformers, three IRFP240, 0,47R (R2…R6).
When setting the offset, I get the following results:
Directly after turn on, the offset is about - 700 mV (520 mV over R2 … R6),
half an hour later there is - 200 mV (495 mv over R2),
after one hour I have about - 100 mV,
after two hours - 40 mV with 490 mV over R2 (the heatsinks have a temperature of 53 degrees).
Is this a normal behavior? With that high starting offset can I connect the amp to the loudspeakers?
Best regards, Axel
Good morning,
I´ve finished my Babelfish J with 20V-transformers, three IRFP240, 0,47R (R2…R6).
When setting the offset, I get the following results:
Directly after turn on, the offset is about - 700 mV (520 mV over R2 … R6),
half an hour later there is - 200 mV (495 mv over R2),
after one hour I have about - 100 mV,
after two hours - 40 mV with 490 mV over R2 (the heatsinks have a temperature of 53 degrees).
Is this a normal behavior? With that high starting offset can I connect the amp to the loudspeakers?
Best regards, Axel
everything as normal , be sure to set both Iq and DC offset at temp equilibrium
initial offset will be lower with load connected , nothing to worry about , even if you use Lowthers
initial offset will be lower with load connected , nothing to worry about , even if you use Lowthers
Attachments
Hi Zen.
yes I saw it. but I mean did you test with it ?
because it seem happened to current source .
yes I saw it. but I mean did you test with it ?
because it seem happened to current source .
Did you try modify control by slip current source? it will no have this trouble with clip.
naah , not worthy of hassle
addition of (5V1 or 5V6 ) zenner is good enough and , besides that , I'm not so interested in using any amp while clipping
so , no reason to improve it further
addition of (5V1 or 5V6 ) zenner is good enough and , besides that , I'm not so interested in using any amp while clipping
so , no reason to improve it further
Zen Mod:
In your listing of parts in Post # 63, am I correct that you indicate that the 2N3820 could be used as an alternative to the J271? Is the 2N3820 a drop-in alternative with no other changes to the circuit involved?
In your listing of parts in Post # 63, am I correct that you indicate that the 2N3820 could be used as an alternative to the J271? Is the 2N3820 a drop-in alternative with no other changes to the circuit involved?
sorry - that's just Eagle generated BOM
what you see is just part's physical layout compatibility ,part's package info , whatever
certainly not electrical equivalency
whatever , looking at 2N3820 datasheet ......... that one is simply too wimpy for task , nearly not enough xconductance (read - intrinsic gain and cojones)
what you see is just part's physical layout compatibility ,part's package info , whatever
certainly not electrical equivalency
whatever , looking at 2N3820 datasheet ......... that one is simply too wimpy for task , nearly not enough xconductance (read - intrinsic gain and cojones)
Hi Zen Mod,
thanks for your question. Yes, it´s singing, very dynamic and colorful sound, much better than my old aleph 4 monos. Now I don´t use my rel stadium subwoofer!
Your question led me to do some cable dressing, to reduce the small hum I heard in front of my speakers - the pictures are "before". And after carefull tightening the screws which hold the two transformers they became quiet too ;-).
Thanks again for your help and the babelfish j.
Hope I get the mobile phone pictures uploaded.
Best regards,
Axel
thanks for your question. Yes, it´s singing, very dynamic and colorful sound, much better than my old aleph 4 monos. Now I don´t use my rel stadium subwoofer!
Your question led me to do some cable dressing, to reduce the small hum I heard in front of my speakers - the pictures are "before". And after carefull tightening the screws which hold the two transformers they became quiet too ;-).
Thanks again for your help and the babelfish j.
Hope I get the mobile phone pictures uploaded.
Best regards,
Axel
Attachments
those being depletion mode devices (normally ON , asking negative g-s voltage for biasing , same as triode) and also having somewhat biggish Ugs for our range of currents (up to 2A) , I can't see them in this type of circuit
considering that JFets are depletion devices - in this circuit no , without major redo
I have something in prototype stage , adequate for whatever type of output you toss in (tnx to myriad of breadcrumbs Papa spilled around) , but I'm always short in time so I can't give you any promise about when
so , easiest is , if you're interested in other devices - to find something comparable to Semisouth SJEP series
look around for Aleph Jango - some , in fact almost all , angles are covered there
I have something in prototype stage , adequate for whatever type of output you toss in (tnx to myriad of breadcrumbs Papa spilled around) , but I'm always short in time so I can't give you any promise about when
so , easiest is , if you're interested in other devices - to find something comparable to Semisouth SJEP series
look around for Aleph Jango - some , in fact almost all , angles are covered there