Bass guitar amplifier.

[Voltaic]

Hello,

I've got a question for all the gurus out there that are more enlightened than me: I'd like to build and amplifier for my bass, but as I'm sure everyone knows it's much harder to find information regarding DIY bass amps vs. guitar amps, so it's been somewhat of a wild goose chase trying to find information, so I thought maybe someone here would have some suggestions.

I've been looking at a lot of different options, and so far I'm starting to think that doing something with a tube preamp, and a SS power amp might be the best way to go for a balance of clean sound, warm tones, and a decent amount of headroom. I really like the idea of using a 1972 ampeg SVT preamp which uses 2x 12AX7, and 2x 12AU7 tubes, and backing it with something like an aussie amp 800W SS power amp, but I'm looking for some feedback/suggestions to this idea.

I'm not in a hurry to build this amp right now as I'm going to do it to replace my current amp once I move to the UK in one months time as it's not really feasible for me to ship an amp overseas (not to mention I'd just like to build my own amp as well), so I've got plenty of time to do reasearch, and make some decisions.

If anyone has any info that might help me out I'd greatly appreciate it.

cheers,
Daniel

 

[Nigel Goodwin]

It's really down to personal choice?, and what YOU want, personally I prefer the clean sound of all solid state for bass!.

If you're building a valve preamp though at least it keeps the costs down, they charge stupid amounts for adding a valve to a preamp!.

Have you considered building JUST a preamp?, and feed it to a PA slave amp, like the Behringer EP1500 and others - this is quite a popular method these days.

You might also have a look at this which is a popular FET preamp - you could throw that together VERY quickly, and test it via an existing power amp!.

What sort of band are you in to require 800W of bass anyway?, don't you run it through the PA for big gigs?.

 

[Voltaic]

Honestly I don't really need 800Watts, I don't play gigs often more like get a bunch of people over and have a jam session with no PA, and I was considering building something like an 8-10" cab, but stepping back and looking at thinks more realistically I'd probably be better off keeping it down to 400W and if I need it louder, like you said, paly it through a PA.

when you said build just the preamp, this is actually what I was planning on doing first, and then later on build the SS power amp. but I'd like to have everything planned out before I even so much as buy a transformer or tube, or anything for that matter.

 

[Voltaic]

also, Bryan James over at AX84 built a nice bass preamp designed around channel 2 of the SVT, and I like that idea, but unfortunately his website is down, and I havent been able to contact him for more imforation.

 

[Nigel Goodwin]

Honestly I don't really need 800Watts, I don't play gigs often more like get a bunch of people over and have a jam session with no PA, and I was considering building something like an 8-10" cab, but stepping back and looking at thinks more realistically I'd probably be better off keeping it down to 400W and if I need it louder, like you said, paly it through a PA.

when you said build just the preamp, this is actually what I was planning on doing first, and then later on build the SS power amp. but I'd like to have everything planned out before I even so much as buy a transformer or tube, or anything for that matter.

Do you have any sort of power amp you can use to test a preamp?.

As for power, it obviously depends on where you are playing, and what you are using - but if you're NOT miking the drums through a PA you don't need 400W. And if you ARE miking the drums through the PA you can DI the bass through it as well, so you still don't need 400W.

Essentially the amps on stage are competing with the acoustic noise of the drums - miked or not.

Using a big guitar or bass amp can be useful, as you can run it turned down - but generally people (particularly guitarists!) won't turn down!. The result is the bands balance sounds crap, and the drummer may as well have stayed at home - and of course the bass player turns up to compete with the guitarist, and the drummer loses out still further!.

For my daughter band we run 60W for guitar (1x12) and 120W bass (1x12), both solid state - it sounds great, and balances the acoustic sound of the drums nicely.

Most (all?) gig's we mike the drums through the PA, and DI both guitar and bass as well - this gives ME more control over the total sound, although most of the volume comes direct from the acoustic drums and bass/guitar combo's.

 

[Twaksak]

Bass guitar amplifier

Hi there, I have recently build a bass guitar amplifier for a friend using the following method: Dual Subwoofer amplifiers driving a dual 15" speaker cabinet. Active tone controls for bass, mid and treble. Raw DC power supplies with 4 x 4700uf per supply. Rail voltages per amp at +-33VDC. I am no expert but they play weekend gigs and he is very satisfied.

The basis of the project is solid state bipolar actives, the bass amplifier must be free from distortion and about 250W (RMS) seems sufficient. And of course an output for PA mixing.


Cheers
Chris

 

[amperex]

I would not want tube overdrive sonics

I say go with a powerful solid-state amp with carefully selected speakers for deep & accurate bass sonics. A powerful amp does not need to be turned up all the way & would have plenty of dynamic headroom at lower volumes.

 

[Twaksak]

Speaker Choice

The truth is in you Amperex. A decent 15" driver and a distortion free solid state amp is the way to go. Something like a current dumping output stage is quite acceptable for bass.

 

[willy]

Enough Power

I play a 200W with one 15" speaker. It handles outdoor gigs quite well. So 250W should be satisfactory for you. 800W probably a little much.

 

[Twaksak]

Circuit for bass amp

How about a circuit for bass amp. Does anybody have a nice one? Then choice for active or passive crossover. Should all be inside one enclosure then maybe we dont need a protection circuit in the amplifier because the speaker is always connected. Speaker protection could be the DC protection and anti thumping. What now about tone controls. This can become a project that can be used on home theater subwoofer as well.

The open E string frequency for bass guitar is 41.2 HZ (as I read on Rod Elliott's site), and most power decent amplifiers can boast with a min frequeny of 20 HZ

Just asking....

Chris

 

[Twaksak]

Time is running out

Hi Voltiac

As you stated: "I'm not in a hurry to build this amp right now as I'm going to do it to replace my current amp once I move to the UK in one months time as it's not really feasible for me to ship an amp overseas (not to mention I'd just like to build my own amp as well), so I've got plenty of time to do reasearch, and make some decisions."

One month is not a very long time to do design, build a prototype for testing, find a suitable driver, make a cabinet (make it look nice with fake leather etc) and put all together.

Chris

 

[Voltaic]

The one month is just for research I just got back from out of town, so I'm going to read over the posts and give me thoughts~

 

[Voltaic]

I appreciate all the replies, and this is what I'm thinking, designing a preamp around the ampeg SVT (schematic here: http://www.drtube.com/schematics/ampeg/svtpre-jp.gif ) and then doing a smaller solid state power amp, I've thought a lot about how big the power amp should be and I'm more or less agreeing with the other posters here and thinking maybe something around 100-200 watts would be fine, and hey I'll build the amp and preamp seperate, I could always build a bigger power amp later on. I was looking at the 150 watt aussie amp for the power amp, because it's cheap and I've heard good things about it, but as always I'm open to suggestions from others.. so if anyone out there has any good power amp designs they'd like to share, I'm all ears.

cheers,
Daniel

EDIT: also, it needs to respond down to at least 36.71Hz because that's open D, in dropped D tuning

 

[Nigel Goodwin]

EDIT: also, it needs to respond down to at least 36.71Hz because that's open D, in dropped D tuning

Don't worry about it, that's no problem for a transistor amp! - however, you should be aware that most speakers don't work well that low, including bass cabinets designed for 5 string bass.

But it still sounds OK, Melissa's 5 string sounds fine through her 1x12 Behringer combo!.

 

[Voltaic]

it's a shame I can't take my bigger stuff with me over to the UK, I've got a 2x10 cab that would work great for this, but... oh well I suppose, unless anyone owns a freight company and will trade the cost of freight from Detroit to Glasgow for a packet of fags and a beer.

 

[bremen nacht]

Welcome to Scotland, Voltaic.

Have you had time to build your bass amp yet?

 

[Wavebourn]

It is not very good idea to take any Hi-Fi amp and use it for a buss guitar. Instrumental amps have to be built with an overdrive in mind, they have to sound musically when overdriven. Hi-Fi amps are most often designed to work without overdrive, and they have low distortion level because of an extra amplification reduced by feedbacks, but when overdriven soud really bad. However, it it was designed to work with 800W of maximal undistorted power, you may use it as a very clean amp on powers of about 40W.

 

[Brett]

It is not very good idea to take any Hi-Fi amp and use it for a buss guitar. Instrumental amps have to be built with an overdrive in mind, they have to sound musically when overdriven. Hi-Fi amps are most often designed to work without overdrive, and they have low distortion level because of an extra amplification reduced by feedbacks, but when overdriven soud really bad. However, it it was designed to work with 800W of maximal undistorted power, you may use it as a very clean amp on powers of about 40W.

For bass guitar, that it utter rubbish. Look at the THD vs power curves of pro power amps* and they look just like hifi amps with a similar level of feedback, ie they're clean to within about 1dB of clipping where they begin to distort rapidly. Many, many, many bass guitarists use pro power amps to supply the power to their rigs and use preamps or effects to provide overdrive or distortion, when and if it's wanted or needed. Most of not all bass guitar rigs out there are predominantly clean, ie minimum distortion generated by the rig itself, unlike guitar, which often uses a huge amount of distortion to get a "tone" required by the music.

You only have to look at bass specific fora like Talkbass to see that there are many bassists that use pre/power amps and the poweramps in these combos are predominantly the same brands/models that drive the FOH. I've been doing this ever since I started playing in the early 80's.

* Examples are Crown, QSC, Yamaha, Quest, Crest etc.

 

[Wavebourn]

What is your point, Brett? Do you mean, you will use 100W transistor Hi-Fi amp instead of 100W bass guitar vacuum tube amp?

 

[Brett]

What is your point, Brett? Do you mean, you will use 100W transistor Hi-Fi amp instead of 100W bass guitar vacuum tube amp?

Who mentioned tubes? That's another whole subject.

You said it couldn't be done with a hifi (ie low measured distortion, high NFB) SS amp of high power, and I stated that it can and is done every day by a large number of bassists, including myself.

Are you speaking from experience, ie do you play, or are you just giving an opinion?