hello! i need help with this tube pedal concerning output, midrange and clipping
i've picked up a Bottle Rocket pedal, made by Mesa;
it's cool, but lacks midrange and headroom.
i need help to fix the loss in tone stack and maybe reduce the clipping.
theres two places in the PCB with slots to install potentiometers: one for mid (20k), other for presence adjustment (1m)
i've tried these, there was a slight difference, but i've felt there was a faint loss in the output, tried with suggested values and diff. values too... no good
also tried diming to 0 bass + treble to achieve a mid tone, but this approach also resulted in loss of output rather than resolving my need
maybe we should start by lifting the tonestack to full bypass it with raw signal?
i've picked up a Bottle Rocket pedal, made by Mesa;
it's cool, but lacks midrange and headroom.
i need help to fix the loss in tone stack and maybe reduce the clipping.
theres two places in the PCB with slots to install potentiometers: one for mid (20k), other for presence adjustment (1m)
i've tried these, there was a slight difference, but i've felt there was a faint loss in the output, tried with suggested values and diff. values too... no good
also tried diming to 0 bass + treble to achieve a mid tone, but this approach also resulted in loss of output rather than resolving my need
maybe we should start by lifting the tonestack to full bypass it with raw signal?
Attachments
Change the first plate resistor from 220k to 100k. Short across the 220k resistor before the tone stack. Use a 50k pot for midrange. After that bypass the tone sucking, I mean shaping network to the volume pot. Use a 1M pot connected to the treble wiper as per normal resistive divider operation. Should have more control on the midrange, don't forget you can turn down the bass and treble to get more mids. At least that is what I would try first.
thank you, i'll get the stuff this week and then post the results after experimenting your suggestion, in theory it seems to be a good aproach, yes
i was planning to remove bass and treble pots to see if there was some insertion recovery due to this ground lift, but after your suggestion, i'd rather try first what you've said, simply because your idea still enables tone shaping fom BT knobs/pots
thanks.
if theres more approaches, please let us know... these bottle rockets are cool, i haven't seen any discussion about modding this pedal, i rather use it stock, but it feels a bit mid scooped to my ears and to my amp, and due to this characteristic, i am kinda having a tough time to make my rig work well... theres plenty of guys who would love the mid scooped EQ, but for the kind of work i do on our band, its vital to leave the Bass and High frequencies for the other instruments. (i also like nasal-woody midhumps on guitar amplfication, i will not deny it lol)
as you said concerning lowering bass and treble knobs close to 0 to fill mid notch, as stock, the pedal gets faint low weak output, but maybe after i mod it according to your recipe, there could be more output to make it work as i need
thanks!
i was planning to remove bass and treble pots to see if there was some insertion recovery due to this ground lift, but after your suggestion, i'd rather try first what you've said, simply because your idea still enables tone shaping fom BT knobs/pots
thanks.
if theres more approaches, please let us know... these bottle rockets are cool, i haven't seen any discussion about modding this pedal, i rather use it stock, but it feels a bit mid scooped to my ears and to my amp, and due to this characteristic, i am kinda having a tough time to make my rig work well... theres plenty of guys who would love the mid scooped EQ, but for the kind of work i do on our band, its vital to leave the Bass and High frequencies for the other instruments. (i also like nasal-woody midhumps on guitar amplfication, i will not deny it lol)
as you said concerning lowering bass and treble knobs close to 0 to fill mid notch, as stock, the pedal gets faint low weak output, but maybe after i mod it according to your recipe, there could be more output to make it work as i need
thanks!
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I forgot, when replacing the first stage plate resistor a 1.5k for the cathode probably should go with it. As far as I see the first stage should clean things up a little and without tweaking the whole mess the two big losses are the 220k before the tone stack and the network afterwards.
Just for giggles, you could try using the 100k volume off the treble pot, you loose 6 dB of signal as compared to a 1M pot but you can see if the network is loosing you a lot. Heck, just short the pre-eq 220k and take the volume pot off the treble pot. Cost you nothing and might make a reasonable improvement.
Just for giggles, you could try using the 100k volume off the treble pot, you loose 6 dB of signal as compared to a 1M pot but you can see if the network is loosing you a lot. Heck, just short the pre-eq 220k and take the volume pot off the treble pot. Cost you nothing and might make a reasonable improvement.
Just all the usual ones.
Drop the cathode bypass capacitor size to move the bass cut off point up.
Remove the "bright" caps.
Bypass the tone control and post-tone control cruft completely. Or replace them with a Baxandall which can actually give mid boost.
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The tone stack is passive, meaning there will be interaction between the controls, and there will be a substantial signal attenuation, which is desirable if you want the output of the pedal to be approximately unity gain. I'd definitely add the midrange pot, and experiment with reducing the 220K R feeding the tone stack. If you want more headroom you might try removing the cathode bypass caps in the early stages and/or reducing the 33K R on the cathode of V2B to maybe half that (or less), to get that tube further away from cutoff distortion. If you're still not happy with the FR, you could mess with the multi-section EQ filter that drives the output level control.
okay, the other tips i've kinda understood, could ny1 please tell me which one is the bright cap and how could be done the mod to baxandall TS?
i've seen some generic schematics regarding modding fenders BT tone stack to baxandall, but since i'm not a pro in electronics, maybe its better to follow a specific recomendation regarding the Bottle Rocket circuit into it
i kinda know Mesa Engineering is based on fenders in some degree, but even so... well
thx anyway and i'm writing all the tips to patiently do the mods in a smart way, i'd prefer retaining the tone controls than fully bypassing the tone stack, but if theres no other way, then the stack will be skipped as a last resort
thanks!
sorry for double post, but i couldn't edit the last one to update the info;
as y'all can see on the picture attachment, i've wrote down all of your kind advices (much thanks)
then took a serious time to think about how it would be done, some new questions popped up (it might look silly and obvious, but its better to make sure ya know better safe than sorry lol)
*i see each ecc83 has 2 cathodes, 2 plates, etc.
so, lowering the first plate resistor is the 220k R from pin 6
the following cathode resistor to be working with the first plate resistor pin 6 is the first cathode known as pin 8, is this right?
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*the cathode bypass capacitor, is originally which value?
and its linked to which pinout and which one of the tubes, or both v1+v2 benefit from this change?
the bass cutoff point being moved up by decreasing the capacitor value means less bass and more mid?
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*the 220k resistor before the tone stack is the one inbetween a .047 cap and a 33k resistor with 500pf cap?
is this 200k resistor the so claimed 'slope resistor'?
can i pigback a wire on the start and end of this resistor to short it without removing/lifting one side of this resistor?
if the answer above is 'yes' will there be any resistor noise regarding this 220k been left intact just shorted, or is it better to remove it to achieve hum/noise audible reduction?
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*i choose to disconnect the bass pot 1ma to install on the mid slot (of which came stock from mesa with no pot) and then set a fixed bass cut as if the bass pot set on 0, is it possible?
if the mids pot 1m gets too high on resisting, will it begin to behave like Allen's RAW control?
(just to state: i love bass frequencies, but i prefer to leave them to other instruments to achieve better overall mix and increase the definition of the guitar... i kinda like to make the guitar big or thick with mids and not bass)
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ok, the other advices are quite clear i need not further explanation about what was brought up so far, but obviously if anyone else got more tips, all bottle rocket users might be thankful
thanks~
as y'all can see on the picture attachment, i've wrote down all of your kind advices (much thanks)
then took a serious time to think about how it would be done, some new questions popped up (it might look silly and obvious, but its better to make sure ya know better safe than sorry lol)
*i see each ecc83 has 2 cathodes, 2 plates, etc.
so, lowering the first plate resistor is the 220k R from pin 6
the following cathode resistor to be working with the first plate resistor pin 6 is the first cathode known as pin 8, is this right?
-----------------
*the cathode bypass capacitor, is originally which value?
and its linked to which pinout and which one of the tubes, or both v1+v2 benefit from this change?
the bass cutoff point being moved up by decreasing the capacitor value means less bass and more mid?
-----------
*the 220k resistor before the tone stack is the one inbetween a .047 cap and a 33k resistor with 500pf cap?
is this 200k resistor the so claimed 'slope resistor'?
can i pigback a wire on the start and end of this resistor to short it without removing/lifting one side of this resistor?
if the answer above is 'yes' will there be any resistor noise regarding this 220k been left intact just shorted, or is it better to remove it to achieve hum/noise audible reduction?
-----------
*i choose to disconnect the bass pot 1ma to install on the mid slot (of which came stock from mesa with no pot) and then set a fixed bass cut as if the bass pot set on 0, is it possible?
if the mids pot 1m gets too high on resisting, will it begin to behave like Allen's RAW control?
(just to state: i love bass frequencies, but i prefer to leave them to other instruments to achieve better overall mix and increase the definition of the guitar... i kinda like to make the guitar big or thick with mids and not bass)
---------'
ok, the other advices are quite clear i need not further explanation about what was brought up so far, but obviously if anyone else got more tips, all bottle rocket users might be thankful
thanks~
Attachments
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Yes you got it.
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I would leave them be for now, keep the changes simple at first. You will get more bass by increasing the values, less by decreasing. You already are dropping bass with the given values.
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No, the 33k is the slope resistor. All the 220k resistor really does is reduce the signal.
Yes, nice mod, just hook a wire around the two ends, no soldering needed. And if the wire is insulated and you are careful you can give one end a tug and hear how much gain it drops. No noise added by leaving it, the preamp will not know it is still in place.
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Yes, I never thought of doing that. You could get a 1M trimmer epoxy it on the board and wire it in place of the bass pot then use a midrange pot in the bass hole. That way you can open it up and adjust the bass if need be.
Yes. I doubt you would want the mid pot more than 50k.
ok, as it was said before: theres 3 slots on the pcb to install a 20k Mid pot, as stock it comes without pot;
theres a mid increase if we install a pot 'slightly' more resistive, such as 50k
but... what happens if we leave that trim slot untouched, with no mids pot, as stock?
EDIT: i've found 2 220k resistors in kinda of a tricky spot, since the schematic says its NOT the one communicating with the pin2;
i've put the board against a light source to see better the signal path, yet no clear results.
with a multimeter set to beep shorted signals, i *Think* it's the red-red-black-orange-brown on the right side of a brown brick cap, pointed with a blade on the picture attached on this post.
as yall can see the pic, the 220k resistor that must be shorted is NOT the r40, is it accurate?
(the suspected resistor to be shorted isnt labeled such as r1, r2 etc)
theres a mid increase if we install a pot 'slightly' more resistive, such as 50k
but... what happens if we leave that trim slot untouched, with no mids pot, as stock?
EDIT: i've found 2 220k resistors in kinda of a tricky spot, since the schematic says its NOT the one communicating with the pin2;
i've put the board against a light source to see better the signal path, yet no clear results.
with a multimeter set to beep shorted signals, i *Think* it's the red-red-black-orange-brown on the right side of a brown brick cap, pointed with a blade on the picture attached on this post.
as yall can see the pic, the 220k resistor that must be shorted is NOT the r40, is it accurate?
(the suspected resistor to be shorted isnt labeled such as r1, r2 etc)
Attachments
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Can't tell you much about the layout, just going by the schematic. I would think the input of the circuit is by the input jack side and the latter part of the circuit by the output jack. Otherwise you have the method used, see through the board and trace with a ohm meter. Might help out using the ohms function rather than the conductivity (beep) function because some resistance in series can still beep but 2k in the circuit will not read as 0 ohms while both will beep.
aw, thanks... i found it anyway, was that r21 non labeled as i suggested
well, i'm not sure, but it worked.
since that resistor was better than the 220k i had (mine was a brown one, striped red-red-yellow-gold)
i decided to pull it to parallel with the stock 220k first plate resistor to drop it half, it worked very well (i piggybacked it for the ease of reversing the mod if i decide to sell the pedal someday)
i had no resource to drop the 2k2 cathode to 1k5, so i piggybacked a 2k resistor in parallel to it
now that i've tested this second mod (first was bypass the 220k sucka)
i'm about to twinkle with the 33k cathode bypass v2b suggestion to see what happens;
so far i'm getting very satisfied with the results and i'm very thankful to all of you
later i'll update all experiments here and attach pictures to pile up future knowledge for everyone that uses the bottle rocket, but even so the credit goes to all of you
much thanks
well, i'm not sure, but it worked.
since that resistor was better than the 220k i had (mine was a brown one, striped red-red-yellow-gold)
i decided to pull it to parallel with the stock 220k first plate resistor to drop it half, it worked very well (i piggybacked it for the ease of reversing the mod if i decide to sell the pedal someday)
i had no resource to drop the 2k2 cathode to 1k5, so i piggybacked a 2k resistor in parallel to it
now that i've tested this second mod (first was bypass the 220k sucka)
i'm about to twinkle with the 33k cathode bypass v2b suggestion to see what happens;
so far i'm getting very satisfied with the results and i'm very thankful to all of you
later i'll update all experiments here and attach pictures to pile up future knowledge for everyone that uses the bottle rocket, but even so the credit goes to all of you
much thanks
this is true. i've tried lowering the 33k and it increased microphonics/feedback
but i liked it because it took the pedal to fuzz area. a very midrangey fuzz that i never achieved with either si/ge fuzzboxes
i'll experiment more of this v2b cathode tweaks later to shape the drive voicing, then the advice regarding lifting the high pass to make it more midsy
i havent yet installed the 50k mid pot (ive got one) and the signal is already better with the treble and bass on 0
now i'll have to close the pedal cause tomorrow i'll gig, but tonight or tomorrow morning i'll upload the pictures attachment
thanks yall
but i liked it because it took the pedal to fuzz area. a very midrangey fuzz that i never achieved with either si/ge fuzzboxes
i'll experiment more of this v2b cathode tweaks later to shape the drive voicing, then the advice regarding lifting the high pass to make it more midsy
i havent yet installed the 50k mid pot (ive got one) and the signal is already better with the treble and bass on 0
now i'll have to close the pedal cause tomorrow i'll gig, but tonight or tomorrow morning i'll upload the pictures attachment
thanks yall
the pictures concerning the mods:
the blade pointing the r21 220k pre tone stack
the r21 removed and placed in parallel with the 220k first plate resistor
the 2k resistor piggybacked with the 2k2 cathode related to the first plate resistor
i forgot to photograph the v2b 33k piggyback (great mod to achieve fuzz tones)
the mid pot i just placed between ground and central slug slot a resistor of 37k i had lying around, dunno what happened 'cause its late to crank the amp, but i know it makes diff when i experimented 50k-250k-500k-1m pots.
its a great sounding pedal, thanks everyone
the other mods recommended i'll experiment monday and beyond, i'm looking forward to make it even more mid focused, but lets see what happen tomorrow at our gig... i'm not the guy who keeps pursuing an infinite goal of perfection, if it fits well... why bother some more?
well, very thanks! i don't know how you guys feel about it, but your help really made a difference in my life, and i hope our songs get to someday make any positive change on others, to make it worth the time y'all put on this project
the blade pointing the r21 220k pre tone stack
the r21 removed and placed in parallel with the 220k first plate resistor
the 2k resistor piggybacked with the 2k2 cathode related to the first plate resistor
i forgot to photograph the v2b 33k piggyback (great mod to achieve fuzz tones)
the mid pot i just placed between ground and central slug slot a resistor of 37k i had lying around, dunno what happened 'cause its late to crank the amp, but i know it makes diff when i experimented 50k-250k-500k-1m pots.
its a great sounding pedal, thanks everyone
the other mods recommended i'll experiment monday and beyond, i'm looking forward to make it even more mid focused, but lets see what happen tomorrow at our gig... i'm not the guy who keeps pursuing an infinite goal of perfection, if it fits well... why bother some more?
well, very thanks! i don't know how you guys feel about it, but your help really made a difference in my life, and i hope our songs get to someday make any positive change on others, to make it worth the time y'all put on this project
Attachments
22k, it gave me a good fuzz tone, i can picture you where in the back of PCB you should place it to make things easier, so you dont even need to dismount/disassemble the pedal
i just unmade the v2b mod because i already run a dirty single channel BHHD-12 slightly modded, so the bottle rocket is meant to be a slight organic boost, the v2b mod brought me some feedback/microphonics, but not much
maybe on clean amps its the way to go
btw, as i announced on our band facebook page, we recorded the gig live this sunday 8th so i can upload the results real soon (as soon as i sync/ finish the media... we plan to release this 11 songs as a lo-fi/average quality demo album... not so professional as the warpaint songs mix/masters or new jack white recordings on vinyl with zero compression claims, yet more defined and clear than Burzum - Filosofem album)
this pedal was used like 65% of the time
the impression i had live today is that it surely got volume/output increasement as well as more mids than before (i changed the mid resistor mod again from 37-39k to 220k)
this increase on shunted resistance to ground made the treble pot less effective related to increase highs to 10, but it still cuts the highs if set on 0, as i use it.
the bass control still adds some volume output, as it did before all the mods, but i no longer needed to increase bass to balance the volume... before the mods i had to set bass a little before halfway (say 10 o clock) but the pedal no longer decreases the volume when engaged, so i also zeroed the bass pot/knob to go more midrangey
what can i say is that maybe we need to work a little more on this bottle rocket project, to set it more on mid frequencies, so i can lower the mid resistor placed on the mids trimpot pcb slot and have more controls on treble/bass
not that i use the highs/low settings now, but with more resources i can rely on it to use as a preamp to record other instruments and do other things with the bottle rocket besides using on guitar as mid/gain boost on future projects.
but overall i'm satisfied with the bottle rocket now and it works fine for this one-trick
feel free to ask any info or picture thats on my reach to provide you, its a pleasure to share
i just unmade the v2b mod because i already run a dirty single channel BHHD-12 slightly modded, so the bottle rocket is meant to be a slight organic boost, the v2b mod brought me some feedback/microphonics, but not much
maybe on clean amps its the way to go
btw, as i announced on our band facebook page, we recorded the gig live this sunday 8th so i can upload the results real soon (as soon as i sync/ finish the media... we plan to release this 11 songs as a lo-fi/average quality demo album... not so professional as the warpaint songs mix/masters or new jack white recordings on vinyl with zero compression claims, yet more defined and clear than Burzum - Filosofem album)
this pedal was used like 65% of the time
the impression i had live today is that it surely got volume/output increasement as well as more mids than before (i changed the mid resistor mod again from 37-39k to 220k)
this increase on shunted resistance to ground made the treble pot less effective related to increase highs to 10, but it still cuts the highs if set on 0, as i use it.
the bass control still adds some volume output, as it did before all the mods, but i no longer needed to increase bass to balance the volume... before the mods i had to set bass a little before halfway (say 10 o clock) but the pedal no longer decreases the volume when engaged, so i also zeroed the bass pot/knob to go more midrangey
what can i say is that maybe we need to work a little more on this bottle rocket project, to set it more on mid frequencies, so i can lower the mid resistor placed on the mids trimpot pcb slot and have more controls on treble/bass
not that i use the highs/low settings now, but with more resources i can rely on it to use as a preamp to record other instruments and do other things with the bottle rocket besides using on guitar as mid/gain boost on future projects.
but overall i'm satisfied with the bottle rocket now and it works fine for this one-trick
feel free to ask any info or picture thats on my reach to provide you, its a pleasure to share
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