F5 / Mezmerize Integrated

Hi all,

Here's my latest creation, the F5/Mezmerize integrated amp. I needed something to replace my old but trusty Denon 3802 HTR that would do justice to the Pearl 2 I built a year ago.

6L6 provided a ton of guidance as I worked my way through this four month plus project. I'm thrilled with the result -- it's like listening to my music collection for the first time all over again.

Thanks to DIY Audio for making these boards and case available, and to Nelson for the fantastic designs.

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Very nice !
How did you ground it? I see some cl60 thermistors in the edge?
What kind of potentiometer did you use?
I built a similar F5 without the B1, looks like yours. Will post some pictures also. Is it the 3U chassis also or is it the 4U?
The F5 sounds really good!

I put a #8 screw and locknut through the bottom, ground off the powder coat, and used star-ring terminals to connect safety earth from the PEM, the PS ground through a CL60, and the static shield from the small transformer.

The ground path goes from the Mezmerize signal ground, through both F5s, then to the PS ground, through the CL60, and to earth. The circuit ground on the Pearl 2 floats, so it also follows the same path to earth through the RCAs. It's dead quiet, with the Denon the Pearl was picking up extraneous noise.

I wired the big PS per the build guide with 2 CL60s on a terminal strip from Radio Shack.

The volume pot is an Alps RK27 off of ebay from Hong Kong.

[IMGDEAD]https://dl.dropbox.com/u/370002/IMG_4096.jpg[/IMGDEAD]
 
Is the temperature at the Mezmerize area acceptably low for long life to its electrolytics?

Good question. I'll have to measure it once it's up to full temp, but I think it's OK. There is quite a bit of convection through the case, and the big heat sinks do a great job. I can hold my hand against them for several seconds before it gets uncomfortable. The heat sinks on the Mez mosfets aren't even warm.
 

Salas

diyAudio Chief Moderator
Paid Member
2002-10-08 11:31 am
Athens-Greece
Here is what to roughly expect from elecrolytics and temperature:

"When you will pack it up in its final box measure the temperature on the electrolytics. Rule of thumb is you double half a quoted cap's spec sheet lifespan for each 10 degrees decrement from printed max temp on the cap's sleeve. Example: If you got a 2000 hours 85C electrochemical capacitor working in a 55C environment, then 85C-55C=30C i.e. 3 times 10 degrees less than its max. Half 2000 hours is 1000 hours. 1000*2*2*2=8000 hours. That is how long it will live if the manufacturer is accurate and reliable. "

Quoted from a post I did in the SSA thread once. Of particular interest to all Class A amps builders of course.
 
McQuaide -

Congratulations on a fantastic build!! :) :) :)

Everything looks great! I'm so happy that your project has turned out as good as it did!

Have you decided on adjusting the F5 feedback resistors to get a bit more gain? Or is everything working out well?

Thanks for the nice words, and thanks for answering my never-ending questions.

I'm still deciding on the gain question. Honestly, the gain is plenty for normal listening, especially with a MM (actually MI) cartridge like my Stanton 681ee. No, it's not like a dance club with 110 watts times 5.1 channels from a HTR, but that kind of volume isn't really necessary for serious listening anyway. And as I get older, I think more and more about protecting my hearing.

So I'll give it some time before considering any changes. Plus I want to get out of building, fiddling, hardware store runs, etc and actually enjoy the thing as it is for a while.:D
 
Here is what to roughly expect from elecrolytics and temperature:

"When you will pack it up in its final box measure the temperature on the electrolytics. Rule of thumb is you double half a quoted cap's spec sheet lifespan for each 10 degrees decrement from printed max temp on the cap's sleeve. Example: If you got a 2000 hours 85C electrochemical capacitor working in a 55C environment, then 85C-55C=30C i.e. 3 times 10 degrees less than its max. Half 2000 hours is 1000 hours. 1000*2*2*2=8000 hours. That is how long it will live if the manufacturer is accurate and reliable. "

Quoted from a post I did in the SSA thread once. Of particular interest to all Class A amps builders of course.

Interesting. I have an instant-read food thermometer that will go right down through the top vents and down to the Mezmerize.
 

Salas

diyAudio Chief Moderator
Paid Member
2002-10-08 11:31 am
Athens-Greece
Let it cook for long enough with the lid on. Then remove the lid without powering down and quickly sample main PSU caps, Mez caps, and F5 Mosfets. So the temps can read near to closed box conditions before it cools down a few degrees with lid off. If one's got a DMM with a thermocouple wire probe, it may be fastened on parts of interest passing through a ventilation hole for gathering better temp cycle info.
 
Sure its a big box that dissipates well. Just because we discussed temperature and electrolytics useful life, your class A integrated is a nice example and thank you for checking it out empirically for the topic to be complete.

OK Salas, I played music for a couple of hours with the case closed up, then took some temperature readings in degrees F:

F5 Mosfets: 143.5
Mez PS cap: 93.6
PS cap: 92.6

How does that look?
 
Awesome, this is exactly what I have been planning in my head, but using a second case to house the PSU section for the pre and power sections.

Really nice build!!!

Thanks! I have the Pearl 2 on input 1 and a Panny RP-91 DVD-A player on input 2. Was listening to some Donald Fagen on DVD-A and it sounded tremendous, and with plenty of gain.
 
Sure its a big box that dissipates well. Just because we discussed temperature and electrolytics useful life, your class A integrated is a nice example and thank you for checking it out empirically for the topic to be complete.

Following on from this, I saw in Nelson's article that the heat sinks should run about 25°c above ambient room temperature. 25c=82f, 82+72=154°f. So it looks as though the temp of the F5 mosfets is right in range.

For the caps I just put the probe on the top of the cap until the temp reading stabilized.
 

Salas

diyAudio Chief Moderator
Paid Member
2002-10-08 11:31 am
Athens-Greece
I see some pinkish Mosfet insulation pads in your photos. Are those Keratherm by any chance? Which brings the discussion to the local temperature on the power semis cases is the best criterion. Thermal bonding from semis cases to sinks can vary depending on method and materials.