Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: John on December 13, 2011, 02:48:26 pm
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http://www.ebay.com/itm/160697936243?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649#ht_500wt_1054 (http://www.ebay.com/itm/160697936243?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649#ht_500wt_1054)
I've been thinking about building a sub box for a while, but pretty sure I can't do it cheaper than this. Question is, is this a good "type" or style box? Don't wanna spend money on something that's not suitable.
I know this is pretty basic stuff, but I've never even put my hands on one so I'm askin'. :smiley:
Thanks!
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You can probably find them cheaper on ebay (for older, or more limited models).
You'll want to google that brand and model to find out the wattage/voltage rating for the device. It may be more limited than you'd expect.
The point is that you could burn out a resistor (or several) by applying amp voltages without thinking/planning ahead. Low resistance values attached to high voltage (B+) supplies yields big current and burned resistors. The ratings may be specified in a way that's not immediately obvious. Find them, and we'll explain.
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That box looks fine and the price is in the ballpark, but for guitar amp work neither 1% precision nor 1 Ohm steps are necessary. Also the housing seems to be plastic. It will be noisy if you run signal through it. Another choice: http://www.parts-express.com/pe/showdetl.cfm?Partnumber=320-076&FTR=RESISTOR%20SUBSTITUTION (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=320-076&FTR=RESISTOR%20SUBSTITUTION)
I bought some old Eico & RCA cap/resistor sub boxes on eBay. I really like them; though some values have drifted. And they're Bakelite with aluminum front panels. So no shielding either unless I add shielding paint or tape internally. They seem to go for anywhere from $10 - $45 so its a crap shoot, but yo can win at a low price eventually.
To run signal outside the amp chassis under test, I use shielded 2-wire mic cable.
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Thank you both! For now I'll just keep looking. That one on Parts Express is more what I had in mind.
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Those two resistors boxes are sold are my local electronic store. IMO they don't have enough resistor and usefull vallue.
I have few vintage resistor substitution boxes at my home shop and I never use them They have never the value I need.
Alligator jumpers and a good stock of separate resitors are the best.
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I have few vintage resistor substitution boxes at my home shop and I never use them They have never the value I need.
What values are they?
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I have few vintage resistor substitution boxes at my home shop and I never use them They have never the value I need.
What values are they?
Why ? Some value on those boxes are usefull but easier and faster for me to take the right resistor from my stock , I have them all .