How can I increase pickup output voltage?

Brastep

I recently built an el-cheapo solid-state amp from a kit as a fun project and to put a spare old 8" speaker to some use. The amp is rated at 20W RMS, which I thought at the time of purchase would be sufficient. It works, but the volume is very weak, nowhere near 20W. Having assembled the kit and read the instructions (yes, in that order!), I see that the 20W output rating assumes that the input voltage to the amp is around 2V. I believe that a guitar pickup will deliver in the range of 100mV to 1000mV. Does anyone know of a simple curcuit I can build that will boost the pickup-to-amp voltage without altering the signal characteristics too much?

Psean

Is the amp only a power amp or does it have a pre-amp stage as well?

AlanRatcliffe

+1 Psean. The highest output humbucking pickups will only output about 500mV, so you need a preamp for your power amp.

Also, if you want it to sound like a guitar amp, you'll need it to mimic/model the tonal response of a real, valve-driven amp and speaker (both of which are big parts of the sound of an electric guitar). Simplest way to do this is to lay your hands on a POD, SansAmp or other amp modelling pedal, and use that as your preamp.

Otherwise there are plenty of circuit diagrams available on the internet - whole sites dedicated to guitar effects and amplifiers. Google is your friend (in this case ?).

Psean

Alan Ratcliffe wrote: +1 Psean. The highest output humbucking pickups will only output about 500mV, so you need a preamp for your power amp.

Also, if you want it to sound like a guitar amp, you'll need it to mimic/model the tonal response of a real, valve-driven amp and speaker (both of which are big parts of the sound of an electric guitar). Simplest way to do this is to lay your hands on a POD, SansAmp or other amp modelling pedal, and use that as your preamp.

Otherwise there are plenty of circuit diagrams available on the internet - whole sites dedicated to guitar effects and amplifiers. Google is your friend (in this case ?).

Brastep, have a look here:
http://runoffgroove.com/articles.html
They have quite a few amp based effects circuits that you could use. I built the THOR, a Marshall superlead style one (as a pedal) for a friend and it sounded really good. Plenty volume (gain) on tap too.
Thinking of building this one http://runoffgroove.com/eighteen.htmlfor myself as a backup and to use as a pre into a little practice amp.

Also have a look here; http://tagboardeffects.blogspot.com/

Attila

It might be easier to buy one of these active circuits

http://www.axetec.co.uk/guitar_parts_uk_083.htm

Psean

Attila Barath wrote: It might be easier to buy one of these active circuits

http://www.axetec.co.uk/guitar_parts_uk_083.htm

Nifty ?

Psean

I suppose you could use an LPB or SHO type boost in front too. No?

AlanRatcliffe

Attila Barath wrote: It might be easier to buy one of these active circuits

Psean wrote: I suppose you could use an LPB or SHO type boost in front too. No?

Both still designed to drive a guitar amp... Without an amp sim of some sort, it'd still sound like you're plugging straight into a hi-fi.

Psean

Alan Ratcliffe wrote:
Attila Barath wrote: It might be easier to buy one of these active circuits

Psean wrote: I suppose you could use an LPB or SHO type boost in front too. No?
Both still designed to drive a guitar amp... Without an amp sim of some sort, it'd still sound like you're plugging straight into a hi-fi.

Ah, so volume-wise yes, tone-wise no.

Psean

Brastep wrote: I recently built an el-cheapo solid-state amp from a kit as a fun project and to put a spare old 8" speaker to some use.

Just thinking about the amp sims and stuff; is it a guitar amp speaker, or a full-range speaker from a radio or something?

Attila

save time and money buy a g-tar amp 7-800 could buy you a cube or a vox solid state

Attila

IMO of course

Psean

Attila Barath wrote: save time and money buy a g-tar amp 7-800 could buy you a cube or a vox solid state

But you miss out on this bit:

Brastep wrote: ...as a fun project

IMO of course ?

Attila

The odds are seriously against Brastrap with this project, make some noise.... sure .....

dont expect much and you will bucket loads of it

Attila

IMO of course

Wildaker

Brastep—which kit is it? If we could have a look at the circuit it might help work out how to make it perform correctly.

Brastep

Hey Guys -- Many thanks for the responses and the useful links. I will follow them up soon.

Yes the odds are stacked against me, but its just a "fun project" and I'm a serial DIYaholic -- Homemade guitar, homemade effects pedals, etc etc.

To answer the last post, the kit is a "Smart Kit 1041-K01" and uses a TDA1515 IC as the core of the circuit.

I also realised after posting that the amp's 20W rating applies to output thru a 4 Ohm speaker, and since mine is 8 Ohm, I should not be surprised by the muted sound!