thanks for your post
Now I am waiting the second stuff to check the quality with the first and in case do something.
In the little factory there is a beautiful wound machine comes from Switzerland and was property of Da Vinci brand
Regarding the potting I will take note of your consideration; I was thinkin to check one free air and one potted to understand the the specs; there are metal box 13x13x12 cm ready.
In addition there is very good interstage trafo 5:1 for line out and 1:1+1 for p-p drive ( or s.e) with a little irona always nano. Tested very good ( for me)
Then a s.e. for 2A3 / 45 is coming
Ciao
Walter
Walter,
I made a bunch of amps with interstages and if your looking for a little bit of compression that works well. When Avantgarde Horns were selling like hot cakes I made a couple of 300B amps doing that and people loved them.
I make a lot of guitar amps that are PP and use a tapped inductor. Feed the plus signal into the dotted end, ground or bias the CT and the non-dotted end gives you -180 degrees. Plus there is no compression. It sounds simple but a little harder to design than winding equal sides. Plus since the two parts are in parallel the inductance drops.
Don't care for the 2A3, most new ones are just 300B's with the filament in parallel. Old single plates are expensive and gassy now. 45's are so much better sounding and VT52. Just shipped a stereo VT52 with silver outputs 3 weeks ago.
Thanks,
Gordon
I made a bunch of amps with interstages and if your looking for a little bit of compression that works well. When Avantgarde Horns were selling like hot cakes I made a couple of 300B amps doing that and people loved them.
I make a lot of guitar amps that are PP and use a tapped inductor. Feed the plus signal into the dotted end, ground or bias the CT and the non-dotted end gives you -180 degrees. Plus there is no compression. It sounds simple but a little harder to design than winding equal sides. Plus since the two parts are in parallel the inductance drops.
Don't care for the 2A3, most new ones are just 300B's with the filament in parallel. Old single plates are expensive and gassy now. 45's are so much better sounding and VT52. Just shipped a stereo VT52 with silver outputs 3 weeks ago.
Thanks,
Gordon
Potting will change the sound, the potting compound type will also affect timbre, but overall we have subjective preferences for many types of sound. So I see nothing wrong with both options.
Crystal-containing core materials* are notorious for their degradation in terms of permeability when they are potted. A brand like Vacuumschmelze noted up to 30% less permeability in their technical bulletins. A brand like Tribute audio potted all their transformers, maybe another brand did too.
As far as I know, amorphous materials don't have such "problems" and neither do nano crystalline materials (or very few)
* all traditional core materials as SiFe or nickel iron (permalloy/mumetall). They suffer from stress.
As far as I know, amorphous materials don't have such "problems" and neither do nano crystalline materials (or very few)
* all traditional core materials as SiFe or nickel iron (permalloy/mumetall). They suffer from stress.
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I haven't experienced anything like this, however my potting compounds are a bit mushy in density due to additives and they probably do not compress the core to a critical extent.
Sockpuppet account of previously banned member has been deactivated.You don't need to pot transformer with epoxy or silicone, just impregnate them with varnish. Its enough to fix winding and core lamination, and protect them vs moisture.
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Mike LaFevre use to pot them with bees wax. Low temp for outputs and high temp for power transformers. Said it always sounded better. On the less expensive stuff he would water down lacquer and use that.
New entry as proto.
300B p-p nano
Ratio: 28:1
secondary fixed at 5 ohm
Freq. resp.
backward method; 100 Vrms on 2 kohm ( half of the nominal impedance, arbitrary choice) on primary acting as secondary; 5 watt rms.
Pair
Phase
300B p-p nano
Ratio: 28:1
secondary fixed at 5 ohm
Freq. resp.
backward method; 100 Vrms on 2 kohm ( half of the nominal impedance, arbitrary choice) on primary acting as secondary; 5 watt rms.
Pair
Phase
Forgot to list the electric specs for 300B p-p
Rdc primary = 60 ohm
Rdc secondary = 100mohm
Lprimary = 140 H at 120 hz
Lsecondary = 180 mH
Walter
Rdc primary = 60 ohm
Rdc secondary = 100mohm
Lprimary = 140 H at 120 hz
Lsecondary = 180 mH
Walter
100Megs on a transformer winding? It's an open circuit. 100milliohms on a transformer winding? It's likely a short circuit in most settings.
Call me an a**hole, but I highly suspect such posts as insulting trolling attempts. I've been following member @waltube 's posts and although there are details of his work where we differentiate, I'd say he's enough of a skilled and talented builder to make a difference between an open circuit secondary and an appropriate valued ohmic loss value (for a 5 Zout secondary winding).
Do I imagine things, or transformer builder discussions tend to burst into ambiguous attacks derived from potentially fragile egos?
Never had any intention of being so impolite, as I have never used the A-word toward anyone on this site. If it seems that I implied such a response, then I apologize; that was never my intention.
Walter,
Are you sure that operating point (voltage) values are OK?
Trioded E810F ordinary operating points at about 150V, about 20mA, about -2 .. -2.5V.
240V is too much.
Are you sure that operating point (voltage) values are OK?
Trioded E810F ordinary operating points at about 150V, about 20mA, about -2 .. -2.5V.
240V is too much.
I have checked from 150 to 240 Vdc; of course it is an hard point ( normally I go close to 100% of dissiaption)
This setting seems to be fine. The Pa is within spec
The Rk is 200 ohm
Vin is 500 mV
With 1 Vin, I got around 47 Vrms out with 1,5% THD
Walter