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Stingray aftermarket 2 band pre

#761
delta7fred said:
Glad you got to the bottom of it.

Out of phase coils would definitely affect both the volume and tone.

Did it come from the factory like this or has it been "got at"?
Click to expand...

The south bobbin was recently rewinded by a guitar tech, I suspect the bobbin ends were soldered to the opposite lugs, so when i followed the original drawing to join both + a - in parallel, was really doing wrong, the sound was nasty, trebbly and weak, i crossed the wires and voila, do you know what I mean?

Thanks for you support
 
#762
pacop said:
The south bobbin was recently rewinded by a guitar tech,I suspect the bobbin ends were soldered to the opposite lugs, so when i followed the original drawing to join both + a - in parallel, was really doing wrong, the sound was nasty, trebbly and weak, i crossed the wires and voila, do you know what I mean?
Click to expand...
He probably refitted the pickup, plugged it into his bench amp and being a guitar guy hit the strings once to verify it was working then moved onto the next job. A bass tech would have played it for a while (I'm sure) and would have noticed the lack of output.

I do know what you mean, there is nothing weak and feeble about a 2 band MM equipped bass!
 
#763
delta7fred said:
He probably refitted the pickup, plugged it into his bench amp and being a guitar guy hit the strings once to verify it was working then moved onto the next job. A bass tech would have played it for a while (I'm sure) and would have noticed the lack of output.

I do know what you mean, there is nothing weak and feeble about a 2 band MM equipped bass!
Click to expand...

+1, I sent both bobbins so he could check wind direction with the right one :rollno:, fortunately the winding job looks ok, he used the same awg43 wire and number of turns, so the final result is pleasant to me.

I´m looking for a copule of DIY PCBS, do you know how to get it in Europe?

Thanks.
 
#764
pacop said:
I´m looking for a copule of DIY PCBS, do you know how to get it in Europe?
Click to expand...
I used perf board from this layout IIRC Invalid Link Removed . It will be worth checking the rest of the thread to see if there are any improvements or changes to the layout.

I got the perf board from Ebay China (select Worldwide) search for prototype board. You can get it in paxolin (paper phenol based) or fibreglass.
Ebay item 281655490519 for paxolin based.
 
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#766
delta7fred said:
I used perf board from this layout IIRC Invalid Link Removed . It will be worth checking the rest of the thread to see if there are any improvements or changes to the layout.

I got the perf board from Ebay China (select Worldwide) search for prototype board. You can get it in paxolin (paper phenol based) or fibreglass.
Ebay item 281655490519 for paxolin based.
Click to expand...

Good idea, it is a nice option for testing, I founded this one that adds the protection diode and resistor.

Thanks.

StingrayBass.gif
 
#769
BassLife77 said:
Any first time builders C7 the output coupling cap is 10uF and not 1uF. If you go through that long Baja thread he realized he made a mistake and corrected it. the preamp will still work if it's 1uF but its not the MM stock cap value.
Click to expand...

BassLife, do you know the specs offhand for the exact cap types and makes? I've never built a bog-stock one, but I'd like to give it a whirl at some point.

Also, when you sub in the LT ICs do you add the series output resistor that the later MM versions have? If so, can you hear any difference from not using it?

John East published some frequency response measurements in this thread. My LTspice models agree pretty well. Here's what the model predicts including the part he didn't show, under 20Hz:

MM2B_stock-1vs10ufoutput.jpg


The blue trace is with the stock 10uF output cap, showing a -3dB point at just under 2Hz. Purple is 1uF, -3dB at 7Hz. I took the pickup model out of the equation, as that mostly matters for the high frequency part and it's a lot harder to model just right. Some of John's graphs showed "knobs at noon", mine are for nominal flattest setting.

OK, so then I looked at cranking the bass control all the way to see the effect of swapping in a 1uF cap:

MM2B_stock-1vs10ufoutput_basscranked.jpg


These preamps make a lot of low bass energy no matter how you slice it!
 
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#770
I think when Leo when plugging in caps the 10uF sounded the best. looking at that graph I see why the walls vibrate when I play. I also built several Sabre preamps and the bass is even stronger. the only cap that seemed to vary is C2. sometimes they used 2.2n which wouldn't make much of a difference. I don't use any series protection resistors before the output jack. when I had a 77 Stingray it had tants for the big caps and ceramics for the other ones
 
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#771
BassLife77 said:
I think when Leo when plugging in caps the 10uF sounded the best. looking at that graph I see why the walls vibrate when I play. I also built several Sabre preamps and the bass is even stronger. the only cap that seemed to vary is C2. sometimes they used 2.2n which wouldn't make much of a difference. I don't use any series protection resistors before the output jack. when I had a 77 Stingray it had tants for the big caps and ceramics for the other ones
Click to expand...

I heard 76-78 epoxy preamp are the best ones, I have a 79 stingray with non epoxy preamp, tants for the big caps and ceramics for small, components value are the same as Baja, I wonder why early preamps are better if the values are the same.
 
#772
it should sound exactly the same. I don't know the history of the company, they might have to start to have QC issues. They spent a lot of money on the Stingray and Sabre guitars and they flopped. I remember mine had epoxy and a big 47n ceramic cap. the electronics in your bass is 36 years old and the caps might be out of spec
 
#773
BassLife77 said:
I think when Leo when plugging in caps the 10uF sounded the best. looking at that graph I see why the walls vibrate when I play.
Click to expand...

If you're using an electrolytic cap 10uF is a better call. With a film cap 1UF is working fine for my purposes, but I typically use an HPF in my amps set much higher anyway. That illustrated rolloff depends somewhat on whether you use a volume pot after the preamp and/or what the input impedance you're driving is too. As I have said a few times in these threads, starting at or near the stock values is a good way to go.

The walls will vibrate even more when you swap a 220K in for the 100K one. That affects max bass boost potential as well as overall volume, in which case 18 volt operation makes even more sense IMHO.

I've had a blast the last few years messing with this design. It really does sound great. I'm moving on to my own 3-band design now, but I'll be keeping the MM 2-bander knockoff in my Travis Bean, for sure.
 
#774
BassLife77 said:
it should sound exactly the same. I don't know the history of the company, they might have to start to have QC issues. They spent a lot of money on the Stingray and Sabre guitars and they flopped. I remember mine had epoxy and a big 47n ceramic cap. the electronics in your bass is 36 years old and the caps might be out of spec
Click to expand...

The history tells Leo Fender did some changes in the preamp from 1976 to 1978, from 1979 ahead the preamp electronics values remains the same, later some protection diode and resistor was added, the caps in my bass are into specs +- 5% according to my DMM.
IMG_20150530_161644.jpg
 
#776
I know that some of you are using the onboard preamps in a 2 pickup situation, or even had the idea of combining two onboard preamps.
Especially those of you, who have combined MM pickups with higher Z PUs, e.g. Precision Bass, and have included an active/passive switching option:

How did you change the circuit and/or wiring to achieve satisfactory mixing of the two pickups? And to avoid cross loading of the two circuits?
Did you use two Volume pots or rather Volume and Balance to do this, and what are the pros and cons?
If you changed the placement of the Volume pot(s) to before the preamp(s) for passive usage, did that affect the sound of the preamp and in what way? Did you replace the preamp Vol with a resistor, to simulate the pot in the circuit?

My ideas so far:
I want to install a reverse Precision pickup in the neck position of my 2002 EBMM Sterling 4H, keeping the E-A section at or close to the original P-Bass placement. I want to replace the original 3-coil MM pickup and 3-band EQ with a more 'classic Stingray' sounding Alnico V PU (fixed parallel wiring) and the UncleFluffy/preEB 2-band EQ. I want to be able to switch at least the P-PU to passive (the MM-PU's passive use is rather debatable, anyway...). The 3-way switch would become a classic pickup selector (possibly even switching to passive P-bass in position 3).
My favorite setup would be different 2-band preamps/EQs for the two PUs with stacked T/B controls and a stacked Vol/Vol control for both, plus either a stacked passive Vol/Tone control, or a push-pull passive tone control and a/p switch. The EQ for the P-bass pickup should not neccessaraly be the Musicman EQ. There I would rather go for a cleaner, less colouring preamp, like the Glockenklang or others.

I've read through this entire thread now - and quite a couple of others - and found an awful lot of valuable information for my project. The TB Forum is awesome! My questions have mostly been asked before, but as far as I got, the people who wanted to do this have never actually posted any details on their finished projects. Maybe someone feels obliged to chime in and help me finding my solution.
 
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#777
pjoerg said:
I know that some of you are using the onboard preamps in a 2 pickup situation, or even had the idea of combining two onboard preamps.
Especially those of you, who have combined MM pickups with higher Z PUs, e.g. Precision Bass, and have included an active/passive switching option:

How did you change the circuit and/or wiring to achieve satisfactory mixing of the two pickups? And to avoid cross loading of the two circuits?
Did you use two Volume pots or rather Volume and Balance to do this, and what are the pros and cons?
If you changed the placement of the Volume pot(s) to before the preamp(s) for passive usage, did that affect the sound of the preamp and in what way? Did you replace the preamp Vol with a resistor, to simulate the pot in the circuit?

My ideas so far:
I want to install a reverse Precision pickup in the neck position of my 2002 EBMM Sterling 4H, keeping the E-A section at or close to the original P-Bass placement. I want to replace the original 3-coil MM pickup and 3-band EQ with a more 'classic Stingray' sounding Alnico V PU (fixed parallel wiring) and the UncleFluffy/preEB 2-band EQ. I want to be able to switch at least the P-PU to passive (the MM-PU's passive use is rather debatable, anyway...). The 3-way switch would become a classic pickup selector (possibly even switching to passive P-bass in position 3).
My favorite setup would be different 2-band preamps/EQs for the two PUs with stacked T/B controls and a stacked Vol/Vol control for both, plus either a stacked passive Vol/Tone control, or a push-pull passive tone control and a/p switch. The EQ for the P-bass pickup should not neccessaraly be the Musicman EQ. There I would rather go for a cleaner, less colouring preamp, like the Glockenklang or others.

I've read through this entire thread now - and quite a couple of others - and found an awful lot of valuable information for my project. The TB Forum is awesome! My questions have mostly been asked before, but as far as I got, the people who wanted to do this have never actually posted any details on their finished projects. Maybe someone feels obliged to chime in and help me finding my solution.
Click to expand...
I played about with this circuit a few years ago* and discovered that it likes to be fed direct from a pickup. Any resistance between the pickup and the input to it causes a roll off of the higher frequencies, if it is a constant resistance then you can compensate by adding a bypass cap in parallel with the resistor.

If it is variable then the best you could hope for is compensate for one pot position but expect you highs to be up or down at other pot position.

*I wanted the series volume to be the same as parallel from a MM style pickup, not considerably boosted, so I added a series resistor and discovered that the highs were attenuated when I selected this position whereas series with no resistor had all the highs present. I adjusted the amp volume when switching back and forth so that the difference in volume wasn't fooling my ears.
 
#778
delta7fred said:
Any resistance between the pickup and the input to it causes a roll off of the higher frequencies
Click to expand...

Thanks delta7fred, that's something, that I feared. So I'll rather stick with the aktive Vol controls + a separate control for passive use. This can be easily accomplished with a Grigsby 5-way, 4-pole switch - provided I can fit this in the Sterling's 3-way switch slot, completely separating active and passive circuits.
But this would also mean, that I have to be able to mix the two preamp signals on the output side (if I want to go with one preamp per pickup). Any thoughts on that?
 
#779
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#780
Hey guys, I was wondering if anybody here can help me out with some info in regards to the 2 band EQ.

I cannot afford a SR classic but I got a 3 band SR4 HH and I was wondering if I could remove the pre-amp and install a home made 2 band or similar.
As far as I could research John East and Aguilar are the best aftermarket alternatives but they are too expensive and I am not sure if they would work on HH configuration.

I have no problem soldering but I am really bad making circuit boards so anybody here could sell me a board and/or help me a bit with the install questions in case I have any?

I also have a Seymour Duncan STC-3M3 tone circuit that I installed on a Sterling Ray34 as wells as Sterling SUB4 (removed to sell the basses) so I would not have problem adapting a stock preamp or the SD preamp to the SR4 HH.
I see from revies that besides 3 band the SD is closer or better than the stock 2 band being used as alternative to the stock MM 2 band but you know is all subjective, so in case anybody have previous experience with the SD STC-3M3 tone circuit, how close is that to the SR 2 band EQ,
Would it worth a try on the SR HH or better go directly to the home made one?

Thank you in advance!
 

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