Peavey Pacer Tube Amp Conversion Project, Part 1

Recently I bought an old funky Peavey Pacer from someone who had it on craigslist. Even though the seller was asking less than a couple Jacksons for it, and re-posted it every couple days, it was still unsold after a month. That's not surprising, since there were only two rather claustrophobic looking photos in the listing:

I replied to the ad after noticing something almost hidden at the bottom of the second pic - the speaker was a Carvin branded "British Series", made by Eminence and known to be an excellent guitar amp speaker. At the asking price for the entire amp, I figured it was worth it if the speaker alone was in good shape. On the phone, the seller said the price was negotiable since the Pacer had some "issues" - it would shut down after a couple minutes of playing, but might stay on long enough to check it out. Well, why not - it was only about three blocks away, so I grabbed a guitar and walked over.

Although solid state, Pacers have a solid rep for decent tone, as well as being really loud, and that's the way this one was. Right away it was obvious that the Eminence speaker was in good shape; I turned the Pacer up to ear bleeding levels (60+ watts!), and the Brit Series didn't flinch. As predicted, the amp's volume soon dropped to less than 1/4 what it had been, but okay, I'm sold. I handed over some cash and took it home.

The picture at the top of this blog post shows the Pacer as it was at that point, and here's a couple more:

 Here's the speaker:

Yup, that's an Eminence, and also yup, that's a boo-boo on the cone, repaired with a bit of black goo. Luckily, the hole in the cone, and the goo, don't affect the sound of the speaker at all. However, it took quite a while to clean the Brit up, in fact, the whole amp was pretty cruddy.

As a double check, the Pacer's amp was bypassed, and the Carvin British hooked directly up to a known good tube amp here, and it sounded very very good - efficient, balanced across the tonal spectrum of an electric guitar, able to handle a lot of power without becoming overly compressed, yet with just the right amount of breakup at higher volume or on dynamic peaks when you're really digging into the strings - nice.

And why is the speaker called a "British Series"? Good question; maybe Carvin was trying to capitalize on the tonal reputation that the older English made Celestions had. But this doesn't sound anything like a Celestion, but rather, just like what it is - one of the better models from Eminence, and in many ways superior for most styles of music than any Celestion. If I had to compare it to any other speaker I've ever played through, the Carvin Brit's tone and efficiency is very similar to that of a late '60s Jensen C12N.

I wasn't going to repair the Pacer; just happy to get a nice toneful speaker, which I was planning to put into a Leslie cabinet. However, the speaker output plug looked a bit suspicious:

I should have taken a photo of the inside of that plug - it was a mess, and the resistance between the plug tip and the the other end of the wire was over 120 ohms. Whoa - maybe that might have something to do with this Pacer's "issues", as the seller called it. I clipped the plug off, and soldered on a new old stock Switchcraft right angle plug:

Turned it on, plugged in a guitar, and torture tested the amp for over a half hour - no problemo. The repair, if you can call it that, only took ten minutes; so cool, now I have a usable amp for not very much bucks, even if it doesn't have any tubes.

My hypothesis is (could be wrong, I'm not a transistor amp repairman) that the incredibly high load on the pair of output devices, 1,500% of rated value, caused them to run so hot that the thermal sensor on the chassis, located between the two big TO-3 sized transistors, went into protect mode, and lowered the circuit voltages enough to save everything from going up in smoke. When the transistors cooled down after shutting the amp off, the sensor would allow the amplifier to run at full power again, until it overheated and go into fail safe mode once more. The Pacer's designers knew what they were doing, and that's great.

Here's a picture of the innards - note the thermal sensor sitting between the two output devices, which use the amp chassis as a heat sink:

As long as I had the amp torn apart, I cleaned it up as well as possible, got a new plug for the AC cable, and since one of the control knobs was missing, a set of old-school radio knobs were put on:

That amp was filthy, but now it's all cleaned up and ready to take to a jam, which I did. I thought the Pacer sounded okay enough for a $20 amp, but wow - I sure wasn't prepared for all the rave reviews it got. Here's a couple examples: "Your new amp sounds horrible!" "That's the loudest piece of sh*t I ever heard!", and my favorite: "I never thought I'd say this, but suddenly your tone really sucks!"

Well okay, the people have spoken. But the Pacer isn't really a crappy amp, it's just me not knowing how to use it. I've played exclusively through tube amplifiers for so long, maybe I've become overly dependent on the natural compression and singing sustain that comes with glowing hot vacuum bottles in a cranked tube amp. But whatever, they were right: suddenly, my tone really did suck.

As a reality check, over the next week I played through the Pacer at home for hours, and it sounded not great but good enough. The problem was that in a band situation, I didn't sound good playing through it. At the next jam, I used a Fender Blues Junior, and all was good again. Oh well, I ended up with a great sounding speaker, and that's why I bought the amp in the first place.

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A friend, David in Mass, hipped me onto the fact that some of the Peavey amps of this vintage had finger or dovetail jointed solid pine cabinets, and suggested I take a look at the Pacer's cab. Sure enough, it's a quality made, lightweight pine cab, although the baffle is a heavy piece of low-grade particle junk board. As a bonus, the amp chassis seems very suitable for a tube amp conversion build, so my course was clear: I decided to turn the Pacer into a home brew tube amplifier.

After a tear down, all of the Pacer's components besides the baffle, cabinet, and chassis, were sold on eBay for what the buyer, a Peavey aficionado and experienced repair guy, considered a fair and low price for a working circuit board and misc useful parts:

Minus listing and sales fees, and PayPal's transaction charge, I was able to net a bit more than what I'd paid for the amp, and the aluminum trimmed baffle board was given to a neighbor who thought it would look cool as a decoration in his music room:

At this point, I've ended up with a fine sounding speaker, as well as a usable amp chassis and a well made combo cab (minus baffle), for a total cash outlay of less than zero. My kind of no buck/low buck project, for sure.

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In Part 2 of the Peavey Pacer Tube Amp Conversion Project, we'll make a new baffle from a piece of 60+ year old solid core plywood, and start laying out the chassis for a tube amp conversion. In the meantime, here's a photo in process:


Unknown said...

Very cool! I just got one of these from a friend of mine. Not terrible sounding, but not great. I as also thinking of doing a tube amp conversion. Looking forward to seeing how this turns out!

Unknown said...

Very cool! A friend of mine gave me one of these amps not too long ago. It sounds OK. I as also thinking about converting it to a tube amp. Looking forward to seeing more on this!

James Aoyama said...

Hi -
Thanks for getting in touch! I kind of forgot that Peavey Pacer project - way too many other projects and home fix-its came along since, and I need to finish this one for sure. So thanks again for the reminder, and more details are coming soon.


John1948 said...

Mr. Aoyama: I have an old Pacer from about 1980 and it sat in my closet since 2005. Recently I took it out, replaced the A/C cord, replaced all the aluminum capacitors, upgrading the 1000uF caps to 2200uF, cleaned all the pots and cranked it up. Haven't played in years, so tone is not the amp's problem. Still need to replace the "Volume" pot although it is working. It seems to have a few dead spots that won't go away no matter how much "Deoxit" I squirt in there. Almost everything else seems fine except: 1.Power lamp is intermittent and I haven't figured out how to get it out of the holder yet. 2. I would like more "Reverb" level. It is clear but not quite enough. Maybe reducing the 10k input and output line resistors?

The tone controls used to have little effect, but now they are working perfectly since cleaning everything up. Sorry you're so down on solid state. This is the only amp I have ever worked on that uses a xformer to drive the outputs. Also the only amp I have that uses a glass circuit board where everyone else at this level used the old phenolic boards that burn up when you try to solder in new parts. Maybe I'll start playing again!

Unknown said...

The Peavus Pacer is one of the best dirt box / modeler driven amps ever made. I have been using them for decades and have not had anyone say it doesn't sound really good. I did seal the backs and put in EVM12 speakers in the 2 that I have. Giant improvement, not for distortion ,but for power handling and crystal clear sound reproduction . I use 2 Pacers driven with a Zoom 606 pedal (believe it or not) and I also run a Peavey ULTRA 112, all at the same time. The Pacers are set for low input volume and all eq's on or close to 10, and the master on 10 .It is basically run like a power amp. It is a great distortion box amp ,the best I have ever used.

James Aoyama said...

Hi Mr Unknown -
Thanks for reading some of the blogpost, also thanks for getting in touch! Wow, sounds like an insane and killer party rig - a Zoom pedal through a wall of Pacers with all knobs on 10... what could possibly go wrong?

Well, keep on rockin' the free world!


James Aoyama said...

Reply to John1948:

Hi John! Thanks for taking the time to read the blog. Sounds like you know how to work on solid state gear, especially Peavey stuff - I'm dumb, just know tube amps. I'll comment on a couple of your points:
- Keep squirting Deoxit will solve one problem - the pot will dissolve inside and a brand new replacement will sound great.
- Pretty sure the Pacer power-on lamp doesn't have a replaceable bulb; has to be replaced as a unit.
- Easiest way to get more (and better sounding) reverb is with a pedal. Highly recommend a Boss FDR-1.
- I'm not "down on solid state" - as mentioned in the post, a tube 1st gain stage is a musical crutch for me. Wasted my youth partying and constantly gigging, never really learned how to play.
- Yeah, older Peavey amps are made almost 100% bomb proof.
- Getting back into rocking out is a great thing - go for it!


Anonymous said...

this is a cool write up, but i can’t believe that you found the tone unacceptable! these amps sounds absolutely wonderful, and i’m really surprised that they have not caught on. the stock speaker (which yours did not have) is somewhat of a crucial component, which is something that will surely get overlooked by the uninitiated. i think the peavey badge will (unfortunately) cause some folks to pass judgement prematurely.

James Aoyama said...

Hi Anonymous -
Thanks for reading some of this blog post! Re acceptable tone, a really good player can make almost any amp sound good, even a Peavey transistor rig; as for me, I need the dynamic boost of hot glowing vacuum bottles to get me through the song.

As mentioned numerous times, I never actually knew how to play guitar. Although I was able to get well paying gigs constantly when I was younger (due to a fortuitous combination of youthful chick-magnet good looks and a snazzy wardrobe, pro attitude and confident stage presence, knowing how to make approximately appropriate instrumental noises in almost any genre, having a sizable arsenal of cool vintage gear, and an ability to sing stacked vocal harmonies in all ranges) I never really acquired enough musical technique to be able to make an amp like a Pacer sound good.

Also, guess what? The Peavey Pacers did "catch on"; they sold tons of them in the '70s. And as for the stock speaker you describe, which I assume are the Scorpion line, even they have their fan boys - presumably the same folks who enjoy eating poisonous puffer fish and drinking 190 proof Everclear straight.

And finally, as for the Peavey badge, I hear that the version made of metal can be used as a fine offensive weapon, either wielded like a switchblade or precision thrown. I wouldn't dream of "passing judgement prematurely", or anything else prematurely for that matter.