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Zapco/BSG/Ebay deal

29K views 126 replies 25 participants last post by  boarder124 
#1 ·
I tore into the BSG amp last night and thought I'd share some thoughts and pics. I did not get to hear it because I was running late but did get a break out box built and took some static measurements.

Here is the bad Oscar:


And the preamp/ mic Pre/ CROSSOVER!



The amplifier runs on bipolar (duh) 14.8V rails. The power supply is a PWM switching type unit and is NOT cross-compatible for use in the car; it would be VERY difficult to convert. There is a switch in the power supply that I believe sets it up for 220V operation. Next to the power switch and HV rectifier, tucked in there is the Fuse, it's a 6.3A puck style commonly seen in European gear, they are not going to be found at rat-shaq so probe carefully, you will need to order spares from an electronics wholesaler like Mouser or Digikey. I plan to grab some in the next order I make, I'll get a part number.

The finals are 2N6488 and 2N6491 made by ST and Moto respectively. There is one each per channel; they are driven by TIP31 and TIP32 devices that are driven by Central CEN-U57 and CEN-U07 transistors. There is a lot of drive here with little gain, the amp should be pretty stout, the finals are 15A/80V devices so they are certainly running in their SOA.



The amp is fused at 6.3A the manual states that it can consume 420 watts, if the amplifier were 70% efficient this would mean that in theory, all channels driven, one could get 49W/Ch out of it, if it is 80% efficient (there IS a PWM supply) then theoretical output all channels driven would be 56 watts.

The manual states that it IS ok to run a 2 ohm load (they say 4 (X) 8 Ohm speakers per channel)

All this is only true if the power supply is up to the task, these are just figures. The HV pulse voltage of the PS is 166V, rectified and filtered right off the AC line. This is then pulsed and stepped down to the rail voltage previously mentioned.

Getting separate inputs...... My unit was sent with 2 audio cables, fortunately, after demolishing a PS/2 keyboard it was found that my specific keyboard did not have all 6 wires in it, just 4 and a shield. I chose to hack up ONE of the cables and save the other.


I used a small bud box and put 6 RCA females into it, I also installed 2 DPDT switches that gang channels 1&2 to 3&4 and 3&4 to 5&6, this way I can use 2, 4, or 6 inputs. I just did a pigtail end for wiring; I was going to not sacrifice a cable and put the jack out of the preamp in it but decided not to.

Here's the unwired box:



Breakout with the switches wired:


Totally wired:



Here's the finished product:



Big problems arose when becoming confused while looking at the manual for wiring color codes, the manual is screwed. They state the color coding as follows:
Ch1=Red
Ch2=Yellow
Ch3=Blue
Ch4=black
Ch5=White
Ch6= Black!!!!! (WTF)

2 blacks? and there is no white or blue!

Here's the correct wiring!!!

Ch1=Black
Ch2=Brown
Ch3=Red
Ch4=Orange
Ch5=Yellow
Ch6=Green

^^^^^CORRECT^^^^^^

Kinda looks like the resistor color codes eh? Whoda thunk it?

The second method of doing this eliminates the BOB and cable, you will need to drill 6 holes in the amp, I would do this under the speaker outputs, you will not need ground as chassis and signal share common ground. It does not render the stock input useless, it allows for an either/or operation.

IF YOU SUCK AT SOLDERING THIS METHOD IS NOT FOR YOU!

Near the female DIN connector you will see 6 SMT resistors labeled in this order:
R89
R90
R98
R105
R112
R116

See:


With a maximum of 1/16" chisel or screwdriver tip quickly tack 6 wires onto these resistors on the side closest to the input connector. GO FAST with the heat, too much heat will melt the other side and knock the resistor loose, they will re-attach but if you have never worked with SMT stuff it will anger you quickly!

The other ends of these wires will attach to the center conductor of the RCA's you just mounted. The order is as follows:

R89=CH3
R90=CH5
R98=CH1
R105=CH2
R112=CH6
R116=CH4

Now you have 2 different methods of inputting to the amp. Don't use both at the same time as the preamp won't like having signal applied to the outputs!


So there you have it!

Time for a reward!


Enjoy

Chad
 
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#77 ·
Hell if I know, but I've felt amps run a lot hotter for a longer time :)

Thing is that the WHOLE amp gets hot since it's a brick of aluminum and nicely bolted together, it nicely ironed (pressed) the carpet on my bench :)

Chad
 
#78 ·
chad said:
The Behringer will do just fine. Another cheapo but good analog crossover is the samson S-3way.

Chad
The cheapest place I found for that Samson is about $60 more expensive than the Behringer still... :( But I haven't looked hard enough... ;)

Never used/worked with any Samson gear before, Are they decent?

Thanks.

Leo
 
#79 ·
The samson is about the same as the behringer quality wise IMHO. It has metering, phase reverse per channel, mute per channel, and limiting although i don't care for the limiters, the release is too slow. It's also got CD horn EQ but i don't use that either. i like the samson because of it's WIDE Xo freq selection. I got a helluva deal on it at the time :)

Chad
 
#82 ·
So guys how is this little amp turning out, i have 2 sitting at home and i'm going to pick them up this weekend to start messing around with. What can i expect from them, i have 2 and i want to pretty much run a 3way stereo setup in the future.

First off though i think i'm going to modify slightly my bookshelfs to run them active by the dcx2496 i'm going to buy.

How would i eventually go about bridging both amps to a 3way mono signal on each amp, so each amp would run each side for the 3channels .

Also is this truely a zapco styled or origin amp, What would be some background on this particular amp as well as the BSG/zapco connection.
 
#83 ·
Turning out well, it play's suprisingly loud, is free of any strange noises and will do quite well in your situation. Read around, there's a couple ways of making the channels work or PM me and I can give you the skinny. It bridged nicely albeit you have to accurately set the levels, there's no ganging switch so a good voltmeter and tone are in order.

Chad
 
#84 ·
chad said:
Turning out well, it play's suprisingly loud, is free of any strange noises and will do quite well in your situation. Read around, there's a couple ways of making the channels work or PM me and I can give you the skinny. It bridged nicely albeit you have to accurately set the levels, there's no ganging switch so a good voltmeter and tone are in order.

Chad
Will do when i get a few minutes, hitting the books pretty hard right now.
 
#85 · (Edited)
Ok, I got mine up and going and I have to say, Im impressed. Very good sound quality and decent power. More than enough for my apartment and setup.

I have mine set up as a 3 channel amp. 1 left, 1 right and 1 mono rca input. All the channels are bridged. I didnt have to buy anything but a female rca input set at radio shack for 4 dollars. You dont even need the female input if youre ok with 3 stereo channels. It was very easy so I'll break it down for those who want a similar setup.

First thing to do is unscrew the worthless preamp and open it up. Then remove the circuit board inside. We only need one part of that but we'll use the box as the preamp chassis.

We are going to use the provided rca inputs on the preamp and the box the preamps in. Disconnect the red rcas from the circuit board. Youll see where to cut. Then your board should look like this



You dont need the board again and its not going back in the box. Now cut the ps2 cable and strip it. Youll have 6 colored wires and a bare wire. This cable enters through the ducking level opening on the preamp cover.

Ok, so now we solder following Chads guide on color.

For a stereo and mono input:

Reattach the rca input to the preamp cover with the screw. Make the rca's soldering points attachents visible. Youll see the input is the nice long tab you have to solder on the upper part of the rca and the ground is underneath. we solder channels 1 and two to the red rca input (the top connection on the rca) then solder channels 3 and 4 to the white rca. Solder the bare wire to the grounds of both rca inputs.

Then get a female rca input, (I just went to radio shack and got a gold set for $4) and attach it to the preamps cover in the "output" hole. You probably have to find a washer as the hole is too big. I found a bolt that worked well. Solder channels 5 and six to the same input and run a wire from the stereo input's ground to the mono rca ground. This pic should help explain and show you appropriate colors. Excuse the sloppy solder. I had to resolder when I added the mono channel.



Then screw back the cover and your preamp is ready. It should look something like this.



I used some brushed aluminum contact paper I had (found at lowes) and just covered the rear preamp cover with it. No more holes and it made a nice finish if you want this to be visible. Otherwise this preamp could be hidden.



Here it is in its home powering my left and right and center (mono) using my Marantz recievers 7.1 preouts.



Make sure all the gains match.

The sound quality is excellent and far superior to my marantz reciever's built in amp. Much more detail and seems clearer. Suprisingly loud and powerful at the 60x3 its rated for. No problem powering my speakers.

You might first get a horrible buzzing noise when you first plug in your amp and connect it to speakers. Thats because your reciever and the amp uses a different ground. Get a 3 prong to two prong adapter, or just pull off the ground prong and the noise will be gone.

Hope this helps some people. So far I have to say this is the best ebay deal as of yet.
 
#86 ·
JR DIY Alert!!!!! Yall are gonna be proud!

We got our 6 year old son a boom-box for Christmas, the standard Sony Fare with Radio Cd, Etc. He was stoked for a bit but he thought it sounded bad, and it does. We have bred ourselves a mini-audiophile :)

In the quest for something better I told him he would have to work to get what he wants and that we would use things that I purchased cheap, traded for, or were lying around. And off we went this weekend. We have been trading Labor services for equipment, gotta teach them commerce early :) And you can now eat off the shop floor, and for months to come ;)



Keep in mind that this gizmo was COMPLETELY designed, assembled, and painted by a 6 YEAR OLD! Since he can't read fractions on a tape measure (hell, he can barely read) he used the actual devices or a dowel to measure cuts for the table saw. He set the saw up and I made the cuts, in fact the only thing he did not do was guide the router and make the cuts on the table saw. There's 5 chunks of wood here total, all measured by the components or a 1/4" dowel :) He did all the gluing, clamping and brad nailing. Then after shooting a few brads where they shouldn't have gone he did the bondo work after I ground the brads out into the wood. Fleckstone paint was used to cover imperfections and it did not turn out too bad. So here is his creation!




We used a surplus switch mode charger originally intended to charge Lead-Acid cells. I modded it to make it think it is a power supply and it makes 12.5V at 3.5A, more than enough to power the headunit, the amp has a built in supply. paired it up with the Insignia speakers (50 bucks a pair) and Wola! His new Rig........ Almost... (read below)




Now for the Almost..... He wants a sub (lets see him measure that box out with a Dowel :) )

He wants to do some horse trading, he has in his possession the Breakout box I made up for this amp and a spare stock preamp (no spare interconnect cables other than the "phone plug") I plan to just install RCA's on the amp so the break out box is not needed. He is wanting to work out some sort of trade for a 10" or larger 4 ohm or dual 2 ohm sub driver that MUST be rather efficient, work in a vented enclosure, and not look "girly," The Girly thing is straight from his mouth. Anyone need a breakout box and have a spare driver lying around? We can work on Shipping charges since the driver is much heavier than what we are shipping.

Chad
 
#87 ·
Man, this is super badass. :)

If this was a little while ago when I was giving stuff away I would find a way to ship you one of the subs I had. I gave away a SS exact 10 4ohm and a Diamond Audio M5 10" DVC4, both work very well in small ported boxes.
 
#90 ·
Chad,
That is awesome! Great job by your son! You must be really proud! :D

I just pulled out a Boston Rally 10" (4 ohm) sub from an old install of mine. It's in a nicely tuned bandpass enclosure (designed & built by me), is very efficient, and sounds pretty darn good IMO (for what it is). I had told another buddy that I would sell it to him; but let me double check with him on that. (I haven't talked to him in awhile) I'll get back to you, but this might be an option.
 
#92 ·
MaMa was sick this weekend = Crabby = Men in the shop/garage cutting wood and tearing **** up :)

He's pretty handy with his hands and can pretty much put together/draw (roughly) what he visualizes, that helps. It's fun to watch him go at something because a youngster's thought process is so much different than ours, and sometimes makes more sense. For example, to cut the bottom/amp shelf what do you do? Slap the amp on the table saw and cinch the gate down. Next, sandwich the H/U between the wood, take your trusty dowel mark how high you want the sides to come up, holler at dad to cut the dowel with the miter box, use the dowel to measure the gate for the table saw, cut two peices and grab the clamps! Caveman style, not one measurement taken that involves numbers. Recess the headunit? Sure! Slide the unit in (damn there is a gap) slide it over, measure the little square off to the side (2 more dowels), measure, cut, slip that in, glue, clamp, nail. While that dries slip the head in trace the trim ring and it's "careful time" with a small chisel and hammer.

The drawback is the "now factor" with a kid, glue and paint needs to dry, thankfully he has an imeasureable love for the shop vac, he cleans up, I whip up a power supply. Off for dinner, screw around for a bit, work on the "mousetrap challenge" (don't ask) and it's paint time, paint it, whip up a drying rack from scraps, and bedtime.

How to keep a kid busy 101 :)

Chad
 
#94 ·
I hate when kids are better than me.

That kid has some serious aptitude.
 
#96 ·
I swear this the last mod :)

No more need for the breakout box! Here's why and how.

Why? It's clumsy and there's enough room inside to work ;)

Here's what you do (the second type of mod from the first post.) I only needed 3 inputs but by drilling 3 more holes you can have 6, and yet 3 more holes then you can do bridging/un-bridging via little toggle switches.

I'd like to preface this by saying more precautions need to be done here, the solder points are very small and a well controlled iron/small tip are needed. I used a Weller WTCPT station and a Weller 1/16" "screwdriver" tip and a steady hand. Also you will be drilling and finishing Aluminum, it can get everywhere, the amp is comprised mainly of SMT stuff and even a metal filing laying across a component or wedged in some op-amp legs can have devastating effects. So do this after you take the bottom off!!!




That's right, mask off the area where you will be drilling, then cover and mask all the internals. an air supply can be handy to GENTLY blow stuff off as out work while holding the amp "open part down."

Punch your hole guides:



Drill and install RCA's See the metal shavings I was talking about? I like to drill a pilot hole then go at it with a unibit, I pretty much always drill everything but unibit holes on the drill press so the unibit saves oodles of time, the RCA needs a 1/4" bit. The Chassis is signal ground, no grounding is needed.




Now, this where you will need "The Knack" see: http://video.google.com/videoplay?docid=2021369175979347037 You will be soldering to surface mount components, it's not fun but with the right tools you'll be OK. At least the amp was not expensive eh? Mua Ha Ha Ha :) Measure out the length of wire you will need to go from the SMT resistors by the original input to the RCA's These resistors:




Then strip one end at about 1/32 of an inch and the other at about 1/4" Tin them. the 1/32" is the more important to do right, you will want great solder penetration and a little blob on the end without the little "DairyQueen" sharp point protruding made of solder (love those engineering terms.) Next locate the input side of the resistor (side closest to the original connector) Add a small amount of solder to the input side of each QIUCKLY as to not heat the whole device and pop it off the board. You will want a shiny "blob" there about twice the size of the original. Go fast and keep a steady hand. The order of the inputs on these resistors is in the first post of this thread, note that it is rather unconventional but makes sense if you know the pinout of a PS/2 connector. Work from the top down, it's easier. Approach the new connection with the 1/32" stripped and nicely tinned wire, just before you touch the SMT pad apply heat to the wire and the instant it penetrates the blob on the board remove the heat. Hold the wire steady as it cools. Give it a tug (lightly) to make sure it's on there and then wire the RCA up (much easier) The tug and moving while wiring the RCA will give it a good test to make sure it's gonna hold.

If you have never done this before and want something to practice on then use the preamp, if you are not going to use it. Just practice tacking wires to your little heart's content.

So "rinse lather and repeat" the other 5 input resistors and you will have something like this:



I used the signal conductors from some scrap Gepco 61801 I had laying around after I copped a bunch of the drain wire for another project, you will want to use some pretty small stuff, I recommend stranded, and NOT gutted network cable, I've had bad luck with the solder holding and the wire breaking on that stuff.

When you are done you will have this (or more RCA's):




Women will flock to you and you will gain popularity at the lodge/golf course.

Chad
 
#98 · (Edited)
If you're bridging, say channels 1+2, do both channels need input, or do you only need to input on channel 1, or 2?

Edit: Also, for those of us that suck at soldering (read: me), would it be possible to pull off that metal sheath over the 6-pin input and just solder onto the wires in there, instead of the board itself?
 
#99 ·
solacedagony said:
If you're bridging, say channels 1+2, do both channels need input, or do you only need to input on channel 1, or 2?

Edit: Also, for those of us that suck at soldering (read: me), would it be possible to pull off that metal sheath over the 6-pin input and just solder onto the wires in there, instead of the board itself?

(1 AND 2) not (1 OR 2) and the levels have to be matched really well (preferably with a scope or voltmeter) for best efficiency. Since you will be using the two internal positives of the amplifier (to double voltage) each channel will need to receive the same signal (the even channels are already phase inverted).

Pulling the 6 pin out would be a rough job, the amp board will need to come out of the sink at which time you risk damaging the Sil Pads for heatsink conduction and pulling your hair out. Count on HOURS of work for this. If you decide to go the "get-er dun" route and force/break the connector out then you risk damaging the board and you are in worse shape then screwing it up. If you are truly bad at soldering or don't have the tools, the break out box is for you. The boy (my kid) has one for trade :) If you can get the sheath off without damage (i think it's soldered to the board) then knock yourself out, it will work fine!




See the solder point for the sheath right next to the right-most 10K pot? It's ground for sheilding purposes.

Chad
 
#100 ·
Hey guys,

I just chimed in here from the Xlobby forums, where we've been discussing this amp...more towards connecting to it without the AIP. Most of us are using it in a music distribution setup. One guy has set it up in a DIY projector system as well. Pretty cool.

Chad, I just wanted to say, great job on the review and the mods you've done to the amp, and your son is very talented indeed. Also thanks again for letting us know over in the Xlobby forums of this post here. Excellent read.
 
#101 ·
Marbles_00 said:
Hey guys,

I just chimed in here from the Xlobby forums, where we've been discussing this amp...more towards connecting to it without the AIP. Most of us are using it in a music distribution setup. One guy has set it up in a DIY projector system as well. Pretty cool.

Chad, I just wanted to say, great job on the review and the mods you've done to the amp, and your son is very talented indeed. Also thanks again for letting us know over in the Xlobby forums of this post here. Excellent read.

Thanks and congrats on joining, feel free to gander around, please. There are some sharp cookies here as on your forum, even if car audio is not your bag. It's nice to have you, enjoy your stay. We sometimes wander off into home and pro audio too :)

Chad
 
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