Pioneer Spec-2 in the lab...

[Pacific Stereo]

Well, I've been having fun with a Spec-2 rebuild. This thing came in blowing the 12A mains fuse, and initially I thought the worst. I expected to find shorted (and very expensive) output devices. But it turned out to be a stupid shorted pipsqueak 1A diode in the power supply (!) taking the fuse out. When I got it, it looked like this (sorry, my camera didn't focus quite correctly and I didn't know it until later):



Dirty, ugly, cooked. It received a total rebuild on both amp boards, power supply overhaul, power meter driver board overhaul, disassembly and repair of all four large relays, new bias relays (this is an adventure, as originals are NLA and there are no modern equivalents with the same pinouts), Wifa film input caps, new pots, replacement Unobtanium 2SA798 dual transistors and of course, alignment. The current-limiting adjustment is quite fun. Basically you drive the amp into clipping at 4-ohms, and then set two adjustments. The amp heats up quicker than your electric stove when doing this, and you have to make this adjustment FAST. Here's what it looks like now:



See the little red Wifas below? They take the place of some crappy-sounding tantalums.



This thing had a really beat-up top cover. I've come up with a method to perfectly duplicate the original factory splatter effect, so I flipped the top cover upside down and performed the magic. Perfect!



And of course, there are the obligatory Pacific glamor shots:







This thing makes big, big power into 8 and 4-ohm loads. Sonics-wise, it's a bit lacking in the upper octave, but the flip side is that you could use this as an arc-welder when you're not listening to music, so not a bad compromise!

All photos copyright 2012 Pacific Stereo. All rights reserved, no use without prior authorization from me. If I see these photos in an eBay auction, it will be taken down faster than you can say VERO!

[Old Busted Hotness]

That's a beauty!

[Elite-ist]

Very nice PS! A Pioneer Spec 2 or Spec 4 amplifier is high on my list to add to my current system. I always wanted to have a fully racked Spec series of components.

Nando.

[Nakdoc]

Were the bias relays the Hitachi reed relays? I have stashed a few of these. That would not be fun to sub.

[Parnelly]

Any of the spec gear is really nice. What kinda power is that thing pushing? 200 a side?

[Pacific Stereo]

Originally Posted by Nakdoc

Were the bias relays the Hitachi reed relays? I have stashed a few of these. That would not be fun to sub.

Yes, those are the SPST Hitachi relays (or Hitachi-style, anyway). Yep, they are a pain to sub, as there is nothing that will just drop right in.

[Pacific Stereo]

Originally Posted by Parnelly

Any of the spec gear is really nice. What kinda power is that thing pushing? 200 a side?

250 a side at 8 ohms.

[Parnelly]

Originally Posted by Pacific Stereo

250 a side at 8 ohms.

Is it different at 4ohm?

[Pacific Stereo]

Yes, it is. But I don't know what it is. I don't typically do power measurements at 4-ohms, and I did not do it this time, either.

[Parnelly]

Originally Posted by Pacific Stereo

Yes, it is. But I don't know what it is. I don't typically do power measurements at 4-ohms, and I did not do it this time, either.

Is that simply because 4ohm is not common in household setups? Or is there another reason?

[Pacific Stereo]

It's because testing at 4-ohms is just tempting fate. I don't like stressing 35 year old products to their absolute limits unless there is a good reason to do so.