Maybe one of your ZTX is turned wrong way.In fact happened to me first time I tried mine!!!But the 2 ZTX were reversed.In that case I had overbias problems,no good working points and...quickly pulled out the mains!!!
It is true that the ZTX don't have usual TO92 package,so it gets easy to make a mistake at that point.
Try them out with small multimeter with hfe test to confirm good orientation,gain should be around 100 if you read 10 the pins are not well oriented 😉
Cheers
It is true that the ZTX don't have usual TO92 package,so it gets easy to make a mistake at that point.
Try them out with small multimeter with hfe test to confirm good orientation,gain should be around 100 if you read 10 the pins are not well oriented 😉
Cheers
HOORAY !! It's working at last !
Had to change the ZTX (q4) on one channel after checking the output fets were ok. Funny thing is the ztx measured ok on the hfe multimeter tester but I changed it as a last resort and the problem is over. On the other channel I found a burnt output fet
and replaced it. Then I made a huge mistake. I decided that since the ouput transistors were not getting that hot at the 324mA that I was using to check them out with the power supply I would test the board without mounting the fets on the heatsinks (its all on one board) for a minute just to see if everything was working before bolting everything on again. Well in about 30-40 secs I saw in horror the 6W 350C rated source resistors start to crackle and glow red hot as I dived for the mains switch. Of course I had blown 3-4 fets and I replaced them as well as the resistors. The next time I took no chances, mounted everything and everything worked fine. Now to my first impressions on SOUND:
I am an audiophile for 25 yrs and have auditioned and heard quite a few amplifiers. I have had a Jadis tube integrated in my system and more recently a Naim 250 which has its own cult following in the UK and elsewhere. Recently I auditioned the Naim monoblock amplifiers (~ 5000-6000 USD) and even the flagship 500 amp (~ 16000 USD). I also auditioned Audio Note SET amplification ( 6000 USD).
I can say that I didn't expect the ALeph to sound as good as it did. In my opinion it is much better than my Naim , better than the Naim monoblocks and in the same league as the super expensive Naim 500. It had many of the attributes of the Audio Note amp being very natural sounding and involving. The soundstage was very deep and enveloping and you felt being drawn into the music rather than marvelling at the hi-fi side of the presentation. The natural sound of the timbres and nuances of vocals and piano. strings and brass were really excellent , probably the best I have heard. Rhythm and timing were well preserved but not as excellent.Bass extension and definition were ok but I would have liked more. Having said that I realize that timing and bass are the first to suffer when the amp is still new. I remember my Naim amp sounded pretty slow and thick the first 48 hours so I expect an improvement in this area and a general opening up even more of the sound. Unfortunately (or fortunately as the case may be) I am leaving on holidays tomorrow and I cannot post pictures until I get back.
Finally I would like to say that this was my first electronic project of any kind unless you count soldering some interconnects and speaker cables. So I am more than pleased with myself for getting the results that I did. If I was a car enthusiast it would probably feel like I was able to build my own Ferrari!!
Many thanks to Nelson Pass for sharing his knowledge and to everybody on this Forum for helping me decide that it was a worthwhile adventure.
Had to change the ZTX (q4) on one channel after checking the output fets were ok. Funny thing is the ztx measured ok on the hfe multimeter tester but I changed it as a last resort and the problem is over. On the other channel I found a burnt output fet
and replaced it. Then I made a huge mistake. I decided that since the ouput transistors were not getting that hot at the 324mA that I was using to check them out with the power supply I would test the board without mounting the fets on the heatsinks (its all on one board) for a minute just to see if everything was working before bolting everything on again. Well in about 30-40 secs I saw in horror the 6W 350C rated source resistors start to crackle and glow red hot as I dived for the mains switch. Of course I had blown 3-4 fets and I replaced them as well as the resistors. The next time I took no chances, mounted everything and everything worked fine. Now to my first impressions on SOUND:
I am an audiophile for 25 yrs and have auditioned and heard quite a few amplifiers. I have had a Jadis tube integrated in my system and more recently a Naim 250 which has its own cult following in the UK and elsewhere. Recently I auditioned the Naim monoblock amplifiers (~ 5000-6000 USD) and even the flagship 500 amp (~ 16000 USD). I also auditioned Audio Note SET amplification ( 6000 USD).
I can say that I didn't expect the ALeph to sound as good as it did. In my opinion it is much better than my Naim , better than the Naim monoblocks and in the same league as the super expensive Naim 500. It had many of the attributes of the Audio Note amp being very natural sounding and involving. The soundstage was very deep and enveloping and you felt being drawn into the music rather than marvelling at the hi-fi side of the presentation. The natural sound of the timbres and nuances of vocals and piano. strings and brass were really excellent , probably the best I have heard. Rhythm and timing were well preserved but not as excellent.Bass extension and definition were ok but I would have liked more. Having said that I realize that timing and bass are the first to suffer when the amp is still new. I remember my Naim amp sounded pretty slow and thick the first 48 hours so I expect an improvement in this area and a general opening up even more of the sound. Unfortunately (or fortunately as the case may be) I am leaving on holidays tomorrow and I cannot post pictures until I get back.
Finally I would like to say that this was my first electronic project of any kind unless you count soldering some interconnects and speaker cables. So I am more than pleased with myself for getting the results that I did. If I was a car enthusiast it would probably feel like I was able to build my own Ferrari!!
Many thanks to Nelson Pass for sharing his knowledge and to everybody on this Forum for helping me decide that it was a worthwhile adventure.
Protos,
I'm very glad to hear that you have managed to get the amp working again.
Other than your one "huge mistake", it's just Q4 on one channel and one output transistor on the other channel that is causing all this problem? Could you give us more details please? Is Q4 installed in reversed per hinted by forum member nar?
Also, did you make any changes/rebuilt to the rail fuses?
By the way, are you a professional equipment reviewer? No offense.
I'm very glad to hear that you have managed to get the amp working again.
Other than your one "huge mistake", it's just Q4 on one channel and one output transistor on the other channel that is causing all this problem? Could you give us more details please? Is Q4 installed in reversed per hinted by forum member nar?
Also, did you make any changes/rebuilt to the rail fuses?
By the way, are you a professional equipment reviewer? No offense.
No the q4 was correct because as I said the amp had actually played good music before it blew the fuse and I did double check its orientation. It is funny though that although it measured ok on the tester changing it brought the amp to life. It was showing about 3.3v and the q5 5.8v so both were off base but I suspected it was the one with the lower output that might be the problem. Because everything is interconnected it's difficult to say whether the problem lies with q4 or q5 or it is a blown current source or gain source transistor. You just have to check everything properly out of circuit. I did of course change the fuses on the rails that is, I took the protection out and bridged the gap.
I have played the amps now a couple of hours without problems.
On the other amp though it was a blown gain source transistor that was causing the problem. Heat sink temps are around 48 C but the transistors themselves are very hot. It also depends where you measure. Every couple of centimeters further away from the transistor is 10C cooler.
I have played the amps now a couple of hours without problems.
On the other amp though it was a blown gain source transistor that was causing the problem. Heat sink temps are around 48 C but the transistors themselves are very hot. It also depends where you measure. Every couple of centimeters further away from the transistor is 10C cooler.
No , But i wouldn't mind being sent all the best equipment to listen at home at my leisure. So if you know of any vacancies....
The language that I used was an attempt to do justice to the excellent sounding Aleph. It is a 5 by the way in monoblock cinfiguration using X4 output devices with 500va trans and 2x47000uF Aerovox caps per channel. OFC cabling. I put in some Black Gate electrolytics. Heat sinks are 250mmx300mm X2 on each monoblock. Otherwise the rest of the components are the usual.
The language that I used was an attempt to do justice to the excellent sounding Aleph. It is a 5 by the way in monoblock cinfiguration using X4 output devices with 500va trans and 2x47000uF Aerovox caps per channel. OFC cabling. I put in some Black Gate electrolytics. Heat sinks are 250mmx300mm X2 on each monoblock. Otherwise the rest of the components are the usual.
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