Univox U-45

[sepulchre]

Yes, mine had a Jensen Special Design speaker. Sounded great.

My research has shown several Lafayette examples of this and they could probably be found here or there. But I want to build one anyway, though the iron alone will cost $100 it turns out. But that's okay, I've got just about everything else.

I started a cab for it last night. At 7.5" high, a foot wide and 8" deep it'll be a cute little booger.

[sepulchre]

After a couple of tries I came up with this layout. Looks a little scrambled but I couldn't see a way to clean it up any more. Using the 12AX7 as both preamp section 1 and the tremolo (at the other end of the board) makes for one stretch. And using the triode/pentode 6BM8s also throws more tangle into the mix.

[Stevem]

Its a low gain amp, that layout should be fine.
If you have the room adding a 3 position rotory switch in the first gain stages cathode to have different values of bypass caps is nice to have in this amp.

[sepulchre]

Actually, the original had neither Rk nor Ck on the first stage. I was considering putting a switch on what I added there but a rotary would be even better.

Also, getting others' eyes on this has helped. Someone suggested that I move the tremolo over to between the first preamp stage and the rest.
ie:preamp, tremolo, preamp, PI, power. Makes sense to me - shorter wires all around.

Thanks!

[Stevem]

yup, that's a good move!

[sepulchre]

Okay, this has taken on a life of its own. I got the plans nailed down and the cab is coming along. Note that I named it 'Harlow'. It has been changed significantly from the original U45.

[sepulchre]

Got the board together. Note that there are a lot of recycled parts on it; I think it's a nice mix of brands & materials. My aim is to keep the price down. Pretty sure it's going to come in under $160 out of pocket.

[Kagliostro]

Nice project I like it

Thanks for sharing

Very Beautiful Cab !

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I'm waiting for your impressions about 6f3p tubes

have you changed something in the realized layout respect to the drawn layout ?

Thanks

K

[sepulchre]

No, so far it's just like the drawn layout. Note that you cannot see the wiring on the back side of the board in that picture.

I will not know how it sounds until I get the transformers. Edcor takes awhile to produce their orders but are worth the wait, in my view.

And about the cab - thanks! I'm still working on the shade of stain it will get.

[Kagliostro]

Hi Sepulchre

just a question

was this Harlow (Gina)

[img:347:550]http://www.brillgallery109.com/exhibits ... _1-17a.jpg[/img]

to inspire you about this Harlow ?

[img:400:300]https://tubeamparchive.com/files/thumbs ... 10_182.jpg[/img]

K

[sepulchre]

Nope. This is Jean Harlow, the original 'platinum blonde'. I have always liked her spunky attitude and Great looks. But what made me think of her to name this amp is that the font I wanted to use is called 'Harlow'.

[statorvane]

That is a cool cab. Nice work burning in the characters.

Harlow, Colbert, Bow, Hayworth, deHavilland - none of the movie stars today have the... style or glamour of the older stars. They really were stars back then.

[sepulchre]

Thanks statorvane. I love all the great stars from that era - Bergman, Tierney, Loy, etc. but Jean Harlow never failed to grab my attention. She had a tragically short life, passing away at only 26 years old, which only serves to make her more immortal to me. (is that weird?)

[sepulchre]

A little PR . . .

[sepulchre]

Okay, so I finally got the sucker together. I have changed it in a pretty drastic way, eliminating the tremolo and using that triode as another gain stage. Plus I changed the power supply quite a bit. Ity actually has little resemblance to a U45b anymore except for using 6BM8s and a 6X4 rectifier.

I've got it working but it still has some problems, namely HUM. Here's the schematic. If anyone has good ideas for how to eliminate some hum please chime in.