example recipe when I'm ordering custom Donut from Trafomatic:
********************************
Toroid xformer, 300VA
Primary 230Vac (or 2x115Vac if needed)
2 (two) secondaries of 18Vac each, under nominal load
wound for decreased flux to prevent buzzing - A Class amp, so constant load is 90W
all leads stranded wire, 25cm long, secondaries at 180deg from primary
Static shield, magnetic shield
*****************************
so, please - Boyz at Trafomatic are knowing their ****, no need to contemplate about core size, number of windings etc. - everything stated above is just right for proper order; if you start adding more info, you're just being smarta$$, so better wind your own if you're so smart
********************************
Toroid xformer, 300VA
Primary 230Vac (or 2x115Vac if needed)
2 (two) secondaries of 18Vac each, under nominal load
wound for decreased flux to prevent buzzing - A Class amp, so constant load is 90W
all leads stranded wire, 25cm long, secondaries at 180deg from primary
Static shield, magnetic shield
*****************************
so, please - Boyz at Trafomatic are knowing their ****, no need to contemplate about core size, number of windings etc. - everything stated above is just right for proper order; if you start adding more info, you're just being smarta$$, so better wind your own if you're so smart
Thank you!example recipe when I'm ordering custom Donut from Trafomatic:
********************************
Toroid xformer, 300VA
Primary 230Vac (or 2x115Vac if needed)
2 (two) secondaries of 18Vac each, under nominal load
wound for decreased flux to prevent buzzing - A Class amp, so constant load is 90W
all leads stranded wire, 25cm long, secondaries at 180deg from primary
Static shield, magnetic shield
*****************************
so, please - Boyz at Trafomatic are knowing their ****, no need to contemplate about core size, number of windings etc. - everything stated above is just right for proper order; if you start adding more info, you're just being smarta$$, so better wind your own if you're so smart
Same goes for 130 watts constant load? Or will they suggest 400vA if they think that is proper?
that was my recipe for dual mono
if you want common Donut for both channels, take 400 or 500VA Donut
your choice is are you going for secondary/es common for both channels, or you're going to cheat - having separate second. for each channel
I had 800VA Donut on the shelf, with 4*18Vac secs, and that is in my Papa's Koan
btw. how many VA - that is your choice and reasoning; I just said - do not write tales "how-to", write facts when ordering
if you want common Donut for both channels, take 400 or 500VA Donut
your choice is are you going for secondary/es common for both channels, or you're going to cheat - having separate second. for each channel
I had 800VA Donut on the shelf, with 4*18Vac secs, and that is in my Papa's Koan
btw. how many VA - that is your choice and reasoning; I just said - do not write tales "how-to", write facts when ordering
Damn. This amp is a killer!
Also gotta say positive phase 2hd really has it’s merits. Lightfooted like air, just as advertised
And, «suddenly the fullranges had bass!»
Also, too clean for spooky. But really strikes a nice balance. With an IP in front it’s gotta be close to ideal.
Also gotta say positive phase 2hd really has it’s merits. Lightfooted like air, just as advertised
And, «suddenly the fullranges had bass!»
Also, too clean for spooky. But really strikes a nice balance. With an IP in front it’s gotta be close to ideal.
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Read back over your comments regarding the transformer…triggered my OCD
I couldn’t remember any issue with transformer noise regarding my F2J build. I used Antek AS3218.
However, I’ve been wrestling with a pair of BJ2 amps for a while.
When I built the power supplies Antek had nothing in stock.
I resorted to dual mono Avel-Lindberg 250va per chassis from Parts Express.
I really shot myself in the foot with the build in more than one way…the chassis’ were modeled after a 4U/300. So I’m chasing more dissipation with a fan cooling system to get to higher current.
The donuts already buzz…can’t be heard when the cover is on the amp…still, I wonder if it will just get worse once I try a higher bias setting?
I couldn’t remember any issue with transformer noise regarding my F2J build. I used Antek AS3218.
However, I’ve been wrestling with a pair of BJ2 amps for a while.
When I built the power supplies Antek had nothing in stock.
I resorted to dual mono Avel-Lindberg 250va per chassis from Parts Express.
I really shot myself in the foot with the build in more than one way…the chassis’ were modeled after a 4U/300. So I’m chasing more dissipation with a fan cooling system to get to higher current.
The donuts already buzz…can’t be heard when the cover is on the amp…still, I wonder if it will just get worse once I try a higher bias setting?
If the buzz is current dependant, yes, it will likely. But I have experienced both: a buzzing tranny that buzzes the same no matter what, and this time one that seemingly buzzes more with increased current. I can’t hear mine either, unless I put my ear against the front cover. But what if I am to use more sensitive drivers than now? There is a likely magfield carrying this crappy noise into the right channel now, but one would be hard pressed to hear it (92db sens drivers now).
So I have placed an order for a custom tranny specced for this exact amp @ Trafomatic in Serbia.
I’m actually wondering if these chassis’ and donuts (or a single AS3218) might be better repurposed for a pair of stereo F2J amps.
I could just pull everything from my monoblocks and reinstall them with an additional amp board.
The monoblock supplies can drive two channels (I have them wired in each like a dual/mono supply) and the amps would be used to drive highs and mids for either the left or right channel.
In looking through the specifications at the First Watt site the F2 happens to have the lowest power consumption figure that I can find @150 watts (~75 per channel).
The BJ2 has to be drawing more current even as the bias is currently set.
I have the extra F2 boards and parts.
My goal is to experiment with a variety active multiway combinations once I get a pair of stereo amps sorted and build some new bi-amp crossovers for them.
I could just pull everything from my monoblocks and reinstall them with an additional amp board.
The monoblock supplies can drive two channels (I have them wired in each like a dual/mono supply) and the amps would be used to drive highs and mids for either the left or right channel.
In looking through the specifications at the First Watt site the F2 happens to have the lowest power consumption figure that I can find @150 watts (~75 per channel).
The BJ2 has to be drawing more current even as the bias is currently set.
I have the extra F2 boards and parts.
My goal is to experiment with a variety active multiway combinations once I get a pair of stereo amps sorted and build some new bi-amp crossovers for them.
You could try and disconnect the rails from your amp boards, just to check if it is current or DC pr the combo driving them to saturation or not. Some buzz without load too… and some just don’t…
I saw your amps before. Lovely beasts.
On another note, my untrusty 80’s HP signalgen just blew up, the whole house stinks.
Luckily it did so the very moment the 2J was just set for symmetrical clipping
Impossible for me to advise you, but I let myself get pretty pissed on those sorts of things. Especially when paying for audio grade drek.
I can let you know how my experience with Trafomatic turns out, perhaps something to consider
Some say these sorts of things are to be expected with toroids. Well, I don’t incline to agree, or let me rephrase: I don’t think we should accept or settle for that. Since I have it on good authorities that it is avoidable, but it may mean careful selection and perhaps a but of hit and miss and hit.
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Residual in blue sine @ 1 watt into 8 ohms.
And @ clipping 4,5-5 watts into 8 ohms.
Very much easier for a greenhorn to do these adjustments with the distortion residual under the clipping waveforms.
Ps: 0V37 difference between chans, despite matched R100’s. So might be worth the effort using a scope and, in my case, a 334A.
Excuse the noisy waveforms, they are from my Mac. Since my oscillator blew up.
Damn greenhorns
