How much gain will a DIY G9 produce?

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deepmojoman

Member
Joined
Jan 7, 2017
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9
On the Gyraf Audio G9 DIY page, there is a quote: "The output driver is a 18dB gain SRPP stage . . . ".

Is that the total amount of gain I can expect this preamp to put out? That seems really low.
 
deepmojoman said:
On the Gyraf Audio G9 DIY page, there is a quote: "The output driver is a 18dB gain SRPP stage . . . ".

Is that the total amount of gain I can expect this preamp to put out? That seems really low.

No, that is just the gain of the output stage. There is a gain stage before that and before that stage  is a transformer.

Cheers

ian
 
ruffrecords said:
No, that is just the gain of the output stage. There is a gain stage before that and before that stage  is a transformer.

Cheers

ian

Cool. So, just to be clear: you're saying my signal will gain up some from the step up of the input tx, and then V1 is producing gain as well (as, of course, it would. The way the quote was stated on the G9 site could've been clearer.)

Do you think the total gain of the preamp would approach 60-70db?
 
deepmojoman said:
Cool. So, just to be clear: you're saying my signal will gain up some from the step up of the input tx, and then V1 is producing gain as well (as, of course, it would. The way the quote was stated on the G9 site could've been clearer.)

Do you think the total gain of the preamp would approach 60-70db?

It should be in that region.

Cheers

Ian
 
deepmojoman said:
Do you think the total gain of the preamp would approach 60-70db?

I remember 55-65dB depending on Transformers and Tubes.
OEP Irons will give you less gain but more color to the sound,Lundahls a bit more gain less color.

But however you build the unit... you will love it on accoustik guitars,vocals and even bass guitars (DI)

Read the Help-Thread and definitely do the modifications :)

Greets
 
It should be around 55db.  Might seem close to "60-70" but in real the difference is huge.  Still 55 should be enough for most sources. If you want more, you can squeeze it in several ways, but it is a bit beyond beginner level.
 
If you look at the schematic you have:

Input transformer 6.45:1 ratio =  +16dB
Amplifier max gain is 47  times =  +33dB
SRPP stage gain +18dB
Output transformer 2:1 = -6dB

Max gain is 16 + 33 +18 - 6 = 61dB

Cheers

Ian
 
There is voltage halving at the potentiometer, it makes a voltage divider with R26.  At least I noticed this in mine after I removed the pot and replaced it with a simple 47K shunt.  Seemed like the best way to simulate a full open pot.    The shunt can be made 1M to let the whole signal pass but then the low gain switch area will not work properly.
 

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