L'Amp: A simple SIT Amp

Member
Joined 2009
Paid Member
VICTORY.......humfree, Yippee.....:):):):):):):):):)

that means that it is no good idea to use the FW PSU with the symmetric voltages....

I made it point to point my ...........most favorite way!

I enclosed a bit a reluctant a picture, please do not forget this case has seen during the last two years

F5 mono PSU, dual PSU, F4, BA-1, BA-2, BA-1 with Semisouth, F1J, F2J,F3, Aleph3, Aleph30, Aleph5,BJ2, M2clone (crippled F4 with different xformers), xformers with 2x18V 300W, 2x30V 400W,2x18V 500W.........SIT

so you understand it is a bit dirty and worn, but it served me well.....:) and now you understand better my signature....:cool:

I THANK YOU ALL!
:D:D:D:D:D
 

Attachments

  • 106_0072.jpg
    106_0072.jpg
    94.4 KB · Views: 772
Last edited:
Hope everyone have a great time, i certainly do!

The prototype amp is now done and works very fine indeed.. I'm running it at 32V and about 1.6-1.7a (each channel), i think the heat sinks are good enough for that as they "only" get to about ~50C..And the resistors? a whopping ~150C at current power :cool:

The sound is awesome, the sweetness, the speed, the NUANCES, the big SPACE between the notes are just nothing but amazing.. It's just that, the timeless and sweet feeling and almost infinite space between the notes Is sure has that "sitting up all night" quality to it too. I can't wait to get some more proper cooling and push the power a little..

A tip might be to use a BJT based cap-multiplier in the PSU, just a thought.. I use it total hum-free with a total of 15,000uF for both channels as i don't like amps running something like 80,000uF+ (sounds slow with dull nuances if you ask me)
 

Attachments

  • amp_complete.jpg
    amp_complete.jpg
    209.3 KB · Views: 753
Member
Joined 2009
Paid Member
Hi Chris, would be happy if my prototypes would look like this....:)

I will start with the second channel today and try again in direct comparison the Mufollower and all the CCSs Salas suggested....

the last try with the Mu was a bit unfavorable :mad: , I choked the upper SemiS by only implementing the bias network but no 47k :eek: to prevent the signal going the sides away....

So repetition is matter of honor...:knight:
 
Seems interr.....

Hope everyone have a great time, i certainly do!

The prototype amp is now done and works very fine indeed.. I'm running it at 32V and about 1.6-1.7a (each channel), i think the heat sinks are good enough for that as they "only" get to about ~50C..And the resistors? a whopping ~150C at current power :cool:

The sound is awesome, the sweetness, the speed, the NUANCES, the big SPACE between the notes are just nothing but amazing.. It's just that, the timeless and sweet feeling and almost infinite space between the notes Is sure has that "sitting up all night" quality to it too. I can't wait to get some more proper cooling and push the power a little..

A tip might be to use a BJT based cap-multiplier in the PSU, just a thought.. I use it total hum-free with a total of 15,000uF for both channels as i don't like amps running something like 80,000uF+ (sounds slow with dull nuances if you ask me)

Hi Chris!

Your solution seems like a "easier" solution - with not so high voltage and smaller caps! The big heat sinks that is req is ok - but the somewhat smaller size on the the PSU is more to my liking.

I have not yet decided how to build my LÀmp - so my SK82 is still waiting for a "sound" solution. Whatever that means?

So Chris - will you provide some info, schematic how your amp is - when it is more or less finished? And what speakers you are driving your version with?

Will be VERY grateful for an answer( and my B1 - that is soon to be finished) will be a happy partner - somewhere in time!

Greatings to all.

Olav
 
Hi Chris!

Your solution seems like a "easier" solution - with not so high voltage and smaller caps! The big heat sinks that is req is ok - but the somewhat smaller size on the the PSU is more to my liking.

I have not yet decided how to build my LÀmp - so my SK82 is still waiting for a "sound" solution. Whatever that means?

So Chris - will you provide some info, schematic how your amp is - when it is more or less finished? And what speakers you are driving your version with?

Will be VERY grateful for an answer( and my B1 - that is soon to be finished) will be a happy partner - somewhere in time!

Greatings to all.

Olav

Hello,

My PSU is super simple using just a single 2n3055 BJT. i made a simple schematic too

at the moment i'm only using one single PSU as in the schematic (except i use discrete diodes instead of the bridge)

I might make a schematic for the amp too if anyone really want that :p

I'm using a couple von schweikert VR2 at the moment, have no trouble with insufficient volume levels, and that is at 32V supply

When i get more serious with my heat sink i probably will make a 45-50V PSU with another gyrator/cap-multiplier, using one or two "transformers+rectifiers+first-cap"

And Thank Michael for making the Great article about this project, super-fun read indeed! :cool:
 

Attachments

  • psu.jpg
    psu.jpg
    41.7 KB · Views: 804
Pass DIY Apprentice
Joined 2001
Paid Member
...I'm running it at 32V and about 1.6-1.7a...

That sounds just about right. With a 32V supply, 12 Ohm drain load, 8 Ohm speaker, Vds = 12V, Id=1.62A I see .4% THD @ 1W. I'd call it a 2.5-3 Watt amp. At 2.5W, we're at around 1.35% THD. I'd say you've got it dialed-in pretty well, now you can fine tune it to taste.
 
That sounds just about right. With a 32V supply, 12 Ohm drain load, 8 Ohm speaker, Vds = 12V, Id=1.62A I see .4% THD @ 1W. I'd call it a 2.5-3 Watt amp. At 2.5W, we're at around 1.35% THD. I'd say you've got it dialed-in pretty well, now you can fine tune it to taste.

I wish i had a THD analyzer (or even better, a spectrum analyzer) too, would be great fun. I might work on some fine tuning later on, but not too sure that it would do much good without measuring the THD/spectrum.

I get quite nice level of volume with 1-1.5V RMS input and using it directly with the outputs from my DAC, no volume control or preamp for uttermost purity :p

Would you or anyone else using (BIG)C+R+(BIG)C PSU consider building the one i use at the moment and compare the different sound? Would be fun to see if we get at the same results

PS: I might add that i use 1000uF located in the amp for each channel and running a power cord for each channel to the PSU.

I was thinking how i was going to construct the more final version, dual mono block or a separate PSU+amp.. I am leaning towards the later with or without true dual PSU..
 
Last edited:
:cheers::cheers: YEEPEEEEEEEE YEAHHHHHHHH , wonderfull , merveilleux ,c'est Formidable!!!!

my SIT is on fire, 17V , 2,77 amp a BIG sound a little hum with my 102db horn speaker. but definitly too much gain with my threshold SL10 , i make a mistake not too buy a BC1 ..:(

pics to come...

for the hum do you have a resistor between hot and groun:rolleyes:d of the input RCA ?