sandy_r

As a 'halfway-house' solution between my JFET preamp (2 channel; full VT control; 2mA drain; no headphone out) and the Aria preamp + cap fix (1 channel; V + Treble-cut; 11mA drain, headphone out), i've drawn up and tested a circuit based on the Aria components (2 channel, V + Treble-cut; 4mA drain, headphone out) It keeps some aspects of the original intent by Aria, but hopefully improves some of the issues: it uses the same IC chip, LM386, which has low distortion and noise levels and can drive headphone output; it uses exactly the same electret biasing and Tone components, so the source sound is unchanged; the current consumption has been reduced to 50% of the original circuit, doubling the battery life; using a standard guitar/instrument jack cable (ie. mono) now keeps the signals from both electret mics in the bridge, instead of only one; the electrolytic capacitors (which dry out with time and have caused a variety of unmusical effects) have been replaced with either tantalum capacitors (much longer life and reliability at these low-power levels) or good quality non-polarised capacitors, where more appropriate; the headphone output feeds the stereo ¼" jack (as a mono signal, now, ie. same to both ears, rather than one mic signal to each ear) The signals from the 2 electret mics are mixed equally into 1 channel now, using a pair of 47k ohm fixed resistors (these could be replaced by a single 100k trim pot, which would enable the balance between the 2 mic outputs to be adjusted/preset) Since the circuit uses an LM386 IC in standard configuration, the core part of the circuit can be built using a generally-available PCB/kit for DIY construction, populated with the components shown here. The remainder of the circuit just adds the passive components for the electret biasing, the dual Tone control, and the outputs to the dual Volume control (a total of 6 fixed resistors, 4 capacitors and 2 dual 1k ohm potentiometers) [photo of new DIY Sinso LM386 board] Suitable LM386 kits can be found from all the usual suspects: for the prototype, I used one of the PCBs available for the Ruby Amp (chosen for its small size), but there are many general-purpose LM386-based audio kits which would be suitable [1x LM386 pre, Tflat] NewSinsoPCB-fingertip.mp3 On my schematic for this new board I show an optional fixed-gain addition, between pins 1 & 8 - the original Aria board didn't use it, and I haven't found it necessary. If wanted, the default gain can be increased from the standard 20x anywhere up to 200x. The LM386 datasheet contains the details (be advised, though, that increasing the gain will increase the noise floor, it could seriously overload your amp input, and adversely affect the battery life - you may also find that you need to 'customise' the kit PCB to accommodate both of these 2 extra-gain components)

Since then I've joined BC and found more reports of Sinsonido control woes, both here and at SoundOnSound (an excellent account by @Richard R of a team effort in 2018 to fix a Sinsonido with the control issue) The SoS thread produced the first look at the Sinsonido PCB circuit, with all its weirdness - the control issues appeared to be due to a combination of aging electrolytic capacitors and non-standard design with additional filter components i bought some used Sinsonido parts and tested the PCB in my own Aria bass - the Tone control had no effect, and the output was very low i've re-created in part the SoS fix on that old Aria board, and i've also removed un-necessary components - the Aria PCB + fix is now operating acceptably (to the spec presumably intended by Aria): Volume is working correctly; Tone is working as a conventional 'Treble-cut' type control, as used in passive guitar controls; battery drain is slightly over 10mA; if you use a standard instrument jack-lead, as suggested by Aria, then you'll lose 1 channel from the 2 mic. pickup in the bridge (so the output will either favour the E string or the G). You would need a stereo-to-mono adaptor cable to produce a combined mix of the 2-channel output [Aria PCB schematic by W.G., from SoS thread - annotated here for this fix] (Tone electrolytic caps replaced with multilayer ceramics; un-necessary caps removed - all others replaced with Tantalum bead electrolytics) [Aria PCB fix, Tflat, 2 channel mixed] SR-Sinso-Old-PCB-fix-Tflat-2chan.mp3 [Aria PCB fix, max treble-cut, 2 channel mixed] SR-Sinso-Old-PCB-fix-Tbass-2chan.mp3

Around 2009, having got a blues/rock band together, i bought a second-hand fretted Aria Sinsonido bass and started to use it exclusively as my gigging instrument - great tone, easy action and soooo light! ...just one problem - the control electronics had a mind of their own and had to be left at the only setting which produced a musical sound i searched online and found plenty of evidence for other owners with Sinsonido control PCB issues ...but no solutions offered, except trying to get another flaky PCB from Aria as replacement In 2014, when i started playing with an acoustic-oriented band, i had the Sinsonido converted to fretless, and i made a replacement PCB using a JFET to give me proper control of Volume and Tone. i posted the JFET preamp circuit at the other site, which had several Sinsonido threads (i hadn't found BC at that time!) The circuit provides correct biasing of the Sinsonido electret mics, full control of Volume and Tone (12 o'clock=flat; 8 o'clock=max treble-cut; 4 o'clock=max bass-cut); battery drain is approx 2 mA; no headphone output provided [FET pre, Tflat] FET-Vmid-Tflat-PBPflat.mp3 [FET pre, max treble-cut] FET-Vmid-bass-PBPflat.mp3 [FET pre, max bass-cut] FET-Vmid-Ttreble-PBPflat.mp3 NB i should emphasise that this circuit, and the 2 following, were created (or modded) to overcome faults occuring with the original Aria PCBs whilst keeping the full acoustic tones of the electret mic pickups in the original

[Edit: amp took a tumble, apparently]

Yes, my Hagström Viking bass uses the same approach (hollow body, no cavity shielding)

There's a huge choice of wire types out there: thick, thin, multicore, single-wire - all of it more than happy to pass the signal Really, the only two considerations involved are usually: A) "will the assembly need to cope with being flexed at any time"; B) "how difficult will it be to make the connections" As a very general rule of thumb, choose multicore for A), choose thinner rather than thicker for B) Cloth-covering can last longer than some plastics (which can crack with time), and usually survives unintended brushes with a soldering iron without melting or blackening - but it can be difficult to cut/trim neatly, and may not be available in a wide range of colours Personally, i'd probably use a thinnish (around 5 core?) multicore for ease of soldering good joints and general neatness of loom - i'd consider using a single core of approx 0.75-1.0mm if that was all that was available Make it easy on yourself (...er?) by getting a few decent tools, if you don't have them (60W min. iron; thin solder; sharp, adjustable wire-strippers; point-nosed pliers). Do a few test runs soldering bits of the wire to each other to get a feel for how it behaves with the solder & iron (Avoid trying to solder pot cases to ground - just ensure good and encasing shielding round all wiring routs and under coverplates, etc. Don't create any ground loops - wire up either with one ground path, or several separate ones, back to the jack shield lug - apologies, if already known!)

hi David i've been able to confirm with a dealer who has some Sinsonido product that the DC supply spec. is 9V, 200mA, centre-negative, as for effect pedals hope this helps!

i finished with my blues/rock bands just before CV19, to be free to care for my mother. i hope to play more acoustic type sets again, someday i'm hoping that infornation will be more valuable than just the parts (£70 was accepted)

Throughout the Aria** versions, the Bass body is solid Mahogany, and the neck is usually Maple (with a Rosewood fretboard, i believe) (** The Sinsonido is licensed from Soloette Inc, and their guitar versions appear to be a one-piece design, but not Mahogany) Some versions of the guitar appear to have had Mahogany neck

Yes, i'm afraid that is what i mean ...please don't tell my wife - she is helping me deliver all my old pub-band bass gear to a local school next week!

Hah - having said that Sinso body is not worth the money, the seller and i have agreed a lower offer and the bits will soon be on their way! So hopefully, i will be able to inspect the pickup in more detail, and maybe even confirm the possibility of replacing electrets, if needed, and secondly i can inspect this earlier 2001 PCB (prone to capacitor aging, and with non-standard IC circuit config), check it on my Sinso for correct operation, remove unecessary caps, and confirm that the remaining old caps can be replaced by better types and still work satisfactorily watch this space / à suivre

Nice review of the development, Thanks LW! It seems that, between the 4 of us, we have 1 of each of these variants In fact, there is still 1 later variant - it looks like @GetFletch version, but one of the controls, presumably Tone, is stacked (and therefore a different version of the PCB, too)

Good idea re. your PSU polarities - in fact, if you take your bass they may agree to confirm which DC socket pin connects to 0v (remembering it gets switched on by inserting a guitar jack!), so you will know if the socket is centre-positive (like most consumer goods, or centre-negative (like most guitar effect devices) Thanks for the heads-up re: Reverb: A used Sinsonido body might be tempting at a much lower price (& i see they accept offers) ...but unfortunately that particular part appears to be the after-effect of a car crash 😞 It's photos do, however, answer a question which Alain and i have discussed about the pickup: the 2 grub screws do not fix the piickup to the bridge, so they must only be for adjusting the pickup - probably to raise the pickup tube into the strings good luck with thd PSU investigation!

Thanks Alain, yes, that single sheet of paper is the entire manual from Aria, for the Sinsonido (Guitar and Bass) - the information there is very poor! (No indication of detail, for power supply polarity, etc) The pickups (and original guitar design) are from Soloette Inc. - as mentioned earlier, I wrote to them a few weeks ago - no reply so far I have also contacted Aria UK to ask about availability of PCBs

Greetings Basso Navo! The fundamental world is very varied and colourful, full of rhythm and tone, we look forward to sharing it with you!

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Thanks LW, yes, the passage of time has definitely been a factor in all the Sinsonido PCB woes - and some country's depts. seem to be more responsive than others 😞 Thanks also for the heads up about PCBWay, my FET circuit is out in the wild (hopefullly to be joined soon by its IC sibling, waiting in the wings) - anyone is free to capitalise on them in that way (Today i donated the bulk of my bass gear to a local school, so i'm definitely not looking to increase bass funds)

Yours is the only one out of the three which has a socket for external DC, David, so unless another BC chatter who has the same version (or later) can tell us, only a test of the board can give us the answer (the Aria 'manual' is no help) I'm happy to send you a test board which can show if there will be any improvement in sound by having a new circuit - such a test, however, will involve either cutting or unsoldering the 2 thin audio co-ax cables from the electrets to your existing board, and then subsequently having to re-solder those cables back in place if it turns out that the test board sounds the same as your existing board Swapping a test board in, and sending me your existing board would enable me to confirm the polarity needed on your external DC socket - but is this a sufficient benefit for you to warrant the possible hassle in removing and re-installing your existing board. Only you can say (i'm more than happy to help however i can)

Thanks Alain, these all sound very good to me - is it possible that the difference in bass sound between our 3 Sinsos is only due to the adjustment of the pickups under the strings? (agreed, we know that the aging caps in older version PCBs can cause other problems like oscillation, noise and non-working controls) I have also contacted Aria (UK) now to ask about availability of PCBs, although i have read that other people have tried but received no reply

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there are a couple of things you could do which might narrow down the affected section of the amp (visual check - with power off, and NO poking - of Power supply, Power Amp stage, etc. for evidence of new ventilation holes/magic smoke release in caps & power semiconductors; trying Preamp Out to FX send; trying FX In to Main Amp) ...but ultimately it's a question of weighing up a repair estimate from nearest amp tech centre with cost of replacement gear

...keep clear of the COVFEFE ! 😉

hi David, i've compared your Sinso audio with Alain's and mine - to me, it sounds very similar to the audio range which Alain gets on his Sinso (which in turn is similar to some other guitars of his - all recorded direct, no treble-cut). i can see on the waveform that your signal contains a good fundamental and some higher harmonics, so it appears that your Sinso is generating signals from both electrets ok For some reason (possibly to do with pickup adjustment?) the waveform from my Sinso includes a higher proportion of 2nd harmonic and less higher ones, so its unfiltered sound is more 'bassy'. i have noticed that the pickup on my Sinso pushes quite firmly into the strings (may be visible in my earlier photo), so it's possible that my pickup has more 'muting' action than yours and Alain's i'll wait for Alain to get an opportunity to compare and comment on your audio clip, and then we can discuss any further action

thanks for the update, David The Aria Sinsonido 'manual' is a single page, which appears to be intended to cover both the guitar and bass - it shows the position of the DC socket but gives no info about its purpose, or its polarity (just voltage & current rating) - and no label on the bass, helpfully! Unfortunately I don't have any experience of your Sinsonido version, which has a DC socket and with the controls on top (hence my request for photos of the electronics), so i can't help you confirm the polarity, unless i'm able to check a newer PCB A quick listen on 'phones to your audio clip sounds encouraging - i'll compare it with the clips Alain and i have shared (as will Alain, i'm sure), and Alain may reply here, too We know that on the earlier version PCB the signal from one of the two electrets gets lost by using a regular mono guitar lead, but Aria appear to have improved the newer version which you have (replacing age-sensitive capacitors), so it may be that they also improved the other 'features' such as the lost signal, and non-standard circuit design If you think that your PCB is still fully functional wrt its DC power input, then there seems little point in going to the lengths of removing and swapping boards for testing Still no reply from the US wrt my request for any setup/adjustment info for the electrets/pickup, but i believe that there can be a significant delay I'll get back later, with any further comments re. the audio many thanks