K&D,
My take on the V2 version I built (The V3 so far only has one output) at 30V was likely much what Nelson stated (I believe). It's a bit relaxed compared to standard F5 - maybe a little less zazz, but more authoritative for sure. Clean and pure sounding, very resolving. The F5 is still a staple AMP I listen to - it sounds good with a woofer, tweeter or mid range, can drive them all. I will be using it in the end to drive 4 OB woofers. I will see if it can outshine the 50V Cascoded BA-2 with 12 outputs a channel I am using now.
My take on the V2 version I built (The V3 so far only has one output) at 30V was likely much what Nelson stated (I believe). It's a bit relaxed compared to standard F5 - maybe a little less zazz, but more authoritative for sure. Clean and pure sounding, very resolving. The F5 is still a staple AMP I listen to - it sounds good with a woofer, tweeter or mid range, can drive them all. I will be using it in the end to drive 4 OB woofers. I will see if it can outshine the 50V Cascoded BA-2 with 12 outputs a channel I am using now.
I tend to agree. Between the Alephs, the resolution faded with the added output devices.
The Aleph 4 is a stunning bit of kit. Is it worth another £600 to try to better it. I'm not convinced yet.
The Aleph 4 is a stunning bit of kit. Is it worth another £600 to try to better it. I'm not convinced yet.
Any idea where to purchase small quantities of Belleville spring washers at a reasonable price? Everything I can find has a minimum order of around $30-$40.
so where are we regarding heatsinking of the diodes?
main heatsink, or external?
i guess external heatsink let you up the bias some more before the diodes starts conducting. f.ex a 1"long heatsink across the diodes.
main heatsink, or external?
i guess external heatsink let you up the bias some more before the diodes starts conducting. f.ex a 1"long heatsink across the diodes.
. I agree with Tea about the sound. The F5T is a full capable amp, top to bottom. Beyond it, it's not about performance but taste. When I figure this diode thing out, I will be tryin on BA3
For me, seperate heatsinks.
For me, seperate heatsinks.
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In my test, with probably 3-5W heatsinks, driving a 10V square wave certainly heats the FETs, but not so much the diodes. I think source resistor voltage was .6v
This doesn't answer what is the smarter way to do it, have them conducting earlier if pre-warmed on sink.
At some point I will try to do a SINE wave test at 20hz across a 1 or 2R power resistor and see what it does. This will likely be more realistic. I have some ancient stereophile CD with these tones on them.
Buzz,
Which Maggie do you have?
I'm using 3.6's driven by AX100J's. Although I really like the sound I'm getting, you guys are starting to make me wonder, in an expensive kind of way, how an F5T would compare.
Let me say that I appreciate the encouraging way you all are sharing your results. Great work!
Graeme
Which Maggie do you have?
I'm using 3.6's driven by AX100J's. Although I really like the sound I'm getting, you guys are starting to make me wonder, in an expensive kind of way, how an F5T would compare.
Let me say that I appreciate the encouraging way you all are sharing your results. Great work!
Graeme
Another approach I saw in one of the threads is to attach the TO-220 device to a TO-3P sized (or larger) copper plate using solder or Arctic Silver, which is then attached to the heatsink with an insulator. This might provide better thermal performance than clamping with a bar. Can anyone comment on this approach?
You're forgetting that once the case is closed, ambient temperature inside goes up, and so does diode heatsink temperature.
Suppose that the diodes would be on the main heatsink, and diode die temperature would be at 50C : Vf of ~0.500
Suppose that the diodes are on a separate heatsink, die temperature at 40C : Vf of ~0.515
Diddly squat difference.
(pff, headache makes for lots of editing)
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well. then i go for diodes on the main heatsink. voltage drop over source resistor of 0.3-0.35V and +/-42V rails.
I think you could be right. I see all kinds of exuberance towards getting the thing going but only as a huge power amp. Not as an F5 with lots of head room for transients???
I'm not focusing on F5T or F5X right now so I'm just keepin up and helping when I can... Well, that was wrong. I am focussining on my original F5 for Low Z Loads ,. I guess that should be the F5T ver1??? Bein's I was there first, at least on this forum, I have trouble thinkin I'm on the same bandwagon as this thread???
http://www.diyaudio.com/forums/pass-labs/182966-f5-low-z-loads.html
3d option is to mount the diodes on a separate heatsink, which is connected to the main heatsink.
Yes.
I'm thinking balanced, 8 output transistors per quadrant, and 3 cascoded JFET's to drive them. V+ and V- would be about 35-38V, .5 amps bias per output transistor for 200W+ class A power into 8 ohms.
No diodes and more than enough peak current for Maggies. (plus lots of heat)
Graeme
I'm thinking balanced, 8 output transistors per quadrant, and 3 cascoded JFET's to drive them. V+ and V- would be about 35-38V, .5 amps bias per output transistor for 200W+ class A power into 8 ohms.
No diodes and more than enough peak current for Maggies. (plus lots of heat)
Graeme
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i can't see any advantage over eksternal or main heatsink🙂
external sink therm coppled to the main sink is the same as just using the main sink. if its not therm coppled to main heatsink, its just a external heatsink🙂