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Messages - PhredE

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Amplifier Discussion / Re: Mod a Squire SP-10 amp.
« on: March 07, 2015, 11:30:33 AM »
...Sorry about the long post  :-[

Amplifier Discussion / Re: Mod a Squire SP-10 amp.
« on: March 07, 2015, 11:18:01 AM »
Hi guys.  Yes, definitely the speakers are the single biggest difference. There's nothing that messes up good tone and sound projection than a cheap and nasty speaker.  Those things that are included in Fender's low-end amps are near criminal.

My box measures 25.5"W x 19"H x 11.5"D. It's solid wood (no MDF), and has no covering(s).  It weighs about 25 lbs.

I used this guy's design as sort of a rough template:
On the surface, mine appears pretty similar but I added some other finishing touches in the end.. AND, mine is airtight [eg. not ported].  I covered the sides and back with some water-based polyurethane and will probably just leave it that way. Later I may change my mind and try my hand at some tolex covering or the like... haven't decided.

Speaker is a 12" 8ohm WGS (British Lead? - ugh, I'll have to pull the back and double check.. )

I used solid pine boards for sides+top and bottom. An example of the side boards used:

For the front baffle and back I used what are edge-glued 'panels' of spruce (the individual boards are roughly 2-1/2" wide). The panels are available as 24"-30" wide by about 48"+ long I believe.  Plus, those panels are kiln dried and glued together -- very stable material to work with.  Just like a quality acoustic instrument, a solid spruce (or cedar) top makes a lot of difference in overall sound/tone. 8|  Here is a link to one available at the orange+white mega store:
(these are currently available as pine, although when I got mine there about 1 year ago, spruce was available so I snapped one up).

I ran about 12" of 14GA speaker wire from the speaker connectors out to the 1/4 jack on the back panel and all connections are soldered. 
On the inside, I used spruce furring strips and everything was 'screw and glue' construction.  Oh, I also had a good supply of those old school acoustic tiles used in every band room in every middle or high school in the country (well, when I was in school... :lmao:), and I lined most of the interior surfaces with that stuff too.  I installed a set of casters, a strap handle and a metal grill -- the basic stuff to make it more robust and usable. 

Overall, I am very happy with the result.  [To me] It sounds amazing!
As Fender-type single coils+Fender solid state produces much twang / high-end screech if not reigned in, I designed the box around getting LOTS of low-end -- which it does.  In fact, the low-end is so great, I have to really tame it by dialing-in the EQ carefully.  It takes some time to get the tone 'right', but this box does it.

I will grab a few pics of the rehoused amp unit and the custom speaker box. I may not post them back up here today, as it could be a busy weekend for me, but check back I will get some pics up here eventually.

Amplifier Discussion / Re: Mod a Squire SP-10 amp.
« on: March 06, 2015, 01:21:05 PM »
Greetings. I'm a newbie here. 
Happened upon this thread (and your terrific forum) via Google!  Su-weet, I like it. 

..Wanted to post a related thing I was working on (purely for fun and recreation).  Kinda similar, a bit different, but I digress..

I was given one of these SP-10 amps recently by a brother that was cleaning house.  I wasn't very excited about it at first, but decided, 'well, I've got an extra amp I can tinker with and tweak a bit.' .. So I did.

Basically, I re-housed the guts of the amp (transformer, switch, main board, and added speaker output jack) from it's original MDF+tolex box, into a solid die-cast aluminum enclosure.  And, I can't exactly explain the reason for the improvements, but the result surprised the heck outta me!  It's LOUD and the tone quality is good (surprisingly good, even when amp is pushed up to the 80% range or so of max output).  This amp going into the same speaker cabinet is EASILY produces more volume than does my other 15W Fender SS amp.  (These are both 'practice' amps - no giggling for this recreational guitarist at the time being).

Background stuff:
Let me offer some housekeeping type details here -- so readers can see a few more details and the context, etc. I've owned a pretty good variety and type of amps throughout my 50+ years (Fender, Carvin, Yamaha, Vox, etc), at some point, got kinda tired of dealing with/replacing tubes... expensive, fragile, inconsistent quality... so, I've learned to adapt my sound/tone via pedals/preamps/'gadgets' and go forward with a solid state power amp. Oh, finally, I am definitely no expert on the subject of electronics -- standard disclaimer applies! 

I just drilled holes to in the face of one side of the enclosure to be able to move the entire IC board in one side and poke the shafts of the volume+tone controls through holes.  Then, I just put the nuts on and fasten the one screw (or bolt?) on the back of the IC board up to the top of the enclosure (for support).  The board is fastened quite securely.
Also, the audio amp chip (TDA2030a I believe) is mounted on a small separate 'standalone' board with a capacitor.  I drilled a hole in the top of enclosure and bolted it firmly there.  Imagine: a near-infinite heatsink!

Enclosure used: Hammond 1590F Aluminum Diecast Case 7.4" x 7.4" x 2.65"
Parts Express  #320-754
(this is just large enough to fit the IC board on a side of the enclosure).

Output to an 12" 8ohm (measured at 7.2 ohm) WGS speaker in custom built enclosure (by yours truly).

I use 14GA speaker cable (not hardwired) to run to the speaker cab. and I installed an 'old school' 1/4" jack on the side of the enclosure.  Pretty basic, pretty simple -- but it works well enough.

More on the 'guts' and design of the SP-10 if you're interested..  The audio amp IC is a TDA2030a (long considered obsolete) and has a supply voltage max. of +/- 22V.  I haven't found a schematic for this critter (only similar, but not exact same units), but by many deductions/inferences, it appears the transformer has a secondary voltage of somewhere between 16V and 12V; maybe 14-14.5V?  I haven't measure it directly [yet]. In addition, there are two JRC 4558D op amps (used in the preamp section?), and these are rated for a supply voltage of 18V max.  Every other component is a resistor and/or capacitor and/or a diode.

Fender (Squier) rates the built complete amp at about 10W output nominally.  However, the TDA is capable of producing quite a bit more actually.
Datasheet here:

a). there may be a possibility to swap out the transformer and replace with one having a slightly higher voltage, to get more overall power.  The TDA2030a and JRC4558D's can handle it -- at least in theory.

b). Haven't tried sending signal out to a 4ohm load, but will do that in future tests. Right now, the 8ohm speaker sounds fantastic to my ears.

I really can't offer any good explanation why the sound is more/better, but I might offer observations:  for sure, there is less RFI getting inside that case!  Also, I think the heat generated by the TDA2030 is being dissipated relatively efficiently... maybe these don't matter..? I don't really know.

I will try to add some pictures if anyone is interested.  Haven't taken the time to get those and transfer them, but if people are interested I don't mind doing so.

Finally, let me add that I prefer "Fender type clean tones", so I prefer some light breakup, but believe most of the true 'magic' in guitar tone is just as much a product of the hands and fingers as much as amplification.  I use a tube preamp (juggling between various 12AX7s and 12AU7s; with a NOS RCA 5963 being my favorite) and will readily admit I use a Joyo "American Sound"  amp emulator/boost as well.  Guitar: Peavey Predator (mostly stock, circa 1993).

PS. Sorry about the long post.  Just wanted to offer some info that might help someone out.

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