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Post subject: Re: the Fender BRIGHT switch
Posted: Tue May 08, 2012 12:12 pm
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bluesky636 wrote:
Rhust wrote:
correct me if I'm wrong, but also in addition to the switch, wasn't the #1 input on each channel considered the bright input?

I don't know if the bright switch affects both the #1 and #2 inputs. on each channel, or if affects both, but starts at a different starting point


No, the #1 input is the high gain input and #2 is low gain (6 dB less than #1).



are they both affected by the bright switch then? just from different points?


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Post subject: Re: the Fender BRIGHT switch
Posted: Tue May 08, 2012 1:42 pm
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Rhust wrote:
bluesky636 wrote:
Rhust wrote:
correct me if I'm wrong, but also in addition to the switch, wasn't the #1 input on each channel considered the bright input?

I don't know if the bright switch affects both the #1 and #2 inputs. on each channel, or if affects both, but starts at a different starting point


No, the #1 input is the high gain input and #2 is low gain (6 dB less than #1).



are they both affected by the bright switch then? just from different points?


Usually. Depends on the amp design. Pick an amp. Look at the schematic.

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Post subject: Re: the Fender BRIGHT switch
Posted: Wed May 09, 2012 3:48 pm
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bluesky636 wrote:
Toppscore wrote:
After some quick but not thorough checking around, it seems amps with presence do not have bright. Bright and Presence are not compatible???
Both statements are totally false. The 59 Bassman and 57 Twin (plus others of that period) had both "bright channels" and the Presence control. My 5F6A clone has both. My Blues Deluxe Reissue has both a bright switch and Presence control as does the Blues Deville Reissue. Although both brighten the amp's sound, they do it by totally different methods.
Bluesky = BOTH STATEMENTS * TOTALLY FALSE???
IS A BRIGHT SWITCH (subject of this thread, right?) THE SAME AS A BRIGHT CHANNEL INPUT? REALLY?
TOTALLY TRUE OR TOTALLY FALSE? Come on, answer one way or the other.

BELOW, are amps I PERSONALLY OWN that have either
a bright switch with no presence, or
a presence control with no bright switch.

1954 5D6 4x10 with NO BRIGHT SWITCH, but with a bright input, a presence control
1960 6G4 2x10 with NO bright switch, NO bright channel, a presence control
1962 6G4 2x10 with NO bright switch, NO bright channel, a presence control
1963 Tremolux with a bright switch, NO bright channel, NO presence control
1964 Bassman Blackface with NO bright switch, NO bright channel and a presence control
1964 Super Reverb 2 bright switches, NO bright channel, NO presence control

How are my amps TOTALLY FALSE????
Are my amps "one-of-a-kind" super-duper rare and worth millions$$$
NO, because they are TOTALLY COMMON!!!


Toppscore 8)

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Post subject: Re: the Fender BRIGHT switch
Posted: Wed May 09, 2012 5:44 pm
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Hey Topp, what model(circuit) is your '64 Bassman ? Art

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Post subject: Re: the Fender BRIGHT switch
Posted: Wed May 09, 2012 6:01 pm
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Hi, Aclempoppi!
With limited data base on my laptop,
I have the Serial Number = BP11922 * not the tube chart with me at this time.

It is the rare Blackface Black Tolex Bassman with the 7th presence control. Pretty cool.

You tell me, . . . . as an educated guess:
6G6-B (blonde)?
before the AA864 (blackface)?
or something else?


Recalling previous discussions, it's a Blonde Bassman within Black Wolf's clothing :shock:
Bought it in original near mint condition a few months ago.

Toppscore 8)

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Last edited by Toppscore on Wed May 09, 2012 6:22 pm, edited 1 time in total.

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Post subject: Re: the Fender BRIGHT switch
Posted: Wed May 09, 2012 6:11 pm
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Wow! That is nice. Yeah, my guess would be the 6G6-B. Never had the pleasure of playing one of those. Keep Pickin' , Art

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Post subject: Re: the Fender BRIGHT switch
Posted: Wed May 09, 2012 9:51 pm
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Toppscore wrote:
bluesky636 wrote:
Toppscore wrote:
After some quick but not thorough checking around, it seems amps with presence do not have bright. Bright and Presence are not compatible???
Both statements are totally false. The 59 Bassman and 57 Twin (plus others of that period) had both "bright channels" and the Presence control. My 5F6A clone has both. My Blues Deluxe Reissue has both a bright switch and Presence control as does the Blues Deville Reissue. Although both brighten the amp's sound, they do it by totally different methods.
Bluesky = BOTH STATEMENTS * TOTALLY FALSE???
IS A BRIGHT SWITCH (subject of this thread, right?) THE SAME AS A BRIGHT CHANNEL INPUT? REALLY?
TOTALLY TRUE OR TOTALLY FALSE? Come on, answer one way or the other.

BELOW, are amps I PERSONALLY OWN that have either
a bright switch with no presence, or
a presence control with no bright switch.

1954 5D6 4x10 with NO BRIGHT SWITCH, but with a bright input, a presence control
1960 6G4 2x10 with NO bright switch, NO bright channel, a presence control
1962 6G4 2x10 with NO bright switch, NO bright channel, a presence control
1963 Tremolux with a bright switch, NO bright channel, NO presence control
1964 Bassman Blackface with NO bright switch, NO bright channel and a presence control
1964 Super Reverb 2 bright switches, NO bright channel, NO presence control

How are my amps TOTALLY FALSE????
Are my amps "one-of-a-kind" super-duper rare and worth millions$$$
NO, because they are TOTALLY COMMON!!!


Toppscore 8)


Wow. Where do I start to explain something so simple to someone so clueless? This could take awhile, so bear with me.

1. First of all, do you understand what a "bright channel", "bright switch", or "presence control" even is? Probably not, so let me explain.

A. Let's start with the most complicated circuit first, the presence control. The presence control is a potentiometer and capacitor circuit that operates within the negative feedback loop between the output transformer secondary and the phase inverter input. The feedback loop works to reduce the open loop gain of the amp's output stage, thereby reducing distortion and also making the amp more stable and less prone to oscillation and other nasty effects. The presence circuit works by modifying the feedback circuit so that the gain of the feedback loop is frequency dependent. As the presence control is advanced, the high frequency gain of the amp is increased in relation to the low frequency gain, thereby providing a brighter sound, and to some extent, sightly more distortion in the high frequencies. As the presence control is reduced, high frequency gain is reduced and the low frequency response is tightened up.

B. The bright channel used in many early Fender amp designs, as well as Marshall amps, consists simply of a small capacitor placed across the input and output lugs of the volume control. At maximum volume, the capacitor is shorted out and has no effect. As the volume is reduced, high frequencies are shunted around the volume control, resulting in a brighter sound.

C. The bright switch used on many amps can take the form of one of two common designs. In the first, a small cap is placed across the input and output lugs of the volume control, just like in the bright channel. In addition, a switch is placed in series with the cap allowing you to switch the cap in and out of the circuit. When switched in, the operation of the volume control is identical to that of the bright channel. The other design places a parallel RC network in series with the signal line in one of the preamp stages. When switched in, the frequency response is altered such that low frequencies are rolled off in relation to the high frequencies, again making for a brighter sound.

d. I suggest that you review a few schematic diagrams of amps using these circuits to help you understand what I am talking about. Incidently, one can also add "bright switches" to different values of coupling capacitors or cathode bypass capacitors to change the frequency response of an amp. All of the circuits discussed here are independent of any type of tone stack the amp may use.

e. You may want to do a little reading on the history and evolution of the bright channel, presence control, and bright switch in Fender amps. Tom Wheeler's book, "The Soul of Tone: 60 Years of Fender Amps" would be a good place to start.

2. Now, regarding your statement that "it seems amps with presence do not have bright", I already gave some examples that prove that statement to be false. I'll repeat those in case you missed them and add a few more:

a. 5E6, 5E6A, 5F6, 5F6A Bassman, 59 Bassman Reissue - Bright channel and presence control
b. 5D8, 5E8, 5E8A, 5F8, 5F8A Twin, 57 Twin Reissue - Bright channel and presence control
c. 5G13 Vibrosonic - Unswitched bright cap in vibrato channel and presence control
d. 5E7 Bandmaster - Bright channel and presence control
e. 5E5A Pro Amp - Bright channel and presence control
f. Pro Tube Reverb - Bright switch and presence control
g. 6G5 Pro Amp - Unswitched bright cap in vibrato channel and presence control
h. Hot Rod Deluxe/Deville original and reissue - Bright switch and presence control
i. Blues Deluxe/Deville original and Reissue - Bright switch and presence control

There may be others that I missed. Sorry.

3. And your last statement, "Bright and Presence are not compatible???" is clearly false based on the amps listed above.

You're welcome. Apology accepted.

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Post subject: Re: the Fender BRIGHT switch
Posted: Wed May 09, 2012 10:43 pm
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Bill, do you recall who Don Quixote was?

:wink:

Arjay

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Post subject: Re: the Fender BRIGHT switch
Posted: Thu May 10, 2012 12:55 am
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[b]1) After some quick but not thorough checking around, it seems amps with presence do not have bright.
2) Bright and Presence are not compatible???

From Bluesky: "Both statements are totally false."!!

==========================
Geeeezzzzzzzzzzz Mr Bluesky!!!

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Last edited by Toppscore on Tue May 15, 2012 6:10 am, edited 1 time in total.

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Post subject: Re: the Fender BRIGHT switch
Posted: Thu May 10, 2012 2:01 am
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Also, Bluesky.
Thank you for sharing the above information about
bright switches, bright channels and presence controls.

Learned much, much appreciated. Toppscore 8)

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Post subject: Re: the Fender BRIGHT switch
Posted: Thu May 10, 2012 5:20 am
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Retroverbial wrote:
Bill, do you recall who Don Quixote was?

:wink:

Arjay


Yeah. I know. I just couldn't resist.

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Post subject: Re: the Fender BRIGHT switch
Posted: Thu May 10, 2012 5:32 am
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OK, but what was the lesson, that the story was teaching us? Art

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Post subject: Re: the Fender BRIGHT switch
Posted: Thu May 10, 2012 5:47 am
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aclempoppi wrote:
OK, but what was the lesson, that the story was teaching us? Art


Perhaps that people should clearly understand what their words mean and how they will be interpreted by those who read them?

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Post subject: Re: the Fender BRIGHT switch
Posted: Thu May 10, 2012 6:06 am
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My bad, if it ain't about resistors and caps, Bill, I really don't have any business asking that kind of question! Where the heck is Shimmy? Art

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Post subject: Re: the Fender BRIGHT switch
Posted: Thu May 10, 2012 8:12 am
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aclempoppi wrote:
My bad, if it ain't about resistors and caps, Bill, I really don't have any business asking that kind of question! Where the heck is Shimmy? Art


Ah, but in reality it was simply about resistors and caps and understanding how they are put together to perform the functions we want in our amps. :D

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