I have recently come to possess a Pignose Hog 30, which I would like to use with my bass ukulele (Self contained electric acoustic u-bass) (yes I know my ubass has it's own built in amp, but I still have the output available and I'm hoping to get even more volume).
Of course the Hog is old, and the lead acid batteries are long gone. A couple of the pots are broken from over-tightening, but these should be pretty simple to replace. But for the batteries, I am thinking to go with li-ion and improve on the run time and weight. So I am wondering: the TDA7240A amp and the NJM4558 op amp in this thing can actually take 18V, so why not run it on 18V and make it a little louder? Would this damage the rest of the circuitry? Obviously I will have to get a different charger, but I would anyway get one that matches to the battery I get. I am looking at 18Vpower tool batteries as a good option. Obviously these will run a little over 18V when full, but this should not be a problem for the chips, right?
I also found this mod: https://www.talkbass.com/threads/is-there-a-pignose-for-bass.74568/#:~:text=I've had a,resistor (was 47k). and it obviously sounds simple and desirable. So I am interested to know if there is a risk of damage to anything doing this? What about doing both - increasing the voltage and the gain mod?
See the schematic and chip datasheets attached.
Of course the Hog is old, and the lead acid batteries are long gone. A couple of the pots are broken from over-tightening, but these should be pretty simple to replace. But for the batteries, I am thinking to go with li-ion and improve on the run time and weight. So I am wondering: the TDA7240A amp and the NJM4558 op amp in this thing can actually take 18V, so why not run it on 18V and make it a little louder? Would this damage the rest of the circuitry? Obviously I will have to get a different charger, but I would anyway get one that matches to the battery I get. I am looking at 18Vpower tool batteries as a good option. Obviously these will run a little over 18V when full, but this should not be a problem for the chips, right?
I also found this mod: https://www.talkbass.com/threads/is-there-a-pignose-for-bass.74568/#:~:text=I've had a,resistor (was 47k). and it obviously sounds simple and desirable. So I am interested to know if there is a risk of damage to anything doing this? What about doing both - increasing the voltage and the gain mod?
See the schematic and chip datasheets attached.
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OK, got the new pots today and popped them in. I also found a 4.7K resistor on the shelf, so what do you think? Will it damage the amp to swap R6, the 47K one, with a 4.7k?
So I ended up replacing all three B50K pots since I had bought a pack of 5 anyway, and the one that wasn't broken was pretty noisy. I grabbed some 6V 4.0AH SLAs since that's what fits in it and put it back together. And I have to say this thing is pretty loud even with 12V, and without the gain mod. I found a couple places where things were coming loose and buzzing, and I may eventually have to replace all the screws and do some filling and re-drilling of the holes to make it tight again.
One thing I'm wondering is if a bit of damping would help in this thing - I guess most guitar cabs don't have damping, but it would seem that it would help tighten things up in the sealed back enclosure. Anyone care to comment?
One thing I'm wondering is if a bit of damping would help in this thing - I guess most guitar cabs don't have damping, but it would seem that it would help tighten things up in the sealed back enclosure. Anyone care to comment?
18V is maximum , not to be surpassed, so aim at 16/17V tops for safety.
4k7 won´t damage it, just give more gain,into Bass Fuzz territory if you wish.
Acoustic damping is useless there and may impair Chipamp cooling, so ....
Hi @JMFahey, thanks for you input. I'll keep an eye out for 16v battery options. So with the output from my uke the hog already gets pretty fuzzy, it's pretty easy to drive it to distortion. Would you say that giving it more gain will simply make it distort easier, or will it actually give it more volume before distortion. I'm obviously mostly interested in a clean sound, my music styles are mostly bluegrass, folk etc.
I really think the cabinet will also benefit from some damping as well, what do people think?
I really think the cabinet will also benefit from some damping as well, what do people think?
As J-M says: you propose to work RIGHT AT the rating. That's like standing with your foot half-off the edge of the cliff.
18V will be twice the power of 12V. Is that any louder? In hi-fi: insignificant. On guitar, fighting a calibrated drummer: maybe, but not much.
How much power is the stock speaker rated? Popular-price g-amps usually give little safety-margin on the speaker. Anyway "30 Watts" (more like 18W) is a LOT for that small speaker.
I realize the new batteries are "better". I just did a snow-job on battery that would have been absurd a few years back. But they can't work with the old chargers, so need new connectors to prevent heating/burning.
Anyway, I never saw a Pignose that wasn't "enough!" considering both loudness and play-time. Edlund and Kimbell are not as dumb as theit product looks.
Put the alarm/motorcycle battery in it and enjoy.
EDIT: I see there is almost no information about the stock battery. Do you have the old dud? Do you know if it is correct or a hack?
18V will be twice the power of 12V. Is that any louder? In hi-fi: insignificant. On guitar, fighting a calibrated drummer: maybe, but not much.
How much power is the stock speaker rated? Popular-price g-amps usually give little safety-margin on the speaker. Anyway "30 Watts" (more like 18W) is a LOT for that small speaker.
I realize the new batteries are "better". I just did a snow-job on battery that would have been absurd a few years back. But they can't work with the old chargers, so need new connectors to prevent heating/burning.
Anyway, I never saw a Pignose that wasn't "enough!" considering both loudness and play-time. Edlund and Kimbell are not as dumb as theit product looks.
Put the alarm/motorcycle battery in it and enjoy.
EDIT: I see there is almost no information about the stock battery. Do you have the old dud? Do you know if it is correct or a hack?
Hi @PRR, thanks for your help. Point taken re the voltage. And since as you say I find the Hog quite loud, I'll be using the stock batteries for now, and if I ever upgrade I'll look at a 4S lipo or similar, so 14.8V. yes, of course I would have to change charger in that case, I would get the correct charger for the battery. Btw the stock batteries are standard 6V 4.0AH SLAs, as can be plainly seen many places online, including this YouTube video:
. I actually don't have the original batteries or the original charger, but I do have a couple of those standard SLAs, which fit perfectly, and a suitable charger.
Re the speaker I can't find any info. As you can see in the pictures there is no info on the label Pignose have stuck on in place of the original. On this forum someone indicates that a Warehouse speaker would be a suitable replacement: http://www.hifi-remote.com/forums/viewtopic.php?t=100752, https://wgsusa.com/8-g8c-20-watts, but I don't even know the right impedance. It would be great to be able to swap out the speaker for a beefier one, does anyone know what would work? I suppose I could try asking Howard at Pignose, but he tried to sell me replacement B50K pots for $19 plus postage (I got 5 fo£3 on eBay, they are better quality than the originals), and he refused to send me the schematic - I found it online.
Re the speaker I can't find any info. As you can see in the pictures there is no info on the label Pignose have stuck on in place of the original. On this forum someone indicates that a Warehouse speaker would be a suitable replacement: http://www.hifi-remote.com/forums/viewtopic.php?t=100752, https://wgsusa.com/8-g8c-20-watts, but I don't even know the right impedance. It would be great to be able to swap out the speaker for a beefier one, does anyone know what would work? I suppose I could try asking Howard at Pignose, but he tried to sell me replacement B50K pots for $19 plus postage (I got 5 fo£3 on eBay, they are better quality than the originals), and he refused to send me the schematic - I found it online.
Lipo battery has cutoff voltage. If you start draining the battery below cutoff voltage
the battery can be damaged or catch on fire.
Assume your aware of this and would need some sort of battery management system.
Improving the speaker would require not buying a cheap speaker with likely
lower sensitivity than the stock speaker.
Upgrade would have higher cost.
If you want it to be louder the replacement speaker needs to be
higher sensitivity. Being for bass use it would need something
with decent xmax so it doesn't reach distortion easier.
Something with higher sensitivity would be a pro sound driver
like a maybe a Beta8a
Increasing the gain of the amplifier would make it distort faster.
pointless mod.
Hog 30 is what it is. You just buy the biggest 6volt AGM batteries you can find.
that will fit in there for more battery life
Increasing the voltage of the system risks damage to the opamps
and wont gain much power.
Even if you did increase the power the speaker would still distort just as quick.
the battery can be damaged or catch on fire.
Assume your aware of this and would need some sort of battery management system.
Improving the speaker would require not buying a cheap speaker with likely
lower sensitivity than the stock speaker.
Upgrade would have higher cost.
If you want it to be louder the replacement speaker needs to be
higher sensitivity. Being for bass use it would need something
with decent xmax so it doesn't reach distortion easier.
Something with higher sensitivity would be a pro sound driver
like a maybe a Beta8a
Increasing the gain of the amplifier would make it distort faster.
pointless mod.
Hog 30 is what it is. You just buy the biggest 6volt AGM batteries you can find.
that will fit in there for more battery life
Increasing the voltage of the system risks damage to the opamps
and wont gain much power.
Even if you did increase the power the speaker would still distort just as quick.
This amplifier, (D2 changed to an 18volt type) will run happily on a higher voltage. The decoupling capacitors must also be changed in voltage handling.
The Opamps are good for a maximum of 30volts and the TA chip 25volts.
If you do this, the amplifier will change in sound and no longer be a pignose. Is that what you really want?
The Opamps are good for a maximum of 30volts and the TA chip 25volts.
If you do this, the amplifier will change in sound and no longer be a pignose. Is that what you really want?
4 ohm speaker.
18V absolute maximum rating so don´t even approach it for safety.
25V rating is for no load no signal situation, so actually not usable here.
Op Amps are good for 30V, but here the bottleneck is the chipamp, which does the heavy work.
18V absolute maximum rating so don´t even approach it for safety.
25V rating is for no load no signal situation, so actually not usable here.
Op Amps are good for 30V, but here the bottleneck is the chipamp, which does the heavy work.
As your schematic shows, the speaker is 4 ohms. A 4 ohm speaker will allow the amp to produce about 15 watts before distortion ramps way up (with 12.5v supply) while an 8 ohm would be a bit over half that (-3dB).
If you do use lithium-ion batteries, the voltage will maintain on peaks better than lead acid, but running them dead shortens their life considerably.
A driver like the Faital Pro 8FE200-4 would give more clean bass than a typical guitar speaker like the 8" GSC you linked, which has a FS (resonant frequency) of 148Hz, almost two octaves up from the low note of your bass ukelele.
Additionally, most guitar speakers are actually designed to distort at relatively low power, at 8-15 watts the driver may be adding as much "fuzz" (harmonic distortion) as the clipping amp.
Using a driver like the 8FE200-4 you could also add a bass-reflex port to increase low frequency output.
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Hi all, thanks so much for the help. To try to summarise: increasing the voltage is possible with some circuit mods, but will change the amp sound and not gain a great deal (thanks @JonSnell Electronic and no I'm not too keen on changing the sound!). The gain mod is somewhat pointless as distortion will happen sooner (thanks @WhiteDragon)
Of course if I changed the battery to some lithium type I would get a proper unit with built in BMS, and dedicated charger, but as I said I had two of the standard 6V SLAs on the shelf, and a charger in a drawer somewhere, and they aren't that heavy, and with that little amp they last forever, so not much point modding the battery right now.
I'm intrigued by the possibility of changing out the driver though. Further searching indicates that while the schematic notes a 4ohm speaker, people have found that the speaker itself is marked 8ohm. I'll need to see if mine is marked 8ohm. @weltersys has pointed out the benefit of a 4ohm speaker, but am I right in thinking the most important spec to increase the overall volume is sensitivity, providing I make sure the Fs stays as low as possible, and the xmax is sufficient since I am playing bass through it? The FaitalPro linked looks great. I see that Ciare also makes some pretty sensitive 8inchers, such as the CME200, would this be suitable?
Of course if I changed the battery to some lithium type I would get a proper unit with built in BMS, and dedicated charger, but as I said I had two of the standard 6V SLAs on the shelf, and a charger in a drawer somewhere, and they aren't that heavy, and with that little amp they last forever, so not much point modding the battery right now.
I'm intrigued by the possibility of changing out the driver though. Further searching indicates that while the schematic notes a 4ohm speaker, people have found that the speaker itself is marked 8ohm. I'll need to see if mine is marked 8ohm. @weltersys has pointed out the benefit of a 4ohm speaker, but am I right in thinking the most important spec to increase the overall volume is sensitivity, providing I make sure the Fs stays as low as possible, and the xmax is sufficient since I am playing bass through it? The FaitalPro linked looks great. I see that Ciare also makes some pretty sensitive 8inchers, such as the CME200, would this be suitable?
Another interesting speaker I found is the Ciare 8.38 MR1. Billed as a midrange with frequency range of 400-7000Hz, but Fs is 100Hz, and the sensitivity is billed as an astonishing 100dB. Would this driver work in the Hog?
The "astonishing 100dB" sensitivity drops to around 75dB at 80 Hz ;^)
At 41 Hz (low E), your acoustic instrument probably would put out more SPL..
A 10 dB drop sounds half as loud.
For low frequency response, best to figure out the internal volume of the cabinet and compare different drivers in that space using a simulation program.
Power (voltage) or excursion will be the limitation- the Ciare 8.38 has only .25mm Xmax, at low frequency it would run out of excursion and distort even more than the Pignose amp.
Art
At 41 Hz (low E), your acoustic instrument probably would put out more SPL..
A 10 dB drop sounds half as loud.
For low frequency response, best to figure out the internal volume of the cabinet and compare different drivers in that space using a simulation program.
Power (voltage) or excursion will be the limitation- the Ciare 8.38 has only .25mm Xmax, at low frequency it would run out of excursion and distort even more than the Pignose amp.
Art
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OK, yes, true. In fact although the FaitalPro 8FE200 is nominally 95dB and the Ciare CME200 is nominally 99.5dB, the frequency plots actually look fairly similar, and the FaitalPro seems to have slightly better sensitivity in the low end.
Yes, I should probably try to calculate the volume of the enclosure and do some modelling in WinISD or something. The amp has a closed back and presumably should be considered a sealed enclosure, but in actual fact it is not completely sealed, there are a few gaps at the bottom of the back. I wonder how much this matters.
Yes, I should probably try to calculate the volume of the enclosure and do some modelling in WinISD or something. The amp has a closed back and presumably should be considered a sealed enclosure, but in actual fact it is not completely sealed, there are a few gaps at the bottom of the back. I wonder how much this matters.
Very small gaps would be equivalent to a very low tuning, which hardly would change the response from completely sealed. If the gaps don't make wheezing sounds, they probably don't matter much ;^).
The enclosure does look large enough that it could be used for bass reflex, which could bump up the <100 range as much as 6dB compared to sealed. Don't get stuck on "flat response" bass reflex tunings, porting lower than Fs and taking a sensitivity loss may be a better compromise. I especially like multiple ports for guitar/bass applications, you can cover one or more and have multiple tunings, like 100Hz three open, 75Hz one covered, 45Hz two covered, or cover all and get a higher bump in response, but a more gradual drop than below Fb.
It also looks like it might be possible to fit four 6.5" in the enclosure, which would be more than double the cone area (Sd) of an 8". Doubling cone area gives +3dB sensitivity, and allows for half the excursion to produce the same output, which may keep guitar speakers with their limited Xmax (often in the .75mm range) still in the clean range.
Four 4ohm drivers wired series parallel would be 4 ohms, allowing the amp to put out it's maximum clean power.
I bought four Eminence EC-48 6-1/2" Guitar Speakers on a Parts Express buyout years ago (Part # 299-402 $12.80 each) but never used them- the 8" in my two guitar amps are already too loud for me..
Here are the specs to compare (four would put the 1w/1m sensitivity around 99dB):
Pe: 20 Watts (RMS)
Re: 4.01 ohms
Fs: 108 Hz
Qts: .966
Qes: 1.04
Qms: 14.2
Le: .48 mH
Mms: 5.59 g
Sd:129.9cm2
Vas: .378 cu ft
SPL: 93 dB 1watt 1meter/96dB 2.83v
Physical dimensions of this speaker are:
From the back of the magnet to the front of the speaker = 2 7/8"
External diameter edge-to-edge of the basket= 6 9/16"
Speaker hole cut out diameter = 5 9/16"
Weight is 2.1Lb
Available cheap!
Art
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One lithium cell, fully charged, provides 4.2 volts.
A fully charged 4S pack, therefore, will produce 16.8 volts!
Obviously that voltage will drop under heavy load, and also once the pack is partially discharged. Still, even at full discharge, a lipo cell will produce more than 3.7 volts unloaded.
I have no idea why some tool manufacturers like to pretend that a Li cell produces only 3.7 volts.
Some tool manufacturers (Dewalt "21 V Max" series, for instance) seem to have belatedly realized that pretending the battery voltage is lower than it actually is, is not in line with the rest of their advertising hyperbole. The Dewalt "21V Max" tools use a 5-cell lithium pack, which does indeed charge up to 21 volts when full, and not loaded.
Some competing manufacturers call their own 5-cell lithium packs "18 volts", which is almost certainly a holdover from the era of NiCd and NiMH cells (1.2 volts each, so a 12-cell pack put out a nominal 18 volts). This makes even less sense, because it suggests only 3.6 volts per lithium cell!
Danger, Will Robinson, Danger! Even with the right charger, Li cells are much more prone to burst into high-temperature flames than older battery chemistries.
They not only burst into flames if over-charged, they also burst into flames for a variety of other reasons. Discharging a pack too deeply, and then attempting to recharge it, is one way.
The worst are "lipo" packs, which are really just lithium-ion batteries packaged in a thin plastic envelope. Those have been known to burst into flames simply from being left on the dashboard of a car parked in the sun in Arizona and other hot areas. They also burst into flames spontaneously if the plastic pouch is imperfectly sealed, and allows moisture to creep in. They also burst into flames (sometimes belatedly) if they suffer mechanical damage, for example, from a slight impact with a hard object.
Cordless tool batteries are the same lithium-ion guts, but rolled up and stuffed into a metal tube, which offers better protection than a flimsy plastic pouch. Still, they can and do burst into flames from time to time, and the consequences can be really bad: "While they were asleep, their Teslas burned in the garage. It’s a risk many automakers are taking seriously.": https://www.washingtonpost.com/technology/2021/08/04/tesla-fire/
Sounds like great customer service! 🙄
-Gnobuddy
Felicity Ace. Probably sank because of "high temperature flames".
https://www.autonews.com/retail/bur...is-bentleys-and-lamborghinis-sinks-rough-seas