lemmywinks Posted February 5, 2014 Share Posted February 5, 2014 (edited) Recently bought one of these to replace the ailing pre in my SInsonido: [url="http://www.maplin.co.uk/p/mono-preamp-kit-n46fl"]http://www.maplin.co...reamp-kit-n46fl[/url] Have no idea if it's suitable for electric bass or not but it was free shipping day on Maplin and I had some Paypal funds. Sooo.. I'm going to test it by wiring it straight to the stereo pickup (in parallel), I'm ok at building stuff like this (it was very easy to do) as long as the guide is good but I'm a bit thick when it comes to wiring things up, having basically no electrical knowledge. The preamp has 6 contacts - [b]In[/b] (& [b]Gnd[/b]), [b]Out[/b] (& [b]Gnd[/b]), [b]+[/b] (& [b]Gnd[/b]). I'm assuming the piezo wires go into the In & Gnd, the Jack is wired to Out & Gnd and the 9v battery is wired to the + & Gnd? I know this will drain the battery so I will have to fit a switch jack (which arrived today) but I just wanted to test it first before complicating things further. Like I said I don't really know what I'm doing so wanted to check the pre actually works before adding anything else. Any help is appreciated, please explain things in simpleton terms (diagrams in crayon please) as any technical stuff will go right over my head. EDIT: Also one of the white block plastic capacitors was substituted with a brown ceramic one in the kit, I trust this is ok? Edited February 5, 2014 by lemmywinks Quote Link to comment Share on other sites More sharing options...
icastle Posted February 5, 2014 Share Posted February 5, 2014 [quote name='lemmywinks' timestamp='1391610114' post='2359161'] Recently bought one of these to replace the ailing pre in my SInsonido: [url="http://www.maplin.co.uk/p/mono-preamp-kit-n46fl"]http://www.maplin.co...reamp-kit-n46fl[/url] The preamp has 6 contacts - [b]In[/b] (& [b]Gnd[/b]), [b]Out[/b] (& [b]Gnd[/b]), [b]+[/b] (& [b]Gnd[/b]). I'm assuming the piezo wires go into the In & Gnd, the Jack is wired to Out & Gnd and the 9v battery is wired to the + & Gnd? [/quote] Yep spot on. [quote name='lemmywinks' timestamp='1391610114' post='2359161'] I know this will drain the battery so I will have to fit a switch jack (which arrived today) but I just wanted to test it first before complicating things further. Like I said I don't really know what I'm doing so wanted to check the pre actually works before adding anything else. Any help is appreciated, please explain things in simpleton terms (diagrams in crayon please) as any technical stuff will go right over my head. [/quote] When it comes to wiring the switch, the battery + needs to be connected permanently and the - side switched. [quote name='lemmywinks' timestamp='1391610114' post='2359161'] EDIT: Also one of the white block plastic capacitors was substituted with a brown ceramic one in the kit, I trust this is ok? [/quote] They probably just ran out of the poly ones and substituted them for the ceramic ones - won't make a huge difference in real terms as it's a simple circuit. Quote Link to comment Share on other sites More sharing options...
lemmywinks Posted February 5, 2014 Author Share Posted February 5, 2014 How would I wire the switch jack in? With the [b]Battery +[/b] wired to the [b]9v +[/b] on the preamp as usual, then the [b]Battery Gnd[/b] wired to the extra tab on the jack, then the [b]9v Gnd[/b] wired to the Gnd on the jack? Quote Link to comment Share on other sites More sharing options...
hamfist Posted February 5, 2014 Share Posted February 5, 2014 [quote name='lemmywinks' timestamp='1391615540' post='2359258'] How would I wire the switch jack in? With the [b]Battery +[/b] wired to the [b]9v +[/b] on the preamp as usual, then the [b]Battery Gnd[/b] wired to the extra tab on the jack, then the [b]9v Gnd[/b] wired to the Gnd on the jack? [/quote] Yes that's it. So long as the ground connection on the preamp is only actually connected to the -ve side of the battery when a jack is plugged in. Quote Link to comment Share on other sites More sharing options...
lemmywinks Posted February 5, 2014 Author Share Posted February 5, 2014 Cool thanks guys, expect me to be back when it doesn't work! Quote Link to comment Share on other sites More sharing options...
lemmywinks Posted February 6, 2014 Author Share Posted February 6, 2014 So yeah, said I'd be back when it doesn't work and here I am! Wired it up and just get a hum which gets louder as I turn the gain knob on the preamp, no signal at all. I desoldered the wires to the board and put little screw terminals in and get the same result.Tried it with just one side of the stereo pickup and both, same result again. Can't see what could have gone wrong on the pre side of things as it's really simple and impossible to get wrong (even for me), similarly the wires are all going where they should and the battery is functional. Any ideas? As an aside does anybody know where I can get 2 way PCB screw terminals with a 3.8mm-4mm pitch? I can only find the 5mm ones and these are too big. Thanks Steve Quote Link to comment Share on other sites More sharing options...
icastle Posted February 6, 2014 Share Posted February 6, 2014 I suspect you need to be using screened cable. Try disconnecting the pickup from the input and use screened cable for the output (you're looking for no significant hum at this point. If that works then reconnect the pickup - if the hum returns then you'll need to either replace the pickup cable with a screened one (might not be possible) or screen the entire cavity with copper tape. Quote Link to comment Share on other sites More sharing options...
lemmywinks Posted February 6, 2014 Author Share Posted February 6, 2014 The pickup cable is screened I think, it's very thin cable with a copper wrap, the hot side is attached to a grey cable and the ground is attached to black one, these are wrapped in shrink tube. There are two of these as it's a stereo pickup. I butchered some old instrument cable and used this to connect the output to the 1/4" jack but this made no difference. I'm not getting any actual bass signal at all, just a constant hum which gets louder as I turn the preamp gain up. I also tried wiring the pickup straight to the jack but couldn't hear anything, I should be able to hear something right? Tried it with the original preamp and it worked fine so the pickup is ok. Quote Link to comment Share on other sites More sharing options...
icastle Posted February 7, 2014 Share Posted February 7, 2014 The details on the Maplin site are pretty scant. Was this a ready assembled board or did you have to assemble it? Quote Link to comment Share on other sites More sharing options...
hamfist Posted February 7, 2014 Share Posted February 7, 2014 I don't think screened cable will make any difference here, as you are getting no bass signal at all at the moment. Difficult to advise at the moment. Some pics of the installation and the connections available on the preamp would be useful (although awkward to get I'm sure). Quote Link to comment Share on other sites More sharing options...
lemmywinks Posted February 7, 2014 Author Share Posted February 7, 2014 I built it from a kit and yeah there isn't much information on the Maplin site. In the box you get a parts list (with descriptions) and a good diagram along with soldering guides so that part is quite good. Will get some pictures up at tonight hopefully, lighting and 3 year old daughter permitting. Quote Link to comment Share on other sites More sharing options...
tauzero Posted February 8, 2014 Share Posted February 8, 2014 Have you connected the output signal and the battery -ve/board -ve to the right lugs on the jack socket? Quote Link to comment Share on other sites More sharing options...
icastle Posted February 8, 2014 Share Posted February 8, 2014 [quote name='lemmywinks' timestamp='1391764116' post='2360954'] I built it from a kit and yeah there isn't much information on the Maplin site. In the box you get a parts list (with descriptions) and a good diagram along with soldering guides so that part is quite good. [/quote] Ah. In which case, two things that I'd double check as a matter of course would be: 1) Did you put the capacitors (C1 and C2) in the right places - you said one of them was different to the picture? 2) Did you fit the electrolytic capacitors (C3 and C4) the right way round? Quote Link to comment Share on other sites More sharing options...
lemmywinks Posted February 8, 2014 Author Share Posted February 8, 2014 [quote name='tauzero' timestamp='1391822656' post='2361834'] Have you connected the output signal and the battery -ve/board -ve to the right lugs on the jack socket? [/quote] At the moment I have just wired it straight to a mono jack for testing, when/if I get it working I'll put a switch jack in. Everything is going to the correct tabs. Quote Link to comment Share on other sites More sharing options...
lemmywinks Posted February 8, 2014 Author Share Posted February 8, 2014 [quote name='icastle' timestamp='1391826578' post='2361853'] Ah. In which case, two things that I'd double check as a matter of course would be: 1) Did you put the capacitors (C1 and C2) in the right places - you said one of them was different to the picture? 2) Did you fit the electrolytic capacitors (C3 and C4) the right way round? [/quote] The ceramic capacitor which is different to the picture is actually listed in the manual and described in the component marking section. C1 is supposed to be a 1u polyester capacitor, C2 is supposed to be a 100n ceramic capacitor with 104 written on it. The two electrolytic capacitors are in the correct places and are the right way around, the -ve side is markd out on the board. Here's a pic: Excuse the screw terminals, I wanted to fit someafter I first discovered it didn't work so I wasn't soldering to the board all the time but couldn't find any 2 way ones with a 4mm pitch so I had to improvise. There is electrical tape around them and nothing is touching, I'm getting some proper ones next week so these are only temporary. Quote Link to comment Share on other sites More sharing options...
KiOgon Posted February 8, 2014 Share Posted February 8, 2014 What does the kit instructions say about the resistor values? Looks like you have 3 x brown/black/yellow - 100K & 1 x brown/black/red - 1K, the ones in the Maplin photo look like 4 band marking & could all be 1Ks. Quote Link to comment Share on other sites More sharing options...
lemmywinks Posted February 8, 2014 Author Share Posted February 8, 2014 (edited) R1 (the top one in the picture) is 1k, the other three are 100k. The three identical 100k ones were taped together in the kit to seperate them from the 1k one. In the component markings section R1 is labelled as brown, black, red and R2 to R4 are labelled brown, black , yellow. The instructions are actually really clear and easy to follow, I just don't understand why it doesn't work! Edited February 8, 2014 by lemmywinks Quote Link to comment Share on other sites More sharing options...
KiOgon Posted February 8, 2014 Share Posted February 8, 2014 (edited) [quote name='lemmywinks' timestamp='1391865538' post='2362116'] R1 (the top one in the picture) is 1k, the other three are 100k. The three identical 100k ones were taped together in the kit to seperate them from the 1k one. In the component markings section R1 is labelled as brown, black, red and R2 to R4 are labelled brown, black , yellow. The instructions are actually really clear and easy to follow, I just don't understand why it doesn't work! [/quote] Yes, but what I was getting at is the kit in the Maplin photo appears to have different values. Edit: What writing does the IC have on it? Can you tell what it is or does the instructions say? Edited February 8, 2014 by KiOgon Quote Link to comment Share on other sites More sharing options...
lemmywinks Posted February 8, 2014 Author Share Posted February 8, 2014 Dunno about the photo on the site, maybe they just knocked something up to show what it looked like? The parts I received match the description. IC has LM358N written on it and 6F008030, the parts list just says LM358. Quote Link to comment Share on other sites More sharing options...
icastle Posted February 8, 2014 Share Posted February 8, 2014 The LM358 is a bog standard dual op amp. Well the components are all in the right places and it looks like a tidy job. Is the underside as neat? Quote Link to comment Share on other sites More sharing options...
lemmywinks Posted February 13, 2014 Author Share Posted February 13, 2014 Just had an email from the very helpful Soloette (who Aria licensed the design of the bass and pickup from) and she said the following: [i]"[font="Arial"][size="2"]I apologize for the delayed response. We don't think this preamp will work as is since it doesn't have power going to the pickup. P[/size][/font][font="Arial"][size="2"]ower has to come to the pickup from the 9v battery. You can use 10k resistors from the 9v positive side of the battery to each microphone in the pickup. The gray wires are coming from the microphones in the pickup. Unsolder the white wire from the preamp first. Now that's it's sticking up, you will add the 10k resistor coming from the 9v+. Then add to the same junction a .01uF capacitor leading back to the input of the preamp. T[/size][/font][font="Arial"][size="2"]his will power the microphones. Do you understand? Let me know if you need more details or take this email to a tech for help. "[/size][/font][/i] So the pickup actually needs powering directly before hitting the preamp? Like I said I'm rather clueless with stuff like this so if anyone could explain it in kiddy terms that would be great. Gotta say Soloette have been very helpful while I've been trying to sort this, I messaged them a while ago and they were really god even though they didn't make the bass. Class company I think. Quote Link to comment Share on other sites More sharing options...
lemmywinks Posted February 13, 2014 Author Share Posted February 13, 2014 Also if I was wiring this as in mono rather than stereo would I need different a value resistor and capacitor? Am I right in thinking she means wire the resistor to draw power from the 9v + and then connect this to the hot wire of the pickup, then solder a capacitor to this connection and wire that to the input? Quote Link to comment Share on other sites More sharing options...
Dad3353 Posted February 14, 2014 Share Posted February 14, 2014 [quote name='lemmywinks' timestamp='1392335473' post='2367668'] Also if I was wiring this as in mono rather than stereo would I need different a value resistor and capacitor? Am I right in thinking she means wire the resistor to draw power from the 9v + and then connect this to the hot wire of the pickup, then solder a capacitor to this connection and wire that to the input? [/quote] That sounds right, and makes sense. The missing information from the start, it would seem, is that these are 'active' p/ups, and therefore need a source of power. The 10k resistor would be to 'drop' the voltage from 9v to whatever the p/up requires, and the capacitor allows the p/up signal to pass into the pre-amp, but prevents the 9v from going that way. You're nearly there. Nail-biting, isn't it..? Quote Link to comment Share on other sites More sharing options...
lemmywinks Posted February 14, 2014 Author Share Posted February 14, 2014 The only bit that confused me was she mentioned the hot wire from the pickup as being grey (which it is), then said connect the capacitor from the 9v feed onto a white wire. I assume she actually means the grey one coming from the pickup. Still not sure what the actual pickup assembly is in one of these, some people say it's a piezo but Soloette say it's a dual mic. Suppose they should know as it's their pickup! Tbh I just really want this bass to be up and running as it's a great little thing. Quote Link to comment Share on other sites More sharing options...
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