JDS Atom + ADCOM GTP-500 II Safety of Lab Outputs

[cursive]

Been using the ADCOM GTP-500 II as my preamp / headphone amp for the last 6 years or so, and have been loving it. Great tone controls, great power, and great headphone amp. Only downside is that the amp definitely has some pretty noticeable hiss with more sensitive headphones, though it never hisses with any planars I've paired it with.

After the great writeup of the JDS Atom by Amir, I broke down and purchased the atom. I love the little atom, and it's small footprint, but I still want to use the preamp section of the adcom so I can take advantage of the tone controls etc. On the back of this unit there are two outputs - Normal or Lab outputs. Lab output is considered to be the flattest measuring, most neutral output. In the manual it states the Norm output is capacitance coupled, and the Lab output is direct coupled with no caps at the output. There are some warnings in the manual about using the lab output with certain amplifiers due to the wide band signal, but they never mention headphone amps.

Just wondering if it's safe to use the Lab output (direct coupled) with the JDS atom amplifier. I doubt I would hear a difference between the Norm and Lab outputs, but curiosity has got the best of me, and figured I'd ask.

There's a great article w measurements of the GTP-500 II on Ken Rockwells site for anyone interested @ https://kenrockwell.com/audio/adcom/gtp-500-ii.htm#fr They can be had pretty cheap nowadays.

 

[NTomokawa]

Some amplifiers can't take DC (or something approaching DC) in, otherwise either a protection circuit/relay is tripped, or something is fried.

Amir's review of the Atom shows a frequency sweep perfectly flat down to 10 Hz:

Though honestly your best bet would be to contact JDS labs and ask whether the Atom can handle DC.

Also, though I can't seem to find the input impedance of the Atom, it shouldn't induce any capacitor-based low-frequency rolloff, unless if the output capacitors of the Adcom are abysmally small.

 

[cursive]

Thanks for your thoughts, I'll definitely reach out to JDS Labs to see what they say. If I'm reading the measurements right, it looks like the Adcom preamp is pretty much flat (within .2db) all the way down to .1hz which seems crazy.

I'll update here with the response from JDS Labs just in case anyone else comes across a preamp like this.

 

[NTomokawa]

If I'm reading the measurements right, it looks like the Adcom preamp is pretty much flat (within .2db) all the way down to .1hz which seems crazy.

Technics and/or Pioneer built DC servo amplifiers back in the 80's that could straight-up output DC. I wonder why, because DC easily fries transducers.