Pioneer Spec 4 Amplifier Part 5 - Final

[@xraytonyb]

Update: After I finished editing this video, I found out that Quick-glo has apparently gone out of business and disappeared. What a bummer! If any of you know of a similar product, please let me know. Quick-glo worked better than any other product I've tried.

[@hoobsgroove]

You might be able of use something like pink for cleaning ovens, it's a paste slightly abrasive like toothpaste even cheap toothpaste might be worth trying

[@Tysman909]

I would try mothers aluminum polish use it on our sleds

[@garp32]

I've had great results on different metals with metal polish made by Wizards. They have a cotton wadding (like Never Dull) and 2 different liquid polish/cleaners. One is a polish and cleaner, the other is a metal protectant which seals against future corrosion. We Wenol is a other cream that many swear by. I really like the Wizards stuff though. Usually available at auto parts stores.

[@AnchorTH]

I just Googled it... The owner of Quick-Glo murdered his wife and father 😲

[@buildstoys]

Been a great series Tony!

[@gime3steps]

Very nice restoration Tony, I've got a Spec 1 and 2, great pointers acquired from your videos, thanks!

[@petertimp5416]

Thanks Tony, Love your work!

[@kevintubbs4648]

Tony, it's great to see someone who enjoys restoring great audio gear as much as I do. I've learned a lot from watching your videos. It's also fun to see how you've arrived at some of the same techniques and methods as I have - it feels "validating." There's nothing like the feeling of wrapping up a long restoration project, and enjoying equipment that looks like new and works like the designer intended. Thank you for taking the time to share all of this with us.

[@RobertKohut]

I just acquired a M-73 amplifier and a C-73 preamplifier (1977-1980 Japan) The M-73 is the little brother to the Spec 4 amplifier (dual mono). Mine sounds awesome, as I expect the Spec 4 does as well!

[@krazytrinisteve]

Omg it 6 am and see this amp woke me up. That is a pioneer power amp and it is beautiful. Reminded me of my childhood using this amp and so many others! Weird child

[@ohmbug10]

Great series. Congrats on obtaining and restoring your dream amp. Enjoy!

[@g.fortin3228]

Wow that one has a nicer took to it than most. I also like the SA-8800 but as we all know the flouroscans will die off eventually. Those meters are here for good. Love it. Nice restore !

[@jaybats7865]

Nice job Tony! Incredible sound! I’d keep it too👍

[@gearheadted9210]

awesome Tony,would love to hear Robin Trower Bridge of sighs on that unit

[@alexzildjian]

Thanks A Lot the vídeo LOVE THIS AMP and learn from You 😊 Hi from Ensenada bajá California MÉXICO 🇲🇽

[@Poppinwheeeeellllllieeeeez]

To say that I am jealous would be an understatement. Rush 2112 would be my first LP.

[@sirsuse]

CONGRATS TONY!! SHE LOOKS AMAZING FROM MY HOUSE! I wish I had a restored SPEC 4. You have made me jealous so I've decided it's tome to rotate my Carver M500t into my main system. I want to watch those big meters bounce to the music.

[@robertduvall7392]

Excellent Tony! Congratulations!

[@mikepxg6406]

I would love to listen to this I bet it's awesome. Great Job Tony. Very Well Done. Mike

[@carlhayes-ze5nd]

Excellent choice on the powder coat finish!

[@jaybats7865]

Amazing amp Tony! The series was awesome, thanks for the fun as always.

[@mfr58]

Great series. A pleasure, as usual. Thanks Tony.

[@ottodydaktyk]

Thanks again, Tony. Excellent job!

[@NICK-uy3nl]

The sound clarity is amazing

[@anandadesilva6558]

A great video Tony. Thanks. As for the faulty transistor (s), it could be one or more of them.

[@jeremiahchamberlin4499]

Gorgeous: inside and out.

[@craigm.9070]

Thank you for your time Tony; this is one of the premiere home audio amps of its day AND today. When properly restored and calibrated...well, you showed it all during testing. Beautiful unit, enjoy for many years to come. P.S. - could you possibly post the powder coat folks you used? They did top shelf work; thank you again.

[@dh-_1011]

Heck yeah. I was waiting for this! Nice.

[@dhpbear2]

6:30 - Tony, the first time I heard that omission of "to be" was on your channel! Since then, Ive heard in on other channels. It most be a Midwest thing! :)

[@Tysman909]

That needle spiking i seen before in my reel to reel ended up being a cap

[@PeterMilanovski]

Tony, I really enjoyed the Bootyfab amplifier series. If you come acrossT any other eBay amplifier (kit or assembled) and decided to have a look at it and possibly see if you can make any improvement to it, I would be watching each episode with anticipation.... There used to be a lot of TDA based amplifiers on eBay, I remember looking at the TDA 2030A datasheet and it had schematics for a powered 3 way design and there also was a two way design in a lesser version of the TDA 2030A although I don't remember which one it was, always wanted to see someone build one but that has yet to materialise.... Looking at the comments section for the Quasi Complimentary Amplifier, I can see that people liked the series... Although I can't compare those comments to the comments from other videos. .. you would know better than me on that.

[@turboslag]

Little tip for refinishing screw heads after abrasive cleaning, use a paint pen. Use a high quality pen, I use Tamiya, and thouroughly degrease the screws so that the paint keys to the surface. Also, use the correct size Japanese ISO screwdriver to reinstall the screws, this minimises damage to the finish. Philips, or even worse, Pozidrive, drivers will chew the screw. If the finish is marked after refitting, just touch up with the paint pen.

[@fr6885]

I use Mothers Mag&Aluminum Polish. It's a mild abrasive cleans and polishes. Cleans up very well also.

[@dhpbear2]

8:14 - A true visualization of *The Magic Smoke* !

[@scrappy7571]

Could you check those transistors with a analog ohm meter? I had a popping noise in the preamp of a Sansui au317. Traced it to a 2sc1775. Swapped in replacements and problem solved. Checking with (2) transistor checker showed the same results you have. A DVOM diode test also showed no leakage, but my trusty 60 yr old Tripplet with the 27v battery showed leakage.

[@iamjezuzchrist]

Wow!! I gotta get someone to do that to mine (powder coat).

[@mikemmikem2758]

After all that troubleshooting all you had to do was tell the meter "don't jump" and bingo!

[@TheTrueVoiceOfReason]

36:52 euphamism! Amazing how so many xsistors could get so noisy. Almost makes you want to replace them on the other side, just for peace of mind..

[@johnnytoobad7785]

Yup..Let's get off the stool and on the pot. I used to stare at the Lissajous pattern on my scope while on pot...🤗

[@Brian-mp6bg]

Great video. Is it possible to run them through your 576 curve tester to see what the problem one looks like?

[@xraytonyb]

Yes, if the 576 did not need repairs 😒

[@andymouse]

Pot ? in the UK your smoking the Devils Lettuce ! Great tutorial...cheers!

[@garygranato9164]

great video , thank you

[@Parkhill57]

I'm wondering if your stereo setup has conditioned AC input? It would be such a waste for the power company to have brown-outs and over-voltages on your valuable equipment. My new HVAC system came with isolation from the power grid gymnastics. Of course it doesn't use the same amp draw as this, so not an expensive option.

[@dhpbear2]

7:07 - Could you *powder-coat* those screws? (I know it's a bit late now :) )

[@scrappy7571]

powder coating is too thick, it will almost fill up the screwdriver slots

[@KathyMclean-tf1tx]

I have been working on a pioneer spec 4 also. Can you tell me if these transistor numbers for heat sink look okay. The gain on a couple is high. Spec 4 heat sink Transistor testing with Peak DCA55. Right and left amp npn 2sd424 hfe=22,28,30,27. Current 2.5ma all, Vvbe .576 to .587. Test current all 4.3ma. Leakage current all 0.00ma. pnp 2sd554 hfe=8,11,58,75. Current 2.5ma all. Vvbe .586 to .613. Test current all 4.3ma.Leakage current 0.00ma all. Does these numbers look okay I have never tested transistors before? Thanks for the great videos.

[@xraytonyb]

In all honesty, I never worry about matching output transistors. I've heard others talk about it, but I have never seen any difference by doing so. Output transistors are mostly for current. All of the voltage amplification takes place in the earlier stages. In addition, it is not uncommon for the NPN and PNP transistors of a complimentary pair to have vastly different HFe at those low test currents. As for Vbe, the differences are taken up by the emitter resistors. If you really want to test power output transistors, you really need to use a test device that can run the transistors at much higher current (amps, instead of milliamps), but it isn't really necessary in these types of amplifiers. Hope that helps!

[@hoobsgroove]

You should make yourself a Carson lab magic probe, exactly design for that purpose to pick up breakdown of components in circuit. you waiver it over the component and it will pick up the breakdown radio interference of the component. Be nice to see somebody build one actually. Hallelujah you coming over to the light side of distortion that's where music is made lol On this amplifier just change the global feedback just put a variable resistor trimmer pot and see where you like it sounding and what the distortion is, it would be a good understanding of harmonic distortion and where the harmonics lie in doing tests measurements

[@davids4610]

What a beauty!

[@PeterMilanovski]

You know, it was a good time to bust out the old signal tracer! We could have heard which transistor was the problem.... I have seen Paul Carlson find a noisy resistor that would have taken ages to find using any other method... And you could hear what sounded like a thunderstorm going on inside. I was calling out to my screen to grab the signal tracer but I guess that I'm too far away and you couldn't hear me...

[@johnm4962]

i have followed your video, but i cant get any bias no voltage at all on the output the amp produces a sine wave but the transistors are getting warm after on a small amount of time do you know what i could look for ?

[@thomaskendall452]

I may have missed it in an earlier video in the Spec 5 series, but how much did the powder-coating cost you? Thanks in advance!

[@xraytonyb]

Chemical-dip stripping, de-rusting, straightening the metal and then powder coating with textured powder coat came to $200. Absolutely not cheap and it better be worth it to you personally before shelling out that much cabbage! While I'm sure it will increase the resale value, I'm not sure if it would by that much. It just depends on the item. This is for my personal collection and I wanted it to look good, which justified the cost to me personally. I won't do this to every project that crosses the bench, but had I known about them at the time I did the SX-1980, that would have been another time I would do this.

[@thomaskendall452]

@@xraytonyb Not too horrible a price, all considered. Thanks, Tony!

[@billmcdonald2436]

The stuff of dreams right there

[@JoeGoesXtreme]

q21 and q19 emitters are connected ogether. Either one of them could be bad and you will see this effects

[@xraytonyb]

Yep, and that's the fun part (NOT) about working with direct coupled circuits like this.

[@hridaydas1446]

Sir, can you create playlists of your video which will make it easier to watch your video series

[@xraytonyb]

I would love to do that some day, but I don't have the time. I would also like to make a searchable list of what topics I cover in each video, but that would be an even bigger task. :(

[@exenx2995]

Tony why did you not tell your viewers the resource you used to have these powder coated ?? You don't mention their name or added a link?? You say if you want your parts done and the quality but you don;t say where or who did them? I don't get it Tony???

[@xraytonyb]

It's called New Image Powder Coating. They are located on Spring Street in Struthers, Ohio. They are a small, local company that mostly operates by word of mouth. They do a lot of work for the local performance auto community. I found out about them through my son-in-law, who uses them for his auto projects. They do fantastic work, but you pay for it. I don't think they have any website or formal advertising. A set of covers like this will cost anywhere from $100 to $200, depending on the amount of prep work and the type of powder coat being used. Depending on the base metal (aluminum, steel, stainless, etc), and the old coating (paint, anodized, powder coated, etc.) the prep could involve chemical stripping, media blasting, grinding or sanding. All of this affects the cost. Only worth it if it is a valuable item or if it has sentimental value to you. Otherwise, sandpaper and rattle cans are your best bet ;)

[@scrappy7571]

Powder coating shops are everywhere. There are 3 within a 10 mile radius here.

[@williamsquires3070]

(@28:15) Of course, if Q19’s emitter is fluctuating, then Q21’s will too, as the schematic shows they’re connected. 🤔

[@dhpbear2]

6:44 - THIS needs cleaned up! :)

[@bitomaxsp]

Tony, what is your primary job/profession?

[@andymouse]

Doesn't 'x-ray' give you any clues LOL!

[@bitomaxsp]

nope

[@andymouse]

He's a Pro Basketball player.@@bitomaxsp

[@erikdenhouter]

The bad meter transistor: already before you replaced the first of the five I would have take my solder iron, and touched a collector for a half second, and wait a few seconds, and do it for all five until the bad one screams.

[@andymouse]

Oddly enough I have just discovered a problem with an oscillator I'm working on by using the very same method !!

[@erikdenhouter]

@@andymouse Do it fast, so the infra red radiation doesn't effect other parts.

[@andymouse]

Yes must be careful with 'black body radiation Thanks !@@erikdenhouter

[@erikdenhouter]

And after I finished the amp, I went searching for a house that fits....

[@andymouse]

Sounds awful !!! On My Laptop LOL! fantastic ! But I agree 0.0000....% THD is probably not correct and I would love to know more about its measurement and why the Kiethly can't measure it, as thats what its for ? and this amp is a great amp but this top end instrument can't measure it ? whats is the point of it then ? I bet that Kiethly wasn't cheap and I would be expecting the instrument to be made for this end of the quality audio spectrum. When you consider there is a 24 bit spectrum analyser shown and raved about on "The Signal Path" for 600 quid I guess the Kiethly is poorly specked for nowadays, do you know what the spec is please....anyhow great series and cheers! EDIT:- just found the specs for the Kiethly if anybody wondered "THD, THD+n, and SINAD from 20Hz to 50kHz with 0.0001% (0.00001 dB) resolution." If the Spec 4 is this good there are gonna be a lot of frustrated Audiophiles out there !!!

[@aminbjt5843]

Tektronix products are very expensive and offer very ordinary features to the customer

[@dhpbear2]

29:54 - I'm guessing it's a noisy resistor.

[@jdmccorful]

I think it sounds clean, clear, focused and controlled. Didn't noticed the level you were running. Another great trip, thanks for your effort and time.