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Post subject: Gain switch for Deluxes & Jr
Posted: Wed Apr 19, 2017 8:03 pm
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This is a little thing I cooked up for studio or club use.
It cuts gain in the main stage. This way, the preamp crunch still works the same. It reduces gain more than 12AT7 tube swaps
It works for HRDX, BDX, and Blues Jr.
Its just a switch that adds another feedback resistor to lower gain.
In the Blues Jr, I use a 22K. In the HRDX I use a 10K The choice of resistor is up to U. Fenders use as low as 820 ohms. I go for a 50% drop in volume, but almost any amount is available.
To dial it in, I use a 100K pot across the feedback resistor. to tune in in the amount of attenuation I want. Then I install the fixed value. It’s a stable, safe mod that flattens dynamics and makes the Presence control work more. Or U can switch in full dynamics.

I use a shielded wire to take the heat around the tubes. The center conductor goes to the PI side of the existing resistor and the new resistor connects to the OT side. Hum is usually not a problem though. It is shown at the bottom of the photo. with the red arrow.
The wires slip between the chassis and the tube sockets. No new holes are drilled.
The little heat shield/ mounting plate is from thin aluminum. A 9-volt battery case would probably work as well. I cut this one with scissors and a nibbler. One screw from the chassis mounts it. The metal is just wide enough to slip under the flanges of the tube sockets. Still, it’s a little flimsy and I secured it with JB weld. Now it’s rock ready.

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Post subject: Re: Gain switch for Deluxes & Jr
Posted: Thu Apr 20, 2017 1:01 am
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TimAudio, you will always blow me by your knowledge and your imagination.

It's great to read from you


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Post subject: Re: Gain switch for Deluxes & Jr
Posted: Fri Apr 21, 2017 2:41 pm
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stratele52 wrote:
TimAudio, you will always blow me by your knowledge and your imagination.

It's great to read from you


Stratele,

Sometimes you might want to consider translating what your writing before posting it. This one here gave me a good laugh.
:lol:

What I think you meant was "blow my mind". :wink:

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Post subject: Re: Gain switch for Deluxes & Jr
Posted: Fri Apr 21, 2017 3:59 pm
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socal323 wrote:
stratele52 wrote:
TimAudio, you will always blow me by your knowledge and your imagination.

It's great to read from you


Stratele,

Sometimes you might want to consider translating what your writing before posting it. This one here gave me a good laugh.
:lol:

What I think you meant was "blow my mind". :wink:


I do my best for translating with google :oops:


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Post subject: Re: Gain switch for Deluxes & Jr
Posted: Sat Apr 22, 2017 8:14 am
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stratele52 wrote:
I do my best for translating with google :oops:

You do better here than I do in Quebec, where I have to look for "Ici on parle anglais" signs. Otherwise I risk insulting someone's grandmother and dog by accident, trying my school French.


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Post subject: Re: Gain switch for Deluxes & Jr
Posted: Sat Apr 22, 2017 8:38 am
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It translated well enough. Thanks Stratle52.


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Post subject: Re: Gain switch for Deluxes & Jr
Posted: Sat Apr 22, 2017 9:43 am
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Interesting control. By flattening dynamics you mean the switch effects gain and freq response at the same time? How about the THD-distortion. A Jazz/Blues Amp switch, more Studio/Club switch? I think my Blues Deluxe has a Presence control. I haven't used that amp for a while, I forgot what it sounds like. But this is more to do with gain? Anyway, Thanks TimsAudio.


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Post subject: Re: Gain switch for Deluxes & Jr
Posted: Sat Apr 22, 2017 7:00 pm
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The mod doesn't change the tone, just the punchyness to soften the peaks and increase sustain.
Guitars make percussive notes. The ratio of the peak to decay is designed into the amp. Its the total multiplication of the signal by the individual gain stages. Changing the volume control doesn't change that ratio in a good tube amp. Changing the multiplication factor is the key.
Lower gain preamp tubes are commonly used to accomplish this. swapping a 12AX7 for a 12AT7 and 12AU7 will lower it some, but not in the right place and not enough to make a real difference.
This mod works in the main stage and has more cut available. The preamp stages are still hi gain, so crunch is still readily available.

Feedback is commonly used to flatten the tone peaks and reduce distortion in hifi amps. While distortion specs are kinda meaningless in a guitar amp, too much feedback reduces transient response.

The Presence control is a tone control for the main power stage. It works in the NFB loop, so more signal through the loop=more presence control function.


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Post subject: Re: Gain switch for Deluxes & Jr
Posted: Sat Apr 22, 2017 11:20 pm
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TimsAudio wrote:
The Presence control is a tone control for the main power stage. It works in the NFB loop, so more signal through the loop=more presence control function.


That's the best descriptive for the enigmatic presence control I've ever read.

+1!

Arjay

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Post subject: Re: Gain switch for Deluxes & Jr
Posted: Sun Apr 23, 2017 1:54 am
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arth1 wrote:
stratele52 wrote:
I do my best for translating with google :oops:

You do better here than I do in Quebec, where I have to look for "Ici on parle anglais" signs. Otherwise I risk insulting someone's grandmother and dog by accident, trying my school French.


English /american speaking people are alway welcome in Quebec province. No need to look for "we speak english her" signs. Lots of people can speak english enough to help you.
I'm sorry TimAudio to pollute your captivating subject.


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Post subject: Re: Gain switch for Deluxes & Jr
Posted: Sun Apr 23, 2017 8:25 am
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I've always felt welcome when travelling in Canada. I HH the trans-Canada Hwy as a weanling in the 70s. When I crossed in at Toronto, the customs agents were so sure I was going to Banff because I had a backpack.
I was going to cross back in at Thunder Bay, but they were so descriptive about the parks that I asked them if I had enough money to travel out there. It was only then they realized that I really never had heard of the place. They were so nice.
It was a weeklong crossing and I met a lot of nice people. Banff and Jasper lived up to the hype and I had a great time. I went back twice.
It almost felt like America except for my encounters with law enforcement, wich is a common occurance for a cross country hitch hiker. The highways are their turf.
In america, it was," Can I search your pack for weapons?" That's the only reason for a search without probable cause. In Canada, it was. "Empty your bag on the ground" No search warrant needed.
Then the police declaring,"This is a public place" and everybody walks away. Apparently no right to assemble.
The further North I HH, the nicer the people got and fewer weird rides. The Canadians were the nicest. But I would rather live with a few weirdos than lose protected American values. If you've never been, you should go visit.


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Post subject: Re: Gain switch for Deluxes & Jr
Posted: Sun Apr 23, 2017 10:34 am
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"Weanling", LMAO!

IOW, a distant relative of a whelp or a whippersnapper.

:mrgreen:

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Gain switch for Deluxes & Jr
Posted: Sun Apr 23, 2017 1:32 pm
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My Mom is to blame for my travellin bone.
As a whelp, she put me alone on the mail train from Chatsworth to my cousins at Vallejo at 7. When I was a whippersnapper at 12 I wore my first traveling suit and tie. She bought me a wristwatch at the LA station and a black man shined my shoes. Then I got on the City of St Louis for 3 days to Missouri and back. Great summer on a Missouri farm. So glad Amtrack modernized an outdated passenger system. There was no reservation system. You paid a porter to find you a seat. If someone else pays him more, you may find your seat bumped any time you pull into another station..
I think Mom wanted me to get a perspective of America the same way she did. After nursing school, she rode the rails tending wounded soldiers for a year until she was old enough to ship out for the Battle of the Bulge. That was growin up fast with no time to enjoy the travel. She was livin it through me and I still relish road trips.


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