VSSA 50

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#41
Hi guys :wave:

Been busy this weekend finalizing NC1200+SMPS1200 amp, plus set the First One from being unstable to music reproduction.:wiz:
 

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#42
Lazy Cat said:
Hi guys :wave:

Been busy this weekend finalizing NC1200+SMPS1200 amp, plus set the First One from being unstable to music reproduction.:wiz:
Click to expand...

Ooooooh my eyes are getting wet... Drehkondensatoren!!! :yikes: (this is what variable caps are called in German. I remember those guys being built into my very first diy radio back in the 80s).

Keep going on, I really like your builds :cheers:
 
#43
Lazy Cat said:
Lazy Cat hasn't been very lazy lately. First One SMD populated PCB (50 x 80 mm) first time connected to SMPS600 and yes it will run on +/-64 V 😎
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😱 what is this ... ? with +/- 64v 🙄
LC what input pair you use & output only single pair, is that ok?
they must be very powerfulll 😀
No more film caps on feedback to ground, not needed anymore?

Regards
 
#45
Hi Andrej nice and Space filled, a comming costumer wont get disappointed i he looks under the Hood.
Joke (HeHe):
"VSSA in Lakner One chasis" = Amplifier with built in Power supply.
"First One in Lakner Two chasis" = Power supply unit with built in Amplifier.

JOHN BALI post 43 look at new image smd bypass caps under pcb for 22oouF FC elko.
BR Ricky
 
#46
Lazy Cat said:
:cheers:
Click to expand...
Hello LC

Will First One be 200W into 8 ohms? Is it DC coupled as you discussed earlier in the thread?

Will you be offering a GB or selling the First One as a commercial product?

I have a friend who wants a DC coupled amp of high power. He and I are discussing some loudspeaker measurements that require a DC amplifier.

In the SSA thread you mentioned someone may want global current feedback. Have you tried placing a resistor between the amplifier + out and the speaker and moving the amplifier feedback to the junction of the resistor and speaker? I will be trying this with a VSSA and SSA PCBs that I am in the process of building. This should turn the VSSA into a Howland Current Pump.

It wold be helpful if the First One has a jumper that can be removed so that the feedback point of the amplifier can be moved from where it is now to the junction of a series resistor between the amplifier + out and the speaker.
 
#47
I find, for my needs, that I need 200-250W/8 for the efficiency of the speakers and room volume/size, SPL. Minimum.

Do you have test equipment to do IM/THD et al tests on the finished product? PM me if you need some testing done.

Thx-RNMarsh
 
#49
Last monday i apply the diode/10R mod on my LC_VSSA modules. As they yet perfectly sound to my taste...For more flexibilty toward the speaker nature i'd like to have more power i remerber me the first VSSA iteration. One vssa limite toward Vdc rail amount is the Jfet CCS that have Vbr limited to 40V. As i didn't find , up to time, i another jfet with more suited Vbr i replace the Jfet ccs with the bjt-ccs that act in BG1/Versatil. If some experts can take a look at this point to validate? I swap too from ALF16 to 2 Renesas output pair as they are more purchaseable....See schematic and layout under. The board is design to be mount on heatsink with only 75mm height as FISCHER ELEKTRONIK SK56/75/SA.

Marc
 

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#50
Hi Marc,
I'm waiting the progress 🙂
the 22pF compensation caps maybe need higher value.
(I was use 22pF before but I also use 0.22 ohm source resistor)
My double output(J162+K1058 too) not stable yet & no CCS too...
That transistor CCS I should try to apply there, thanks
you give me some idea...

Regards
John
 
#51
Idefixes said:
Last monday i apply the diode/10R mod on my LC_VSSA modules. As they yet perfectly sound to my taste...For more flexibilty toward the speaker nature i'd like to have more power i remerber me the first VSSA iteration. One vssa limite toward Vdc rail amount is the Jfet CCS that have Vbr limited to 40V. As i didn't find , up to time, i another jfet with more suited Vbr i replace the Jfet ccs with the bjt-ccs that act in BG1/Versatil. If some experts can take a look at this point to validate? I swap too from ALF16 to 2 Renesas output pair as they are more purchaseable....See schematic and layout under. The board is design to be mount on heatsink with only 75mm height as FISCHER ELEKTRONIK SK56/75/SA.

Marc
Click to expand...
Very, very nice layout Marc!...:up:
 
#54
PMI said:
So this part is not readily available in Europe, either? That is disappointing. I found a few in stock in the US, but I was under the impression you can get it in Europe more easily, probably because the Alfets in general, are marked "UK stock".
Click to expand...

ALF16N16/20 and ALF16P16/20 are available from Newark french webshop (called Farnell), but they are quite expensive : about 14€/u

Marc
 
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