Amps that are fan cooled questions

[BogeyBass]

nothing wrong with improving the design but if everything is vented on the back. adding extra venting on sides top or bottom won't benefit cause the amp chassis itself would have to be modified to allow airflow.

it would be amazing though if the amp was 2ohm stable without fans

 

[agedhorse]

I've seen melted laminations on transformers in tube amps.....burned resistors etc

I'm going up call you on the melted transformer laminations comment. That's just impossible, the melting point of grain oriented silicon steel is well over 2000 degrees F. The bobbin and copper would have failed WAY before the steel melted.

Perhaps sticking to factually correct information might help your argument?

 

[bobcruz]

I'm going up call you on the melted transformer laminations comment. That's just impossible, the melting point of grain oriented silicon steel is well over 2000 degrees F. The bobbin and copper would have failed WAY before the steel melted.

Perhaps sticking to factually correct information might help your argument?

Maybe something else melted over the transformer like a cheese sandwich left on top of a vent?

 

[BassmanPaul]

matter of fact I will likely replace the big can caps soon.

Why? Is the amp noisy?

 

[BogeyBass]

not even jet fuel could touch those laminations lol

 

[DavidEdenAria]

I'm going up call you on the melted transformer laminations comment. That's just impossible, the melting point of grain oriented silicon steel is well over 2000 degrees F. The bobbin and copper would have failed WAY before the steel melted.

Perhaps sticking to factually correct information might help your argument?

Sorry, I didn't mean the steel had melted LOL!I am referring to the sticky stuff you see on Vox AC30 transformers which many of us over at the Gear Page have seen pics of for many years.

Is it the paint on the transformer that melts and causes this or some kind of coating?

 

[snarebear]

Other than having a tech check and clean it if needed, I wouldn t modify it. If it doesn t go into protect mode or shut down, I wouldn t worry about it. I assume alot of r&d went into the design to provide maximum airflow to prevent overheating , and if it hasn t yet after all these years and gigs, it most likely will not. I had one for awhile (3-4 yrs), and other than being a nutbuster, was quite reliable.

 

[Thor]

For form's sake I deleted the snarky comments, no need to 'vent' frustrations that way, just move on to another thread that doesn't suffer from misconceptions of basic science.

That being said, let's revisit this conversation...

IIRC, the pair of 10s in the combo is wired for 8 Ohms, which translates to 240 W output. 400 W @ 4 Ohms and 600 W @ 2 Ohms. I'd have to go digging in old paper files to confirm, but that's what I remember.

Back of the amp is showing 960 watt peak at 2 ohms....that's the actual test figure fwiw.

I measured the pair of 2x10 and I then pulled the speakers loose....they measured a bit under what most of my 8 ohm speakers measure but I can't remember exactly.

I don't want to run the stock 2x10 speakers as they are valuable and collectible....only for home practice at lower volumes.

Here's your owners manual btw attached. Your amp is spec'ed out as boughtthefarm mentioned. Actually, the spec is 600W RMS @ 2 ohm. You may be able to produce a transient peak at 900w, but that is not the rating of the amp.
"actual test figure" - Really, according to whom?

You "measured" what exactly on the speakers? Their diameter? Why is that important? Are you seriously considering replacing the speakers that were specifically designed for the cabinet enclosure with some other random speaker? Or are you just going to switch them off and use an extension cabinet instead? That would make more sense should you feel the need to preserve them for posterity.

"don't want to run the stock 2x10 speakers as they are valuable and collectible". What makes these more valuable than any other pair of 16 ohm speakers? Collectible? Not by a long shot except to another Metro owner looking to replace a blown speaker with a used one with the same Thiele-Small parameters.

Anyway, to answer your question, Mr. Nordschow designed the fan to come on at a specific temperature. When is goes on, it is because it is designed to work that way. If you build a box that will encase it in the same manner it is encased now, (and that doesn't obstruct the existing vents), you should have absolutely no problem.

The designer also included the following features for you as a fail safe regarding your trepidation with overheating - as noted on page 3 of the manual:

"thermostatically controlled fan, automatic limiter, a high temperature Auto-limiting system, "

This, of course, is designed to disable your Amp prior to it being reduced to a smoking pile of cinders due to a catastrophic failure of a fan, for example.

Apparently, he seems to have thought of everything already, so unless you can build a better amp design that David Nordschow can, I'd leave the cooling "improvements" the heck alone.

Just my .02, your opinion may vary.

 

[DavidEdenAria]

Why? Is the amp noisy?

No, its not noisy but the electrolytics are now 12 years old plus I am going to run the amp at 2 OHMS.....actually

I don't take chances with my horde of vintage tube amps when it comes to electrolytics.

My tech friend has a capacitor charger so we can remove caps and charge them to see if they are fully functioning.

 

[spaz21387]

My svt has a fan and its always on. I dont think you really have to worry about overheating the amp or anything... my svt has never overheated and its got 11 tubes.

 

[DavidEdenAria]

For form's sake I deleted the snarky comments, no need to 'vent' frustrations that way, just move on to another thread that doesn't suffer from misconceptions of basic science.

That being said, let's revisit this conversation...





Here's your owners manual btw attached. Your amp is spec'ed out as boughtthefarm mentioned. Actually, the spec is 600W RMS @ 2 ohm. You may be able to produce a transient peak at 900w, but that is not the rating of the amp.
"actual test figure" - Really, according to whom?

You "measured" what exactly on the speakers? Their diameter? Why is that important? Are you seriously considering replacing the speakers that were specifically designed for the cabinet enclosure with some other random speaker? Or are you just going to switch them off and use an extension cabinet instead? That would make more sense should you feel the need to preserve them for posterity.

"don't want to run the stock 2x10 speakers as they are valuable and collectible". What makes these more valuable than any other pair of 16 ohm speakers? Collectible? Not by a long shot except to another Metro owner looking to replace a blown speaker with a used one with the same Thiele-Small parameters.

Anyway, to answer your question, Mr. Nordschow designed the fan to come on at a specific temperature. When is goes on, it is because it is designed to work that way. If you build a box that will encase it in the same manner it is encased now, (and that doesn't obstruct the existing vents), you should have absolutely no problem.

The designer also included the following features for you as a fail safe regarding your trepidation with overheating - as noted on page 3 of the manual:

"thermostatically controlled fan, automatic limiter, a high temperature Auto-limiting system, "

This, of course, is designed to disable your Amp prior to it being reduced to a smoking pile of cinders due to a catastrophic failure of a fan, for example.

Apparently, he seems to have thought of everything already, so unless you can build a better amp design that David Nordschow can, I'd leave the cooling "improvements" the heck alone.

Just my .02, your opinion may vary.

To start, "960 watts" is penciled in on the back of the amp from the factory and yes that is peak power.

I measured the resistance of the speakers and they measured lower than similar 16 ohm speakers resistance....no big deal because as I stated I am going to use the stock 2x10 cabinet for at home low volume use only.... likely with other amps.....they sound pretty good with my GK 400 RBIII for example which will be set up in another room.

Unless you folks think this is the wrong thing to do, I plan on running three 8 ohm TL606 EV 15L cabs with the Metro head

Yes, some other Metro owners want these particular stock 10" speakers, and no I am not replacing the speakers in this cabinet.

As I mentioned I have several other bass cabinets I will use, which is part of the reason I am rehousing the amp into a head, so it can easily be moved around.

I AM copying the re-housing design exactly btw.

In one respect, the amp was insufficient from the factory because the stock speaker wire connectors were not making good contact, the connectors seemed sort of cheap and were just dangling.

As I stated, AFAIK, the wire connectors were stock.....I normally do what Leo Fender did and cold crimp & a dab of solder but in this case I installed new spade connectors.

 

[agedhorse]

Sorry, I didn't mean the steel had melted LOL!I am referring to the sticky stuff you see on Vox AC30 transformers which many of us over at the Gear Page have seen pics of for many years.

Is it the paint on the transformer that melts and causes this or some kind of coating?

Usually, that's the tar (or tar-wax or other proprietary material) potting compound that's used to minimize mechanical vibration and fatigue failure of the wire from magneto-constriction. The insides of a transformer are under a lot of mechanical stress from the changing magnetic field. These forces cause the wire to try to move on the core and are (in part) responsible for the vibration that you can sometimes hear from a power transformer. By binding all of the wire together in a potting compound, they can not move and rattle (and ultimately break). There are also winding techniques that can be used to minimize this issue.

 

[DavidEdenAria]

nothing wrong with improving the design but if everything is vented on the back. adding extra venting on sides top or bottom won't benefit cause the amp chassis itself would have to be modified to allow airflow.

it would be amazing though if the amp was 2ohm stable without fans

My svt has a fan and its always on. I dont think you really have to worry about overheating the amp or anything... my svt has never overheated and its got 11 tubes.

Yep, SVT are great designs....like most well designed tube amps they rarely give trouble unless a power tube goes, a bias resistor or cap or an old dried up electrolytic gives up (and hopefully doesn't explode).

 

[DavidEdenAria]

Usually, that's the tar (or tar-wax or other proprietary material) potting compound that's used to minimize mechanical vibration and fatigue failure of the wire from magneto-constriction. The insides of a transformer are under a lot of mechanical stress from the changing magnetic field. These forces cause the wire to try to move on the core and are (in part) responsible for the vibration that you can sometimes hear from a power transformer. By binding all of the wire together in a potting compound, they can not move and rattle (and ultimately break). There are also winding techniques that can be used to minimize this issue.

Thank you sir....I assumed you would have known what I was referring to with "melting transformers" which is a term, however incorrect, widely used at some amp forums....my bad, I apologize.

 

[agedhorse]

No, its not noisy but the electrolytics are now 12 years old plus I am going to run the amp at 2 OHMS.....actually

I don't take chances with my horde of vintage tube amps when it comes to electrolytics.

My tech friend has a capacitor charger so we can remove caps and charge them to see if they are fully functioning.

I would leave the caps alone unless there was a real reason to change them (like measured symptoms of degradation), The lifespan of electrolytic caps under these conditions are several decades. In vintage tube amps, the caps of the 1950's thru 1970's were manufactured with electrolytes and seals that are much different than today's parts. It's standard to use caps with a 85-105 deg C ripple rating, these weren't available in the "good 'ol days". Combine old technology caps with high temperatures and lots of service hours and I would recommend testing them for capacitance and leakage currents under applied voltage.

I see enough gear ruined by well intentioned repairs and upgrades to offer this warning/suggestion.

 

[Rip Van Dan]

The amp is a 2004, made in Minnesota, Eden Metro 2x10 combo one of the last Minnesota Eden built amps.

I am going to rehouse the amp chassis separately as the 2x10 combo is too heavy for me and dig the amp overall a lot.... so, I have no plan to sell the amp as it is a tube and SS preamp that will deliver 900 watts peak into 2 ohms.

The chassis is fully enclosed when inside the 2x10 cabinet.....it is forced fan cooled out the rear of the amp.

Can I get the amp to cool better by modding the new chassis housing (which i will build) somehow so there is better ventilation?

It seems like the amp fan kicks on fairly quickly, especially when I plug in a 2 ohm load which it is designed for btw.

I thought about drilling some vent holes in the side of the new chassis box?

Any suggestions or comments?

If your fan is drawing air in at the fan instead of exhausting it at the fan, you want to open up the chassis, undo the screws that hold it in place; flip it around so it is exhausting air from the fan, not sucking it inside; and then reinstall the screws. Once you get the chassis open it will take you all of about 4 to 5 minutes, if that. Eden made that change many years ago because it gave far better cooling. I'm actually surprised that a 2004 has the fan sucking air in.

The area over the fan went through a number of changes over the years. Originally it was just round holes over the fan. Then it was oval holes. Finally it was one big round hole protected by a wire cage screwed into the back of the cover. I presume yours has the oval holes.

Here's a pic of the fan area opened up and a proctective wire cover over it like it came stock with for the later model WT800B and C models. You can modify yours to match if you like, just be sure the fan exhausts air from the inside and doesn't suck it in:

That will give you better cooling, but don't expect the fan to not be on when you are running it at a 2 ohm load. It will come on and keep running because the amp is generating a lot of heat with a 2 ohm load. You're pushing 620-watts RMS at 2 ohms with the Metro head. Nonetheless flipping the fan around and opening up the fan area will make a significant difference in cooling. You can often replace these fans with quieter versions as long as they have at least the same flow. Curved blade fans from computer stores are a good place to look.

Also, go post this on the Eden owners club thread if you need more specifics on the fan or visit the Eden forum from the Eden site. Odds are they'll give you some specific numbers to look for.

A funny bit of trivia for you: In 2004 Eden made and sold the Metro head separately as well as in the combo. They only did that for a few years. I can send you a 2004 Eden catalog in pdf form if you msg me privately.

 

[DavidEdenAria]

I would leave the caps alone unless there was a real reason to change them (like measured symptoms of degradation), The lifespan of electrolytic caps under these conditions are several decades. In vintage tube amps, the caps of the 1950's thru 1970's were manufactured with electrolytes and seals that are much different than today's parts. It's standard to use caps with a 85-105 deg C ripple rating, these weren't available in the "good 'ol days". Combine old technology caps with high temperatures and lots of service hours and I would recommend testing them for capacitance and leakage currents under applied voltage.

I see enough gear ruined by well intentioned repairs and upgrades to offer this warning/suggestion.

The caps are 12 years old and new ones would be installed by a factory repair tech if need be.

My biggest concern is running the amp at a 2 ohm load...maybe I should stick with a 4 ohm load?

 

[spaz21387]

Yep, SVT are great designs....like most well designed tube amps they rarely give trouble unless a power tube goes, a bias resistor or cap or an old dried up electrolytic gives up (and hopefully doesn't explode).

My svt av is 14 years old and still going on stock tubes. My tech just said shes running strong on the stock sovteks. It tested at 360 watts on the bench. I do want to get a backup set of tubes in the future...

 

[DavidEdenAria]

If your fan is drawing air in at the fan instead of exhausting it at the fan, you want to open up the chassis, undo the screws that hold it in place; flip it around so it is exhausting air from the fan, not sucking it inside; and then reinstall the screws. Once you get the chassis open it will take you all of about 4 to 5 minutes, if that. Eden made that change many years ago because it gave far better cooling. I'm actually surprised that a 2004 has the fan sucking air in.

The area over the fan went through a number of changes over the years. Originally it was just round holes over the fan. Then it was oval holes. Finally it was one big round hole protected by a wire cage screwed into the back of the cover. I presume yours has the oval holes.

Here's a pic of the fan area opened up and a proctective wire cover over it like it came stock with for the later model WT800B and C models. You can modify yours to match if you like, just be sure the fan exhausts air from the inside and doesn't suck it in:

That will give you better cooling, but don't expect the fan to not be on when you are running it at a 2 ohm load. It will come on and keep running because the amp is generating a lot of heat with a 2 ohm load. You're pushing 620-watts RMS at 2 ohms with the Metro head. Nonetheless flipping the fan around and opening up the fan area will make a significant difference in cooling. You can often replace these fans with quieter versions as long as they have at least the same flow. Curved blade fans from computer stores are a good place to look.

Also, go post this on the Eden owners club thread if you need more specifics on the fan or visit the Eden forum from the Eden site. Odds are they'll give you some specific numbers to look for.

A funny bit of trivia for you: In 2004 Eden made and sold the Metro head separately as well as in the combo. They only did that for a few years. I can send you a 2004 Eden catalog in pdf form if you msg me privately.

Thank you VERY much for that info!!

My fan setup is different, it has the fan in the middle with its vents, then on each side of the little heatsink chamber there are 2 more vents.

I assume this is the upgraded design or is this the original Metro fan design?

I was going to mention I read about some Eden amps having revised fan designs but had no actual info or links regarding this.

So YES, apparently there were revisions on some Eden amps in terms of the fan & cooling setup.

Anyone have pics of their Metro fans?

 

[agedhorse]

The caps are 12 years old and new ones would be installed by a factory repair tech if need be.

My biggest concern is running the amp at a 2 ohm load...maybe I should stick with a 4 ohm load?

Won't make any significant difference to the caps. 12 years old is just broken in for a modern cap. If the cap is rated at 85 deg C or greater, I would expect a lifespan of ~20-30 years. Just changing out parts, you run the risk of disturbing something mechanically that you might regret, and there is always the chance of installing a defective new part. Your old caps are proven good performers.