Moskido - Hybrid Aikido/MOSFET amplifier

[Kashmire]

Thank you for your output capacitor comments. I appreciate it.

As you can see from my schematics, I'm heavily considering a bipolar PSU for this amplifier build. Also, here's the Pass F4 with a servo loop (schematic below). It's really easy to add the Aikido ... just remove the input FETs and biasing diodes, and hook the Aikido up to the two coupling capacitors.

Both of these candidate circuits are unity-gain push-pull power output stages. I'm planning on using an Aikido to drive it. I will most likely build 2 channels for evaluation, and then a total of 4 channels to passively bi-amp my speakers.

Wonder what your MOSKIDO would sound like without the output capacitor, using a bipolar PSU? That's the big question. Monopoloar or bipolar power supply?

[albertli]

Hi Bob,
Here comes the chassis I finished couple days ago. It is 7 1/4" H, 14" D, 17" W . The fin of heatsink is 2 1/2"

[tubee]

Originally posted by Kashmire
Thank you for your output capacitor comments. I appreciate it.

As you can see from my schematics, I'm heavily considering a bipolar PSU for this amplifier build. Also, here's the Pass F4 with a servo loop (schematic below). It's really easy to add the Aikido ... just remove the input FETs and biasing diodes, and hook the Aikido up to the two coupling capacitors.

Both of these candidate circuits are unity-gain push-pull power output stages. I'm planning on using an Aikido to drive it. I will most likely build 2 channels for evaluation, and then a total of 4 channels to passively bi-amp my speakers.

Wonder what your MOSKIDO would sound like without the output capacitor, using a bipolar PSU? That's the big question. Monopoloar or bipolar power supply?

Without cap is allways better if you ask me. My hybrid has a dc servo too, the only coupling cap used are four 1960's 0.47uF paper in oils to gate of fets. The improvement in sound comparered to a JLH cap coupled SE amp was very obvious. The JHL's collect dust now.

[ilimzn]

Originally posted by albertli
Hi Bob,
Here comes the chassis I finished couple days ago. It is 7 1/4" H, 14" D, 17" W . The fin of heatsink is 2 1/2"

The efficiency of the ehatsinks will be reduced MANY times because they are not vertical. Think about it - warm air wants to go up, and in your configuration, each fin is an obstacle. most of the air will just move along the tops of the fins, the effective area of the ehatsink will be far far lower thanit appears, especially as you have very long fins. You should have cut the heatsinks in half by length and re-oriented the halves so the fins are vertical.

[albertli]

ilimzn,
Thanks for the advice. I did think about that, but I found hard time to cut them into half and still look good. This is why I gave up doing that.
See another pics.

[albertli]

another one without the top plate. You'd find the regulated B+ for Aikido

[beau2317]

The efficiency of the ehatsinks will be reduced MANY times because they are not vertical.

That's what someone said about my case as well. In my case I spent a lot of time finding heatsinks that would fit.

In actual fact the efficiency of the heatsinks is reduced a *bit* but not "many times"

In post #17 of this thread I showed that the thermal capacity of the heatsinks on my amp was reduced from 1.4C/W to 1.54C/W a reduction of about 10%

[jueic]

This Moskido amp is really an excellent one.. I completed mine last week using 2SK1580/2SJ261 as P-P pair,B+ 60V, running only 0.7A.

Comparing with my 300B amp (12ax7 and 12au7 Aikido frontend), this hybrid amp works even better, it has more music details and solid bass. I can hear the 3D music image even from FM jazz broadcasting.

I did a lot of research before building this amp.. my next step for this Moskido will be to try Zen amp topologies with Aikido. This should keep me busy for a while.

[beau2317]

Glad you found the same as we did. My friend had a 300B SE amp with aikido front end and the moskido easily bested it in just about everything (apart from looks!)

You will find it sounds better if you can wind the current up to 1A or more.

Let us know how your experiments go.

[albertli]

jueic,
Happy to know that you have finished yours and happy with it. Could you post some pics.
Albert