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less highs when engaged…

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This topic contains 10 replies, has 3 voices, and was last updated by  brach 2 months, 1 week ago.

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  • #13289 Reply

    Stabb
    Participant

    Hi,
    I just finished building a Quaverato.
    When effect is engaged, I have less high frequency content overall than when bypassed.
    Will changing dip switched change this?

    Thank You for putting together a kit that’s super well orgnaized and easy to build !!!
    Aloha from Hawaii

    #13298 Reply

    brach
    Moderator

    Only adjust the dip switches if you want to change where the crossover frequency is. Use the high and low trim pots to adjust the relative volume of each frequency band. In your case, you’ll need to adjust the trim pots until you like the sound. The original settings in the manual are just starting points…you’ll have to adjust them by ear once the solder jumpers are connected. Since your high frequency content is lower in volume then try turning the high trim pot up (clockwise) 2 or 3 turns. If you need more highs then, thy turning down (counter clockwise) the low trim pot 1.5 or 2 turns. Keep playing around with it until you like what you hear. It’s helpful to keep track of how many turns you adjust each trim pot so you can come back to the original setting for reference.
    Good luck.
    -Brach

    #13309 Reply

    Stabb
    Participant

    Hi Brach,
    Thank you for your timely replies!
    I turned the Depth to 0 and I’ve been turning the Hi and Lo trimpots.
    I can’t seem to get the sound of the pedal close to the bypassed sound.
    The trimpots don’t seem to be affecting the freqs I want.
    So I plugged the pedal into Logic Pro to look at an RTA and strummed my Strat (w/Lace Holy Grail passive pickups).
    It looks like the pedal has a bump around 200-500hz and a big rolloff above 2.5k.
    The sound is kinda like an impedance mis-match ‘loading’ situation. Could it be?
    I’ll dig up a pedal with a buffer and try putting it in line before the Quaverato.

    Also, I lost one of the 1uF Ceramic Capacitor (which of course made me nuts) so I got one from a local electronic store labeled 104k. Its slightly bigger in physical size but it fit no prob. The replacement is in the C16 slot next to the HPF dip switches. Could this be having to do with the freq response?

    I’m ok with this pedal and intend to use it but I’d like to get the effect sound closer to the bypassed sound.
    Thank You

    #13310 Reply

    Stabb
    Participant

    Hi again Zach,
    It was a ‘loading’ type thing!
    I have one of the new Fulltone OCD v2 pedals with a buffer.
    I turned on the buffer and there’s the highs!
    Actually now I gotta turn down the trimpots because now I got more stuff than I want.
    Maybe tell your customers to run a buffer or preamp before the Quav.
    Thank You!!!
    Aloha,
    Kevin (Stabb)

    #13351 Reply

    brach
    Moderator

    Kevin,
    Yes, putting a buffer before the Quaverato is something that we’ve discovered does often help. This is because of it’s lower input impedance. One option, if you didn’t want to keep a buffer before it, would be to replace R2 and R3 with larger value resistors such as 220K or so. I’m sorry about the trouble this caused you…but i’m glad you figured out how to correct it with the buffer pedal. I have started telling other customers about this, but usually customers who have this issue have low frequency loss instead of high frequency loss, so it didn’t register with me that this could be your issue too. But anyway, i’m glad it’s sorted out.
    C16 is actually a .1uF cap (not 1uf), but a 1uF will work just as well for it’s application as a filter to keep the power rails clean.
    I hope your Quaverato gives you years of good service. Let me know if you have any more questions/issues.
    -Brach

    #13361 Reply

    Stabb
    Participant

    Ok thanks, I saw R1 at 1M and was wondering how that wasn’t a high enough value.

    I guess I typoed in my post, the cap I got was labeled 104K which is .1uf right?

    I have the Quav on my pedal board now. I’ve wanted a trem pedal for while and am enjoying it very much!!!
    Altho I had re-think my gain structure by moving my ‘always on’ EP Booster to 1st position running at unity. I previously had it way down the line running hot after most of my pedals. But like a lot of pedal boards I think, configurations change every so often in the quest for tone 🙂

    Nice Pedal!!!
    Thank You Brach!!!

    #13362 Reply

    brach
    Moderator

    Kevin,
    Yes, 104 should be .1uF…but you’re good either way.
    I’m glad you’re enjoying your Quaverato!
    Take care.
    -Brach

    #13994 Reply

    YummyFuzz
    Participant

    Hello ZDL,

    I wanted to see if you could expand on your suggestion above to change R2 and R3 from 10K to 220K, on what that part of the circuit does, and how this mod affects it? I was looking to use 200K trimpots in those positions and experiment to see if I could find a happy medium for using the Quaverato on its own, or with a buffer before. Do I need to keep equal values for R2 and R3 as I experiment through the range?

    Alternatively, I see your news of version 8.2 of the schematic which looks to have some changes around the input opamp wiring, with a 1M resistor, and no 10K resistor across pins 6 and 7. Are there new mods based on lessons learned that can be made to the old circuit version to help the Quaverator “play nice” with other pedals, or is R2 and R3 still the recommendation?

    #14007 Reply

    brach
    Moderator

    YummyFuzz,
    The ratio of R3 to R2 will set the gain of the first stage. If you keep them the same this stage will have no gain (unity).
    R2 contributes to the input impedance of the pedal, so raising this to 220k (or something relatively high) will help it work better with other pedals and guitars. As you noticed, version 8.2 has some changes that uses a different topology to raise the input impedance very high, as well as a quiet switching circuit that keeps the relay click from being heard when the bypass switch is pressed. If you want to play with the first stage’s gain, I would suggest replacing R3 with a 500k trim pot. This would give you maximum gain of over 2, which is probably too much…the later stages in the circuit might start clipping, but you can always dial it down. There’s no need to use a trim pot in place of R2…it’s best to just keep this as a set resistor.
    Hopefully this answers your questions and gives you something to work with.
    Good luck.
    -Brach

    #14570 Reply

    YummyFuzz
    Participant

    Hello Brach,

    I just did this mod with R2 at 220k, and R3 as a 500k trimpot today, and wanted to report back that it does indeed get rid of the high frequency loss when the pedal is on its own, as well as helping it to work better with other pedals (my Ge Fuzz Face for example).

    Unity gain for me is when the Volume knob is around 10-11 o’clock.
    With the Depth knob at 0, starting with the trimpot set to 220k, I found the gain added a little to high, and ended up settling around 168k, which gave a nice clean transition between effect off and on tone-wise, with just a little bit of added warmth when on.

    Experimented with R3 trimpot at 50k = Unity at about 3-4 o’clock with a weedy/tinny sound. With R3 trimpot at 400k = Unity at about 8′ o’clock with a little distortion, and with the Volume knob turned up full, is quite the overdrive pedal.

    Thank you for the advice.

    Kind Regards,

    YummyFuzz

    #14625 Reply

    brach
    Moderator

    YummyFuzz,
    I’m glad to hear that mod is working for you! It sounds like you did a good job tweaking the trim pots to get the sound you want. That’s just what I hope people do with the Quavearto!
    Take care.
    -Brach

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