"Bright" -switch in ADA vintage 2x12 cabinets

[AndiK]

As i have recently built some cabinets myself, i would like to know if this switching option 1. is useful? 2. the components ( values for coil and resistor?)
and 3. if this is applicable for celestion g12t-75 also?

i found no info about this switch and it´s effect (but it still could be added)

any info highly appreciated 

Andi

[rnolan]

Hi Andi, welcome to the Depot. I'm not familiar with the switch however, my (limited) understanding of the vintage cabs is they were "browner" sounding and had different speakers (like 30w greenbacks or similar) to sound like the early amps/cabs (Marshalls, Vox, HI Watt etc).  The switch then is probably to give you the best of both worlds (ie adding some brightness to sound like more recent cabs).  If your happy with the sound of your cabs there is probably not much point worrying about it.  Also, once you settle on cabs/speakers the patches you create are relative to them and changing cabs/speakers may require some patch tweaking.  The MP1/MP2 factory presets are designed (tweaked) for various guitar/cab combinations.  My ADA split slant stack cabs have 90w 8 ohm boogie celetions in them.  Like all things boogie they are a bit middy and bright and I had to adjust my patches a bit.
Someone here may have the specs and/or schematics for the vintage cabs which could help inform the discussion.
Cheers Richard

[MarshallJMP]

I have the schematics for this.Shoot me an email and i'll send them to you.

[MarshallJMP]

Here are the schematics

[Sparker]

Thanks MJMP, I was after the inductor details as well.

[MarshallJMP]

I did this "mod" on my ada cabs and i like it.

[Sparker]

What wire gauge/number of turns did you use?

[MarshallJMP]

You mean the inductor?I didn't wind it my self,i just bought one.

[AndiK]

Looks as if the inductor is a more or less simple axial "air" coil - nevertheless it seems a bit hard to find a source for these. A friend will try to build these (he has all the knowledge and testing instruments)....or we find a shop....

Andi

[Windmill]

Here is a photo i took from my ADA 2x12 split stack of the bright switch.



I have a question for you in terms of speakers...
I my ADA cab i have now two CELESTION G12-H100 8 ohms speakers.
I would like to change the exsisting speakers for a Vintage 30 and a G12-T75 to get a different sound.
What do you thing...should i take both of them 8 ohms and wire them like before or are there other options?

[rnolan]

Interesting, I wasn't aware that ADA put G12-H100s in the vintage cabs, my understanding was they use 75 w 12s (G12Ms?) 16 ohm wired in parallel to give 8 ohms.  If the H100s are 8 ohms the box would be 4 ohms (although the bright switch circuit could/may change that ?  MJMP question ?), otherwise it's been modified.
If you put in 2 x 8 ohm speakers, the overall box impedance (depending on bright circuit?) will be 4 ohms (wired in parallel (s1 +ve <> s2 +ve; s1 -ve <> s2 -ve), and either s1 +ve/-ve to jack +/- or s2 +ve/-ve to jack +/-) or 16 ohms (wired in series (jack +ve <> s1 +ve, s1 -ve <> s2 +ve, s2 -ve) <> Jack -ve).  If you put in a 30w and a 75w - the 30 w speaker is probably more sensitive, so louder for the same input (watts) although you risk frying it above 60 w from the amp if the speakers are in parallel (4 ohms), in series (16ohms) they may be ok for 105 watts ??

[MarshallJMP]

The original speakers are 12G50 celestions.These have a better bass response to compensate for the small enclosure.