fuck yeah, that old Marantz gear is excellent.
model 2238b in my house
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fuck yeah, that old Marantz gear is excellent.
model 2238b in my house
My stuff is old. When It dies I take it to the Vintage Audio repair. I am not OP smart or patient. BB, I know you want to build your own amp, but I have a Hafler 500 that comes as a kit (if you can find one) that is a monster through my Klipsch Forte's. Honest to god concert loud and really clean sounding. No wonder I am going deaf.Quote:
Originally Posted by EWG
I had a hafler dh200 for a while that was a nice little amp. Had the matching preamp as well. Not the most aethetically pleasing stuff, but I thought sound quality and power was quite good.
I just picked up a broken Denon poa2200 and matching preamp yesterday. Denon is a beast, rated at 200wpc @8ohms, most say they measure out at 220w+. It has a power supply issue.
As for the amps where a channel goes in and out, are there gain knobs? Does it change if you turn the knob back and forth? Deoxit! Otherwise, you need to dive into the circuit, as it could be many things. If you have one good channel, and know how to use a dmm, you can give it a signal (no speaker) and start poking around and see where your voltage begins to stray from the good channel.
Norseman, the old marantz stuff is nice. Good looking and sounding. I recently fixed this one up and sold it. Fixed a power supply problem and relamped it. Cleaned all potentiometers. That was all it needed.
Attachment 335762Attachment 335763
sent from Utah.
BB, I love old Marantz receivers. If you ever have one you want to sell with power and a turntable in jack, I may be your guy. As much as I love the present system my B & K pre-amp does not have a turntable in jack and I would love to listen to some of my 200 vinyl albums again someday. I thought the Hafler had more juice than this: The Hafler DH-500 is a two channel audio power amplifier designed to the very highest performance stan-dards. It is available as a kit, or factory assembled. Its power rating of 255 watts per channel is very conservative, and it can deliver appreciably higher powers into impe-dances below the rated 8 ohms. That Denon should rock for you.
Guess I’ll start with deox. It doesn’t really cut in and out if I change the balance but if it’s out and you turn the volume up a little it will pop back in.
Classic case for deoxit. Open up the case, get good access to pot, (make sure it is unplugged, and caps have had time to discharge.) Put a tissue or something to catch the dripping. Spray liberally into the pot where the contacts are and turn back and forth like 50 times. Then do it again. Do it for all pots in the unit.
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You can get an external phono preamp and then feed the bk a line level signal into any input. There are lots out there, or you could take a crack at diy. Make sure you are getting the right gain for your turntable. Moving magnet and moving coil needle assemblies require different levels of gain. Some preamps have a switch to allow for either.Quote:
Originally Posted by liv2ski
sent from Utah.
I just gotta know, and maybe its been mentioned, but BB you do a tons of wrenching (very complicated sometimes) and now this electronics shit...are you just a genius or are you an engineer or something.Quote:
Originally Posted by basinbeater
Feel free not to divulge, but damn you know how to do some cool shit...im not geeky like that, but its cool to read for sure.
Probably should have been an engineer, but I'm just a bored mid level desk jockey for a large financial Corp. I have sort migrated naturally into the tech/strategic planning/problem solving side of things. Building automated solutions, getting around intentionally set up road blocks, streamlining stuff, data integrity, that sort of shit. But it's sort of a drag.
I just like messing around with stuff, and going down different rabbit holes. Figuring out how stuff works and tinkering. Really digging the electronics stuff right now though. Trying to figure out how to use ltspice so I can simulate circuits. I wouldn't mind plagiarizing/modifying/designing my own circuits and making some runs of amps or preamps or whatever. Maybe I can turn it into a business. Others have.
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Also, if anybody has cool old stereo shit, pm me and see if im interested in taking it off your hands. [emoji16]
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If you guys want to learn more go hang around diyaudio.com. I stumbled across it when I fixed my first amplifier, someone there helped me abit. Excellent forum with tons of info, and frequented by many professional ee.
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Thanks. Interesting hobbies.Quote:
Originally Posted by basinbeater
Sent from my Pixel 2 using TGR Forums mobile app
It's alive! I added a speaker turn on delay and DC protection circuit to the output, and buttoned everything up. I tested it in the basement with some less fancy speakers, then brought it up closer to it's destination resting place to give it a whirl. Lots of power. I need to run it a while and set the bias a little warmer. Check DC offset again on both channels. I want to add some Vu meters for the front, and resurface the faceplate so it doesn't say arcam or HDMI, or any of that crap. But that's all cosmetics. How's it sound so far? So far sounds great. Lots of power. Lots. I'm headed out of town, final tuning and critical listening will be postponed.... Anyway, project getting closer to completion. STOKED!
https://youtu.be/Ie27LiQb_skAttachment 336020Attachment 336021
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Well, the amp is done. I pulled it back out and made final adjustments to bias, DC offset, and input stage current. It is nicely set up now. I wired up the fans underneath the heatsinks to run about 40% of max speed, and they are nice and quiet and keep the temps in check. The maximum sustained output voltage is right around 38v ac rms(root mean square). Knowing that my speakers are nominal impedance 8 ohm, then I can calculate power output. 38vac^2/(8ohms)=180 watts. So 180watts per channel. Lots of power. How does it sound? It sounds awesome! More detail and power than I have ever heard from an amp. Bass slams hard on hip hop and is beautifully controlled for rock and classical. High are gorgeous and smooth. Mids are also very detailed and clear with strong punch. Maybe I'm biased (geek joke) because I built it, but it easily blows my old amp out of the water. But now when you have classical music turned up loud, it sounds like a goddamned orchestra is in the living room. Gotta spend some more time listening to really listen for imaging and sound stage and dynamics blah blah, but initial impressions are very very good.
Even the wife said it sounds better than the other one. But maybe she was just being nice so I will shut up about it.
Anyway, next project... Another amp! Going to build an amp based on the ksa gb150 by Greg ball. This one should be similar power, but in a more compact package. I will use a dead Yamaha receiver case, transformer, and heatsink. The heatsinks are tight together, and have a fan that blows through them and up a 'chimney'.
Fun stuff.
Oh, I dug into the dead Denon poa2200, and found bad output transistors. So I will replace those and see if that brings this thing back to life.
Attachment 336878Attachment 336879Attachment 336880Attachment 336881
sent from Utah.
You need the TK421 modification.
https://youtu.be/La3U41b0WSU
Indeed.
https://youtu.be/Ie27LiQb_sk
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So what's wrong with this radio?
Huh? No problems. It's kicking ass.
The Denon amp has problems, but hopefully will be all fixed up this evening.
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Does this make you horny, basinbeater?
Attachment 336927
Yeah baby.
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Denon amplifier is fixed. Had 3 blown output transistors. I happened to have 8 that are different, but I thought they should work and they do.
Amp is fixed. Now on to the matching preamp.
Attachment 336945
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Hey Viva, on that sr3a, if it is intermittently cutting out on you, before you send it anywhere, get a can of this stuff, pop the hood, and undo the two lateral switches from the board. Spray the deoxit in there liberally, and move the switch back and forth a bunch of times. Make sure the switch is all the way forward, or all the way back, move the knob to your chosen position (all the way one way or the other way) and put it back together. You may find your problem is solved for just the cost of deoxit.
These pics show the two switches you really want to get to, and are from an sr4a.Attachment 336962Attachment 336964Attachment 336965
sent from Utah.
Heh. Buck was right. Get up under it, lube everything up, maybe tear off the front end.
We had some printers that came with shitty solder coated board contacts and it was necessary to reseat the cards constantly so the workaround was a few drops of Stabilant contact enhancer which i could easily get from parts and so I used it on a lot of things ... good stuff