I built this one stereo (single ended version). It has two 600 va transformers, separated power supplies. It is extremely heavy, have not weighed it, but sure its over 100lbs. Sounds better my other Passdiy amps. That Is a BA3 gain stage on top, I no longer use it, turns out I dont need it.
If I remember correctly, it has +/- 25 volt rails, and I think it clipped 8 ohms at 14 watts.
btw, I have 1500va 40vpar/80vser hammond for sale if your interested, I thought that I would make an F5T with it someday.
cheers
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Very nice build!!!
Thank you for the offer but I think the shipping cost to my place would be tooo much...
I am trying to find something locally...
Guys, what type of resistors are you using for source resistors on MOSFETs? Is it ok to use metal film also? Otherwise I cant source 3W metal oxide lower values then 1R. Other problem is Mundorf 5W dont fit on the PCB...Any thoughts?
metal oxide tolerate overload a bit better than metal film.
For source resistors I would use either metal wire or metal oxide, not metal film.
Except that the latest I am working on uses 5off parallel 1r0 600mW 1% metal film to give an equivalent to 0r2 3W 1% metal film as an emitter resistor. So I break my own rules. The emitter resistors of the 2pair output stage, have a no overload current limit of >7.7A
For a fast transient I would expect them to tolerate ~15Apk provided the transient is very short. 15Apk is my target for peak transient current for a 100W into 8ohms capable amplifier.
For source resistors I would use either metal wire or metal oxide, not metal film.
Except that the latest I am working on uses 5off parallel 1r0 600mW 1% metal film to give an equivalent to 0r2 3W 1% metal film as an emitter resistor. So I break my own rules. The emitter resistors of the 2pair output stage, have a no overload current limit of >7.7A
For a fast transient I would expect them to tolerate ~15Apk provided the transient is very short. 15Apk is my target for peak transient current for a 100W into 8ohms capable amplifier.
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Sitting here, ordering parts for my BA-3 build, wondering what resistors it would be worth spending a bit more on, and which ones are not that important. I understand that the ones in the "signal path" are the ones that mostly matters. But the more I'm trying to figure out which ones that could be, the more unsure I get...
I've been reading all papers, and quite a bit of threads, about the BA's several times but realize that I'd mostly be guessing if I made any decissions based on what I understand... :/
Any help or suggestions would be highly appreciated!
//Ronny
I've been reading all papers, and quite a bit of threads, about the BA's several times but realize that I'd mostly be guessing if I made any decissions based on what I understand... :/
Any help or suggestions would be highly appreciated!
//Ronny
Any resistor you choose won't have as much impact on the sound as 1 turn of P3...
Use 1% metal films and don't worry. The 3W are hard to find in 1%, 5% is fine there.
Use 1% metal films and don't worry. The 3W are hard to find in 1%, 5% is fine there.
I've also been wondering about which chassis to choose. When I first started I planned to build the F5 Turbo, and ordered 24 volt toroids, but then changed my plans. Is there any point in using the 5U chassis instead of the 4U for the BA-3, regarding how high I can turn up the bias, or are the number MOSFETs the limiting factor? (I'm using the standard output boards from the store, total of 12 MOSFETS.)
//Ronny
//Ronny
Ronny,
I am also in process of building it. For the front end I ordered carbon composition resistors and for the
F4 metal oxide and on gates carbon composition...The bias board consists of metal film!
I find the carbon good, like in good old days in mcintosh amps...🙂
I am also in process of building it. For the front end I ordered carbon composition resistors and for the
F4 metal oxide and on gates carbon composition...The bias board consists of metal film!
I find the carbon good, like in good old days in mcintosh amps...🙂
has someone give a thought to replace the coupling cap between the front end and F4 whit a transformer?
I have found the mod from ZEN! Great, removing C3 and installing Cx capacitor looks very nice...
Today I finished the ZEN mode, looks great! Two big silmic 2 capacitors on bias board...🙂
Cant wait to hear it in action...
Cant wait to hear it in action...
