150 VA donut per channel sounds like a decent choice to me.
Anybody built monoblocs with those with one zink per fet, board in the middle? Pics?
bloody vikings, hairsplitting 50VA........
clarify second sentence, what's idea?
small monoblock?
clarify second sentence, what's idea?
small monoblock?
I’m scared of monsters. And I like to be able to mix and match amps for active filter per channel. Amps are local, by spkrs
Soooo
Finally had a chance to work on this.
I rebuilt the Snubber boards with all new parts. Had a set of rectifiers and new snubbers that I'd purchased from Randy a little while ago for an attempt at an F4. The new rectifiers have the plastic bodies.
I drilled out the hole with a step bit to allow for the washers to pass through the PCBs and made sure to solder the AC posts this time. Replaced the Thermistor (again just in case) and removed the entire power supply to inspect. Nothing seems amiss, except that the thermistor traces are getting pretty mungled due to all of the soldering/desoldering. Checked for continuity with the chassis ground. Seems to be fine.
Turned on the newly fitted power supply and got +/- 24V as expected (same as before) after bringing it up on the variac. So far so good.
Plugged the audio channels back in and no bueno. Still getting a loud buzz through both speakers.
Not sure where to go from here. Seems like this amp (or power supply) is toast. My troubleshooting skills are pretty rudimentary (as you can probably tell).
Does the smoke stay in? What does the power supply measure under load (one or both amp boards connected)? Did you hook up one channel at first to test, then the other? How does it behave with only one channel connected? And the other one solo?
@SeeRockCity
A hum/buzz does not mean your PCBs are not right. Wiring, impedance mismatch, and possible dirty AC are often culprits, among others. Chasing a hum is no fun, but it will be silent with diligent effort. Can you be sure it's the amp? What happens if you just have amp powered on with speakers connected and the inputs shorted? Did you set the jumper properly for SE vs balanced options on the PCB? I think posting lots of well lit pics will get the "hive of minds" to help you out. In doing so, you'll also be helping others.
Experts much smarter than I await lots of clear, well lit photos of your amp.
For me, as an example, my dimmable home ceiling LED lights were causing the hum (well not the lights, but the "smart" dimmer). If I set LED lights to middle brightness, hums everywhere. If I set brightness to lower end, or higher end, of dimmer, hum goes away. Just one example, but sharing that finding the cause is not always the build itself. I could hear the hum with no speakers connected in my Aleph Jzm. The transformer itself was humming when the lights were on. It took me 3 days of effort to figure that out. I was perplexed before I tried shutting off my home C/B one by one until the hum disappeared....sure enough, the LED light circuit was the issue. LED dimmable lights off, no hum, flip the breaker back on....hum returned. I lucked out that simply turning them to a setting outside 40-60% brightness range also got rid of hum. So now my living room is either really dark, or really bright. Wife doesn't understand my logic, but I am happy, music is hum free, and we all can still see 😊
You can measure the frequency of the hum using a phone app, such as "spectroid".
Also, read the PDFs here....good info on ground loops. I'm still re-reading the well put together document to understand it all.
I can assure you that your not the only one dealing with hum. I just spent yesterday morning chasing hum in my Iron Pumpkin. Turns out, if I have balanced connections, but select a SE input, I get hum. If I use SE connections and select a balanced input option I get hum. But using the proper selection to match the connections, no hum. So, I identified the issue and it's an easy "fix". I'm happy sitting with dead silent preamp now. I knew it wasn't the amp, as if I didn't connect the amp to anything, dead silent. Also of note, I only heard the hum when on max volume, so Iron Pumpkin is pretty darn quiet even when I've mismatched input selection and connections.
A hum/buzz does not mean your PCBs are not right. Wiring, impedance mismatch, and possible dirty AC are often culprits, among others. Chasing a hum is no fun, but it will be silent with diligent effort. Can you be sure it's the amp? What happens if you just have amp powered on with speakers connected and the inputs shorted? Did you set the jumper properly for SE vs balanced options on the PCB? I think posting lots of well lit pics will get the "hive of minds" to help you out. In doing so, you'll also be helping others.
Experts much smarter than I await lots of clear, well lit photos of your amp.
For me, as an example, my dimmable home ceiling LED lights were causing the hum (well not the lights, but the "smart" dimmer). If I set LED lights to middle brightness, hums everywhere. If I set brightness to lower end, or higher end, of dimmer, hum goes away. Just one example, but sharing that finding the cause is not always the build itself. I could hear the hum with no speakers connected in my Aleph Jzm. The transformer itself was humming when the lights were on. It took me 3 days of effort to figure that out. I was perplexed before I tried shutting off my home C/B one by one until the hum disappeared....sure enough, the LED light circuit was the issue. LED dimmable lights off, no hum, flip the breaker back on....hum returned. I lucked out that simply turning them to a setting outside 40-60% brightness range also got rid of hum. So now my living room is either really dark, or really bright. Wife doesn't understand my logic, but I am happy, music is hum free, and we all can still see 😊
You can measure the frequency of the hum using a phone app, such as "spectroid".
Also, read the PDFs here....good info on ground loops. I'm still re-reading the well put together document to understand it all.
I can assure you that your not the only one dealing with hum. I just spent yesterday morning chasing hum in my Iron Pumpkin. Turns out, if I have balanced connections, but select a SE input, I get hum. If I use SE connections and select a balanced input option I get hum. But using the proper selection to match the connections, no hum. So, I identified the issue and it's an easy "fix". I'm happy sitting with dead silent preamp now. I knew it wasn't the amp, as if I didn't connect the amp to anything, dead silent. Also of note, I only heard the hum when on max volume, so Iron Pumpkin is pretty darn quiet even when I've mismatched input selection and connections.
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Just finished a low voltage Aleph JZM, and listened to it.
I first built the Amp Camp Mini for a bi amped bedroom system. It was all right, but I have always liked my Aleph J's. So I built a low voltatge Aleph JZM. My thanks to Zen Mod for his help on certain things.
I built the low voltage JZM into an Amp Camp chassis, using Meanwell power supplies. Rails are 15v. Current draw is around 1 amp per rail per channel. Clips at around 7v rms. Heat Sinks around 45c. Volts over r28 at .620. ( At 15v rails, Zen Mod recommended replacing some of the .27 ohm resistors with .58 ohm.s to keep bias current in line)
The JZM is in a biamped system...one channel for tweeter, one channel for woofer. I prefer the JZM to the Amp Camp Mini...Maybe those electrolytic capacitors in the output of the Amp Camp Mini get in the way.
Anyway, I think the JZM a nice improvement...I am back to that nice warm Aleph J sound..Plenty of base, Tweeter sounds much better, less hashy. For what is a 7 watt amp, surprising amount of volume. (bi-amping does that) So thanks to Papa and Zen Mod...
The Amp Camp Chassis is a very sharp looking case...
I first built the Amp Camp Mini for a bi amped bedroom system. It was all right, but I have always liked my Aleph J's. So I built a low voltatge Aleph JZM. My thanks to Zen Mod for his help on certain things.
I built the low voltage JZM into an Amp Camp chassis, using Meanwell power supplies. Rails are 15v. Current draw is around 1 amp per rail per channel. Clips at around 7v rms. Heat Sinks around 45c. Volts over r28 at .620. ( At 15v rails, Zen Mod recommended replacing some of the .27 ohm resistors with .58 ohm.s to keep bias current in line)
The JZM is in a biamped system...one channel for tweeter, one channel for woofer. I prefer the JZM to the Amp Camp Mini...Maybe those electrolytic capacitors in the output of the Amp Camp Mini get in the way.
Anyway, I think the JZM a nice improvement...I am back to that nice warm Aleph J sound..Plenty of base, Tweeter sounds much better, less hashy. For what is a 7 watt amp, surprising amount of volume. (bi-amping does that) So thanks to Papa and Zen Mod...
The Amp Camp Chassis is a very sharp looking case...
Last weekend I managed to finish my Aleph JZM.
The proces was fairly straight forward, thanks to the great build guide. Sometimes a search for the right info, as there are quite a few ways to build the power supply for example. Mounting the transformer took me the longest (too many choices), but in the end I printed a mount designed by Birdbox in PETG and used a L-bracket. Also printed 2 cable-towers by his design.
As mildly suggested by ZenMod, I added a speaker protection circuit. This caused some wiring complications, but in the end it al works.
I used a 400VA audiophile (potted) Toroidy transformer (took 9 weeks to arrive from Poland to the Netherlands), 47000uF capacitors on rthatchers PSU board. Microphone wire for the inputs, silicon coated for speaker connections and power.
As I had none, no variac or dim bulb tester was used during initial powerup (living dangerously, but took me a day to work up enough courage). The PSU was tested first, after that one amp board at a time. Luckily, no magic smoke, all seems stable, bias was stable after an hour or two (cold room). In my 4U the heat dissipation blocks do not get very warm, can easily touch them.
Biasing went well, I plan to check again when the feet I ordered will arrive (chinese newyear delay). Right now standing on the standard feet. Bias @ 460mV, speaker offset around 1mV.
It is dead silent in use with my OmegaTwelve speakers (stated to have an efficiency of around 100dB/W). It sounds wonderful, strong and controlled bass, detailed, non-fatiguing, musical, precise and generous soundstage. I used an Elekit TU-8800 before (with KT88 and Lundahl transformers) and that was great, but think the JZM will stay.
Thanks to all the great people who made this project possible! I'm very grateful to you all and couldn't have done it without your considerable effort in making this project!
I have included some pictures, did not make many building it.
Transformer mount
The proces was fairly straight forward, thanks to the great build guide. Sometimes a search for the right info, as there are quite a few ways to build the power supply for example. Mounting the transformer took me the longest (too many choices), but in the end I printed a mount designed by Birdbox in PETG and used a L-bracket. Also printed 2 cable-towers by his design.
As mildly suggested by ZenMod, I added a speaker protection circuit. This caused some wiring complications, but in the end it al works.
I used a 400VA audiophile (potted) Toroidy transformer (took 9 weeks to arrive from Poland to the Netherlands), 47000uF capacitors on rthatchers PSU board. Microphone wire for the inputs, silicon coated for speaker connections and power.
As I had none, no variac or dim bulb tester was used during initial powerup (living dangerously, but took me a day to work up enough courage). The PSU was tested first, after that one amp board at a time. Luckily, no magic smoke, all seems stable, bias was stable after an hour or two (cold room). In my 4U the heat dissipation blocks do not get very warm, can easily touch them.
Biasing went well, I plan to check again when the feet I ordered will arrive (chinese newyear delay). Right now standing on the standard feet. Bias @ 460mV, speaker offset around 1mV.
It is dead silent in use with my OmegaTwelve speakers (stated to have an efficiency of around 100dB/W). It sounds wonderful, strong and controlled bass, detailed, non-fatiguing, musical, precise and generous soundstage. I used an Elekit TU-8800 before (with KT88 and Lundahl transformers) and that was great, but think the JZM will stay.
Thanks to all the great people who made this project possible! I'm very grateful to you all and couldn't have done it without your considerable effort in making this project!
I have included some pictures, did not make many building it.
Transformer mount
now build another one, as dual mono, and you'll get Fugly!
every proper Musiclover home ought to have even number of Papaalephs
Nice work @RobertF !!! Beautiful looking build!
PETG and PLA are not the ideal materials for the transformer seat, but the way you implemented it with an "L-bracket" certainly does provide some rigidity to the mount.
My posted designs for the transformer seats are based on Antek dimensions, but if anyone wants a version that is custom fit for their transformer (such as Toroidy), please PM me with the dimensions and I will make up a custom print file that fits your toroid transformer snuggly. I'm happy to post those designs freely for anyone to use.
Side note: Those wires posts are handy dandy and I'm glad to see you tried them out. I use them for all of my builds now to maintain wire separation and guidance. They work really well in my opinion and are affordable to make for what they do (4 posts for under $1).
Enjoy that Aleph Jzm!!! Wonderful amp!
PETG and PLA are not the ideal materials for the transformer seat, but the way you implemented it with an "L-bracket" certainly does provide some rigidity to the mount.
My posted designs for the transformer seats are based on Antek dimensions, but if anyone wants a version that is custom fit for their transformer (such as Toroidy), please PM me with the dimensions and I will make up a custom print file that fits your toroid transformer snuggly. I'm happy to post those designs freely for anyone to use.
Side note: Those wires posts are handy dandy and I'm glad to see you tried them out. I use them for all of my builds now to maintain wire separation and guidance. They work really well in my opinion and are affordable to make for what they do (4 posts for under $1).
Enjoy that Aleph Jzm!!! Wonderful amp!
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I have an output transformer-coupled tube preamp. My understanding is that this means no possible DC offset at its outputs. So am I safe in bypassing C1 on my Aleph Jzm ?
Hi my aleph j Zen mod build is going not so great i put together everything but apparently i must have something wrong as i cant manage to get a click pop or anything at all to tell me im getting power to the unit i think i have the power supply connected correctly but i get no power when plugging it in