I used some Panasonics I had for C2 and C3. C1 not necessary. Just check that you do not have offset voltage there. The picture is from P.Daniel, not mine.
was asking because alweit is from Israel(2 weeks max shipping ) and spencer from Hong Kong(2 months shipping ) and I can't really wait that long now 😀
I see that alweit sold 274 items, I hope they are original
I see that alweit sold 274 items, I hope they are original
Schultzsch,
If the budget can stand it, try replacing C3 (220uF electro) with a 40 - 60 uF film cap - it enhances the whole performance of the amp - even the humble K73-16 russian caps are good here - will have to mount them offboard and isolate the metal cases but not a real problem.
C2 has less effect but surprisingly, the small C4 is quite noticeable (I used 470uNichicon FG for C2 and 47uF Rifa peg128 for C4 with a 1uF K73 bipass)- a definite 'mix-n-match' exercise.
Interesting how well the active current source works, particularly at both small detail and higher power.
If the budget can stand it, try replacing C3 (220uF electro) with a 40 - 60 uF film cap - it enhances the whole performance of the amp - even the humble K73-16 russian caps are good here - will have to mount them offboard and isolate the metal cases but not a real problem.
C2 has less effect but surprisingly, the small C4 is quite noticeable (I used 470uNichicon FG for C2 and 47uF Rifa peg128 for C4 with a 1uF K73 bipass)- a definite 'mix-n-match' exercise.
Interesting how well the active current source works, particularly at both small detail and higher power.
I had read somewhere around here that bigger C4 result in bigger turn on thump.Did you experienced that?
Dunno, I use DC protection cct and it has built in delay (mainly for the rail Cmx's to come up to voltage) - sorry, I can't be any use to you - perhaps best to just start small and see ....
I used the Rifa to suit the Fostex Fe167 speakers and in general, add a bit of "speed" to the amp - not the easiest caps to use - suggest start with a small Silmic - can easily change/upgrade (?) later.
I used the Rifa to suit the Fostex Fe167 speakers and in general, add a bit of "speed" to the amp - not the easiest caps to use - suggest start with a small Silmic - can easily change/upgrade (?) later.
Give you another one!
Look up the "a New Interconnect Design" thread here - (by Beau 2314, I think that's his numbers) - a diy version of those crazy priced battery biased interconnects.
You can get some of that fancy 0.5mm dia Mundorf Silver/gold wire from eBay (about $50 for 10 metres) for a rather analogue sound or that Ohno Pure Silver wire (with all the 9's -often marketed as Neotech but available w/out the insulation at reasonable prices) for a somewhat brighter, more mids sort of sound - detail without edge, unlike most silver ICs.
Oh yeah, try for better quality plugs/sockets/solder. Last pair I made used basic Lok plugs - about $9 each, if you look hard and patience - silver CMC sockets about the same.
All the best ...
Look up the "a New Interconnect Design" thread here - (by Beau 2314, I think that's his numbers) - a diy version of those crazy priced battery biased interconnects.
You can get some of that fancy 0.5mm dia Mundorf Silver/gold wire from eBay (about $50 for 10 metres) for a rather analogue sound or that Ohno Pure Silver wire (with all the 9's -often marketed as Neotech but available w/out the insulation at reasonable prices) for a somewhat brighter, more mids sort of sound - detail without edge, unlike most silver ICs.
Oh yeah, try for better quality plugs/sockets/solder. Last pair I made used basic Lok plugs - about $9 each, if you look hard and patience - silver CMC sockets about the same.
All the best ...
was asking because alweit is from Israel(2 weeks max shipping ) and spencer from Hong Kong(2 months shipping ) and I can't really wait that long now 😀
I see that alweit sold 274 items, I hope they are original
I told you - buy locally J271 jfets ( observe - not 2S in front ! ) and use them
even if they have higher Idss , they're biased here with CCS , so no problem
xconductance will be adequate
and later - if you want , replace them with 2SJ74BL , but I doubt you'll hear significant difference
I think i will order 20-30 J271 from farnell. I will have them by thursday.
If I'll want to use in the future more output devices(6) how will these J271 work in comparison with J74BL.Will the higher idss of J271 help me if set properly from the ccs?
If I'll want to use in the future more output devices(6) how will these J271 work in comparison with J74BL.Will the higher idss of J271 help me if set properly from the ccs?
in this case I have to get them all 4 matched right?
pretty long quest to get something done as you want specially with these fake parts, I am pretty dissapointed for the moment but hope to recover untill thursaday 😀
pretty long quest to get something done as you want specially with these fake parts, I am pretty dissapointed for the moment but hope to recover untill thursaday 😀
finally...started one channel
dc offset 50mV and going down, bias 1.75A
rail voltage 23.6v
UR8 - 8.3V
UR7 - 4.9V
dc offset 50mV and going down, bias 1.75A
rail voltage 23.6v
UR8 - 8.3V
UR7 - 4.9V
The bias drops at about 1.6A per fet after an hour or so, heatsink temp rises at 50C and junction temp at 82C
Rail voltage is +/- 23.6V
What would be the power output in 3.5 ohms?
Very nice sounding amp for the begining but a better impresion will be after burnin.How much does this takes?
Thank you all for your help and to specially you Papa for the schematic and hard work you did so we can enjoy the sound
Will be back with conclusions
Rail voltage is +/- 23.6V
What would be the power output in 3.5 ohms?
Very nice sounding amp for the begining but a better impresion will be after burnin.How much does this takes?
Thank you all for your help and to specially you Papa for the schematic and hard work you did so we can enjoy the sound
Will be back with conclusions
you're using 2 pairs of output mosfets , so 3A2 Iq per channel ?
btw. which input Jfets you are using , finally ?
btw. which input Jfets you are using , finally ?
what's exact voltage across any of 4 source resistors ( 0R39) ?
btw - burn in is mostly depending of C3 type ; what type you're using ?
btw - burn in is mostly depending of C3 type ; what type you're using ?
I have 0.33R source resistors and voltage across them is in the range 0.520-0.550V
For C3 i use Panasonic FC
For C3 i use Panasonic FC
bypass that FC with some nice MKC (polycarbonat) in range of 10-100nF
you have slightly under 60W/3R6 , considering hefty Iq , with that PSU voltage
what case you're using - that's plenty of dissipation ......... ?
you have slightly under 60W/3R6 , considering hefty Iq , with that PSU voltage
what case you're using - that's plenty of dissipation ......... ?