Good Thread
The schematic for the McIntosh Mc2100/2105 shows a Darlington pair. The Mc2255 series of amps are also supposed to use them. I was surprised to see the Mc2300 didn't have them, I always thought they were just a bigger version of the Mc2100/2105's.Originally Posted by Ian Mackenzie
I always liked my Mc2100. I had some college tuition money left over almost 20 years ago and purchased it from a studio somewhere in New York. It replaced a HK Citation 16A.
Thanks,
Scott
Guess I'll have to drag out my Crown Studio Reference-II and see how it compares. It's as much power as I own and seems to possess that Darlington architecture under discussion here.
". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers
I have a fuzzy memory of reading somewhere in the manual that if the amp was connected to power and the rear breaker was in the on / connected position the ODEP lights would stay illuminated but I would have to be read it all to be sure. I only know how this one amp behaves.
You have to have the end caps off to install rack screws and if the front of the rack side panels are deep enough to safely cover handles and knobs on the front of components you would not be able to access the side screws to reinstall the end caps. I have movable racks built in this manner and can see how the end caps could get forever separated from the amp. Bummer for us.
I will scan a cap and see if I can print a good part.
Barry.
If we knew what the hell we were doing, we wouldn't call it research would we.
I found that as well (not the part Barry found), but of course nowhere in the manual does it detail start up and shut down. I just thought it was strange given that when initially plugged in with the breaker in the "on" position but the front switch off, no lights on the display. Push the switch in up front, goes through it's deal, power light remains on as well as ODEP lights. Push switch again, every light goes out except the ODEP lights. I haven't tested for voltage at the speaker outputs though, especially if a signal was being fed to the amp.
Ooooh, that makes sense now. Bummer indeed. Thank you, Barry! Would be much appreciated.
On missing end-caps, I figure they were a pain in the ass to deal with and since these were used by professionals who couldn't care less about how they looked in their rack, they just didn't have time or patience to fuss over the damn caps.
". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers
Hello Gentlemen;
Your responses have given me much good to think about.
With the Baja 1000 behind us I have a bit more time to think and respond.
Rusty: Stereo for sure. I am using self-built RCA to XLR with pin 3 to RCA tip and pin 1 and 2 tied together at the RCA shell/ground. Built just for this old pin 3 hot amp.
Ian thank you for all the amp info. I am not an electronic wiz by any stretch of my imagination. I really appreciate you taking the time to elaborate.
I am going to run this 6290 as is for a while longer and load something else big and see what going back sounds like.
This UREI and the SAE are / were problem children and have been to several shops which failed to fix them. I take problem amps to shops new to me as a test to see if they are any sharper than the last shop that took my money and didn't deliver. This is partly the reason they have been so extensively worked over. Several shops really tried. It will be interesting to see if the other two 6290's sound like this one when they come back.
I am still loving this thing. It's so puzzling.
Thanks again guys.
Al my best.
Barry.
If we knew what the hell we were doing, we wouldn't call it research would we.
Howdy All;
Well, a year and about eight months later the UREI has been in the office rack unchallenged, and it has been very thoroughly enjoyed.
A couple of months ago I bought a very nice Crown Studio Reference II from its original owner. I have wanted one for a long time and being assured that it is functionally perfect and not wanting to chance it going bananas on auction, I paid the too high buy it now and eagerly awaited its arrival.
It shows up well packed and looks great, not perfect but very clean. A quick VOM test show nothing to be concerned about so in the rack it goes, and, dead channel. Nice.
The seller agrees to pay for it to be repaired based on the AE Techron estimate so off it went to the best outpost of the Crown mothership.
Turns out that is has cracked solder joints on the driver transistors that are mounted on the output board. Cracked in shipping, well,, maybe. While it was there, I asked them to really run it to be sure that all was as it should be.
It came back this week and tonight it went back in the office rack. After an hour or two I do like this amp. It will take me a couple of weeks to really get to know it but so far all good. It is bright, in a nice way like the SAE2400 so maybe the UREI is a bit subdued in the UHF.
I am going to have to re rack the UREI so I can somewhat quickly swap back and forth. I really like them both.
In a couple of weeks after a good long test here I will take it home and light up the Everests or the 4365's with it.
All my best All.
Barry.
If we knew what the hell we were doing, we wouldn't call it research would we.
Funny, you got your SR-II back in gear about the same time I got mine in gear. Damn thing is the heaviest amp I ever want to hustle around, screwed up my wrist playing with it over the weekend.(Getting old sucks, youth is wasted on the young) Anyway, my personal rant aside, the thing is killer on bass, my personal benchmark thus far given everything I've heard and played with. However, I have yet to test it above 90hz or so. That was supposed to happen today or tomorrow, but that'll have to wait until I can take off this brace on my wrist..
I'm enjoying mine, even if I never quite got it in a rack!
". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers
I don't have a rack either, can't seem to find any that aren't all industrial looking.
Nice filter, what do you use? I had AE Techron replace the rotting original in mine, but it doesn't look like much of a filter and doesn't sit flush after a day or so.
I also noticed your power switch is out (off), yet the ODEP lights are still on. That's exactly how mine behaves.
I bought a bulk roll of ATV air filter medium and cut it to fit. Seemed to match the deteriorating original very well. The lights, as I understand from the manual, simply indicate that the amp is plugged in to power and ready to be turned on. Mine came to me with satin-aluminum knobs and the ones in the photo are the clones from Ali-Express! Fit perfectly.
Now we need to find someone with the end-caps so we can have them 3D-printed.
". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers
Is that what you use for the bottom of your 4345's?I'm enjoying mine, even if I never quite got it in a rack!
No, I actually got it for the 250tis that are also on the project list (woofer surrounds). The 4345 seems to work just fine with a PS-200 on top and a PS-400 on the bottom. Never seen any lights come on so I doubt they're working very hard. When I bought the 4345 that was my concern but New Horizon told me the 18 had the same motor/magnet as a 15 and not to worry. He was running them on Haflers—well named since half of his seemed to be broken.
". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers
PS400, 72 Volts bridged? Yeah, your getting there.
Barry.
If we knew what the hell we were doing, we wouldn't call it research would we.
That's all thanks to the fine folks like you here on this forum. I really appreciate all the wisdom and patience you & others have given mePS400, 72 Volts bridged? Yeah, your getting there.
Barry.
Seriously, before I joined here I never thought I'd replace the old Marantz stuff I bought, let alone acquire speakers that weigh 200+ lbs and dominate the living room! Funny, because that has become my favorite room in the house.
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