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Author Topic: ADA B200s: a couple of questions  (Read 5921 times)

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Iperfungus

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ADA B200s: a couple of questions
« on: Time Format »

So, finally I powered my B200s on and it's a blast!
Very good power amp with tons of punch.

I just have a couple of questions for you, expert guys...

1) when I power my B200s on I can hear a sort of continuous "low level" hum...seems "transfomer's noise"...is this normal/correct? It's not high level noise and it's not disturbing at all while playing...But I can hear it if I stop playing (at home, of course)

2) when I powered it on for the first time, I noticed channel A had very low volume compared to channel B at same setting (channel B had normal volume)...meaning that with pot turned to max channel A had very low volume...and channel B shoot my hair away... I powered the unit off, disconnected and swapped speakers cables, connected them to cab again, powered the unit on...and the issue disappeared...same volume for channel A and channel B at same settings...I did the swap again a couple of times but the issue never arose again...and I played for 2 hours with no other issues. Is this something I should worry about? Did you notice something similar with your B200s? There's something I've to check inside? Or could this have been a bad contact (cable to cab, maybe?)?

Thanks a lot!  :thumb-up:
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rnolan

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Re: ADA B200s: a couple of questions
« Reply #1 on: Time Format »

Hey Max, the very low level hum seems normal, I think it develops a bit over time.  You could nip up the bolts that hold the transformer to the case.

The 2 parts of a B200s that take ware and tare are the vol pots and the speaker output jacks (input jacks tend to stay patched in a rack setup). My guess is it was a slightly dirty output jack that caused your initial issue which cleared with plugging and unplugging.  The vol pots could also use a clean, they can get a bit scratchy over the years. My B200s developed a really bad crackle in one channel (after many years), the tech I took it to couldn't fix it (with 2 attempts)  :facepalm: .  MJMP had had the same issue and fixed it by re-flowing (re-melt) all the solder connections around the power supply. He suggested I just re-flow the whole thing which I did (didn't take long, they are not a complicated amp) and this fixed it  :whoohoo!: :thumb-up: . And while I had it open I gave the vol pots and jacks a good clean/spray. It's worth doing the re-flow just for preventative maintenance if you're up for it.

The output transistors are mounted to the top of the case which gets very hot (this is normal BTW) so make sure there is as much gap between the top and your QV above it as you can.  I used to leave a RU or 2 above it for cooling (although not strictly necessary)
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Iperfungus

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Re: ADA B200s: a couple of questions
« Reply #2 on: Time Format »

Hi Rich!

Thanks for the answers and the tips.
I will check IN and OUT jack connectors on the B200s: I've to pull it out the flight case and clean them with a good spray.
Channel B always work fine, Channel A sometimes starts having "issues" if I disconnect cables...probably IN or OUT jack has some dirt inside.
Today I did a test with mono setup and, at first attempt, Channel A was 100% muted: no sound at all.
Then I disconnected and re-connected cables and it started working again fine with no problems.

By the way...I love it in stereo config!  :banana-guitar:

Pots of both channels are not noisy or scratchy at all, they are smooth all along their stroke and both channels have the same level at each pots setting.

I also like how the B200s works in stereo at 16 ohm: it should deliver 50W+50W and it's perfect with the 80W+80W speakers of the Blackstar cabinet.

As I wrote in my MP-1's thread, I just regret I cannot crank B200s volumes up over 7...  :lol: :lol: :lol:
At the moment I use both channels at 4-5 and I set sound level through MP-1 and GMaj: in this way I can get very good tones even at low volume.

Another thing I've noticed is that my B200s doesn't get hot at all...
I've nailed the MP-1 in flight case's top position, with GMaj between it and the B200s...there's some little space among all the units and air can circulate in a good way through the case, but the GMaj doesn't get hot due to B200s...
Maybe this depends from B200s being used at home levels and underpowered due to 16 ohm impedance of cabinet.

A very good power amp, a very good choice.

Thanks for your suggestions about it, guys!  :thumb-up:
« Last Edit: Time Format by Iperfungus »
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rnolan

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Re: ADA B200s: a couple of questions
« Reply #3 on: Time Format »

Hey Max, pick the right time (when there's no earthquake warning LoL) and take the B200s to 3 o'clock (3/4s) and that's where (or more) to fine tune your sounds/patches. Yeah it will be loud (drummer in the room loud  :whoohoo!: I love drummers BTW) . Hey after that you can turn it down as required... Oh and I suspect your B200s will get a little hotter  >:D .

If you give it 4 ohm load it will give you 124 w p/ch  >:D which is how I used to run my rig (2 x ADA split stacks (cabs are loaded with 8 ohm 90w boogie celestion 12"s  :whoohoo!: ).

Good to hear the pots aren't scratchy  :thumb-up: , many B200s are these days..
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Iperfungus

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Re: ADA B200s: a couple of questions
« Reply #4 on: Time Format »

Update.

Speaking with the guy I bought the B200s from, I discovered that pots were probably scratchy in the past...and he made them "repaired" in some way.
I don't know if pots have been cleaned with some contacts spray or changed with others.
They are not scratchy or noisy for sure now.

By the way, I discovered there's a slight difference between channel A and channel B...they do not sound 100% the same at same level.
Channel B sounds more thick, present, with better bass and high freqs...while Channel A sounds a little "weaker".
I've to investigate this point better...

Do you have any idea, guys?
Should I open a new thread in Power Amps Tech section for this?
Yes, I will.
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Iperfungus

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Re: ADA B200s: a couple of questions
« Reply #5 on: Time Format »

Just to say: I LOVE IT!!!  :thumb-up:
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