Yes it will be, without modification, but in the end its not worth it with that low of voltage. Search up transformer unwinding that will be your best option if you plan on reusing.
Counter-winding cost practically nothing to try, all you add is li'l extra series resistance (if you have open center toroid) If it becomes a mind sore you can address it later. You probably can't pull more current in exchange for the lower output voltage because the wires/core inside are dimensioned for higher voltage VA's. I'll agree it might potentially be a future extra cost if you can't stand it.
I have done counter winding with no noticeable side effect, though not for audio applications.
A stereo pair of EF3-3 will draw a bit over 0.6A quiescent current, the output voltage at that current is of more use when deciding if it's possible to reuse the old transformer.
Having said that, considering the total cost of the project, I would buy a new one, certainly no counter winding.
Might be a stupid question but:
C115/117, witch values are preferred?
I did see sheet#3 in the BOM with all the data, but do not know the use of these.
So a small guide would help me alot🙂
Regards
C115/117, witch values are preferred?
I did see sheet#3 in the BOM with all the data, but do not know the use of these.
So a small guide would help me alot🙂
Regards
Not a stupid question, you can use the largest capacitance and lowest ESR which will fit and also have enough safety margin for the power supply rail voltage you are using.
- hope this helps
- Dan
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Started the unwind of the transformer.
Luckily it's not molded.
My priority is best possible sound, and secondly high power.
Should I go for EF3-4 and 70VDC?
Luckily it's not molded.
My priority is best possible sound, and secondly high power.
Should I go for EF3-4 and 70VDC?
Why ? I had one builder with 87V rails (slewmaster) , he used an old 1KVA isolation trafo (60-0-60)... Worse case you would lose a little SOA but have lots of headroom ! 100V caps all around.
You could also change the resistor ratio on the cap multipliers to drop the IPS voltages.
I personally ran my Slewmaster with 52-0-52 and 75V rails ... no issue whatsoever.
Be careful - those are deadly voltages !
OS
Personally I would play it safe, I wouldn't compromise the SOA. A transformer with 50-0-50 would be my max. for this amp, especially when using 4 ohm, 60 degree speakers. Jeremy created a spread sheet that clearly shows the SOA limits for various output transistors.
The Slewmaster amp has an extra output pair and larger driver transistors. Many of the Slewmaster builders used the Sanken output transistors (including myself) which increased the SOA and could go to higher rails.
The Slewmaster amp has an extra output pair and larger driver transistors. Many of the Slewmaster builders used the Sanken output transistors (including myself) which increased the SOA and could go to higher rails.
I suppose you are right if one runs 100's of watts (for hours) on the test bench. In real life use , I doubt there would be an issue.
SOA sucks with DC. At 20hz , the "10mS" graph would apply.
I do like lower voltages , my pair of Wolverines will be bridged 53V rails running a KW sub. "Wolverine abuse" he he,,,
OS
SOA sucks with DC. At 20hz , the "10mS" graph would apply.
I do like lower voltages , my pair of Wolverines will be bridged 53V rails running a KW sub. "Wolverine abuse" he he,,,
OS
Is the EF3-3 v4.0 the 1st GB boards?
Edit: Nvm, I see in the schematics that the 2nd GB is the v4.0 boards. I'm just curious where I can find info on the the updates for the v4.1 boards I see in the build guide.
While my IPS v3.8 boards are about halfway done, I've not yet really got started in earnest on stuffing the EF3 boards -- I'm wondering if I ought to just place an order for just the v4.1 EF3-3 boards since I need to also place an order for the new bias resistors/Q103,104.
Edit: Nvm, I see in the schematics that the 2nd GB is the v4.0 boards. I'm just curious where I can find info on the the updates for the v4.1 boards I see in the build guide.
While my IPS v3.8 boards are about halfway done, I've not yet really got started in earnest on stuffing the EF3 boards -- I'm wondering if I ought to just place an order for just the v4.1 EF3-3 boards since I need to also place an order for the new bias resistors/Q103,104.
question on R6 (43k) resistor - no mention like other resistors in THE BOM it needs to be 1/2w, but the parts listed are 1/2w. I have 1/4w on hand, so I want to make sure I'm not setting myself up for a failure using a lower wattage part?
Can I use 1/4w or do these need to be 1/2w? Also in the process of a c4793/a1837 conversion to MJE drivers.
Ohms law calculator is giving me 110mW, assuming 68V across 43k at ~1.6mA - so I think I'm good with 1/4w resistor, but can anyone confirm for me?
Can I use 1/4w or do these need to be 1/2w? Also in the process of a c4793/a1837 conversion to MJE drivers.
Ohms law calculator is giving me 110mW, assuming 68V across 43k at ~1.6mA - so I think I'm good with 1/4w resistor, but can anyone confirm for me?
You see, you play it safe but still you go for enormous headroom for home listening. Of course, you accept increased price for such solution.
Headroom and speed make amps more enjoyable devices when listening to music. On some good recordings the difference between the average and peak can approach 30dB and then some transients require high speed. That's why Stochino (SR 300V/us) sounds better on some material than slower but very low distortion amps.
cheers,
The boards that were released for the 1st GB were.
V3.9 for the Precision EF3-3 & EF3-4 output stage boards.
V3.7 for the Wolverine IPS boards.
The boards that were released for the 2nd GB were.
V4.0 for the Precision EF3-3 & EF3-4 output stage boards.
V3.8 for the Wolverine IPS boards.
Version V4.1 of the Precision EF3-3 & EF3-4 output stage boards are still work in progress.
Version V4.6 for the Wolverine IPS boards are also work in progress.
These will be tested thoroughly and reviewed in due time.
I'll update the images in the build guide. Sorry for any confusion 🙂
Good Luck with the Build