My Aleph3/5-BA-2-Semisouth-J2 Clone Monster

generg

Member
Paid Member
2009-07-17 1:22 pm
Near Frankfurt
Hi everybody,:D:D:D

it would be very kind if you would post comments if my clonemonster is O:K or K:O :)

I build up an Aleph 3 because the Aleph current source is so adjusted that he delivers 60W into 4 Ohm speakers and even 60W in 2 Ohms.
This is very favorable for me because my Thiel speakers have 3,7 Ohm and only 87db.

I changed the unbalanced input to a balanced by using the values of aleph 5.
10k resistors in the input and to ground and 100k feedback resistor.

I changed now the ZVP3310 and IRF9610 CCS against two pairs of J74 for the input (matched) and a current source with two 2SK170 giving 16 mA. (J2 is greeting), made roughly in the way the frontstage of BA-2 works.

I changed the lower (negative side) IRF against Semisouth R100.

I adjusted the offset current and the Vgs with a pot like Nelson advised for Aleph J thread to 1,2V.

My main question is the Aleph CCS still working after all modifications?, Should I readjust it? In which direction to keep the high power with 4 Ohm.

Are at high power levels both, the SemiR100 and the IRF working together, so I get a sound mix?

Ha, ha, you see I am a beginner still.....:D:D
 
......

My main question is the Aleph CCS still working after all modifications?, Should I readjust it? In which direction to keep the high power with 4 Ohm.

Are at high power levels both, the SemiR100 and the IRF working together, so I get a sound mix?

Ha, ha, you see I am a beginner still.....:D:D

looking at ser. man. of Aleph 3 :

important points for 4/2 ohms operation are values of R122 in conjunction with R109 & R110 , adjusting value of output stage current begrenzung ;

higher value of R109 means higher max current stage will deliver

also - value of R14 adjusts AC gain of Aleph CCS ; easiest way to achieve best AC gain for blending Jfet and mosfet part of output will be observing clipping ( symmetry) with dummy load on output , not without .
 

generg

Member
Paid Member
2009-07-17 1:22 pm
Near Frankfurt
thank you Zen Mod!:D:D

In the Zen papers Nelson describes the advantages of the aleph current source mostly in relation to distortion reduction and how to set the value or the resistor for the dynamic feedback, but I did not found or understand really why it ameliorates the power at 4 Ohm in the case of A3. It seems he can decide the aleph to enforce power at 4 Ohm or 16 Ohm as he likes. Which parts are doing this and how to change?:confused::confused:
 
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OK

output current is dependent of two things -
1.set value of current clamp in neg leg ( that's small bjt in lower side , which role is to strangle gate of adjacent output when current through source resistor is approaching set value
2. pretty much dependable of >1< - AC gain of Aleph CCS ...... but there you must think of both voltage and current gain

for start - you can alter already mentioned values - R109 to be precise , but I can't tell you more without seeing actual schematic of your output stage ; meaning on value of Jfet source resistor(s) , type of mosfets in Aleph CCS etc
 

generg

Member
Paid Member
2009-07-17 1:22 pm
Near Frankfurt
with a little shame the circuit :eek: .... only hand corrected, I could not manage photoshop sufficiently......
 

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generg

Member
Paid Member
2009-07-17 1:22 pm
Near Frankfurt
l::):) thanks Bill,

I omitted the Zener already and 500 Ohm is the value Aleph 5 has installed. I will try different values.
Highs and medium area are good, bass is less than with pure A3, maybe Mos-Fet bloom is away, I´ll build in a supplementary special produced for generg Bloom-Fet ::::::::::::D:D:D:D:D:cool:
 
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