'70s Ampeg SVT | Diagnosis

[@PsionicAudio]

I said 12AU7 a few times in the video. I need new glasses. This amp has the earlier 12BH7s.

[@goodun2974]

12BH7'S are taller than 12AU and AX7's, should be easy to spot the difference. I think your eyes are tired. Take a little break! PS, I've never worked on an SVT and did not realize they used those telescoping tube shields. Are those stock in this amp? I also have to ask myself why more manufacturers didn't use removable panels so you could get to the component side of a circuit board, other than sheer penny pinching miserliness. Ampeg V series amps had removable panels too.

[@tonycarel1785]

I personally love this channel!! Thanks for sharing your years of experience with all of us. I do wish you nothing but the best in life.

[@PsionicAudio]

I appreciate that!

[@Toymortal]

I think valve amps, especially of a certain vintage, should come with a sticker on saying "WARNING : Do not buy me unless you're prepared to look after me. I will cost you money, but treat me right and I'll reward you with tone!"

[@fiddlix]

I never will forget, back in the day a guitar player that was passing through town (Athens GA), had a Dumble…I forget the exact model but I think it was either a SSS or a Winterland, and was needing immediate attention as it was blowing fuses. So I told him I would take a look at it but I couldn’t guarantee anything. Upon immediate inspection of the amp, I looked in the bottom of the cabinet and it had a SVT power amp. I don’t mean a copy of a SVT power amp. It was a Ampeg SVT power amp with an umbilical cord going up to his preamp section with his preamp section design. Luckily a couple of power tubes and there associated 100ohm resistors is all that was needed to put the amp back in working order. I hear through Bruce Egnater that he incounted something very similar when he had to service one of SRV Dumbles back in the day.

[@ronfrey5327]

sounds more winterland then SSS... if it was 300 watts Winterland. SRV had a Winterland head while 007 SSS was being made so he had a pair of SSS at least one SSS 150 and 300 watts on Tommys side. that would be the cabinet they had to constantly fix the baffle board and speakers and replace screws as the EV 12S would shake the earth and the screws lose every tour.

[@matthewf1979]

Absolutely glorious bass tone out of these SVT’s. I really like the newer Ampeg bass amps too.

[@taraszakordonskk5731]

Do you have a block diagram or schematic drawings for sale for any modern upgrades these 70’s era svts require?

[@crypticdon]

@PsionicAudio I ordered new tube retainers for my old SVT cause they were missing. but i gotta get the screws to mount them, you happen to know what size screws they are?

[@mr.k905]

I wish all amp techs were like you!! Cheers from Berlin/Germany (where people mostly repair amplifiers the McGyver way 🙄)

[@soundcityec]

I have the one with the metal plate and spring retainers. Would you suggest to take them out? Thanks again for all your videos and work!

[@popcorny11]

“10! 10 screws!” Really got me.

[@edwardhannigan6324]

Cool oldie, great info and tips as usual..Thanks for sharing..ED..uk..😀

[@passionplayer7]

Great to see inside the SVT, Bruce Egnater gave a nice story how SRV’s Steel String Singer was the same exact power section when he performed an on site repair. That amp definitely needed some love, thanks for sharing!

[@PsionicAudio]

Yeah, some SSSs are literally SVTs from the PI to the speakers. But Dumble did others that are very different amps just using the same model name.

[@bryanbailey6963]

Just picked one up for fun. Still has a 2 prong convenience outlet on back which dates it at 72 or earlier, from what I read.

[@tedmich]

What a beast! John Chambers has some wonderful stories about working on these!

[@talbotadams1655]

I think I read somewhere that when the Stones toured in the Mick Taylor years with an entire back line of SVTs, they had an Ampeg technician with them throughout the tour.

[@goodun2974]

This story was recounted in the book "Ampeg- the story behind the sound" Those SVTs were early prototypes and not production units. They had 6146 output tubes and the tech would swap the player's cables over to different amps inbetween songs if he saw the tubes start to redplate.

[@jc.1191]

I've got a 67 ampeg Gemini 1 that Keith Richards sold to a shop in Chicago in 73. They were big on ampeg as a group.

[@richardlynch5632]

Nice diagnosis 😎👍 Never have had the pleasure of viewing the inside of a Ampeg like this...pretty cool looking. Can see/hear why these are popular 😉😎👍 😎👍❤🖖

[@BenState]

I love your videos Lyle!

[@charlesjaphe]

Great info

[@Anonymouslives]

Amazing stuff here! You’re like the tube amp pro brother of the guitar luthier here on KZbin ‘Twoodfrd’. Very enjoyable to watch both of your videos!

[@Satchmoeddie]

1970s Ampeg is made by Magnavox, which WAS/is a subsidiary of Dutch Philips electronics company. Magnavox was most famous for making pretty good CRT television sets. Their high end sets were quite excellent for the 1970s. They also made plasma flat screen TV display screens for the US military, in the 1960s. Magnavox started out as Jensen, as the permanent magnet loudspeaker Jensen, Jensen, back in 1911.

[@YTPartyTonight]

The subject of this video is what's commonly referred to as a "Black Line", made by Ampeg in Linden, NJ from '72 to '75. Before that, SVTs made from '69 to '71 are what are colloquially known as "Blue Line" SVTs. Magnavox made American-produced SVTs '76 to '79, AKA "Curved Line", made in Elkhart, IN. One of my SVTs is a '78. Starting in 1980 was the MTI era, made in Japan until 1986.

[@richhillbass]

Excellent video ! Is this amp magnavox era or earlier ? Also in prior SVT vid you mentioned screen resistor memo from company to avoid certain values , which may be a potential problem on new 50th Anniversary Yamaha model ( have 1 and love it ) Wondering if you see potential probs ? Thanks for documenting your work for the world 🌎 to see , I’m hooked !

[@PsionicAudio]

I believe this is Magnavox but I’m not an Ampeg historian. I know the circuits but don’t know all the minutia of various year changes. The screen issue is a long term thing - don’t worry about it while yours is in warranty.

[@PsionicAudio]

And thanks!

[@YTPartyTonight]

The subject in this video is a pre-Magnavox "Black Line" made by Ampeg in Liden, NJ from '72 to '75. One of my own SVTs is a '78 SVT "Curved Line" made in Elkhart, IN by Magnavox.

[@martyswaney1098]

SVT is the Saturn V of amps, it gets underneath and pushes the load wherever you want to go, if you can control it.

[@Andy_Yates]

The Count makes his appearance! 🙌🙌. It also looked like 10 different screws 😬

[@BoarderEthan]

Just discovered your channel and am devouring vids. Do you have any pros/cons that come to mind re: the 80s MTI SVTs?

[@YTPartyTonight]

Very good quality, though some may say otherwise; they'd be mistaken. Their output is known to be slightly less due to Japanese manufacturing sourcing a different and slightly smaller transformer compared to the American-made SVTs that have Electrical Windings or ETC transformers that were made in Chicago. The output difference is insignificant. An MTI SVT is more than powerful enough to cause hearing damage. It didn't stop Dee Dee Ramone from using them on stage.

[@peteloomis8456]

Cool video ! How are the Fender Rock pro 1000 100 watt amplifier heads for quality and sound and are they worth buying or not for the long run ?

[@erajad]

Curious, Lyle - seeing that face plate reminds me of the VT22 I owned back in the 70s (2x12 combo - weighed a tonne). Ever have one of those on the bench? Kind of a special (i.e., distinctive sounding) amp, IIRC.

[@goodun2974]

I've seen a photo of Keith Richards and Mick Jagger in the studio and Keith is sitting on a VT22.

[@JohnCollis]

So cleaning the Tube socket you used Isopropyl. Would contact cleaner have worked just as well? If not what would have been different??

[@PsionicAudio]

You don’t want to leave any contact cleaner in a tube socket, particularly a phenolic socket. Can cause arcing.

[@JohnCollis]

@@PsionicAudio Ahh. OK. Yes, that makes sense. Thanks.

[@goodun2974]

@@therealjustincase , I'm never sure If any given KZbin channel allows links or not and if such preferences are actually set by the content creator; and KZbin tends to "nuke" outside links anyway; so therefore I usually post links only to other KZbin videos, and I will post a comment separately, so that if the link gets nuked the comment will at least stay up. Lyle, whats your policy on links?

[@PsionicAudio]

I used to allow them but I had to go through and manually remove too much spam. With more views come more bots. So I changed the setting, sorry.

[@goodun2974]

@@PsionicAudio , I understand completely. The spam-bots have gotten totally out of control on many channels and I keep seeing the same ones over and over and over.

[@bassplayer2011ify]

As one my friends said in regard to the svts weight "We finally got something big and heavy enough that guitar players won't bother stealing it"

[@goodun2974]

Clean the 9-pin socket contacts with a wound guitar string, .033 to .038, which works like a miniature file or rasp; then re-tension the contacts and flush with alcohol. This process goes really fast if you can find a way to spin the guitar string with a small, low speed/low torque rotary tool like a miniature Dremel or battery powered pencil eraser (Harbor Freight sells a battery powered engraving tool for about $8 which can be adapted so that the guitar string fits into it, and if the clockwise direction of spin tends to unravel the guitar spring ---- why arent they all wound in the same direction?🤔 ---- just reverse the batteries to reverse the motor direction) .

[@jc.1191]

I've used a nylon dental brush I think made for cleaning braces. Dipped in alcohol, works well too.

[@goodun2974]

@@jc.1191 nylon brushes are okay for degreasing and removing dust, but they're useless against oxidation. I've used those dental brushes, and nylon paintgun tip brushes from Harbor Freight, but guitar string is better.

[@johnsimms3957]

It sounds good. I think that IC cap should be changed. Maybe replace all of the electrolytic caps with F&Ts.

[@goodun2974]

The quick-release tube clamps are really nice; I've retrofitted those onto a few amps. They're great for tubes with metal bases such as 6550's but I wonder if they could cause bakelite bases to crack if the fit is a little too snug. Also, not all tubes from a given group or family will have the same exact diameter ---- ie, 6550 and KT88 bases might not be exactly the same size, or might vary from one manufacturer to the next ---- and although you can squeeze the pinched part of the clamp with pliers to snug the fit a little, adjustability is somewhat limited. It'd be nice to find a slightly compressible, high-temperature, self-adhesive felt or foam with which to line the inside of the clamp. Heatshrink tubing might work to snug the fit.....

[@Magikflame]

Do these clamps have a make/model or nickname even? I'd like to find a supplier. Re. your thoughts what immediately sprang to my mind was the type of rubber or polymer that sits in and around the circular clamp around a superbikes silencer/muffler. It ticks all the right boxes for its use.

[@goodun2974]

@@Magikflame , Birtcher Stainless Steel Tube/Capacitor Clamps. I had to scroll through a bunch of "images of capacitor clamps" to find an example. Surplus Sales of Nebraska sells them; now that we know the name of them, we can probably find them elsewhere. Make sure you get the type with a mounting tab for screwing the clamp to the chassis.

[@goodun2974]

@@Magikflame Also search for "capacitor clamp *with release* "

[@weschilton]

That amp looks like King Solomon's Mine. How many tubes are in that thing? I counted 47!

[@goodun2974]

The wiring spaghetti looks more like the Upside Down place in Stranger Things.

[@jeffscarff1655]

47! 47 tubes! Ah ah ah ah!!!

[@oonamorrioghanblackthorne]

I once bought an SVT with the serial number 000128 for $20.

[@bradc32]

built like a tank..i think the only amps i've seen with a high sound pressure warning!

[@johnwilliamson467]

wmf CDE polyester not a big fan on my part . Well they are 600 volt so that helps . Prefer polyprop and polystyrene but that me. I think paper caps are too boutique for me as well as being hygroscopic so not a choose for a dielctric .

[@PsionicAudio]

I like the sound of WMFs. The price and size, not so much. But I also have found that cap material differences affect the sound less as actual capacitance increases unless the voltage also increases a good bit. For example, say a triode has 200V on the plate and the coupling cap is 1nF. I’ve blind tested and heard audible differences between ceramic, polyester, mica, and polypropylene. But if the capacitance is 22nF those differences are much less/negligible. But if the voltage increases the differences become more apparent between different materials at higher capacitances. But I haven’t had time to do controlled testing of this and it’s rare for me to have any circuit on the bench with more than 500V on a cap. So I haven’t quite written any white papers on this, and I have correlation but no definite causation. Perhaps other factors are at play. In general though I try to use the kind of coupling cap material the original amp used at which point the form factor and lead thickness matter more to me (I hate forcing axials in radial locations and vice versa, and I hate caps with flimsy leads). Just shop talk, really.

[@johnwilliamson467]

@@PsionicAudio Well 4.50 each for .047 mfd 600 volt cap is strong for a polyester cap . CDE does make a reliable product with a long life in past I have used the polycarbonate ones . So if you like sound that works given it is a reliable product.

[@jimbeaux4988]

Makes me want to plug in and play som reggae.

[@retread1083]

The silkscreening on the SVT and V series amps has a simple, utilitarian charm. Unfortunately it's also evanescent.

[@imannonymous7707]

The mighty SVT

[@Jonathan_Doe_]

The ironic thing is, a lineman’s splice and some heatshrink probably would’ve been easier than hot glueing that terminal strip in.

[@PsionicAudio]

IKR?!

[@BradsGuitarGarage]

3:00 how the hell do I still have a channel?

[@goodun2974]

Do KZbin channels from Down Under swirl in the opposite direction as they go down the drain? Asking for a friend....🤔🤣 (You definitely do swear a lot, but so do I; I am trying to work up the gumption to post a few techie videos on KZbin myself, and excessive cussing is something I'll have to watch out for. Perhaps I'll make some cue-cards of swear words to keep nearby that I can grab at appropriate moments and show to the camera).

[@stevencraig]

They factor in Geography. Aussie's can't help but swear but we North Americans can help it. On the flipside, I'm Canadian, so my channel would get yanked unless I exceed an apology quota.

[@goodun2974]

@@stevencraig , you can use Harry Morgan/Colonel Potter's approved, sanitized for your protection, cusswords from M.A S.H.: "fiddlesticks", "horse-hockey" or "horse-feathers", and "what in tarnation?!". Do you get penalized if you use too many, or too few, 'Eh?'s

[@stevencraig]

@@goodun2974 M.A.S.H was entirely before my time 😇 but that's a good idea! Yes we are penalized for lack of Eh's, as well as not wearing enough plaid or eating enough poutine on screen. We also get a personalized letter of disappointment from the Prime Minister if any gun safes or cleaning equipment should make it into the frame. For any readers who can't detect obvious sarcasm: I don't really have a KZbin channel and I'm making all this up

[@goodun2974]

@@stevencraig my maternal grandparents were from Quebec, and my wife's mother was born in Grand Falls, New Brunswick (#9 of *18* children, my mother in law is 92 now, the only one left alive, probably because she"s too mean to die). I don't care for poutine, but some of my wife's family in N.B. make a pate' or "head cheese" called "kuh-toh" (a homemade phonetic spelling, probably incorrect) that I quite like.

[@knifeswitch5973]

THE COUNT!

[@HazeAnderson]

viola! xD

[@scottcarpenter701]

lol. bad things.