Pre '60 style TV front AC4 build

Vox and Hiwatt Discussion

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sluckey
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Re: Tiny/bright 8" speaker?

Post by sluckey »

ChopSauce wrote: Thu Sep 10, 2020 10:02 am
1. find a 8" 8 Ohms Vox Bulldog speaker, which seems unlikely in my country, or

And, oh yes: it's all in the spirit of a cheap small pratice amp... :wink:
I vote for the Vox Bulldog. I bought three Pathfinders on eBay just to use the cab and that speaker. It has a very chimey (bright) sound when used with my Vox AC-15 lite. Could even be used as a gigging amp if mic'ed. If you can find one grab it.

http://sluckeyamps.com/dual_lite/dual_lite.htm
ChopSauce
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Re: Tiny/bright 8" speaker?

Post by ChopSauce »

Wish me: "good luck"... :?

It seems that I wasn't wrong, though... :wink:

This dual lite amp is a pretty impressive sleeper, by the way... 8)
ChopSauce
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Location: So Paris, France

Re: Pre '60 style TV front AC4 build

Post by ChopSauce »

This one came by me this morning... 8)
(from Thomann.de)
DSC08414.JPG
Its box reads: SLM Electronics, St Louis, Mo.

Poor carbon budget: from UK to France via USA, then Germany... :wink:

Its installation into the cab will require some significant rework, now. "A propos" - if anyone has ever tried to re-install a Vox grillcloth:

- if I take it appart and dip it again into water, will it shrink again when drying or am I supposed to use a new piece of grillcloth?
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ChopSauce
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Location: So Paris, France

I've got a (2") bigger problem now

Post by ChopSauce »

sluckey wrote: Tue Mar 03, 2020 6:15 pm Just a little sidebar... Back in the '60s hum was not a problem with the AC-4, Champ, or other similar small SE practice amps with minimal filtering. Oh, the hum was there alright, but that cheap 8" speaker could not reproduce it very well, so you just couldn't hear it. Then people started connecting a better quality 12" speaker and all of a sudden there was hummmmm.
Guess what: yet the speaker is sounding awesome, it is (very) very loud... :?

So I'm thinking about upgrading its filtering as per
sluckey wrote: Tue Mar 03, 2020 2:59 pm Refer to the service manual you posted.

1. Break the connection between the junction of the rectifier diodes and point B+.
2. Install a 250Ω/10W resistor between the junction of the diodes an point B+.
3. Connect a 100µF cap between the junction of the diodes and ground.

For even better hum filtering, use a choke rather than a 250Ω resistor.
&
xtian wrote: Tue Mar 03, 2020 4:56 pmYou don't need more than 50mA current...
In detail, the plan would be: inserting a 47uF reservoir cap, which is the most the EZ81 is supposed to handle, but I'm not sure about the DSR/resistance value of the choke. I guess the most important the resistance, the better filtering so:

- an Hammond Choke 154H (300 Ohms) should even better suit than Hammond 194A Choke Fender 125C3A / 022707 (167 Ohms) - both being 4H and good for 50 mA,

but the highest(*) the voltage drop, too - right?
___

(*) & how much the absolute difference in voltage drop... :?:
ChopSauce
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Location: So Paris, France

Post by ChopSauce »

EDIT: I didn't even think I should put the choke instead of the first (1k, 5W) resistor... :roll:

I guess a (Hammond 157H) 20 mA, 408R, 10H capable choke should suit, right... :?:
ChopSauce
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Joined: Wed Mar 15, 2017 12:08 pm
Location: So Paris, France

Re: Pre '60 style TV front AC4 build

Post by ChopSauce »

Finally ...
60sVoxAC4-front.jpg
60sVoxAC4-panel.jpg
... the revised layout used for this https://ampgarage.com/forum/viewtopic.php?f=10&t=34363 second "clone" solved my background noise concerns.

So I won't bother with chokes and I'll keep it as is, for reference, until - maybe - I find some time to convert it to my revised layout.

As is, you can hear it through a "no name" neutral/dull 10" speaker from a (most likely) modeling Fender amp:
(credits to my mate Franck)
ac4-tv-defil_jazz.mp3
ac4-tv-epiphone_sheraton.mp3
ac4-tv-telecaster.mp3
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ChopSauce
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Re: Pre '60 style TV front AC4 build

Post by ChopSauce »

sluckey wrote: Thu Sep 10, 2020 10:59 am
ChopSauce wrote: Thu Sep 10, 2020 10:02 am
1. find a 8" 8 Ohms Vox Bulldog speaker, which seems unlikely in my country, or

And, oh yes: it's all in the spirit of a cheap small pratice amp... :wink:
I vote for the Vox Bulldog. I bought three Pathfinders on eBay just to use the cab and that speaker. It has a very chimey (bright) sound when used with my Vox AC-15 lite. Could even be used as a gigging amp if mic'ed. If you can find one grab it.

http://sluckeyamps.com/dual_lite/dual_lite.htm
Yet another post for the sake of completion: I finally put a small 8" loudpseaker from a Marshall-alike transistor combo into it.

This nicely completed the job to make it sound like the small cheap practice amp with british tone, that it is supposed to be.
(that is a touch more "clear" than the recording)
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