Marantz 2252b Part 6 Final With One Last Mod

[@manuelgalvan1701]

Hi Tony, I have been watching your videos lately since I have a Marantz 2252B and I am the only owner. I don’t know much of electronics but I have an idea. You do a very nice work on the equipment you restore or repair. I have watched most of your videos. Very professional and fun. I am from Mexico and live in a small town now. It is still working but as I have seen on your videos a service on my Marantz will be a good idea. But I can not find a technician nearby that works on vintage equipment. I will keep looking but your videos on the Marantz that you worked on will be very very helpful. Thank for your good work and your videos!

[@pybelleau]

The most effective way to learn something is to work with someone who has a lot of experience, searching in books is often very inefficient and you often get an incomplete answers. Great video.

[@Alextheampguy]

That amp went from good to mindblowing 👌. Good job Tony!

[@pauldavis6356]

The audio demo came across the web sounding very nice. Listening with headphones the sound was very clean and I was surprised at the richness of the low end. Nicely done Tony.

[@milehighed52801]

Thanks, Tony! Good stuff. I owned a Marantz 2220 about 50 years ago. It was my first receiver. I should have held on to it in hindsight. Can’t wait to see more!

[@craigm.9070]

Great video series Tony! Thank you for your time.

[@radio-ged4626]

Great result. I've learnt so much beyond the basic maintenance and repair. THD is not something I can measure but using a scope and recognizing what is Miller effect and how to go about correcting it and also the likely causes of clipping. These are things I can take forward. Thank you.

[@mjg263]

What a great series, I’m going to refer back to this one from time to time. Thanks very much for all the effort!

[@Traci_S_Aaron]

I think Tony has earned the cookie and glass of milk for this one You're doing just as much engineering work as you are a technician

[@rossthompson1635]

Thank you for this excellent video series. The Miller capacitor and resistor modifications were very interesting and made significant improvements.

[@JamesE707]

Hi Tony, It does amuse me when some folk get concerned about ~0.1% THD. The truth is, we'll never hear it - one good reason is that our loudspeakers and headphones have an inherent distortion figure much higher than 0.1%. I like the way you slowly inch your way through these repairs - indeed, not to be rushed! Fine work sir!

[@xraytonyb]

I agree. In this case, however, it was an indication that the amp was going into oscillation. It was at high frequency and hard to see on the scope. The only clue I had at first was the higher than expected THD. Some of my favorite sounding amps were from the vacuum tube era. They had THD figures over 1% and I still loved the way they sounded. Your ear is still the best test equipment. ;)

[@mistermac56]

@@xraytonyb the late Julian Hirsh with Stereo Review magazine always made a big deal about THD when he rated receivers/amps and would poo poo a great product because the THD was higher, when he would give rave reviews for a so-so product because it had great THD. You can't judge a great sounding product by test results alone. Hirsh was often called out by readers and other reviewers at Stereo Review. As you said, vintage vacuum tube devices sounded great, but had inherently 1 % or more THD.

[@JamesE707]

@@xraytonyb Can't fault you at all Tony. My amusement was never directed at your video, just that those who are impressed by the 'reviewers' in various HiFi mags get taken for a ride every time. There's a lot psychological self kidology too at work. Yes, I too am impressed with '0.01%' and lower distortion figures, but I have to sober up and tell myself - Eric, you will never hear it!!! ;o)

[@fireantsarestrange]

Very nice old tuner. Wish I had that. 24 years ago I wouldn't have blown fuses in my Cerwin Vega's.

[@TrevorsBench]

Great job Tony, looking forward to part 7, lol

[@xraytonyb]

I'm happy to announce that this one is off the bench and the next project is well under way :))

[@garygranato9164]

the flute was nice background music :)

[@anandadesilva6558]

Great as always! I am surprised at the sound quality even with all the losses of doing a recording like this. Your explanations are also much appreciated. Thanks Tony.

[@xraytonyb]

I have a really nice digital recorder and for some reason, this silly little clip-on microphone does just as good of a job (but just in mono instead of stereo). The biggest advantage is that it is simple to record the amplifier while I'm making the video, without any special setup.

[@anandadesilva6558]

@@xraytonyb very interesting!

[@Amplified208]

Sounds wicked. And like always professional.

[@BrendaDiana-b6g]

The flute sounds good!

[@mikepxg6406]

Fantastic job Tony. Thank you.

[@markanderson350]

If fixed amps as a teenager along with cb radios and who knows what else, was the 70s. I had little equipment and i just went for voltages. I knew exactly what crossover distortion sounded like. Wish i knew of dim bulb testing.then. I called it balance and bias. I just hoped nothing blew up. Only used a meter.

[@poormanselectronicsbench2021]

Thank you for testing my suggestion of making the THD meter a more direct connection. The difference wasn't huge like you mentioned, but it was noticeable, and sometimes progress is made with baby steps instead of leaps forward.

[@vertoboy]

Tony, I hope you did bias adjustment after increasing the resistors values cause it would go way up. The "positive starving" issue could be better resolved by current increase from the bootstrap circuit R724, R726, C710 (lowering the resistor values). The stock bootstrap configuration provides less then 5ma and I think this is too low to drive the positive side when using low gain transistors.

[@xraytonyb]

I'm glad you brought that up. That was the first thing I tried, but I was unable to get a combination that would give enough swing in the VAS stage without affecting stability. One thing I didn't try at the time was C710. That may have been the reason I couldn't get it to work. As for the Bias, it barely affected it at all. The voltage across the output emitter resistors only changed by about 2 millivolts. Outputs are running cool and drivers are running cool at idle. Thanks for the comment! I'll remember about that capacitor on the bootstrap circuit next time!

[@iamme1178]

@xraytonyb what is a "Maeantz 2252b?" is it a dollar store branded knock of amp ;) Keep up the good work and thanks for doing these great vids!

[@xraytonyb]

First I have to fix the receiver, now I have to fix the title. What next ;)

[@johnnytoobad7785]

A re-built Marantz unit by Tony is called a "Maeantz" (pronounced Me-ants) . You should make up custom nameplate labels and attach them to your mods.

[@Silent-Lucidity]

Ah, a Sunday evening episode!

[@tonylenzi166]

I had this reciever, i bought it for 35 dollars at a thrift store, it worked but the left channel was very scratchy go off and on, i ended up selling it for parts on ebay got 400.00 dollars for it for parts, but ill tell you what, i regret it, that thing sounded good, and was powerful, i had an adcom 250 ×2 amp witb the pre amp tuner all that good stuff, that sounded nice, but imo the marantz killed that adcom as far as sound quality and power, im def gone be getting me a rebuilt one one of these days

[@ryanhoward6623]

Where do you sell the amplifiers at? This was my amplifier at one time. I acquired it through a large trade of equipment and most likely some records. I never got around to messing with it and am glad I did not… that was very impressive. Over a year passed and Dave remembered to send me the link to video. Great stuff! Let me know if you want a real nightmare… I have a 9099DB that needs to bypass the DB board…? Thanks again! 🍻

[@xraytonyb]

Thanks for the comment! Most of the equipment I restore goes back to Dave and he sells it. I really don't like shipping/selling stuff because it is a huge hassle for me. Dave doesn't mind doing it, so I give everything back to him. If you reach out to him, he can help you out.

[@chekegiceman4030]

Hey Tony, I just wanted to ask if you could tell us where to buy resistors and other components. Thanks

[@xraytonyb]

I purchase mostly from Mouser and Digikey

[@TwinGunz]

Marantz is spelled wrong in title. Use to have one of these, nice piece for sure, very bright sound.

[@xraytonyb]

Fixed the title. Thanks!

[@davidlane5381]

What capacitor or resistor do you use for tone or bass gain in a receiver or record changer?

[@chekegiceman4030]

I have a pioneer sx-880 that I want to recap as a learning project and I don't know if I should buy a kit from ebay?

[@xraytonyb]

I don't buy them myself, as I don't know what parts they are using or where they got them from. I'm sure some kits ar eperfectly OK, but you would need to do some research to see who's reputable.

[@paulluke-w8p]

Typo on the cct diagram R761 and R728 have different values ,should be the same for Right and Left Chns.

[@xraytonyb]

These schematics had several typos. Marantz and Sansui seem to do that a lot with their schematics. You really have to watch.

[@ДенисСоболев-э6р]

Beauty!

[@erhman2004]

You have a typo in your title of the video. Just so you know. It can happen. The "e" is next to the "r" on the keyboard.

[@mitkothemacedonian]

1/4W 180ohm would have been just fine.

[@brotherbrian5625]

So is this a class A receiver? Or is it a Class D?

[@xraytonyb]

The output section is Class AB push-pull. The voltage amplifier stage is class A and the driver section is SEPP (single-ended push-pull). I know it can be quite confusing, but amplifiers are classed by the output stage design (in this case it is AB) , but they will almost always have a class A stage at the input. Class D amplifiers are very similar. The output stage is class D but the input stage will often be class A (even the ones with OpAmp inputs will have a class A stage inside the IC. Hope that helps.

[@brotherbrian5625]

@@xraytonyb very helpful Thankyou I use to have this receiver and the best thing I liked about it was the smell 😂...it reminded me of going to the audio stores back in the late 80's. I have some Sun Valley Marantz that I like the sound better. But these Japanese ones are beautiful...Thanks

[@jdmccorful]

2nd test was real good on bass. It was tighter and more focused, at least to my ear.Really enjoyed these 6 visits teach! Thanks for the listen and demonstrated techniques you use.