Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: tubenit on April 15, 2014, 06:38:46 am
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Not really an acoustic guitar amp, just thought I'd pass this along for those who have an active FX loop on board. All 3 of my amps have an on board FX.
I've done this with my Larrivee acoustic & used a delay pedal set on slight delay. I just plugged into the delay pedal and then into the FX return jack. Only one gain stage prior to the LTPI then. VERY transparent acoustic tone but a warm rich tone, IMO.
Don't know if others have also done this or not, so it's just kind of an FYI. One could add a DPDT center off as a bright switch with two options if needed to control the tone.
With respect, Tubenit
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Hey T, great idea! I'll have to try it, as I've been playing acoustic more than electric at church lately. It's bound to sound better than the cheapo SS amp I'm using now.
Thanks (as always) for sharing
G
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Hey Geezer,
I am very very happy with the acoustic tone I am getting doing this! Sounds quite rich and warm to me. I just dialed down the delay somewhat & the tone is there for me. I have a 12AY7 in the FX and a 12AX7 or 5751 in the LTPI. One could pop a 12AT7 in the LTPI also.
As a side note, I have one of those beautiful round hole wooden gizmo's for my guitar. Mine is a pretty maple one.
http://www.lutehole.com/lutehole.php (http://www.lutehole.com/lutehole.php)
With respect, Tubenit
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Is that to suppress acoustic feed back?
They look real nice.
Brad :icon_biggrin:
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Is that to suppress acoustic feed back?
Yes, and they work fantastic in that regard. And there is very little volume loss acoustically unplugged with that in. And no change in tone that I can hear at all. They easily pop in or out without even having to loosen the strings.
With respect, Tubenit
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Huh, very nice. Thanks for posting that.
Brad :icon_biggrin:
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Thought I'd go ahead and post the schematic to show more clearly what I'm doing. Just an FYI
Tubenit
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Very cool....
As simple as it is, I probably never would have thought to try it.
It's officially on the list, right below - paint the shed -
Thanks!
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I just plugged into the delay pedal and then into the FX return jack. Only one gain stage prior to the LTPI then. VERY transparent acoustic tone but a warm rich tone, IMO.
Very smart to have tried it!
If you think about it, some guitar amps have 2 gain stages before the phase inverter, sometimes with tone controls, and still can distort. So your setup gives enough amplification to get good output power but not enough to distort.
You know, the big reason the 25L15 stays so clean is the 12AX7 -> 12AT7 -> 12AU7 topology. As each stage amplifies, the stage which follows it is configured to handle an ever-larger input signal, so no stage is given a signal which overloads its input. With only a single gain stage ahead of the phase inverter, your amp appoaches the same situation.
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1. What about eq?
2. Love those soundhole inserts. Especially a design which will keep my picks out of the guitar! :icon_biggrin: Could probably be adapted to hold a PU, Vol & tone controls on the Insert. Maybe this is a reason to buy a scroll saw!
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1. What about eq?
Most stock electro-acoustics have a small EQ -able preamp built in..
OR
I think this would be a good spot to insert a little preamp pedal with an onboard EQ
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SilverGun addressed it well.
EQ on the acoustic guitar.
Pedal with EQ in it. I have a TimZee overdrive pedal that I made that can be a clean mild boost and do that & has tone controls.
....... or have a mini-toggle DPDT center off switch on the FX return pot for several options of bright/mid cap.
Or add an 5E3 tone mini-pot to the FX return pot.
Lots of options.
With respect, Tubenit
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As a side note, I have one of those beautiful round hole wooden gizmo's for my guitar. Mine is a pretty maple one.
http://www.lutehole.com/lutehole.php (http://www.lutehole.com/lutehole.php)
With respect, Tubenit
I have one of those luteholes (a #2 in maple) that I no longer use. I had to go with one of the solid rubber soundhole feedback suppressors.
If anyone is interested shoot me a PM....I'll sell it shipped for $old :icon_biggrin:
G
Edit: both sold
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has anyone tried this with an acous/elec bass guitar? a friend just bought one (Ibanez ??) and he's having feedback problems on stage. that big hollow box really starts to howl when all the acoustic factors get aligned just the 'wrong' way. note: he's using a Fender SS bass amp.
:icon_biggrin:
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has anyone tried this with an acous/elec bass guitar? a friend just bought one (Ibanez ??) and he's having feedback problems on stage. that big hollow box really starts to howl when all the acoustic factors get aligned just the 'wrong' way. note: he's using a Fender SS bass amp.
He'd be best served to go Geezer's route, and cover the entire hole...
Also, if he has a sweepable mid control (common on bass amps) he might be able to EQ out some of the howl.
Most bass players have no idea how to use a parametric type EQ....that's why they are bass players :wink: :laugh: