Using 2520 opamps upside down. Premature death?

[Golgoth]

I got a BAE R53 500 series rack.

To my surprise the module connectors in the rack are located at the top of the unit, meaning the modules are sitting "upside down" when installed, in regards of the components location on the pcb. I think the lunchbox was designed for specific BAE modules.

The components in the modules I have installed in the rack are facing down, including the 2520s. I am worried about exhausting my "Studio System Division" and "Melville" 2520s prematurely in that configuration.

What do you guys think? I'm thinking about flipping the rack over to have the modules circuits facing up. Won't be pretty but might help with heat dissipation a bit. Or am I being paranoid and the orientation wouldn't mind that much in such a packed unit as a 500 series module anyway?

Thank you for your insights!

 

[kags]

I would be more concerned about the heat affecting surround components, rather than the opamps themselves. Many units orient the opamps vertically, and they seem to do ok. In API consoles, the opamps are sandwiched between two pcbs and I’ve only had one or two 2520s fail in a 32-channel console over the last 10 or 12 years.

Is the BAE rack vented? I’ve also had several BAE racks’ power supplies fail over the last several years, but the r53 doesn’t require much power for only 3 modules.

 

[Golgoth]

I would be more concerned about the heat affecting surround components, rather than the opamps themselves. Many units orient the opamps vertically, and they seem to do ok. In API consoles, the opamps are sandwiched between two pcbs and I’ve only had one or two 2520s fail in a 32-channel console over the last 10 or 12 years.

Is the BAE rack vented? I’ve also had several BAE racks’ power supplies fail over the last several years, but the r53 doesn’t require much power for only 3 modules.

Interesting! Thanks for the feedback.

The rack is not vented, I would be worried for the internal psu too if using the rack upside down.

 

[Somkereki]

You may think that my habit is excessive, but I usually glue a TO-220 heat sink (Aluminum)) to the IC that gets hot. With silicone rubber adhesive (FBS). It is a good heat conductor and flexible. The hotter an IC gets, the noisier it is and the more likely it is to fail. But even its terminals, if soldered with lead-free solder, are more likely to develop micro cracks. (In the past, the quiescent current consumption of some NE5532s was so high that it was worth cooling them in mic preamp circuits to reduce noise, or in headphone amp circuits to avoid current limits. Many mixing consoles used them in headphone amp circuits. (Max output current 40 to 60 mA) The DIP-8 case has a small surface area for heat dissipation.)I still remember the RCA power transistor catalog published in 1980, which described how many thermal cycles a transistor lifetime has. According to physics, thermal expansion always works!

 

[Eddstudio]

Interesting! Thanks for the feedback.

The rack is not vented, I would be worried for the internal psu too if using the rack upside down.

Hello Golgoth,

Sorry to disturb this thread but I noticed on Reverb.com, that you used to have a Neve vintage 10x2 summing rack.
Did you you sell it?
How did it sound?

I am searching for a summing mixer that could give me that Neve vintage fat and creamy sound.

Thanks for sharing your experience and your reply.
À bientôt j'espère
Regards
Ed

 

[Golgoth]

Hello Golgoth,

Sorry to disturb this thread but I noticed on Reverb.com, that you used to have a Neve vintage 10x2 summing rack.
Did you you sell it?
How did it sound?

I am searching for a summing mixer that could give me that Neve vintage fat and creamy sound.

Thanks for sharing your experience and your reply.
À bientôt j'espère
Regards
Ed

It sounded absolutely gorgeous! They are super hard to come by, I had modded mine to stereo.

x10 T1452s into BA438s summed into a pair of BA283s + LO1166s.

Most likely not that configuration when it left the Neve factory, as they were originally mic preamps into a mono output.

It was a lot of money and not a lot of flexibilty, I sold it (and most of my vintage Neve stuff) to fund other gear.
My current mixer is an API 8200A (with pan, sends, aux, AFL etc..).

Best!
G

 

[k brown]

You may think that my habit is excessive, but I usually glue a TO-220 heat sink (Aluminum)) to the IC that gets hot. With silicone rubber adhesive (FBS). It is a good heat conductor and flexible. The hotter an IC gets, the noisier it is and the more likely it is to fail. But even its terminals, if soldered with lead-free solder, are more likely to develop micro cracks. (In the past, the quiescent current consumption of some NE5532s was so high that it was worth cooling them in mic preamp circuits to reduce noise, or in headphone amp circuits to avoid current limits. Many mixing consoles used them in headphone amp circuits. (Max output current 40 to 60 mA) The DIP-8 case has a small surface area for heat dissipation.)I still remember the RCA power transistor catalog published in 1980, which described how many thermal cycles a transistor lifetime has. According to physics, thermal expansion always works!

That's the first i've heard that silicone adhesive is a good conductor of heat.

Is FBS somehow different from others?

 

[JohnRoberts]

That's the first i've heard that silicone adhesive is a good conductor of heat.

Is FBS somehow different from others?

Its better than air....

JR

 

[Somkereki]

That's the first i've heard that silicone adhesive is a good conductor of heat.

Is FBS somehow different from others?

FBS is supposedly "industrial quality". Although I tried the colorless "saniter" (cheap), it was also excellent. It is a good heat conductor, since nowadays silicone rubber insulating pads are used for power transistors. But the silver thermal paste on my computer's video card always dried up and stopped working. (My sons played on it, both are electrical engineers now ) With the silver paste, the chip temperature was ~90 Celsius, with the silicone rubber it was only ~75 Celsius. (And that's all that's left) I know that silver is a better heat conductor, but liquid silicone rubber can be compressed so that the metal plate of the chip is in contact with the metal surface of the heat sink, and the silicone rubber only fills the small grooves. Silver paste cannot be compressed so thin (think of wet sand). The silicone grease between the silver grains dries out quite quickly, while silicone rubber does not. (I graduated in electronic component and device manufacturing (there wasn't that much math there) and my father and godfather were both chemical engineers, I learned a lot from them too.

 

[k brown]

Pretty sure those heat sink pads are impregnated with heat-condicting material; they're not just sheets of solid silicone.

 

[JohnRoberts]

FBS is supposedly "industrial quality". Although I tried the colorless "saniter" (cheap), it was also excellent. It is a good heat conductor, since nowadays silicone rubber insulating pads are used for power transistors. But the silver thermal paste on my computer's video card always dried up and stopped working. (My sons played on it, both are electrical engineers now ) With the silver paste, the chip temperature was ~90 Celsius, with the silicone rubber it was only ~75 Celsius. (And that's all that's left) I know that silver is a better heat conductor, but liquid silicone rubber can be compressed so that the metal plate of the chip is in contact with the metal surface of the heat sink, and the silicone rubber only fills the small grooves. Silver paste cannot be compressed so thin (think of wet sand). The silicone grease between the silver grains dries out quite quickly, while silicone rubber does not. (I graduated in electronic component and device manufacturing (there wasn't that much math there) and my father and godfather were both chemical engineers, I learned a lot from them too.

When comparing the thermal resistance of various mediums the question is compared to what? Anything is a better conductor than nothing (free air).

Silicone rubber is not even remotely a good thermal conductor unless compared to no heat sink.

JR

 

[Somkereki]

Hello Golgoth,

Sorry to disturb this thread but I noticed on Reverb.com, that you used to have a Neve vintage 10x2 summing rack.
Did you you sell it?
How did it sound?

I am searching for a summing mixer that could give me that Neve vintage fat and creamy sound.

Thanks for sharing your experience and your reply.
À bientôt j'espère
Regards
Ed

An old friend of mine has a very cool recording studio. (Jazz guitarist by the way) He asked me to build him a tube summing amplifier. And to be able to mix from triode to pentode (and a mix of them) (Yes, I'm so old that I still studied vacuum tube circuits in technical school and university. ) It was easier to make good sound back then. If I manage to build it, I will publish the schematic with the measurement results (spectrum picture etc,) The microphone preamplifiers will be Siemens & Halske 811301 units (sinal/noise 132dB !!!) Nice work! I have already "fixed" the Siemens & Halske preamps Almost all the anode-to-grid coupling capacitors leaked! (Made in 1963) I got excellent Polypropylene capacitors. Their insulation resistance is better than 1 TOhm! (yes Tera, 10 to the 12th power) at 300 Volts. (I have a Radiometer IM6 Megohmmeter, the measuring voltage can be adjusted from 1 V to 999 Volts and it measures up to 1000 Terahoms.) I bought it (many years ago) to repair condenser microphones.

 

[Brian Roth]

Pretty sure those heat sink pads are impregnated with heat-condicting material; they're not just sheets of solid silicone.

Since we are on a veer...those silicone pads seem to work in various commercial products I've seen the past few decades.

They sure are "cleaner" than a mica washer and heat sink grease. I know to use nitrile gloves because that grease is tough to get off your fingers.

Bri

 

[Somkereki]

When comparing the thermal resistance of various mediums the question is compared to what? Anything is a better conductor than nothing (free air).

Silicone rubber is not even remotely a good thermal conductor unless compared to no heat sink.

JR

It is indeed far from silver or beryllium oxide (which is toxic), but the point is that the two metal surfaces can come into contact (in the case of video chips) and the silicone rubber only fills the small grooves where there would be air. Mica is not such a good heat conductor, but you can cut a very thin layer out of it. The problem with traditional white aluminum oxide (mixed with silicone grease) thermal paste is that it dries out (more precisely, the silicone grease "creeps out" of it). But if you glue an aluminum heat sink to a DIP-8 case, the case material is some kind of epoxy, but silicone rubber is a better heat conductor ! But the most important thing is the almost zero layer thickness, it only fills the grooves where there would be air! I have been using this method for more than 25 years and measure chip temperatures. On the PC, a utility program displays it on the "tray"

 

[JohnRoberts]

It is indeed far from silver or beryllium oxide (which is toxic), but the point is that the two metal surfaces can come into contact (in the case of video chips) and the silicone rubber only fills the small grooves where there would be air. Mica is not such a good heat conductor, but you can cut a very thin layer out of it. The problem with traditional white aluminum oxide (mixed with silicone grease) thermal paste is that it dries out (more precisely, the silicone grease "creeps out" of it). But if you glue an aluminum heat sink to a DIP-8 case, the case material is some kind of epoxy, but silicone rubber is a better heat conductor ! But the most important thing is the almost zero layer thickness, it only fills the grooves where there would be air! I have been using this method for more than 25 years and measure chip temperatures. On the PC, a utility program displays it on the "tray"

I see your 25 years and raise you. I got a patent for an amplifier heat sink design more than 20 years ago (6,515,859 Roberts , et al. February 4, 2003).

Thermal management involved several thermal resistances in series between device junction and ambient.

Do what works, it's better than free air.

JR

 

[k brown]

It is indeed far from silver or beryllium oxide (which is toxic), but the point is that the two metal surfaces can come into contact (in the case of video chips) and the silicone rubber only fills the small grooves where there would be air. Mica is not such a good heat conductor, but you can cut a very thin layer out of it. The problem with traditional white aluminum oxide (mixed with silicone grease) thermal paste is that it dries out (more precisely, the silicone grease "creeps out" of it). But if you glue an aluminum heat sink to a DIP-8 case, the case material is some kind of epoxy, but silicone rubber is a better heat conductor ! But the most important thing is the almost zero layer thickness, it only fills the grooves where there would be air! I have been using this method for more than 25 years and measure chip temperatures. On the PC, a utility program displays it on the "tray"

Current consensus seems to be that the most effective materials are certain ceramics.

 

[Somkereki]

Pretty sure those heat sink pads are impregnated with heat-condicting material; they're not just sheets of solid silicone.

Yes, it looks like they have some thin, sparsely woven material (maybe Kevlar?) in them to keep their shape. It's very similar to the Kevlar used in the wires of theater microphones. I repaired those a lot in the past, it's an incredibly strong material. I had a special pair of Knipex pliers that I used just for this, because they had to be razor sharp and the two cutting edges had to fit perfectly. And my eyes were better too! When I was young, I went to a shooting club, and at home I practiced with an air rifle on matchsticks from 10 meters. (without rifle scope!) Today I would have a hard time hitting a 100-year-old oak tree! I also use a magnifying headband like the ones used by watchmakers for my work. (We just call it a "horse's eye".)

 

[Somkereki]

I see your 25 years and raise you. I got a patent for an amplifier heat sink design more than 20 years ago (6,515,859 Roberts , et al. February 4, 2003).

Thermal management involved several thermal resistances in series between device junction and ambient.

Do what works, it's better than free air.

JR

Congratulations! Then I can only learn from you about heat sinks. I have dealt with quite a lot of things. My first job was a radio - TV broadcasting station, but I couldn't last half a year, I quit, my head hurt so much when I turned on the 2 FM transmitters at 3:30 in the morning. The FM antennas were low down, 10 - 10 KW- power, the TV dipoles were 40 + 6 KW on a 217 meter high steel tower. After that, I worked with instruments for a few years (TV pattern generators etc). Then a friend of mine invited me to be a sound engineer for a well-known rock band in Hungary. Since then, my favorite thing has been sound engineering. Although I also worked in a plasma physics research laboratory, I even dealt with quantum physics. It's very interesting to think about it that way. We didn't learn anything about it at the technical school and university. You can achieve very interesting results with it in hi-fi and studio technology.

 

[nielsk]

On early 2520s the PCB was orientated so that the components were on the top side (pins facing down), on later units the components were on the bottom of the PCB with taller pins.
No noticeable difference in heat dissipation between them (and the fact that they are potted will likely render this aspect moot)
The choice of output transistors makes a considerable difference in operating temperature.
This component is the culprit in most failures, not the ambient temperature.