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Post subject: 12AU7 Tube
Posted: Mon Oct 24, 2016 11:40 am
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My curiosity with tubes continues so please excuse another question.

What results could I expect if I were to put a 12AU7 in the PI position of my DRRI? Would it be a safe substitution to try?


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Post subject: Re: 12AU7 Tube
Posted: Mon Oct 24, 2016 1:30 pm
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It would be safe enough but I'm doubtful that you'd find the amp's tone very pleasing. The 12AU7 has the lowest gain of the most prolific dual-triode sub-miniatures commonly used in guitar amps.

Arjay

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Post subject: Re: 12AU7 Tube
Posted: Mon Oct 24, 2016 1:48 pm
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Retroverbial wrote:
It would be safe enough but I'm doubtful that you'd find the amp's tone very pleasing. The 12AU7 has the lowest gain of the most prolific dual-triode sub-miniatures commonly used in guitar amps.

Arjay


Thanks Arjay.

I don't think I'll be trying that then!


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Post subject: Re: 12AU7 Tube
Posted: Tue Oct 25, 2016 1:46 am
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I put a 12AY7 in V1 in a Carr Mercury amp for a customer who want less overdrive more " Fender" tone. The amp loss not very much output power but the clean are better and customer is very happy.
Before this mod he want to sell the amp, now he'll keep it.

This amp is a 8 watts amps !

I heard no difference in power output by ears with a 12AT7 ( 60% gain ) and 12AY7 (45 % gain ) but tone is better with a 12AY7.

More here; http://billmaudio.com/wp/?page_id=131


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Post subject: Re: 12AU7 Tube
Posted: Tue Oct 25, 2016 2:07 am
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I have read that unless the circuit is designed for it, you should not put a 12AT7 or 12AU7 in a tone generating position as these tubes are for current not voltage increase.

In tone positions 12AX7, 12AY7 and 5751 should be used.


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Post subject: Re: 12AU7 Tube
Posted: Wed Oct 26, 2016 12:45 am
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^ Yes ^

I have found no use for a 12AU7 in any amp, any position (save for the possibility of some oddball amp designed to use one). A 12AT7 is only good for reverb driver or PI.

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Post subject: Re: 12AU7 Tube
Posted: Wed Oct 26, 2016 2:43 am
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The 12AU7 was common in a number of vintage amp designs, most notably those of Sunn and Ampeg.

Arjay

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Post subject: Re: 12AU7 Tube
Posted: Wed Oct 26, 2016 4:03 am
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To tame the gain, my choice is always a 5751 in V1. But then, I stay away from extremely high gain amps.

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Post subject: Re: 12AU7 Tube
Posted: Wed Oct 26, 2016 6:52 am
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IM4Tone wrote:
To tame the gain, my choice is always a 5751 in V1. But then, I stay away from extremely high gain amps.


+1

It's generally easier to "heat up" a low-gain amp than it is to tame a high-gain monster -- any good OD pedal will get the job done. A 12AT7, 12AY7, or 5751 is a great choice for the V1 position of most Fender amps when smooth, articulate cleans are desired. An added benefit is, they usually have a better S/N ratio than a 12AX7/ECC83 so the amp runs a little quieter at idle.

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: 12AU7 Tube
Posted: Wed Oct 26, 2016 4:57 pm
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The 12AY7 is a nice tube to try in V1. Good, quiet, dependable sub-variety is the mil spec 6072 and 6072A. GE made the best.

http://www.ebay.com/sch/i.html?_odkw=ge ... A&_sacat=0


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