Could my BPT cause my amps to cook?

randog · « **on:** 4 Dec 2003, 04:01 pm »

I bought a BPT-2.0 2nd hand around 6 months ago. Since then I returned an Outlaw receiver to Outlaw to fix a problem with it running too hot (even just as a preamp-only) and I just received my new Odyssey Khartago amp which is running too hot as well. I unplugged it from the BPT and plugged it into the wall and I am checking it now, but I wanted to see if anyone else has experienced these types of problems.

It's never been overloaded and I haven't tried powering the Outlaw through it since I got it back.

Do you think it could be BPT outlet specific? As per BPT, I am using the outlet nearest the cord.

Thanks,
Randog

audiojerry · « **Reply #1 on:** 4 Dec 2003, 04:55 pm »

wow, that's scary. Have you asked BPT if this is possible? Please post how things work out.

tkp · « **Reply #2 on:** 4 Dec 2003, 08:45 pm »

In both of my systems, one with BPT 2.0 ultra and one with BPT 3.5 signiture, the amplifiers ran quite hotter than before. This is not a problem for me because all of my amps are design well with large heat sink to allow the units to push to its limit.

When I first ran accross this, I was a bit puzzled but then I figured out why. The BPT lowered the noise floor of my system coniderably so as a result, I can crank the system at much higher volume without being overwhelm with noise. The end result was that I was listenning to the amps near the top of their wattage rating.

On one occurence, I played the Ampzilla2000 for over three hours near their peak wattage without even knowing about it. My ears were hurt afterward but I did not know it while listening to the system (scary). I have learned from that day to pay attention to the volume level I was listening to to make sure I don't damage my hearing.

randog · « **Reply #3 on:** 4 Dec 2003, 10:14 pm »

Thanks tkp, that's all I needed to know. For both situations, the amps in question do not have external heatsinks. I've had the Khartago on today but plugged into the wall and it still gets hot but not-as-hot yet. Interestingly, it is getting hot without playing music (idle) which is the same issue I had with the Outlaw since I only used it as a preamp. I would like to see if I can find an explanation for that. Anyone?

I think they run hotter through the bpt regardless. Can anyone else with a bpt concur?

Randog

Marbles · « **Reply #4 on:** 4 Dec 2003, 10:38 pm »

Can you check the output voltage of both the wall outlets and the BPT outlets?

My guess is that you have higher than average voltage.

JoshK · « **Reply #5 on:** 4 Dec 2003, 10:43 pm »

Stupid question but how do you check the outputvoltage from the wall without electricuting yourself?

JohnR · « **Reply #6 on:** 4 Dec 2003, 10:44 pm »

I just poke the multimeter leads into the holes... carefully...

JoshK · « **Reply #7 on:** 4 Dec 2003, 10:48 pm »

Thanks John,

I thought about that but I just pictured myself frying holding two pins in the outlet.

ABEX · « **Reply #8 on:** 4 Dec 2003, 11:07 pm »

Yeah,make certain you start at the highest value on the Voltage scale and work your way down to what Line Voltage is.

randog · « **Reply #9 on:** 4 Dec 2003, 11:08 pm »

Quote from: Marbles

Can you check the output voltage of both the wall outlets and the BPT outlets?

My guess is that you have higher than average voltage.

Good'un Marbles.

Who sez customer service is dead? Klaus called me straight away after seeing my post and Chris of BPT emailed me back within an hour or so. Independently, they both suspected the same. I have a friend coming by with a voltmeter and will report my findings. I feel so loved...

Randog

tkp · « **Reply #10 on:** 4 Dec 2003, 11:09 pm »

Randog,

I also measured the input AC and output AC of the BPT. The input voltage is 120 VAC from the wall outlet in my house and the output from the BPT is at 125 VAC with thing idling. It is a common practice to have the secondary to have a bit more winding so that when the transformer inside the BPT has to provide max load current, its output voltage would not drop below the input voltage. This translate into a bit higher voltage rail at the output transistors of the amp so even when idling the amp will likely be a bit hotter when plug into the BPT than plug into the wall.

randog · « **Reply #11 on:** 5 Dec 2003, 01:42 am »

OK, here's the results:

My house voltage is right at 119. The measured voltage through the bpt is -uh-oh - 62 across hot and 62 across neutral. It looks like my bpt has an internal problem. Measuring hot to neutral is 124... similar to your results tkp.

Randog

tkp · « **Reply #12 on:** 5 Dec 2003, 02:00 am »

Quote from: randog

OK, here's the results:

It looks like my bpt has an internal problem.

Randog

You meant there is nothing wrong with you unit

.

Marbles · « **Reply #13 on:** 5 Dec 2003, 02:15 am »

124 is a bit high. I think Klaus normally biases his amps around 120.

I'd give him a call with your numbers.

randog · « **Reply #14 on:** 5 Dec 2003, 02:31 am »

Quote from: tkp

Quote from: randog
OK, here's the results:

It looks like my bpt has an internal problem.

Randog

You meant there is nothing wrong with you unit .

Yes there is! It reads 62 across hot and neutral! It should read 124 across hot and zero across neutral.

bubba966 · « **Reply #15 on:** 5 Dec 2003, 02:35 am »

Quote from: randog

Quote from: tkp
Quote from: randog
OK, here's the results:

It looks like my bpt has an internal problem.

Randog

You meant there is nothing wrong with you unit .

Yes there is! It reads 62 across hot and neutral! It should read 124 across hot and zero across neutral.

No, it's operating exactly how it's supposed to.

From the BPT website

Quote

Balanced AC is a relatively new technology [recognized in the NEC National Electrical Code in 1996] that provides the low-noise power necessary for today's advanced electronics. 120V AC balanced is simple one +60V-to-ground and one
-60V-to-ground. 120V @ 60Hz is available across the circuit, the identical voltage and frequency for which all audio/video equipment power supplies are designed.

randog · « **Reply #16 on:** 5 Dec 2003, 02:57 am »

DOH!

mgalusha · « **Reply #17 on:** 5 Dec 2003, 05:05 am »

I have about 124V on the back of my BPTs as well. I did bias my Odysseys while connected to the BPT, so they are set for that line voltage. They don't run excessively hot.

randog, one of your questions is why they get warm even when idle. It's mainly because of the bias on the output transistors. The bias current keeps them turned on with no signal and allows the amp to run in class A up to a certain power level. This helps prevent crossover distortion and improves the sound. Pure class A amps such as Pass Labs run so hot it's scary and they have massive heat sink capabilties.

Mike G.

doug s. · « **Reply #18 on:** 5 Dec 2003, 05:19 am »

my multimeter also can test temperature - may wanna measure the actual amp temperature to see what the difference really is; the amp mfr should know whether or not it is ok at the higher temp. but in general, higher temps mean shorter life for many elec'l parts.

doug s.

satfrat · « **Reply #19 on:** 5 Dec 2003, 05:56 am »

Randog, I have 2 Butler 3150 amps (3 x 150 watts each), a Sunfire TG3, 2 satellite receivers, a Sony DVD, and a Sony 36XBR400 tv all hooked up to my BP2.5 and my Butlers run lukewarm. Your thread made me run and check them tho. I wish I had a voltmeter as I'd love to take a reading at the Hubbels. I have my Butler's plugged into to first outlets also. I will say your in good hands tho. Both Klaus and especially Chris Hoff have been very good to me. Suggestion Randog, if you end up sending your unit to BPT, have them install a z-sleeve on the output wires. Guaranteed you won't regret it IMHO. The clarity gains are astounding, it's Stillpoints ERS times 10. Regards, Robin