[L0rdGwyn]

Oh, I didn't pick up that interstage meant transformer interstage for some reason. No, mine is cap coupled.

Pretty cool. I imagine your friend could have an amp built by pretty much anybody he wanted to. You'll have to take advantage of the opportunity on this one and get a huge chromed L0rdGwyn badge to slap on the front of it for publicity.

I was thinking I would just have the chassis made in the likeness of my avatar so there is no question LOL JK of course, but I think it will look very nice with what I have in mind.

 

[Zachik]

Your friend is an awesome dude!! Missed him (and his lovely wife) at CanJam couple days ago...

 

[L0rdGwyn]

Your friend is an awesome dude!! Missed him (and his lovely wife) at CanJam couple days ago...

Well hey, this amp might be coming to a post-COVID CanJam near you down the road, perhaps in the year 2029 lol.

 

[whirlwind]

Your friend is an awesome dude!! Missed him (and his lovely wife) at CanJam couple days ago...

Yes he is, and they are running a successful business in hard times.
They deserve it.

 

[L0rdGwyn]

I think a lot of companies are still being precautious and don't want to put their employees at risk, even if it means losing a sale, it's an admirable thing to do.

 

[L0rdGwyn]

Just placed the final parts order for the ZMF 45 amp. Since the cat's out of the bag, here are the major components going in.

Vintage Amphenol Ux4 and 9-pin noval sockets
Vintage fluted bakelite knob (will need to polish that baby up a little bit)
Simpson DC milliammeters
Hammond dual-bobbin filament transformers (for the 45 filaments)
Lundahl LL1649 mains transformer and matching shield
Intact Audio nickel-core interstage transformers, custom for this design
ClarityCap TC 2 series film caps feeding the interstage transformers
Electra-Print low IMD output transformers, multitap for various headphone impedances (300ohm, 120ohm, 32ohm)



I won't bore with all of the PCBs I've made, I'll just say that the input tube heaters, 45 filaments, B+, and bias supplies will all be regulated.

And the tubes.



I'm excited to start building, I think this will be a very special amplifier.

 

[bcowen]

Just placed the final parts order for the ZMF 45 amp. Since the cat's out of the bag, here are the major components going in.

Vintage Amphenol Ux4 and 9-pin noval sockets
Vintage fluted bakelite knob (will need to polish that baby up a little bit)
Simpson DC milliammeters
Hammond dual-bobbin filament transformers (for the 45 filaments)
Lundahl LL1649 mains transformer and matching shield
Intact Audio nickel-core interstage transformers, custom for this design
ClarityCap TC 2 series film caps feeding the interstage transformers
Electra-Print low IMD output transformers, multitap for various headphone impedances (300ohm, 120ohm, 32ohm)



I won't bore with all of the PCBs I've made, I'll just say that the input tube heaters, 45 filaments, B+, and bias supplies will all be regulated.

And the tubes.



I'm excited to start building, I think this will be a very special amplifier.

Wait...the 'ZMF' 45 amp? You can 't let a cat just part way out of the bag. That would defy physics.

 

[L0rdGwyn]

This one isn't for me, it is being built for a friend, a certain friend who also makes bespoke wooden headphones.

Here ya go @bcowen

And here is an actual cat for good measure.



Trust me, this one isn't defying any laws of physics, physics has her very well planted to the ground.

 

[bcowen]

Here ya go @bcowen

And here is an actual cat for good measure.



Trust me, this one isn't defying any laws of physics, physics has her very well planted to the ground.

OK, so I'm a little slow. But looking stupid was worth it for a cool cat picture.

 

[Monsterzero]

Great evening of music...The Allman Betts Band and Blackberry Smoke

Great evening of music...The Allman Betts Band and Blackberry Smoke

Blackberry Smoke makes every evening great! My fav modern band.

#spreadthesmoke

 

[whirlwind]

Blackberry Smoke makes every evening great! My fav modern band.

#spreadthesmoke

First time seeing them live for me....Charlie Starr is a great front man.
At the end The Allman Betts band joined them on stage and they all jammed to Whipping Post.
Blackberry Smoke was on stage for 3 hours total as they played with both other bands besides their own 2 hour set.
I need more days like that

 

[Xcalibur255]

Definitely got the right meters there Keenan. Thumbs up. They're exactly the same as the pair I was trying to get sent to you aside from the scale. I really wish the meters on my amp were 0-50 scale. Since the amp originally had a 2A3 mode I bought 0-100 meters to accomodate the 60mA current of a 2A3 but then that whole feature ended up getting removed from the amp.

Gauges that have unnecessarily large scales are kind of a general pet peeve of mine actually. Like how ALL cars have 0-160 MPH speedometers starting about 20 years ago. Why?

 

[raindownthunda]

Definitely got the right meters there Keenan. Thumbs up. They're exactly the same as the pair I was trying to get sent to you aside from the scale. I really wish the meters on my amp were 0-50 scale. Since the amp originally had a 2A3 mode I bought 0-100 meters to accomodate the 60mA current of a 2A3 but then that whole feature ended up getting removed from the amp.

Gauges that have unnecessarily large scales are kind of a general pet peeve of mine actually. Like how ALL cars have 0-160 MPH speedometers starting about 20 years ago. Why?

What is the purpose of the mA meters? Do different mA values provide meaningful information?

 

[L0rdGwyn]

Definitely got the right meters there Keenan. Thumbs up. They're exactly the same as the pair I was trying to get sent to you aside from the scale. I really wish the meters on my amp were 0-50 scale. Since the amp originally had a 2A3 mode I bought 0-100 meters to accomodate the 60mA current of a 2A3 but then that whole feature ended up getting removed from the amp.

Gauges that have unnecessarily large scales are kind of a general pet peeve of mine actually. Like how ALL cars have 0-160 MPH speedometers starting about 20 years ago. Why?

Thanks, T. The "rectangular" series (which these are) have that vintage look but they are actually new production! Think this design has been made by Simpson since the beginning, I think yours are vintage? There was a lead time of a few weeks, but not too bad.

Totally makes sense that you would have gone with the 100mA meters for the 2A3, but since this amp will be 45 only, 0-50mA is perfect. The tubes will bias at around 34mA, but could be reduced to 30mA or so for tube longevity.

What is the purpose of the mA meters? Do different mA values provide meaningful information?

This is a fixed bias design, meaning the bias of the tubes can and must be manually adjusted via a potentiometer that will mount on top of the chassis. The milliammeters are in series with the tube cathodes, so they indicate the bias current of the tubes. The scale of the meters isn't critical, but it's good to use one of appropriate range so smaller adjustments can be made to the bias point.

 

[Tjj226 Angel]

So, my amp? Interesting.

Though I'm guessing you won't be using the C3g as a driver like mine has, maybe a 6J5? Rectification will probably be different too, not the 6BY5 disaster I signed myself up for. It might be interesting to use the "classic" option here: the 80/5Y3. That's what I wish I had done.

or my first attempt at a 45 for @johnjen. We ended up finding out that the direct coupling sounded a lot better.

I also wouldn’t do tube rectification for a 45. The 45 is so detailed and airy that the voltage sag you can run into with tube rectification kind of detracts from the 45 sound.

There are more exotic ways to rectify a circuit that I have yet to play with that would be even better than either a tube or a diode, such as mosfet rectification. You can even use triodes as rectifiers but idk if there is any real advantage to it