A thrift store score cast me into learning how to play bass a month or so back.
I paid $60 for a Samick Corsair bass with hardly a mark on it and a Crate TB10 practice bass combo amp. Both circa 2004, both hardly used.
And then something dangerous happened. On a visit to a different thrift store i picked up a 50's or 60's Hammond Reverberation Speaker, which is just a Jensen P12P 12" alnico speaker in a blonde wood enclosure that looks like a small end table.
So. I cut the original connector and a foot or so of damaged wire off the end of the long hookup lead coming out of the Hammond box, took the back off the TB10, disconnected the internal 8" speaker, and jerry-rigged the Hammond to it.
Imagine my surprise when it not only sounded much better and fuller but was substantially louder.
This practice amp has a couple tl072, a ca3080 for the compressor, and a tda2030 with a small heatsink, powered by a 16-0-16 35va or so transformer. There are 7815 and 7915 to220 regulators with no heatsinks that i assume regulate power to the preamp, tone controls, and compressor.
So, Crate's advertised spec of 30w through the 8" 8-ohm original speaker is more than suspicious. It's pretty much a lie.
But it's not a BAD practice amp. It's not noisy, the compressor works real well, just the speaker sucks and the power stage is kinda limited.
So it turns out that Parts Express has an 8" woofer that has a claimed FR from 40hz to 7khz, 95db at 2.83v/1m. 90w RMS power handling. Best part? recommended sealed cabinet volume of 0.29 ft^3 for an F3 of 109hz.
So it should perform well in a cabinet right in the neighborhood of size that i already have. Though Crate built it vented, so I'll have to seal it up. At least, I don't think you can really call it ported when there are just two 1.5" holes in the baffle.
I am fully aware that a *guitar speaker has properties, some real and some imagined, that make it a useful tool for the production of "tone".
I'm pretty sure that bass speakers are more similar to high-fidelity speaker designs. Or at least, that the needs of a bass player can be well met by a speaker with a reasonably flat response from 100-3000hz or so. Particularly given the presence of tone controls. It's apparent that many bass combo amps have essentially full range response - if voiced a bit dark - and often with the ability to drop the treble 6db or entirely.
This is no longer my only bass amp. It's not even the second best. So I'm prepared to eff with it.
I went ahead and bought that woofer from P-E. I'm about ready to pull the trigger on some stuff from Apex Jr including their cheap tweeters, which should match this woofer pretty well. I have plenty of crossover network parts.
I have a couple 18-0-18 transformers that have a VA size near 80-100.
I've ordered what i hope are some genuine TDA2050 parts.
It seems like if i upgrade the transformer, the main rail capacitors (and any others requiring further safety margin), install rectifiers that can handle more current, adjust the R-C network to match the 2050 spec, and tweak the feedback resistors for higher gain, I might actually meet or exceed that 30w spec.
To tell the truth, since this woofer is rated for a peak of 180w, I think it would be kinda hilarious to try and make it as loud as i can. 100w practice amp that fits under an airline seat, anybody?
Anybody else been down this rabbit hole? Obviously not with the same amp.
I have a Gorilla TC-35 guitar amp that is actually pretty alright with all of the caps upgraded to modern low-ESR parts. Might give it the same chip and power supply upgrade.
I paid $60 for a Samick Corsair bass with hardly a mark on it and a Crate TB10 practice bass combo amp. Both circa 2004, both hardly used.
And then something dangerous happened. On a visit to a different thrift store i picked up a 50's or 60's Hammond Reverberation Speaker, which is just a Jensen P12P 12" alnico speaker in a blonde wood enclosure that looks like a small end table.
So. I cut the original connector and a foot or so of damaged wire off the end of the long hookup lead coming out of the Hammond box, took the back off the TB10, disconnected the internal 8" speaker, and jerry-rigged the Hammond to it.
Imagine my surprise when it not only sounded much better and fuller but was substantially louder.
This practice amp has a couple tl072, a ca3080 for the compressor, and a tda2030 with a small heatsink, powered by a 16-0-16 35va or so transformer. There are 7815 and 7915 to220 regulators with no heatsinks that i assume regulate power to the preamp, tone controls, and compressor.
So, Crate's advertised spec of 30w through the 8" 8-ohm original speaker is more than suspicious. It's pretty much a lie.
But it's not a BAD practice amp. It's not noisy, the compressor works real well, just the speaker sucks and the power stage is kinda limited.
So it turns out that Parts Express has an 8" woofer that has a claimed FR from 40hz to 7khz, 95db at 2.83v/1m. 90w RMS power handling. Best part? recommended sealed cabinet volume of 0.29 ft^3 for an F3 of 109hz.
So it should perform well in a cabinet right in the neighborhood of size that i already have. Though Crate built it vented, so I'll have to seal it up. At least, I don't think you can really call it ported when there are just two 1.5" holes in the baffle.
I am fully aware that a *guitar speaker has properties, some real and some imagined, that make it a useful tool for the production of "tone".
I'm pretty sure that bass speakers are more similar to high-fidelity speaker designs. Or at least, that the needs of a bass player can be well met by a speaker with a reasonably flat response from 100-3000hz or so. Particularly given the presence of tone controls. It's apparent that many bass combo amps have essentially full range response - if voiced a bit dark - and often with the ability to drop the treble 6db or entirely.
This is no longer my only bass amp. It's not even the second best. So I'm prepared to eff with it.
I went ahead and bought that woofer from P-E. I'm about ready to pull the trigger on some stuff from Apex Jr including their cheap tweeters, which should match this woofer pretty well. I have plenty of crossover network parts.
I have a couple 18-0-18 transformers that have a VA size near 80-100.
I've ordered what i hope are some genuine TDA2050 parts.
It seems like if i upgrade the transformer, the main rail capacitors (and any others requiring further safety margin), install rectifiers that can handle more current, adjust the R-C network to match the 2050 spec, and tweak the feedback resistors for higher gain, I might actually meet or exceed that 30w spec.
To tell the truth, since this woofer is rated for a peak of 180w, I think it would be kinda hilarious to try and make it as loud as i can. 100w practice amp that fits under an airline seat, anybody?
Anybody else been down this rabbit hole? Obviously not with the same amp.
I have a Gorilla TC-35 guitar amp that is actually pretty alright with all of the caps upgraded to modern low-ESR parts. Might give it the same chip and power supply upgrade.
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I don't plan to play bass through the P12P. Right now the idea for that speaker is a small single-ended tube guitar amp, built into the Hammond cabinet.
As for trying, I have disposable income and it's up to me how to dispose of it, isn't it?
The preamp, tone stack, and compressor built into it work very well.
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More to the point, if it works and i find it amusing and/or useful, how would that be throwing money away?
Aren't we here because we LIKE tinkering with audio electronics?
People throw money away on old cars all the time. They'd be better off buying a cheap modern mid-range car that is better in every way.
Aren't we here because we LIKE tinkering with audio electronics?
People throw money away on old cars all the time. They'd be better off buying a cheap modern mid-range car that is better in every way.
I was typing a presumably useful answer, but given your tantrum .... sorry, your "attitude" .... , ok, go ahead, it´s your money, burn it uselessly any way you want.
It´s your speaker too, so also burn it in the same pire, you can save 1 match.
By the way, Crate didn´t lie
Sorry you can´t read a spec sheet.
It´s your speaker too, so also burn it in the same pire, you can save 1 match.
By the way, Crate didn´t lie
The spec sheet claims "output power rating: 15W"
Sorry you can´t read a spec sheet.
In your dreams
Agree^^^ Crate didn't lie, the 30 watts on the thing refers to how much power it USES from the wall outlet to make its rated 15 watts. Also, the speaker says 30 watts by it meaning the speaker can HANDLE 30 watts, not that the amp produces 30 watts.
Hooking the amp to a larger speaker in a larger enclosure is louder I do not doubt. Your old Hammond speaker is more efficient, probably in more ways than one, so it is louder and deeper. There is a limit to how deep and full range an tiny 8" speaker can go.
So many folks have discovered that their tiny practice amps sound so much bigger when played through a 4x12 cab.
By the way, if you were to upbuild your power supply and install a TDA2050 to double the 15 watts to 30 watts, the result would only be 3 decibels louder. Not much.
Hooking the amp to a larger speaker in a larger enclosure is louder I do not doubt. Your old Hammond speaker is more efficient, probably in more ways than one, so it is louder and deeper. There is a limit to how deep and full range an tiny 8" speaker can go.
So many folks have discovered that their tiny practice amps sound so much bigger when played through a 4x12 cab.
By the way, if you were to upbuild your power supply and install a TDA2050 to double the 15 watts to 30 watts, the result would only be 3 decibels louder. Not much.
I picked up a Crate G20XL guitar amp at a hamfest for $5. It looks like that it, and the other $5 amps I got with it were the victims of a previous upgrader. I fixed the Fender Gdec, played with it for a month or so then gave it to a friend.
I will "upgrade" the Crate. I however go at upgrading from a different angle. The crate has a nice cabinet, a decent reverb tank, and a speaker of unknown usefulness. $5 for a cabinet and tank is OK in my book, everything else gets tossed. I think that open backed box is asking me for about 20 watts of screamin tube power and a "vintage" toned speaker.......
I wander the hamfests and flea markets for dead or otherwise cheap guitars, amps and music keyboards that have full size keys, usually in the under $10 range. I look at them all as parts donors.
Note that the speakers efficiency plays a large part in the volume an amp can produce. A 5 watt amp through a 100 dB speaker is about as loud as a 50 watt amp through a 90 dB speaker.
I will "upgrade" the Crate. I however go at upgrading from a different angle. The crate has a nice cabinet, a decent reverb tank, and a speaker of unknown usefulness. $5 for a cabinet and tank is OK in my book, everything else gets tossed. I think that open backed box is asking me for about 20 watts of screamin tube power and a "vintage" toned speaker.......
I wander the hamfests and flea markets for dead or otherwise cheap guitars, amps and music keyboards that have full size keys, usually in the under $10 range. I look at them all as parts donors.
Note that the speakers efficiency plays a large part in the volume an amp can produce. A 5 watt amp through a 100 dB speaker is about as loud as a 50 watt amp through a 90 dB speaker.
Tantrum? Sorry. Irks me when someone comes to my thread just to tell me they don't approve of it.
OK, read it wrong i guess. 15w is even a little hard to believe.
In your dreams
Expensive but plausible. The hard part is the power supply. There aren't a whole lot of bipolar switching power supplies with the right specs to power a single irs2092 board. There's one that came across parts express several months ago built more for at least two of them.
There's a limit, but it's further out than most people believe. You don't need a 12" or bigger transducer to reproduce the lowest frequencies a human ear can reliably hear. It's easier, but not required.
Also going from 8-ohm to 4-ohm speaker. ST claims "the TDA2050 is able to provide up to 35 W true RMS power into a 4 ohm load at THD = 0%, VS = ±18 V, f = 1 kHz and up to 32 W into an 8 ohm load at THD = 10%,
VS = ±22 V, f = 1 kHz. Moreover, the TDA2050 delivers typically 50 W
music power into a 4 ohm load over 1 sec at VS = 22.5 V, f = 1 kHz"
If i achieve 6db, that is twice as loud, no?
Of course. My experience so far with this junk suggests that the speaker i picked up from P-E is more efficient than the one i pulled out. Looking at the specs for replacement guitar speakers from jensen, celestion, and eminence in the 8" size, they seem to have similar db/v ratings to the anonymous $18 P-E woofer.
No, 6db is not twice as loud. 10db is twice as loud. And 10db is ten times the power. SO it takes 100 watts to be twice as loud as 10 watts, if all else is the same.
efficiency is the 1 watt at 1 meter reading in the spec sheet.
Assuming your new 4 ohm speaker was otherwise identical to the 8 ohm, it would try to draw twice the current from the amp at a given output voltage, and that doubles output power. The difference between 30 and 35 watts is negligible.
Well, this is conflating theory and practice. Can you use a small speaker to make really low notes? Yes, they call them subwoofers. You may have one for your TV sound system. But to do that we use a big flappy surround for lots of excursion and put it in an enclosure especially designed for that. But neither that type of speaker nor that type of enclosure are found in small practice amps. Ever try playing guitar through a subwoofer unit? Your basic 8" guitar speaker just won't hack much bottom end. Not unless you want to hop the voice coil out of the gap.
efficiency is the 1 watt at 1 meter reading in the spec sheet.
Assuming your new 4 ohm speaker was otherwise identical to the 8 ohm, it would try to draw twice the current from the amp at a given output voltage, and that doubles output power. The difference between 30 and 35 watts is negligible.
Well, this is conflating theory and practice. Can you use a small speaker to make really low notes? Yes, they call them subwoofers. You may have one for your TV sound system. But to do that we use a big flappy surround for lots of excursion and put it in an enclosure especially designed for that. But neither that type of speaker nor that type of enclosure are found in small practice amps. Ever try playing guitar through a subwoofer unit? Your basic 8" guitar speaker just won't hack much bottom end. Not unless you want to hop the voice coil out of the gap.
6db is double the sound pressure. Do we need to have an argument about how much fletcher-munson matters?
30 and 35? I thought we agreed that the original spec is really 15w.
My best bass amp at the moment is a Behringer BXL450, rated at 45w with a 10" Bugera speaker driven by (drumroll) a tda2050 with a generous heatsink, and it's way the hell louder than the crate. I haven't found a source for specs for the Bugera speaker yet, since that's basically a berhinger house brand.
I am not using a basic 8" guitar speaker.
I'm using an 8" midwoof that appears to have been designed for a small 2-way bookshelf design since it extends from 40hz to 7000hz. F3 (self-resonance) of 109hz in a sealed enclosure of 0.29 cubic feet.
Or F3 of 40hz with a 2" diameter 5" long port in .79 cubic feet.
my casual observation to date is that bass practice combos generally have a closed back, so i thought that was generally understood. it will be trivial to seal the TB10 enclosure like a drum. it may actually have more than .29 cubic feet of internal volume.
I'm considering pairing it with a tweeter of similar efficiency that is best crossed over at 3000hz. And adding a switch that can disable the tweeter. I may or may not put a 3.5khz 3db low-pass on the woofer, maybe install it along with a bypass switch for flexibility.
I have most of the stuff i need to measure speaker impedance curves and frequency response. I'm not above nefarious methods to shape the response curve if necessary. I realize there are limits to how you can shape the response of a speaker, but i've seen measured response curves of a whole lot of "cabinet simulator" circuits and dsp systems, and it sure looks like the classic bass amp has not much response below 80hz, a small hump at about 100hz, a small dip in the neighborhood of 200-400hz (middle of the piano keyboard region), and generally falls off a cliff somewhere between 3khz and 6khz.
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I have no desire to push details around either. Yes we decided the original amp made 15 watts, but your first proposal was to use a TDA2050 plus a beefier power supply and..
That is where I got the 30 watts. Then you pointed out you can get 35 watts with another configuration. My intent was to point out that getting 35 instead of 30 was a pointless improvement. Now you may have had other things in mind, but that is where I got what I was talking about.
Then:
Sound pressure and amplifier power are not the same thing, no matter how related. I would suggest we determine what increase in amplifier power is needed to cause your increase in SPL. And perhaps our argument will dissolve.
And as to the sarcasm over F-M curves, frankly I don't need it. I was genuinely trying to have a technical discussion with you, and I just lost all interest. So do whatever you like, have a nice day.
That is where I got the 30 watts. Then you pointed out you can get 35 watts with another configuration. My intent was to point out that getting 35 instead of 30 was a pointless improvement. Now you may have had other things in mind, but that is where I got what I was talking about.
Then:
Sound pressure and amplifier power are not the same thing, no matter how related. I would suggest we determine what increase in amplifier power is needed to cause your increase in SPL. And perhaps our argument will dissolve.
And as to the sarcasm over F-M curves, frankly I don't need it. I was genuinely trying to have a technical discussion with you, and I just lost all interest. So do whatever you like, have a nice day.
Yes, right on!! I wish combo amp manufacturers would state both
power wattage and speaker sensitivity in their specs. "100 watts" by itself means diddle-squat! 100 watts driving a JBL D130 (103 db sensitivity)---now THAT's *******' LOUD!! 100 watts driving a Eminence Legend (90 db sensitivity)---well, not so loud....probably not enough to keep up with a loud drummer, unless you're clipping the hell out of it.
100 watts is +20 dBW. Once you have converted an amps output power to dBW, it is simplicity itself to calculate the SPL produced by a speaker of a given sensitivity - you just add the two numbers.
In this case, 20 dBW of power feeding a speaker with 90 dB@1W sensitivity, gets you (90+20) dB SPL, or 110 dB SPL @1 metre.
110 dB is about as loud as a "chainsaw at 1 m distance" ( SPL level chart).
110 dB is also more than three hundred times as much sound power as you need to start causing hearing damage (85 dB).
Certainly 100W into a 100 dB @1W speaker would be even worse - 120 dB SPL @ 1 m, enough to cause permanent hearing damage literally instantaneously according to some sources I looked up.
At 85 dB SPL, the authorities claim you can sustain several hours of exposure without hearing damage (arguably, that limit is way too high, and was set for the convenience of the manufacturing industry rather than the protection of employees).
But, at 120 dB SPL, there is no such grace period of hours or even minutes. Damage is virtually instantaneous - by the time you hear the sound, your ears are already damaged. Even a seconds exposure could cause permanent hearing damage.
No surprise, then, that so many of those famous guitarists who used 100 W amps "back in the day", are now deaf, or suffering from severe hearing loss and tinnitus. Jeff Beck, Eric Clapton, Neil Young, Phil Collins, Pete Townshend, Brian Wilson, Chris Martin, and on and on and on. ( 8 Famous Musicians With Hearing Loss , 10 Famous Musicians With Hearing Damage )
Loud drummer? Fire him/her, or get him/her an electronic drum kit. A much better solution than being condemned to live out your life with deafness and/or tinnitus.
-Gnobuddy
Apples or Oranges?
Are we talking rock guitar or bass/acoustic guitar? If the latter, I agree with you. If guitar, the amp will be well into clipping (somewhere) regardless of its wattage
As a lapsed bassist I was always annoyed at the weight of gear I needed to haul to be heard over the guitarist with his 15W 1x12 combo. Which was well loud enough to be heard over the drummer.
Are we talking rock guitar or bass/acoustic guitar? If the latter, I agree with you. If guitar, the amp will be well into clipping (somewhere) regardless of its wattage
As a lapsed bassist I was always annoyed at the weight of gear I needed to haul to be heard over the guitarist with his 15W 1x12 combo. Which was well loud enough to be heard over the drummer.
With a fairly low crest-factor signal (bass guitar) and a built-in compressor, there's no need for that.
To the OP, I wouldn't bother with the marginal increases you can get by going from 15w to 50w.
Find a mono class D amplifier board, give it whatever SMPS is needs. Look for 3-500w.
Grab a good 8" PA speaker, tune the ports somewhere sensible and you'll have something that might not look like much, but will be very impressive to hear.
Chris
No, I dislike musicians going deaf through ignorance about the danger of excessive SPL. Being deaf is not fun, just ask any now-deaf former musician if he/she feels it was worth it.
The human race has had music for over 40,000 years, as documented by the discovery of ancient bone flutes. But going deaf in large numbers because of stupid-loud music is a recent phenomenon, going back less than a century.
Incidentally, contemporary popular music drum kits are stupid-loud, because they evolved from military drums, which in turn were extremely loud because they had to be heard, outdoors, by long columns of marching soldiers.
But the world is full of traditional drums of dozens of different varieties, none of them loud enough to deafen the musicians near them.
-Gnobuddy
I usually plug into an ART Tube MPC ( https://www.sweetwater.com/store/detail/TubeMPC ), and then go straight into our little PA.
The MPC is a nice little preamp with a compressor that is polite and unobtrusive as long as you set the knobs with some awareness of what you're doing. It's got 1/4" and balanced outputs, switchable to line or instrument level.
There's a switchable high-pass filter at 70 Hz, which I find works very well with my 5-string bass, tightening up the sound, and spending the P.A.'s output power on the frequencies that matter.
The little MPC is quite versatile (works well on bass, guitar, and vocals too.) And it's very affordable as a bonus. Nice bit of kit!
Lately I've been playing through an 8" speaker driven by 30 W of solid-state power, or sometimes a pair of old Yamaha 8" P.A. speakers driven by a larger Yamaha powered mixer (couple hundred watts, I think, though we never use most of that power).
Even 30 W is actually plenty of power for what we do. No stupid-loud SPL levels, and we go home at the end of the day with our hearing intact.
I am aware that kilowatt-level power is now commonplace among bassists. I have no comment on that.
-Gnobuddy
I'm fairly skeptical of the 15W original rating. You can't find much in the way of positive reviews of the TB10. Mostly people bitterly complaining of how anemic it is.
I suspect that manufacturers are playing fast & loose with power output numbers. Like the Peavey GT-5 battery powered guitar amp, "5 watts" they say, but the chip amp in it is rated for 0.5W max. It's a horrible little piece of poo but learning that only set me back $3.
As for 8" PA speakers, I could probably find something - i have a friend who has a retail/design/install PA business. Former roadie with decades of bench repair and speaker design experience. He probably has something on a shelf in the back. He doesn't, fwiw, have a high opinion of the amount of design and testing that goes into most bass combos and cabinets. I think his exact words were "they just stick a speaker in a box".
As i said before, i know that for the electric guitar, the FR and distortion characteristics of the speaker are a critical part of the character of the total instrument. I suspect, for example, that the propensity for a 12" paper cone to distort above about 2khz, and to have issues with the cone rippling below 200hz or so, is actually considered a feature.
But i think electric bass is pretty different from electric guitar, and that electric bass can probably be very well played through a GOOD high fidelity speaker system with a tight, stiff low end.
And i think Crate stuck a 'guitar' speaker in this bass amp. I may even try it in a free-air guitar practice amp design.
So I'm going forward with this bigger power supply + tda2050 + heatsink + more gain + 8" wide-range woofer designed for a tiny reflex enclosure plan. I have all the stuff. I think it might be pretty good at 45-50w. Even just throwing the woofer into the box with no other changes has made it a much better amp.
Going forward i might try a hundreds-of-watts class-D approach. Sure has a 1x300w module that wants a 40v single supply. There are a lot of new mean-well switching supplies that are pretty svelt and would fit in this enclosure. But that's spending another $70 or so, which i might do anyway.
Might do it in the slightly larger (and substantially better) Peavey Max 158 Bass practice combo i picked up for $7. I don't like the preamp controls as well on the 158, but the onboard tuner is above average, and the output is a respectable and believable 15W. For some reason, the 158 Bass has a TDA2050 in it, but it's implemented solidly in TDA2030 territory with a +/-22vdc supply.
Iiiinnteresting; I recently hurt a pair of cheap and fairly nasty Fender 15g practice amps, with a J-Station high-gain patch I wasn't expecting; they were previously OK [well, bearable] set clean, just to make the J audible, but now they both have nasty buzz. I guess I've fried something in the input stages by double-preamping, silly of me; they have a CD input [presumably straight to the power amp?], which would almost certainly have been a better idea than overloading something that's expecting a tiny guitar signal... anyway, I have an old record-player box with a tiny and very simple ECC83 valve amp in it; I used to hang it off an old mono PA/mixer's Send, connect its secondary out to a big ol' 15" bass cab, and run all kinds of stuff through it, and it sounded great, at house volume too. I'm thinking seriously about duplicating the little wide-band gramophone amp [maybe even twice, considering the age of the original] and installing them in the Fender carcasses...or even better, paying someone who doesn't have my dangerously little knowledge to do it properly. It may sound a silly project to some, but have you seen the price of low-wattage valve guitar combos these days? I suspect, nay contend, that it will pay for itself in quality, as well as expense [if you already have the boxes, which were £20 each].
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