advice appriciated on two channel practice amp with blend function

[erikb1971]

Hi all

A friend of mine has started building guitars last year. I thought it would be cool to build a small amp for him as a present for when he finishes his first build. That might take a while, which is good, because I want to build something different, as usual. And I am not at all an expert electronics diy. Although I managed to finish two gainclone amps, a neve 1073 mic pre amp and a pultec eqp1 clone, so I am not completely without experience, just without any knowledge or background.

My friend's first project is a dual output Bass 6. For those who do not know, a Bass 6 is a sort of cross-breed between a bass and a guitar, with six strings. Think The Cure's Pictures of You for sound. He is planning on having the bridge element and the neck elements on seperate outputs. That got me thinking. What if I would build a dual channel amp that can play both channels at the same time.  One channel for the neck, one for the bridge. With two speakers so you could actually chose to play stereo.
It would be cool though to also have the possibility to to plug in one "normal" guitar and use both channels at the same time. It might be cool to add a blend control so you can easily adjust the amount of one channel versus the other. Of course it should also be possible to plug in two guitars and play together on one amp.

There are a few parameters on this project.

1. It needs to be cheap. As cheap as possible.
2. It needs to be of at least decent quality.
3. It needs to be small and light.
4. Preferably at least one channel should be based on the noisy cricket, since I have already the parts for that.

So after thinking a bit about this project, I think I would like to add a tone stack to both channels, for versatility. From what I have read, the Phabbtone would be a good choice. But any other ideas are welcome!

Also, because of the blending, I think being able to adjust the amount of amp distortion independent from volume control would be cool. So you could have a clean channel and a distorted channel blended. This could be done by either by adding separate gain / volume controls per channel or by adding a stompbox circuit to each channel for even more versatility...  Again here: input more then welcome.. I just made this up!

Another question is whether to build two identical channels and make differentiations with the setting of gain, tone and drive (I am starting to like adding an OD or distortion to each of the amp's channels), OR build two very different sounding channels (one ss and one tube / hybrid?).

So... that was my Sunday afternoon idea, looking forward to your input!

Cheers

Erik                   

[J M Fahey]

Noisy cricket and Bass are not compatible. Sorry.
I suggest you build 2 identical amps in a single chassis.
2 x 10/15W ones would be fine.
Google TDA2030 , read the datasheets, they have suggested practical circuits , even show one possible PCB layout.
If you don´t want to etch PCBs, Velleman kits and many others offer them.
And mount 2 speakers, at least 8" ; 10" (or even 12") is better.
If you want overdrive/distortion, build an external pedal clone, your choice.
Good luck.

[joecool85]

Juan is right, the noisy cricket just won't cut it for bass at all.  If you don't want to go TDA2030, you could use LM1875 chips, similar in price and wattage and still easy to work with.

[erikb1971]

thank you a lot for your comments... I am going to read in on the TDA 2030. In the meantime... one little thing I would like to have your input on:

1. if I want to build a small amp with the noisy cricket ( I already have all the parts here anyway) and I want to add a tonestack to it.. what is the way to go?

Cheers

Erik

[J M Fahey]

Search for Phatt or Phabbtone here, or just browse the post titles.

[joecool85]

1. if I want to build a small amp with the noisy cricket ( I already have all the parts here anyway) and I want to add a tonestack to it.. what is the way to go?

Cheers

Erik

Use the Noisy Cricket MkII schematic, it has a tone control: http://www.beavisaudio.com/Projects/NoisyCricket/DIY/NoisyCricket_Mark2_BuildGuide.pdf

[erikb1971]

JM & Joe: I am so sorry for not carefully reading your posts! I thought you said that the phabtone would not work with the noisy cricket! But I was not paying attention! That is why I asked again about the tonestack even though I mentioned it myself in the first post. Poor reading on my side.. sorry.

I have seen the simple tone control on the noisy cricket but I was looking for something a little better / bigger.

So since the noisy cricket will not cut the bass I will forget about using it for the bass six. I still like the idea of the two channel blend-able amp though... so I think I will work towards that Idea... but first.. let the cricket and the phabtone come alive!

Cheers

Erik

[Loudthud]

The Noisy Cricket is tweeked to be a guitar amp. It has pretty limited low frequency response and lots of gain. A few changes would make it more bass friendly. Replacing the LM386 with an opamp would give lower noise and a little cleaner sound (as a preamp) but not a night and day difference.

[phatt]

Hi Erikb,,
            I very much doubt you will win this one.
the complex preamp you describe is way over kill for a 1/2 watt Amp.
A bit like building a sat nav for a paper airplane :lmao:

Those small Amps are popular simply because they distort like crazy ,,have no useable bass response.
and can be plugged into a bigger amplifier for crazy OD or used to drive headphones.
Well suited for hard driven leed guitar but about as useless as wet toilet paper when needed for clear stereo bass amplification.

You can of course use it as a tricked up preamp but you will need something much bigger for low frequency.

Yes the PhAbbTone circuit will certainly be a useful unit to have on hand.

I just modified an old Crate V30 and the onboard tone was useless and far to tricky to modify so the owner now uses the PhAbbTone in front cost him far less than modding the internal circuitry.
Also keeps his resale higher if left untouched.
Hope it helps you out.
Phil.