Hi Still4given,
the onboard caps are just supersize decoupling caps, nomally specified at 47uF to 220uF.
Your PSU caps should send real DC to the board. I do not recommend you connect your bridge to the board, keep the AC away from the board.
Your two stage smoothing has two central caps that supply two channels. These first stage caps will be working hard due to seeing all the AC and doing twice the current. These MUST have high (adequate) ripple capacity. You do not need massive cap here 4700uF would do. The second stage smoothing after the inline resistors need to be large. This is the main dynamic supply to meet variable loads. I recommend 20mF to 30mF on each rail to each channel.
Since the decoupling is large I think you could reduce the second stage slightly i.e. to about 15mF since this suits your existing stock.
the onboard caps are just supersize decoupling caps, nomally specified at 47uF to 220uF.
Your PSU caps should send real DC to the board. I do not recommend you connect your bridge to the board, keep the AC away from the board.
Your two stage smoothing has two central caps that supply two channels. These first stage caps will be working hard due to seeing all the AC and doing twice the current. These MUST have high (adequate) ripple capacity. You do not need massive cap here 4700uF would do. The second stage smoothing after the inline resistors need to be large. This is the main dynamic supply to meet variable loads. I recommend 20mF to 30mF on each rail to each channel.
Since the decoupling is large I think you could reduce the second stage slightly i.e. to about 15mF since this suits your existing stock.
Regarding caps,
I still have a nice stock of 10.000µF 63V caps, so if anybody needs some for this project let me know.....
They will fit the board and support 50V rails (36V 0 36V AC transformers)
\Jens
I still have a nice stock of 10.000µF 63V caps, so if anybody needs some for this project let me know.....
They will fit the board and support 50V rails (36V 0 36V AC transformers)
\Jens
ble0t said:
If you plan to use R68/R69, using the original values is a mistake.
I28+I26-I68= I41+I42+I43. (I28 is current through R28)
The MPSA's T10 and T12 open up when there is 0.6 volts across R28 or R30, but that depends on the currents through R26 and R68, respectively R34 and R69.
You might post the kind of output devices and rail voltage you intend to use.
imo, R28/R26/R68/R41+R42+R43 are simple voltage dividers, but without the max current value and chosen voltage there isnt much sense in talking about resistor values.
Ahhh....thank you for that post jacco...that's what I get for not looking at the schematic closely enough 
I'm planning on using the MJL4281 / MJL4302 with 56V rails. Hopefully, I'll get a chance to take a look at the resistor values at lunch today.
Much appreciated!
I'm planning on using the MJL4281 / MJL4302 with 56V rails. Hopefully, I'll get a chance to take a look at the resistor values at lunch today.
Much appreciated!
I just want to say I got my boards several days ago. They look very nice. I’m very surprised about how thick they are. I have to figure out how to cut these or maybe I’ll just leave them intact.
Leve
Leve
LBHajdu said:
You're going to have a tough time getting the thermal diodes to work properly if you don't get them mounted on the heatsink. I guess you could always forget about the diode board and drill them into the heatsink like the original design.
Blessings, Terry
parts
I'm thinking of using an Avel xformer at 800 VA to cover both channels. No dual mono for me on this design. Think i'll use MJL21195 and MJL21196 with .5 ohm emitter resistors if this is ok for the board.
Which would be better-- dual 40VAC or 45VAC secondaries? What would the "missing" resistor values need to be in my case?
I'm thinking of using an Avel xformer at 800 VA to cover both channels. No dual mono for me on this design. Think i'll use MJL21195 and MJL21196 with .5 ohm emitter resistors if this is ok for the board.
Which would be better-- dual 40VAC or 45VAC secondaries? What would the "missing" resistor values need to be in my case?
Jacco,
Have you receive your boards yet?
I am going to use 1000VA 45VAC transformer.
Could the gurus please let me know what the "to be determined" resistors values are?
Have you receive your boards yet?
I am going to use 1000VA 45VAC transformer.
Could the gurus please let me know what the "to be determined" resistors values are?
Sounds like everyone wants the amp to have "balls". Maybe we should have gone for the ten output device version????
LOL I remember I was pushing for the six when some wanted only four outputs.
LOL I remember I was pushing for the six when some wanted only four outputs.
gengis,
got my boards this am, i never expexted it to come as fast! anyway thanks a lot...now on to building amps....
imho it is still possible to do a ten output or more, just copy the output transistor side of the pcb for any number of outptut transistors!
got my boards this am, i never expexted it to come as fast! anyway thanks a lot...now on to building amps....
imho it is still possible to do a ten output or more, just copy the output transistor side of the pcb for any number of outptut transistors!
FYI-
Partsconnexion has their resistors on sale for 15% off until July 31.
Resistor sale
I've still been considering using TO-220 devices as temperature sensors. However, I was not able to locate general purpose diodes in that package. They all seem to be the expensive, ultratrafast type, which is a waste. Then I got to thinking the base-emitter junction of a transistor is basically a diode. Since transistors in this package are commonly available, an there may be many left over after a matching routine, why not use the base and emitter leads, and clip off the collector lead, to make a temperature sensing diode?
Partsconnexion has their resistors on sale for 15% off until July 31.
Resistor sale
I've still been considering using TO-220 devices as temperature sensors. However, I was not able to locate general purpose diodes in that package. They all seem to be the expensive, ultratrafast type, which is a waste. Then I got to thinking the base-emitter junction of a transistor is basically a diode. Since transistors in this package are commonly available, an there may be many left over after a matching routine, why not use the base and emitter leads, and clip off the collector lead, to make a temperature sensing diode?
Glad to hear. Thank the USPS and Global Priority Mail.
As far as # of output devices, I like, quoting the Tool Man,
'More Power.'
Pooge,
Onsemi MSR1560.
10 device boards..
I got my boards a couple of days ago, beautiful.. But maybe a GB of "10 device" boards isn't such a bad idea..
I love DIY but it is downright ugly somtimes. It would look nicer if it was a complete PCB. They where a bit on the expensive side the fist run but only because is was a small series of boards? The price of the output devices and power supply is not that bad when you look at a whole amp.
I would like a higher power amp for my front system and the "Leach Amp" seems to be the right way. No problem, I'm in for six of them if we could reach similar amount and price.. Thanks for now I have to order parts...
Thank you everyone who have helped to realize this GB
Happy DIY, or assemble if you wish..
/Martin Sahlin.
I got my boards a couple of days ago, beautiful.. But maybe a GB of "10 device" boards isn't such a bad idea..
I love DIY but it is downright ugly somtimes. It would look nicer if it was a complete PCB. They where a bit on the expensive side the fist run but only because is was a small series of boards? The price of the output devices and power supply is not that bad when you look at a whole amp.
I would like a higher power amp for my front system and the "Leach Amp" seems to be the right way. No problem, I'm in for six of them if we could reach similar amount and price.. Thanks for now I have to order parts...
Thank you everyone who have helped to realize this GB
Happy DIY, or assemble if you wish..
/Martin Sahlin.
Re: 10 device boards..
Speaking of "more power". I'm still hoping that Jens goes ahead with the Leach Superamp design. I would rather build one of those than the 10 transistor unit.
How about it Jens? Any chance you'll get interested in doing the Double Barrel again?
Blessings, Terry
pool said:I got my boards a couple of days ago, beautiful.. But maybe a GB of "10 device" boards isn't such a bad idea..
I love DIY but it is downright ugly somtimes. It would look nicer if it was a complete PCB. They where a bit on the expensive side the fist run but only because is was a small series of boards? The price of the output devices and power supply is not that bad when you look at a whole amp.
I would like a higher power amp for my front system and the "Leach Amp" seems to be the right way. No problem, I'm in for six of them if we could reach similar amount and price.. Thanks for now I have to order parts...
Thank you everyone who have helped to realize this GB
Happy DIY, or assemble if you wish..
/Martin Sahlin.
Speaking of "more power". I'm still hoping that Jens goes ahead with the Leach Superamp design. I would rather build one of those than the 10 transistor unit.
How about it Jens? Any chance you'll get interested in doing the Double Barrel again?
Blessings, Terry
I like the idea of using TO220 package devices as diodes. It's worked well in the past for me. I always used the B-C junction though; I forgot why. This matches the devices being traced better than the high speed diodes anyways.
mlloyd1
mlloyd1
pooge said:
mlloyd1 said:
Guess we better get that straight. I assumed B-E because Vbe is what is getting tracked in the output transistors.
Re: Re: 10 device boards..
I hope to pick that project up this fall/winter. Right now my house takes all of my DIY time.
\Jens
still4given said:
I hope to pick that project up this fall/winter. Right now my house takes all of my DIY time.
\Jens
If it is possible to have 2 pcb, can terry and jens email me how to order them and to who send my postal address?
Thank's you for your time and job about this project.
Ciao, Giuseppe.
(audiog@libero.it)
Thank's you for your time and job about this project.
Ciao, Giuseppe.
(audiog@libero.it)
MJE340/350
Hi Jens,
Am I correct in thinking that you replaced the 2N3440/2N5416 with MJE340/350?
What is the reason and are they interchangeable?
Can the MJE's be used where the 2N's are called for if the pins are arranged properly?
Thanks, Terry
Hi Jens,
Am I correct in thinking that you replaced the 2N3440/2N5416 with MJE340/350?
What is the reason and are they interchangeable?
Can the MJE's be used where the 2N's are called for if the pins are arranged properly?
Thanks, Terry
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