DIY Super Simple Preamp

[tusharganvir]

Thanks a lot for pointing it out Mishraji.... :thumbsup:

Will make the necessary changes as suggested.

Regards,
Tushar G

 

[tusharganvir]

I am back again with a small query.

My sources are legal MP3s purchased from Airtel Wynk @ 320kbps played thro' Raspberry pi B+ with Cirrus audio card.

Receiver :- CA SR 10

While listening I felt I have to increase the volume of pre-amp to 100% otherwise I have increase volume of my amp to high.

Can we increase gain?...if yes what are drawbacks of doing so.

Regards,
Tushar Ganvir

 

[gbalaram]

Hi Sachin,

I own a Norge 2060, can you help replacing the pre-amp section with SSP? I am a novice in electronics.

Regards,
Giri

 

[spirovious]

Hi,
I would like to know how can we adjust output gain?
If output of pre is matched with that of poweramp(say 1V) in,SSP can drive it very well.
How to know the actual output of SSP?
thanks.

 

[doors666]

Hey how does those Russian output caps sound? Better than older Mylar caps?

You should check and if your amp has an input cap, you can remove the output cap from the preamp. It is counter productive to have caps at both the preamp output and amp input. Caps in series reduce in value (like resistors in parallel). If your preamp has a 2.2uf cap and amp has the same, you get a 1.1uf cap between them. This drop in capacitance might be enough to kill your low bass.

 

[spirovious]

You should check and if your amp has an input cap, you can remove the output cap from the preamp. It is counter productive to have caps at both the preamp output and amp input. Caps in series reduce in value (like resistors in parallel). If your preamp has a 2.2uf cap and amp has the same, you get a 1.1uf cap between them. This drop in capacitance might be enough to kill your low bass.

Thanks.Yes Rotel power amps usually have input caps.
I need to check values.
I may add parallel caps in ssp on safer side.Ssp has some dc offset.

 

[jls001]

Hi,
I would like to know how can we adjust output gain?
If output of pre is matched with that of poweramp(say 1V) in,SSP can drive it very well.
How to know the actual output of SSP?
thanks.

Spiro,
Please explain what you mean by matching output of pre to that of power amp. I'm confused

 

[keith_correa]

I think he meant this - Amplifier Voltage Gain Explained Matching Amp to Preamp | Audioholics

 

[spirovious]

I think he meant this - Amplifier Voltage Gain Explained Matching Amp to Preamp | Audioholics

Yes.Same.I also think that unless we match output gain perfectly with that of poweramp,we may not get the best.

 

[gryph0n]

Yes I have few

Regards
Sachin

Sachin sir, as discussed, made payment for this Kit and a few others. PM'ed you the payment details.

 

[spirovious]

Hi,
I would like to know how can we adjust output gain?

Just found Om's formula to adjust gain in another forum-

With default schematic as above, it is -
Rf = R27, R29 = 10K
Rg = R28, R30 = 8.2K

output = input x A, gain

gain, A = (1 + Rf/Rg) where Rf = 10K and Rg = 8.2K
= 1 + 10/8.2
= 1 + 1.21
= 2.21

output = input x 2.21 times

with swap Rf = 8.2K and Rg = 10K

Gain A = 1 + (8.2/10)
= 1 + 0.82
= 1.82

output = input x 1.82 times

Now you can experiment lowering Rf to something 4.7K or increasing Rg to 15K or higher.

 

[akd06]

PM your address.I will send you a suitable Opamp.

Regards
Sachin

Kindly share your contact number, if possible. Thanks.