Acoustic 470 Guitar/Bass amp

[unicorn]

Hi, Could anyone please help point me to a readable circuit diagram for the Acoustic 470. Amp has been out of action for a few years and i dragged it out of the shed to check out for restoration. Still have the original bass cab with 2 x 15" Celestions.
Thanx

[Phostenix]

Check out this thread:
http://music-electronics-forum.com/t14153/

[unicorn]

Acoustic 470

Hi Phostenix, I checked this one and found it to difficult to read, even spent time with my brother in a pic program to bring it up but no luck. I'll keep searching. ( I did consider building a different power amp stage but would rather keep it original)
Thanx

[Phostenix]

Are you having trouble reading it on screen with Acrobat Reader or when you print it? You could purchase the schematic from musicparts.com (their watermark is on the schematic). I have the Acoustic 370 set from them & it's very readable (split into two 8.5 X 11 pages). It also includes the service manual & parts list, etc.

$20 here (Paypal):
Acoustic*Schematics

[gbono]

unicorn,

Check out this site unofficial acoustic control corp forum - Message Board - Yuku

If you need a schemo I can email you one - just went through one of these so ask away if you have questions.

[Phostenix]

... just went through one of these so ask away if you have questions.

Did you get that working?

[gbono]

Yes, the PA board had a few issues but what threw me for the longest loop was the fact that I used replacement covers on the output devices (TO-3's mounted on the back chassis panel) that kept the collectors from making contact!!! I'm very familar with the design of this amplifier now

[Phostenix]

What covers do the output transistors have? I have a 370 that will be my next project (& another one on the way) and it looks like your basic TO-3 socket. The 470 must have different mounts, so I'm curious.

[gbono]

check out this link and scroll down until you see real pictures of a 470 - can't miss the covers on the EXPOSED output transistors. You do not have the same mounting scheme on a 370.

GuitarHeadOrBassHead470 < Acoustic < Wiki

[Phostenix]

Interesting. I'm not familiar with those covers.

[J M Fahey]

I have the ones that work: 1 of the screw holes is 1/8", so the screw head keeps it firm, but does not touch the TO3 metal , and the other is slightly over 1/4", so the head slips through and makes contact with the case.
Haven't used them for ages.
That 470 is a mighty fine amp, but please *always* use the Guitar/Bass switch on "guitar". All it does is place a treble-killing choke in series with the speaker, muddying the sound innecessarily.

[Jazz P Bass]

Acoustic 470 SM

Here is the service manual.
I got it from MusicParts.
I workrd on one of these a while back.
A real rats nest.
Enjoy.
John G

[unicorn]

re 470 Acoustic

A big thank you for the info. I have taken out the output board and drawn my own version of the Power Amp stage and have posted it on KENLINX - bbs.webhop.net. I have now repaired the amp to its former glory and the sound is awesome. We had been using a 250 Watt Jap amp with one 15" and two 10". The Acoustic 470 leaves it for dead.
Cheerz

[vistacruiser]

Remember 476

Unicorn,

Just read about your 470, glad to know it's working!
I just wanted to say what a great bass amp you have there. I had one with the 2-15 406 cab also. Played a j-bass through it in a rock band. A great sound and "fun to mess with" controls. When I listen to the recordings of my band from that time, late 70's, It makes me wonder why I sold the amp! Sounds like you'll enjoy yours too.

Brad

[unicorn]

470 Rig


Thanks Mate, I'm actually a guitar player who likes to have a jam on bass occasionally. I have an old '69 Les Paul bass that sounds almost like a double bass through the Acoustic 470 (awesome). Our bass player now uses the 470, won't even look at the other thing he used to use.
Many Cheerz