I really liked the story John told where the band was playing Watkins Glen in upstate NY and some of the equipment got lost on the way. So they helicoptered one of the road crew to Binghampton where MacIntosh opened their factory on a Sunday to let them pick up some 2300's. The Wall of Sound was really the brainchild of Owsley "Bear" Stanley (Curl, Wickersham, and others were brought in to make it a reality) and didn't last long for economical reasons. There were actually two base setups that leap frogged each other as the band traveled from venue to venue. When they were playing on one set up, the other was in route to the next stop on the tour to be set up and waiting for the band to arrive. You can read Bear's notes on the Wall of Sound here: http://www.thebear.org/musicintro.htmlIf you ever saw the Grateful Dead movie which chronicled a 4 night run at the old Winterland in SF, you can see the road crew setting it up and hear the Wall of Sound in action. In one scene Phil Lesh is being interviewed and discusses the system and then demonstrates how it lets him play his bass as loud as he wants, which according to Garcia in an old interview (and who also used a Mac amp for a while), was nearly as loud as his rig. |
John Curl gave a most informative talk on the Wall Of Sound used by the Gratefful Dead. He had a lot to do with the speaker end of things but had not much to say about the amplifiers which left me curious about them.
I think JC was being diplomatic in his silence, he knows. As it was in a way McIntosh sponsored after all. There were 15 x MC-2300's in this link. http://www.dozin.com/wallofsound/
However this is a fine amplifier, virtually bullet proof, and used in great numbers by a band known for its incredible sound.
That maybe Roger back in the day, and yes any amp with an output transformer is far more immune to a degree against fools doing the wrong or stupid things like shorting out
(than a direct transistor output), but have a listen to one today compared to what's around, then give your opinion on how it sounds. I heard one not 2 months ago compared to a Gryphon on Wilson's, let me say there was no comparison. One sounded like a thick blanket was thrown over the Wilson's compared to the other, you'll know which when you've had a listen to one. Roadies tend to blow amps more than anyone I know, so yes the SS Mac's with output transformers would be up for more abuse, if the band could get tubes to do the job because of the watts needed, and the reliability factor. Can you imagine the amount of tubes needed to give the watts that 15 of those Mac's could give. Cheers George |
HI George,
I have not listened to one but I like the circuit, especially for its day when Phase Linear and Crown were the alternatives. I just appreciate a good design for the parts that were available at the time. Transistors have come a long way since then. This amp used a MJ15001 series part. Although they could have used the compliment they went with same sex devices. Its a really clever design,
As far as I know The Dead bought all those amps. There is even a story where they took a helicopter and $6000 to pick up some amps at the factory on a Sunday.
Did it really sound that bad? Anyone else heard one? |
This article is off topic. But, it’s a fun read about Owsley and the Dead’s introduction to good sound - and parallel universes. Below is a short excerpt. "At the time, live sound at rock concerts was extremely primitive. Musicians plugged their instruments into amplifiers connected to single-channel speakers. There were no onstage monitors, so musicians couldn’t hear one another. Owsley wanted the Dead not only to be clearly heard but also in stereo, a concept so far ahead of its time that it would be ten years before such systems were installed in movie theaters. Thanks to Owsley, the Dead were soon playing through four immense Altec Voice of the Theatre A7 speakers powered by four McIntosh 240 stereo tube amplifiers as delicate as they were huge." |
Did it really sound that bad? Yeah, to give a visual comparison, it was like looking through frosted glass. I remember sound from that era well, SS either tore your head off with sibilance usually from the US, or so truncated the opposite, usually from the UK, it sounded like a thick Blancmange. No wonder tube were the preferred choice by all. Owsley wanted the Dead not only to be clearly heard but also in stereo But this counters that if you look at the writing above each unit stack, as the same muso/instrument was in both left and right, giving basically a mono wall of sound. https://marketingtowin.files.wordpress.com/2011/02/dead-soundii.jpgCheers George |
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"Yeah, to give a visual comparison, it was like looking through frosted glass"
Complete BS or bias at best. I have not heard the MC2300 but I own a pair of MC2200s and have compared them with several modern SS amps in the $3K-$5K range and the they held their own and even sounded better when paired with the right speakers. I don’t expect them to sound better than likes of Gryphon or Pass Labs Class A amps but they did sound better than Pass Labs X250 driving my Martin Logans. Speaker pairing as always is important. |
kalaliComplete BS or bias at best. I have not heard the MC2300 ... Wow, talk about bias. How can you call BS regarding what someone heard from an amplifier that you admit to not having heard?
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+1 Cleeds, you can see it a mile off, just Mac owners protection mode bias coming into it.
He's done it before, with anyone saying anything slightly negative on Mac's.
Cheers George
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"How can you call BS regarding what someone heard from an amplifier that you admit to not having heard?"
That's a fair point but I look at the collective comments from this poster every time a McIntosh related topic comes up, most of the time insulting, e.g., autoformers, meters, sound quality, etc., etc. I have no loyalty to either the brand or the model (and prefer mine without meters).
Sorry about the off-topic post.
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I was hoping someone would compare the fine engineering of this amplifier compared to what Phase Linear, Crown, Quatre and otheres were doing at the time.
Auto transformers made this design extremely relaible. Ive never been a Mac Man but I have to appreciate good design when I see it. I don't like everything they build and I have worked on much of it. Their preamps have too many buttons in the signal path. But if kept clean they are not a problem.
I just wanted to share my discovery with others who might also appreciate it. In an earlier thread there were posts that called the autotransformer a bandaid for a poor design. It is the essence of this design. Anyone who understands safe operating area of transistors will appreciat this. Most amplifiers that fail are due to engineers who do not. Mac knew.
How an amplifier sounds is subjective and may depend as much as someones mood, their perception of value and cost and build.
George, I respect your posts here. However you are comparing the Gryphon on Wilsons to the Mac on what speaker? How many years between the comparisons? How many years between the amplifier designs...50 Years!
Do readers here know that almost all modern SS amps are a basic op-amp circuit done over and over again with fancier metal, more capacitors, where are we going with this? |
They were probably good in their day, Roger, but so were many others. But you would have them today as your main amp I think not. A solid state amp that has trouble driving a certain speaker load, can be helped with the use of an autoformer, I say save your money and get the right amp instead. All you have to do to prove it to yourself, is put a pair of Autoformers on ANY decent solid state amp that can drive hard loads, and hear what it does to the sound compared to when used without them, even on easy loads. All this fishing Roger, sounds to me like you may be ready to venture into solid state using output transformers? https://d2gg9evh47fn9z.cloudfront.net/800px_COLOURBOX29710931.jpgCheers George |
@georgehifi - sorry to say Roger won't be going down that path. He's just a curious guy that does a lot of research. When he heard Curl talk about the 2300's it got the better of his curiosity, especially given their use by the Grateful Dead with the Wall of Sound set up. So he looked into it and thought he would write about some of his thoughts and findings. If Roger was going down the path of building solid state amps, and he has built at least one I know of in the past, I'd be one of the first to hear about it.
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I built many solid state amps in my youth, not knowing of the AutoTransformer Macs. But then I was just a child. I did however get a firm understanding of how transistors fail and the circuits necessary for them to be protected against shorts and reactive loads. I learned about safe operating area (SOA). I saw that at the voltages required just to make a 100 watt amplifier would intrude into the SOA of all power transisitors and still does. So the designer has to protect the transistors. I found most of the protection schemes would cause premature clipping into reactive and low impedance loads.
When an amplifier sounds very bad on a particular speaker and good on others I contend it is misbehaving into that load. Two common examples are current limiting (load line limiting) and outright instabilitiy usually in the form of birdies (small HF oscillations on the wave that look like a bird on a wire). Birdies sound like the worst kind of clipping, yet the amp may be far from clipping.
This concept of matching speaker and SS amplifier appears to be misunderstood and a bit overrated. As stated above the particular speaker may make the amplifier unhappy. If the amplifier is happy then one may consider impedance variations that are exaserbated by high output impedance.
If I were to make SS amps I would like likely use autoformers because:
1. I know how to make them
2. They allow me to use the full rating of the transistors.
3. They allow me to use same sex transistors
4. They protect against DC faults
5. They present the optimum load to the amplifier via their taps
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If I were to make SS amps I would like likely use autoformers because:
Judging by this statement, as I know your no fool, and that you have never A/B’d a highly rated solid state amp that’s happy driving into a speaker considered to be a hard load, then place the "said" best autoformers in to see what they do. You will be surprised at just how much the sound degrades. Granted autoformers have their place with amps that cannot drive certain loads, but I say save the money and get the right amp instead, you’ll be far better off. If you have an OTL amplifier you should know that the power is greatly reduced into low impedance loads. Even worse is that low impedance loads will overheat the tubes at high power levels as most of the power supply voltage is being dropped across the tube not the load. So low impedance loads are hard on the tubes and cause higher distortortion All of these ills can be solved by the use of a proper Autoformer. OTL’s are the best sounding tube amps there are ( even maybe solid state also) if they are used withing their comfort zone driving speakers that have easy loads they like, as with the highly rated solid state amp above, that changes very much so once you introduce an autoformer, into the same system, I doubt that Ralph would use autoformers if there was no need to. It all comes back to the right amp for the right job, if not an autoformer can be a "band-aid" or "interim" fix, but an expensive one. Cheers George |
Can we agree that good amplifiers drive a large number of speakers very well and changing to another "good" amplifier will drive the chosen speaker just as well? These amplifiers have certain common characteristics that make them sound very similar on a wide variety of speakers.
Can we further agree that some amplifiers have (rather undesirable) measurable characteristics that will make a given speaker sound uniquely different on this amplifier. And though we might like the coloration this combintion produces, it is not what the speaker designer had in mind?
If the right amp has to be found for just some one speaker, I would say that is a bad amplifier waiting to find a home. How is one to find this perfect match? How many of these colored amplifiers would one have to audition? Take the current OTL amps which all have high output impedance. They can properly drive less that 10 % of the speakers out there. How about an OTL that can drive a wide variety of speakers properly?
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If the right amp has to be found for just some one speaker, I would say that is a bad amplifier waiting to find a home. So what your saying is an amp that can drive the Wilson Alexia’s known impedance of down to 0.9ohm is a bad amp????? No you’ve got that arse about face, the speaker is the problem being too hard to drive and the amp that can do it is a great amp, and will not only drive it but anything else as well. Definitely not
a bad amplifier waiting to find a home.
Cheers George |
How about an OTL that can drive a wide variety of speakers properly? No such thing, unless you stick an autoformer band-aid on it for the hard to drive ones. Then you ruined the whole advantage of the OTL design and what it can do. Your better off getting one of your amps to do the job if you wish to stick with tubes, or putting a proper output transformer on the OTL, again a backward step to what an unhindered OTL is capable of giving with the right speaker. Cheers George |
How about an OTL that can drive a wide variety of speakers properly?
No such thing, unless you stick an autoformer band-aid on it for the hard to drive ones. Then you ruined the whole advantage of the OTL design and what it can do.
Your better off getting one of your amps to do the job if you wish to stick with tubes, or putting a proper output transformer on the OTL, again a backward step to what an unhindered OTL is capable of giving with the right speaker.
Here is an interesting story that happend to me. Jim Jordan, the designer of Vaughn speakers fell in love with the Wavelength 300B Cardinal with silver transformers and all. Big bucks for a 7 watt amplifier. This amplifier has rather low damping, but within its power range I assume it to be a good amplifier. He named his speaker after the amplifier. In this case the amplifier came first and he designed a speaker he felt worthy of it as other speakers he tried were not. https://www.vaughnloudspeakers.com/storyThen he met me, actually I went to his house to hear his speakers. I took along a rough prototype of my OTL for him to hear. Somehow he convinced me to make one for him and one for his customer in stereo on a nice chassis. Now he uses my AUTOFORMER OTL all the time. It has very low distortion very low output impedance. It is of the Futterman School which always has low output impedance. Mine only two output tubes, triode connected, and one driver tube per channel. Most OTLs have 6-12 output tubes per channel. Lots of heat, lots of matching. The autoformer has no special materials, I make them of standard copper magnet wire and M6 Iron. It is very small, costing a fraction of a silver 300B transformer. It is partially in the feedback loop or not, as desired. Id does effect the sound and Jim moves it from time to time for different listening. He likes the subtle changes it makes. I wound 4, 8, 16 ohm taps and 32 ohms is direct output. At 32 ohms the amplifier puts out 30 watts into a 32 ohm load. An 8 ohm load connected to the 32 ohm tap produces 3 watts because the tubes can only provide that much current (about 1 amp). But any load connected to its proper tap will put out 30 watts. To my suprise the Autoformer extends the high frequency frsponse from 120 KHZ direct to 160 Khz using the 8 ohm autoformer tap into an 8 ohm load, or 4 into 4, etc. All the taps produce the same results into their specified load. I arrange a feedback wire on a lug and tell the user to move the feedback wire to whichever tap they are using so the feedback is always on the tap looking right at the speaker. Sometimes the put it on a different tap and like that better. Its all good, the amp is stable and happy. In closing the SA-6 I deisgned for Counterpoint and the large Futtermans will drive a wide variety of speakers with 100 watts per channel with very low distortion and high damping. Keep in mind that the Circlotron amplifiers are an entierly different animal. They do not have low output impedance of a lot of current. All OTLs are not the same I invite George and others to take a little time and learn about the Futterman style amplifiers and then say something. Little by little I will get around to all of it, but it took me years to fully appreciate his work, the man was very smart and I am happy I got to spend an afternoon in his shop. |
So what your saying is an amp that can drive the Wilson Alexia’s known impedance of down to 0.9ohm is a bad amp?????
No you’ve got that arse about face, the speaker is the problem being too hard to drive and the amp that can do it is a great amp, and will not only drive it but anything else as well. Definitely not a bad amplifier waiting to find a home.
Cheers George
I hope I didn't imply that. An amplifier that drive 0.9 ohms would be a very good amp if all other things were up to snuff. There are lots of both good an bad ways to drive an ohm. Speakers are the designer's sonic goal, his taste, his dream. In many cases he doesn't care how he gets there. Some care and some do not care about the difficulty of their load, not their problem. I would suspect most people who are serious about speaker design have good rather universal amps with high damping, lots of current and voltage. Why wouldn't they? Therefore if you buy their dream you had better ask its characteristics or how they drove it. On the other hand if someone is interested in 300B amps, like Jim Jordan, the speaker choices are limited and one is playing in an entirely different field which is not universal but has limitiations. Here the speaker/amplifier interactions are going to be important, obvious and likely hit you in the face like the Circulatron that produced a 8 db peak at 50 Hz and a marked loss of highs in my QUAD 63. The 8 dB peak surprised me so much I got a oscillator and meter and measured an 8dB rise at the speaker terminals at 50 Hz and many dB fall off about 400 Hz. The 63 was not longer Mr. Walker's 63. In the HI FI world some people design speakers that are hard to drive, yet there are many amps capable of driving them. At a wide range of prices. So what is all the fuss about? However what do we do with amplifiers that have high output impedance and limited current? People buy lots of them. May I remind all that the topic of this thread is about what an autotransformer can do for matching the load to the amp. Whether or not a Gryphon sounds better than the old Mac is not the issue and certainly not the money which few can afford. I also find it odd that Gryphon is not in Stereophile Rec Components, nor could I find a review or any mesurements. If someone has a link I would love to see this amp's performance. Perhaps is all just a pretty face. |
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The Mc 2300 was horrible ,the pots Mac used get dirty easily & begin to scratch when gain levels are changed and I'm not the 1st to experience that problem ,I'm a huge McIntosh fan/collector but the Mc-2300 performs as good as it dosent look ,I've got mig welders that look nicer . |
Well EXCUSE ME (Steve Martin). I guess its too much to ask to clean the pots of a 40 year old amplifier. FYI dirty pots can cause lots of contact (diode) distortion. You must have some very nice looking MIG welders. how do they sound?
How impartial of you to listen to and judge an amplifier that obviously has dirty pots. Any amp of that many years deserves a full checkout and bench test given its age. I have measured distortion go down by 100x just cleaning a pot. It also deserves respect for still working.
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