Double Bass Fdeck series 3 mini phase switch?

[Tom Baldwin]

I’m looking into the HPF series 3 mini, which works only with an AC adapter, no 9v battery. The comparison chart on Fdeck’s pages shows that it has all the same features as the other versions, but I don’t see a phase switch in the photo of the mini. Can anyone confirm or refute this?

 

[Francois Blais]

hpftechllc - HPF-Pre, updated April 23, 2023

HPF-Pre now comes in three versions:

1. Series 1 is the original preamp, as shown in the picture above.
   
   
2. Series 2M is the same basic audio circuit, with addition of a volume control and a LED battery indicator.
   
   
3. Series 3 uses the new "12+12" filter circuit, and has an optional DC power input, but retains the original "front panel."
   
   
4. Series 3 Mini uses the "12+12" filter circuit, has a pedalboard-friendly layout, but does not include a phase switch, battery compartment, or volume control.
   

Fourth item answers your question I think.

 

[Tom Baldwin]

Thanks Francois, I don’t know how I missed that. Had it been a snake, it would have bitten me…

Two more questions then.

1. I’ve used both the Series 1 and 2 preamps, and always have the phase switch in the same position (to the left) as it sounds better to me. Would this be akin to not having the phase reversed, thereby negating the need for the switch in my case?

2. Can someone provide a link to a recommended power supply, ideally from Amazon.

Thanks!

 

[Francois Blais]

If your amp has a phase reverse switch, then you don't need it on your preamp.
You never when you may need it...
As for the power supply, I'd suggest this: 110v AC Adaptor for Fishman Platinum Preamps

 

[Tom Baldwin]

Thanks for the link!

To clarify, I’ve always had the phase switch on the hpf-pre in the same (+)position. I don’t have a phase switch on my amp. What I’m trying to determine is, if the switch is always on the “+” position, is that the same as if there were no phase adjustment in the circuit at all. Or does “+”adjust the the phase, say 90 degrees one way and “-” adjusts it 90 degrees in the other direction.

I realize this may seem like a daft question but to the layperson (me), plus means adding, minus means subtracting and yet there is no “zero” position on the switch where you’re neither adding nor subtracting.

 

[Francois Blais]

Phase adjustment is either 0 or 180 degrees.
+ means 0 and - means 180.

 

[DoubleMIDI]

You shouldn’t see it additive but as a multiplier (+1 or -1).
Multiplying by +1 doesn’t change it, by -1 it is mirrored at zero.

There is no (fractional) wavelength time shift as a x degree phase shift needs, so 180 degrees is a bit misleading but often used.

 

[Vince Waldon]

I just think of it as "+" means normal and "-" means reversed, and it's one of my favorite features. Any given venue sounds better one way or the other, and I've also had occasion to swap it between sound check and the performance, once the venue fills with people.

 

[Don Kasper]

I. Am. Not. an. Electrical. Engineer.
But, my basic understanding of the "phase" switch, as explained to me, has to do with what direction the speaker cone first moves when receiving the signal - the speaker cone can first move "out" or "in", and the phase switch controls that first movement.(+ or -)
The sonic result is usually that one setting may help minimize (or eliminate) feedback or "hot" notes, by minimizing any inherent sympathetic(?) resonance(?) between the Bass body & strings and the speaker cone/cabinet.
Bassist/Engineer Steve Rodby spoke of the importance of this phenomenon in an interview about 15 yrs. ago. (Sorry, I can't remember which one.) It is a real thing.
Maybe Mr. Deck himself will add some Actual Knowledge to this conversation. (@fdeck )
Thanks.

 

[DoubleMIDI]

It wouldn‘t matter if the speaker is the only sound source and there is no feedback back to the top of the bass, but this is not the case as the top is always driven by the amplified sound and that influences the string vibration via the bridge and that gets back to the pickup.

 

[Roxbororob]

I "think" the mini is tailored to BG users more than DB (like I was when I bought my first).

Now that I also have DB applications I wouldn't want to do without the phase switch.

Edit: Rereading your OP you have never needed to change your phase switch on the one you already own (or have owned) so take my comment with a grain of salt!

 

[Tom Baldwin]

Ok, so

I just think of it as "+" means normal and "-" means reversed.

Ok, so if it’s always in the “+” position, it’s the same as if the phase switch were not in the circuit, thereby negating the need (in my case) for this function. Or is my logic flawed?

 

[Chris Fitzgerald]

Hi Tom, long time no see! I’m not using the FDeck these days, but during all those years I did I never liked the switch in the “minus” position and several times I was flummoxed by a thin sound only to discover that it had been accidentally moved during transport. I think you’ll be fine without the switch.

 

[Tom Baldwin]

Hi Tom, long time no see! I’m not using the FDeck these days, but during all those years I did I never liked the switch in the “minus” position and several times I was flummoxed by a thin sound only to discover that it had been accidentally moved during transport. I think you’ll be fine without the switch.

Chris, hope all is well and thanks for weighing in - glad to know I’m not alone on the switch thing!

 

[Vince Waldon]

Ok, so if it’s always in the “+” position, it’s the same as if the phase switch were not in the circuit, thereby negating the need (in my case) for this function.

That's how I would see it.