Aria Pro 2 SB1000

[Briansbrew]

Hi Guys,

All the finishing work is now complete, parts are all back on again and she is playing great.

I was worried that the batteries were draining quickly but that was down to poor quality and I have also deactivated the LED indicator which was pulsating and annoying.

Anyway what with the bad weather I wanted to take some pics outside but this has been delayed until next week so I will upload them then so you can see the end result, Im quite happy with it.

Brian 

[Prostheta]

Sounding good Bri! I know we've discussed this on and off privately, however I think this is a fascinating bit of SB-1000 lore that deserves to be discussed publicly. 

 

On 3/1/2018 at 11:02 PM, Briansbrew said:

 

The mashed splining and solid shaft are the result of the pots having been replaced. I think I mentioned that they were original earlier in the thread (or in private) however I somehow totally got myself upside-down. They're definitely *not* original.

The LED, open-book headstock, active/passive switchable circuit and several other design factors are hallmarks of the 80s basses. This is the schematic for the 80s SB-1000:

 

Although this schematic is readily-available online, the original had errors which this schematic corrects. My point though, is that the pots are dual value dual gang in the 80s SB-1000. 20k on the upper gang and 500k on the lower gang. A very unique and PITA choice which are simply not commercially available. I've swapped wafer values between small dual gang Alpha pots before however I've not found high quality larger dual gang pots that this can be done in reasonably. That sort of leaves us in a bit of a pickle.

 

The 70s SB-1000 circuit was more or less identical to "one half" of the 80s circuit. Single value 20k pots with the switch pulling the varitone in or out of the circuit instead.

 

Essentially, the 80s circuit is active full-time, with the 4PDT switch passing the pickup signal either to the 500k "passive" pot gangs, back to the switch and out to the socket - forming a very standard volume/tone configuration - or to the preamp, through the 20k "active" gangs, back to the switch and out to the socket. In my opinion, this was done to provide an unpowered backup mode should the batteries fail mid-performance. Overly-complicated and a pig to repair.

Since a previous owner ditched these irreplaceable dual value pots and substituted them with 500k pots, you're more or less left with an underperforming active circuit which doesn't provide a low impedance (low loss, noise resistant) signal to your cable run. It would seem that the 500k pots are performing double duty for both the active and passive modes in lieu of having the correct lower value pots (and higher value capacitor). If this works well enough for you then there's no real need to make massive changes. At the least, I would buy a new pair of pots and swap out the beaten-up crusty existing ones.

[Prostheta]

The original active-only 70s circuits were a lot more compact, although that 10-way header doesn't make it seem that way.

 

A point of trivia here is that the designers kept the same jigs for the control cavity between the original 70s design and 80s facelift. The LED was mashed through one of the raised central areas whereas everything else was nicely given its own specific recess. The battery arrangement was lightly altered so that the preamp could live under them rather than screwed to the back of the brass control plate.

 

The way that the dumb blinking LED circuit was wrapped in electrical tape, bonded straight to the jack socket and with the LED itself located where it was makes me suspect that it was a last minute design afterthought. Everything else in these basses was very well designed (apart from perhaps the pot choices....) otherwise.

This is a retrofit loom I made for an original 70s bass. It isn't perfect (cap size, perhaps?) but sounded sublime.

 

[Briansbrew]

Facinating stuff Carl, you mentioned that my pots may not be original but when I took the loom out I forgot to photograph it for the thread but on closer inspection (see Pic ) on the vol pot it says 500k ohms x 2 and on the tone pot its got M 500K ohms,  20k ohms have a look at the pic and see if thats the case, one pot sits on top of another for both vol and tone, still dosent explain the the different shafts though. Hopefully they are original, sound wise it is great but I do not have anything to compare it too.

I have disconnected the LED wires but I would like to take the PCB out as well, would this compromise the circuit.

Thats a neat looking loom  by the way Carl, good steady hand

 

 

 

 

 

 

 

 

  

[Prostheta]

Ah, I see. The photo you PM'ed me wasn't too clear at first. This changes things immensely.

Those pots are dual gang whereas they looked single in the original photo. The tone pot is original. That's a pot that Matsumoku used. I suspected that, however with me not thinking it was dual gang I discounted the idea before I thought anything more of it.

So this means that the circuit is (as far as we can tell) in original state other than a dual-gang 500k pot being transplanted in place of the original 500k/20k volume pot. It's not ideal, but a lot simpler to accept than a complete re-write.

[Briansbrew]

Yes carl that makes sense now that I understand the working of this loom. 500k for passive and 20K for active, would the sound be vastly different in mine compared to an all original SB100. I don't suppose there is much that can be done to improve it.

Funnily enough the grounding issue is not there today when I used a different practice amp.

All good stuff and I have learned a great deal so far about these Arias, they did say you were the Aria man, very True

More pics to come this week

B 

[Prostheta]

I wouldn't say vastly different, no. The function of the preamp is to buffer the signal from the pickup without a reference to earth. Sort of like an active DI box I guess. The best aspect is that it allows for a lower impedance signal, and the values of the pots can be lowered. It also has the added effect that cable capacitance no longer rolls off treble in the audio spectrum unlike passive mode circuits. I'm not completely sure, however I believe that this treble rolloff will occur with the circuit configured like it is. @curtisa will likely be able to take one look and say for sure. I'd have to shake my brain trying to get the answer to fall out like a pick in an acoustic soundhole.

Happy to help out. These are fantastic old birds as @Norris well knows. Amazing instruments from a slice in history.

[Briansbrew]

Well ladies and gentlemen my project is now complete and here are some pics of my beauty.

First I would like to thank Carl (Prostheta ) and Norris for their help and input to this project, it really was good of them.

I finished the bass in Try oil and the result was much better that I imagined and easier to apply than spraying. The decal was tricky for me and the only mistake I made was to get it in gold instead of black which would have stood out better but we cant all be perfect. The stain on the back was too deep to get fresh wood but that was years of playing and worn through the lacquer.

It plays fantastic and the action is great, took a while to get used to the string spacing as it is fairly parallel but goos once its mastered. 

anyway some pics guys.

 

 

[Briansbrew]

[Andyjr1515]

That is absolutely splendid, Brian.  Now and again on the forum, there are instruments I would REALLY like to own....and this is one of them.

Great recon job, @Briansbrew and fantastic Aria knowledge demonstrated once again, @Prostheta.  

Well done, both

[Prostheta]

She looks great, @Briansbrew. A credit to both Matsumoku and your dedication in peeling back 30+yrs of what looked like heavy use. I admire these basses because they are just resilient, mighty instruments. The fingerboard and fretwork looks great, and that nut is just perfect. Absolutely fantastic.

I like how your decal is actually the '70s script ("The Aria Pro II") from the batwing version. I always preferred that one myself. 

Glad to have provided what I could to fill in the gaps. As I always say, these basses are rapidly becoming a "new vintage".

[Briansbrew]

5 hours ago, Prostheta said:

She looks great, @Briansbrew. A credit to both Matsumoku and your dedication in peeling back 30+yrs of what looked like heavy use. I admire these basses because they are just resilient, mighty instruments. The fingerboard and fretwork looks great, and that nut is just perfect. Absolutely fantastic.

I like how your decal is actually the '70s script ("The Aria Pro II") from the batwing version. I always preferred that one myself. 

Glad to have provided what I could to fill in the gaps. As I always say, these basses are rapidly becoming a "new vintage".

Thanks Carl,

It was a pleasure working on this beauty, very sturdy construction and will last for many years to come, yes the fingerboard and frets came up great-years of neglect but easy to enough to bring back to life. Well pleased with the way the nut came out. All in all a great project and thanks again for your input and explanation of the electronic side of things. 

The decal was purchased from Rothko and they has this decal on their database so I like it too, pity about the Gold but hey the bass plays well and thats all that matters.

Edited March 25, 2018 by Briansbrew

[Norris]

Excellent work and great to see another Aria rescued from a bit of a state