McIntosh Power Guard Peak Limiter

Chat about Equipment Info

Re: McIntosh Power Guard Peak Limiter

Postby waldo041 » Wed Dec 09, 2009 6:41 am

mijknahs wrote:Another thing to consider is the slight breakup of the JBL E120s when they get pushed to *their* limit. Jerry was know to blow them more often than most of us ever will (I've never blown one in the 15 years I've been using them). I've seen Parish change a few out. A 50W Mac isn't going to breakup the JBLs like a 300W Mac will. Then there's the volume of the Twin preamp as well. It sounds totally different at 3 or 4 than it does at 7 or 8. (again -gotta check out that JGB 5/31/83 Rhapsody in Red opener. Talk about pushin it!)



you touch on actully two factors that WERE different from each other in the 70's vs. the 80's. the JBL K120's were used up until at least the closing of winterland, dec 78. a 3 k120 speaker cab would only be rated for 300watts and more apt to blow at clean pushed levels. so quite possible the volume was more tamed in the auditorium setting. 3 e120's would have a rating of 450 watts and leave much more room to push before breakup, however a good whack of the mutron 3, octave divider or both can trash those k & E's. i think that's how he blew the e-120's when he used those vs. being able to do the same or blow the K120's in a clean environment. it's most likely why he made the move to the e120 from the k120, more headroom.

the second factor is the twin pre's volume setting, with a blaster onboard wolf from the late fall of 77 set at roughly 10Db's up until tiger arrives, would cause him to keep the twin pre's volume much lower then when he played tiger which was slightly less then unity. a blaster set at the level jerry needed to even out the effects cabling, makes for a super hot guitar, but is tameabale by lowering the twin's preamp. so the my guess is the twins pre was more in the lower range of volume while the opamp buffer twin preamp volume was a lot hotter.

my point is, while it is the same mc2300 and twin preamp through these years, they definately are not the same setup's or volume settings once you throw the speaker ratings and buffers used into the circuit alone.

peace,
waldo
"Tone is in the instruments. Technique in the hands. Do what you will." ~ quote from some guy at the TGP forum
User avatar
waldo041
Senior Member
 
Posts: 2845
Joined: Thu May 19, 2005 10:58 am
Location: Indiana

Re: McIntosh Power Guard Peak Limiter

Postby SarnoMusicSolutions » Wed Dec 09, 2009 6:57 am

Rusty the Scoob wrote:Awesome discussion!

Would it be possible to build an outboard limiter that emulates the Macs VI limiter? Seems like you could run something like that between the preamp and any totally clean poweramp (even a high-tech Class D or something) and get the right "hair" at whatever volume you want.


I've been drawing up ideas for a while now, but haven't had the time to manifest it. But I'm definitely visualizing a single rack space device that operates as a clipper/limiter for line level signals. It would never be the same, but maybe we can get close.

I look at Jerry's 3-JBL setup (2.7 ohm load on the 2 ohm taps) as a 225 watt rig. That's 75 pretty clean watts per JBL, and actually a bit more if you consider the peak power rating of the amp. The Mc250 with 50 watts per JBL (or more like 75 watts peak power per JBL) will obviously not push the JBL's quite as hard as Jerry did, but still within 30% or so per speaker. So yeah, the stress on the JBL is lighter with the MC250, but there's still plenty of push to at least light the JBL's up a bit and make them work, especially with a K120. One channel of the Mc250 into one JBL is not quite the loudness of a Twin, but both channels of the Mc250 is definitely louder than a typical 80 watt Twin, or maybe in the ballpark of a 135W ultralinear Twin.

Brad
... and it's just like any other day that's ever been...
User avatar
SarnoMusicSolutions
Senior Member
 
Posts: 1058
Joined: Tue Jan 27, 2009 6:15 pm
Location: St. Louis, MO - USA

Re: McIntosh Power Guard Peak Limiter

Postby RiverRat » Wed Dec 09, 2009 8:26 am

Rusty the Scoob wrote:Awesome discussion!

Would it be possible to build an outboard limiter that emulates the Macs VI limiter? Seems like you could run something like that between the preamp and any totally clean poweramp (even a high-tech Class D or something) and get the right "hair" at whatever volume you want.


The short answer is.... No.

When it comes to the MC2300, because of the balancing act between what is happening in the power transistors, the VI Limiter and the autoformer... The likelihood you could emulate it without copying the design and essentially building a MC clone is highly unlikely.

Of course the moment you say something can't be done... Someone (like Brad) comes along and makes it happen and the answer is ridiculously simple but not readily apparent.

I watched a show on NatGeo last night about Hubble and they interviewed the engineer that saved that whole project by designing a "corrective lens" to compensate for the alignment issue of the mirror, a fix that was simply brilliant.
RiverRat
Senior Member
 
Posts: 961
Joined: Thu Apr 10, 2008 10:38 am

Re: McIntosh Power Guard Peak Limiter

Postby Rusty the Scoob » Wed Dec 09, 2009 8:43 am

SarnoMusicSolutions wrote:
Rusty the Scoob wrote:Awesome discussion!

Would it be possible to build an outboard limiter that emulates the Macs VI limiter? Seems like you could run something like that between the preamp and any totally clean poweramp (even a high-tech Class D or something) and get the right "hair" at whatever volume you want.


I've been drawing up ideas for a while now, but haven't had the time to manifest it. But I'm definitely visualizing a single rack space device that operates as a clipper/limiter for line level signals. It would never be the same, but maybe we can get close.

I look at Jerry's 3-JBL setup (2.7 ohm load on the 2 ohm taps) as a 225 watt rig. That's 75 pretty clean watts per JBL, and actually a bit more if you consider the peak power rating of the amp. The Mc250 with 50 watts per JBL (or more like 75 watts peak power per JBL) will obviously not push the JBL's quite as hard as Jerry did, but still within 30% or so per speaker. So yeah, the stress on the JBL is lighter with the MC250, but there's still plenty of push to at least light the JBL's up a bit and make them work, especially with a K120. One channel of the Mc250 into one JBL is not quite the loudness of a Twin, but both channels of the Mc250 is definitely louder than a typical 80 watt Twin, or maybe in the ballpark of a 135W ultralinear Twin.

Brad


That's exactly what I was picturing as well... a one rack-space unit that provides that specific limiting quality at a line level.

I'd much rather be on stage with somebody who gets close at 50 watts than who nails it at 225. :lol:
User avatar
Rusty the Scoob
Senior Member
 
Posts: 2303
Joined: Mon Mar 03, 2008 5:28 am
Location: Concord, MA

Re: McIntosh Power Guard Peak Limiter

Postby SarnoMusicSolutions » Wed Dec 09, 2009 10:53 am

Exactly. I want to be able to get something close to that sound, but at any volume. I'd like to have parameter controls such as the actual limiting threshold, the blend of dirt, and the character of the harmonics that make up the dirt. Surely we won't have the saturated JBL factor, but we're talking about emulating an effect. Hard and fast and aggressive peak limiting (peak smoothing) with a bit of grit and sparkle, and some actual distortion to be layered in. Maybe some actual transistor clipping into a real but small transformer to get some of that iron core saturation harmonic effect. Maybe a true VI Limiter but on an extremely low power scale. It'll take some experimentation for sure, but hopefully something musically useful and somewhat close will come of it. Y'all here on the forum will be the first to know about it when it happens. Please share any and all thoughts you'd like to contribute to the cause.

Brad
... and it's just like any other day that's ever been...
User avatar
SarnoMusicSolutions
Senior Member
 
Posts: 1058
Joined: Tue Jan 27, 2009 6:15 pm
Location: St. Louis, MO - USA

Re: McIntosh Power Guard Peak Limiter

Postby tapestry » Wed Dec 09, 2009 5:04 pm

I love this thread....as the search for the sound gets clearer and clearer! Im going to see Stu Allen on Thursday, Ill check out his rig then and take some pix of it as well. I hope Melvin remembers me!

The rack mounted McLimiter should be made and available. Please! I looked into ebay for the mcintosh amps and was dismayed at how much you have to pay for a 30 year old amp that might break down in the near future. I would much rather have the McLimiter and use a quality new solid state to achieve the same effect. There HAS to be a way to do it!
User avatar
tapestry
Bobby
Bobby
 
Posts: 355
Joined: Tue Sep 22, 2009 11:47 am

Re: McIntosh Power Guard Peak Limiter

Postby jdsmodulus » Wed Dec 09, 2009 5:26 pm

I too love this thread and I would say please put me on the wait list for the MCLimiter if we ever get one of these developed I want in!
jdsmodulus
Senior Member
 
Posts: 1252
Joined: Tue Dec 02, 2008 2:12 pm

Re: McIntosh Power Guard Peak Limiter

Postby mijknahs » Wed Dec 09, 2009 6:06 pm

Well, I'm glad this is an enjoyable thread too.

Brad, thanks for the info on the MC250 volume. I know someone with an MC50 (mono block) for sale (just one). I would get it if it would be loud enough for me. I'm not sure but it sounds like it might not be. I might pick up an MC2505 and try it out. I assume it's the same internally as the MC250.

Mike - You are right. I forgot he was using K-120s in the 70's. A lot of things changed when Tiger came along. So, maybe Jerry wasn't pushing the MC2300 as hard in the 70's as he was in the 80's. If you and Brad were arguing that the **80's sound** was the MC2300 being driven to the point of clipping (and Sentry Monitor engaging), I'd probably go along with that. At least in certain years.

I was just listening to 6/30/84 today and noticing how in Deal, Jerry's solo really had that "hair" (also the low A chords are pretty chunky too). Especially when he goes up to the higher part in the solo, some of the notes that blend together have a really nice, subtle harmonic distortion. Certainly not as common in the late 70's. Check it out here:
http://ia301142.us.archive.org/1/items/ ... d_64kb.mp3

Jim
User avatar
mijknahs
Senior Member
 
Posts: 1516
Joined: Fri Nov 13, 2009 8:51 pm
Location: Los Angeles, CA

Re: McIntosh Power Guard Peak Limiter

Postby SarnoMusicSolutions » Wed Dec 09, 2009 6:44 pm

So on that '73 JGB Live at the Keystone stuff, to me that's real squashed and dirty (in that cleanish Jerry way). The solo tones are real leveled off and cutting. That was the Mc2300 and Wolf with strat pickups, right? Listen to Finders Keepers. Far from clean full of sustain and sweet, gritty bite.


Brad
... and it's just like any other day that's ever been...
User avatar
SarnoMusicSolutions
Senior Member
 
Posts: 1058
Joined: Tue Jan 27, 2009 6:15 pm
Location: St. Louis, MO - USA

Re: McIntosh Power Guard Peak Limiter

Postby SarnoMusicSolutions » Wed Dec 09, 2009 7:18 pm

Check out Dew from that May 8, '77 Barton Hall show. Full of grungy Mac abuse. Deal has it too, but I agree he's going easier on the amp than that mid/early '80s stuff.

I think that a lot of what's happening in the '77 stuff that's harder to hear is the limiting when the peaks just barely feather the Mac's threshold. That's more of a dynamic leveling of the notes without all that much audible dirt. But the more he plays above that threshold, the more the real dirt enters the picture. The limiter action, to my ears, is very present, even all thru Deal and especially in the Deal solo. One revealing factor is the extra reverb that follows some harder played licks. That indicates that the guitar picked hard enough to trigger even more reverb, yet the power amp leveled the note off while the reverb trail, which lives well below the amp's power threshold, comes thru relatively louder than softer played stuff. Anyone who's driven a Fender Reverb tube amp real hard into clipping has heard this effect.

Brad
... and it's just like any other day that's ever been...
User avatar
SarnoMusicSolutions
Senior Member
 
Posts: 1058
Joined: Tue Jan 27, 2009 6:15 pm
Location: St. Louis, MO - USA

Re: McIntosh Power Guard Peak Limiter

Postby mijknahs » Wed Dec 09, 2009 10:26 pm

Okay. Maybe on some of the songs/parts of songs you mentioned (in the late 70's) but still hard for me to accept that the Mac was driven into current limiting (Sentry Monitor) on *every single note* in the late 70's. During the 80's - much more likely.


Jim
User avatar
mijknahs
Senior Member
 
Posts: 1516
Joined: Fri Nov 13, 2009 8:51 pm
Location: Los Angeles, CA

Re: McIntosh Power Guard Peak Limiter

Postby SarnoMusicSolutions » Wed Dec 09, 2009 11:03 pm

I think I agree with you on that. I guess that when I said "every note", maybe I should instead say something like "every loud note". Jerry is plenty dynamic and I'd agree that the '70s stuff does have a lot of clean to it along with plenty of it crossing into amp drive.


Brad
... and it's just like any other day that's ever been...
User avatar
SarnoMusicSolutions
Senior Member
 
Posts: 1058
Joined: Tue Jan 27, 2009 6:15 pm
Location: St. Louis, MO - USA

Re: McIntosh Power Guard Peak Limiter

Postby mijknahs » Thu Dec 10, 2009 1:46 am

Right on, Brad. Thanks for piquing my interest in the lower volume Macs (and maybe everyone else's too?). It would really be cool to get that harmonic, clean "distortion" (like the '84 Deal).

The Quest continues...
User avatar
mijknahs
Senior Member
 
Posts: 1516
Joined: Fri Nov 13, 2009 8:51 pm
Location: Los Angeles, CA

Re: McIntosh Power Guard Peak Limiter

Postby SarnoMusicSolutions » Thu Dec 10, 2009 7:52 am

I think that some critical keys in the formula to that '84 sound you're referring to would include:

Dimarzio Super II's run as single coil
McIntosh Mc2300, Mc2100, Mc250, and similar (and all of the metered/faceplated counterparts ie. Mc2105, 2505, etc.)
JBL K or E 120's
Adamas Graphite pick
Twin preamp or Twin type preamp with good reverb and plenty of it - bass turned way down
9v buffer like Waldo's Tiger clone
10-46 very fresh strings
high quality drugs (optional)

And drive the Mac amp into that range where it's squashing quite a bit, but not TOO hot to where it's purely grungy. Only let the loudest picked stuff cross into the audibly dirty zone. The medium picked stuff will be compressed or limited and a bit dirty, but less dirty than the hard picked stuff. These smaller Mac's can be pushed too far and they will get way too distorted. There's a zone to find and operate within.


Brad
... and it's just like any other day that's ever been...
User avatar
SarnoMusicSolutions
Senior Member
 
Posts: 1058
Joined: Tue Jan 27, 2009 6:15 pm
Location: St. Louis, MO - USA

Re: McIntosh Power Guard Peak Limiter

Postby tigerstrat » Thu Dec 10, 2009 10:36 am

SarnoMusicSolutions wrote:I think that some critical keys in the formula to that '84 sound you're referring to would include:

Dimarzio Super II's run as single coil
McIntosh Mc2300, Mc2100, Mc250, and similar (and all of the metered/faceplated counterparts ie. Mc2105, 2505, etc.)
JBL K or E 120's
Adamas Graphite pick
Twin preamp or Twin type preamp with good reverb and plenty of it - bass turned way down
9v buffer like Waldo's Tiger clone
10-46 very fresh strings
high quality drugs (optional)


... and lots and lots of Haagen-Dazs.
"There, in huge black letters, was 'The Grateful Dead'. It just... cancelled my mind out."-Garcia
User avatar
tigerstrat
Senior Member
 
Posts: 4631
Joined: Wed Nov 30, 2005 1:20 pm
Location: Portland,OR

PreviousNext

Return to Grateful Dead Equipment Discussion

Who is online

Users browsing this forum: No registered users and 0 guests