aleph 1.2's to Ax100
Gl and Grey--testing update on my XA100 conversion from my Aleph 1.2.
I have one mono amp finished. My second is on the test bench after replacing the input diff pair again.
Lessons learned:
You cannot depend on the static battery testing for gain using the methods described in the A75 article or in NP's article.
I have measured and matched the input IRF 9610's in my test set up to .000mv and when installed I would get 200mv relative offset between the speaker output terminals. My absolute offset relative to ground is fine as I can get it down to the value of the relative offset.
Right now the pair I have in the amp and testing moves from about 30mv to 130mv so I am guessing I am at about an average of 90mv of relative offset at the speaker output terminals.
Lesson two is my 2mh air core inductors smell from roasting the schalack (spelling?) on the wires due to the heavy current. The wire looks to be 16 guage. Any suggestions? Perhaps getting some wound with 14 or 12 gauge wire would lessen the heat. I do have some iron core 1mh but these saturated. They also have 14 gage wire. They stunk as well. My amp generates about 2.9amps of current per signal side or 5.6amps total. This is a little higher than Gl but I have an extra output device.
My one remaining problem that I haven't been able to solve is that on switch on I still get a transient of .5v at switch on at relative offset. I have a cl60 surge suppressor at the input and I have checked my connections. I suspect a cap or something. The relative offset then slowly settles down to 90mv (+/-50mv).
I hate turn on thumps so I can either try and solve this or put on a delay relay circuit. The other mono amp doesn't seem to have this severe of a turn on surge. It is always something.
The other mono amp also has a bit better relative dc offset.
I also spent a day chasing a gain problem between the +signal output and the - signal output. The gain on one side was double.
As it turned out it was the cheap radioshack alligator clipped test wires I was using between the board connections and the outputs before I did the final solder connections-dah!
I have learned a lot about trying to balance two internal amps into one. I can see why it is harder to manufacture these types of amps as the only real adjustments are due to the devices themselves. This means more labor.
Have a good new year, I hope to hear these this weekend sometime. dave
Gl and Grey--testing update on my XA100 conversion from my Aleph 1.2.
I have one mono amp finished. My second is on the test bench after replacing the input diff pair again.
Lessons learned:
You cannot depend on the static battery testing for gain using the methods described in the A75 article or in NP's article.
I have measured and matched the input IRF 9610's in my test set up to .000mv and when installed I would get 200mv relative offset between the speaker output terminals. My absolute offset relative to ground is fine as I can get it down to the value of the relative offset.
Right now the pair I have in the amp and testing moves from about 30mv to 130mv so I am guessing I am at about an average of 90mv of relative offset at the speaker output terminals.
Lesson two is my 2mh air core inductors smell from roasting the schalack (spelling?) on the wires due to the heavy current. The wire looks to be 16 guage. Any suggestions? Perhaps getting some wound with 14 or 12 gauge wire would lessen the heat. I do have some iron core 1mh but these saturated. They also have 14 gage wire. They stunk as well. My amp generates about 2.9amps of current per signal side or 5.6amps total. This is a little higher than Gl but I have an extra output device.
My one remaining problem that I haven't been able to solve is that on switch on I still get a transient of .5v at switch on at relative offset. I have a cl60 surge suppressor at the input and I have checked my connections. I suspect a cap or something. The relative offset then slowly settles down to 90mv (+/-50mv).
I hate turn on thumps so I can either try and solve this or put on a delay relay circuit. The other mono amp doesn't seem to have this severe of a turn on surge. It is always something.
The other mono amp also has a bit better relative dc offset.
I also spent a day chasing a gain problem between the +signal output and the - signal output. The gain on one side was double.
As it turned out it was the cheap radioshack alligator clipped test wires I was using between the board connections and the outputs before I did the final solder connections-dah!
I have learned a lot about trying to balance two internal amps into one. I can see why it is harder to manufacture these types of amps as the only real adjustments are due to the devices themselves. This means more labor.
Have a good new year, I hope to hear these this weekend sometime. dave
aleph 1.2's to Ax100
Gl and Grey
Second mono amp is ready, my start up pop was due to test leads and when I did the final connections I got 200mv surge at start up on the relative dc offset and then it settles down. Final absolute offset is 323mv after warm up-I am leaving it set there.
I had to adjust down the gain on the positive rail vs the negative rail. I have an 845 ohm resistor on the negative rail and I reinstalled the pot on the positive side and adjusted until both waveforms matched on the scope. When doing the add function on the scope I almost get a straight line now.
I didn't do this on my first mono amp-forgot but even if it is off a touch will I hear it?? Please advise or I will have to tear into the other mono amp.
I definetly will get new heavier gauge inductors to get rid of the roasting ones I have now-dave
Gl and Grey
Second mono amp is ready, my start up pop was due to test leads and when I did the final connections I got 200mv surge at start up on the relative dc offset and then it settles down. Final absolute offset is 323mv after warm up-I am leaving it set there.
I had to adjust down the gain on the positive rail vs the negative rail. I have an 845 ohm resistor on the negative rail and I reinstalled the pot on the positive side and adjusted until both waveforms matched on the scope. When doing the add function on the scope I almost get a straight line now.
I didn't do this on my first mono amp-forgot but even if it is off a touch will I hear it?? Please advise or I will have to tear into the other mono amp.
I definetly will get new heavier gauge inductors to get rid of the roasting ones I have now-dave
Hi Dave,
You seem to be doing a good job of answering your own questions. I don't think there's much I can add. Everything appears to be in the ball park.
Air core inductors need to be really heavy gauge wire in order to keep the internal resistance down and the resulting internally generated heat. The coils that you buy from the speaker supply places are often dipped in varnish to keep the windings from rattling. This varnish is almost guaranteed to be less heat tolerant than the coating on the wire. You're better of to wind your own. Then you can wind them with lots of surface area exposed and that will help dissipate the heat.
I used the 15ga 1mH iron core sledgehammers from Madisound. I figure they are dissipating just less than 3W each. They get slightly warm. They generate a weak magnetic field (I do a screwdriver attraction test - very scientific) that doesn't feel like they're saturating. But even if they are - who cares?. The amps work and sound great. I'm happy.
Oh and Happy New Year. I think you're in for some great listening. This looks to be the year for you to be finishing your line arrays!
Graeme
You seem to be doing a good job of answering your own questions. I don't think there's much I can add. Everything appears to be in the ball park.
Air core inductors need to be really heavy gauge wire in order to keep the internal resistance down and the resulting internally generated heat. The coils that you buy from the speaker supply places are often dipped in varnish to keep the windings from rattling. This varnish is almost guaranteed to be less heat tolerant than the coating on the wire. You're better of to wind your own. Then you can wind them with lots of surface area exposed and that will help dissipate the heat.
I used the 15ga 1mH iron core sledgehammers from Madisound. I figure they are dissipating just less than 3W each. They get slightly warm. They generate a weak magnetic field (I do a screwdriver attraction test - very scientific) that doesn't feel like they're saturating. But even if they are - who cares?. The amps work and sound great. I'm happy.
Oh and Happy New Year. I think you're in for some great listening. This looks to be the year for you to be finishing your line arrays!
Graeme
aleph 1.2's to Ax100
GL-I called my friends over at Meniscus Audio, they can wind me a 1mh 14 gauge iron core inductor. I can try those which is about what you are using. I will listen some tomorrow and then when I get the new inductors all I have to do is dress the wires (shorten them) as I want some run time to make sure everything is ok. I will keep in touch. dave
GL-I called my friends over at Meniscus Audio, they can wind me a 1mh 14 gauge iron core inductor. I can try those which is about what you are using. I will listen some tomorrow and then when I get the new inductors all I have to do is dress the wires (shorten them) as I want some run time to make sure everything is ok. I will keep in touch. dave
Hi,
for coils you could also try torobars from intertechnik. They work fine in my amps at 7A bias. I tested them at 9 or 10A without any problem.
What worries me a bit is that your relative offset is changing all the time. Mine starts at 15mV and during warmup it´ll change to around 12mV. The other channel has a bit more but never differs more than 3 or 4mV during warmup.
William
for coils you could also try torobars from intertechnik. They work fine in my amps at 7A bias. I tested them at 9 or 10A without any problem.
What worries me a bit is that your relative offset is changing all the time. Mine starts at 15mV and during warmup it´ll change to around 12mV. The other channel has a bit more but never differs more than 3 or 4mV during warmup.
William
aleph1.2 to xa100
Hi wuffwaff, I think my changing relative dc offset was due to the fact that I was using test leads to connect my driver board to the output devices and then to the speaker outputs. I don't think that the alligator connections could handle the current plus while adjusting the circuit pots I am sure I was moving these wires. Once I soldered the final connections everything settled down. If I were ever doing a project like this again I would solder in transistor sockets for the differential pair so I could test the matched pairs easier. Like I have mentioned I did the testing in a battery powered circuit to match the transistors perfectly but when put in the final circuit they didn't behave the way they tested. I am using the IRF devices. I am also using wire screw terminals on the board vs soldering directly to the input connector and output devices. I think that this can also cause distortion if not done properly.
Regarding the Inductors, I have measured the 1mh iron core inductors that use 15 gauge wire and they measure at .1 ohm.
I bought these from Meniscus audio
Using 6 output devices per quad I get 2.9amps (rounded) per quad or 5.8amps per inductor.
.1 ohm x 5.8amps gives me a voltage drop of .58volts across the inductor. 5.8amps x .58volts = 3.36 watts to disapate so this should work as far as the heat goes.
I was using air coiled inductors with a resistance of .33 ohms at 2mh. which gives a voltage drop of 1.91 volts x 5.8amps = 11 watts disapation. This caused enough heat to get the varnish on the wires to cook.
I will experiment and get back to you on what worked. I should be listening by this weekend. Thanks for your suggestion, if I can't get the iron core to work than I may get some 12 gauge wires wound on a core. dave
Hi wuffwaff, I think my changing relative dc offset was due to the fact that I was using test leads to connect my driver board to the output devices and then to the speaker outputs. I don't think that the alligator connections could handle the current plus while adjusting the circuit pots I am sure I was moving these wires. Once I soldered the final connections everything settled down. If I were ever doing a project like this again I would solder in transistor sockets for the differential pair so I could test the matched pairs easier. Like I have mentioned I did the testing in a battery powered circuit to match the transistors perfectly but when put in the final circuit they didn't behave the way they tested. I am using the IRF devices. I am also using wire screw terminals on the board vs soldering directly to the input connector and output devices. I think that this can also cause distortion if not done properly.
Regarding the Inductors, I have measured the 1mh iron core inductors that use 15 gauge wire and they measure at .1 ohm.
I bought these from Meniscus audio
Using 6 output devices per quad I get 2.9amps (rounded) per quad or 5.8amps per inductor.
.1 ohm x 5.8amps gives me a voltage drop of .58volts across the inductor. 5.8amps x .58volts = 3.36 watts to disapate so this should work as far as the heat goes.
I was using air coiled inductors with a resistance of .33 ohms at 2mh. which gives a voltage drop of 1.91 volts x 5.8amps = 11 watts disapation. This caused enough heat to get the varnish on the wires to cook.
I will experiment and get back to you on what worked. I should be listening by this weekend. Thanks for your suggestion, if I can't get the iron core to work than I may get some 12 gauge wires wound on a core. dave
aleph 1.2 to AX100
To Gl -many thanks for the support and to Grey and Wuffwaff for your comments. I have finally listened to my AX100 conversion project -- wonderful.
My project goals
1. Find an amp to drive the 24 ribbon tweeters of my line arrays and mate sonically to my Pass 350.5's driving my mid bass drivers.
Crossover pt from 2k to 20k.
2. Revise the amp to get away from the 2kva mechanical transformer hum of my Aleph 1.2's.
3. Learn something new!
4. Have fun in the process and not have to reengineer a new chasis.
5. Sounds like real music based on the source material
I can say finally that items 1,3,4&5 have been very successful. Item 2 remains a work in progress, I get less mechanical noise from the new 1kva trannies than my Aleph 2kva trannies before but they are working really hard and are audible up close.
I finally listened to the amps run full range driving my 24 year lold Watkins WE-1's which present a very severe load in the bass with three 8" acoustic suspension drivers. The amps are harmoncially better than anything else I have heard; the Pass 350.5 driving the same speakers is a little better in the bass and takes less driving power from the preamp. The XA100 reveals how good the Aleph design really was. The XA 100 also for some reason makes the images more life like (including taller). I have to recalibrate from 24 ribbon tweeters to two 1-1/4" audax but the Watkins are 53 inches tall and the image is another foot above that height.
The soundstage is first rate and the details on instrument location (depth and breath) on live recordings is first rate.
I haven't tried to use it yet on my line arrays and I have to recalibrate my ears based on the pt. source design of the Watkins but I am sure based on what I have heard that these amps will preform as good or better than my Pass/Tharagard A75 on the tweeters in my line array in a bi-amp set up.
I don't get any turn on or turn off thump--so far so good. I will listen all week to them run full range and then plug them into my line arrays when I feel that the testing has gone well.
The final measurements are:
Mono right
AC measured at 120hz negative speaker terminal 12.00volts
AC measured at 120hz positive speaker terminal 12.01votls
Relative DC offset between speaker terminals 20mv
Absolute DC offset between speaker terminals and ground-<100mv
Mono left
AC measured at 120hz negative speaker terminal 12.00vots
AC measured at 120 hz positive speaker terminal 12.005mv
Relative DC offset between speaker terminals
To Gl -many thanks for the support and to Grey and Wuffwaff for your comments. I have finally listened to my AX100 conversion project -- wonderful.
My project goals
1. Find an amp to drive the 24 ribbon tweeters of my line arrays and mate sonically to my Pass 350.5's driving my mid bass drivers.
Crossover pt from 2k to 20k.
2. Revise the amp to get away from the 2kva mechanical transformer hum of my Aleph 1.2's.
3. Learn something new!
4. Have fun in the process and not have to reengineer a new chasis.
5. Sounds like real music based on the source material
I can say finally that items 1,3,4&5 have been very successful. Item 2 remains a work in progress, I get less mechanical noise from the new 1kva trannies than my Aleph 2kva trannies before but they are working really hard and are audible up close.
I finally listened to the amps run full range driving my 24 year lold Watkins WE-1's which present a very severe load in the bass with three 8" acoustic suspension drivers. The amps are harmoncially better than anything else I have heard; the Pass 350.5 driving the same speakers is a little better in the bass and takes less driving power from the preamp. The XA100 reveals how good the Aleph design really was. The XA 100 also for some reason makes the images more life like (including taller). I have to recalibrate from 24 ribbon tweeters to two 1-1/4" audax but the Watkins are 53 inches tall and the image is another foot above that height.
The soundstage is first rate and the details on instrument location (depth and breath) on live recordings is first rate.
I haven't tried to use it yet on my line arrays and I have to recalibrate my ears based on the pt. source design of the Watkins but I am sure based on what I have heard that these amps will preform as good or better than my Pass/Tharagard A75 on the tweeters in my line array in a bi-amp set up.
I don't get any turn on or turn off thump--so far so good. I will listen all week to them run full range and then plug them into my line arrays when I feel that the testing has gone well.
The final measurements are:
Mono right
AC measured at 120hz negative speaker terminal 12.00volts
AC measured at 120hz positive speaker terminal 12.01votls
Relative DC offset between speaker terminals 20mv
Absolute DC offset between speaker terminals and ground-<100mv
Mono left
AC measured at 120hz negative speaker terminal 12.00vots
AC measured at 120 hz positive speaker terminal 12.005mv
Relative DC offset between speaker terminals
aleph 1.2 to AX100
To Gl -many thanks for the support and to Grey and Wuffwaff for your comments. I have finally listened to my AX100 conversion project -- wonderful.
My project goals
1. Find an amp to drive the 24 ribbon tweeters of my line arrays and mate sonically to my Pass 350.5's driving my mid bass drivers.
Crossover pt at 2.6k driving to 20k.
2. Revise the amp to get away from the 2kva mechanical transformer hum of my Aleph 1.2's.
3. Learn something new!
4. Have fun in the process and not have to reengineer a new chasis.
5. Sounds like real music based on the source material
I can say finally that items 1,3,4&5 have been very successful. Item 2 remains a work in progress, I get less mechanical noise from the new 1kva trannies than my Aleph 2kva trannies before but they are working really hard and are audible up close.
I finally listened to the amps run full range driving my 24 year lold Watkins WE-1's which present a very severe load in the bass with three 8" acoustic suspension drivers. The amps are harmoncially better than anything else I have heard; the Pass 350.5 driving the same speakers is a little better in the bass and takes less driving power from the preamp. The XA100 reveals how good the Aleph design really was. The XA 100 also for some reason makes the images more life like (including taller). I have to recalibrate my ears from 24 ribbon tweeters to two 1-1/4" audax but the Watkins are 53 inches tall and the image is another foot above that height. When listening to my line arrays which are estimated at 94db efficient vs the 85 to 87 db efficient Watkins: I normally sit 12 to 16 feet from the speakers. With the watkins I have to sit about 10 feet away for best sound.
The soundstage is first rate and the details on instrument location (depth and breath) on live recordings is first rate.
I haven't tried to use it yet on my line arrays and I have to recalibrate my ears based on the pt. source design of the Watkins but I am sure based on what I have heard that these amps will preform as good or better than my Pass/Tharagard A75 on the tweeters in my line array in a bi-amp set up.
I don't get any turn on or turn off thump--so far so good. I will listen all week to them run full range and then plug them into my line arrays when I feel that the testing has gone well.
The final measurements are:
Mono right (12.0volts rms output is arbitrary and set with my signal generator)
AC measured at 120hz negative speaker terminal 12.00volts
AC measured at 120hz positive speaker terminal 12.01votls
Relative DC offset between speaker terminals 20mv
Absolute DC offset between speaker terminals and ground-<100mv after one hour.
Mono left
AC measured at 120hz negative speaker terminal 12.00vots
AC measured at 120 hz positive speaker terminal 12.005mv
Relative DC offset between speaker terminals 60mv
Absolute DC offset between speaker terminals and ground <100mv after one hour
When adding the +/- signals on my scope I don't get a completly straight line and I suppose I could do better if I replaced the 840 ohm gain resistor with a pot and kept adjusting them until I got as close to a st. line as possible but I am not sure I could hear this difference.
I am sure that more tweaks will come later as new ideas come up in the threads.
Gl, My personal thanks for keeping me inspired and helping me understand the issues. Some day I will buy you a beer or even a good glass of wine. I am going to listen this week with the set up and report again when I have transioned back to the line arrays. My A75 is going on 15 years oldd without ever having a problem. I hope the AX 100 can have a similiar record. dave
To Gl -many thanks for the support and to Grey and Wuffwaff for your comments. I have finally listened to my AX100 conversion project -- wonderful.
My project goals
1. Find an amp to drive the 24 ribbon tweeters of my line arrays and mate sonically to my Pass 350.5's driving my mid bass drivers.
Crossover pt at 2.6k driving to 20k.
2. Revise the amp to get away from the 2kva mechanical transformer hum of my Aleph 1.2's.
3. Learn something new!
4. Have fun in the process and not have to reengineer a new chasis.
5. Sounds like real music based on the source material
I can say finally that items 1,3,4&5 have been very successful. Item 2 remains a work in progress, I get less mechanical noise from the new 1kva trannies than my Aleph 2kva trannies before but they are working really hard and are audible up close.
I finally listened to the amps run full range driving my 24 year lold Watkins WE-1's which present a very severe load in the bass with three 8" acoustic suspension drivers. The amps are harmoncially better than anything else I have heard; the Pass 350.5 driving the same speakers is a little better in the bass and takes less driving power from the preamp. The XA100 reveals how good the Aleph design really was. The XA 100 also for some reason makes the images more life like (including taller). I have to recalibrate my ears from 24 ribbon tweeters to two 1-1/4" audax but the Watkins are 53 inches tall and the image is another foot above that height. When listening to my line arrays which are estimated at 94db efficient vs the 85 to 87 db efficient Watkins: I normally sit 12 to 16 feet from the speakers. With the watkins I have to sit about 10 feet away for best sound.
The soundstage is first rate and the details on instrument location (depth and breath) on live recordings is first rate.
I haven't tried to use it yet on my line arrays and I have to recalibrate my ears based on the pt. source design of the Watkins but I am sure based on what I have heard that these amps will preform as good or better than my Pass/Tharagard A75 on the tweeters in my line array in a bi-amp set up.
I don't get any turn on or turn off thump--so far so good. I will listen all week to them run full range and then plug them into my line arrays when I feel that the testing has gone well.
The final measurements are:
Mono right (12.0volts rms output is arbitrary and set with my signal generator)
AC measured at 120hz negative speaker terminal 12.00volts
AC measured at 120hz positive speaker terminal 12.01votls
Relative DC offset between speaker terminals 20mv
Absolute DC offset between speaker terminals and ground-<100mv after one hour.
Mono left
AC measured at 120hz negative speaker terminal 12.00vots
AC measured at 120 hz positive speaker terminal 12.005mv
Relative DC offset between speaker terminals 60mv
Absolute DC offset between speaker terminals and ground <100mv after one hour
When adding the +/- signals on my scope I don't get a completly straight line and I suppose I could do better if I replaced the 840 ohm gain resistor with a pot and kept adjusting them until I got as close to a st. line as possible but I am not sure I could hear this difference.
I am sure that more tweaks will come later as new ideas come up in the threads.
Gl, My personal thanks for keeping me inspired and helping me understand the issues. Some day I will buy you a beer or even a good glass of wine. I am going to listen this week with the set up and report again when I have transioned back to the line arrays. My A75 is going on 15 years oldd without ever having a problem. I hope the AX 100 can have a similiar record. dave
Hi Dave,
Congratulations on the successful completion of your project. I can't tell you how relieved I am to hear how much you love the sound. I was more than bit worried that you might be disappointed since you had the X350.5 and Aleph 1.2 experiences right there as references.
For me it is enough that I helped someone else bring their project to a successful conclusion. It's just a small pay-it-forward thing for all of the help and inspiration that I've received here.
That being said I accept your offer of a beer. Perhaps you can come out to visit your son at Burning Amp time next year and you can both attend together(and bring beer).
It looks like your New Year is off to a very happy start. Enjoy!
Graeme
Congratulations on the successful completion of your project. I can't tell you how relieved I am to hear how much you love the sound. I was more than bit worried that you might be disappointed since you had the X350.5 and Aleph 1.2 experiences right there as references.
For me it is enough that I helped someone else bring their project to a successful conclusion. It's just a small pay-it-forward thing for all of the help and inspiration that I've received here.
That being said I accept your offer of a beer. Perhaps you can come out to visit your son at Burning Amp time next year and you can both attend together(and bring beer).
It looks like your New Year is off to a very happy start. Enjoy!
Graeme
aleph 1.2's to Ax100 testing 1st day
GL, all I have to do now is listen. I have some left over 2kva trannies at volts center tapped (+/-45vac) so maybe some day there will be an Aleph J project.
These could also be used by someone building the A75 and burnoff the extra voltage through a regulator.
As always things take longer to do right than originally planned and trouble shooting twists and turns take even more time.
After I listen to these for a few months I will probably think of something to change but for now I will just listen. Have you heard or seen NP's newest creations the xa100.5's? Who knows perhaps a quad Aleph O is next. dave
GL, all I have to do now is listen. I have some left over 2kva trannies at volts center tapped (+/-45vac) so maybe some day there will be an Aleph J project.
These could also be used by someone building the A75 and burnoff the extra voltage through a regulator.
As always things take longer to do right than originally planned and trouble shooting twists and turns take even more time.
After I listen to these for a few months I will probably think of something to change but for now I will just listen. Have you heard or seen NP's newest creations the xa100.5's? Who knows perhaps a quad Aleph O is next. dave
Hi Dave,
Its nice to read about your project ..well done!
Graeme,
I have nearly completed my X Aleph based on your schematic and fired it up on the main system tonight. See other thread soon.
My impressions are much like Dave's.
Very smooth and lush midrange with a presentation that draws you into the music.
Without your support many of us X Aleph builders would not be where we are today.
Ian
Its nice to read about your project ..well done!
Graeme,
I have nearly completed my X Aleph based on your schematic and fired it up on the main system tonight. See other thread soon.
My impressions are much like Dave's.
Very smooth and lush midrange with a presentation that draws you into the music.
Without your support many of us X Aleph builders would not be where we are today.
Ian
aleph1.2 to AX100
Gl, I got the AX120's now hooked up to my line arrays as the tweeter amps driving the speakers from 2600hz to 20k with a 48db/octave crossover.
When comparing the sound of my A75 vs the AX120 in this application all I can say is the AX gives the better spatial presentation regarding recorede echo effects or live recording venues.
When using the AX120 vs A75 Vs the Pass 350.5 on my older Watkins speakers run full range the A75 and 350.5 have a touch better bass driving acoustic suspension woofers (three per speaker at 100hz and down).
However they sound much like the Aleph's in giving a big soundstage and add a touch of warmth to all those ribbon drivers on my line arrays. The project has been a huge acoustic success an I am very happy.
One issue I still have is what to do about noisy trannies. Late at night with the heat turned down I still get a faint mechanical background hum at the listening position. there is no electrical noise what so ever from the speakers even with my ear at the drivers.
Have you ever tried doubling the trannies to get quieter sound? I have to think of something, I called Plitron and Avel Lindberg and to buy quiet trannies is 4 times the cost and neither will guareentee quiet products.
This is an issue just for me and may not be an issue for anyone else. It might be interesting to know where NP gets his production trannies because my 350.5 is dead quiet.
I am sure this is due to the heavy currents that the torroids are subject to. Mine are 1kva avel - lindbergs out of their standard catalog and are made in china. dave
Gl, I got the AX120's now hooked up to my line arrays as the tweeter amps driving the speakers from 2600hz to 20k with a 48db/octave crossover.
When comparing the sound of my A75 vs the AX120 in this application all I can say is the AX gives the better spatial presentation regarding recorede echo effects or live recording venues.
When using the AX120 vs A75 Vs the Pass 350.5 on my older Watkins speakers run full range the A75 and 350.5 have a touch better bass driving acoustic suspension woofers (three per speaker at 100hz and down).
However they sound much like the Aleph's in giving a big soundstage and add a touch of warmth to all those ribbon drivers on my line arrays. The project has been a huge acoustic success an I am very happy.
One issue I still have is what to do about noisy trannies. Late at night with the heat turned down I still get a faint mechanical background hum at the listening position. there is no electrical noise what so ever from the speakers even with my ear at the drivers.
Have you ever tried doubling the trannies to get quieter sound? I have to think of something, I called Plitron and Avel Lindberg and to buy quiet trannies is 4 times the cost and neither will guareentee quiet products.
This is an issue just for me and may not be an issue for anyone else. It might be interesting to know where NP gets his production trannies because my 350.5 is dead quiet.
I am sure this is due to the heavy currents that the torroids are subject to. Mine are 1kva avel - lindbergs out of their standard catalog and are made in china. dave
Dave,
I think you can address the noise issue on several fronts:
1. The buzz (as opposed the fading hum) is the windings.
A. One way to deal with this is over-rate the transformer. It has been suggested 7 x the class A output power. In this respect I would go for 5 x the power consumption. ie 300 watts dissipation use 1500 va.
ie If the transfomer is not under a heavy load it is less likley to have windings buzz .
B. Use a sorbathane pad under the transformer.
C. Encase or pot the transform in suitable epoxy.
2. The recurring or fading hum or drone.
This can be for avariety of reasons
A. I have found getting the transformer maker to wind on the next core size up makes a big improvement to the transformer flux saturation (what causes the drone) and being susceptible to mains borne noise.
ie 500 va use 625 va core.
B. Use seperate rectifiers for each secondary winding
C. Use a CD blocking circuit.
I have used examples of 2 A and it seems . Next time I will also adopt 1A.
macka
I think you can address the noise issue on several fronts:
1. The buzz (as opposed the fading hum) is the windings.
A. One way to deal with this is over-rate the transformer. It has been suggested 7 x the class A output power. In this respect I would go for 5 x the power consumption. ie 300 watts dissipation use 1500 va.
ie If the transfomer is not under a heavy load it is less likley to have windings buzz .
B. Use a sorbathane pad under the transformer.
C. Encase or pot the transform in suitable epoxy.
2. The recurring or fading hum or drone.
This can be for avariety of reasons
A. I have found getting the transformer maker to wind on the next core size up makes a big improvement to the transformer flux saturation (what causes the drone) and being susceptible to mains borne noise.
ie 500 va use 625 va core.
B. Use seperate rectifiers for each secondary winding
C. Use a CD blocking circuit.
I have used examples of 2 A and it seems . Next time I will also adopt 1A.
macka
Hi Macka,
try these guys, nice transformers and good prices
http://www.users.bigpond.com/harbuch/default.htm
I used them for my aleph 2s and no probs at all.
cheers arthur
BTW I used a 1kva for each 300 watt monoblock.
try these guys, nice transformers and good prices
http://www.users.bigpond.com/harbuch/default.htm
I used them for my aleph 2s and no probs at all.
cheers arthur
BTW I used a 1kva for each 300 watt monoblock.
aleph1.2 to AX100
Guys thanks for the advice, I have installed a dc blocking and ac noise reduction circuit on the primary side of the trannies.
I will begin trying as time allows the other suggestions. The trannies don't seem to run too hot (my heatsinks do but within tolerance) and I will try doubling the trannies and see where that takes me.
However, my motivation is getting weak as the amps sound so good and it is hard to mess with a good thing.
It is interesting to note that I am using a 800va trannie in my A75 which is almost twice the recommended size and there is absolutely no noise at all. More to come and again thanks, dave
Guys thanks for the advice, I have installed a dc blocking and ac noise reduction circuit on the primary side of the trannies.
I will begin trying as time allows the other suggestions. The trannies don't seem to run too hot (my heatsinks do but within tolerance) and I will try doubling the trannies and see where that takes me.
However, my motivation is getting weak as the amps sound so good and it is hard to mess with a good thing.
It is interesting to note that I am using a 800va trannie in my A75 which is almost twice the recommended size and there is absolutely no noise at all. More to come and again thanks, dave
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