MXL 603S Schematics?

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Hi!

Anyone have a line on schemos for this mic? Already replaced the 2N5401
& 5551 xstrs and got an improvement in top end. Would like to do
further upgrades, mainly caps. Thanks!

Regards,
Joe
 
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Joe Kramer <musetrap@earthlink.net> wrote:
>
>Anyone have a line on schemos for this mic? Already replaced the 2N5401
> & 5551 xstrs and got an improvement in top end. Would like to do
>further upgrades, mainly caps. Thanks!

My basic feeling is that until that transformer goes you really don't need
to bother with anything else.

You should be able to draw the schematic out in an hour or so.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
 
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Funny, all mine are xformerless.

Scott Dorsey wrote:
> Joe Kramer <musetrap@earthlink.net> wrote:
> >
> >Anyone have a line on schemos for this mic? Already replaced the 2N5401
> > & 5551 xstrs and got an improvement in top end. Would like to do
> >further upgrades, mainly caps. Thanks!
>
> My basic feeling is that until that transformer goes you really don't need
> to bother with anything else.
>
> You should be able to draw the schematic out in an hour or so.
> --scott
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."
 
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The pair of 5401's comprise the balancing circuit transistors. The
5551 shouldn't really have any noticeable impact on the sound as it
really only serves as a buffer following the FET at the input.

I'm not sure which FET is used in the 603, but there's no really
worthwhile advantage to swapping the FET in the virtually identical 990
series (which uses a 2SK170). If it isn't already, you could perhaps
swap the FET at the input to a 2SK170 BL, but doing so may require
rebiasing with the trim pot...so I really don't recommend doing it
unless you feel up to the added headache...

The most effective cap swap you can make is swapping the DC blocking
cap connected across the two posts on the back of the circuit board
right at the capsule for a 1000pf polystyrene or styroflex cap.

Honestly, the easiest way to upgrade a 603 is to sell it and get a 991.
It uses the same circuit, an upgraded board that uses traces instead
of jumper wire, and capsule, but has incorporated many of the proposed
upgrades found on various DIY forums already.

Remember to clean up the board and give it a good spray of sealant to
prevent moisture poblems, and be careful, some of the traces on these
things are very delicate.

Cheers,
Chris

BTW, for more than you ever wanted to know about modding the 603, take
a look around this forum:
http://www.prodigy-pro.com/forum/
 
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Scott Dorsey wrote:
> Chris Cavell <chriscavell@cavellstudios.com> wrote:
> >Funny, all mine are xformerless.
>
> The 603? These are the little front-address pencil mikes with the
> Feilo design?
> --scott
>
>
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

Yep. Here's a link to some pics if you want 'em (found in a
GIS)...pretty much identical in just about ever way to the 99x series
from MXL except for upgraded componentry (unless they've changed
something recently):
http://www.digital-synthologie.de/mxl603s/
 
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What did you swap those transistors out with?
I might want to try this mod myself, any other details?



"Joe Kramer" <musetrap@earthlink.net> wrote in message
news:xRple.874$MI4.448@newsread2.news.pas.earthlink.net...
> Hi!
>
> Anyone have a line on schemos for this mic? Already replaced the 2N5401
> & 5551 xstrs and got an improvement in top end. Would like to do
> further upgrades, mainly caps. Thanks!
>
> Regards,
> Joe
 
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Chris Cavell <chriscavell@cavellstudios.com> wrote:
>Funny, all mine are xformerless.

The 603? These are the little front-address pencil mikes with the
Feilo design?
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."
 
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They have a bit of a "honk" to them that can make tonal full range
instruments, like piano, really ugly on specific notes. Swapping out
several of the caps (all ceramic) to film or styrene tends to cure this
for the most part. BTW, the 990 and 991 are identical...the 990 just
has a rather nifty mounting scheme for the small di capsule to make it
side adress (and appear like a large di to anyone who doesn't look
carefully). The circuits are identical and use the exact same
componentry, but the number designations on the circuit boards change
from one model to the next.

Unofficial means that he basically doesn't want to catch any "gruff" if
their are errors...it's basically the standard schoeps circuit.
 
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I've had the issue (on all my 603's and 991's...at first I thought it
was a problem with a single mic so I swapped them about) on three
different steinways (9 foot new york D, 7 foot new york B, and a 7.5
foot Hamburg C). Perhaps the differences in what we've noticed has
more to do with mic techniques with these particular mics. In all the
instances where I noticed an issue I was micing very very closely
(within a foot of the strings, just inside the crook of the piano).

Roger W. Norman wrote:
> I don't have a clue as to what you're talking about. My 603s have been on
> maybe 100 Steinway recordings without a single honk. Now Mike Rivers did
> seem to sense some noise at one point on a different setup, but I believe it
> was the Soundcraft, for certainly nothing has been untoward on my Crest, and
> like I said, 100 recordings don't lie.
>
> But I guess some people just HAVE to change things. Until I get proof that
> these mics need something different, I'll just keep using them as I have and
> enjoy the results. I do have examples.
>
> --
>
>
> Roger W. Norman
> SirMusic Studio
> http://blogs.salon.com/0004478/
> "Chris Cavell" <chriscavell@cavellstudios.com> wrote in message
> news:1117237355.304415.196030@g43g2000cwa.googlegroups.com...
> > They have a bit of a "honk" to them that can make tonal full range
> > instruments, like piano, really ugly on specific notes. Swapping out
> > several of the caps (all ceramic) to film or styrene tends to cure this
> > for the most part. BTW, the 990 and 991 are identical...the 990 just
> > has a rather nifty mounting scheme for the small di capsule to make it
> > side adress (and appear like a large di to anyone who doesn't look
> > carefully). The circuits are identical and use the exact same
> > componentry, but the number designations on the circuit boards change
> > from one model to the next.
> >
> > Unofficial means that he basically doesn't want to catch any "gruff" if
> > their are errors...it's basically the standard schoeps circuit.
> >
 
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Hey Chris!

Thanks so much for the link! That schemo looks pretty darn close!

Joe
 
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In article <1117217592.566764.182400@z14g2000cwz.googlegroups.com> chriscavell@cavellstudios.com writes:

> Digging a bit I think I may have found you a schematic:
> http://www.omnipressor.com/MicSchLib/MXL603S.jpg

I guess "unofficial" means that someone traced out the board and made
the drawing. It doesn't look complicated enough so that any
significant errors are likely, but I didn't check it.

I recently picked up a 991 (with the 990, which I probalby don't have
much use for) because I wanted an example of a cheap condenser mic and
I was pleasantly surprised with its performance, at least in a
relatively non-critical application.



--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
 
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Chris Cavell wrote:
> The pair of 5401's comprise the balancing circuit transistors. The
> 5551 shouldn't really have any noticeable impact on the sound as it
> really only serves as a buffer following the FET at the input.

Right. I replaced the 5401's with 2N5087, and the 5551 with MPSA18. I
did and A/B with an unmodded mic and noticed a little more "air" with
the modded one. To be honest, I don't understand what the 5551 is doing
in the circuit. MPSA18 has a lower NF though, so I figured it couldn't
hurt. . . .

> I'm not sure which FET is used in the 603, but there's no really
> worthwhile advantage to swapping the FET in the virtually identical 990
> series (which uses a 2SK170). If it isn't already, you could perhaps
> swap the FET at the input to a 2SK170 BL, but doing so may require
> rebiasing with the trim pot...so I really don't recommend doing it
> unless you feel up to the added headache...

Both mine contain 2SK170. I have 2SK117 on hand, but probably wouldn't
be a big difference.

> The most effective cap swap you can make is swapping the DC blocking
> cap connected across the two posts on the back of the circuit board
> right at the capsule for a 1000pf polystyrene or styroflex cap.

Right. I was also looking at the .22 ceramics. The WIMAs shown on the
other link you gave me will probably do it--thanks again!

> Honestly, the easiest way to upgrade a 603 is to sell it and get a 991.
> It uses the same circuit, an upgraded board that uses traces instead
> of jumper wire, and capsule, but has incorporated many of the proposed
> upgrades found on various DIY forums already.

Thanks for the info on the 991. But I already have the 603s, and the
time, and I kind of enjoy doing the mods. I'll definitely spend some
time checking out the forum. . . .

> Remember to clean up the board and give it a good spray of sealant to
> prevent moisture poblems, and be careful, some of the traces on these
> things are very delicate.

Will do. BTW, what do you recommend as a spray sealant?

Regards,
Joe
 
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Cunning Ham wrote:
> What did you swap those transistors out with?
> I might want to try this mod myself, any other details?

Well, you've probably had a look into the forums Chris posted by now, so
I won't be telling you anything new. I used 2N5087 for the 5401s, as
per Scott Dorsey's mic article from Recording Mag a few years back. I
replaced the 5551 with MPSA18, though I'm not sure that will have an
audible effect. Good luck!

Regards,
Joe


>
> "Joe Kramer" <musetrap@earthlink.net> wrote in message
> news:xRple.874$MI4.448@newsread2.news.pas.earthlink.net...
>
>>Hi!
>>
>>Anyone have a line on schemos for this mic? Already replaced the 2N5401
>> & 5551 xstrs and got an improvement in top end. Would like to do
>>further upgrades, mainly caps. Thanks!
>>
>>Regards,
>>Joe
>
>
>
 
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I don't have a clue as to what you're talking about. My 603s have been on
maybe 100 Steinway recordings without a single honk. Now Mike Rivers did
seem to sense some noise at one point on a different setup, but I believe it
was the Soundcraft, for certainly nothing has been untoward on my Crest, and
like I said, 100 recordings don't lie.

But I guess some people just HAVE to change things. Until I get proof that
these mics need something different, I'll just keep using them as I have and
enjoy the results. I do have examples.

--


Roger W. Norman
SirMusic Studio
http://blogs.salon.com/0004478/
"Chris Cavell" <chriscavell@cavellstudios.com> wrote in message
news:1117237355.304415.196030@g43g2000cwa.googlegroups.com...
> They have a bit of a "honk" to them that can make tonal full range
> instruments, like piano, really ugly on specific notes. Swapping out
> several of the caps (all ceramic) to film or styrene tends to cure this
> for the most part. BTW, the 990 and 991 are identical...the 990 just
> has a rather nifty mounting scheme for the small di capsule to make it
> side adress (and appear like a large di to anyone who doesn't look
> carefully). The circuits are identical and use the exact same
> componentry, but the number designations on the circuit boards change
> from one model to the next.
>
> Unofficial means that he basically doesn't want to catch any "gruff" if
> their are errors...it's basically the standard schoeps circuit.
>
 
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"Roger W. Norman" <rnorman@starpower.net> writes:

> I don't have a clue as to what you're talking about. My 603s have been on
> maybe 100 Steinway recordings without a single honk. Now Mike Rivers did
> seem to sense some noise at one point on a different setup, but I believe it
> was the Soundcraft, for certainly nothing has been untoward on my Crest, and
> like I said, 100 recordings don't lie.
>
> But I guess some people just HAVE to change things. Until I get proof that
> these mics need something different, I'll just keep using them as I have and
> enjoy the results. I do have examples.
>
> --
>
>
> Roger W. Norman
> SirMusic Studio
> http://blogs.salon.com/0004478/
> "Chris Cavell" <chriscavell@cavellstudios.com> wrote in message
> news:1117237355.304415.196030@g43g2000cwa.googlegroups.com...
> > They have a bit of a "honk" to them that can make tonal full range
> > instruments, like piano, really ugly on specific notes. Swapping out
> > several of the caps (all ceramic) to film or styrene tends to cure this
> > for the most part. BTW, the 990 and 991 are identical...the 990 just
> > has a rather nifty mounting scheme for the small di capsule to make it
> > side adress (and appear like a large di to anyone who doesn't look
> > carefully). The circuits are identical and use the exact same
> > componentry, but the number designations on the circuit boards change
> > from one model to the next.
> >
> > Unofficial means that he basically doesn't want to catch any "gruff" if
> > their are errors...it's basically the standard schoeps circuit.
> >

To Chris: Thanks for the schematic. It looks like they're using a proper
circuit.

To Roger: So, are they that good? I was wondering more about the
quality/consistency of the capsules than the electronics. Call me
conservative, but if I needed a mic for (paying) recording gigs, I might go
for AKG, Audio Technica, etc. Or are those made in China too? The MXL might
be good for live sound though. At least you wouldn't worry about damage or
theft.

Richard
 
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Yeah, kind of odd how they advertise them differently...but they do
state for both a 20mm 6 micron diaphragm, but call it large in one mic
and small in another. Go figure...
 
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Roger,

Yeah, I don't trust their published pattern sheets at all...the 991's
and 603's made within the last year or two are completely
identical...all the way down to the mesh lining the vents.

All in all I consider the 603/991 to be the best sub-hundred buck mic
on the market.

They just had this sort of ring with my particular favored micing
technique (serving as spots augmenting a more distant C426 in blumlein)
that disappeared with other small di's, but was present regardless of
the which of the 3 steinway's I had available in the room at the time.
It tended to make them unusable for me (for piano) in the jazz combos I
record regularly with all the upper three octave comping and soloing
going on. For those I often wound up replacing the mxl's with the c426
in the same position, or a pzm with a figure 8 head on a SE300B body
taped to it for an MS setup.

Cheers,
Chris
 
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In article <1117237355.304415.196030@g43g2000cwa.googlegroups.com> chriscavell@cavellstudios.com writes:

> BTW, the 990 and 991 are identical...the 990 just
> has a rather nifty mounting scheme for the small di capsule to make it
> side adress (and appear like a large di to anyone who doesn't look
> carefully).

I suspected as much, but the ad copy says "large diaphragm." Perhaps
that's really meant to be two words and not a phrase. "Large" as in
it's bigger than the small one, and "diaphragm" as in every mic has
one. Where's Obviousman when we need him?

According to the poop sheet, the pattern (or maybe it was the
frequency response curve - I don't remember now) looked better for the
991, something (both, actually) that I would expect for having less
grill around the capsule.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
 
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I normally reserve them for piano as I have other small condensers for drum
overheads and acoustic guitar. But I think I've made a believer out of a
few people. Of course, it's not just in the mic, but placement, the quality
of the piano and what you do in processing, but I can say that I think I
know placement, a Steinway isn't usually shabby, and I have never had to EQ
these mics, either on the way in or on mixdown, so to me that makes for a
pretty reliable and good sounding mic.

And yes, I've used KM84s, 184s and 140s on Steinways so I have a point of
reference. Oh, I've also used Scott Dorsey's 441s and my MXL 990s on piano.
Only the 990s disappointed me, but I believe that was my fault in correct
positioning as just a tad of EQ corrected the very slight phase problem.
They made the Steinway a bit brighter than I like for jazz, but most people
wouldn't notice.

I'll have to give the 603s a try on acoustic when I get a good one over
here.

For the price I'd say get two pair, mod one, use both pairs on the same
recording and see what you think. Oh, I did get mine from Brent Casey when
he was with MXL, but he only did some close checking on consistency for me.
No mods.

--


Roger W. Norman
SirMusic Studio
http://blogs.salon.com/0004478/
<Mannr@uwaterloo.ca> wrote in message news:87ekbsdukv.fsf@uwaterloo.ca...
> "Roger W. Norman" <rnorman@starpower.net> writes:
>
> > I don't have a clue as to what you're talking about. My 603s have been
on
> > maybe 100 Steinway recordings without a single honk. Now Mike Rivers
did
> > seem to sense some noise at one point on a different setup, but I
believe it
> > was the Soundcraft, for certainly nothing has been untoward on my Crest,
and
> > like I said, 100 recordings don't lie.
> >
> > But I guess some people just HAVE to change things. Until I get proof
that
> > these mics need something different, I'll just keep using them as I have
and
> > enjoy the results. I do have examples.
> >
> > --
> >
> >
> > Roger W. Norman
> > SirMusic Studio
> > http://blogs.salon.com/0004478/
> > "Chris Cavell" <chriscavell@cavellstudios.com> wrote in message
> > news:1117237355.304415.196030@g43g2000cwa.googlegroups.com...
> > > They have a bit of a "honk" to them that can make tonal full range
> > > instruments, like piano, really ugly on specific notes. Swapping out
> > > several of the caps (all ceramic) to film or styrene tends to cure
this
> > > for the most part. BTW, the 990 and 991 are identical...the 990 just
> > > has a rather nifty mounting scheme for the small di capsule to make it
> > > side adress (and appear like a large di to anyone who doesn't look
> > > carefully). The circuits are identical and use the exact same
> > > componentry, but the number designations on the circuit boards change
> > > from one model to the next.
> > >
> > > Unofficial means that he basically doesn't want to catch any "gruff"
if
> > > their are errors...it's basically the standard schoeps circuit.
> > >
>
> To Chris: Thanks for the schematic. It looks like they're using a proper
> circuit.
>
> To Roger: So, are they that good? I was wondering more about the
> quality/consistency of the capsules than the electronics. Call me
> conservative, but if I needed a mic for (paying) recording gigs, I might
go
> for AKG, Audio Technica, etc. Or are those made in China too? The MXL
might
> be good for live sound though. At least you wouldn't worry about damage
or
> theft.
>
> Richard
>