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Old 7th March 2014, 12:46 AM   #21
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it looks good
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Old 7th March 2014, 12:13 PM   #22
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it looks good
Thank you for all yours comments, without your help this would be impossible to do for me.

As soon as possible I will collect the parts and look for a place to make PCB.


Have a nice day.
Alejandro
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Old 7th March 2014, 12:55 PM   #23
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maybe you can dream about this one , later

regarding pcb - all you need is some pcb raw material , good alcohol based marker , and ..... google for hydrogen peroxide pcb etching

or just make it on universal pcb - those ones with matrix of little dots
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File Type: pdf Babelfish Aleph 2.pdf (43.7 KB, 95 views)
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Last edited by Zen Mod; 7th March 2014 at 12:58 PM.
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Old 7th March 2014, 04:55 PM   #24
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Originally Posted by Zen Mod View Post
maybe you can dream about this one , later

regarding pcb - all you need is some pcb raw material , good alcohol based marker , and ..... google for hydrogen peroxide pcb etching

or just make it on universal pcb - those ones with matrix of little dots

I'm currently looking for different sources for the PCB, I'm waiting for a quote from a local & overseas suppliers.

Wow!!, Babelfish Aleph 2 version utilize just two 2sj74. Why BC556A?, there are a lot of similar models BC556BTA, BC556ATA, BC556BTF, BC556BTFR, BC556ABU, BC556BG, with the exception of last one all appears to have similar parameters.

What is your impression of Babelfish Aleph 2 sound?, I know Iím expecting a subjective answer that may represent your taste, but itís important to me. I like mids and a good bass but not excessive to move my entire house. I use to listen Jazz from digital and analog sources.

I was making plans to in a near future build the AlephJ-X using the Graeme schema, but the Babelfish Aleph 2 could be a good alternative too, I'm already have the transformers and power supplies for that voltage.

Another question, in the standard Aleph 2 the MPSA18 can be replaced by a ZTX450 as in Aleph 4, 30 and 60.


Regards,
Alejandro
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Old 7th March 2014, 05:34 PM   #25
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I would stay with your original Aleph 2J plan. Zen did say that his recommendation was for later.

In case you didn't know, member Wayne who made the recommendation earlier in your thread is one of the partners in Pass Labs. So consider your original project to be blessed.

Any of the BC556 transistors will work as a cascode here.

Stay with two 2SJ74BL transistors on each side. At 5ma each they are working hard already and the total current at 10ma in each leg of the diff pair is the same as the original Aleph 2. If you start changing things too much then you may start creating design issues that are too difficult to resolve. Take things slowly and one small step at a time.

Graeme
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Old 7th March 2014, 05:43 PM   #26
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BC556A or MPSA or ZTX - that's all the same , considering their role in circuit

Babelfish Aleph 2 - I didn't tried it as drawn , but I don't have reason to doubt it - I drew that for someone asking how to put JFets in Aleph 2 , few months ago

sound - you heard one Aleph , you heard them all ....... scaling up just for power you need for task

I'm expecting that implementing cascoded bjt buffer between JFet input LTP is clearing sound for step more , referring to change from mosfet LTP to JFet one ....... but - will that please your ears , that's completely on you

I know , when I tried buffer there few years ago , in my Babelfish J prototype , I found efforts well paid of

and - once more - all these small bjts - you can consider them as universal types .... sort of

edit - as gl pointed - stay with already made plan , for start ; so - 2+2 JFet LTP , instead of IRF LTP
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Old 7th March 2014, 06:01 PM   #27
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Thank you ZM. That clarifies your recommendation nicely.

Can someone explain why R71 is present in this schematic. It's present on the Aleph-J schematic from the DIYA store too. In Alejandro's schematic the only purpose I can see is to reduce the power dissipated by the CCS transistor. But the existing IRF9610 in the Aleph 2 is already handling that just fine.

Graeme
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Old 7th March 2014, 06:31 PM   #28
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if you see resistor in series with CCS , it's always there only for dissipation reasons
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Old 7th March 2014, 06:49 PM   #29
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Then if this was my project I would delete R71.
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Old 7th March 2014, 06:59 PM   #30
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feel free to do that
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