Mapletree Audio Design (MAD)

I wanted to leave the subject line general as Mapletree is a small outfit that makes several amps and if anyone has one they can post in this thread.

My particular amp is the Ear+ HDII. I am going to post some specs, which I hope I have copied correctly. Some tube amps seem to have really underwhelming specs, but I guess that is the nature of tubes.

Power at 32 Ohms is 70mW
Frequency Response is 10hz to 20Khz at -1 Db
Gain at 1 kHz via HiZ output is 10DB’s. Approximately 3 Db’s lower at LowZ
Phase structure is non-inverting
Tubes supplied are 2x12B4A (NOS) and 1x12AX7/5751 (new)
Input impedance is 25K Ohms at minimum
Output impedance is 3.5 Ohms
Recommened headphone impedance is 30 to 600 Ohms
Power Consumption is 35 Watts
History is 2002 - 2019 (latest edition)

Here are some pics from the weekend. It is supposed to be finished in a few days.

Pretty excited to try this out.


what’s their website Shane? or who are some of their reseller partners?

They are just a very small operation in Ontario. No resellers. They are at:


grrr…CDN company and advertising in USD. <_<

however, I do love the way they can stack, that’s slick! let’s hope they engineer a DAC that will go with it.

also, which model did you buy? pictures don’t have high enough resolution to zoom in and see.

looks real nice, I’m in the market for a new tube headphone amp, so I will have to look into this.

How much did the ear+ HDII cost you? I don’t see pricing for their headphone amps on the website. @ShaneD

It’s most likely cheaper for CA citizens


As MON said.

Unfortunately, Mapletree is firmly in the territory of analog audio from my research into them. BUT they make Tube buffers for dacs.

that’s too bad…but I get it. I suspect an amp is much easier to make than a DAC.

I wonder what DAC would fit into one of those cases to customize a stack. :wink:

They have a diagram in their user manual

Those two transformes seem to be part of the power supply. Instead of a single transformer with two windings they use two transformers.

I really like the point to point wiring.

Lol probably most of the SMSL dacs

Also anything with a very simple industrial design would work aesthetically. Simple clean lines. Dark Metal.
Go stick wood siding on any Drop Dac and it should fit. Like the airist r2r

They probably can’t buy a readily available transformer with both windings, separate heater transformers are pretty typical. The fact they rectify it to DC is kind of interesting, that and the cathode follower output stage, should make it relatively quiet.

Any Denafrips should also work

It’s a very interesting design, they are using 2 identical transformers. First one to get from 120VAC to 10VAC and then a reversed one to get 240VAC from the 10VAC. It’s a clever way of wiring those transformers. I haven’t seen many tube amplifier diagrams, but the ones I’ve seen use a single transformer with a main winding that gets the high voltage output, and a secondary winding for the tube heaters.


I’ve seen that design before, but I can’t find it now.
I assume they must be dropping the extra 3.7V from the heater supply over the resistor.

By their excellent circuit drawing, the resistor R5 and R6 form essentially a voltage divider. The high power rating (5W or 2W) are important to not starve the tubes of oompf without causing a fire.

Two more pics and my amp is leaving Ontario today. Pretty pumped! :grin:


Nice! These guys have been on my list to eventually get with and have a custom switch box made. Hope you really like your new amp!

You and me both! :laughing:

1 Like