how many people have used a maco 300

[hammers]

just wondern how many people have used a maco 300 iv had one and used it 4 5 years now and like it havent blown it up yet hehe any one now what the most you shoud drive em with is and if your yacking away and the tubes start gettin a blue tint to the glow is that a bad thing also am i goin to kill it if im gettin 600 watts out of it how bout some stories and experiances

[721HACKSAW]

I have the mobile version of the Maco 300. You need to keep a close eye on your input wattage and "Tune and Load" it properly. You don't want to have to buy any of those old 8950's they are very expensive.

[Nagant]

Well I've owned, run, and repaired the gray case, green/blue case, chrome case, and the orange face chrome case Maco 300's. The later chrome case jobs are only 5 tube IIRC and the other older models were seven tubers with 2 driving 5. Older ones with good glass would do around 800 to 1100 PEP all out and the later chrome case models would do around 500 to 600 PEP. Of course RMS meter readings will be much lower then PEP.

You can drop the heater voltage from 12 volts to 6 volts to the tube sockets and run the more readily available and less expensive 6LB6. There are many others that will work as well but the 6LB6 is about the least expensive and easiest to find of the 6 volt heater series.

[hammers]

yea mines a 2 drivin 5 box the way i was told to tun and load it was just peak everthing out 4 max output then back off the driver tune a little got a new radio i want to pair up w/it what do u think woud be a safe max to drive it with and if when i been yackin 4 a wile if the tubes start burnin blue is that a sign to let it cool off a while thanx

[Nagant]

They were made in the days of low power radios. If your driving it with the Cobra 85 you list in your user section your fine. I think safely 25 PEP won't have much effect on them. I've driven many with 30-40 PEP for years without issues but it's not the most ideal or safest way as it is beyond the rated input and can cause excess harmonics.

The blue glow is common. I've always wondered why some tubes did it and others don't. I found this explanation of a forum user on a tube board one time:

"the blue glow you refer to is caused by electrons that are accelerated past the tube structure and hits the glass envelope, where it excites impurities in the glass."

[385]

I have a maco 300 and usually drive it with my philly 148. 2.5w dk and 10-12w pep gives me plenty of drive. I tune it for max watts the set the drive knob on the side for about 250w dk and back the load down just a tad and it'll pep around 700-900w. For ssb I re-peak tune and load and back the mic gain down about 1/3 and go with it. I have drove it with 2950 with about the same results. This one that I have is 33 years old with 5 maco 2057 tubes in it that I believe are the original tubes and don't push it much. As far as I know I have no issues with the neighbors and just clean and clear audio.

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[Nagant]

Good looking amp 385.

Those M2057's are so hard to find anymore but the 8950's aren't to bad to come up with for decent prices if one is patient on searching eBay over time.