Aleph J illustrated build guide

[andynor]

Hi guys, i'm working on this Amp and actually i'm building it as reported in the blogspot guide: https://diyalephj.blogspot.com/

I'm planning to use it with my .FLAC audio library and i've two main doubts about DAC and/or preamplifier: You guys have some recommendations about which USB DAC (with balanced XLR output) i can buy and use with this amplifier?

Also, using a good quality DAC, it's necessary to also add a preamplifier?

BTW, Sorry for the dumb questions!

No dumb questions.

Consider one of the reasonably priced Topping or SMSLs, then listen and decide whether you need a preamp. The J has a very high input impedance, making it easy to drive. However, with a very good DAC - though with opamps in the OS, I found the J to sound significantly better with a preamp/buffer+VC. If you don’t need preamp gain to drive your speakers, the B1 or B1 R2 (check threads) are cheap, very good and simple alternatives, but of course to go balanced you need to do a bit more work

 

[near_field_obj]

Have a look at the topping E50, it is balanced, costs a bit less but does not have Bluetooth. I am interested in making a Logitech Music Server and was looking for a balanced dac with coax input.

Nice DAC and impressive performances at this price, it can be connected to AMP using this adapter: https://www.mouser.it/ProductDetail/568-NA2MPMM-W

This is nice, also, it will remove the "need" to add preamplifier in front of Aleph J.

 

[near_field_obj]

No dumb questions.

Consider one of the reasonably priced Topping or SMSLs, then listen and decide whether you need a preamp. The J has a very high input impedance, making it easy to drive. However, with a very good DAC - though with opamps in the OS, I found the J to sound significantly better with a preamp/buffer+VC. If you don’t need preamp gain to drive your speakers, the B1 or B1 R2 (check threads) are cheap, very good and simple alternatives, but of course to go balanced you need to do a bit more work

Thank you, i'm looking (as suggested) to the TOPPING E50, it seems a good balance about price and performances, also has balanced outputs!

Maybe it will be a good way to go...

 

[ElliJ]

What I liked about the E50 was the auto on/off, bal and se outputs and also optical, coax and usb inputs.
I was looking for a dac with just a coax input and a balanced line out (no volume) to plug into a preamp (iron pre when I make it). A RaspberryPi with LMS, picoreplayer and a spdif hat to be used as a digital source (music and radio). I could not find such a simple dac.

 

[wdecho]

Forgive my ignorance but looking at this circuit am I seeing a quasi complementary output stage? That and which parts make the aleph CCS? Just trying to understand the circuit better.

 

[Zen Mod]

Aleph CCS is upper part, modulated Current Source, so acting both as biasing mechanismus and also as upper part of PP OS, where you can set desired amount of its contribution in output

look here:

 

[wdecho]

Aleph CCS is upper part, modulated Current Source, so acting both as biasing mechanismus and also as upper part of PP OS, where you can set desired amount of its contribution in output

look here:

You are saying PP which was my thoughts at first when seeing the circuit but on the Firstwatt page it is described as a SE.

 

[andynor]

You are saying PP which was my thoughts at first when seeing the circuit but on the Firstwatt page it is described as a SE.

It is acting like a part of a PP OS. Not making it a PP circuit. Still only a CCS, but increasing efficiency and stability into low impedances, etc. many advantages. It could be replaced with a resistor, making it hopelessly inefficient, less powerful, but perhaps even more true to the single ended topology.

Addition: If you reduce the CCS controbution as mighty sez, you get more 2hd and even more SE romance and sugar, but also less power and perhaps a little less stability into difficult loads, etc. the wonder of the Aleph CCS is it enables people to keep the qualities of SE topology even with more demanding speaker loads, and with more power than most SE circuits, using a CCS applying minimal damage to the SE spirit

 

[Zen Mod]

study the patent and whatever schematic you can find of it

you'll see that behavior is different to regular PP stage, even when Aleph CCS is set to 50% contribution

(one of the) catch(es) is that Aleph CCS behavior/modulation is strongly dependent of load (speaker) itself

 

[wdecho]

If I understand correctly what you guys are saying Q5 and Q6 along with other components make up the CCS and Q7 and Q8 make up the amplification part of the design. If so I understand the circuit better now. Thanks

 

[Extreme_Boky]

I was in the same place as you are. The main trigger for asking questions, in my case, was the inclusion of the R20 thru R23 in the design... which is a downside (but unavoidable) of this active current source implementation that brings lower distortions and better efficiency.

Check the patent paper attached.

 

[bwater]

Just a thanks to Extreme_Boky - my Aleph J was humming (not in a good way). Curse the new speakers. So, after a quick search through threads and downloading Spectroid on my phone: hum is 120Hz. Tried your ground lift resistor, and I heard... nothing. Dead quiet. Beautiful. Thanks for posting the info.

 

[Extreme_Boky]

I'm glad you got it sorted. Well done.

 

[Dr Greenthumb]

I've been enjoying this amp for a few months now and have really been enjoying it. One thing I have been wondering about is the bottom end and why it is so soft. The bass is just isn't tight. I am trying to push Altec Lansing 604s at 16 ohms. This amp does well with these speakers, just not down low. Thinking there might be something going on with 604s, I hooked up a pair of McIntosh MC-30s. The lows are there, nice and tight.

Is there anything I can do to get nice performance down low?

 

[Zen Mod]

put 1KHz sine, 1W at output, through dummy load (8R)

measure voltage AC across source resistor in lower rail, write down
measure voltage across AC resistor in upper rail, write down

inform here

goal is to find what Aleph CCS AC gain you have actually

meaning - when said is approx 50%, that means that upper half of amp OS ( exactly Aleph CCS) is having same voltage/current contribution as lower part of amp, practically amp acting as regular PP amp

if said gain is lesser than 50%, amp is leaning more to pure SE mode of operation, thus being more dependable of load value and behavior

now, having 604, efficient as bigbadaboom, you can try trick with load shunt - if you put 10-20W 16R resistor in parallel to spk, silly amp should think that 8R speaker is connected

some power to speaks, some heat to resistors, but who cares, with their efficiency

 

[generg]

Just finished my first Aleph J. What a wonderful amp, best of both worlds, clarity and softness at the same time.
M2 must go to the basement!

:--))

Some remarks, to get the 0.4V at the 0R47 I had to go down with the R27 68k to 15k, why ever.
Next days I will look for the H2 neg phase with Diana. In Spice I have to go to 2k for the R24/1k2 to see neg phase.

And by the way, I finally succeeded in getting neg phase H2 in Spice for A3 and A30. I was looking for this a long time. The solution was not to take the IRFP models in Spice, but the models for IRF240 for the A3 and the model for the IRF244 for the A30. Et voila!
Many people told me that the IRFP are a good replacement for the 240/244. I have no doubt it will work, but the H2 neg phase is a shy animal.

So for IRFP you have to play a longer time with the Aleph resistor to get neg Phase too.

 

[nicoch58]

woow @generg you are expert in papa amp ....soo good are ??

 

[generg]

Hi nicoch58, yes, I was surprised myself, class A at its best.

:--))

 

[ACnotDC]

Could you tell us how to detect or measure negative phase of H2 in LTspice?

 

[generg]

there is a add-on called residual decoder.... I found the site again:

https://www.diyaudio.com/community/threads/spice-simulation.101810/page-19#post-1333137

here my try with A3.

If you have more questions.... :--))