Alembic Guitars Club
Connecting => Swap Shop and Wish Lists => For Sale & Trade => Topic started by: fivestringdan on December 01, 2024, 08:14:13 AM
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Power transformer is on the back instead of internal. I don't know who did the mods. It's all working.
$300
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Yikes! Those are some pretty heavy handed mods. Is this something that has come into your possession? How / why? If you take the feet off you can slide the internal chassis back and out of the shell. I'm curious to see if there's anything left inside the box.
Based on the non-stock isolating washers on the 1/4" jacks I'm going to guess that the original owner was chasing a hum problem? That may have led to them moving the power transformer outside of the box away from the signal path. But I'd also hazard a guess that these mods were unsuccessful in fixing the issue - which was more likely rf coming through the pickups. Not a grounding issue nor a power transformer related issue.
Nice that it works though!
Jimmy J
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Yikes! Those are some pretty heavy handed mods. Is this something that has come into your possession? How / why? If you take the feet off you can slide the internal chassis back and out of the shell. I'm curious to see if there's anything left inside the box.
Based on the non-stock isolating washers on the 1/4" jacks I'm going to guess that the original owner was chasing a hum problem? That may have led to them moving the power transformer outside of the box away from the signal path. But I'd also hazard a guess that these mods were unsuccessful in fixing the issue - which was more likely rf coming through the pickups. Not a grounding issue nor a power transformer related issue.
Nice that it works though!
Jimmy J
I got it as part of a bass deal from Brian. Yeah, it slides out. I'll take some pictures of the chassis as I'm curious as well.
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every now and then i fantasize about taking my SII and the A-bass to a gig. one problem is that my DS-5 is integrated into my home rig and i don't wanna cannabilize it to play a show. besides the fact that the case for that bass is as big as a full-size coffin (with built-in wheels), i'd hafta do the gig wearing a 14-lb robbery magnet that's worth more than most people's luxury cars. my road rig is already bi-amped, all i'd need to go stereo is a DS-5. doesn't hafta be pretty. i ain't skeeered of re-habbing one, done it a coupla times already. makes this kinda tempting. got a big audition tomorrow that actually might turn into a band. might hafta get back to ya on this.
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I received that DS5 as part of the ridiculous deal I got from a musician from Canada for a well worn defretted series I. Never used it as Ive got a rack version as well as a backup so threw it in as part of my Europa 6 string deal with Dan. I don’t know why the mods were made but a little tweaking with the hum cancelling adjustments with the Series I took care of a slight hum I originally noted. I’ve subsequently played it in a number of venues without any problems. Then again, he was a touring pro who played in a lot more places than I do.
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I wouldn't be surprised if you found one or two isolating audio transformers inside the box... Let us know!
Chasing hum or audio noise can be challenging. Ground loops for example can be elusive. And it's always been tricky with our big single-coil Series pickups which can hear all spurious e-noise. Before the individualized mods that Ron W came up with the noise problem could be somewhat frustrating, especially at certain venues or in environments with lots of other equipment - like almost everywhere.
In my early days with Alembics I recognized the occasional hum issue as just a part of why the bass sounded so great. So I found ways to deal with it along the way. Like spinning around until I found the position with the least noise and standing that way, even if it meant pointing the headstock towards the audience. HA! After Ron did the upgrades on my basses I have rarely ever had to think about it. Genius.
Jimmy J
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Inside pictures
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Well heck, no transformers. Bad guess.
That looks like the stock bridge rectifier and regulating caps but there are a few extra components I don't recognize. They've gone to a lot of effort to add a ground-pin to the AC plug and cable, a standard fuse post, and then isolating the 1/4" jacks from the chassis and adding a "ground lift" - although I'm not sure how that would apply.
There's certainly more space in there than in the original DS-5! It's a curious piece. As long as it's putting out a good steady +/- 15-18VDC then it's doing its job. I might not want to use it in the rain... :)
Jimmy J
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Well heck, no transformers. Bad guess.
That looks like the stock bridge rectifier and regulating caps but there are a few extra components I don't recognize. They've gone to a lot of effort to add a ground-pin to the AC plug and cable, a standard fuse post, and then isolating the 1/4" jacks from the chassis and adding a "ground lift" - although I'm not sure how that would apply.
There's certainly more space in there than in the original DS-5! It's a curious piece. As long as it's putting out a good steady +/- 15-18VDC then it's doing its job. I might not want to use it in the rain... :)
Jimmy J
Thank you, Jimmy. It was a mystery to Brian and I.
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PM sentt
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You know, the more I look at this, I think it's a heavily modded Fernandes PS-5 Power Supply. I looked for a reference photo, and while the Fernandes name isn't legible, I can see the hint of the angular lettering above the switch.
I showed these pictures to dad, and he said that this isn't an Alembic power supply from the innards. I think dela217 has said the Fernandes power supplies work with Alembic instruments. I've never tested it, but I would take his good word for it.
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You know, the more I look at this, I think it's a heavily modded Fernandes PS-5 Power Supply. I looked for a reference photo, and while the Fernandes name isn't legible, I can see the hint of the angular lettering above the switch.
I showed these pictures to dad, and he said that this isn't an Alembic power supply from the innards. I think dela217 has said the Fernandes power supplies work with Alembic instruments. I've never tested it, but I would take his good word for it.
Excellent, Mica! That's even better news as the mystery has been solved to the origin of this unit.
Please take this post down as I cannot sell it as an Alembic DS-5.
In hindsight it may have been better to ask about the unit before posting for sale but I didn't question it not being an Alembic because of the blue box color..lol
http://alembic.com/club/messages/411/208014.html?1408682942
http://alembic.com/club/messages/395/52811.html?1215240754
Found a picture of the partial inside of the ps-5
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I'll just rename it for now. Hey, I didn't even think of the Fernandes possibility until I looked at it hard.
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Stock Fernandes might be a +- 9volt power supply as they used different chips and stuff in the instruments.
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Worth using a volt meter to figure out what that PSU is spitting out. That said, although not optimal, our Series instruments can operate on +/-9VDC as they do with the onboard batteries...
Jimmy J
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Which pins would I put on the voltage meter?
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Pin-5 should be negative, pin-4 should be positive, pin-1 is zero.
So with the meter's black lead to pin-5 and red lead to pin-1 you will get 1/2 the story: is it 9VDC or to 15-20VDC?
Black lead to pin-1 and red lead to pin-4 should show the same result.
If you check pin-4+ to pin-5- you will see the "full swing" which could be anything from 18V (2x9) to something like 30-40VDC (2x15-20).
Now you're probably more confused. ;D
Jimmy J
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I am super curious to know too! I own 2 of the Fernandes "Alembic copy" instruments (bass and guitar), but neither one of them still had the original PS-5. I've measured the voltages on my Alembic DS-5s, but it seems likely that the PS-5 should have at least a slightly lower voltage due to the IC opamps they used in the instruments - as gtrguy pointed out. But truth is, they can handle almost as much voltage as the opamps Alembic uses (quite a bit more than +/-9V), so I'd love to know what voltage Fernandes actually designed the PS-5 for.
Thanks Jimmy for the guidance!
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Pretty sure Fernandes is +- 9 volts. Fernandes Alembic copies can work with an Alembic power supply, but I think it puts extra stress on the chips.
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A while back I bought an older DS-5 that was factory wired for 220v. The seller had assumed that just putting an adapter on the plug would make it work fine in the US (which of course would actually have it proving half of the intended output). He said he had been using it with a Fernandes with no problems at that level (~8-10v?).
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Yes, most voltages BELOW the instrument's maximum limit will work fine, but it will limit the headroom - i.e. how much volume it will output before it starts distorting.
And even though running a 220V DS-5 on 120V power seems like it may be a problem, remember that tons of active basses and guitars only use one 9V battery (e.g. Stingray basses), and I don't think I've ever heard of anyone complaining that their Stingray doesn't put out enough volume! By comparison, I measured my Alembic DS-5 power supply at 42.1V, more than 8x as much voltage. So even if this is running at something like ~23V, that should still be PLENTY of headroom / volume.
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15.1v was the reading on my meter
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Is that the "full swing" or only half? Pin-4(+) to ground(-) ... or pin-4(+) to pin5(-)? I'm gonna guess it's trying to be +/-15VDC for a 30V swing. And that's good power for running an Alembic as long as it's smooth and well regulated juice. Still wild to see that external transformer. All gear has a story...
Thanks for the report.
Jimmy J
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Is that the "full swing" or only half? Pin-4(+) to ground(-) ... or pin-4(+) to pin5(-)? I'm gonna guess it's trying to be +/-15VDC for a 30V swing. And that's good power for running an Alembic as long as it's smooth and well regulated juice. Still wild to see that external transformer. All gear has a story...
Thanks for the report.
Jimmy J
That's pin one and five. Anything else is really above my pay grade.
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Alright! Pin-1 is ground and pin-5 is the negative voltage, -15VDC in this case. So now we know that it's a +/- 15VDC power supply which should be nicely compatible with our Series instruments. Good work on the testing!
Jimmy J
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come to poppa 🗿
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Sold.
Thank you all for the help with this unit.
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Great to know! Thanks Dan, and Jimmy! Cheers
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ok so here's hopefully the end of this little adventure. this showed up at CastleBeenDown yesterday after i got home from rehearsal. took it out to the shop, opened it up, checked the mains wiring and verified the socket pinout and voltages per an alembic DS-5 schmatic. other than putting an inside strain relief on hte power cord i really didn't have to do anything else to it. i'll probably install a better power cord down the road i dunno.
since this was supposidly a working unit before i got it, i could've probably saved myself the shop time and just swapped it out with my current DS-5. however, i take nothing for granted with used equipment, especially if i'm gonna hook it up to the ebony amazon. fired it up, it's dead quiet just like its mate. it's got a ground lift switch, i put it in the grounded position. shouldn't have to deal with that unless ya got a gound loop issue anyways which i don't.
i haven't decided which one stays home and which one goes with the road rig yet. here they are side-by-side. there's not really many ways to do +/- 15 volts.
looks like the ebony amazon is gonna leave the woodshed with me next week and go up infront of a live band in full stereo goodness. not really sure if it's ever been played live, we're gonna make some eyes bug out whilst saturating ears with an SII strung with fresh rotos played at high volume in full stereo. gonna be a blast, methinks
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Awesome, Tim!