Re: Design Failings of the Marntz 8B
- From: RapidRonnie <rapidronnie@xxxxxxxx>
- Date: Wed, 15 Aug 2007 15:10:47 -0700
On Aug 15, 9:23 am, John Byrns <byr...@xxxxxxxxxxxxx> wrote:
In article <13c5ffkf9itn...@xxxxxxxxxxxxxxxxxx>,
Spike <spikeoneNOS...@xxxxxxxxxxx> wrote:
I'm sure this has been gone over many a time.
But for a classis like this it is probably worth it
to discuss it again.
What design "failings"? I have always considered the 8B to have been
Marantz's most perfect creation, unlike the 10B which was a seriously
flawed design.
I agree.
The only "flaw" of the 8B was its unnecessarily complex rotary
switch for metering, which back then made a little more sense. Today a
row of jacks for a DMM makes much more sense, with the appropriate pot
under each. Other than that, and lack of a slow warm up feature of
some sort, the 8B does everything right. If you want to manufacture an
amp that is (aside from the above) easy to troubleshoot and good
sounding and measures well and gives reasonable tube life.....you just
can't go wrong with the 8B.
It does have two feedback sources from two tertiaries on each OPT.
That's a feature I have never seen adequately analyzed. Each 8B is
individually compensated and there is a procedure and I have not seen
it. Former Marantz people are not talking.
Bret says Magnequest says the Marantz output transformers are copied
from Peerless prototypes. Since the Marantz OPTs use square wire in
the secondaries, and no Peerless design does, I question this. If
someone has an 8B handy perhaps they would do us a favor: put a known
voltage on the primaries and tell us the voltages from center to
screen tap and plate connection. Almost all Peerless UL transformers
have 50% taps, because it was possible to series or parallel the half-
primaries for X or 4X the load impedance. In practice it wasn't that
useful a feature, because if one was useful the other wasn't. For
instance the S-265-Q has a 10K :4/8/16, but you can use it as a
2500:same unit also. The problem is that a transformer of that power
handling capability isn't often called for to have a 2500 ohm primary.
(Four tube Fender guitar amps, but they are 120 watt and not 30. )
There's a numbnuts in Massachusetts that is converting McIntosh amps
to 2A3s and such. I heard from someone that bought one used that he
was using the Mc transformer the same way : hooking the primaries in
series and using it as a conventional transformer, so he didn't have
to have two separate centertapped 2.5 filament transformers as in the
MI200.
.
- Follow-Ups:
- Re: Design Failings of the Marntz 8B
- From: Bret Ludwig
- Re: Design Failings of the Marntz 8B
- References:
- Design Failings of the Marntz 8B
- From: Spike
- Re: Design Failings of the Marntz 8B
- From: John Byrns
- Design Failings of the Marntz 8B
- Prev by Date: Re: Design Failings of the Marntz 8B
- Next by Date: Ping Max
- Previous by thread: Re: Design Failings of the Marntz 8B
- Next by thread: Re: Design Failings of the Marntz 8B
- Index(es):
Relevant Pages
|
