Amp thread

[JB RETRO]

Has anyone built a "lamington" valve amp from Valve Heaven, and if so what's it like

[pablopepper]

Has anyone built a "lamington" valve amp from Valve Heaven, and if so what's it like

http://www.buildyourownguitar.com.au...ead.php?t=7370
Maddog is building one right now!

[JB RETRO]

Ok will check it out

[Guvna19]

Researhing Bass Amp questions:

building a JB4-A atm and have no amp or experience with bass's or the amps?

seen a Fender Rumble 30 2nd hand for 100 and gonna check it out.

any feed back on the rumble or other types/brands appreciated.

also, what makes a bass amp so different from a guitar amp?

cheers
Guvna

[Simon Barden]

Quite a few differences between bass amps and guitar amps, though in concept they are quite similar.

1. Bass amps will have different centre band values for their EQ controls. A bass is an octave or more below a guitar, with a low E on a guitar being around 82Hz and low E on bass an octave below that at around 41Hz. So typically, at least the bass and middle EQ controls have a lower frequency centre setting. Often bass amps have an upper and lower mid EQ control.

2. Most bass amps concentrate on clean headroom. Yes some will have drive and/or fuzz options, but most bass amps concentrate on sounding clean until they are very loud. Hence most bass amps are solid state and have large wattage power amps. You can get some high wattage valve bass amps, but they are very heavy as they need a lot of valves and huge output transformers. Whilst they may sound great, you need to be in a band with roadies to take care of all the lifting for you to gig one. A 250W Class D bass amp can now weigh just a couple of kg, so solid state is a much more practical proposition.

3. Almost all bass combos or cabs are tuned enclosures (with the exception of cabs designed for mid- and treble-only frequencies which are often sealed types). Guitar combos and cabs are normally open backed or fully sealed. Speakers aren't very good at reproducing the lower bass frequencies (say less than 60 Hz) at volume. That's fine for guitars with their 82Hz low E, but not for basses. Bigger sized speakers help, but a 2x18" cab isn't going to be very portable. So bass cabs use tuned ported enclosures, where the 'port' (a lengthened connection between the inside of the cab and outside) length and size, is 'tuned' so its resonant frequency boosts the lower bass range of the spectrum, so that the volume of low bass sounds put out by the speaker are amplified because of the port resonance, and so giving a much extended frequency bass sound.

4. The ear is far less sensitive to bass and high frequency sounds than mids. The lower the frequency, the louder it needs to be for it to sound the same volume to the ear as a mid-frequency sound. So in conjunction with tuned cabs, bass amps normally have a basic EQ that boosts the low frequencies more. This takes more amplifier power to do, hence the reason for most bass amps having significantly more power (item 2 above) than a guitar amp. Also why a 30W valve guitar amp can sound louder than a 200W bass amp.


Smaller bass amps (less than 100W) are really for practice only. They have smaller speakers which don't produce a lot of real bass. Which is fine for practice as a lot of bass sound is from the 2nd harmonic, so an octave above the fundamental note but it's never going to make trousers flap.

The Fender is never going to sound wonderful, but for learning bass stuff at home and being portable, it's fine. But it's not going to be loud enough to compete with real drums. Obviously the more you spend, the better sound you can get, even from the smaller bass amps. But for initially learning the bass the Fender will do. But if you stick with bass, then you'd probably soon want something bigger. With a big amp, you can let the amp do all the work and you can play really lightly. With a small amp, you'll need to dig in a lot more to get the volume. Play for too long like that and it becomes hard to change to a different technique.

[Marcel]

There is nothing hard and fast on the "what makes a bass amp so different from a guitar amp?" topic... Many resort to the 'If it sounds good then it's fine' approach, which is fine but sometimes there is a cost...

The basic design of a bass or a guitar amp is essentially the same, although the EQ and response of the two can be vastly different. As a general guide/comment a guitar amp will often have poorer bass response than a bass amp as the frequencies below low E are simply not required, however many bass amps will have treble response that can almost match any regular guitar amp but the EQ controls on a bass amp are often not ideal to set a regular guitars tone.....

Secondly is the OD/distortion aspect. Most guitar amps have this built in to the basic design to various better or worse extents, whereas most bass amps are basically designed to run only clean. A notable of bass amp exceptions is the Orange Crush series of bass combo amps, and there are others.

The big differences are mostly in the EQ circuits and in the actual speaker itself (not the cab, but the noise producing device inside the cab). Both are usually tailored to best suit the frequencies of the instrument that is expected to be played through the amp at what is thought to be the volume levels that the 'rig' will be used at. .

Which leads us to the un-written rule that states - You can run a guitar through a bass amp and often it will work, but usually you can't run a bass through a guitar amp as more often than not the guitar amp just won't cut it... The most common reason a guitar amp will 'fail' is that the speaker cone of a guitar speaker is not designed or built to be capable of delivering bass guitar frequencies at the typically expected volume levels.... There are plenty of YouTube videos out there of guitar speakers tearing themselves to destruction attempting to reproduce bass notes at reasonably high volume levels. At low volumes they'll be fine, crank it up to any extent and you'll be down the shop getting new (expensive) set of drivers fitted to you guitar cab pretty quick.

It's not that bass speaker drivers a better, more it's that each driver be they guitar or bass is designed and built to do a different job and at the typical volume levels to do that job well.

As for the Rumble 30 for 100.... it's probably worth it, even it were for only as a universal clean bedroom practice amp...

[Sonic Mountain]

Hmm thats really interesting. I have an old Ross bass amp from the 70's that is my main 'loud' amp. I've had it forever and it sounds surprisingly awesome. It's one of the first solid state amps from what I can gather. I mostly play straight into the computer these days though so it doesn't get much of a work out. I always get funny looks when I rock up with it, but it really does sound great.

[wazkelly]

$100 is a pretty cheap asking price and probably good place to start for a beginner considering new price is $399. 10" speakers are quite common these days in Bass Amps too. Auxillary input and headphone socket are handy as is the tilt back design so you can aim the speaker where it can be heard rather than just blowing a breeze below your knees.

30W will sound loud enough until you get seriously into playing bass and there are plenty of 50W & 75W combos that will do a good job of keeping up with a drummer and a live stage sound. I bought a 75W Hartke about 18 months ago which is both very heavy and also very loud, and in hindsight the 50W version would have been good enough. Difference was 10" speaker in 50W vs 12" in the 75W which also had a small 7 band eq, all up cost $399 delivered or $299 for the 50W version.

[Simon Barden]

Sonic, I'm pretty sure those Fame series Ross amps were late 80s (86-88). https://www.usedprice.com/items/guit...50-191485.html
I know I bought a small Fame 10 guitar practice amp around that time. It was actually pretty neat with a great fuzzy drive.

Ross was part of the company that made Kustom amps, and Kustom did make some of the first commercial transistor amps on the market. But these Ross amps seem to be an '80s venture, with various amp series being produced from '82-'88, after making the Ross range of FX pedals in the '70s (of which the Ross Compressor is the most famous these days).

[Sonic Mountain]

Yeah cool. It's difficult to find much specific information on them. Style wise the cab looked more retro than that to me, but entirely possible it's 80's.

EDIT:

Confirmed. I could never quite work out what the date on the inspection sticker was, but having that ball park it looks like its says '86 to me. Fun to know.