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Post subject: 1952 Fender Champion 600 -- Need Advice
Posted: Sun Feb 19, 2012 12:59 pm
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I found a '51-'52 Champion 600 at a thrift store. Originally, the inside of the amp cabinet was lined with thick asbestos insulation. The asbestos insulation has been removed. I read that the asbestos was placed there to protect the cabinet from the heat generated by the vacuum tubes. There was a concern that the wooden cabinet could catch fire. I also read that the metal-can 6SJ7 tube in this amp produces more heat (200-300 degrees F?) than the 12AX7 in the later generation circuits.

My question is this: Do I need to place heat/fire resistant insulation in the cabinet to replace the asbestos?

I own a Champ 600 reissue, and it has no such insulation. However, the inside of the cabinet is painted with some sort of black paint.

I have considered mineral wool acoustic insulation panels in 1 inch thickness, but it is expensive through mail order. I have some yellow polyfill batting from a pair of junked Infinity speakers which could be treated with fire retardant spray, but I am not sure if it would be up to the job.

Any advice from knowledgeable, experienced members of this forum would be greatly appreciated.


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Post subject: Re: 1952 Fender Champion 600 -- Need Advice
Posted: Sun Feb 19, 2012 1:35 pm
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Hi Jaurr, that flame proofing seems unnecessary to me. 200 degrees F would be my guess for top temp on that tube. But I'd try to dig up a 6JS7GT, GTX, or GTY and call it a day. Don't think insulation is suitable. You want as much air space as possible. Maybe run a small fan behind the amp, if you're concerned. JMO. Art

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Post subject: Re: 1952 Fender Champion 600 -- Need Advice
Posted: Sun Feb 19, 2012 3:08 pm
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I've never read anything that indicates Fender used any sort of insulation inside their amps. I don't recall ever seeing a photo of an early Fender amp with insulation in it. Certainly no modern combo or amp head that I am aware of uses insulation and considering that there are a number of high gain amps with 6 or more 12AX7s and 4 or more 6L6GCs in them, those things get pretty hot inside. The key to keeping an amp cool is by maximizing airflow, not lining it with insulation which will only trap the heat where it can have a negative impact on the amp's components.

I bet that the previous owner, not knowing any better installed the insulation. I hope that when it was removed, the insulation was disposed of properly and not just thrown in the trash if it really was asbestos. In any case, I wouldn't worry about it or use a fan as aclempoppi suggested if you are.

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Post subject: Re: 1952 Fender Champion 600 -- Need Advice
Posted: Sun Feb 19, 2012 4:19 pm
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Thank you for the replies. I am knocking myself on the head for not thinking of just using a small desk fan behind the amp. That is what I will do, since my amps just sit in the living room.

I will post a link to a page where I read about asbestos and vintage Fender amps. My Champ is earlier than the one shown and had thick insulation board. I think the asbestos issue is discussed in one of the books about Fender history (Fender: The Shot Heard Around the World or possibly one of the other books).

http://myfenderchamp.com/2009/12/06/twe ... -asbestos/

By the way, with regard to the removal of the asbestos, it was all done safely, properly and in accord with the law.


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Post subject: Re: 1952 Fender Champion 600 -- Need Advice
Posted: Sun Feb 19, 2012 4:53 pm
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jaurr wrote:
Thank you for the replies. I am knocking myself on the head for not thinking of just using a small desk fan behind the amp. That is what I will do, since my amps just sit in the living room.

I will post a link to a page where I read about asbestos and vintage Fender amps. My Champ is earlier than the one shown and had thick insulation board. I think the asbestos issue is discussed in one of the books about Fender history (Fender: The Shot Heard Around the World or possibly one of the other books).

http://myfenderchamp.com/2009/12/06/twe ... -asbestos/

By the way, with regard to the removal of the asbestos, it was all done safely, properly and in accord with the law.


I find the story about using asbestos in the amp to be rather suspicious. Take a look at the chart in this link. It shows the "Auto-Ignition Temperature - or the minimum temperature required to ignite a gas or vapor in air without a spark or flame being present" for various fuels. Notice the ignition point for pine: 800 degrees F :!:

http://www.engineeringtoolbox.com/fuels ... d_171.html

I run two large vacuum tube amps in my home studio, a Fender Blues Deluxe Reissue and a Weber 5F6A Bassman clone that I built. Both have similar tube compliments, one 12AY7, two 12AX7s, and two 6L6GCs. Both are rated at about 40 watts each. Both sit side by side on an old cabinet and are about 1 foot away from tehwall behind them. When I have them both cranking, they nicely warm the room in the winter. The last thing I worry about is either of them going up in flames. :lol:

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Post subject: Re: 1952 Fender Champion 600 -- Need Advice
Posted: Sun Feb 19, 2012 11:27 pm
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bluesky636,

You have made a convincing argument that no insulation was needed in these amps.

Leo Fender had a radio repair shop when he started building guitar amps. Radios from that era had asbestos in them for heat resistance.

http://www.wshu.org/oldradio/collector/hazards.php

Maybe he thought it was a good idea for the amps since radios had it.

In any case, I will just use the desk fan trick if they seem to get too hot.

By the way, do you use a variac (variable transformer) to run your vintage amps at the older household voltage of 110V-117V or just plug them into the wall with modern voltage (120V-130V)?


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Post subject: Re: 1952 Fender Champion 600 -- Need Advice
Posted: Mon Feb 20, 2012 6:49 am
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I wouldn't worry about it. I agree that the amp wouldn't spontaneously combust from the tubes or tranny. With all the amps I've ever owned and tinkered with, I never saw asbestos in them.

I would just look for scorching on the cabinet. That would probably give you the best answer. :wink: Air flow is the key. The reissues have been pretty much molested. Cool little amps, but a bit different from the originals.

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Post subject: Re: 1952 Fender Champion 600 -- Need Advice
Posted: Mon Feb 20, 2012 6:38 pm
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jaurr wrote:
In any case, I will just use the desk fan trick if they seem to get too hot.


I really think that is unnecessary.

jaurr wrote:
By the way, do you use a variac (variable transformer) to run your vintage amps at the older household voltage of 110V-117V or just plug them into the wall with modern voltage (120V-130V)?


None of my amps are vintage. :(

Besides, variacs (autotransformers) are dangerous unless they are properly isolated from the incoming line current.

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Last edited by bluesky636 on Mon Feb 20, 2012 10:22 pm, edited 1 time in total.

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Post subject: Re: 1952 Fender Champion 600 -- Need Advice
Posted: Mon Feb 20, 2012 7:24 pm
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You know Jaurr, I think about that, especially for my '55 Valco. But my old Powerstat variac weighs a ton and I'm kind of lazy. I do keep my eyes on Ebay for more suitable units, but they're pretty expensive. It would probably be a good idea. Any way, my old guy suffers along with a 127VAC wall voltage. So far---no smoke! Art

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Post subject: Re: 1952 Fender Champion 600 -- Need Advice
Posted: Mon Feb 20, 2012 10:24 pm
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aclempoppi wrote:
Any way, my old guy suffers along with a 127VAC wall voltage. So far---no smoke! Art


Wow! Do you live right next door to the power plant? :lol:

My line voltage runs at 121 to 122 V depending on the time of day.

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Post subject: Re: 1952 Fender Champion 600 -- Need Advice
Posted: Tue Feb 21, 2012 12:48 am
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Yeah Bill, We're nuke supplied. Just checked with the Fluke, 122vac. But most of the time it's about 127vac. Don't know, but it bothers me about the old amps. I've been on the look out for a variable regulator. One I can set and rely on for many hours of operation. But so far, the cost is prohibitive. Art

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Post subject: Re: 1952 Fender Champion 600 -- Need Advice
Posted: Tue Feb 21, 2012 5:02 pm
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aclempoppi wrote:
Yeah Bill, We're nuke supplied. Just checked with the Fluke, 122vac. But most of the time it's about 127vac. Don't know, but it bothers me about the old amps. I've been on the look out for a variable regulator. One I can set and rely on for many hours of operation. But so far, the cost is prohibitive. Art


If you use a variac, make sure you use an isolation transformer to isolate it from the incoming line.

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Post subject: Re: 1952 Fender Champion 600 -- Need Advice
Posted: Tue Feb 21, 2012 6:39 pm
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bluesky636,

Why are variacs w/o built-in isolation transformers dangerous? If they are newer versions with properly grounded three-prong cords, wouldn't that help to eliminate much of the danger of a "hot" or "live" metal chassis/enclosure if a short were to occur?

I know there is a danger to the equipment if the voltage is turned-up too high. And, I know the ground wiring on the three-prong cords of the devices and the variac should match and be continuous all the way to the wall outlet. Also, don't most devices (eg. guitar amps) have power transformers which serve to isolate the devices from the incoming voltage from the variac? The only other danger I can think of is the possibility of a power surge. :?

I am not arguing with you. If there is some danger, of which I am not aware, I would like to know. :shock: I am planning to buy a variac for my workbench. I like to be careful around electricity. :idea:


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Post subject: Re: 1952 Fender Champion 600 -- Need Advice
Posted: Tue Feb 21, 2012 7:22 pm
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jaurr wrote:
bluesky636,

Why are variacs w/o built-in isolation transformers dangerous? If they are newer versions with properly grounded three-prong cords, wouldn't that help to eliminate much of the danger of a "hot" or "live" metal chassis/enclosure if a short were to occur?

I know there is a danger to the equipment if the voltage is turned-up too high. And, I know the ground wiring on the three-prong cords of the devices and the variac should match and be continuous all the way to the wall outlet. Also, don't most devices (eg. guitar amps) have power transformers which serve to isolate the devices from the incoming voltage from the variac? The only other danger I can think of is the possibility of a power surge. :?

I am not arguing with you. If there is some danger, of which I am not aware, I would like to know. :shock: I am planning to buy a variac for my workbench. I like to be careful around electricity. :idea:


You are correct. Older variacs without built-in isolation transformers are dangerous for the very fact that there is no isolation between the primary and secondary windings. Just like the old amps of the 50s it is possible to reverse the connections and suddenly have high voltage appear on chassis ground just waiting to grab someone who touches the item connected to the variac and some other grounded object. Modern, isolated variacs would prevent that from happening. Someone buying a used variac off E-Bay, for instance, who doesn't know the difference could end up buying an older style variac without isolation. If you buy from a reputable seller, you should not have that problem. Not everyone has the knowledge or exercises common sense around high voltage.

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Post subject: Re: 1952 Fender Champion 600 -- Need Advice
Posted: Tue Feb 21, 2012 9:34 pm
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Yeah Bill, I do have a 100VA isolation trans. But all that seems too much, except on the bench. If you have any recommendation for a more condensed unit, I'd appreciate it. Art

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