Hi James and Enzedone, sorry I missed your replies, I have never used RS Components, allways thought they were too expensive, might give them a try.
My aleph 2's use Harbuch, they seem ok but they tend to hum a bit, having said that I didnt buy their audio range which are quite spendy. A friend used their audio range on his aleph 2's and from memory he gets hum too.
Check
I'm not too good with this sort of thing. So I would really appreciate it if someone more knowledgeable than me could have a look at this.
It's not perfect but the scale is right for the parts I have.
Please excuse the dodgy parts lay-over, but this was drawn up with windows 'paint' so all those white bits where the component names are won't actually to be kept.
This circuit was originally laid out by 'SP'
I'm not too good with this sort of thing. So I would really appreciate it if someone more knowledgeable than me could have a look at this.
It's not perfect but the scale is right for the parts I have.
Please excuse the dodgy parts lay-over, but this was drawn up with windows 'paint' so all those white bits where the component names are won't actually to be kept.
This circuit was originally laid out by 'SP'
Attachments
This question might already have been asked but this thread is 79 pages long so...:
Has anyone done a slightly smaller version of this amp?
I´m asking because I have a 2x15V 300VA transformer, heatsinks, caps and a bunch of 2SK170BL/2SJ74BL.
I´ve read that the mosfets works better with at least 25V rails but how important is that?
Ideally I would like to build a four channel version, my heatsinks could take the heat but the transformer might be right on the limit
assuming +-20V rails and 1A bias.
Perhaps IRF640/9640 would work as output devices?
Has anyone done a slightly smaller version of this amp?
I´m asking because I have a 2x15V 300VA transformer, heatsinks, caps and a bunch of 2SK170BL/2SJ74BL.
I´ve read that the mosfets works better with at least 25V rails but how important is that?
Ideally I would like to build a four channel version, my heatsinks could take the heat but the transformer might be right on the limit
assuming +-20V rails and 1A bias.
Perhaps IRF640/9640 would work as output devices?
Fuling said:
I'm doing it right now - recycling the old Mini-Aleph. Rails are +/- 17V with 1.3 A bias. Transformer is exactly like yours - 2x15 VAC/300 VA followed by two bridges (made of MUR840 diodes) and CRC filter with 80.000 uF per rail. The amp and PSU are behaving very well. It's not finished because I need to make another PCB layout (it's case and heatsink dependent). I tested with p2p made circuit and my main object was the PSU's adequacy. When I complete this Mini-F5 I'll be able to tell you more - a real comparison with standard F5.
The new PCB (105 x 25 mm) should look something like this (bottom view; thanks Goffe
):Attachments
More power
Hi I am new to this thread. I just wondering if we can increase the number of output devices (irfp) to four per channel for more final power. Of coarse we have to alter a little bit the current limiting circuit (reduse the 150 ohm resistor), double the heatsinks and increase the trafo power. Did anyone tried that? If yes what was the results? I already purchased all the parts to do this modification. But it will take a long time until it finishes due to case modifications
Hi I am new to this thread. I just wondering if we can increase the number of output devices (irfp) to four per channel for more final power. Of coarse we have to alter a little bit the current limiting circuit (reduse the 150 ohm resistor), double the heatsinks and increase the trafo power. Did anyone tried that? If yes what was the results? I already purchased all the parts to do this modification. But it will take a long time until it finishes due to case modifications
Re: More power
But then, why not go for a power amp that has already the required (more power in this case) say... Aleph 5... ? I'm about to build one, already have the F5 and would not attempt to get more by doing mods on it. That leads into experimenting, and it's something you might want to do, but then, why get satisfied with just more power output? Why not improve it's weakness, low gain? But do not ruin the perfectly well designed amp with all the improvements you might want to add to it...
kzeprf22 said:
But then, why not go for a power amp that has already the required (more power in this case) say... Aleph 5... ? I'm about to build one, already have the F5 and would not attempt to get more by doing mods on it. That leads into experimenting, and it's something you might want to do, but then, why get satisfied with just more power output? Why not improve it's weakness, low gain? But do not ruin the perfectly well designed amp with all the improvements you might want to add to it...
Re: Re: Re: More power
I think you mean to increase output current, not output power. In that case you could parallel two F5's per channel.
You could even, (if you want more power too) go BPA. Parallel two pairs, and bridge those pairs! That would be a strong fellow Could be done nearly without fiddling with the original circuit.
kzeprf22 said:
I think you mean to increase output current, not output power. In that case you could parallel two F5's per channel.
You could even, (if you want more power too) go BPA. Parallel two pairs, and bridge those pairs! That would be a strong fellow
Could be done nearly without fiddling with the original circuit.Re: Re: More power
The more output devices will add more power drive capability. It will not ruin any of the sonics. Thats why I am telling no more modifications, just drive capabilty. And yes a little bit gain playing with the jfet transistors. By the way das anyone increased the gain to this amp with desirable results?
stein2 said:
The more output devices will add more power drive capability. It will not ruin any of the sonics. Thats why I am telling no more modifications, just drive capabilty. And yes a little bit gain playing with the jfet transistors. By the way das anyone increased the gain to this amp with desirable results?
Re: Re: Re: More power
I have built the NS10 clone to get enough gain. Appeared to be easier and with predictable results. And FYI I have a pair of ESL with a nasty impedance curve, doesn't seem to do any damage or problems to the F5. Of course, if you think you will do better with more ODs, good luck
kzeprf22 said:
I have built the NS10 clone to get enough gain. Appeared to be easier and with predictable results. And FYI I have a pair of ESL with a nasty impedance curve, doesn't seem to do any damage or problems to the F5. Of course, if you think you will do better with more ODs, good luck
more voltage gain
Hi again, is it is advisable to increase the gain of the amp to lets say 11 for 5,7. I mean do we sucrifise something by doing this? I 've done the simulation with spice and I found no problem in bandwith etc. Also I done the change in my F5 by replacing the 10 ohm resistors to 5 ohm. The Amp has more gain ~11, and I didn't noticed any auditable change in my ears. Has anyone knows anything on this? For input jfets I have k170 and J74 bl. Do we limit the prformancr of the Jfets. Any thoughts?
Hi again, is it is advisable to increase the gain of the amp to lets say 11 for 5,7. I mean do we sucrifise something by doing this? I 've done the simulation with spice and I found no problem in bandwith etc. Also I done the change in my F5 by replacing the 10 ohm resistors to 5 ohm. The Amp has more gain ~11, and I didn't noticed any auditable change in my ears. Has anyone knows anything on this? For input jfets I have k170 and J74 bl. Do we limit the prformancr of the Jfets. Any thoughts?
