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Qkizz 29th July 2013 02:27 AM

Martin Logan Summit recap
2 Attachment(s)

Driven by curiosity and success of upgrading caps of my other equipment, time has come to do something with my ML Summit.

Quick look inside revealed two 47uF, yellow ML branded, probably Bennics one Solen 22uF and one 10uF. Panel is crossed at 270Hz.

My previous experiences with Sonicap Gen I were very positive (in and out caps in phono and also in/out caps in tube buffer). SCP were also very useful in bypassing Mundorf silver/Oil output caps in my CJ preamp.

So I took a plunge and replaced original crossover caps: (see pics)

- two yellow 47uF with: 30+30+17+17 *
- 22uF Solen with: 11+11 (had some available)
- 10uF Solen with: 5.1+5.1 (had some available)
* inside cabinet space very,very limited. 17's radius was maximum to be able to fit them on board.


- improved spaciousness and separation
- improved/or not (?see below) stereo imaging
- hear more details though out the freq range
- more dynamics

- Vocals sound "wooden", "boxy", obnoxious and too forward for my liking. They are not as liquid and smooth as they used to be.
- stereo imaging gain depth but width became reduced

This is after 30hours of burn-in time.

Patience is not my middle name and 30h is maybe not enough to draw such conclusions but I remember similar situation with my CJ preamp when I installed Mundorfs Silver/Oil and after bypassing with SCP I was very happy with result.

Therefore I'd like to try bypassing or maybe completely different approach.
If bypassing, what values would be suitable?
Any comments would be much appreciated.

Made my choice of capacitors type and size based on my ZERO crossovers experience so please be understanding.

P.S. Jeff, I owe you some explanation as far as the one SC Gen I 5.1uF. Yes you were right, fault was on my side (close proximity of power cable to unboxed(unshielded) phono preamp. I'll make sure to make it straight with my next order.

Jeff Glowacki 17th August 2013 08:10 AM


My apologies for the very late reply:o

How many hours do you have on them now? Personally, I can not listen to Sonicap for 100 hours. Then they will require 250-350 hours for 100%.

Before making any recommendation, where do the Black, Red, and Green wire go?

Qkizz 21st August 2013 03:36 AM

1 Attachment(s)
Thanks for reply.
Now, after I passed 100h timeline I can totally agree with your statement about "100 hours". Sound just wonderfully opened up. This impression became very consistent from day to day. All of the negatives from my previous post does not apply here anymore.

Changing capacitors to Sonic Cap also cured slight frequency imbalance between speakers, which I thought had different origin.

Green is + goes to step up transformer and to panel
Black is - the same as above
Red goes to Hi Voltage board charging diaphragm/membrane.

This is the best to my knowledge, after analyzing similar crossover schematics from ML Odyssey (attached). Summit model has passive crossover for panel only 270Hz and up.

Qkizz 23rd August 2013 02:50 AM


Originally Posted by Qkizz (
Green is + goes to step up transformer and to panel
Black is - the same as above
Red goes to Hi Voltage board charging diaphragm/membrane.

I think above is not quite right.

It should be:
Red +
Black -
Green goes to hi voltage, bias power supply.

dirmae 13th January 2017 01:31 PM

Hi Qkizz,

Nice job. Do you have the schematics of this crossover?
Any plans of chaning the inductors?


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