I bought the Line 6 DT-25 112 Combo to complement my POD HD-500 and JTV-69, completing what Line 6 call the Dream Rig. The DT-25 is a valve amplifier which can be dynamically re-wired in a selection of interesting ways.
What makes the Dream Rig worthy of the name is that the POD HD-500 presets can affect the sound of the JTV-69 and the analogue components of the DT-amplifier as well as changing the effects chain in the HD-500. Used in this way, the DT-amplifier’s pre-amp stage is bypassed entirely and that part is modelled by the HD-500. Importantly the valve section is still used so you can get those genuine analoge sounds.
To help you record the output you hear there is a socket labelled Cabinet Simulated Direct Output on the rear of the DT-25. This is a microphone-level sampling the output from the analogue circuitry just before it is fed to the speaker, to which a simulation of the speaker, cabinet and microphone defined in the POD HD preset have been applied.
I bought the DT-25 because I thought it would add something to my recording setup. I am using the S/PDIF from the HD-500 to record the clean tone via my ProFire 610 in case I need to re-amp an unreproducible performance at a later stage in mixing. I thought the Cabinet Simulated Direct Output might sound better than the amp-simulators in the HD-500, and of course it would allow me to put on performances in the future.
There are at least three problems with that idea which I had not appreciated before I bought it:
- If you connect the HD-500 to the DT-25 in the way which allows the POD presets to affect the DT-25 it disables the S/PDIF output on the HD-500.
- Valve amplifiers don’t really do anything sonically interesting until you turn them most of the way up. 25 watts is a lot of loud in your house.
- The Cabinet Simulated Direct Output doesn’t work when the amp is turned up.
The first of these problems is to my knowledge insurmountable, and for me is a deal-breaker.
If you just want to hear yourself play, the second problem can be addressed if you engage low-volume mode, which rescales the volume knob so that it’s a lot quieter at its loudest and digital modelling is used to simulate the valve effects. But if you’re going to digitally model the valve sections you might as well just use the HD-500.
The final problem might be a fault with my unit: I hear what sound a little like digital clipping artifacts even when the output is nowhere near loud enough to be clipped. There is nothing audibly wrong with the sound from the speaker, and the same preset recorded from the HD-500 at max volume without the DT-25 attached is unclipped. It seems likely that the clipping is occurring when the output from the valve stage is sampled so that the speaker and microphone simulation can be applied. Another possibility is that the simulated microphone is being overloaded by the simulated speaker & cabinet leading to simulated excess-SPL artifacts. In the real world I would solve such a problem by moving the microphone further away from the speaker, but since the modelling system doesn’t allow me to deal with it in that way I am assuming that this problem isn’t real.
I think that the clipping-sound might have been worse when I was using my cheapest microphone cable as opposed to a better-quality one: it is difficult to judge because I probably changed other things between tests and if nothing else I had to play it differently because as noted above my usual dry-recording mechanism was disabled when using the DT-25. If that effect was real it might indicate that the problem is magnetic interference inducing a current in an inadequately shielded part of the circuitry. The effect was always present unfortunately, and my better cables are as shielded as microphone cables get, so if it is interference part of the problem is in the CSDO circuitry itself.
These problems mean I will be returning the DT25 for a refund. If I ever get to the point that I want an amplifier for performance purposes with no possible home-studio use I shall certainly consider it or its big brother: the HD-500 preset-driven control is effective and useful. Unfortunately, right now it doesn’t do the thing I wanted it for, breaks something I was using extensively, and costs quite a lot.