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Post subject: Re: The Brown Box for vintage amps
Posted: Mon Jun 01, 2015 9:27 am
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Do you own any vintage amps?

It's difficult to understand how these amps perform unless you have some perspective.

As for "snake oil", yeah......there's a lot of that being pushed, mostly by hustlers who have little grasp of electronics or the practical applications of it. "Monster" speaker cables, vacuum tubes with gold-plated pins, and three-hundred dollar power cables fit that paradigm. However, the "Brown Box" does not fall into the same category since its performance is definitively quantifiable by scientific measurements.

Arjay

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Post subject: Re: The Brown Box for vintage amps
Posted: Mon Jun 01, 2015 11:23 am
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Retroverbial wrote:
Do you own any vintage amps?

No. And I have 230V anyways.

Quote:
However, the "Brown Box" does not fall into the same category since its performance is definitively quantifiable by scientific measurements.

Fair enough.


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Post subject: Re: The Brown Box for vintage amps
Posted: Mon Jun 01, 2015 12:20 pm
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I just receive a Pro Reverb Amp , my customer bought NOS Tung Sol 6L6WGB

Few tests ;

Normal 122.8 AC wall outlet ; At 70 % bias , plate voltage ; 470 volt DC .
Very high for specs which are 400 V plate Maximum Absolute Values
Tone is ( little ) agressive at 122 VAC

At 117 volts ; bias 70% , plate volt 447 volts DC ( sound better )

Fender schematic show 440 VDC plate

I put 3 zeners ; Plate voltage is now 437 VDC


Last edited by stratele52 on Mon Jun 01, 2015 2:30 pm, edited 1 time in total.

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Post subject: Re: The Brown Box for vintage amps
Posted: Mon Jun 01, 2015 12:50 pm
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stratele52 wrote:
Fender schematic show 440 VDC plate

I put 3 zeners ; Plate voltage is now 437 VDC


That's as close to perfect as perfect can be.

Rawk on!

8)

Arjay

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Post subject: Re: The Brown Box for vintage amps
Posted: Mon Jun 01, 2015 2:33 pm
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I'm very surprise how higher wall outlet change tone of these old amp .

And how the right voltage make these amp munch better sounding .


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Post subject: Re: The Brown Box for vintage amps
Posted: Mon Jun 01, 2015 3:49 pm
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stratele52 wrote:
I'm very surprise how higher wall outlet change tone of these old amp .

And how the right voltage make these amp munch better sounding .



+1

I performed a similar comparison some time ago using my Variac to regulate the input voltage. The sonic improvement, while not dramatic, was significant enough that I'm seriously considering a Brown Box purchase.

Arjay

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Post subject: Re: The Brown Box for vintage amps
Posted: Mon Jun 01, 2015 4:27 pm
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Retroverbial wrote:
stratele52 wrote:
I'm very surprise how higher wall outlet change tone of these old amp .

And how the right voltage make these amp munch better sounding .



+1

I performed a similar comparison some time ago using my Variac to regulate the input voltage. The sonic improvement, while not dramatic, was significant enough that I'm seriously considering a Brown Box purchase.

Arjay


Yes not dramatic maybe on most amps ( like the Pro Reverb Amp ) but for the Deluxe reverb , it is day and night .


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Post subject: Re: The Brown Box for vintage amps
Posted: Mon Jun 01, 2015 6:23 pm
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Ok, I'm sold. At least I'll try it. The zener mod is what I 'll try. The Box is out of my range. I've got a BF Pro coming up and the owner has good ears. We'll see...
But to backtrack to another time, I see Leo trying out different B+ setups to hear what sounded best. I guess he did the hard work chasing tone for us. Now I just need to implement his 50 year old specs...again


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Post subject: Re: The Brown Box for vintage amps
Posted: Mon Jun 01, 2015 6:39 pm
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I have a question regarding the Zener diode method. I have come across many a wall outlet with voltages way below the 120v range, some as low as 108v. Now being that the Zener diode method is permanent, how is the tone being affected by a severe voltage drop? Would it be possible to install said diodes via a bypass switch instead, and without a voltage meter how does anyone know what voltage they're plugging in to? I mean, besides knowing what voltages I'm getting at home, without a meter I don't know what the voltages are going to be from one event to the next.

Just a thought.

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Post subject: Re: The Brown Box for vintage amps
Posted: Tue Jun 02, 2015 1:53 am
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TimsAudio wrote:
.
But to backtrack to another time, I see Leo trying out different B+ setups to hear what sounded best. I guess he did the hard work chasing tone for us. Now I just need to implement his 50 year old specs...again


My quest for the right voltage is because my customer what their vintage amp close as possible to original specs . Wall voltage is one because it change the tone .
You may like more the sound with higher voltage like many mods we can do to a amp . It is a matter of taste .


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Post subject: Re: The Brown Box for vintage amps
Posted: Tue Jun 02, 2015 2:01 am
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socal323 wrote:
I have a question regarding the Zener diode method. I have come across many a wall outlet with voltages way below the 120v range, some as low as 108v. Now being that the Zener diode method is permanent, how is the tone being affected by a severe voltage drop? Would it be possible to install said diodes via a bypass switch instead, and without a voltage meter how does anyone know what voltage they're plugging in to? I mean, besides knowing what voltages I'm getting at home, without a meter I don't know what the voltages are going to be from one event to the next.

Just a thought.


Zener diodes is a inexpensive ( few $ ) ,easy to do and reversing "mod " to original ; Just a wire to solder to ground and remove the terminal strip ; no hole in chassis. nothing . Just adjust bias .

Yes you can put a switch but where ?
How to know the voltage , wall or zener/power supply ? Meter only :(


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Post subject: Re: The Brown Box for vintage amps
Posted: Tue Jun 02, 2015 8:39 am
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Low AC voltage won't hurt your amp. Obviously, it won't be performing to optimum.
If you are measuring 108 VAC at a location where you play regularly, measure the voltage throughout the building. If only a few outlets are low, it's house wiring at fault and should be checked to prevent fire.
If it's low throughout the building, call your power company. There may be something overloaded in the power lines. It's their responsibility to maintain voltage to spec.


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