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benefits of a preamp?


Jezyorkshire
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Just got a Phil Jones Flightcase and i am using an Underwood pickup , with full gain on the input of the amp the clip light doesn't light even when abusing the strings very hard with my right hand, there doesn't seem much volume and im assuming thats because of the input stage not being loaded enough? would a pre amp of the right sort solve this and also would it improve the tone spectrum of the pickup with the right impedance match? any other advise also would be good, thanks, Jez

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Hi mate, I don't know about getting more volume, but a preamp is worth trying out if you can get hold of one. I use a KK Pure Preamp with my upright and it enables me to dial in a nice tone even with the crappiest house PAs. It's got a volume & three tone controls, nice & simple, and clips onto my belt, so I can tweak the volume if the sound guy doesn't get it quite right (surreptitiously of course 😉 ).

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I don't own a Double Bass or EUB but have some experience with PJB amps,  I have an active bass and the Pre Amp on my Double Four and Session 77 is at 3 O'Clock , 

I have found the PJB Preamps like a lot of input signal and have tried this with a Zoom MS-60B and boosted the input with favourable results.

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2 hours ago, funky8884 said:

I don't own a Double Bass or EUB but have some experience with PJB amps,  I have an active bass and the Pre Amp on my Double Four and Session 77 is at 3 O'Clock , 

I have found the PJB Preamps like a lot of input signal and have tried this with a Zoom MS-60B and boosted the input with favourable results.

It would seem to me that it does need a good input signal, I can’t get the input clip light to come on with the gain full up and playing as hard as I can!

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I also have a PJB flightcase for my double bass and electric.  My pickup is a realist sound clamp, but I also have a shadow "slot into the bridge" type which is similar to an Underwood (though less good I'm told).

With the amps gain switch to passive, I have its gain knob to about 50%-75% and it is fine with either pickup (the realist has a volume control and I have that to a bout 75% too).  However, I found that one of my leads had a small fault in it which doesn't affect the active electric basses but severely attenuates the output of the high impedance piezo pickup (I haven't found the fault yet - it's just that lead doesn't work with the realist), the result being that I can't get a high enough input into the flightcase - even with max gain the red lamp won't flicker.

What I'm saying is, are you sure your lead is OK.  Try some different leads.  Failing that, see if you can borrow someone else's pickup - or someone else's amp and try the pickup into that.

The flightcase is a great amp for double basses and its input impedance is nice and high, it should work with any working piezo pickup and lead combination and without any pre-amp.  I've only tried a pre-amp once and a) it didn't improve the sound b) it was an extra thing in the chain to stop working (flat batteries in the case of that one).

Incidentally, I have never used the "active" input switch on the PJB - even my 9V active basses can't make enough input for that.  I conclude that they do like a nice fat input voltage and that the "active" input is probably for active basses with two batteries (ie the 18V ones), also I think mine sounds nicer if the red input lamp is just on the point of flashing - ie it also wants a big output from the input stage into the EQ too.

PS:  I presume you're in Yorkshire - but if that's South Yorkshire you could always drop down to Derby and try swapping around with my near identical kit.

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1 hour ago, NickA said:

...PS:  I presume you're in Yorkshire - but if that's South Yorkshire you could always drop down to Derby and try swapping around with my near identical kit.

R91KekF.gif True BC spirit at its best; good man for offering.
@Jezyorkshire: Don't forget the packet of biscuits if taking up the offer..! B|

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I use a Shadow wing pickup with a PJB Briefcase, and I find that a good pre-amp makes a huge difference to both the signal and the sound quality. I have an EDB-1 which is a great bit of kit. The notch filter is especially useful for tuning out the odd growl. I originally bought the EDB-1 because I wanted a 2-channel pre-amp to add a microphone, but I find that I get a good enough sound for my needs with just the Shadow.

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Good point

9 hours ago, pete.young said:

The notch filter is especially useful for tuning out the odd growl.

One thing the PJB amps lack is notch and low pass filtering.   It's not been an issue for me, but then tweaking the position and clamp force of the realist sound clamp modifies the sound a lot on its own; which isn't an option with a Shadow or Underwood wing pickup. 

The input impedance of the flightcase is 4MOhm; the EDB-2 gives a choice of 1, 5 or >20MOhm; I've heard 4-5MOhm is about right for most piezo pickups, but more impedance will increase the volume a bit.  Still, the underwood should still work, volume-wise, into 4MOhm.

Edited by NickA
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I have ordered a Headway EDM1 that was on offer on eBay brand new for £99, couldn't resist the temptation, i may be being over critical off the volume coming from the PJ Flightcase, my main concern was not being able to get enough signal going in to the input, this should certainly sort it!

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14 hours ago, Jezyorkshire said:

I have ordered a Headway EDM1 that was on offer on eBay brand new for £99, couldn't resist the temptation, i may be being over critical off the volume coming from the PJ Flightcase, my main concern was not being able to get enough signal going in to the input, this should certainly sort it!

Last night I turned up the pre to full on my Session 77 with a 9v active bass and there was no clipping. I will have a play with my Zoom MS 60B to find a happy amount of boost to add to my patches.

I think with a higher input signal you will notice a significant volume increase with you PJB

Edited by funky8884
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I always have an MXR microamp and Rafferty HPF Pre 2 bass preamp/adjustable high pass filter/phase switch between my 5 string db and Phil Jones briefcase. It's not for volume but just to fill out the sound. I wouldn't contemplate playing live without a preamp.

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16 minutes ago, NickA said:

Well it's a fix and you got a pre for a good price. Result!  Still a mystery why it didn't work without ...

Hi Nick, it worked without but was compromised on volume as there wasn’t enough signal going into the input, the Headway provided lots more input.

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