2. amps-preamps
  3. 156499-2546

Who's Gone Topless?

The idea of this goes back decades. Amps and preamps (for the most part) are designed on chassis free breadboards, then voiced, THEN are packaged inside a chassis, which can be the weakest link to hearing what the designer intended. In most cases the chassis sidewalls and bottom are essential, but the top?


First off, beware that doing so will likely affect your mfg warranty, but, if you live in a pet-free, child-free home, then the benefits can more than offset concerns about something getting in that could harm the components. Case in point my Ric Schultz Class D EVS 1200, dual mono IcePower 120as2 modules. HOWEVER, unlike others using the same or similar modules, Ric then sprinkles many decades of modifying pixie dust all around them which are mounted inside an understated (sans bling) Italian sourced chassis.

When I ordered mine it was mandatory to purchase 2 Cubes ($200) which are to be butted up against each board, requiring the owner to remove the top. After doing so, I was anxious to put it in my rack so I could properly isolate it from bad vibes, when I should have listened with and without the Cubes and top.


Ric is also a proponent of weighing down components, but due to the unnecessarily large chassis, it barely fit in my rack, but I had a 5 pound divers belt lead weight that I squeezed in. Now, because RIc chose to put the mute toggles on the back I placed the amp on the first shelf from the rack's top (but out of sight out of mind: I never mute it when done listening), upon which was my CD player/Transport, which I raised up to provide ~ 2" of air space above the top of the 1200 and the bottom shelf of the player. Even though the rack is open on all sides with plenty of air space all around the rack, the amp ran warm

Fast Forward to yesterday. I was listening to Leonard Cohen Essential songs, mostly instrumentally sparse. I removed the weight; and found the music much more open sounding. Encouraged, I FINALLY removed the top. Honestly, I was not prepared for how HUGE doing so could be. It was like the music went from a confined space to an open air 3 dimensional venue. This is so amazing that I am going to get a handle on it via different music before removing the Cubes. Oh, and the amp is now cool as can be. 


So, if interested, stay tuned
tweak1
tweak1 OP
3,738 posts
 
Without responding to anyone directly, but reading through the comments...

* the bass actually has more slam and is more articulate/authentic sounding sans diver weight


* the resultant sound can be likened to previously the microphone/s were wrapped in a towel which muffled the entire 3D soundscape


* From day 1 owning the EVS 1200 I said the chassis is unnecessarily large, (and the lid has no vents)

* The entire chassis is made from the same material, so why would the lid be the big offender

* I am going to get a central air conditioning filter which SHOULD keep dust and mites out while letting hot air escape

* several months ago a friend brought over his laptop which he uses to make live recordings, so it’s not just any old laptop. First we listened through my CD player. When he hit play on his laptop my jaw dropped. After a few notes, I looked at him with jaw dropped.The expression my face said it all, "one giant step" for music playback. BUT, I have 1000+ CDs and am not inclined to transition from them. BUT removing THIS lid brought me a lot closer to the laptop experience

Should go without saying, but YMMV
noromance's avatar
noromance
10,198 posts
 
* The entire chassis is made from the same material, so why would the lid be the big offender
Try removing the entire chassis. See what I did there?
mikelavigne
2,243 posts
 
as far as resonance issues, in addition to the plexiglas sides on my darTZeel NHB-468 mono blocks, the power supply of each amp is suspended inside the chassis. for transport there are screws which get removed and replaced by covers when it’s in place.

i once forgot to remove those transport screws, and i could hear the congestion in the mid range and checked my whole system for something lose or wrong before realizing i had forgot to remove those transport screws.

and if that is not enough for optimization (it’s not, at the tip top of the food chain), both of my mono blocks sit on active Taiko Tana shelves with outboard power supplies.

https://systems.audiogon.com/systems/615

everything does matter.
djones51
4,947 posts
 
Just that, WE DON’T KNOW ANYTHING, for CERTAIN.  
Getting to philosophical for me. 

From day 1 owning the EVS 1200 I said the chassis is unnecessarily large, (and the lid has no vents)

I guess it could have  been running hot.
geoffkait's avatar
geoffkait
23,365 posts
 
In Mapleshade’s Pierre Spray’s “laboratory” downtown DC where I demo’d my Nimbus iso platform back in ‘96 all electronics were sans covers (as we say in the biz). Everything was connected together with those really cool 54 ga interconnects and teeny tiny speaker cables. I distinctly recall we tried just barely damping the top plate of the Nimbus with an Indian silk scarf and it degraded the sound. Just thought I’d mention that. Yes, I said 54 ga.
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