Aleph Jzm

[6L6]

This absolutely isn't clutter.

This is why the forum exists.

 

[audionut]

So I finished my low power Aleph JZM...Using Zen Mod's suggestion, replaced R28, R29 with 0R56/3W and removed R30.

Rails are plus and minus 15.4v. Each rail is drawing 1 amp. Under resistive load of 6.5 ohms the Aleph JZM clips at 7v with current through the load of 1.1amp. Input signal of .9v.

These measurements taken with DMM. I could see the clipping on my 0-scope, but don't trust it for measurement.

Can I infer that Aleph JZM is seven or so watts of power. Not sure how to calculate output power.

Do these measurements seem fine?

Can I build two channels into the Amp Camp chassis...is there enough heat sink capacity?? I would use Mean Well SMPS supplies outboard.

Thanks in advance for anybodies answer...

 

[ItsAllInMyHead]

^ It's important to use units, but I'll try to make a guess. Never assume my math and phrasing are accurate or that my knowledge is complete. 🙂

the Aleph JZM clips at 7v with current through the load of 1.1amp. Input signal of .9v.

Given that the rails are 15V4 (not sure where you measured), the load is 6R5, and the current through the load is 1A1...

Assume ~4V loss through output devices => 11.4V peak => ~8Vrms would be the rough estimated voltage clipping into any load. As an example, you'd "hit the rails" into a 16 ohm load before you'd run out of current.

1A1 and 6R5 load => 7V1rms for running out of current. So, that roughly works out.

These measurements taken with DMM. I could see the clipping on my 0-scope, but don't trust it for measurement.

You can't see clipping on a typical DMM, so how do you know when it clipped? Why don't you trust your scope? Between a typical hand-held DMM and even the cheapest of scopes, I'd prefer to use the scope to see when the signal clips.

Each rail is drawing 1 amp.

Each rail?

Can I infer that Aleph JZM is seven or so watts of power.

Into what load? For the 6R5 load, assuming your measurements are correct, that's close enough. By my math, it's close to 8W. I wouldn't split hairs.

Not sure how to calculate output power.

Ohm's Law.

 

[6L6]

Can I build two channels into the Amp Camp chassis...is there enough heat sink capacity?? I would use Mean Well SMPS supplies outboard.

if you don't mind the heatsinks running very, very hot, I suppose yes, you could. There may be physical space limitations however.

 

[audionut]

Thanks for your replies...The scope isn't calibrated, voltage readings off the scope don't seem right...Probably not reading right. Guess I will have to look at the manual. Rigol DS1102e. But I see a nice 1000hz sign wave on the loaded output. Clip is just a flattening of the tops and bottoms of the wave. Measuring each rail...plus to ground and minus to ground I get 15.4 volts per rail or around 30v across the plus and minus rail...your explanation helps me a lot in understanding how the amp works. I measured current on each rail individually and observed roughly 1 amp of current per side.

Would the Amp Camp chassis have enough heat sink capacity for two channels of the above? My measurements are taken with the mosfets on small heat sinks. I don't leave the circuit on for long...

 

[Zen Mod]

The scope isn't calibrated, voltage readings off the scope don't seem right

that's easy with integrated square gen , though then you need to think in Vpp and convert to Vrms with calc

anyhow, for job at hands no need for cal. work, use scope to see clipping and use DVM to measure Vrms directly, but be aware of fact that measurement is OK all the way to clipping, while in clipping just ignore measurement figure

now, calc dissipation you have ( sum rails * Iq), compare that to ACA dissipation figure, and you'll know is it feasible to squeeze it in ACA case

 

[lewjanki]

Hey, new member here! First of all, thanks to everyone involved for developing, providing the resources to the community and then also helping and answering questions. Really amazes me.
Now, of course I am not only posting out of gratitude, I also have a question🙂
How exactly would it be possible to use one of the mmbfj270/271 ics? Is there someone who has experience how to mount/cool them properly. I am aware about the existence of the adapters and I was thinking about building one myself, but how effective are they in terms of heat transfer to the radiator?
Would it be sensible to parallel more than two mmbfj270/271? Considering their price, I could just order 100 pieces from digikey for 25€ and choose for example 8 or 10 per chanel. Is there something I am missing?

 

[Zen Mod]

if you take kit from Store, you get TO92 J271, matched, easy to solder

one day in future, if IAIMH resort to mmbfj, they'll be soldered to pcbs you get

 

[lewjanki]

I wanted to do the layout myself anyways, so just was wondering how you would archieve a low heat transfer coefficient between the ic and the aluminum. As far as I am aware of, the most (around 90%) heat is coming out from the very small footprint towards the pcb, so a lot of copper area + vias would be required. So just to reiterate, would it be possible, without major changes in the result, to parallel more than two transistors in this design?

 

[Zen Mod]

I wanted to do the layout myself

if you're really able to do layout by yourself, then you're able to reply to your own questions ( asked here) so , factually - no need to ask them

now - either buy kit from Store and build it, or invest some more time (personal or with help) to gain really composite knowledge to do it properly

now, making own pcbs from someone else's schematic is , well, really back end of the Story

zillion of necessary basic things goes before that, and without those - it's really hard to make proper pcb

so, moral of the Story - I'm not heading you to spill your money in the Store, just saying that making pcbs for fun - without preceding knowledge, is really no more than headless backdoor jumble

 

[kotofei]

Finished my Aleph Jzm built few days ago. Listening to her each day and would like to share my first impressions.

SOUND:

First, it’s a FET amp i.e. one with clear and crisp high frequencies; I use to have a Kyocera R-761 with the kind of similar sound signature. However, Kyocera had upper midrange and highs more pronounced to the point that it sounded unnatural with the associated listening fatigue. Aleph Jzm is way more balanced in this regard and I didn’t get any listening fatigue with her. I have a feeling the sound in natural with no particular frequency group is elevated.

Second, Aleph excels in reproduction of human voices: I have an impression that singer(s) are just in from of me and in front of other instruments. Voices are very natural, too. No power amp or integrated I have had reproduced human voices better than Aleph. This is “quantum leap #1”.

Third, the overall reproduction of instruments’ sound is the best I have had: instruments sound close to the “live” ones. Piano sounds almost like the live piano with Aleph; however, the biggest improvement which I consider “quantum leap #2” is with cymbals. I have never heard them as natural as with Aleph Jzm on different recordings. Wondering is it that “Liquid midrange” tube amps are praised for? Regardless, I LIKE this A LOT.

Fourth, the instruments at the soundstage are very well defined and are not overlapping each other. I can even hear some backstage instruments on familiar records that have not been heard before. The soundstage itself is wide and tall i.e. some instruments (mostly cymbals) are heard above speakers.

Last but not the least- the amp is dead silent.

The build guide and hardware:

The build guide was very well written, illustrated and organized. I read it couple of times before starting and tried to follow by the letter. Used rhthatcher power supply; here, I had a few questions but they were quickly answered in this thread. Assembly was easy and straightforward after I solved the (small) problem of positioning power supply components on the chassis. At the end I was quite surprised that no major disaster(s) happened right away since this my first big audio assembly project.

Few little things could be improved IMHO:

• The power switch. It is located at a very inconvenient position in the middle of the back panel and I think alternative ways of powering up the Aleph should be mentioned in the assembly guide. I started this thread on the subject and it turns out this was addressed before: there are remotely-controlled power outlets (I got one off Amazon) and a whole remote switch assembly with the PCB is available. I might go this route in the future…
• The chassis could be improved a little: holes for LEDs at the front panel are too small to insert them so in my case I just glued the LEDs with the tape over the holes and the light is very dim outside. Also, it could be a good idea to make a deepening inside the lower right or left of the faceplate that could be extended to the full-size hole for those who would like to use the front panel switch. In addition, my chassis had many pieces of hardware turns out unnecessary bit did not have some which were required such as long M3 bolts to attach legs at the bottom.

But these are minor things.

Overall, I am very happy- I have never had a power amp as good as Aleph Jzm.

Thanks to all DIYaudio community members for answering questions and special thanks to ItsAllInMyHead, rhthatcher, Zen Mod and Nelson Pass!

 

[Jacruzer787]

Zm is on a roll today….

 

[lewjanki]

if you're really able to do layout by yourself, then you're able to reply to your own questions ( asked here) so , factually - no need to ask them

I agree, my question was silly. I should have checked the schematics and your guide first - heat shouldn't be a problem on the jfets obviously, just judging by the calculated maximum possibile power dissipated at them.

now - either buy kit from Store and build it, or invest some more time (personal or with help) to gain really composite knowledge to do it properly

zillion of necessary basic things goes before that, and without those - it's really hard to make proper pcb

Now, I don't see how being highly knowledgeable in analog design is a necessity for layouting. Coming from designing and layouting digital electronics with the associated difficulties, I don't see a problem transfering that to an analog board, giving there is a schematic already available. The layouting obviously forces one to make oneself aquatinted with the schematic and as a firm believer of learning by doing I thought that would be the way for me.

now, making own pcbs from someone else's schematic is , well, really back end of the Story

I wasn't aware if that, I'm not really initiated into the electronics etiquette. By the fact, that most if the designs sold are based on Nelson Passes developments, I was assuming that it would be ok to also cooy paste them into my own layout.

 

[Zen Mod]

Coming from designing and layouting digital electronics with the associated difficulties

what I wrote stays in previous context, but you didn't said that before

now, if you know what proper pcb routing means, in any other realm than audio, you're good to go

 

[ItsAllInMyHead]

Finished my Aleph Jzm built few days ago. Listening to her each day and would like to share my first impressions.

Congratulations!

SOUND:

I LIKE this A LOT.

Wonderful! As is often said around here, "Everyone needs an Aleph". 🙂

Last but not the least- the amp is dead silent.

Excellent, but hopefully only with no signal.

The build guide and hardware:

The build guide was very well written, illustrated and organized. I read it couple of times before starting and tried to follow by the letter.

Thank you. It was my first attempt at a guide, so I tried to create it from the viewpoint of my first amp project. Emphasis added is mine, but that's my best advice. Suggestions are always welcome.

Used rhthatcher power supply; here, I had a few questions but they were quickly answered in this thread. Assembly was easy and straightforward after I solved the (small) problem of positioning power supply components on the chassis.

Layout / wiring seems to be one of the toughest things to overcome for first builds. There are so many options. We can perhaps add a few more examples from existing builds to show more examples.

At the end I was quite surprised that no major disaster(s) happened right away since this my first big audio assembly project.

You read and re-read before building. Yours is an excellent example that if you follow the instructions, there should be no major mishaps.

Few little things could be improved IMHO:

• The power switch. It is located at a very inconvenient position in the middle of the back panel and I think alternative ways of powering up the Aleph should be mentioned in the assembly guide. I started this thread on the subject and it turns out this was addressed before: there are remotely-controlled power outlets (I got one off Amazon) and a whole remote switch assembly with the PCB is available. I might go this route in the future…

That's always tricky. You may be surprised at how challenging it is to find a good-looking (subjective certainly) properly rated, non-gazillion dollar front panel switch. That's separate from using yet another piece of kit the user would need to build like Mark Johnson's H9KPXG. Your solution is fantastic. There may be some more user-friendly front-panel options ... soon... .

• The chassis could be improved a little: holes for LEDs at the front panel are too small to insert them

Those are just pilot holes. You'd definitely need to enlarge them to the common 3mm or 5mm size if you want. Some folks also like them at varying depths or even use light pipes. The pilot holes require some additional work, but they also allow some flexibility.

• so in my case I just glued the LEDs with the tape over the holes and the light is very dim outside. Also, it could be a good idea to make a deepening inside the lower right or left of the faceplate that could be extended to the full-size hole for those who would like to use the front panel switch. In addition, my chassis had many pieces of hardware turns out unnecessary bit did not have some which were required such as long M3 bolts to attach legs at the bottom.

But these are minor things.

Noted and appreciated. These kits are for you ... so we listen to see what we can do to make them easier / more accessible to more people (within reason).

Overall, I am very happy- I have never had a power amp as good as Aleph Jzm.

Woo hoo! The AJ is a pretty special amp (in all its forms).

 

[audionut]

Finished one JZM Channel. Powering it with two Meanwell 15v power supplies.

Lets say I wanted to build an analog power supply with 15v rails. What size transformer should I get. Right now, one channel draws one amp per rail. So two channels would draw 2 amps per rail. I think a 12-12v transformer would get 15v rails under load...but how big should it be...what VA?

thanks

 

[Zen Mod]

twice 15 then 1A gives you 30W of heat

channels two, means 60W

no less than 200VA xformer for that, if you want 15Vdc, yeah, 12Vac secs are good

 

[audionut]

great...thanks

 

[audionut]

The reason I am thinking about an anolog supply for the JZM, is because I originally powered the circuit with an Aleph analog supply that I turned down to 15v per rail with one of those GE variable transformers. Putting a 7 ohm dc load on the circuit and looking at a 1000 hz wave form on my O-scope, I saw a nice smooth wave form all the way to clipping.

Powering the circuit with two Meanwell 15v supplies, and looking at the 1000hz wave form under load, the tops and bottoms of the wave were spikey looking. Circuit was not near clipping...

Would that be the SMPS supply doing that? and could this be why we don't like SMPS power supplies for power amplifiers?

I haven't listened to the JZM yet...

Thanks

 

[Zen Mod]

saw a nice smooth wave form all the way to clipping...................

...........spikey looking..............


Would that be the SMPS supply doing that?

if they're Drek enough, yes

anyhow, even if you have smps feeding da amp, you still need decent cap bank as final PSU element, hoping that used smps allows decent cap afterwards