F5 / Mezmerize Integrated

[Salas]

Originally Posted by McQuaide

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?

143.5=62C i.e very good for this type of Mosfets and 1.3A bias current times their 24V across. ~87C on the silicon die when they can take 150C for short.
Caps at about 93F-94F or 34C on average means 16000 hours for 1000 hour 85C spec or 32000 hours for 2000 hour 85C spec. Again very good. What spec are your caps?

105C caps would be recommended for any hot class A amp inside running over 50C to achieve similar or better if long life electrolyte is used also. Your amp is cool inside and allows you extra choice for lower rated lines that the ''audio'' types usually are.

[McQuaide]

Originally Posted by Salas

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.

I'm using these thermal insulation pads. I couldn't locate mica insulators.

http://www.bergquistcompany.com/ther...0S_12.08_E.pdf

Originally Posted by Salas

143.5=62C i.e very good for this type of Mosfets and 1.3A bias current times their 24V across. ~87C on the silicon die when they can take 150C for short.
Caps at about 93F-94F or 34C on average means 16000 hours for 1000 hour 85C spec or 32000 hours for 2000 hour 85C spec. Again very good. What spec are your caps?

105C caps would be recommended for any hot class A amp inside running over 50C to achieve similar or better if long life electrolyte is used also. Your amp is cool inside and allows you extra choice for lower rated lines that the ''audio'' types usually are.

The caps on the Mesmerize are Nichion KW standard audio, 2000 hours at 85c. On the PS, Panasonic TS-HA, 3000 hours at 105c.

It's good to know it's running cool enough.

[Salas]

The better the pads the hotter the sinks and cooler the power semis. No worries in your case though.
The power PS is gonna have 192000 hours of useful life while your amp is on. Will last you almost like a C-130 Hercules. The Mez caps 32000 hours.

[6L6]

Originally Posted by Salas

. Will last you almost like a C-130 Hercules.

True Story -

One of my professors in college was a squadron commander in the USMC of a C-130 unit in the Vietnam war.

He had a squadron of new C-130, and after flying them around the clock for awhile, the maintainance crews were finding fatigue cracks in the main wing spars. (which will junk the aircraft)

A consultant engineer from Lockheed was brought in to look at the utilization schedule...because these aircraft were new. He looked at things like loading, flight time, mission, flying stresses, etc... (All of which were extremely high, the planes were flying as much a physically possible, almost always departing well above max gross weight, and putting them through a high-stress mission (low level aerial drops, low-level ingress and egress, etc...)

The engineer took all this into account and pronounced these new (about 2yr old) C-130 "done". The continuous high stresses made for a huge multiplication factor on flying time and wear, and they were fatigued and worn out in a fraction of the calendar time that they should have been.

[soldersmoker]

Very cool project and something I was also considering, housing a B1/F5 together. But I think I will use separate boxes, for flexibility's sake. I will be building a Pearl 2 first, as that's a more pressing need right now.

I heard my first F5 a few weeks ago at a friend's place through some big Altecs, and I was VERY impressed. Now, I'm a believer.

[McQuaide]

Pearl2=>B1Mezmerize=>F5 is a highly resolving system. It certainly justifies a high-end source.

[McQuaide]

Salas, would you recommend additional speaker protection with this build? What sort of failure conditions could cause speaker damage from DC?

My speakers are the most expensive components in my system and are pretty much irreplaceable and I want to make sure they're not at risk.

[AndrewT]

The Mesmerize is a DC coupled buffer.
The F5 is a DC coupled amplifier.
Any DC that comes about from a failure in a source, or in the Mez, or in the F5 will be capable of frying the direct coupled drivers in your speakers.
Capacitor coupled drivers should survive.

[6L6]

Andrew - I think he is asking for (if there is) a place that one could add a capacitor to break the DC chain in the signal or something like that.

[AndrewT]

I am confirming his logic in arriving at his question

would you recommend additional speaker protection with this build?

Once he has made a decision he can then look for solutions if he decides he needs such.