Good news and bad news

whanafi · « **on:** 17 May 2010, 04:22 pm »

My BDA-1 finally arrived just in time to be installed in the rack after having to move house at short notice.

It is connected to a BP26 on the analogue side, and is fed by a Transporter for the digital input, connected by a BNC/BNC SPDIF 75 ohm coax cable.

Also kept the Transporter connected to the BP26 to do a comparison. That's the good news.

The bad news is that my brand new 4BSST2 did a thermal trip on the left channel pretty much by itself. I hadn't had a chance to play any music yet, and was just warming the unit up.

The dealer is saying the unit needs to be "re-biased" which is not something I had heard of before.

Any suggestions? Is this a bad unit? Is re-biasing something expected on a new amp?

Have dug out my old 1992 4B to stick in the place of the unit until it comes back from the shop. Still sounds great as well. Will do some serious comparisons this weekend.

James Tanner · « **Reply #1 on:** 17 May 2010, 04:27 pm »

^^^^^

Hi - bias is adjusted as it leaves the factory and rarely needs readjusting. Disconnect all the inputs and outputs and turn the amp on to see if it still heats us on one side.

james

Napalm · « **Reply #2 on:** 17 May 2010, 04:31 pm »

Quote from: whanafi on 17 May 2010, 04:22 pm

The bad news is that my brand new 4BSST2 did a thermal trip on the left channel pretty much by itself. I hadn't had a chance to play any music yet, and was just warming the unit up.

The dealer is saying the unit needs to be "re-biased" which is not something I had heard of before.

Any suggestions? Is this a bad unit? Is re-biasing something expected on a new amp?

If he's not BS-ing you, I guess he talks about the internal pot that adjusts the "bias" (i.e. current that goes through your power transistors when there's no input signal) has failed and needs replacement/readjustement.

I'm looking forward to hearing the results of your tests.

Nap.

whanafi · « **Reply #3 on:** 17 May 2010, 04:32 pm »

It is back with the dealer, so I can't try any experiments. The unit had tripped while I was listening to relatively low level sound earlier. Since I had torn down the system and re-wired in the new place, all the variables changed with regard to cables. The trip happened without load, other than the physical connections.

Napalm · « **Reply #4 on:** 17 May 2010, 04:33 pm »

Quote from: James Tanner on 17 May 2010, 04:27 pm

^^^^^

Hi - bias is adjusted as it leaves the factory and rarely needs readjusting. Disconnect all the inputs and outputs and turn the amp on to see if it still heats us on one side.

james

Correct. James, are you sure you didn't work for the service dept before?

You may also have some cable issue/loop that creates ultrasonic self-oscillations. You won't hear them but they will heat up the amp.

Nap.

whanafi · « **Reply #5 on:** 17 May 2010, 04:40 pm »

So if it is a cable problem, the trip should switch channels if I swap the speaker cables?

Or could it be interconnects?

I am using XLR interconnects between the 4BSST2 and the BP26. There was a 50/50 chance the same cable was on the left channel.

Napalm · « **Reply #6 on:** 17 May 2010, 04:52 pm »

Quote from: whanafi on 17 May 2010, 04:40 pm

So if it is a cable problem, the trip should switch channels if I swap the speaker cables?

If it's a defective cable, yes. If it's some strange loop that's formed, not necessarily.

You could also have a defective component upstream (CD player or pre) that sends the signal.

So James' advice was the best - try disconnecting all cables first. if it still heats, it's the amp.

Nap.

James Tanner · « **Reply #7 on:** 17 May 2010, 04:54 pm »

Quote from: whanafi on 17 May 2010, 04:40 pm

So if it is a cable problem, the trip should switch channels if I swap the speaker cables?

Or could it be interconnects?

I am using XLR interconnects between the 4BSST2 and the BP26. There was a 50/50 chance the same cable was on the left channel.

Yes if there was a cable problem or a component problem it could cause the amplifier to oscillate and overheat. If you disconnect everything then it eliminates that option and we can look elesewhere for an issue with the amp..

james

whanafi · « **Reply #8 on:** 17 May 2010, 05:03 pm »

I guess the fact that the 4B is handling the same cables and components without a problem is a clue. There are no other components as everything is digital, and there is just a Transporter and BDA-1 feeding the BP26.

Will wait to hear back from the dealer.

James Tanner · « **Reply #9 on:** 17 May 2010, 05:07 pm »

Quote from: whanafi on 17 May 2010, 05:03 pm

I guess the fact that the 4B is handling the same cables and components without a problem is a clue. There are no other components as everything is digital, and there is just a Transporter and BDA-1 feeding the BP26.

Will wait to hear back from the dealer.

Ok that certainly sounds like a 'bias' issue then.

james

werd · « **Reply #10 on:** 17 May 2010, 05:57 pm »

Hello

And just like every other post or Bryston problem we see the unit will be fixed expediently and professionally so it ends up not being bad news at all.....

. Just a small inconvenience that comes with that territory when buying huge power to satisfy your lust for great sound.....

hehe

Napalm · « **Reply #11 on:** 17 May 2010, 06:08 pm »

Quote from: whanafi on 17 May 2010, 05:03 pm

Will wait to hear back from the dealer.

This is a great time to hit the record store and look for some new CDs

Nap.

af · « **Reply #12 on:** 17 May 2010, 06:26 pm »

When my cd dealer see's me coming, he runs and thanks me for my business...I think I am his best customer...buy 6-10 at a time.

whanafi · « **Reply #13 on:** 18 May 2010, 01:35 am »

Quote from: Napalm on 17 May 2010, 06:08 pm

This is a great time to hit the record store and look for some new CDs

Nap.

That would be a great idea if there were any left. The physical stores are down to a local chain called Gramaphone which carries almost nothing released more than 24 months ago (ie. just crap) and HMV which seems to have gone almost entirely video.

There are a few vinyl shops in a specialty mall that has all the high end voodoo cables and stuff, but I don't really have the patience for vinyl - have the collection but not adding to it.

Which leads to a new morality. I WANT to buy music, but the industry won't sell it to me.

Choices are Amazon with shipping costs to Singapore that exceed the value of the CD, HDTracks for downloads but from a limited set of artists (and they exposed my credit card which resulted in it getting hit by fraud and having to be replaced)

or

and this is the situational ethics - getting a FLAC download from a certain bay infested by pirates. It is really sad when the pirate industry has better distribution than the original.

Soo, no new CD's for me. Just sitting here amazed that my 18 year old 4B is handling the KEF's and sounding sweet.

Waleed
(hunkered down in Singapore)

Napalm · « **Reply #14 on:** 18 May 2010, 02:32 am »

Quote from: whanafi on 18 May 2010, 01:35 am

[...]Which leads to a new morality. I WANT to buy music, but the industry won't sell it to me.
Choices are Amazon [...]

Ha! I know the feeling. The big stores don't want to sell us anything but britney spears or so.

The canadian amazon ain't much better, usually when I track down something that I want it's "not in stock" and "available from these sellers" only.

So I learned to do business directly with those sellers. And they have more stuff available than listed on Amazon, so it's worth searching their database directly. For classical music and European imports these two have a large catalog and worked 100% for me:

http://www.grooveyard.ca/

http://www.buycdnow.ca/

Dunno if they would ship to Singapore but I'm mentioning them at least for us suffering Canucks.

Nap.

P.S. If you're after French music, this one in Quebec has stuff too:

http://www.archambault.ca/

P.P.S. Hi-res downloads, classical music, contemporary records:

https://www.analekta.com/

And a CD cover to make sure that I got all your attention:

whanafi · « **Reply #15 on:** 19 May 2010, 04:35 pm »

The news from the amp hospital is positive and apparently the patient has been revived. Will be picking up the 4BSST2 from the dealer on Saturday, so fingers crossed this is the last time it has to leave the rack. The really frustrating part is I have to leave on business, so won't be able to play with the BDA-1 and 4BSST2 combo until I get back in a few weeks.

whanafi · « **Reply #16 on:** 19 May 2010, 04:35 pm »

and it wasn't the cables.

Napalm · « **Reply #17 on:** 19 May 2010, 04:59 pm »

Quote from: whanafi on 19 May 2010, 04:35 pm

[...] The really frustrating part is I have to leave on business, so won't be able to play with the BDA-1 and 4BSST2 combo until I get back in a few weeks.

Call in sick....

Nap.

whanafi · « **Reply #18 on:** 19 Jun 2010, 11:50 pm »

Finally home in Singapore after an epic road trip - Europe on business, attending graduation of daughter at McGill, family time in Vancouver, and conference in Silicon Valley. Suffering from the mother of all jet-lags....

Which means I am up at odd times of the day and have time to play with the equipment.

Re-installed the 4BSST2 into the rack and added some new XLR cables with Neutrik connectors I picked up at Tom Lee in Vancouver. The amp is now behaving itself, and ran for a whole day without overheating or clipping.

Connected the Transporter to the BP26 as an analog connection using XLRs, and to the BDA-1 using a BNC/BNC 75 ohm coax SPDIF cable (which turns out to be a very hard part to acquire).

With those two connections, can now do A/B comparison between the Transporter and BDA-1. It is too early to make a definitive statement - there is an audible difference, but I can't characterize it yet. Need more hours and different music.

What I can say is that both sources do a great job, and the 4BSST2 seems to handle the KEF 205/2 without a problem.

vegasdave · « **Reply #19 on:** 19 Jun 2010, 11:52 pm »

Cool, glad you got everything worked out.