The ware for June 2006 is below. Click on the picture for a much larger image.
Hopefully this ware isn’t too easy for the readers; it’s more of a fun ware than a difficult ware. There’s a little bit of a story behind this one…I had to open this piece of equipment up about a month ago to replace the fan, because it was making too much noise for its intended application. So, I took a couple pictures and figured I’d share it with everyone. Bonus points to anyone who can figure out the make, model and power rating for this ware! Next month when I post the winners hopefully I’ll have a fun clip to post that is related to why I was fixing this ware.
8-channel (7.1?) power amp in the 100W/channel range. A reasonably-nice one with a toroidal (self-shielding) power transformer and discrete push-pull transistors in the PA stages. (Although oddly enough, most consumer gear I’ve seen has moved away from the power-IC trend it seemed poised to adopt a few years back. I guess the cost savings didn’t materialize.)
This one’s 5+ years old, if the stamps atop the filter capacitors are date codes. Googling the 1724-330A part number (without the obvious -0001 revision identifier) yields some tantalizing 404s on a couple of consumer service sites. If someone could dig up an archived copy of the first hit — http://www.cdlens.com/gfx/download/price_list.xls — it would probably solve the puzzle, the same way my HP 8568A was identified earlier. :-P
I agree with John Miles in that it is an amplifier.
Having never taken one apart personally, I speak purely from what little I’ve seen of my father taking these apart and what I’ve seen in DIY / kit books etc.
I’d say it’s a 4 channel (total) amp with some form of preamp for each channel.
(IMHO there’s not enough “big” stuff (capacitors mainly) for a full 8 channels – even though there are eight power transistors.)
So… we have:
1. A separate power supply off to the left-top
2. Toroidial power transformer
3. Two somewhat powerful amps
4. Massive amounts of heatsink
5. Two somewhat identical channels
6. Seriously heavy cables from each side to what seems to be the output board (at the top centre)
7. Two small light duty inputs at the bottom right.
8. A relatively simple control board (top right)
Also, the amps on each side seem to be almost identical in layout and components, however:
on the left we have:
9. A separate lead from the power supply (three wires, black – middle right of power board => left side, same horizontal level as the ribbon cable)
and on the right we have:
10. the ribbon cable
11. a couple more big resistors
12. the input circuitry (7)
I’m guessing that the control board (8) is volume controls for both amps, and preamps, maybe with some other simple controls.
So…
My first guess was that this was a mid-high end consumer grade 4 channel amp – however, the simplicity of the controls and the fact that the outputs are on the front throws this right out the window.
I’d say that this is a mid to high end 2x stereo channel PA amplifier with preamps.
Why…
Separate power supply (1) and the power transformer (2) seem to indicate that the designers wanted to:
– Reduce noise in the amplifiers
– Simplify the design of the amplifiers
– Re-use existing components.
The powerful amps (3) with their huge heatsinks (4) indicate PA, as these usually have a high output power. The chunky output cables (6) back this up too.
The simple control board (8), the two identical sides of the amp (5) (this can also be seen in the design of the input circuitry (12)) also back up the idea that this is for a PA system.
If we look at the two sides, we can see the same components and pattern of components down both sides:
– the round coils
– four big caps
– the three odd looking components (I can’t identify them)
– the four white boxes (resistors)
– and the 8 power amps / transistors on each side.
This is then echoed in the input circuitry:
From the bottom:
– the two input sockets
– the red cap
– the two blue caps.
This again screams PA – why else would you want two *identical* amplifiers – no surround amp I’ve ever seen uses identical amplifiers for *all* the channels. (front always has more power, and the sub is usually different again from the surround channels)
As for the differences:
it makes more sense, for me at least, if the inputs are on one board, that the controls should go there too (10) – then, split up with the audio signals to each amp. – and as this is all there, then there would be more circuitry to power the input board (11), and from this whatever power source is needed for the controls would presumably be derived. This would be why the left side needs it’s own cable from the power supply. (9)
Another thing to notice is the simplicity of *everything*. There’s *no* fancy circuitry *anywhere* – no soft power, no crossovers, no nothing – again saying PA, not consumer.
Apart from the power wire to the left side, the entire system is really modular – the two amplifiers are only connected to each other by the black, socketed, ribbon cable at the bottom – indicating that either could be easily replaced, and the power supply is also separate, again easily replaced. Not only this, but almost every cable is socketed – again indicating easy replacement of parts if needed.
As such, my final answer is that this is a PA amplifier, mid to high end, two channel, with preamps. Though I’ll hedge my bet by saying that it could also be a high end guitar amp, but this is unlikely.
Julian Calaby
I agree with everything Julias has said, I just wanted to add that, by chance, I found something that really matches the layout of that ware on the first site I looked for:
http://www.behringer.com/EP1500/index.cfm?lang=EN
or
http://www.behringer.com/EP2500/index.cfm?lang=EN
The potentiometers for adjusting the gain/volume are on the front right, there are two LEDs per channel.
On the rear also everything matches quite nicely. Sockets and screw-terminals for output, circuit braker and AC input, XLR and 6.3mm “Headphone-type” (german: Klinkenstecker) connectors.
So that makes this a 2x700W or 2×1200 W PA Amplifier.
And, the “three odd looking components” most likely are potentiometers to adjust quiescent current of (in addition to the front panels) gain of the amplifiers.
It’s a big two-channel amp. Two channels because you can see the fat output wires between the amplifier and the speaker connection block. There are only two of them.
Do we have MOSFET output transistors?
– looks like four pairs of transistors are paralleled in each channel, which is normal MOSFET design.
– I don’t see thermal compensation diodes to prevent runaway, but wait, what’s that to the right of R153?
– There are fairly large emitter degeneration resistors, a feature of bipolar design.
– To drive this many bipolars will require beefy driver transistors. Would Q105 and Q106 be strong enough? They’re on the big heat sink, so they can dissipate as much power as they need. The main limitation is safe operating area. I guess it is possible for TO220 parts to drive bipolars.
The rear of the amp is in the top of the picture.
On the lower right (front panel) are level pots and a preamp circuit (see the two socketed opamps). Also looks like some clipping indicator LEDs.
It’s a high volume product (where single-sided circuit boards make sense) but not the cheapest possible (silk screening, blue circuit board costs a few pennies). Circuit boards are snapped apart.
Inputs on the upper right (back panel) are XLR and 1/4″, so this is definitely a pro audio product.
What would the front panel look like? From the left, we have blank space, then the power switch (rocker), an LED for left channel, vent for the heat sink tunnel, two LEDs, left channel level control, two LEDs, right channel level control. I don’t see rack ears, but maybe bunnie didn’t install them for some reason. I don’t see handles on the front, but I see on on the back near the power entrance. Googl e image search isn’t helping me.
What does the back panel look like? From the left (in the photo), handle, IEC power entrance, circuit breaker (15A! This is a high power amp!) power output (which is four binding posts in a vertical row and Speakons) then the fan (shiny grille) then inputs (1/4″) then inputs (XLR) then … is that speaker level inputs? looks like spring connectors on a cheap hifi output!
hmmm, Google image search and ebay image search ren’t giving anything. Can I narrow the search a little bit? bunnie would own something of reasonable quality, right? Look at crown, crest, mackie amplifiers on ebay / google images. No.
Let’s look at musicians friend. Aha! There it is. The company name is 679035a498d402191f915ec9dd25e4b4 (md5sum of name+\n)
The model number is hard to say: there are several amplifiers in the series. I will guess
95098f76ca0945dc0b846befcad69328 as this is the highest powered class AB amplifier. The higher-powered ones are class H, which involves a switching power supply. Looks like this amp only has a linear supply.
I found the schematic for this guy’s little brother online. The output stage is bipolar. Looks like a straightforward Sziklai output stage.
I redacted the company name off the schematic at put it on my website (this is only one channel):
http://vivara.net/images/schem.png
So the little brother uses only six output devices, which confirms my guess about this ware being the larger class AB amplifier (eight output devices). It wouldn’t suprise me if the same circuit board is used in both models, with two devices not populated in the smaller model.
This is a great post, I really am enjoying your blog. Just thought I should say you’re doing a great job.
it is a qsc rmx2450 or a Behringer ep2500 most likely the ep2500
its phonic2500 : 2x500w (4ohm) toroidal transformer 800w bipolar transistors
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