Achieving "Vintage Sound" with Mini-LM386 Guitar Amp?

[TheLaw117]

So amdist my main amp/speakers project, I kind of wanted to make a family member, who is a guitarist, a mini amp (as a birthday present).

He knows his history, so I thought I'd entertain him with a DIY vintage Fender replica. (Yellow tweed and brown grill cloth).

Along with the looks, I want it to sound good, and preferably like a Fender Bassman circa 1959-ish. I'll be using an LM386 (Ruby) with the Bassman mods. I think I could etch the board, solder it up, cut out the box and wrap it in tweed in one Saturday..so it should be a quick project.

I'd like to use a 4-6inch speaker, and I'd like the driver's cost to be <$30 preferably. Parts-express is my favorite supplier, but if you have any other ideas (that ship cheaply in the US), I'm open for them. So is there anything driver in particular that might suit the bill. The HiVi M4N, M6N are among my favorite drivers. They might be a bit too bright for the application, but I'm not sure.

Also, for the amp's components. My current selection would be. Wima for the film. Carbon comp resistors. Panasonic FC/FM electrolytics. Conductive Plastic pot. Any changes there, or ideas?

Thanks.

[PeteMcK]

a guitar amp needs a guitar speaker, hi fi drivers are useless in this application.
Paper cone, corrugated surround, highish Q, peaky upper response & reasonable power handing are required, Here's an 8" example: Peavey 8" Blue Marvel Guitar Speaker 4 Ohms 70777221

[TheLaw117]

Well I'm not too familiar with guitar equipment. So it would be better to use a "guitar speaker" versus a "hifi driver"? As in, would the sound be different? The power handling requirement on this one is about 1W...just saying...

[PeteMcK]

the sound would be dramatically different. Some drivers used in 'ceiling speakers' have similar characteristics to guitar speakers, & may be a suitable substitute for a low power amp

[chris661]

Hi,

I've found that adding an output transformer to a SS guitar amp can help with the "vintage" sound by raising the output impedance. This allows the speaker to exhibit its own resonances etc (its tone, if you will), by reducing the amplifier's "grip" on the speaker cone.
I used a mains transformer with dual secondaries, connected the amplifier to one secondary, the speaker to the other. Sounds lovely.

Guitar speakers are different from HiFi speakers: most 8" hifi drivers will have a low(ish) resonance, designed for decent bass response, and a reasonably smooth response above that.
A guitar speaker will have a very light cone, which raises SPL@1w and resonant frequency. But that's okay - low E on a guitar is 82Hz so there is no need for ground shaking bass. Further up the frequencies, a guitar speaker's midrange response will have engineered in some peakiness, as that's what various speakers gone before have had, and people liked that sound.
For a vintage sound, look for a speaker with not a lot above 3-4kHz.

Chris

[TheLaw117]

how about something like this: Weber AlNiCo Signature 6x9" Speaker

[AstroSonic]

"He knows his history, so I thought I'd entertain him with a DIY vintage Fender replica. "

The LM386 based amps are 'cute', but have only remotely similar sound to the real thing. If this is acceptable, then I concur with the previous post regarding guitar speakers. The Peavey on special at PE is an excellent buy. Also consider one of the offerings here:

Angela Instruments Online Catalog - Speakers

You should use a plywood baffle board (sounds better than MDF).

If you want the historic looks AND sound consider this project (the real deal!):

Single 6V6 Guitar Amplifier Project

The overdrive sound so popular with these amps comes from a combination of overdriven tubes, the output transformer and the speaker (a guitar speaker).

Good luck with your project!

Bob

[TheLaw117]

Well it's just a birthday present. Not like he's going to go on tour with it...By similar sound, I don't mean dead-on, but something that might remind you of it. Nothing more than that really.

What does anybody think that you could tell the difference between an AlNiCo magnet and a Ceramic magnet in this application? I'm contemplating what to get...

Thanks!

[madtecchy]

hi Law.
Forget hifi when building a guitar amplifier. Guitar amplifiers are part of the instrument the distorsions and nonlinear amplification all add to the sound .

regards ian