HI-FI amplifier for bass guitar

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Hello everyone!

I plan to make an amplifier for my bass guitar (Rickenbacker 4001-1971) 100 to 150 W RMS but I have not found anything suitable yet.
I currently have the woofer and plans for a preamp.
My question is simple:
An amplifier dedicated to HI-FI can he agree or should it be specially designed.
My preference would be to desc mosfet, hexfet, etc ...

Thank you!
 
You can use a Hi Fi designed power amplifier for Bass; the main difference with Home use lies not in sound but in heavy duty use.

A Home amplifier may have 50 or 500W, it's the same, it will normally be used at, say, 5W :( , or "the missus" or neighbours complain, while if you are playing close to a drummer you will *continuously* be using it at 60 to 100W (or more) just to match his acoustic volume.
Drummers play *loud*.
So you'll need an adequate transformer because you *will* be pulling current from it , you'll need good heatsinking, either outside or inside a cabinet with air vents (or a fan) and good short protection, because sh*t happens often.
Instrument amps get moved all the time, connected and disconnected, plugs and jacks are horrible connectors but unfortunately the standard, people steps or trips on them often, etc.
Quite a few Hi Fi amplifier designs offered here, while excellent sounding, have NO, repeat NO short protection :eek:
Nor offer fans, thermal protection, not even a humble bimetallic switch attached to the heatsink .
Fine at Home, maybe also in a *fixed* installation PA/Theater sound/background Music/Church/etc.) but not onstage.

Which, believe it or not, usually are dark, confusing, and sometimes even contain a couple of drunk/stoned people ;)
 
JMFahey thank you for this answer!

Having already played in a band there in a long time, I know all the issues raised.
I do not intend to replay group, I'm too old! :D
I thought about 100 W because I have a speaker that can hold twice that power.
For some time I want to emphasize my old bass guitar and make it sound just for fun.
I've sampled the bass and big sound bank is available free on the internet.

Regards!
 
Guitar amplifiers generally differ from Hi-Fi amps in a number of ways. Of course you can use a Hi-Fi amplifier for guitar use but compare what you will get using the following ideas:-

(This list is not finite and many guys will probably add to it).

1. Stage amps are generally built to be far more robust than home amps.

2. Guitar amps are often built to deliberately add a "flavour" to their sound.

3. Hi-Fi amps are aiming at ZERO distortion, many guitar amps are quite happy with a small amount of distortion.

4. Cost and weight. Not always true I know.

There is nothing to stop you building a Hi-Fi design in a more robust fashion.

5. A guitar has a particular output level which will not match naturally to a Hi-Fi amplifiers input specs.

So YES, with a small pre-amplifier to match the guitar with the amplifier, of course you can use your Hi-Fi.

6. Stage amps are generally Class B or higher to give them more "Bang per Buck". Hi-Fi amps are generally lower power and better quality.

7. Stage amps are generally more robust, both electronically and mechanically. You can drop a stage amp and it probably wont suffer too much. Drop your stereo and it probably wont work afterwards.
 
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5 bis (c'était bien vous qui utilisé une programme de traduction, non?) En plus qu'un préampli HiFi n'est pas réglé pour le niveau d'une instrument (une basse va même un peu fort) il a normalement un impedance d'entrée trop bas (autour de 47k, quand pour une basse j'utilise au moins 1 meg

5. continued (It was you that used a translation program, no?) Not only is the input sensitivity of a Hi-Fi amp not necessarily adapted to instrument level, their input impedance is low, generally around 47kΩ, while with a bass I go for at least 1MΩ

8. Les controls de tonalitie (egaliseurs) d'un ampli hifi sonr assez peu puissant, fait pour compenser les deséquilibres mineurs d'un haut parleur dans une pièce, pendant que dans un ampli pour instrument ils sont beaucoup plus puissant, pour modeller un son.

8. The tone controls (equaliser) for a home HiFi are relatively subtle, for correcting minor imbalances betwee treble an bass for a loudspeaker in a room. Tone controls on an instrument are far more brutal and wider range, as you are building your sound.
 
Okay, you want 100 W and to use mosfets. Search on google diyaudio.com:"Ampeg SVT 3 schematic" and find the repair thread on instruments and amps forum. The schematic diagram is there. You see the Ampeg logo on stacks behind guitar bands on stage on all sorts of television shows. Setting the bias current is allegedly tricky; read all the tips the experienced repairmen say about setting it up after final test.
You want something a little smaller (100w) and safer look up the MJR7 from Michael Renardson.On diyaudio solid state thread I believe, in a thread on output capacitors. It has an output capacitor, which helps keeps shorted speaker plugs from blowing your output transistors and shorted output transistors from blowing your speaker. The MJR7 requires lateral MOSFETS, but maybe it would work with hexfets. It is a simple topology. Huge heatsinks and a fan, nutrix speaker connectors instead of 1/4 phone jacks, It could morph into a guitar amp.
For power supplies you can either buy a toroid transformer from a European source, or try a switching >400w quad voltage power supply from connexelectronic in the diyaudio vendor threads below. If you use a switching supply don't forget to put it in a separate steel box with hash filters (chokes) in and out to prevent RF (radio) leaking into the analog circuits. That is the way Peavey built my CS800s, the power supply in a separate box. (but it is a bipolar transistor amp.)
 
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Well, that bass preamp is designed like an input strip to a console; equaliser in/out switch (on an instrument amplifier? I might have liked an alternative equaliser, to be set up for different numbers) the equaliser itself, modified Baxandall, typical HiFi, input sensitivity (unless you're going to be driving it into distortion) and overload lights… (give them points for the tuner out, though). Being me, I'd put an insert break point and a balanced, ground switchable line out.

With a Rickenbacker you're probably not going to need that ultra high switch (which only works at low volumes anyway; how strange).

While HiFi amps do not generally have to sustain power levels like instrument amps, PA amps or studio monitor amps, they should be able to. If their power supplies sag, or their heat sinks are underrated so they catch fire when you're listening to the 1812 while the neighbour passes the vacuum cleaner they're badly designed. More problematic is that they're not built to be transported all the time; resistors crack off, screws shake loose and rattle around inside, fuses lose contact, and this you can't really criticise them about; even though I might do exactly that when remounting them. Mind you, there have some pretty poorly built guitar amps, too, and some which, when run flat out for any length of time you could cook your hamburger on…
 
Not disagreeing but to put things in perspective:

1) that one is a fine and quite popular Bass preamp, used by many , either self built or supplied in Pedal form by the late Albert Kreuzer.

2) Albert was a Symphonic/Jazz double Bass player,
An externally hosted image should be here but it was not working when we last tested it.

so in that context disabling tone controls and going absolutely "flat" is an option

3) but he also played electric Bass ... not a plain vanilla 4 string of course:
558.jpg

where tone controls are used.

4) he also offered a very well made full amplifier , including his preamp:
An externally hosted image should be here but it was not working when we last tested it.


so, in a nutshell, build that preamp, it's very good :)
 
I have read all your answers and I still have more questions! :p

Preamplifier for my choice is made and it will be that of Albert Kreuzer
Meanwhile I found two patterns that may be suitable amplifier, this is not the mosfet here but should.

http://www.velleman.eu/downloads/0/illustrated/illustrated_assembly_manual_k8060_rev1.pdf

100W Guitar Amplifier (Mk II)

by the late Albert Kreuzer.

I do not know, and luckily I do not have the nose because I failed to send an email to the question about his amplifier.

Thank you all!
 
If their power supplies sag, or their heat sinks are underrated so they catch fire when you're listening to the 1812 while the neighbour passes the vacuum cleaner they're badly designed.

You can't design and build HiFi amps just on the off chance that someone might one to use it for bass guitar.

Engineering HiFi amps to that level would greatly increase their price, and mean no one would buy them - and there's no need for it.

Incidentally, I used to have a Leak Stereo 70 (classic old HiFi amp - used 2x2N3055's per channel) - I used it many times for doing disco's, and it was used for guitar a couple of times.

I also knew a couple of guys who used them full time as guitar amps, and a resident disco that used four or five of them as the complete PA (at a place called Stoke Hall - picture attached - nice!).

You'd struggle as a bass amp though, bass is hard on an amp.
 

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This may be off topic, but I play through a Markbass LittleMark II and its a class D... This amp slams. Have you married yourself to using FETs?

There is a lot of debate on this and that regarding class D, but for bass guitar, its beautiful and the head is small. I use it with a 1x15" cab or a 6x10" and never need to turn past 12 o'clock... I compete with a dimed Marshal JCM900/1960a and a drummer who hits like Bonham on one of Bill Brufords old kits - loud as hell... Headroom is key in a bass rig IMO.
 
You can't design and build HiFi amps just on the off chance that someone might one to use it for bass guitar.

Engineering HiFi amps to that level would greatly increase their price, and mean no one would buy them - and there's no need for it.

Incidentally, I used to have a Leak Stereo 70 (classic old HiFi amp - used 2x2N3055's per channel) - I used it many times for doing disco's, and it was used for guitar a couple of times.

I also knew a couple of guys who used them full time as guitar amps, and a resident disco that used four or five of them as the complete PA (at a place called Stoke Hall - picture attached - nice!).

You'd struggle as a bass amp though, bass is hard on an amp.

I wouldn't; but I would make sure that if someone ran it too loud, too long it might distort, bring in thermal cutouts, go into current limit even blow a fuse, but not do itself any irreparable damage. I hate "peak watts" and "RMS Watts" on transistor gear. You don't even need to worry about power bandwidth on most modern devices.

I used to run a pair of Leak TL12s (valve HiFi amp. more or less a Mullard 5-10) as HF amps in a triamped system; back then they sounded better than anything I could find with transistors, and they really did have peak watts with output transformers.

But I've seen Quads and Pioneer HiFi amps running as studio monitor amps, and there they get as hard hit as instrument amps.

The only reason bass is difficult is that it needs a lot of absolute power relative to, say, a guitar amp. Low frequencies aren't that difficult to amplify, and transistor amps can (though maybe shouldn't) go down to DC. If something tells me it is capable of producing 400 Watts stereo into 4ohms, I don't expect its power supply to drop 15% after 10mS. That's Low Fi.
 
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