B.Flat Posted October 31, 2020 Share Posted October 31, 2020 I would be grateful to hear opinions on four-hole commercial preamps to be used in a P/J set-up. I understand pickup choice is an important element of this, so pickup advice also if poss. Question arises fro wanting to mod a '95 Warick Fortess One. The existing Warwick is OK but the Sadowsky, with passive tone control, beckons. 9 or 18 volt OK, I can modify the battery accomodation. Quote Link to comment Share on other sites More sharing options...
BassBunny Posted October 31, 2020 Share Posted October 31, 2020 Personally I'm a big fan of Glockenklang pre-amps. I've got 3 of them installed in various bases. You can get 2 or 3 band in 4 control format. Set flat there is no difference between active and passive. Quote Link to comment Share on other sites More sharing options...
B.Flat Posted November 1, 2020 Author Share Posted November 1, 2020 OK ,BassBunny noted, I will investigate. However, since I posted I have thought that maybe all I need to do is stack the bass/treble pots and wire in a passive tone before the preamp. Having said that, I have no idea how to wwire it. Can anybody out there help with a laymans diagram I could follow ? Quote Link to comment Share on other sites More sharing options...
BassBunny Posted November 1, 2020 Share Posted November 1, 2020 (edited) That would work if you know the values of the bass/treble pots. Regarding the passive part, the circuit is the same as a jazz/ p bass. The way John East does it is with a single spindle, dual pot so effectively a passive circuit for each pickup. Then simply wired into the inputs of the pre-amp. Or what would be even cooler is a standard 250k dual pot and you could have different passive effect on each pickup. Edited November 1, 2020 by BassBunny Quote Link to comment Share on other sites More sharing options...
Andyjr1515 Posted November 1, 2020 Share Posted November 1, 2020 I quite like the Seymour Duncan STC pre-amps. The 3-band version STC-3P uses 4 holes and I've fitted those to two basses - and I've also fitted the 2-band version, the STC-2P to my own fretless. Easy to fit, not overly expensive and work a treat... Quote Link to comment Share on other sites More sharing options...
B.Flat Posted November 1, 2020 Author Share Posted November 1, 2020 Well, Bassbunny, the bass and treble pots are 100K linear, but the rest is a bit unclear for me. Are you saying the best would be to get a 250k dual pot and wire it between the existing volume pot and the preamp ? If yes how would I do that. Is there any chance you could draw it on the circuit I included in my last post and post it back ? It is important that the passive tone works in both passive and active mode. With regard to the active bass and treble I would obtain an MEC dual concentric 100k linear pot and copy thye connections on the diagram Quote Link to comment Share on other sites More sharing options...
BassBunny Posted November 1, 2020 Share Posted November 1, 2020 25 minutes ago, B.Flat said: Well, Bassbunny, the bass and treble pots are 100K linear, but the rest is a bit unclear for me. Are you saying the best would be to get a 250k dual pot and wire it between the existing volume pot and the preamp ? If yes how would I do that. Is there any chance you could draw it on the circuit I included in my last post and post it back ? It is important that the passive tone works in both passive and active mode. With regard to the active bass and treble I would obtain an MEC dual concentric 100k linear pot and copy thye connections on the diagram I'll see if I can update the diagram tomorrow. The passive element isn't wired between any part of the existing pre-amp. It's an additional control. Quote Link to comment Share on other sites More sharing options...
B.Flat Posted November 1, 2020 Author Share Posted November 1, 2020 16 minutes ago, BassBunny said: I'll see if I can update the diagram tomorrow. The passive element isn't wired between any part of the existing pre-amp. It's an additional control. Hi, OK I am grateful for any help you can give me but only when you have time to do it. Thank you Quote Link to comment Share on other sites More sharing options...
BassBunny Posted November 1, 2020 Share Posted November 1, 2020 Not a problem. Should be able to sort it out tomorrow. Quote Link to comment Share on other sites More sharing options...
BassBunny Posted November 2, 2020 Share Posted November 2, 2020 Right here we go and hope this makes sense. This is the way John East adds the passive control to his range of pre-amps as far as i can tell. I've shown as 2 individual pots as I already had a diagram I could crop but these really represent a Dual Pot. You can use a dual gang, if you want the same amount of treble bleed on each pickup or a dual concentric if you want to be able to vary the effect separately on each pickup, (that could be pretty cool actually). Also if you want a greater effect, change the 0.047µF capacitor for a 0.1µF. Quote Link to comment Share on other sites More sharing options...
B.Flat Posted November 2, 2020 Author Share Posted November 2, 2020 That is really great, BB, it looks foolproof to me, and I am greatly indebted to you. Thank you very much !! Quote Link to comment Share on other sites More sharing options...
BassBunny Posted November 2, 2020 Share Posted November 2, 2020 Glad I could help. Hopefully it will work, can't see why not if John East does it this way, but if not it hasn't messed up the existing wiring. Quote Link to comment Share on other sites More sharing options...
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