MXL 603S Schematics?

Archived from groups: rec.audio.pro (More info?)

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."

Archived from groups: rec.audio.pro (More info?)

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."

Archived from groups: rec.audio.pro (More info?)

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."

Archived from groups: rec.audio.pro (More info?)

Digging a bit I think I may have found you a schematic:

http://www.omnipressor.com/MicSchLib/MXL603S.jpg

Archived from groups: rec.audio.pro (More info?)

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

Archived from groups: rec.audio.pro (More info?)

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

Archived from groups: rec.audio.pro (More info?)

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.
>

Archived from groups: rec.audio.pro (More info?)

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.
> >

Archived from groups: rec.audio.pro (More info?)

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
>

Archived from groups: rec.audio.pro (More info?)

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...

Archived from groups: rec.audio.pro (More info?)

And by the polar pattern diagram, the 991s are so wide of a cardioid that
they are virtually omni, while the 990s have a decided lobe at 180, making
them more supercardioids. The 603s are a very wide cardioid with a virtual
negative response from behind. Probably all the exact same capsule as is
the 993, which looks the best of the bunch on paper if you don't mind the 12
kHz bump.

--


Roger W. Norman
SirMusic Studio
http://blogs.salon.com/0004478/
"Mike Rivers" <mrivers@d-and-d.com> wrote in message
news:znr1117282564k@trad...
>
> 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

Archived from groups: rec.audio.pro (More info?)

In article <e9udnUIzdqq2CwXfRVn-2g@rcn.net> rnorman@starpower.net writes:

> On the MXL page they have the 990s as a Large 20mm
> diaphragm, and on the 991s, it's just a 20mm diaphragm. Maybe I'll have to
> pick up a couple of 991s and see if there's a major difference.

I was curious about that. 20mm is a little smaller than "large" but
kind of big to be "small." I don't know where they measure that
dimension on a microphone capsule or if there's even a standard way of
measuring it, but since the outside diameter of the 991 case at the
business end is only 22.4 mm, that hardly leaves room to suspend a
20 mm capsule with much vibration isolation even if they measure it at
the outer diameter of clamp ring and backplate (with actual diaphragm
being perhaps 4 or 5 mm less in diameter.



--
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

Archived from groups: rec.audio.pro (More info?)

"Joe Kramer" <musetrap@earthlink.net> wrote in message
news:Ns7me.1525$s64.423@newsread1.news.pas.earthlink.net...
> Chris Cavell wrote:
>> 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.
>
> FWIW, I just recorded a small ensemble of autoharp, tamborine, and
> electric bass. I used coincident-pair 603s (unmodded except for the xstrs
> so far), through a VMP-2. I did get a bump in the 8k region that made the
> tamb sound shrill, but my placement and my room proabably were not ideal.
> EQ mostly cured the problem, but I hope to hear some improvement after the
> cap mods. Thanks again, Chris, for the helpful info and links.
>
> Regards,
> Joe

I'm surprised with all the modding boards I've been looking at (like for the
603S or the much-vaunted 3630 mod) there's not a single before/after clip to
be found anywhere. Are the gains so minimal that documenting them (at least
in MP3) would be useless?

Archived from groups: rec.audio.pro (More info?)

Replace the 2SK170 with either a Linear Systems LSK170 or a Siliconix
J305. Replace the output transistors with Hitachi 2SA1083's. Replace
the .22 uf output caps with Wima MKS-2 or fit a Mono ceramic 1 uf with
a .01 polyprop film bypass to extend the low end. replace the 680 pf
input cap with a Wima FKP-2 1k v or a MIT PPMFX 1000 pf. Replace the
2.2 k resistors with Dale RN55. Replace the 150 k resistors with 100k
Dale RN55. Replace the 1N4148 diodes with 1N4394's. This will increase
the polarization voltage to the capsule.

That ought to get ya all started, could make this sound pretty good.

BTW, this is another variation of the Schoeps CMC mic circuit.

Jim Williams
Audio Upgrades

Archived from groups: rec.audio.pro (More info?)

jwilliams3@audioupgrades.com writes:

> Replace the 2SK170 with either a Linear Systems LSK170 or a Siliconix
> J305. Replace the output transistors with Hitachi 2SA1083's. Replace
> the .22 uf output caps with Wima MKS-2 or fit a Mono ceramic 1 uf with
> a .01 polyprop film bypass to extend the low end. replace the 680 pf
> input cap with a Wima FKP-2 1k v or a MIT PPMFX 1000 pf. Replace the
> 2.2 k resistors with Dale RN55. Replace the 150 k resistors with 100k
> Dale RN55. Replace the 1N4148 diodes with 1N4394's. This will increase
> the polarization voltage to the capsule.
>
> That ought to get ya all started, could make this sound pretty good.
>
> BTW, this is another variation of the Schoeps CMC mic circuit.
>
> Jim Williams
> Audio Upgrades

Thanks for the info. This is great!

I'm wondering (I think I asked before...) about the quality/consistency of the
*capsules* themselves. I mean no amount of electronics hacking is going to
fix a bad capsule. So, does anyone know the consistency/quality? I'm looking
at both MXL603s and other clone/unlabelled versions, like Apex 180, and I'm
sure there are many others. These are *identical* in appearance to the MXL,
and a lot cheaper. The Apex 180 also comes with interchangeable omni/card
caps.

Thanks again,
Richard

Archived from groups: rec.audio.pro (More info?)

Good point. Only time will tell, since small tolerances will show up in
problems if it's not a quality build.

So far, the 603s are still working fine, even with your notice of noise
since it didn't present itself in subsequent testing, and the 990s are still
functioning correctly.


--


Roger W. Norman
SirMusic Studio
http://blogs.salon.com/0004478/
"Mike Rivers" <mrivers@d-and-d.com> wrote in message
news:znr1117300578k@trad...
>
> In article <e9udnUIzdqq2CwXfRVn-2g@rcn.net> rnorman@starpower.net writes:
>
> > On the MXL page they have the 990s as a Large 20mm
> > diaphragm, and on the 991s, it's just a 20mm diaphragm. Maybe I'll have
to
> > pick up a couple of 991s and see if there's a major difference.
>
> I was curious about that. 20mm is a little smaller than "large" but
> kind of big to be "small." I don't know where they measure that
> dimension on a microphone capsule or if there's even a standard way of
> measuring it, but since the outside diameter of the 991 case at the
> business end is only 22.4 mm, that hardly leaves room to suspend a
> 20 mm capsule with much vibration isolation even if they measure it at
> the outer diameter of clamp ring and backplate (with actual diaphragm
> being perhaps 4 or 5 mm less in diameter.
>
>
>
> --
> 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