Yes you should double check all CBE connections on all your to92 transistors.
apexaudio
Thanks for response.
I have measured bias and:
-input is 2,5mA (total)
-VAS is 7,3mA (I do not know If it is enough but it is cool enough to fitt to92 large pack toshibas there)
-outputs biased at 100mA per device
I am building my next amp with EF3 output stage and j-fet input but still can not decide which way to go, ''Pure Push-Pull'' or classic as ax14 (VAS with courrent source).
Maybe you can advise me about temperature compensation in EF3,
I am going to use 2 pairs of output transistors and can I use single BD139-16 (or maybe some of super-beta transistor ) for temperature compensation ? Or use double transistor compensation like NPN - PNP style ?
Thanks
Thanks for response.
I have measured bias and:
-input is 2,5mA (total)
-VAS is 7,3mA (I do not know If it is enough but it is cool enough to fitt to92 large pack toshibas there)
-outputs biased at 100mA per device
I am building my next amp with EF3 output stage and j-fet input but still can not decide which way to go, ''Pure Push-Pull'' or classic as ax14 (VAS with courrent source).
Maybe you can advise me about temperature compensation in EF3,
I am going to use 2 pairs of output transistors and can I use single BD139-16 (or maybe some of super-beta transistor ) for temperature compensation ? Or use double transistor compensation like NPN - PNP style ?
Thanks
Attachments
Just for curiosity I have connected diode to lower vas transistor (didnt adjust the rest of the currents yet). Bellow just for compare 15Vp-p at 8R load.
The phase shift transistor is only 275uA now it is bit too low, circuit need some adjustment (I try to test it later on). BTW the output transistor bias is very stable - so thumbs up.
It looks like the first prototype had more 2nd harmonic and very low 3rd one.
So prapobly better stick with the 2nd one.
The phase shift transistor is only 275uA now it is bit too low, circuit need some adjustment (I try to test it later on). BTW the output transistor bias is very stable - so thumbs up.
It looks like the first prototype had more 2nd harmonic and very low 3rd one.
So prapobly better stick with the 2nd one.
Attachments
Hi again,
Many thanks Mr. Mile, the amplifier is worked ok now.
This is corrected placement of all TO92 transistors if you are use 2N5551 and 2N5401 (see attachment)
My power supplies are +/-42V and +/-56V. You can see the output signal vs power supply on a picture 2 below:
The resistors in commutator circuit with value 2k2 are very hot and I think their value should be change with 10k or replaced with 1W resistor instead 0.25W.
The commutator circuit is attached below
Attachments
i have 2 x 24-0-24 5 amper traffo can i use it for 2 ax11?
https://www.facebook.com/pages/Vish...4249738966975?ref=stream&hc_location=timeline
https://www.facebook.com/pages/Vish...4249738966975?ref=stream&hc_location=timeline
I built 3EF OPS base on Ostripper design (not exactly same but construction is same). Please see http://www.diyaudio.com/forums/solid-state/248105-slewmaster-cfa-vs-vfa-rumble.html
Just make sure your TO-92 transistor (specially on first stage) is made from the same manufacturer otherwise if they are the same value but different manufacturer will result this high DC offset.
