Maverick TubeMagic D1 Plus — unusually high output impedance?

[northpaw]

I’ve been toying with the idea of getting one of these as it can be used as a preamp as well as an headphone amp, but noticed that Maverick lists the output impedance at the RCAs (Normal or Tube Pre Out) at 5KΩ.

https://www.mav-audio.com/base/product/d1p/hw_d1p

(N.B.: I’m only talking about the RCA outputs, not the headphone out).

That strikes me as unusually high, and potentially problematical if using the D1+ as a preamp with some equipment. Some of my amps have input impedances that are sufficiently high (>50KΩ), but some do not.

Has anyone found the Maverick D1+ picky about what equipment its RCA outs are connected to, when using it as a preamp?

 

[xdd]

Potentially problematic if your cables are high capacitance too - you'll lose HF. Inputs with lower than 50k impedance might be fine - though you'll lose some signal (about 1dB into 50k). To know how well it drives low impedances the maximum linear output current spec needs checking (if they provide such a thing).

 

[E.Man]

I've got one of these.

Can't say I ever noticed anything strange but the impedance isn't something I know about.

I've upgraded opamps and tube too and use a custom amp so I guess I'm not much use

 

[northpaw]

Thanks for the comments, guys. Yes, cable capacitance can be an issue, and I went to all low capacitance cables (15-20pF/ft) a few years ago.

I just thought it was odd that the output impedance was so high for a preamp circuit (and even more so for a well designed DAC circuit, which are often about 100Ω or so, but the D1+ is outputting as a preamp so that probably would not be a fair comparison). Normally I would expect 1KΩ or under for a preamp. Passive preamps can be higher, of course, depending on how the volume pot is wired and the volume setting. I doubt the D1+ is wired as a passive. I did read in one of the other threads here that by setting some internal jumpers the volume pot is bypassed; makes me wonder if the output impedance stays high in that case.

Anyway, the D1+ does get high praise, so it must work well in most situations.

 

[northpaw]

Out of curiosity, I just took a look at the webpages for the Maverick D1 and the D2 units, and they are both listed as having output impedances of only 600Ω, nearly a tenth of what the D1+ is listed at.

The D2 doesn't have a volume control, but the D1 does, although it can be bypassed from the front panel. Perhaps the spec is for the volume pot bypassed, although it does not specify that.

Odd.

 

[automojo]

I have had a D1 plus for a number of years, never had any issue with it being picky. Not sure how you can bypass the volume pot from the front panel, however never used the front line in. It's a great sounding unit. I now use a Grant Fidelity TubeDac-11 in that system (with a NOS Amperex Orange Label) a step up for sure, and more versitle. It also eliminates the step volume pot. I put a Sparko Op amp in the line out position-the GE tube is a great bang for the buck.
I don't hesitate to recommend the D1 plus-it's still a bargain IMHO.

 

[northpaw]

Thanks for these comments.

On the bypass of the volume pot from the front panel: not for the D1 plus, but for the D1 (which was the antecedent in that sentence), via the "Direct" button.

The more I think about it, the more I suspect that the volume pot in the D1 plus is wired in a way that is analogous to that in a passive preamp (I don't know how such a high output impedance would otherwise arise). If so, the D1 plus's output impedance would be variable, depending on the vol setting, meaning a problem with it is unlikely to be encountered unless the volume is set past, say, 12 o'clock. Perhaps that is why no complaints about reduced SQ have cropped up.

If I do go this route, I will have a chance to stack it against an Adcom GDA-700 (much older and no USB, but a great analog section) and a Cambridge DacMagic.