I'm doing up an old guitar 2 x 12 speaker cab, fitted with a 16 Ohm Vintage 30 and a 16 Ohm Alnico Gold. Box is old, drivers are new(ish). I want to switch between 3 settings; 1) to switch the Vintage 30 by itself 2) the Alnico Gold by itself and 3) both speakers running in parallel to the amp. I can put 16 Ohm resistors across the (+ -) of switch in the 'by itself' settings so each setting is a nominal 8 Ohms. Switch Resistors out for both setting. I just want an input jack, wired to a switch, then 2 wires (+ & -) running to each speaker, back to the switch. But trying to figure out how to do it? It's s brain teaser all right. Any switching problem solvers out there?
Do NOT repeat NOT put nominally same value resistors in parallel with Guitar speakers: a sure fire recipe for dull thin sound.
If the different sound flavours are essential, then drive both in parallel from the 8 ohm amplifier out, close mike them individually and mix, mtch and flavour both microphone signals as you wish.
Absolute worst case and if you wantb the direct acoustic sound, no miking: add a relay switch in series with each, and disable one, the other or none, driven from the same 8 ohm tap, the amp will tolerate the 2:1 mismatch with no trouble.
Try to keep it simple; if you add a complex multiple contact switching matrix, the potential for damage is huge .... as in *eventually* running your amp full blast with no load, even if for a fraction of a second, that´s all it takes for a huge spark.
If the different sound flavours are essential, then drive both in parallel from the 8 ohm amplifier out, close mike them individually and mix, mtch and flavour both microphone signals as you wish.
Absolute worst case and if you wantb the direct acoustic sound, no miking: add a relay switch in series with each, and disable one, the other or none, driven from the same 8 ohm tap, the amp will tolerate the 2:1 mismatch with no trouble.
Try to keep it simple; if you add a complex multiple contact switching matrix, the potential for damage is huge .... as in *eventually* running your amp full blast with no load, even if for a fraction of a second, that´s all it takes for a huge spark.
Rightio, Hmmf. Thanx. But Why do the resistors sound thin? I would' ve thought the amp (50 watt Boogie BTW) would be happier, more lively, with the lower impedance? Anyways, I was thinking of a 3-way 4 pole toggle initially. So what form does the relay switch take? Is it rotary, push button ? - sorry my noobness
This question interests me as well.
I can imagine the following effects:
1. Loss of high frequency response, where the speaker starts to look inductive
2. Loss of the speaker's resonant bass peak
3. Less pentode distortion caused by components at those frequencies (larger, less variable arctan(Vp) factor), in addition to whatever high frequency distortion products remain getting attenuated again by #1.
The first two seem very likely. How about the third? Is it significant?
I can imagine the following effects:
1. Loss of high frequency response, where the speaker starts to look inductive
2. Loss of the speaker's resonant bass peak
3. Less pentode distortion caused by components at those frequencies (larger, less variable arctan(Vp) factor), in addition to whatever high frequency distortion products remain getting attenuated again by #1.
The first two seem very likely. How about the third? Is it significant?
What you say is correct, if user decides to use one or another speaker (or both) but as I understand it he wants to switch in the middle of a song, maybe: "I´ll use the Alnico one for rhythm and the Ceramic one for solos" or whatever, back and forth ... there is the distinct possibility of having one switching contact, be it hand switched or relay, where one contact closes *not* in perfect sync with the one which has already opened, mechanical contacts are not instant, have bounce, etc. , besides not only speakers are switched but also transformer taps.
No big deal if you stop between songs and choose one or the other but potentially dangerous *while playing* ; to boot it´s very likely amp will be played loud, distorting.
Personally I wouldn´t risk it.
You can do that safely with SS amps .... but what´s the point of doing so?
No big deal if you stop between songs and choose one or the other but potentially dangerous *while playing* ; to boot it´s very likely amp will be played loud, distorting.
Personally I wouldn´t risk it.
You can do that safely with SS amps .... but what´s the point of doing so?
> a radial cabbone
? ? ?
Ah: Radial Cabbone product from ToneBone. $260.
"the Cabbone actually 'ramps on' the switching process with a timed overlap so that the amplifier always sees a speaker load. ... high-power gold-contact relays to ensure 'straight wire' performance"
? ? ?
Ah: Radial Cabbone product from ToneBone. $260.
"the Cabbone actually 'ramps on' the switching process with a timed overlap so that the amplifier always sees a speaker load. ... high-power gold-contact relays to ensure 'straight wire' performance"
My thinking was to be able to just plug into 1 cab from 8 Ohm jack (from amp, it has 1 x 8 Ohms or 2 x 4 Ohms) and just switch between 3 'flavours' of speaker sound. Either driver or both combined. Not during a verse or chorus or anything like that, more like, what mood I was in. Say rocking out with higher gain tones V30 and then just savouring some cool, clean chords AlnGold. Then at a jam you could just switch to both, whatever was LOUDEST!! You know what I mean? Just making 1 versatile cabinet in the simplest, most elegant way.
If you are willing to make sure the ampis always turned off before you switch your speaker type, you should have no problem at all.
As everyone has explained, the thing to avoid is switching anything on the output of a valve amp while the amp is powered on.
The Radial Cabbone thingy may do what it's supposed to, but it's expensive, and if the switching relay contacts ever fail open-circuit, it will put the amp at risk of frying.
Worth noting: relays, like all electro-mechanical components, are usually much less reliable than semiconductors.
-Gnobuddy
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.