L'Amp: A simple SIT Amp

[peppennino]

Yes, sorry, typo. Thanks

 

[Soundhappy]

@ Peppennio

I am curious how its sound with light bulb but other Diyers write with power resistors sound is very good as well. If you don't want use 3 or 4 cheap wire wound resistors in series
https://www.ebay.com/sch/i.html?_from=R40&_nkw=100+watts+wirewound+resistor&_sacat=0&_sop=15
the alternative choice can be something like that
👀 NEW EBG ULTRA HIGH POWER RESISTOR UXP/600 - 13R5K - 336A3594SSP2 | eBay

 

[peppennino]

What a beast!
I only need a few watt for my BLHs in small room, so the V1 version should be ok

 

[Soundhappy]

Yes industrial resistor to put on the heatsink with layer of thermal paste
Output impedance = total bulb resistance 11~13R
I see 1R less used 10 pcs. of 10R rated at 300W at good price
QTY:10, EBG (VISHAY) UXP/300 10RK 10 OHM/10OHM 300W FOIL NON-IND.POWER RESISTOR | eBay
Could be interesting resistor model to try with big Tokin as well

 

[peppennino]

Meeeeerciiii Christophe!

 

[plasnu]

Very interesting parts. Thank you, Soundhappy.

 

[Soundhappy]

@ Peppennino and Plasnu

Enjoy 9 fascinating DIY pages to read with photos about different L'Amp versions
SIT amp project - DIY - HiFi WigWam + the sweet cherry on the TOP SIT part Deux - DIY - HiFi WigWam

 

[Soundhappy]

Actually nobody build L'Amp mono blocks
with one light bulb in parallel with the power resistor(s)
EBG Resistors, manufacturer of high voltage, power thick film resistors

 

[peppennino]

Are you referring to the version with or without negative bias circuit? Mine (if I can find the Vfets) will drive two FE127E in reflex or two 103En in blh, so a 8ohm extra easy load

 

[Soundhappy]

Use LM7912 (-) bias supply for 2SK82 | PSU (+) on the Vfet drain
LM7812 is (+) bias supply for 2SJ28 | PSU (-) on the Vfet drain

Bulb or bulbs in paralell , high power resisitor(s) or mixture of bulb(s) paralelled with high power resistor(s), CCS with Mosfet or L inductor is Your choice decision.

After my new Papa Vfet SE build experience SMPS psu is stabilized and quiet, can be interesting to try in L'Amp how is good
but we need think about and experiment how avoid smps hiccup protection if large capacitors are used
on add external CLC filtering boards Greetings

 

[Soundhappy]

..so a 8ohm extra easy load

Look at Mr. MR post # 3 L'Amp: A simple SIT Amp

Yes original L'Amp circuit is optimised for 8 Ohms speakers load

 

[alexopth1512]

Use LM7912 (-) bias supply for 2SK82 | PSU (+) on the Vfet drain
LM7812 is (+) bias supply for 2SJ28 | PSU (-) on the Vfet drain

Bulb or bulbs in paralell , high power resisitor(s) or mixture of bulb(s) paralelled with high power resistor(s), CCS with Mosfet or L inductor is Your choice decision.

After my new Papa Vfet SE build experience SMPS psu is stabilized and quiet, can be interesting to try in L'Amp how is good
but we need think about and experiment how avoid smps hiccup protection if large capacitors are used
on add external CLC filtering boards Greetings

i have used smps with large CLC, had no issue

 

[Soundhappy]

@ Alexopth1512 and Diyers

Great What about regulated supply for L'Amp https://www.firstwatt.com/pdf/art_zv3.pdf

 

[slimecity]

From my own experience, I never used the bulbs. I started with the large resistors, then went to the Hammond chokes- doing this "cleaned" the output SQ considerably. It just sounded "tighter" and "tidier."

 

[Soundhappy]

@ Slimecity

What was your power resistors choice ? mox, wirewound, film etc. ?

I know only L'Amp version with Hammond chokes so want try something different

 

[peppennino]

Also differences between channel (2SK82 or 2SJ28) used would be interesting...

 

[alexopth1512]

@ Alexopth1512 and Diyers

Great What about regulated supply for L'Amp https://www.firstwatt.com/pdf/art_zv3.pdf

Yes regulated also works just fine. Use figure 2, putting a big CLC in front. I use more than 40mF for each capacitor and 3mH air for L. For reg FET I ended up in IRFP260 and lately in IRFP4468. You must carefully choose Z1,Z2 and C1, it is very important.
Result is fantastic, plus you don't hear the slightest hum, even if you put your ear inside the woofer.

For resistors, I have used:
- Wirewound 100W resistors on sinks in parallel
- 110V halogen 500W lamps
- Hammond 193V
- Hammond 195T5
- Custom choke 120mH/8A

Best sound is with chokes. 193V has best bass and sweetest highs but gets really hot.
195T5 less bass than 193V but more highs in quantity, not as sweet as 193V.
Custom one something in the middle.

 

[Soundhappy]

Thank Alexopth1512

for your regulated psu informations about components choice.
You have try with CCS ? Sound fantastic in Pass Vfet SE

 

[alexopth1512]

No haven't tried CCS, because I don't want more heat, I am at 60V/8A and I am trying to find ways to avoid heat

I only use SMPS to test the system, because it has variable output and I don't have VARIAC.

I use toroidal huge transformers on normal operation and to me sounds much better from SMPS.

I have the VFETs but haven't tried them yet on L'Amp, because after some months i have just finished with IXYS building, I am very close to test with SICs, I always test SICs before the VFETs.

 

[Soundhappy]

What L'Amp better sound with SMPS or regulated power supply ?