fdecks HPF, Part II

[RoadRanger]

Hey, a question to whomever makes these - have you tried tuning the HPF circuit to put a +3db "bump" at the tuning frequency? I made a fixed frequency 12 db/oct HPF back around 1980 that had that at the -3db frequency of my cab and quite liked it .

 

[fdeck]

Hey, a question to whomever makes these - have you tried tuning the HPF circuit to put a +3db "bump" at the tuning frequency? I made a fixed frequency 12 db/oct HPF back around 1980 that had that at the -3db frequency of my cab and quite liked it .

That's actually do-able. The filter contains a gain stage, whose gain determines the amount of bump. I've set the gain so that the filter has the sharpest possible knee for a 12 dB/oct filter, referred to as Butterworth response. Increasing the gain will increase the bump, into a domain called Chebyshev response, while (in the case of my circuit) also increasing the overall gain of the filter.

 

[SunnBass]

I've got one of these (ver 3) on it's way to me as we speak.
It should be here by Tuesday, I'm so friggin' excited!!!

 

[Rickenmonster]

Silly question(maybe). Why pre-comp?

 

[silky smoove]

Takes out all of the infrasonic content that will make a compressor work harder than it needs to.

 

[kleinenenten]

My comp does almost nothing now that the FDeck Series 3 is in front of it. It still works a bit with some different settings, but for my normal stuff it barely lights up. It cleaned up my signal quite a bit, and my speakers no longer move much at all. Quite nice.

 

[RoadRanger]

That's actually do-able. The filter contains a gain stage, whose gain determines the amount of bump. I've set the gain so that the filter has the sharpest possible knee for a 12 dB/oct filter, referred to as Butterworth response. Increasing the gain will increase the bump, into a domain called Chebyshev response, while (in the case of my circuit) also increasing the overall gain of the filter.

Yah, I knew it was do-able - just curious if you had given it a try. Probably would want it switchable so you can extend the cab's flat response down a bit when you want to but still be able to tame "problem" rooms. OTOH just bumping the amp's bass knob might have the same effect close enough. I tuned mine that way partially so that it had an audible increase in low end vs an audible decrease when set up at the cab's F3.

Oh, and this was for EB, not DB - and back in the days before extended low end cabs were commonly available.

 

[LouBass]

Been meaning to post this for a bit but I've been on the road. Here's my pedal board. Note that the in and out are reversed on the fdeck as previously mentioned. Also note the micro power supply I'm using. Seems to handle this setup of pedals fine even when all are on (all minus the tuner that is).

 

[Rickenmonster]

The in and out are not reversed if you mount it upside down under your board. But that might just be me.

 

[SunnBass]

Ok, I used the search function and read thru some older posts.
But just to clarify: full volume on the series 3 should be unity gain right?
Without a way to click it on and off, finding unity may prove difficult.

 

[LouBass]

Full volume seems to be unity. I just leave it there. I have so many other ways of controlling volume the fdeck volume isn't something I use.

 

[jbybj]

Full volume seems to be unity.

That has been my observation as well.

 

[SunnBass]

Thanks!

 

[BurningSkies]

Full volume IS unity gain. No 'seems' about it.

 

[SunnBass]

So, just tried my HPF3 out. I had tried to leave my limiter out of the equation hoping the HPF would do the trick and funny thing, my speakers were going bananas. Moving more than they ever had, then my amp went into protect mode for a split second. ***? My amp seems fine but, what is going on?

Join the conversation here:
http://www.talkbass.com/threads/help-amp-went-into-protect-mode-help.1097921/

 

[mrharrell]

I'm looking at a HPF to resolve a possible issue with FOH. I play twice a month at my church, and our FOH guys are all volunteers. They put a shallow smiley face EQ on the bass channel, along with a comp ratio of 2:1, and then another shallow smiley face on the house EQ. We have a very robust system, and the lower notes do sound fantastic with this double dose of EQ + comp. However, it seems any note that isn't below the 9th fret on the E or B strings gets lost in the mix, since those lower notes are what the gain of the channel gets set at.

I'm not 100% certain putting a HPF on my bass would resolve this issue though. In theory we could put one on the board, but it gets reset after each service, so any changes could possibly be overwritten. Anyone use a HPF such as the Fdeck for this or a similar purpose?

 

[fdeck]

How new is it? If it's fairly new, then you're good. Around January 2013, I switched to a new type of op amp chip that can handle 30 Volts. This includes all current production.

Now, be sure to check the polarity of the 12 V supply. It should be negative in the middle.

The oldest units use a chip that's rated at 16 Volts, and 12 V wall warts that I've measured can go up as high as 19 Volts because their output is rated under full load.

Note: Edited to say "negative in the middle."

I'm replying to my own post because a kind soul alerted me that I got the polarity wrong my original reply. The above is correct. The power supply should be center-negative, which follows the typical convention for guitar stomp boxes.

Thankfully, there's a diode in there to protect against polarity reversal.

 

[ddnidd1]

What's the current draw on the latest version of the HPF3? If its listed somewhere, I missed it.

 

[kleinenenten]

What's the current draw on the latest version of the HPF3? If its listed somewhere, I missed it.

I was wondering this too!

 

[ddnidd1]

I just found it listed earlier in this thread as less than 10 ma.

http://www.talkbass.com/threads/fdecks-hpf-part-ii.1041058/page-8