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Hello, and Help? ;-) SUNN Sorado questions, Tubes, Speakers, Etc?

Hi all, and... hmmm why am I here? Dang, I'm supposed to be outside working, wifey's gonna have my ass (again!). Damn ADD... Well it is useful to a point, allows for "extreme multitasking" ;-)


Anyway, in the endless quest for bass coolness, and tone (comes second), I have been upgrading my bass stuff all year, mainly through a string of good luck (thank you, Bassmaster up there ;-), but none of this stuff seems to do what I need it to do, which is to have FAT, LOUD, CLEAN bass.

Earlier this year, my P Bass was a somewhat gaudy but cool 1989 MIJ Candy Apple Red monstrosity with Maple board, a '57 RI I believe it was, with a Lindy Fralin in it. I magically happened onto a '71 P Bass at a yard sale (well partially, it was a yard sale but it was advertized on CL, for $800 with OHSC, some people are just such ripoffs...), got that (It's awful of course ;-), just the Holy Grail of P Basses I've been looking for my whole life... Sold the CAR MIJ P Bass for $700, not too bad I guess being into the P Bass of your dreams for $100 out of pocket.

Dang, I really need to get outside!


Anyway, at that point, it was time for some amp upgrading. Didn't really even have a bass head, just a '73 Orange OR80 that's I'd use once in a while though an old Traynor 1x15 cab with some old JBL backline speaker, nothing great but sounded ok. I picked up a small head Traynor (OLD!) Bassmaster off feeBay, minty little guy, good sounding too. Then I looked into other speakers, wow... people play through smaller speakers these days, where to find a cab with 10's that doesn't look like a piece of throwaway plastic garbage?

Never did find that, but then I had an epiphany (I have several a day...) What about a Bassman cab with 12's? Different? Bassier? Well, I got a screaming deal on a creampuff off feeBay again (Thx to the crashed economy, it's really great! ;-) A '66 Bassman cab with original speakers, really nice. Wow, what a deal that was. Unfortunately, it's didn't do squat for bass, other than that the small chassis Bassmaster looks really cool on this cab, and whadya know, it sounds pretty creamingly delicious for guitar, the two together.

So I went back to playing the Bassmaster through that ugly Traynor cab (Which I'm thinking I'd be a total dumbass to get rid off, because even though it is a bit big and heavy, it's still the easiest thing I could ever take to a gig if I had a reason to play a bass amp.

I don't play bass, or anything esle in a band, I just like gear ;-)

So, I'm still looking for "that" bass set-up, you know... like a vintage SVT with Silver grille cloth, in really nice shape of course, but without costing a lot (chances of getting hit by lightning are probably better...) and this old '68 SUNN Sorado pops up on the local CL (one owner, bladi blah blah blah) for a grand, and thought about it a little bit, pretty cool looking except for the beer stains and cigarette smoke dinginess...

Time went on and the price went down, at which point I entered into what seemed like endless negotiations (foreplay?) with seller, texts that don't get answered for a half a week, and then the same by myself in retaliation... I had the upper hand the whole time of course ;-)

Eventually I realized I wanted it. No Ampegs here local (The great NW, Eastern WA), and looking through eBay thinking you can get anything you want by throwing a little $$$ out there proved that there isn't $hit out there any more, finding a vintage head and matching cab is harder than it looks, especially in person... and I started making plans to look at this thing, which he said "had it's original Altec speakers"... wait, I'm not sure that SUNN used Altec's and the Sorado cab (ported) is supposed to have "SUNN Transducers" in it, which no one seemed to have been in love with.

God, this is taking soooo long, and I suck at typing...

Anyway, I made plans to get it, $800 cash. I said " Do you have a bass there". He said "Yes, there is a bass here". I got there, there was no bass there... ;-( I didn't bring my P Bass because I learned a long time ago don't take stuff out of your house that you don't want to get rid of, and I figured the jealousy factor upon him seeing the bass would be enough to seriously affect the deal.

Anyway, he had some POS Kurt Kobainish looking Univox Mosrite copy in aged cream color and scratchy pots... hardly what I needed to check the amp out, and it sounded like the speakers were maybe a little frazzled (Gee, who would guess after several decades of rocking out in seedy little clubs), but anyway, everything worked, and it was nice. Kind of a monster cab, very deep really for a 2x15 cab of that era.

Paid and got the beast home (by 11pm... it was actually a bit of a road trip to get this thing), unloaded it yesterday morning, made a spot for it. Later plugged the bass in and tested it some. Speakers do sound like sh*t. A bit distorted when pushed hard, some of it could be the head, but I'm hearing some edge to the notes, especially out of the top speaker that I could definitely do without.

Very touch sensitive set-up, sounds better at low volumes... The p'up in this P Bass is kind of an animal. When I'd gotten it, the p'ups were all the way down to the pickguard with collapsed foam underneath (more melted really...) And I replaced the foam, only to find out that if the p'ups were anywhere near the strings, it would totally overwhelm the front end of whatever head I was plugged into, resulting in unpleasant distortion.

Anyway, the speakers distort for sure, and I'd love to put a set in there that don't. And another part of the problem is not enough clean volume. By the time you get the head to 7 or 8, it distorts also, I'm thinking.

Let me just say; I'm not buying something else, this will have to be it, and it will have to improve, some... at least.

I looked a the tubes this morning, all original... some old GE I think in the GZ position, the 68an (or whatever that is) is a nice looking RCA that looked like it had never been out of the socket, I pulled the back panel in a slight fit of frustration for better access and I could tell by the feel of the screws that the panel had never been off, one can tell these things after years of messing around with vintage gear (and geee guys, what about the placement of that 7025, real clever tucked in front of the transformer on the right side, with a mirror maybe you'd have a chance of getting that back in without destroying the tube...) and the power tubes are a pair of Sylvania 6550, look very nice. But... the tube chart says KT88, and I was up all night... (not really ;-) fretting over this and that, better power, cleaner power. KT88's?

Do you need to rebias for KT88's, and I supposed it was biased for those originally, then 6550's put it biased for those?

Dang, I wish i still had that pair of like NOS USA made Mesa KT88's from the 80's that came out of a West Grande head that I was dinking around with at the time (wanted more distortion I suppose?) They were laying around for a while, and I went into my stash of stuff in a super hurry one day... and one of them rolled off onto a hardwood floor and broke... I could still cry a little (stupidity should be painful), anyway, so I have one KT88, yay....

I suppose I could test this head through my "reference" Traynor 1x15 cab and see what's up. Maybe the head is pretty up to snuff, but it's just the speakers causing all the trouble (mind you, I'm in that super critical phase that we get into when first getting a pice of new gear), I mean, it's not that bad... it sounds nice, there's just an edge to the notes I could do without, and I need clean volume.

The speakers... I'd brought a cordless drill to look at them before buying, but I was going to buy it anyway, and he would't come down on price, at this point there was another guy willing to drive a 600 mile round trip from Seattle to come get this thing the next day... so I never looked at them.

The cab is ported, that you can see from the two distinct smoke stains on each side of the grille cloth. But the speakers have aluminum dust covers like JBL's. Which I'm thinking that's what they are, D140's? You could see the dust covers plainly in his one and only crappy CL pic with flash... and from the research that I did, the "Sunn Transducers" didn't have aluminum dust covers and neither did Altecs.

Another thing I might add (Gee, go figure... ;-) is that when I got there and looked at the amp, I noticed immediately that the back screws on the cab were not only 100% original, which is rare in itself on any old cab, but also looked like they'd never been messed with, in other words absolutely pristine and I didn't feel like taking the back off. I still don't... but definitely will have to and figure out what the speakers are, and then?

Thinking about recone, upgrade, maybe just patch some ripped cone material, who knows?

If I did upgrade, what would I put in it that really stays clean and gives me a nice fat vintage tone?

Should the head have KT88's in it, which ones are the ones to go with, lots of JJ's on eBay at a decent price?

Oh, and another question; The cab is 4Ω, measures 3.6 or something. The head has 2 outs, the regular which is 8Ω but that's the one they've been using all along, and the other is a 4Ω for the Ext Cab out. Which out should I be using? My gut feeling tells me to use the 4Ω out, and that's what I had the cab running out of yesterday when I played the crap out of it very loud for a good half hour. I then turned the amp around and felt the transformer, the one on the right anyway (didn't really realize there were two) and it was barely warm so I figured it's good running it that way. But… it's still a little weird only being plugged in to the Ext Cab out, is this ok?

Well, I gotta get off of here. As a reward, I will get a couple pics up for people to see. So many words... and where the pics! ;-)
 
I just bought a '71 Sorado and it barely starts to drive when the volume is 8-10. I was surprised, really. I think you have to consider having it looked at or have the speakers checked. Or both.
 
If I'm not mistaken, run the speaker out from your the main 8 Ohm jack and then just put a dummy pug in the 4 Ohm jack on the rear tricking the output transformer to run onto a 4 Ohm load?

If you could pull out the speakers and refer to Invalid Link Removed to find out the manufacturer it might help a bunch.

I'm stoked for your find and hopefully it will pan out to work in your favor.

Good luck!
 
"Any time you change output tubes you have to check and reset the bias."

Yes, of course, you're right. Although I've put in lots over the years and never re-biased the amp, mostly Fenders, I never had to do anything to a vintage Marshall or other Brit amp.

Another question, what is that 1/4" jack between the 6550's? Is there a trim pot in there where a tech would set the bias the tubes, or is that wishful thinking?

Is it a slave out?

Well, I wasn't for sure on the Altecs, just the pics i pulled up on Google images didn't show any with aluminum dust covers.

Maybe they are Altecs and are just tired? Maybe they could be reconed to sound great again. Don't know if I'll have time to open the cab today... Wish I had time just to play the thing a little bit.

Don't have time to take pics of the Sorado set-up, but here's a pic of a previous SUNN bass amp I had, picked it up at a yard sale one day on my way to get a couple tubes from the music store. $125 or $150, something like that. Right place at the right time ;-)

orig.jpg
 
If I'm not mistaken, run the speaker out from your the main 8 Ohm jack and then just put a dummy pug in the 4 Ohm jack on the rear tricking the output transformer to run onto a 4 Ohm load?

No, simply plu into the 4 ohm jack. The way the Sunns works is they automatically kick over to which ever impedance jack is being used.

As with any old amp such as this, take it to a tech. It will probably need caps switched out to handle the modern wall voltages, and have the polarity switch taken out of the circuit (less risk of getting zapped, and it'll be grounded). The rectifier tube can be replaced with a Solid State one, which will tighten up the bass response. As far as KT88 vs. 6550, Sunns were initially shipped from the factory with KT88s up until 1969ish, when they switched over to 6550s due to the increased price of importing British KT88s. The KT88s would offer a bit more headroom, but if you're buying modern production valves, the difference between KT88s and 6550s has sort of become negligible. The Sylvanias are probably fine.

The speakers are most likely the old Sunn Transducers, not Altecs. They COULD be Altec 418s or 421s, but that would be extremely rare indeed, a factory special order. The Sorado typically came with the Sunn speakers, which are pretty "eh" sound wise. If not that then maybe JBLs, which would have been an optional upgrade. My Altec 418s have aluminum dust caps, and I do believe the CTS made Sunn transducers had Aluminum dust caps with a hole in the center. If you want to upgrade the speakers, old JBLs are a pretty solid choice (D140s or K140s)
 
many of the original Sunn Amps were made from Dynaco kits. If you have the original speaker cab it probably has JBL (K140s?).

These were some of the best bass available at the time. And they cost.

A buddy of mine was a Mail Man and found someone putting one of these amps and cab out for junk. It might have been a former Four Season.

he still has it last I asked.
 
hey, congrats on the amp. i picked up a sorado and 1x15 about 6 months ago. i've been told it was a '68. have never varified that. it has a 12ax7, a 7025, an ecc83, a 6an8, (2) 6550's and a 5u4. the cab has a reconed d140 in it. starts getting unusable turned up to 7 or higher, but i love this thing and occasionally gig with it.

saturday night, the sound guy asked where to plug in the d.i. cable (while he was looking for an out), i said "you can put it where ever you like, but i don't think it did much good." luckily he had a mic and a sense of humor.
enjoy your sunn o)))!
 
Another question, what is that 1/4" jack between the 6550's? Is there a trim pot in there where a tech would set the bias the tubes, or is that wishful thinking?

Is it a slave out?

You're wildest fantasy has been fulfilled; It's a trim pot.


Maybe they are Altecs and are just tired? Maybe they could be reconed to sound great again.

They might be Altecs, but if so they wouldn't have come from the factory that way. Sunn did custom driver installations (mostly for "name" artists) in those days, and Altec's instead of D series JBL's were one of the more common replacements, BUT...
They wouldn't have done a custom installation in a Sorado, it would have been in a 200S. The Sorado was the "budget" bass rig, about $300 less (about $2K less extrapolated into 2012 dollars) than it's 200S "big brother", and the physical difference between the two was in the speaker cabinet, the amps were the same.

many of the original Sunn Amps were made from Dynaco kits. If you have the original speaker cab it probably has JBL (K140s?).

In actuality very few Sunns were built from Dynaco kits, and the ones that were are pretty scarce today. Those are the top control split chassis models, sometimes called "smiley face" amps by Sunn collectors.
The bulk of Sunn amps were single chassis designs; very similar to the 1957 David Hafler Dynaco circuit, and sharing many components, but not Dynaco manufactured.

As I mentioned above, the Sorado never had JBL's; it was the "affordable" option compared to the 200S and one of the main reasons it was less was because it wasn't available with D series or any other JBLs.

These were some of the best bass available at the time. And they cost.

Yes they were and yes they did. A '69 200S rig was over $6200 in 2012 dollars, and the "big daddy";

DSC00114-1-1.jpg


Was north of $12,500. no wonder that there are so few complete 2000S rigs around now days...



The place to go for Sunn info is the
Link Removed.

All Kinds of good info and basically friendly, truly knowledgeable Sunn geeks there. Kind of slow moving, a lower traffic site, but good solid Sunn info, tech help and history there.
 
I opened the cab at about 10:30p last night, just when i thought I was done... and going to bed, but all the sudden just had to do it... with honey in the background sleepily saying "are you coming to bed?" ;-)

Got the back off, 37 screws I think it was... and lo and behold, were Altecs. The upper is a 421-A that looks like it was reconed in 1999 according to some scribling on the backside of the cone, and the bottom one a newer looking (cast frame) Altec 421-8H, both lok like they were reconed in 1999 and the bottom had a house sticker from ARC, a local place here.

Which is interesting, because I may be able to call him and see what all he knew about this set-up.

Anyhoo, so they are Altecs like the seller said, are they supposed to be any good for bass? I've got my eye on a pair of JBL D140's on evilBay, should I get those, put them in the cab and be happy ;-)

Or keep these, have the top one reconed again (I think it's the one that sounds like crud), or get another matching cast frame Altec for the top position?

Or stick the JBL's in here?


Edit; I'll probably do some troubleshooting today and see what the speakers sound like individually. There's also a couple different Fender 2x15 cabs floating around this area, which I may be able to buy one, IF it had good sounding D140's in it... and then swap speakers out and peddle the Fender cab. A gamble though, as I could just be buying some other fried speakers... and I don't have the room to warehouse another cab, especially one as large as an old Fender 2x15 cab.

I think one of those cabs has CTS's in it anyway, from what I remember reading on the tag, so that narrows it down to one possibility.

There's also another cab floating around these parts with a pair of reconed and hardly used D130's in it, but I shied away from it. And, I probably still would be happier with the D140's, even if just for placebo effect... ;-)
 
I just bought a '71 Sorado and it barely starts to drive when the volume is 8-10. I was surprised, really. I think you have to consider having it looked at or have the speakers checked. Or both.


Ok. Yes, I said that. Then I went and played the amp for a little bit. What I said was true, but, only if bass and treble are set to 0 and the boost switches are both off. Here, very light drive only appears in the 8-10 range.

When you introduce more of the eq knobs the drive becomes apparent. Even as soon as 5-6 on the volume knob.

Just saying'...
 
Whoa... who runs a head on 0 for bass and treble? Never heard of that.

The EQ I decided I liked best with it was around 4 for each, with bass boost ON. I still couldn't get that fat smooth bass tone, that McCartney type sound, and I know it's not the bass. It gets it in an instant on my other set-up, that old Traynor Bassmaster w/ my old Traynor 1x15 cab. The head stays pretty clean up to about 7 then breaks up some. It's just not loud enough to float my boat under 5 or 6, nevermind if I was trying to keep up with drums.

It's a pretty good sounding set-up actually, just doesn't have enough "stage presence"... ;-) That and it doesn't have enough volume or enough bass, but still pretty decent for what it is.

Here's a pic of that stuff, an ugly quickie pic I took to put it on CL...

orig.gif