adding HP and EXT speaker jack to Peavey Bandit 112 Teal

[guitardad]

This amp has that weird floating power supply where the rail caps common are part of the speaker load. Flying rail?

I've seen an Envoy schematic with a HP jack, similar circuit, but I can't quite make out the connections. Seems simple enough to do though.

Bandit schematicBandit 112 1989 schematic first one.pdf

[Enzo]

Flying rail (grounded emitter) is not really uncommon, many amps use this configuration. Doesn't really matter to the speaker, just make sure the speaker is not grounded anywhere.

Your link doesn't work, it is one of our dead files.

You can add the Envoy HP circuit exactly as it is in the Envoy. It is a cutout inserted between the speaker and its hot feed. the resistor to ground drops the signal level for the phones. Note it must be an insulated jack. I just use Cliff style jacks and that solves insulation issues. The output hot goes to tip and ring in the jack, the tip and ring cutouts are wired to the speaker hot pin. SImple as that. No phones in jack, circuit routes hot to speaker. Insert phones plug, and the cutouts lift, silencing the speaker. The output signal then flows through the tip and ring to the phones, and the common return flows through the resistor to ground.

The Bandit is designed for an 8 ohm load, Adding an external cabinet in parallel is not recommended. You could wire up a series jack, which would put your external in series with the internal. Two 8 ohm speakers make a 16 ohm load. Or you could easily wire up a jack between amp chassis and speaker to transfer to an external speaker while turning off the internal, that would retain the 8 ohms.

[guitardad]

Flying rail (grounded emitter) is not really uncommon, many amps use this configuration. Doesn't really matter to the speaker, just make sure the speaker is not grounded anywhere.

Your link doesn't work, it is one of our dead files.

You can add the Envoy HP circuit exactly as it is in the Envoy. It is a cutout inserted between the speaker and its hot feed. the resistor to ground drops the signal level for the phones. Note it must be an insulated jack. I just use Cliff style jacks and that solves insulation issues. The output hot goes to tip and ring in the jack, the tip and ring cutouts are wired to the speaker hot pin. SImple as that. No phones in jack, circuit routes hot to speaker. Insert phones plug, and the cutouts lift, silencing the speaker. The output signal then flows through the tip and ring to the phones, and the common return flows through the resistor to ground.

The Bandit is designed for an 8 ohm load, Adding an external cabinet in parallel is not recommended. You could wire up a series jack, which would put your external in series with the internal. Two 8 ohm speakers make a 16 ohm load. Or you could easily wire up a jack between amp chassis and speaker to transfer to an external speaker while turning off the internal, that would retain the 8 ohms.

Awesome thanks!

My concern was not seeing any resistors or other components padding the HP circuit. It's just like using the HP's for a speaker, which was what I saw with the Envoy print.

For the ext speaker, they wanted to add a closed back 1x12. I said I could only do that in series config. I also told them the mfg design was for 8 ohm so that is why there were no ext jacks added.

At first I suggested they use a external speaker to hp unit. They said they did, but didn't like it. I can't imagine a hp sound from this sounding much better than a modeler with cab modeling off.

[Enzo]

The resistor is right at the HP jack. R58 on the Envoy. The full output appears on the HP hot side, but the 150 ohm resistor in the return leg to ground pads the output.

[guitardad]

The resistor is right at the HP jack. R58 on the Envoy. The full output appears on the HP hot side, but the 150 ohm resistor in the return leg to ground pads the output.

Added, working fine, and done!! Sounds ok clean, raspy mess with dist. I started with some K44 headphones then MDR7506.. still kind of bleh, but it works

Thanks so much!

[J M Fahey]

Added, working fine, and done!! Sounds ok clean, raspy mess with dist. I started with some K44 headphones then MDR7506.. still kind of bleh, but it works

Thanks so much!

Thatīs why HP in general are a bad idea in Guitar amps, sound **needs** going through a speaker to be smoothed, otherwise itīs nasty raspy.

As of external speaker, thereīs a third option: add an external speaker jack and a SPDT switch, so the internal amplifier drives either the internal one or the external cabinet ... which must be 8 ohms, or 16 ohms worst case, never 4 ohms.

That way they get the full 80W into the external closed back cabinet.
Sound will be impressive, if said cabinet has at least half decent speakers.

A Bandit driving 4 x 12" speakers can be jaw dropping.

You use a mono cliff type jack, to keep it floating as the original speaker.

You might "save" the switch by relying on jack contacts, but personally I donīt trust them much and to boot, adding a small toggle switch makes the owner realize itīs either internal or external, itīs quite clear they are not in parallel.