So i would like to ask for a little bit of input if anyone has the time to do so on how to handle the power supply. The project is just a first-try at Full-Tube amps. get some hands-on experience.
I want to build a reasonably simple OTL Headphone amp. A basic triode gain stage + White Cathode Follower. Tubes would be a 6922 for gain, 6h30pi for output. Aiming for plenty of current for a wide variety of headphones. 6h30pi can go up to 50ma continues per anode and max 4W dissipation. So i'm estimating roughly 170-200V 80-100ma. Heaters would be ~2A. Also considering creating a small delayed relay with indicator to keep the output disconnected as the amp heats up which would be drawing up to 100ma from the heater.
I want to use a Hammond Mfg 300 series transformer for power as i can reliably get them nearby, are universal and seem great for being mounted on a black enclosure. that is where my headache begins. There is no ideal choice as i should learn to accept rarely will be. been looking at a few of them, but i need input on what would be wise.
I could go for a transformer like the 369ex(380vac c.t, 75ma) that has more than enough current for the heaters and relay and good voltage headroom on the high-voltage for filtering out ripple, but would have to sacrifice some output power capping idle current at ~35ma per channel.
Could go for a lower-voltage 369BX(300vac c.t, 86ma) with enough current on the high-voltage, but it's 6.3v rail is rated for 2A and idk if it is wise to put nearly 2.1A consumption on that.
On the other side is something beefy like a 370DAX with 520v ct 104ma and 3.5A heater. Seems like a choice for a Tube rectifier such as an EZ-81 which drops quite a bit of the voltage to be more like the EX, but idk if rectifier tubes are still a solid choice. Could go for Solid-State regardless,but then i would be looking at an substantial amount of extra voltage(total nearly 170v) to drop in the filter to get what i want. idk if that is a tad much.
Should i sacrifice power? is dropping so much voltage an idea or excessive? Tube rectification: yay or nay? I'm a bit new to power-supplies and am a little dazed by the many options. any suggestions/insight would be welcome
I want to build a reasonably simple OTL Headphone amp. A basic triode gain stage + White Cathode Follower. Tubes would be a 6922 for gain, 6h30pi for output. Aiming for plenty of current for a wide variety of headphones. 6h30pi can go up to 50ma continues per anode and max 4W dissipation. So i'm estimating roughly 170-200V 80-100ma. Heaters would be ~2A. Also considering creating a small delayed relay with indicator to keep the output disconnected as the amp heats up which would be drawing up to 100ma from the heater.
I want to use a Hammond Mfg 300 series transformer for power as i can reliably get them nearby, are universal and seem great for being mounted on a black enclosure. that is where my headache begins. There is no ideal choice as i should learn to accept rarely will be. been looking at a few of them, but i need input on what would be wise.
I could go for a transformer like the 369ex(380vac c.t, 75ma) that has more than enough current for the heaters and relay and good voltage headroom on the high-voltage for filtering out ripple, but would have to sacrifice some output power capping idle current at ~35ma per channel.
Could go for a lower-voltage 369BX(300vac c.t, 86ma) with enough current on the high-voltage, but it's 6.3v rail is rated for 2A and idk if it is wise to put nearly 2.1A consumption on that.
On the other side is something beefy like a 370DAX with 520v ct 104ma and 3.5A heater. Seems like a choice for a Tube rectifier such as an EZ-81 which drops quite a bit of the voltage to be more like the EX, but idk if rectifier tubes are still a solid choice. Could go for Solid-State regardless,but then i would be looking at an substantial amount of extra voltage(total nearly 170v) to drop in the filter to get what i want. idk if that is a tad much.
Should i sacrifice power? is dropping so much voltage an idea or excessive? Tube rectification: yay or nay? I'm a bit new to power-supplies and am a little dazed by the many options. any suggestions/insight would be welcome
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You might be better off with something from Antek, e.g. AS-05T160, which has 2 6.3V@2A windings and 160V@150mA (with 140V tap). These are AC currents, should be able to get 200V DC @ 100 mA using the 140V tap and solid state bridge rectifier. Then lose 30-40V in filtering. I used a similar 50VA model for my OTL headphone amplifier running 50 mA bias.
Otherwise the 369BX would probably be OK, might run a bit hot.
Otherwise the 369BX would probably be OK, might run a bit hot.
You probably could use one of those. Transfer Multisort Elektronik - On-line catalogus| 250 000 producten in het assortiment , tme is situated in Eindhoven i think.
Or this one from Poland, same brand but isn't on the list of tme.
TSTA 0060/001 - Mains transformer for tubes - Shop Toroidy.pl
Mona
Or this one from Poland, same brand but isn't on the list of tme.
TSTA 0060/001 - Mains transformer for tubes - Shop Toroidy.pl
Mona
Tikiroo: Never heard of antek before. Though they do have a nice lineup of toroidal "low"-voltage, high-current tube amp transformers. Plus the relatively low price compensates for the shipping costs making it an option. Thanks for the suggestion.
Ketje: Not a lot of choice at TME. The polish store seems interesting being still EU so i will check them out.
Lingwendil: Trying to keep transformer count down. Also only Filament supplies/transformers i can easilly source are 115v primaries and not in the dual.
Also i know how to use Tube rectifiers. Not experienced in choosing transformers, but i know of tube rectifier quirks such as limiting anode current and capacitor size in Capacitor input topology and how to estimate drop/sag. I do my research ^^. Just wondering if they still do their job well. Like Life-span wise cause such info is rarely listed on their datasheets.
So far thanks for the help everyone!
Ketje: Not a lot of choice at TME. The polish store seems interesting being still EU so i will check them out.
Lingwendil: Trying to keep transformer count down. Also only Filament supplies/transformers i can easilly source are 115v primaries and not in the dual.
Also i know how to use Tube rectifiers. Not experienced in choosing transformers, but i know of tube rectifier quirks such as limiting anode current and capacitor size in Capacitor input topology and how to estimate drop/sag. I do my research ^^. Just wondering if they still do their job well. Like Life-span wise cause such info is rarely listed on their datasheets.
So far thanks for the help everyone!
Doubt it would work. Tubes shouldn't be run outside of the 10% tolerance. 5 is way to low and might reduce lifespan.
If you are suggesting to rectify 5Vac into 6Vdc. an option, though would have to add very large reservoir capacitors to get something out of it. Also do believe i would risk overloading the transformer as rectified consumption goes up substantially up to nearly 4A.
So far a transformer such as the Antek 05T160 seems most promising.
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So far a transformer such as the Antek 05T160 seems most promising.
Toroidy sadly has no options that would be suitable. at least not without sacrificing power or ending up with large voltages to drop much like the 370DAX.
Hammond 369HX is now also of interest. Bit overkill with the 2 heater rails, but seems flexible enough for me to experiment with.
Toroidy sadly has no options that would be suitable. at least not without sacrificing power or ending up with large voltages to drop much like the 370DAX.
Hammond 369HX is now also of interest. Bit overkill with the 2 heater rails, but seems flexible enough for me to experiment with.
I use a lot of Antek transformers, and have been nothing but pleased with them. I really like them. The only real downside to them (other than lack of 5 volt windings) is that they're ugly
That is 2 people vouching for antek. Think they may be worth the shipping and possibly import tariffs associated.
Yeah that is the only thing i'm wondering about with them. Toroids are great from an engineering p.o.v. so long as you keep in mind the inrush, but they do look like plastic wrapped donuts.
But for that one can use a Toroid Shield i believe. So long as one keeps in mind power dissipation and to avoid it coming in contact with the bolt keeping the transformer in place to avoid a shorted turn. Correct me if i'm wrong though!
A huge amplifier project that I built years ago (seven toroids on the top of the chassis!) Was doomed to be a homely monster until I went down to the hardware store and dug through the PVC/ABS fittings. I managed to find some 3" sewer ABS caps that covered the six 25VA toroids I was using for outputs, and I didn't even need to paint them since they were already black. The monster power toroid (300VA) I managed to hide under a round cheesecake pan after a coat of paint. Nobody knew the sins I had committed unless told by me
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