To call this methodical approach and resulting arrangement "Impressive" would be an understatement of the year.

@bandwidthaudio7479

Жыл бұрын

Thank you! Glad all the effort shows through and these videos.

@2Worlds_and_InBetween

Жыл бұрын

yeah... nice work

The parts and design looks TOP NOTCH!!! I'm still waiting for this amp. :)

@bandwidthaudio7479

11 ай бұрын

Thank you!! Don’t worry, this will be done soon and available for special order. Turning everything into a production ready product is always a variable. We are working on final wood sides which includes templates for production and bucks for our sheet metal vendor.

@klaymoon1

11 ай бұрын

@@bandwidthaudio7479 Great to hear! Hope the launch will be as smooth as possible!

Howdy. Credits to Bandwidth Audio. I really liked the presentation of the EI power transformers. The unavoidable air gaps aspect was new to me. Yes. They fight saturation. I would assume toroid manufacturers test their prototypes with clean 50 or 60 Hz and determine the windings close to saturation. There will be little room for residual DC in the mains. Thanks for the illumination. Regards.

@bandwidthaudio7479

Жыл бұрын

Thanks for your comment! Glad it was informative.

Great insights into EI/Toroid comparison and high voltage build aspects. Thanks from Colorado.

Man, I would love to build 845 monos, I'm so jealous! lol. I wish I could afford the iron.

I agree scaring with many ( often asian ) amplifiers .........most audiophiles have no clue about tube technology but buy those ..............nor transformers. thanks for the upload !

Nicely done on the specs of this OPT. About 15 years ago, I went through 4 iterations trying to make an OPT for a 833 DHT amp I was working on. If I lifted the ground between the in and out, it was a glorious 150 WPC, but the leakage capacitance put 1000 V on the speaker terminals. I think the laminations were about double the size you have.

@bandwidthaudio7479

Жыл бұрын

That's a really big transformer! If only we could leave the secondary floating.... Out of curiosity, I actually have tried loosely holding the secondary at ground potential with a resistor to see if this reduces the effective bridging capacitance. This actually made things worse as the resistor added another pole in the transformer frequency response.

@briandonaldson518

Жыл бұрын

@@bandwidthaudio7479 I can see that. The resistor dissipate energy while opposing the high frequency causing more rolloff that just the capacitance.

@Signal_Glow

Жыл бұрын

Are you writing about lifting the ground connection between OT's pri and sec? Why would you do that if things like galvanic isolation are the reasons for using OTs? I might not understand SE DHT amps because vast majority of my work is pro audio small signal stuff where OT's pri and sec grounds are always separated.

@briandonaldson518

Жыл бұрын

@@Signal_Glow The OPT is a galvanic isolation, but it's main purpose is impedance matching and choke loading. IIRC, it's 5K to 8ohm. The ground is necessary for safety, because without it, the outputs floats to 1/2 B+, around 1000V. But the problem, grounding the speaker ground raises the leakage capacitance 4x, killing the top octave.

@Signal_Glow

Жыл бұрын

@@briandonaldson518 Ok, got it, grounded speaker/load. Similar to small signal circuits like mics, preamps, compressors.

Nice work! What is your expected damping Factor? By the way where do you find capacitors that are negative tied to the case these days? I challenge you to actually test with an ohmmeter. This practice was abandoned capacitor manufacturers with the introduction of computer grade capacitors.

@bandwidthaudio7479

Жыл бұрын

Correct, they are not tied directly to the case but the electrolyte that the capacitor jelly roll "swims in" is always contact with the case. This makes the case effectivity tied to the negative terminal and allows charge transfer to the case via the electrolyte. Exact damping factor will need to be measured but the output impedance should be around 1ohm on the 8 ohm tap without any feedback. FYI damping factor is often misused since the speaker voice coil DCR will dominate. i.e. even with an amplifier with 0ohms of output impedance, the speaker DCR (6-8ohms) will determine the damping of the moving mass (ie the speaker cone).

Dam impressive !

Wow, a herculean design! Of course you are generally correct in you discussion of toroidal vs EI transformers. However companies like Tent Labs and Toroidy make high quality toroidal, SE output transformers, so they must have some way of effectively gapping the cores to take the dc present......

@bandwidthaudio7479

Жыл бұрын

Thanks you! I believe they use a ferrite or other core type made from a slurry of ferromagnetic and non-ferromagnetic materials (like ceramic). This reduces the effective permeability of the core and creates a "distributed" gapping effect. This is used all the time for power electronics. The problem with a power transformer is we want the permeability to be as large as possible to reduce core size. Gapping the core will reduce the effective permeability by at least one order of magnitude.

@mfr58

Жыл бұрын

@@bandwidthaudio7479 Thanks for the explanation.

Collins transmitter was driving a pair of 4-400a modulators from 2 6sj7 preamp tubes. and here we are. 845 and solid state plus el34

Sharp design. Looks great.

@bandwidthaudio7479

Жыл бұрын

Thank you!

You mention the disadvantageous of toroidal transformers, but what about R-core transformers?

What about buzzing in those transformer ? They buzz with signal music