|
|
|
|
| Author |
Message |
Pooh Bear
Guest
|
 Posted: Sat Jun 04, 2005 4:03 am Post subject: Re: Amplifier transistor matching? |
 |
|
Ban wrote:
| Quote: | Joerg wrote:
Hello Graham,
Hmmm.. I'm not specifically into wireless mikes and I think both
the older VHF ( certainly ) and newer UHF ones are good old analogue.
The analog ones are ok, except for a suboptimal squelch and a nasty
pop when muting it. In church you have to do that a lot.
A good place to ask would be alt.audio.pro.live-sound. The issue of
battery life with wireless mikes has come up a good many times.
That's where you'll find ppl who use this stuff all the time. I
don't think you'll avoid 9V batteries though from what I understand.
You might make your 5hrs with rechargeable NiMH but the pros seem to
prefer alkalines - just in case of a bad charge perhaps. The battery
( alkaline ) gets chucked at the end of the gig.
I had asked in rec.audio.pro but I'll try your suggestion tomorrow.
Not today, the barbie is almost ready. Marinated ribs and potatoes
tonight.
We use Ansmann 9V NiMH which seem to be the only ones with 250mAh,
plus nifty uC charge stations. But even with top notch Alkalines our
Sennheiser EW system doesn't reach 5hrs. Actually the Ansmanns hold
out a bit better. Thing is, two AA cells pack a whole lot more energy
than a 9V battery. I wonder why they didn't design for 3V or even
better 2.4V.
Regards, Joerg
But your system sems to be outdated. Here is a 2AA 6-8hrs transmitter
http://www.sennheiser.com/sennheiser/icm.nsf/root/21531
|
You mean ?
http://www.sennheiser.co.uk/uk/icm.nsf/root/21531
Which is an in ear monitoring ( IEM ) *receiver* !
Not the same thing at all !
Graham |
|
| Back to top |
|
 |
|
|
Ban
Guest
|
| Posted: Sat Jun 04, 2005 5:03 am Post subject: Re: Amplifier transistor matching? |
|
|
Pooh Bear wrote:
Sorry, there was still another page in my clipboard, I meant this one (in
German for Joerg)
http://www.sennheiser.com/sennheiser/icm.nsf/root/21405
--
ciao Ban
Bordighera, Italy |
|
| Back to top |
|
|
Pooh Bear
Guest
|
| Posted: Sat Jun 04, 2005 6:01 am Post subject: Re: Amplifier transistor matching? |
|
|
Ban wrote:
Ah - ok - tech spec here.
http://www.sennheiser.co.uk/uk/icm.nsf/root/21405#
Unfortunately not a lapel mic. I wonder if Sennheiser do a simple transmitter
pack ?
Graham |
|
| Back to top |
|
|
Walter Harley
Guest
|
| Posted: Sat Jun 04, 2005 7:02 am Post subject: Re: Amplifier transistor matching? |
|
|
"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:42A0C72A.68DD168@hotmail.com...
| Quote: | Incidentally I can't really see how a failed output device can be
responsible for severe distortion. Normally it's a works or not
situation with output devices.
|
If one of the pair fails, the result is severe distortion - a rectified
waveform, low-pass filtered by the speaker. Only about 30% THD... some
people don't even notice! |
|
| Back to top |
|
|
Walter Harley
Guest
|
| Posted: Sat Jun 04, 2005 7:02 am Post subject: Re: Amplifier transistor matching? |
|
|
"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:d14oe.24267$J12.18509@newssvr14.news.prodigy.com...
| Quote: | BTW, since you seem to be an audio guru: Is there any truly digital
wireless mike system with a reasonable battery life (like >5hrs for the
lapel mikes)? Preferably with AA and not with 9V batteries.
|
Dunno about digital. The Shure analog UHF packs, with lav mics, last more
than 6 hours with a pair of alkaline AAs. One of my gigs uses a dozen or
more channels of them; we put fresh batteries in at 4:30pm, and at 10:30pm
when the show ends they're usually still showing three or four out of five
bars on the battery life indicator. We replace them every night anyway - if
we went for two nights, by the end of the second night we'd be too nervous.
As jak said, the price of batteries is small compared to the price of the
show going down. |
|
| Back to top |
|
|
Pooh Bear
Guest
|
| Posted: Sat Jun 04, 2005 7:02 am Post subject: Re: Amplifier transistor matching? |
|
|
Walter Harley wrote:
| Quote: | "Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:42A0C72A.68DD168@hotmail.com...
Incidentally I can't really see how a failed output device can be
responsible for severe distortion. Normally it's a works or not
situation with output devices.
If one of the pair fails, the result is severe distortion - a rectified
waveform, low-pass filtered by the speaker. Only about 30% THD... some
people don't even notice!
|
Since failure IME is invariably short circuit, I tend to find that it goes
'bang'. Fuse blown etc.
Graham |
|
| Back to top |
|
|
Ban
Guest
|
| Posted: Sat Jun 04, 2005 8:01 am Post subject: Re: Amplifier transistor matching? |
|
|
Pooh Bear wrote:
they also make the SKP100G2 which should be cheaper (no phantom power), but
it is new and not yet in the catalogue. The existing receiver should work
with these too.
--
ciao Ban
Bordighera, Italy |
|
| Back to top |
|
|
Ban
Guest
|
| Posted: Sat Jun 04, 2005 9:02 am Post subject: Re: Amplifier transistor matching? |
|
|
Pooh Bear wrote:
| Quote: | Walter Harley wrote:
"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:42A0C72A.68DD168@hotmail.com...
Incidentally I can't really see how a failed output device can be
responsible for severe distortion. Normally it's a works or not
situation with output devices.
If one of the pair fails, the result is severe distortion - a
rectified waveform, low-pass filtered by the speaker. Only about
30% THD... some people don't even notice!
Since failure IME is invariably short circuit, I tend to find that it
goes 'bang'. Fuse blown etc.
Graham
|
I also have made this experience. Both BJT and FETs go short-circuit and
blow the mains fuse. Maybe in a bridged output configuration it could be a
DC-value, but then the protection kicks in and disconnects the relays.
--
ciao Ban
Bordighera, Italy |
|
| Back to top |
|
|
Pooh Bear
Guest
|
| Posted: Sat Jun 04, 2005 1:02 pm Post subject: Re: Amplifier transistor matching? |
|
|
Ban wrote:
That looks good, although possibly a little chunky to put in one's pocket !
| Quote: | they also make the SKP100G2 which should be cheaper (no phantom power), but it is new and not yet in the
catalogue. The existing receiver should work with these too.
|
I also found this one sold as a 'kit' with a clip on mic - but it's back to 9V batteries.
http://www.sennheiser.co.uk/uk/icm.nsf/root/21101?Open&row=2
Graham |
|
| Back to top |
|
|
Midlant
Guest
|
| Posted: Sat Jun 04, 2005 5:07 pm Post subject: Re: Amplifier transistor matching? |
|
|
Cor, I too have one of these. Is yours a made in California real Marantz
or a later one made in Japan. I have a scratchy right channel. I've
cleaned the pots, especially the volume pot, but it doesn't seem to have
helped. Have you had this problem? If so what did you do to rectify it?
John
"cor" <cor@exchangenet.net> wrote in message
news:42A0CB8B.227EE51F@exchangenet.net...
| Quote: | I am trying to fix an old Marantz 2245 stereo.
one of the amplifier blocks had severe distortion problems.
On inspection, two transistors were suspect. One I can find and fix.
The other transistor is part of two pairs of transistors on
the amplifier block. Apparently these two pairs of transistors
come in matched pairs. One is a 2SC960/LA43 the other one is
a 2SA607/LA43E. Replacement transistors have been reported not
to work satisfactorily on these Marantz circuits.
I was finally able to find 2SC960 transistors but not with the
same LA43 subscript.
My question is, what kind of transistors parameters do you guys
know should be matched among pairs of transistors to see if I got
a suitable matching pair before replacing them. |
|
|
| Back to top |
|
|
Midlant
Guest
|
| Posted: Sat Jun 04, 2005 5:07 pm Post subject: Re: Amplifier transistor matching? |
|
|
My bad. Mine is a Japan model. I have it pulled out as I'm rearranging
the office. In small print under Marantz Sun Valley USA is made in
Japan.
This clears up the incongruity as I thought this series was long after
his USA run.
"Midlant" <washrag71@hotmail.com> wrote in message
news:R0joe.65359$sy6.30149@lakeread04...
| Quote: | Cor, I too have one of these. Is yours a made in California real
Marantz or a later one made in Japan. I have a scratchy right channel.
I've cleaned the pots, especially the volume pot, but it doesn't seem
to have helped. Have you had this problem? If so what did you do to
rectify it?
John
"cor" <cor@exchangenet.net> wrote in message
news:42A0CB8B.227EE51F@exchangenet.net...
I am trying to fix an old Marantz 2245 stereo.
one of the amplifier blocks had severe distortion problems.
On inspection, two transistors were suspect. One I can find and fix.
The other transistor is part of two pairs of transistors on
the amplifier block. Apparently these two pairs of transistors
come in matched pairs. One is a 2SC960/LA43 the other one is
a 2SA607/LA43E. Replacement transistors have been reported not
to work satisfactorily on these Marantz circuits.
I was finally able to find 2SC960 transistors but not with the
same LA43 subscript.
My question is, what kind of transistors parameters do you guys
know should be matched among pairs of transistors to see if I got
a suitable matching pair before replacing them.
|
|
|
| Back to top |
|
|
Joerg
Guest
|
| Posted: Sat Jun 04, 2005 6:03 pm Post subject: Re: Amplifier transistor matching? |
|
|
Hello Graham,
| Quote: | 250mAh is good though. What's the terminal voltage when charged ? If it's only
8.4V that seems to be problematic. I gather some NiMHs have an extra cell.
|
They are seven cell so it is slightly above 9V. Of course it will drop
to 8.4V rapidly but then they stay there almost until exhaustion.
Alkalines show a more steep voltage decline. You can use them down to 6V
and below but the mike's circuitry won't work properly when they are
this low. That is one reason why we changed to NiMH. The other was cost
as 9V alkalines are really expensive. They rarely go on sale like AA
batteries sometimes do.
Regards, Joerg
http://www.analogconsultants.com |
|
| Back to top |
|
|
Joerg
Guest
|
| Posted: Sat Jun 04, 2005 7:02 pm Post subject: Re: Amplifier transistor matching? |
|
|
Hello Ban,
Thanks! This could even work with our existing bank of UHF diversity
receivers. I'll have to find out whether they would operate on NiMH at
2.4V. But even if not, AA batteries are cheap except that this leaves
the environmental concern of disposal.
Regards, Joerg
http://www.analogconsultants.com |
|
| Back to top |
|
|
Joerg
Guest
|
| Posted: Sat Jun 04, 2005 7:02 pm Post subject: Re: Amplifier transistor matching? |
|
|
Hello Graham,
| Quote: | I also found this one sold as a 'kit' with a clip on mic - but it's back to 9V batteries.
|
I really want to discourage our church to buy any more 9V gear. It just
doesn't hold up well enough. But Ban's hint regarding the handheld is
great, too, because we also use handhelds and have the same issues there
(battery quits or just fails). Also, Sennheiser should have no problem
designing a similar transmitter for lapel use. I mean, it's not rocket
science. I have built transmitters that worked off 2.4V decades ago.
They could run for days.
Regards, Joerg
http://www.analogconsultants.com |
|
| Back to top |
|
|
Rich The Newsgroup Wacko
Guest
|
| Posted: Sat Jun 04, 2005 9:02 pm Post subject: Re: Amplifier transistor matching? |
|
|
On Sat, 04 Jun 2005 02:35:05 +0000, Joerg wrote:
| Quote: | Hello Graham,
Hmmm.. I'm not specifically into wireless mikes and I think both the older
VHF ( certainly ) and newer UHF ones are good old analogue.
The analog ones are ok, except for a suboptimal squelch and a nasty pop
when muting it. In church you have to do that a lot.
....
We use Ansmann 9V NiMH which seem to be the only ones with 250mAh, plus
nifty uC charge stations. But even with top notch Alkalines our
Sennheiser EW system doesn't reach 5hrs. ...
|
Five hours??? In CHURCH????!?!?!?!?!?!?!!! =:-O
--
Cheers!
Rich
------
"Hear about... the fellow who was descended from a long line his mother
heard?" |
|
| Back to top |
|
|
|
 FAQ
 Memberlist
 Usergroups
Featured Site: Free Antivirus and Antispyware Info
Powered by p|-|pBB
Usenet and forums posts belong to their respective authors. Everything else is (c) 2004 - 2006 Web-S-Sense Pty. Ltd.
Terms and Conditions of Use
|
|
|
Search
Register
Log in to check your private messages
Profile
Log in
