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LOL…didn’t you say Greediest Boy who dies with most toys has big grin on his face at funeral?
That’s why I ordered them!
That’s why I ordered them!
I believe those deserve their own thread, be it here or speaker sub forum. But we need details on how this plays out.
OK…I know this is under “when you cross that bridge” and all that.
Numero Due boards are completely populated…connections ready etc.
I am building this second J2 with all irfp150 initially as I did Numero Uno for safety of unobtainium Semisouths to be added afterwards.
All that’s left is to put boards in case, plug in all power and signal connections and “fire in the hole!”
I have installed sockets at R118(218), R122(R222)and R123(R223) as with previous set of boards.
Their values are set as:
R118=820R
R122=270R
R123=220R
Looked back over start up notes and different iterations ZM posted schematics for circuit.
Not going with altered MOX values right now regardless…original values are mounted.
I see a note about DC offset and making it “friendlier” for Semisouth by adding up to 100K across R139/239?
This is tiny SMD on bottom of board that requires pulling boards again.
Is increasing resistance at R139/239 a given to get DC offset to behave with Semisouth?
Can the 100K be mounted now and still allow DC offset adjustment with irfp150 in circuit?
Measurement across R139/239 gives only .5 Ohm or so when I checked.
Someone posted that adjustment to R123 was necessary to get the circuit to work with Semisouth.
I’m assuming that was to achieve a desired bias setting as there is also a note mentioning an increase of values at R118 and R123 if additional adjustment is needed.
Numero Due boards are completely populated…connections ready etc.
I am building this second J2 with all irfp150 initially as I did Numero Uno for safety of unobtainium Semisouths to be added afterwards.
All that’s left is to put boards in case, plug in all power and signal connections and “fire in the hole!”
I have installed sockets at R118(218), R122(R222)and R123(R223) as with previous set of boards.
Their values are set as:
R118=820R
R122=270R
R123=220R
Looked back over start up notes and different iterations ZM posted schematics for circuit.
Not going with altered MOX values right now regardless…original values are mounted.
I see a note about DC offset and making it “friendlier” for Semisouth by adding up to 100K across R139/239?
This is tiny SMD on bottom of board that requires pulling boards again.
Is increasing resistance at R139/239 a given to get DC offset to behave with Semisouth?
Can the 100K be mounted now and still allow DC offset adjustment with irfp150 in circuit?
Measurement across R139/239 gives only .5 Ohm or so when I checked.
Someone posted that adjustment to R123 was necessary to get the circuit to work with Semisouth.
I’m assuming that was to achieve a desired bias setting as there is also a note mentioning an increase of values at R118 and R123 if additional adjustment is needed.
Thanks codyt…looks like you were going full Semisouth.
Not sure I’ll have the same set of issues…my intention was to go Semisouth down after building them full irfp.
I could go full Semisouth, but I’m saving part of my hoard to pursue my J fetish further in the future.
Not sure I’ll have the same set of issues…my intention was to go Semisouth down after building them full irfp.
I could go full Semisouth, but I’m saving part of my hoard to pursue my J fetish further in the future.
heavy lightning and thunders, so lost electricity...
will reply tomorrow
can do nuttin' via phone
will reply tomorrow
can do nuttin' via phone
Said the hell with it and slapped everything together this afternoon.
First channel of Numero Due is fired up and cooking…no drama as of yet.
Twiddled Iq pot to bring it in line with 670mV that I set Numero Uno at which resulted in a temp equilibrium of 50-55 C on these heatsinks. Took maybe 4-5 turns on the pot as it started out around 750mV when I banged it on.
Had about 150 mV of DC offset…no problem twiddling that out either. Its dancing back and forth 10mV or so around 0.00.
Will wait for it to cook up to temp and twiddle some more…then onto second channel.
I’ll just have to suck it up and pull the boards if I need more resistance across R138/239 once I mount Semisouth down to get the offset to play nice.
First channel of Numero Due is fired up and cooking…no drama as of yet.
Twiddled Iq pot to bring it in line with 670mV that I set Numero Uno at which resulted in a temp equilibrium of 50-55 C on these heatsinks. Took maybe 4-5 turns on the pot as it started out around 750mV when I banged it on.
Had about 150 mV of DC offset…no problem twiddling that out either. Its dancing back and forth 10mV or so around 0.00.
Will wait for it to cook up to temp and twiddle some more…then onto second channel.
I’ll just have to suck it up and pull the boards if I need more resistance across R138/239 once I mount Semisouth down to get the offset to play nice.
Attachments
that liquid under the speakers is ....... they're weeping ....... for proper cabs
you didn't heard them at all, in that
ever tried driving a bicycle with one crank broken?
you didn't heard them at all, in that
ever tried driving a bicycle with one crank broken?
I know I know…other antics to follow…there will be MLTL goodness at some point…I have the 12” Tannoys I’m not so shy about and now the Sonidos too!…have to get back into cabinetry mode
One thing I noticed again is that I get a lot of snowy hiss from the speakers noticable near them with no music playing when these amps are combined with my tube Audible Delusions 2D pre…no hiss at all when the push pull Quicksilver tube amps are in place driving Tannoys
no hiss issues noticed with ACAs, F2J monoblocks or VFET amps
Is this due to gain or impedance mismatch you think? Just noisy tubes in preamp?
One thing I noticed again is that I get a lot of snowy hiss from the speakers noticable near them with no music playing when these amps are combined with my tube Audible Delusions 2D pre…no hiss at all when the push pull Quicksilver tube amps are in place driving Tannoys
no hiss issues noticed with ACAs, F2J monoblocks or VFET amps
Is this due to gain or impedance mismatch you think? Just noisy tubes in preamp?
if there is no noise with any other line stage or even passive or even direct source (having inherent volume), then it's preamp cause
made some listening tests of new FC speakers, even bare naked?
that's my fave way of testing new ones - bare, listening solely mid and highs
made some listening tests of new FC speakers, even bare naked?
that's my fave way of testing new ones - bare, listening solely mid and highs
aha
Dellusions is really delusional
30db of gain, combined with BJ2, recipe for hiss
that thingie isn't worthy even of F4, adequate with gain figure but generic construction, to put it mildly
Dellusions is really delusional
30db of gain, combined with BJ2, recipe for hiss
that thingie isn't worthy even of F4, adequate with gain figure but generic construction, to put it mildly
That’s what I guessed was the issue…I’ve had issues matching gain to the phono section as well. Once I moved to MC it became useless.
My DCB1 with iron on output is dead silent and direct signal from digital iPad etc is also silent
The AI has had its place and time in my life and really doesn’t sound bad in the right scenario…but drives the hell out of the tubes and creates a lot of heat that results in it eating tubes much faster than it should
Its time to build my big boy Iron Pumpkin/Turtle
My DCB1 with iron on output is dead silent and direct signal from digital iPad etc is also silent
The AI has had its place and time in my life and really doesn’t sound bad in the right scenario…but drives the hell out of the tubes and creates a lot of heat that results in it eating tubes much faster than it should
Its time to build my big boy Iron Pumpkin/Turtle
So I was mistaken…there’s drama with the second amp
The noise through the Tannoys from the AI pre was the majority, but further testing with AI disconnected and more sensitive fullranges connected to the amp without a source exposed buzzing similar to when I fired up my first BJ2.
I went back through comparing the build of both amps, only a few things stuck out. A few wires that could be a little shorter. Twisting both pairs of twisted transformer secondaries together. Now, as far as I can tell they’re identical builds.
When I was poking around inside shifting the DC power supply wires running to the amp boards seemed to affect the noise level the most.
I tried pushing the the DC wires away from the transformers and power supply boards under the amp boards and the buzzing got quieter. They were part of what I shortened when I noticed the first amp had slightly shorter DC wiring.
So first one is dead silent…second one has slight faint buzzing.
Not sure if its just bad luck or what…I’d rather both were dead silent.
Any ideas?
First pic with brighter lighting is of buzzing amp on work bench.
The noise through the Tannoys from the AI pre was the majority, but further testing with AI disconnected and more sensitive fullranges connected to the amp without a source exposed buzzing similar to when I fired up my first BJ2.
I went back through comparing the build of both amps, only a few things stuck out. A few wires that could be a little shorter. Twisting both pairs of twisted transformer secondaries together. Now, as far as I can tell they’re identical builds.
When I was poking around inside shifting the DC power supply wires running to the amp boards seemed to affect the noise level the most.
I tried pushing the the DC wires away from the transformers and power supply boards under the amp boards and the buzzing got quieter. They were part of what I shortened when I noticed the first amp had slightly shorter DC wiring.
So first one is dead silent…second one has slight faint buzzing.
Not sure if its just bad luck or what…I’d rather both were dead silent.
Any ideas?
First pic with brighter lighting is of buzzing amp on work bench.
Attachments
both channels buzzing?
well, this is the thing I'm rarely doing, but this amp is of those benefiting with coax cable to input
so, that's first thing; simple test - if you close input twisted pair with your fingers, and there is less buzz, go for coax
we'll see after
well, this is the thing I'm rarely doing, but this amp is of those benefiting with coax cable to input
so, that's first thing; simple test - if you close input twisted pair with your fingers, and there is less buzz, go for coax
we'll see after