I see three corrections: also R7/C6 and C7/R10. I will try the Zobel. Indeed, sibilance I didn't call it (yet), but a slight over excited capability to present the high tones. I was pondering changing the feedback loop a bit with the intent the phase will change, but this is much simpler!
Would the slightest coil in the output help? Transitor outputs have that a lot. Just to force compliance into the Zobel, I could understand. With my 4/8ohm non-inductives my F5 build goes flat to above 5 MegaHerz!!!!!
. . [I don't have that in my F5. I was prepared to butcher the F5 . . .]
Long live the F5! How many more iterations can be squeezed out of that topology 🙂
The F5 Twighlight Zone Edition sounds very intriguing. I will take one of each. ha ha
Cambe, the F7 is supposed to have 14dB of gain. Most preamps will work with that just fine. The Iron Pre is a great preamp. Depending on how deep you want to go with it, there is the Iron Pumkin as well which is really neat. More of an investment.
Tube preamps are really nice as well but really only if your amp/speaker combo sounds to sterile and dry for you which I assume it isn't. The Iron Pre and Iron Pumking will do more to preserve the signal.
The F5 Twighlight Zone Edition sounds very intriguing. I will take one of each. ha ha
Cambe, the F7 is supposed to have 14dB of gain. Most preamps will work with that just fine. The Iron Pre is a great preamp. Depending on how deep you want to go with it, there is the Iron Pumkin as well which is really neat. More of an investment.
Tube preamps are really nice as well but really only if your amp/speaker combo sounds to sterile and dry for you which I assume it isn't. The Iron Pre and Iron Pumking will do more to preserve the signal.
I'll try this preamplifier... https://www.diyaudio.com/community/...c85-6922-6dj8-etc-mu-follower-or-srpp.388295/
Attachments
https://www.aliexpress.com/item/1005008666061653.html
This box is very affordable. I would do an F7 or something similar with a +/- 24VDC supply and a smaller quiescent current of up to 0.7A. 8W/8ohm class A and others up to 20W class AB. I don't know if there is enough heatsink for that?
This box is very affordable. I would do an F7 or something similar with a +/- 24VDC supply and a smaller quiescent current of up to 0.7A. 8W/8ohm class A and others up to 20W class AB. I don't know if there is enough heatsink for that?
https://www.aliexpress.com/item/100...cda2b8944128c1fd0994440ac14&afSmartRedirect=y
Full link, 49 available. 😁
It's a small box, but it can fit the F7 somehow. I don't want a big amp, and it doesn't have to be all 20W in A class. 5W class A is enough. I'm not that much of an audiophile. 🤣
External dimensions: width 320mm Height 80mm Depth 331mm
Internal dimensions: Width 250mm Height 74mm Depth 320mm
Material thickness:
Panel thickness: 8 mm
Rear panel: 3 mm
Upper and lower covers: 3 mm
weight：4.7kg
If I succeed in what I'm planning, this will be a tweeter or midrange amp only. I have a much more powerful device for bass.
Full link, 49 available. 😁
It's a small box, but it can fit the F7 somehow. I don't want a big amp, and it doesn't have to be all 20W in A class. 5W class A is enough. I'm not that much of an audiophile. 🤣
External dimensions: width 320mm Height 80mm Depth 331mm
Internal dimensions: Width 250mm Height 74mm Depth 320mm
Material thickness:
Panel thickness: 8 mm
Rear panel: 3 mm
Upper and lower covers: 3 mm
weight：4.7kg
If I succeed in what I'm planning, this will be a tweeter or midrange amp only. I have a much more powerful device for bass.
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The Lateral MOSFET transconductance drops like a rock with decreasing current. This affects the OLG quite a lot, you may lose 6-10dB of the already very low OLG and have problems when applying positive feedback - there's simply not enough gain to stabilise both loops sufficiently under a very low bias. I learned this the hard way with a 650mA (~8W) version of this amp.
Good luck, though. I hope you find a solution.
Good luck, though. I hope you find a solution.
In that case, Houston, we have a problem. 🙄
Another option for a smaller box is active cooling, tunnel like heatsink and super quiet fan. I haven't nailed down anything yet, all options are open. Of all I have only mosfets, fets and PCBs for F7 and PSU. Everything else is subject to change until purchased. The only thing I don't want is a huge box.
Another option for a smaller box is active cooling, tunnel like heatsink and super quiet fan. I haven't nailed down anything yet, all options are open. Of all I have only mosfets, fets and PCBs for F7 and PSU. Everything else is subject to change until purchased. The only thing I don't want is a huge box.
You could use a fan table.
Basically a table on which the amp sits (or sits on top of the amp, your choice) which has some quiet Noctua fans - 7V will get them to inaudible levels - positioned just above or below the heatsink. You can basically run full bias with this setup in those cases all day, every day.
Basically a table on which the amp sits (or sits on top of the amp, your choice) which has some quiet Noctua fans - 7V will get them to inaudible levels - positioned just above or below the heatsink. You can basically run full bias with this setup in those cases all day, every day.
I know that, but I didn't know that lowering the current from 1A to 0.7A would have such dramatic consequences. My friend has a Hiraga really big amp, I didn't notice any consequences with a 30% reduction in quiescent current, although there are BJTs. It was too hot, he had to save it. It sounds the same as before, it's just tolerably hot now.
BJT's have significantly higher "gain" than Laterals, and respond differently.
The best way for you to figure out the solution is to run the simulation yourself. It's not pretty below about 800mA and it's best to use a more traditional drive circuit with higher internal gain. Each stage can be degenerated to get back to the ~32-35dB gain this circuit has at full bias. Positive feedback in small amounts 'can' then be applied around the loop, if you know what you're doing.
I think such a circuit was published in this sub-forum to allow replacement of the Toshiba JFETs with more modern versions (that have lower internal gain). It shouldn't be too difficult to adapt that circuit here.
The best way for you to figure out the solution is to run the simulation yourself. It's not pretty below about 800mA and it's best to use a more traditional drive circuit with higher internal gain. Each stage can be degenerated to get back to the ~32-35dB gain this circuit has at full bias. Positive feedback in small amounts 'can' then be applied around the loop, if you know what you're doing.
I think such a circuit was published in this sub-forum to allow replacement of the Toshiba JFETs with more modern versions (that have lower internal gain). It shouldn't be too difficult to adapt that circuit here.
nixie, have a look at this ALI- box: it has large radiators of >2kg. And the fins are spaced 1cm apart such that it is easy to tap the holes in the DIY-spacing. 2Amps/24V will go per side.
it is not big enough for a LeMonstre (the caps would stick out a cm almost ) but an F7 would go - specifically laterals have some tolerance for heating.
it is not big enough for a LeMonstre (the caps would stick out a cm almost ) but an F7 would go - specifically laterals have some tolerance for heating.
Thanks but the only thing I don't want is a huge box. So I have to go for active cooling to achieve that.
PS
The seller does not ship that box to Serbia, and I know why. Postage, customs, VAT and other costs far exceed the value of that box. This is just a problem that we often face, that the value of goods is much lower than other costs.
The seller does not ship that box to Serbia, and I know why. Postage, customs, VAT and other costs far exceed the value of that box. This is just a problem that we often face, that the value of goods is much lower than other costs.
I have my Hiraga 8W LeMonstre in an even smaller box than you and it has the active Hirage power supply . . . [Currently in the living room even. Comfortably, small, I do understand.]
I want to make new speakers, active. It makes no sense for the tweeter amp to be bigger than the other two. 😵
Otherwise, I plan to try first the F7 improvisation with the SJ50/SK135 on some old heatsinks with a fan. I have two bench SMPS supplies adjustable from 0-45V&4A for testing. If it turns out well, I'll go for the full option with Alfets in a nice box and a quality power supply.
Otherwise, I plan to try first the F7 improvisation with the SJ50/SK135 on some old heatsinks with a fan. I have two bench SMPS supplies adjustable from 0-45V&4A for testing. If it turns out well, I'll go for the full option with Alfets in a nice box and a quality power supply.
It remains an interesting idea to evolve the F5+laterals.
Just plain laterals, naked, I'ld call it a standard F5 . The advantage already is a different power drive. And a slight impact on the harmonics (but it stays cero).
The inventions can go on.
With a further sophistication of the input, such as with a cascode input to grab the harmonic signature of the input jFETs in line with your H2 generator.
And one might even think of a Sziklai driving stage. It really pushes the output out from a voltage reference into the current drive domain.
So that is an interesting thought . . .