Anybody else still have their McIntosh amp clinic results?

dB Cooper · « **on:** 22 Apr 2011, 08:37 pm »

This may be out of place but I thought I'd post it here knowing Frank's long experience with the old Dyna stuff . It easily bet specs EXCEPT for a rise in distortion centered at 10KHz in both channels. More puzzling (to my non-EE mind anyway) is that the distortion drops back to within spec at 20 KHz. Any other packrats kept their report? I built my amp from a kit when I was 14 or 15. This unit was later rebuilt by Van Alstine with his complete Mosfet circuit set (what a difference.)
Any interesting stories from anyone who attended one of these clinics?

dynaflo · « **Reply #1 on:** 22 Apr 2011, 08:45 pm »

I remember having my Dyna 410 that I build from a kit tested at a Mac clinic. Probably around '75 or 76.

dlparker · « **Reply #2 on:** 22 Apr 2011, 08:58 pm »

Quote from: dB Cooper on 22 Apr 2011, 08:37 pm

This may be out of place but I thought I'd post it here knowing Frank's long experience with the old Dyna stuff . It easily bet specs EXCEPT for a rise in distortion centered at 10KHz in both channels. More puzzling (to my non-EE mind anyway) is that the distortion drops back to within spec at 20 KHz. Any other packrats kept their report? I built my amp from a kit when I was 14 or 15. This unit was later rebuilt by him with his complete Mosfet circuit set (what a difference.)
Any interesting stories from anyone who attended one of these clinics?

This is fascinating stuff! I should have had some of my kit builds (Hafler DH-200, for one) checked out, but I never did.

And the real question is: "All other factors being equal" (obligatory caveat), can the average person actually HEAR the difference in your SCA-80 and McIntosh's ideal?

dB Cooper · « **Reply #3 on:** 22 Apr 2011, 09:22 pm »

I built a DH200 (and DH101) also but never had them tested.

Good page about the history of the clinics here

AVnerdguy · « **Reply #4 on:** 22 Apr 2011, 09:44 pm »

I built a Dynaco ST-120 amp kit in 1973 (?). My first real hi fi build. Sound of Music (later to become Best Buy) sponsored the Mac clinics and I brought it in to see if it met specs. The gentleman had a look on his face that made me think there was something really wrong and I had blown $150.00 of grass cutting money on a piece of crap. He was amazed that yes, indeed it met published specs.

Appears very few did because there was a procedure where you wrapped a very long piece of wire around the PS caps – to make a cheap inductor. He said that most amps rolled off the low end severely because of that coil. I was a pretty proud 17 year old kid. It tested as good as my friends HK Citation 12 which cost considerably more.

Wish I still had that graph but it went with the amp when I sold it. The piece of crap went up in smoke shortly after that when the guy I sold it to paralleled some 4 Ohm speakers. That’s when I learned how to service SS amps

FullRangeMan · « **Reply #5 on:** 22 Apr 2011, 10:14 pm »

I would love to see the Bob Carver's amp Clinic Result, as the Carver amp shot down the circuit breaker from the building...

> Never go to a psychiatrist, adopt a cat or dog from the street. On the streets pets live only two years average.

rlee8394 · « **Reply #6 on:** 23 Apr 2011, 12:01 am »

Wow, the House of Sound on Kent Ave. I grew up about a mile from there! I also remember Stereoland in Ingelside Shopping center and Lafayette on Rolling Rd. Brings back fond memories of my early years in Hi-Fi!!

Ron

thunderbrick · « **Reply #7 on:** 23 Apr 2011, 01:10 am »

I grew up in North Baltimore, and in 1969 my father bought a used Thorens TT with a 16" arm, and later a used Empire table, both from House of Sound. I think we got the Thorens coming back from a camping trip the day or two after the first moon landing.

Small world!

dlparker · « **Reply #8 on:** 23 Apr 2011, 01:18 am »

Quote from: thunderbrick on 23 Apr 2011, 01:10 am

I grew up in North Baltimore, and in 1969...

WOW! Balimer! I've actually been there, (summers of '66 & '67), but my earliest memories of Baltimore (besides the Orioles) is the COLTS! I'm still a diehard BALTIMORE Colts fan, and every time I go through the (usually self-inflicted) agony of having to watch Super Bowl III, a part of what's left of my mind hopes Shula will wise up and put Unitas in the game before he actually does, like second quarter...

thunderbrick · « **Reply #9 on:** 23 Apr 2011, 01:32 am »

Quote from: dlparker on 23 Apr 2011, 01:18 am

WOW! Balimer! I've actually been there, (summers of '66 & '67), but my earliest memories of Baltimore (besides the Orioles) was the COLTS! I'm still a diehard BALTIMORE Colts fan, and everytime I have to go through the agony of having to watch Super Bowl III, a part of what's left of my mind hopes Shula will wise up and put Unitas in the game before he actually does, like second quarter...

ME TOO! It was a disastrous year, a crushing time in my life, when, in one year the Orioles lost to the Mets, the Bullets went down (I think), the minor league hockey team lost in the finals (I think), and that fur-coat-wearing jackass beat the great Johnny U! Of course, it was a former BALTIMORE COLTS coach Weeb Ewbanks that coached the Jets that day of infamy.

EDIT: All-pro cornerback Bobby Boyd worked for my father in the off-season, I met Johnny U at his restaurant, and Artie Donavan owned a liquor store near where I lived.

I hope Robert Irsay rots in hell!

Now, back to House of Sound................

richidoo · « **Reply #10 on:** 23 Apr 2011, 02:50 am »

A friend of mine is a tech whose stores in Hartford hosted Mac clinics in the 80s. He showed me some unused blank forms, a little different than the one pictured above. Said it was a lot of fun.

dlparker · « **Reply #11 on:** 23 Apr 2011, 02:53 am »

Quote from: thunderbrick on 23 Apr 2011, 01:32 am

ME TOO! It was a disastrous year, a crushing time in my life, when, in one year the Orioles lost to the Mets, the Bullets went down (I think), the minor league hockey team lost in the finals (I think), and that fur-coat-wearing jackass beat the great Johnny U! Of course, it was a former BALTIMORE COLTS coach Weeb Ewbanks that coached the Jets that day of infamy.

EDIT: All-pro cornerback Bobby Boyd worked for my father in the off-season, I met Johnny U at his restaurant, and Artie Donavan owned a liquor store near where I lived.

I hope Robert Irsay rots in hell!

Now, back to House of Sound................

You sent me to wikipedia with the Irsay reference. He IS currently burning in hell! I knew Jim had taken over operations of the team, but I didn't know Robert was dead, just assumed it.

Those are some seriously nostalgic names you're conjuring up there. Artie is apparently still alive. Funny guy. Never had the opportunity to meet any of them, but I attended a Chiefs game at old Municipal Stadium in KCMO on Dec 22, 1963 against the Jets. I've still got the program. Weeb was coaching the jets and Sherman Plunkett was the left OT. Not sure if Sample was with them yet (can't find the program).

Johnny U was (and STILL is - in my opinion) THE man. I still remember hearing the news of his death. All I had to hear the announcer say was something to the effect of "trademark high-top shoes and confident" something or other and I knew a true legend had passed.

I figure Johnny is currently heading up the "North" team, and Robt. Irsay owns the "South" team, and Johnny and cohorts (didn't Jim Parker pass recently, too?) kicks their butt every game.

HAL · « **Reply #12 on:** 23 Apr 2011, 03:12 am »

I had my Hafler DH200 tested that I built from a kit at a MAC clinic in Rockville MD but never got the chart.

It met all the specs they checked from what I remember.

rlee8394 · « **Reply #13 on:** 23 Apr 2011, 03:23 am »

When Johnny U passed, Peyton Manning wanted to wear the trademark hightop shoes in honor of Unitas, but the damn NFL said they would fine him $5000.00 if he did. A classy gesture from Peyton in my opinion, although I think he should've done it anyway and pony (no pun intended) up the fine.

Ron

dlparker · « **Reply #14 on:** 23 Apr 2011, 03:57 am »

Quote from: rlee8394 on 23 Apr 2011, 03:23 am

When Johnny U passed, Peyton Manning wanted to wear the trademark hightop shoes in honor of Unitas, but the damn NFL said they would fine him $5000.00 if he did. A classy gesture from Peyton in my opinion, although I think he should've done it anyway and pony (no pun intended) up the fine.

Ron

I remember that! Five grand for him would've been pocket change.

Pun? I didn't notice one. You guys shouldn't horse around so much anyway ("Alan, stop all that horsing around!")..

dB Cooper · « **Reply #15 on:** 23 Apr 2011, 04:45 am »

Quote from: rlee8394 on 23 Apr 2011, 12:01 am

Wow, the House of Sound on Kent Ave. I grew up about a mile from there! I also remember Stereoland in Ingelside Shopping center and Lafayette on Rolling Rd. Brings back fond memories of my early years in Hi-Fi!!

Ron

House of Sound was sort of on Rt 1 although their address was Kent Ave. I remember they were demoing the ESS Heil AMT1's the night of the clinic. Stereoland had about four stores; the closest one to me was in Towson Plaza. There was a Lafayette in Hillendale (near Parkville)that I used to hang out at.

Surprising what pieces of paper I somehow managed not to lose over the years, I still have the sales receipt for my FM5 ($117 kit).

JerryM · « **Reply #16 on:** 23 Apr 2011, 04:52 am »

Hmmmm...

How hard would this be to recreate?

Not the experience of a Mac clinic, but the Test itself.

dB Cooper · « **Reply #17 on:** 23 Apr 2011, 01:07 pm »

Quote from: JerryM on 23 Apr 2011, 04:52 am

Hmmmm...

How hard would this be to recreate?

Not the experience of a Mac clinic, but the Test itself.

Well, here's what they used for the clinics (from the page I linked to earlier) :
600 lbs of gear in specially constructed cases.

This may have been later, after they started testing for IM instead of simple THD. The latter test apparently required two signal generators and was more complicated.

With time, a simple THD test has come to be viewed as being of limited usefulness. Even the spec-mongerers concede that IM levels are more indicative of sound quality. McIntosh later adopted something called the 'spectral distortion' test which was apparently designed to engage the soft-clipping feature in their amps while driving amps without this feature into severe distortion (it involved driving the amp 6dB past rated power.) Frank may know something about that.

dB Cooper · « **Reply #18 on:** 23 Apr 2011, 01:34 pm »

I also dig the hand-filled form and hand-drawn graph. No computers or printers back then!

thunderbrick · « **Reply #19 on:** 23 Apr 2011, 02:07 pm »

Quote from: dlparker on 23 Apr 2011, 02:53 am

You sent me to wikipedia with the Irsay reference. He IS currently burning in hell! I knew Jim had taken over operations of the team, but I didn't know Robert was dead, just assumed it.

About a year ago ESPN did a feature, I think called "The Band That Wouldn't Die" on the Colts leaving Baltimore, and the efforts of the Colts (all-volunteer) marching band to stay together for many years after Irsay snuck out in the middle of the night. Very powerful film making, very well done. I cried through parts of it. Shows what a drunken, low-life, lying piece of scum Robert Irsay was.

My sister is currently in the Ravens' band, BTW.

We now return you to our regularly-scheduled discussion of Mac amp clinics.