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
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
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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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 I’m expecting a subjective answer that may represent your taste, but it’s 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
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
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
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
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
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
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
I wish i had the parts, i'd drop this into one of my A2 monoblocks tonight!
a nice way to experiment, without destroying the original front end...
A JFET, A JFET, my Aleph 2s for a JFET!!! (matched pairs please) 😎
Now i'm wondering how it would effect the sound... maybe help the top end of the A2?
maybe give it a bit more air? -i'm thinking subtle effects here...
a nice way to experiment, without destroying the original front end...
A JFET, A JFET, my Aleph 2s for a JFET!!! (matched pairs please) 😎
Now i'm wondering how it would effect the sound... maybe help the top end of the A2?
maybe give it a bit more air? -i'm thinking subtle effects here...
Hi Bob,
By my calculations the cascode transistors have about 25 volts or so across them and 5 ma of current flowing. That gives 125mw of dissipation. Seems safe to me without a heat sink. I used the ON SEMI data sheet off Digikey. Seems well within the SOA.
Graeme
By my calculations the cascode transistors have about 25 volts or so across them and 5 ma of current flowing. That gives 125mw of dissipation. Seems safe to me without a heat sink. I used the ON SEMI data sheet off Digikey. Seems well within the SOA.
Graeme
yup
small TO92 clip on heatsinks is wise to put there
or ....... use something as BD140 for cascodes , then no need for heatsinks
gl - I think 221R@5V is programming for CCS
small TO92 clip on heatsinks is wise to put there
or ....... use something as BD140 for cascodes , then no need for heatsinks
gl - I think 221R@5V is programming for CCS
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yup
they're fancy
BD139/140 , even if old almost as 2N3055 , are still very useful ........
though - those, you mention , are certainly easier to get in US then BD variety
they're fancy
BD139/140 , even if old almost as 2N3055 , are still very useful ........
though - those, you mention , are certainly easier to get in US then BD variety
I stand corrected. The cascodes are running 10ma apiece here. So heatsinks or bigger transistors are needed.
On the AX100J I doubled up on the cascode transistors. I was remembering that circuit. Apologies.
Graeme
On the AX100J I doubled up on the cascode transistors. I was remembering that circuit. Apologies.
Graeme
no need for apologies
what I forgot at end ( when needed ) and BobEllis pointed well , is that we are dealing here with 45V rails ...... realm where one need to be careful with tiny parts
what I forgot at end ( when needed ) and BobEllis pointed well , is that we are dealing here with 45V rails ...... realm where one need to be careful with tiny parts
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