Brett said:
No, I did not. Please read carefully.
A lot of bassists smoke grass and use heroine. I don't. So, I value as equal 100W tube amp and 800W transistor amp, exactly because when typical tratsistor amp (including Crown and other brands) starts clipping it sounds horrible. Also, I used to design amps back in 70'th with transistor outputs that sound like tube amps when overdriven. The secret is, remember of distortions and transcient processes when you design your amp.
If to be honest, some Hi-Fi tube amps also sound bad on instruments, they were built without overdrive in mind, so are "farting" when overdriven...
pinkmouse said:
Depends where you are, and what you're trying to do?.
A 100W bass amp (even a transistor one) is loud enough to cope with acoustic drums played LOUD! - if the drums are being miked through the PA then the bass should be PA'd as well, and the on-stage amp is just a stage monitor.
If you're NOT miking the drums, and running a LOT more power on the bass (and it's not turned down) then you may as well not bother bringing the drummer - as no one will hear him. Obviously the same applies to guitarists as well, who often have the habit of being far louder than everything else and the band sounds crap!.
As far as valve amps go, for the same power rating they are considerably louder - simply because distorted sound appears louder than clean sound. Personally I much prefer clean sound for bass, and wouldn't touch a valve amp - those days are LONG gone!.
Voltaic said:
It is very healthy idea, Daniel!
Ampeg SVT has very good preamp, however some mods may improve it eliminating a ground loop that causes a hum and HF oscillations in some positions of tone switches and volume all way down, also couple of resistors is needed to eliminate shortage of a preamp anode to the ground on RF.
Black ground wire from pots and switches is soldered to the nearest point on the board instead of the nearest point to the tube V3. As the result, when a volume pot is down grid of the tube V3 is connected to the ground near the tube V1. The ground wire has small, but has some resistance and inductivity, enough for feedback on very high frequencies because of big amplification factor of the V1 and V3 tube and capacitance between it's grid and anode.
Also, in the medium position of the "Bass select" switch a high frequency loop goes from cathode of the second half of V1, through capacitors C2 and C5, and middle - to lower leads of a volume pot through the same ground wire between tubes.
I use a power amp to drive a 15" speaker. I have a Crate Spa-200 and a QSC rmx-850. It's usually the preamp thats clipping not the power amp in a bass rig. We use to drive guitar rigs with power amps also. In fact a few companies made power amps for guitars that were solid state for use with preamps.
Used power amps are dirt cheap now but consider this:
If you have a 400 watt amp, what impedence speaker do you have? A 4 ohm speaker will give you more sound if the amp is designed for 4 ohm load or higher. If you have a 8 ohm cabinet, then your wattage just went down to 200 watts or so, usually. The usual thing that makes a bass amp different is the preamp section. Sometimes they have built in compression or an EQ or a shaping circuit.
So my advice is just buy an old QSC or Yamaha power amp and concentrate on the preamp. Don't worry about driving the power amp too hard because your cabinet will have to be very good to handle 400 watts of clean power. In other words, you will be spending more money on a cabinet and speakers than the power amp and maybe the preamp if you want a 8x10 cab.
Used power amps are dirt cheap now but consider this:
If you have a 400 watt amp, what impedence speaker do you have? A 4 ohm speaker will give you more sound if the amp is designed for 4 ohm load or higher. If you have a 8 ohm cabinet, then your wattage just went down to 200 watts or so, usually. The usual thing that makes a bass amp different is the preamp section. Sometimes they have built in compression or an EQ or a shaping circuit.
So my advice is just buy an old QSC or Yamaha power amp and concentrate on the preamp. Don't worry about driving the power amp too hard because your cabinet will have to be very good to handle 400 watts of clean power. In other words, you will be spending more money on a cabinet and speakers than the power amp and maybe the preamp if you want a 8x10 cab.
Looking at the arguments above... I'm in an acoustic band. The guitar player has an acoustic/electric guitar and I have an acoutic/electric bass and an electric Jazz bass. Often in small clubs there is no need to waste a channel for the bass when you can just bring a 100-200 watt rig. I have a 120 watt Hartke Kickback that struggles with a PA because at that wattage the very low notes don't have enough power. Also just because the amp is rated at 120 watts doesn't mean that it's clean at that wattage. I get clipping and feedback with the acoustic bass at 3/4 volume often. 100 watts in a bass rig is almost nothing. Add a really loud drummer and you might as well go home. Now I have a 200 watt setup with my Trace Elliot 15" cab and the SPA-200 which is actualy only 140 or so because the cab is 8 ohm. To tell you the truth that is under powered for an acoustic band with just a conga player for drums. I just bought a Carvin PB500, 500 watts at 4 ohm and 350watts at 8 ohms.
So a good rig needs about 300-400 watts, for a small club. That should give you enough headroom for a clean sound and you can always turn down if the drummer is not miked. Remember there are no drum monitors on stage usually. You have to hear or feel the drummer. Large clubs you have to go through the PA. I have seen sound guys with club PAs that have 20k watts. Even with 10k watts a 300-400 watt rig is just a monitor.
So a good rig needs about 300-400 watts, for a small club. That should give you enough headroom for a clean sound and you can always turn down if the drummer is not miked. Remember there are no drum monitors on stage usually. You have to hear or feel the drummer. Large clubs you have to go through the PA. I have seen sound guys with club PAs that have 20k watts. Even with 10k watts a 300-400 watt rig is just a monitor.
What an assinine and obnoxious comment. Were you intending it to reflect upon me? I can only assume so as you directly quoted me. It only goes to show your (lack of) character.Wavebourn said:
The rest of your comments about power, clipping and intended usage are obviously not based upon experience.
Oh, and you're not the only EE around here so that handwaving doesn't impress me either.
Carrying on the discussion of what amp, how about these digital units? Anybody using digital amps for bass?
http://www.hypex.nl/docs/UcD400_datasheet.pdf
And the other thing is building a valve preamp - I'd like to do this with the 1626 which is a great triode for tone. Any ideas how to implement it?
http://frank.yueksel.org/tubes/sheets/049/1/1626.pdf
http://www.hypex.nl/docs/UcD400_datasheet.pdf
And the other thing is building a valve preamp - I'd like to do this with the 1626 which is a great triode for tone. Any ideas how to implement it?
http://frank.yueksel.org/tubes/sheets/049/1/1626.pdf
Concerning the use of class D amp, I personnaly use a Ucd400 as a bass power amp. The preamp is a clone of the Acoustic 360 pre (http://www.lynx.bc.ca/~jc/pedals360.html).
Killer combination !
Killer combination !
My $0.02 worth
Seems to me that tube to solid state comparison is apples to oranges. If you're looking for a heavily overdriven power amplifier, then it probably is best to use one designed for an instrument. They usually roll off the low end frequencies before applying the distortion circuitry. That reduces the farting sound, but gives excellent distortion.
Professional amplifiers are great if they're not overdriven. In my gigs I used an Eden Metro (rated 600W @ 2Ohm, but then goes on to say don't use a 2Ohm speaker!) combo. That's probably changed, my Eden was a very early model. If it was a large venue (over 100 people) we'd run a preamp out through the mains (even though the Eden could handle that by itself). Otherwise we had a race to see who could get their amp the loudest first! ;-) My conclusion from this, is the mains did just great at reproduction as long as I didn't cause the mains amps to clip. Both tube and solid state are great, but they're tools, pick the one that suits you best.
--
Then I got married and sold my Eden!
Now I'm getting back into it a little. But I don't want to carry the 78lbs around, and I have a budget. To date, I'm looking at a custom built preamp (my own design, not finished, I'll post it sometime, I'd love to incorporate your ideas). It will include a tube drive stage that can be mixed into the signal, because sometimes it's nice to have a little simulated inductance on the output. A nice thick sound. But the primary signal path will be solid state. I'm also working up a 2x6.5 subs + high frequency driver as the cabinet. My goal is to be able to use it without mains in a room up to about 8m. Don't know if that's possible yet. But WinISD Pro, says I can drive a box at 140W and get 106dBl SPL @ 1 meter. So, if I understand this correctly, that'll give me 97db SPL at 8 meters. Of course apparent loudness is to be determined. That's probably a little light if you're playing with a power drummer. Especially when you factor in the damping factor of people, bar smoke, etc.
For the power amplifier, I didn't see any better deal (value) than the Behringer A500 Reference amp. Seems to get good reviews, and has enough power to drive my cabinet. Total weight? Well pushing 65 lbs as calculated. So perhaps I'll have to build my biceps again.
One other comment I have, is I prefer to have full audible range frequency reproduction in my cabinet. Really helps to punch through the mix if needed. I was amazed with the high frequency content I got out of the Eden, and really appreciated it. If you have a chance, try demo-ing a few production amps with your bass. You might be suprized, like me, how much a little mid and high frequency helps. And that was the lesson for me. Play a lot of amps with my axe (Gibson Ripper: Talk about heavy!), and then pick what fit best. If nothing is quite right, then go custom.
j
Seems to me that tube to solid state comparison is apples to oranges. If you're looking for a heavily overdriven power amplifier, then it probably is best to use one designed for an instrument. They usually roll off the low end frequencies before applying the distortion circuitry. That reduces the farting sound, but gives excellent distortion.
Professional amplifiers are great if they're not overdriven. In my gigs I used an Eden Metro (rated 600W @ 2Ohm, but then goes on to say don't use a 2Ohm speaker!) combo. That's probably changed, my Eden was a very early model. If it was a large venue (over 100 people) we'd run a preamp out through the mains (even though the Eden could handle that by itself). Otherwise we had a race to see who could get their amp the loudest first! ;-) My conclusion from this, is the mains did just great at reproduction as long as I didn't cause the mains amps to clip. Both tube and solid state are great, but they're tools, pick the one that suits you best.
--
Then I got married and sold my Eden!
Now I'm getting back into it a little. But I don't want to carry the 78lbs around, and I have a budget. To date, I'm looking at a custom built preamp (my own design, not finished, I'll post it sometime, I'd love to incorporate your ideas). It will include a tube drive stage that can be mixed into the signal, because sometimes it's nice to have a little simulated inductance on the output. A nice thick sound. But the primary signal path will be solid state. I'm also working up a 2x6.5 subs + high frequency driver as the cabinet. My goal is to be able to use it without mains in a room up to about 8m. Don't know if that's possible yet. But WinISD Pro, says I can drive a box at 140W and get 106dBl SPL @ 1 meter. So, if I understand this correctly, that'll give me 97db SPL at 8 meters. Of course apparent loudness is to be determined. That's probably a little light if you're playing with a power drummer. Especially when you factor in the damping factor of people, bar smoke, etc.
For the power amplifier, I didn't see any better deal (value) than the Behringer A500 Reference amp. Seems to get good reviews, and has enough power to drive my cabinet. Total weight? Well pushing 65 lbs as calculated. So perhaps I'll have to build my biceps again.
One other comment I have, is I prefer to have full audible range frequency reproduction in my cabinet. Really helps to punch through the mix if needed. I was amazed with the high frequency content I got out of the Eden, and really appreciated it. If you have a chance, try demo-ing a few production amps with your bass. You might be suprized, like me, how much a little mid and high frequency helps. And that was the lesson for me. Play a lot of amps with my axe (Gibson Ripper: Talk about heavy!), and then pick what fit best. If nothing is quite right, then go custom.
j
Just to add my five cents, I wonder why nobody hasn't mentioned using a soft limiter in front of the power amplifier yet? If I'd build a bass amp it would definitely include one plus a clipping indicator and a short circuit protect. And while I definitely think bass amplifiers require a lot of power, comparing those output power ratings and loudness is pretty questionable: Doesn't it all come down to speaker system's frequency response and efficiency?
For a given cabinet size you'd have to make a tradeoff between efficiency and going low.
Commercial bass cabinets are usually dimensioned with high efficiency in mind.
Trace Elliott once used a non-linear feedback network in their power amp section in order to get soft clipping behaviour.
Edit: The latter is of course only feasible with conventionla amps but not class-d.
Regards
Charles
"What drivers? How big? How loud?"
Emminence 15's with 96 ounce magnets and cast frames.
Each 15 in a 1.25 cu ft sealed box.
Loud enough to play "sane" levels and gigs outdoors.. NOT to fill an arena.
If I were to build one it would be like his but a single 15" using the Hypex UcD400 or 700. I'd use the clean amp and servo as the foundation and get some hacked up pre amp to get any "tone" changes required.
EDIT: Because anything needed for more than a large room should be PA'ed.
Emminence 15's with 96 ounce magnets and cast frames.
Each 15 in a 1.25 cu ft sealed box.
Loud enough to play "sane" levels and gigs outdoors.. NOT to fill an arena.
If I were to build one it would be like his but a single 15" using the Hypex UcD400 or 700. I'd use the clean amp and servo as the foundation and get some hacked up pre amp to get any "tone" changes required.
EDIT: Because anything needed for more than a large room should be PA'ed.
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