Query re connecting Valvetronix amps to PA mixing board

[Voxman]

Hi guys

I know that you can use the line-outs (as in the blue series, which are after the VR circuit & tube)) or the headphone out (all other Valvetronix amps, before the VR circuit & tube) to connect to the PA mixer. But it's been suggested that you can use an extension speaker out (as in the VT50/100) to connect to the board.

My immediate thought is this just sounds 'wrong' & either wouldn't work because the board couldn't cope with the signal, or might even cause potential damage to gear - but I readily admit I just don't know the answer here & would appreciate some expert guidance.

If it is OK, will you get good results, and would you use a speaker or regular guitar cable to make the connection? (obviously you use a speaker cable from amp to another speaker cab - but would it be the same to the mixing board??)

Rich

[jacksback]

I don't know about the external speaker out to a PA mixer. I recall somehow connecting my old 50W Marshall directly into a mixer many years ago, but don't remember exactly how.

However, the bit about the "headphones out" intrigues me. For example, could two VT+ amps be chained by going "headphone out" (guitar into this amp) to "MP3 in" ("slave" amp)? I understand this would circumvent the VR circuit, but would there otherwise be any benefit in doing this, particularly "from" a VT40+ to a VT80+ or VT120+?

[retrobob]

The speaker extension jack is not designed to be a line out, the speaker level is much too high, it will overload the line level input on recorder or PA, with the potential for damage to both pieces of equipment. While it is possible to temporarily get away with doing this using a small solid state amp at very low volume level eventual failure will most likely occur. Use a tube amp this way even temporarily and it could bring a rather quick death to the amp and other equipment.

Speaker levels can be dropped to line level using a direct box rated for speaker levels (safest way), alternatively a method of using a dividing circuit to drop the speaker level to line level can be used, however wire the network incorrectly and damage can occur (not as safe as direct box).

For example, could two VT+ amps be chained by going "headphone out" (guitar into this amp) to "MP3 in" ("slave" amp)? I understand this would circumvent the VR circuit, but would there otherwise be any benefit in doing this, particularly "from" a VT40+ to a VT80+ or VT120+?
Yes you could, but you would achieve no benefit by it. Essentially you would be taking the pre-amp from one amp and feeding it to the power amp of the other, which is what the amp does for itself already.

[Voxman]

Thanks Bob !