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Post subject: Bucking Transformer
Posted: Fri Dec 08, 2017 3:05 pm
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I put this together the other day. Works pretty good now my amps should be a little more happy, could be my imagination but I think my amp sounds better than without it, might have a smoother tube break up earlier, could be wishful thinking on my part.
Question if anyone has an answer....... my VC is 0.5 Amps, my SR is 1.5 Amps, being this is a 4 Amp transformer with a 4 amp slow blow fuse can I run both at the same time or do I need to build another one
Top receptacle is Wall voltage
Image
Bottom Receptacle is Bucked - 6 VAC and -12VAC with the SPDT switch
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Image
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mud


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Post subject: Re: Bucking Transformer
Posted: Fri Dec 08, 2017 4:59 pm
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Nice build Mud,
you should be able to run both amps w/ it as long as you want them to both run at the same voltage drop.
And I'm sure it sounds better and the components should be happier!


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Post subject: Re: Bucking Transformer
Posted: Fri Dec 08, 2017 6:17 pm
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Nice build! Did you use the Hammond 166N12B filament heater transformer? I have all the parts, but just haven't gotten around to building it, yet.

Good, you got one working!


:)


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Post subject: Re: Bucking Transformer
Posted: Sat Dec 09, 2017 10:44 am
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sfceric64 wrote:
Nice build Mud,
you should be able to run both amps w/ it as long as you want them to both run at the same voltage drop.
And I'm sure it sounds better and the components should be happier!


Thanks. I do want the voltage drop on both, as sometimes when a friend stops by I will put a 2 x 12 cabinet @ 4 Ohm on the 67 VC and use my 69 SR at the same time, and running a GE copper plate 5AR4 and GE 6L6's I want to give them as much life as I can get. I figure the voltage drop is a little easier on them.
mud


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Post subject: Re: Bucking Transformer
Posted: Sat Dec 09, 2017 10:51 am
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BMW2002Ti wrote:
Nice build! Did you use the Hammond 166N12B filament heater transformer? I have all the parts, but just haven't gotten around to building it, yet.

Good, you got one working!


:)

Yes the Hammond 166N12B filament heater transformer is exactly what I used, my biggest issue I had in the build was drilling out for the light, it needed a 5/8 drill bit and I didn't have one, it took a few days but I managed to get it drilled out from another department at work
mud


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Post subject: Re: Bucking Transformer
Posted: Thu Dec 14, 2017 2:12 am
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Location: Province de Québec, Canada
I can't see pictures with Safari :(

I switch to Google Chrome , I see them now :D

Where did this post started ? I don't understand why the use of this :(


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Post subject: Re: Bucking Transformer
Posted: Thu Dec 14, 2017 6:28 am
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Location: Denver, CO, USA
Standard US line voltage is higher now than in the '50s and '60s. Bucking transformers are a common way to lower the voltage for those who are concerned about running modern voltage into vintage gear. (Or vintage-spec clones/repros.) The idea has been popular with collectors of vintage tube radios and users of vintage tube hi-fi gear for a long time.

Compared to an autotransformer (Variac), they're smaller, lighter, less expensive, more efficient (generate less heat), and you don't have to worry about the knob getting turned to the wrong position.


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Post subject: Re: Bucking Transformer
Posted: Thu Dec 14, 2017 6:46 am
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Location: Province de Québec, Canada
Thank for answer, I understant now.

I use zener diodes on my vintage ( 110 volts line ) amps to downsize 125 volts wall outlet

Here on Vibro Champ;

A easy mod inside the amp and easy to return original.
Image[url=https://flic.kr/p/22uQKR2]DSC03671


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Post subject: Re: Bucking Transformer
Posted: Thu Dec 21, 2017 9:58 am
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stratele52 wrote:
Thank for answer, I understant now.

I use zener diodes on my vintage ( 110 volts line ) amps to downsize 125 volts wall outlet

Here on Vibro Champ;

A easy mod inside the amp and easy to return original.
Image[url=https://flic.kr/p/22uQKR2]DSC03671

stratele52 that's pretty cool. For my needs, having the choice of -6VAC or 12VAC works better in the USA as I have 120 to 122 VAC in my house, and my friend 10 miles from me has 125 to 127 in his house. Having 121VAC minus 6 VAC = 115 and 126VAC minus 12VAC = 114VAC
mud


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Post subject: Re: Bucking Transformer
Posted: Thu Dec 21, 2017 11:07 am
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Mud ,
Bucking transformer is a great idea I never heard about, thank's


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Post subject: Re: Bucking Transformer
Posted: Fri Dec 22, 2017 9:34 pm
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Thanks Mud.
I thought this looked easy enough to build...so I gave it a try. I will be using it with my 1965 Bandmaster.

I used the original author's simplified version, but added an ON-OFF switch.
I could not find a 12-Volt Center-tap transformer with 4-amp rating at my local supply shop...so I bought a 2-amp transformer and a 2-amp fuse. Hopefully that current rating is enough.

All-parts in Canadian Loonies:
Circuit-Test 640-122 Trans 12-VAC CT/2-Amp $19.95
Fuse Block 1-1/4 x 1/4 inch $1.50
2-Amp Fuse slow blow $1.50
Switch $1.49
Duplex Outlet $1.95
PVC box gang thing $4.79
Cover plate $2.29
Power Cord...salvage piece $0.00

Wall Voltage: 122.2v
Image
7% Drop (114.6v)
Image
12% Drop (107.3v)
Image
OFF-Position (0V)
Image

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Post subject: Re: Bucking Transformer
Posted: Tue Jan 02, 2018 9:26 am
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BasementBob wrote:
Thanks Mud.
I thought this looked easy enough to build...so I gave it a try. I will be using it with my 1965 Bandmaster.

I used the original author's simplified version, but added an ON-OFF switch.
I could not find a 12-Volt Center-tap transformer with 4-amp rating at my local supply shop...so I bought a 2-amp transformer and a 2-amp fuse. Hopefully that current rating is enough.

All-parts in Canadian Loonies:
Circuit-Test 640-122 Trans 12-VAC CT/2-Amp $19.95
Fuse Block 1-1/4 x 1/4 inch $1.50
2-Amp Fuse slow blow $1.50
Switch $1.49
Duplex Outlet $1.95
PVC box gang thing $4.79
Cover plate $2.29
Power Cord...salvage piece $0.00

Wall Voltage: 122.2v
Image
7% Drop (114.6v)
Image
12% Drop (107.3v)
Image
OFF-Position (0V)
Image

Looks good 2 amp should be OK I'm not sure how many amps your band master pulls but my super reverb pulls 1.5 amp
mud


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Post subject: Re: Bucking Transformer
Posted: Tue Jan 02, 2018 9:35 am
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Most of my Fender amps need 2 amps. We know it is at maximum volume.

My SF Vibrolux reverb, my Bandmaster and my Tremolux need 2 amps


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Post subject: Re: Bucking Transformer
Posted: Wed Jan 03, 2018 7:51 am
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The 2-amp transformer seems to be working fine. My Bandmaster is labelled 1.5AMP @117 volt....therefore I assume it will be OK. I don't play at high volume or for very long at any one time...so long-term I can't say how it will hold up, but for now all is good. Thanks again.

Image

Now...next task....deal those old Capacitors. :oops:

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