Jersey Girl

[littlesongs]

An Ampeg Echo-Jet arrived at the homestead just the other day. Thankfully, most of the news is good. Ugly as it looked in the auction pictures and sounded in the description, the amp hasn't been messed with all that much. The original footswitch, jumpers and reverb tank are all intact. The transformers and most components are just as they were in Linden. It even has the original Ampeg labeled 5Y3.

Because of the dicey ungrounded power cord, it hasn't been played a whole bunch. I haven't jumpered the Ampeg to the Sano to test the superdupergroovy outboard reverb feature either. Still, in no-frills Jet mode, it has a full, smooth and shimmery tone that defies the size of the cabinet. Although it is not a well-known nor celebrated tube, I think the 6D10 preamp sounds just fine feeding those 7591s. All Compactrons are long out of production, but thankfully this one can still be found. If I've read the date code right, the first owner blew up the original speaker and had it replaced with a Jensen Vibranto at some point in 1967. Aside from a bit of hum and a dirty tone pot, this amp sounds good. Plugging in a Guild might have had something to do with it too. :0)

Echo Jets debuted in 1963 as one of the first two Ampeg designs to use 7591 output tubes. From what I've gathered, this particular model of Echo Jet was only made for a handful of months. It is an EJ-12-A and the serial number seems to indicate it was the 16th amplifier completed in July of 1965. A little later in the year, the amp was redesigned again as the EJ-12-D. By 1966, the Echo Jet was gone. Although it is gonna take some time and work to get it into shape, I'm happy to have found this rare old bird.

 

[kakerlak]

Neat amp, makes me want to spend the time/dollars to fix my dead R-12 Rocket.

What do you think the sound of the 6C10 7591 combo is like compared to the 6SL7/7591 (other than yours has reverb and mine doesn't)?

 

[littlesongs]

Neat amp, makes me want to spend the time/dollars to fix my dead R-12 Rocket.

What do you think the sound of the 6C10 7591 combo is like compared to the 6SL7/7591 (other than yours has reverb and mine doesn't)?

I don't have first hand experience to compare the two preamp tube combinations. From what I have read and heard, the pre-Compactron designs are much more sought after and have a more traditional sound. These later Jets are not particularly celebrated, the sound is derided as too clean and the lack of new preamp tubes makes them shunned by many. Still, my limited experience tells me that they are worthy of consideration. As a standalone Jet, this is a nice warm and clean amplifier at moderate volumes and the grit factor seems fairly low. There is delicious harmonic stuff going on that is consistent at even the quietest setting, but it is not really a rock sound. It fits what I am trying to do quite well, though it might not be every player's cuppa tea. I did not crank it wide open, but it probably has a primal scream in there somewhere.

Those Rockets are really cool amps. Got some pics? I think you should get it going again. It wouldn't hurt to discuss another Ampeg restoration at LTG, would it?

 

[Ian]

OOh that's topical. I just finished reading Peter Guralnicks book about Elvis Presley, and there's a story in there where Scotty Moore and Chet Atkins are discussing Echo Jet amplifiers As an aside, I think 7591a's are now back in production somewhere aren't they (capn ?)

Looks a beauty anyway, I'd love to give that a good thrashing !!!

Cheers, Ian

 

[littlesongs]

OOh that's topical. I just finished reading Peter Guralnicks book about Elvis Presley, and there's a story in there where Scotty Moore and Chet Atkins are discussing Echo Jet amplifiers As an aside, I think 7591a's are now back in production somewhere aren't they (capn ?)

Looks a beauty anyway, I'd love to give that a good thrashing !!!

Cheers, Ian

Ian, thanks for the tip on the book! I'll have to check that out. Yes, I believe the 7591 is back in production overseas. On the other hand, the 6D10 has not been produced since the early 80s.

To confirm what many may suspect already, Cap'n Juan is helping me a great deal to get this project on the right path. Thanks John!

 

[Ian]

Tube Depot has 6C10 in stock, not cheap at $34.95 each though. I'll keep a look out for you locally...

Triple triode's must be a bit of a rarity, cant think of anything Hifi that I've ever seen them in, that would also infer that there won't be an easy substitute ?i

 

[Default]

6c10 $29.99 @ Tubesandmore.com

Probably can find them cheaper elsewhere if you scratch around. Compactrons where made for tvs and the supply is pretty good, because nobody rebuilds old tv's in numbers. :wink:

 

[Jeff Haddad]

Nice amp, looks real clean. I've always liked the blue check covering on those era Ampegs. The only Ampeg I have anymore is a GU12 - it's black vinyl. The Echo Jet plugs into or clips onto another amp to provide the "echo" function, correct? Should sound good with the Sano, they're probably cousins anyway...

If you know of any old-time TV/Radio shops, they sometimes have old tubes - you might score a spare 6C10. I did that 10 or 12 years ago when I first got my Reverborocket to find some 6SL7's. And I have just recently found some NOS 12ax7's and others at another old shop. Even found some Amperex 12at7's with perfect lettering and boxes. I'm planning on taking some pix of these to post in a new thread sometime. I may make another trip there in a few weeks and I'll check for the 6c10.

 

[Roger Smith]

Cool !

 

[kakerlak]

Those Rockets are really cool amps. Got some pics? I think you should get it going again. It wouldn't hurt to discuss another Ampeg restoration at LTG, would it?

Just this one:

And lots of inside shots on this old thread

What's a "compactron?"

 

[littlesongs]

OOh that's topical. I just finished reading Peter Guralnick's book about Elvis Presley, and there's a story in there where Scotty Moore and Chet Atkins are discussing Echosonic amplifiers

Echosonic amplifiers were custom built by Ray Butts and used by Scotty, Chet and Luther on some huge recordings. Deke is probably the only well-known contemporary guy with one in his arsenal.

My amp is cool, but not that cool! 8)

Ian, Steve and Jeff, thanks for offering to keep an eye out for me. These amps aren't very hard on their valves, but a few cheap spares would be nice to find for the long run.

 

[littlesongs]

And lots of inside shots on this old thread

What's a "compactron?"

Thanks for the pic. Your ol' Rocket is a beauty! The vintage guitars and the tombstone radio are mighty nice too.

I'm sure other folks know far more than I do, but my understanding is that Compactrons were a reaction by GE engineers to the rise of the transistor.

Here is a very cool site about Compactron tubes.

 

[littlesongs]

Nice amp, looks real clean. I've always liked the blue check covering on those era Ampegs. The only Ampeg I have anymore is a GU12 - it's black vinyl. The Echo Jet plugs into or clips onto another amp to provide the "echo" function, correct? Should sound good with the Sano, they're probably cousins anyway...

Thanks Jeff. Yes, that's exactly what it does. This Youtube demo and this soundfile from a local fellow sums it up pretty well.

The "cousins" comment might not be that far from the mark. The guitars and amps were all born in Hoboken, Irvington and Linden within a three year period. If they were people, my gear might have known each other growing up.

 

[Ian]

Thanks for the link about compactron tubes: a picture is worth a thousand words: They are short fat little suckers with 12 pin bases right ? I did used to have an amp that ran one , it was a VTL 40 watt integrated... Dont know if it was a 6C10, but it was one of those....

I'll keep my eye's open for you.

Cheers, Ian

 

[littlesongs]

Thanks for the link about compactron tubes: a picture is worth a thousand words: They are short fat little suckers with 12 pin bases right ? I did used to have an amp that ran one , it was a VTL 40 watt integrated... Dont know if it was a 6C10, but it was one of those....

I'll keep my eye's open for you.

Cheers, Ian

Thanks Ian. Yes, they are stubby and stout like a 12 legged bulldog. By the way, I really screwed up this thread, so don't feel bad for confusing Echo-named amps. It was a whole lot of fun reading more about 'em!

My apologies to everyone.

I goofed up the name of the preamp tube. The Compactron valve in the Echo Jet is a 6D10 and I've edited my previous posts to reflect the correction. My confusementalism came from the 6BK11/6C10 preamp tubes in the Jet J-12-A and J-12-D during the same era. So, while a 6C10 would be handy if I found a Jet to pair with this one, the tube I may need as a spare someday is a 6D10.

 

[Default]

Thanks for the link about compactron tubes: a picture is worth a thousand words: They are short fat little suckers with 12 pin bases right ? I did used to have an amp that ran one , it was a VTL 40 watt integrated... Dont know if it was a 6C10, but it was one of those....

I'll keep my eye's open for you.

Cheers, Ian

Thanks Ian. Yes, they are stubby and stout like a 12 legged bulldog. By the way, I really screwed up this thread, so don't feel bad for confusing Echo-named amps. It was a whole lot of fun reading more about 'em!

My apologies to everyone.

I goofed up the name of the preamp tube. The Compactron valve in the Echo Jet is a 6D10 and I've edited my previous posts to reflect the correction. My confusementalism came from the 6BK11/6C10 preamp tubes in the Jet J-12-A and J-12-D during the same era. So, while a 6C10 would be handy if I found a Jet to pair with this one, the tube I may need as a spare someday is a 6D10.

10-12 bucks at the tube retailers!

 

[capnjuan]

Hi Dave; first things first ... have to salute Guild. It made the RC20 Remote reverb/tremolo unit sometime in the early 60s (Hans or Kurt for dates). As Jeff pointed out about the EJ, it too relies on a dry signal from another amp tapping its signal at its speaker. Gibson produced the GA1RT which is functionally identical. Anyway, I had one of these that was " ... mine for a time, but the feeling wasn't divine ..."; it hummed like a sewing machine and thumped like a rabbit. 12AX7, 6BM8, and diode rectifier ... shown here in its (tainted) glory:

Signal: shown below the reverb input and tank with parallel resistor/capacitor to damp the inbound signal to something the tank could handle. The reverb out in magenta. J1, the normal guitar input and the reverb out meet and feed stage one of the triple-triode 6C10 (not sure just now what it is). The signal is coupled to stage 2 (dotted line for tone included for confusion) and appears at pin 9/grid of stage 2.

The signal heads to pin 11 - the grid of stage 3 ... amplifying stage and phase inverter from where it goes to the 7591s each getting its half of the AC waveform. I'm not completely sure about J2, the auxiliary input ... possibly a mic for yodeling; and I don't understand the function of the shorting arm there but so far, I don't have too.

The power in the amp shown below; in the lower right-center, all the taps on the transformer; red for high voltage secondary AC, yellow for 5VAC heaters for the 5Y3 rectifier, and green for the 6.3VAC 7591 and 6C(?)10 heaters. Shown far left the current filter caps and dropping resistors.

The primary DC (red) goes to the center tap of the output transformer and winds up on the plates / anodes of the 7591s. The magenta is power for the twin screens (pins 4 and 8 ) which are jumpered together. The blue is the power to three sections of the 6C(?)10.

The power supply with all the transfomer taps ID'd and the three filter caps on the left (more on filter caps below). Note the 'yellow' cap that doesn't match the others and how its red lead touches the already-scorched power resistor:

Whoever put that yellow cap in didn't bother to straighten the mess out - see left below. On the right are listed all the pieces and parts that connect to pin 8 of the rectifier and on the left, how tidy and neat the work appears:

Edit: my screw-up. No high voltage AC on pin 8: should read:

The pin marked A is unused by the tube but Ampeg used it as a convenience tie point for one leg (white) of the incoming 110V service, a black wire leading down and away to the 'death cap' (the lead is sleeved), and the black wire (right center) marked '105' that feeds one side of the transformer. Whoever put the 'yellow' cap in by laying the new (red) capacitor wire on top of the high voltage DC (+/- 325 volts) coming out of the rectifier, left it within a gnat's a__ of the incoming 110VAC :shock: :twisted: :shock: Slosh some water/wine/beer/Stoly in there or get a whopper spike and an arc ... not good.

It needs a new 3-wire cord but it also needs new caps sooner rather than later. Had this condition at pin 8 been cleaner and unless it was humming to beat the band, the caps could have waited. More on (moron?) caps; Dave says the on-amp schematic indicates 40uf/20uf/20uf ... hmm ... the RCA tube data sheets for the 5Y3 indicate not more than 20uf at the input of the filter ... that would be the first filter section ... wondering ... if it was originally supposed to be a 5U4 and not a 5Y3 ... although the same schematic indicates a 5Y3 :?

The public domain / Joe Piazza schematic, shown above, shows 20uf/20uf/20uf which is consistent with most 5Y3-driven designs. Anyway, I'm proposing something like this; a small rack made of two wiring strips; upper center is the ground side, upper right the hot side. The two dropping resistors; 1K/10W and 22K/1W can be mounted between the lugs on the hot side with leads already in place when the unit is dropped in .. one .. maybe two holes drilled in the chassis:

One way or the other, the condition at the rectifier socket has to get cleaned up.

The Compactrons: 6U10, 6C10, 6D10 and others ... they are triple-triodes; three different stages inside one bottle. They vary mostly by their arrangement of low, medium, and high mu / amplification factor; medium-medium-high or high-high-medium for examples depending on what each stage is being asked to do. Their biggest virtue is you can get three stages into one tube socket and reduce draw on the 6.3VAC heater supply. More on Compactrons Here.

Lunchtime.

Edit: fixed text re/ connections at rectifier.

 

[Jeff Haddad]

Wow cap'n, my posts feel so inadequate after reading yours!

I just checked the GU12 schematic and I'd better get back to that shop - it takes a 6U10 and 12DW7!

 

[capnjuan]

Thanks Jeff: I used to make my own 3' X 4' courtroom exhibits and PowerPoint slide shows to explain and support my testimony ... scintillating stuff ... construction delays on water treatment plants, condos, rock claims on road and drainage projects ... real snoozers for most people but professional mother's milk to me Re/ the 6_10 tube family, the 12DW7, and your GU12; a clip from your schematic illustrating the importance of varying amplification factors in each tube section.

The signal is coming from the left and hits the first section of the 6U10; note its voltage is a modest 76.5 volts. The signal continues to the green diamond where it splits; following the magenta line, it enters stage 2 with its 10K (not much resistance) 2W (high heat dissipation) resistor and noticeably higher 225 volts that ramps the signal strength up to drive it through the 'C' unit (Ampeg-speak for reverb can). Stage 3, the reverb return; its voltage all the way back down to 94 volts to keep the reverb signal from losing its lushness. The dotted line goes to the footswitch which grounds the signal out for 'off'.

The black line is the dry signal bypassing the reverb section; it goes around and is met by the wet signal at the input of the 12DW7 where both are amplified and mixed in a tube section that's built like a 12AX7 which has a high - 100 - amplification factor. The dry signal (or mixed if the reverb is on) goes to the driver half which is built like a 12AU7; having a lower amplification factor of 17 but a higher tolerance for voltage. Notice in the blue box the small - compared to the others - resistor value of 15K and the resulting comparatively higher 205 volts.

Wassallat mean Juan? The differences in the 6_10 family have mostly to do with how much voltage each section can handle and their amplification factors; it's not about tone, it's about function. The higher voltages appear where a section is intended to do heavy-duty service ... handle more voltage/heat/stress.

With the introduction of Guild's Thunderbass head series and all the higher-powered heads and combos that followed; Quantum, BigBird, ThunderWhopper ... all of the them used the 12DW7 (a/k/a 7247) as the final gain/driver/phase inverter tube; practically bullet-proof. If you have a buck or two floating around, you might look for a Brimar or other up-scale brand; it'll sound great and last forever.

 

[Jeff Haddad]

Thanks Juan, I'll have to bookmark this topic so that when I retrieve my GU12 from the closet, I know whats going on. (After I re-read it a few more times!)