The Last Bass Outpost
Gear Discussion Forums => Bass Amps & Effects => Topic started by: gearHed289 on January 24, 2014, 08:55:19 AM
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Wow, I never knew these things had three output transformers. Not a fan of the folded horn, but this is just plain cool!
http://www.ebay.com/itm/370988628220?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 (http://www.ebay.com/itm/370988628220?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649)
(http://i.ebayimg.com/00/s/MTIwMFgxNjAw/z/QRMAAMXQBlJR-EYW/$%28KGrHqFHJE4FHciL+c%280BR-EYWQ%28,!~~60_57.JPG)
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[jaw-dropping] Gosh... [jaw-still-dropping] ;)
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I saw one of those cabs IRL once in a store. The grill was gone though. Just so massive and impressive looking - I woulda grabbed it if not for the HUGE! God damn having to hump 3 of them around.
Also r right next to it they had a similarly shaped (but not horn loaded? can't recall) 4x12 (Bassman cab I think). I was very surprised at how quickly those got sold (they weren't there more than a week or 2 - I lived around the corner from the store at the time so I popped by on the regular), which was the even more amazing thing.
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Wow, I never knew these things had three output transformers. Not a fan of the folded horn, but this is just plain cool!
They DO NOT have three output transformers. They have three taps on the transformer secondary split from a single primary winding. I HAD one until I sent it away for cosmetic restoration and it, the nice set of NOS GE 6550A's, and the custom roadcase it was in disappeared into New Jersey.
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I saw a head with one cabinet in a pawn shop 35 years ago. The guy turned it on and it started on fire so I never got the chance to try one.
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They DO NOT have three output transformers. They have three taps on the transformer secondary split from a single primary winding. I HAD one until I sent it away for cosmetic restoration and it, the nice set of NOS GE 6550A's, and the custom roadcase it was in disappeared into New Jersey.
Thanks PBG! I was trying to figure out what the third trans would be for :o
Ummm Jersey Devil?
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I saw a head with one cabinet in a pawn shop 35 years ago. The guy turned it on and it started on fire so I never got the chance to try one.
Yeah. They'd do that. The amp runs its six 6550A output tubes so hard that it uses a 6L6GC for a DRIVER tube and has a large interstage transformer, a pretty rare thing for a bass amp. CBS Fender was trying to compete with Ampeg's SVT and Acoustic's 360, and it was probably some marketing "genius" who came up with the idea of requiring three cabinets to get full power out of it- to increase cabinet sales of course. I'm sure the design engineers were cussing them up and down, because making it with a single output like of all the OTHER amps on the market would have done nothing to increase the cost and would have made the amp far more reliable, but once the custom OT was in place, there was no going back. I suppose if you knew how to wind transformers, nowawdays a person could make a single replacement OT for it. If it were a toriod, it wouldn't even be much bigger than the original, but that output stage is VERY unforgiving: Class AB2 AIN'T for the average Marshall or Fender tinkerer.
Fender ALMOST learned its lesson and gave the 300PS, the 400PS's lesser powered successor, a single output, but to save money on the output transformer, that single 300 watt output was at 8 ohms ONLY. Folks who put a four ohm load on it were treated to watching their output tubes literally melt because unlike most other tube amps, the 3/400PS had a supply (HUGE power transformers) capable of delivering the extra current the tubes were trying to dissipate and where they were being asked to get hotter with current instead of being the voltage amplifiers they were designed to be, they overheated and melted their envelopes. The 300PS used a quartet of 6550A's with a 6V6 for a driver.
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Thanks PBG! I was trying to figure out what the third trans would be for :o
Ummm Jersey Devil?
No. It MAY be recoverable, but with my health and employment situation, I've not had the money or energy to chase it.
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That's pretty impressive looking. Tough to find someone local who likes that sort of thing and has the money and space for it. I have no idea what the cabs sound like, but I like my 400PS head. I could live without its bizarre output configuration, but it sounds good to me so I'm happy. At least until the day it needs work.
They DO NOT have three output transformers. They have three taps on the transformer secondary split from a single primary winding. I HAD one until I sent it away for cosmetic restoration and it, the nice set of NOS GE 6550A's, and the custom roadcase it was in disappeared into New Jersey.
That's terrible. Especially with those tubes!
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My understanding on the guy who designed that amp-if you called him up with a technical question about it, he would make you prove to his satisfaction that you were competent enough to work on it, otherwise he would tell you to buzz off, he wouldn't help you. Anybody know if thats true?
Now, if that amp had the kind of transformer that the SVT had-one that allowed you to put the power to one cab-could it have seriously competed with the Ampeg?
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My understanding on the guy who designed that amp-if you called him up with a technical question about it, he would make you prove to his satisfaction that you were competent enough to work on it, otherwise he would tell you to buzz off, he wouldn't help you. Anybody know if thats true?
His name is Ed Jahns and that is true, and I don't blame him one bit. I'm not posting links because the links lead to where my amp disappeared.
Now, if that amp had the kind of transformer that the SVT had-one that allowed you to put the power to one cab-could it have seriously competed with the Ampeg?
Imagine a vintage blackface Bassman tone at SVT volume: that's the 400PS. If it had been equipped with a single output, Fender would have put a serious hurting on Ampeg, Acoustic, and Sunn in the bass amp market.
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So with the three-tap output transformer.... What happens if you only connect one cabinet? Do you safely get one-third of the power, or do you fry something?
Likewise, would two cabinets give you 2/3 of the full power?
(As you can tell, I do not know diddly about output transformers.)
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So with the three-tap output transformer.... What happens if you only connect one cabinet? Do you safely get one-third of the power, or do you fry something?
Likewise, would two cabinets give you 2/3 of the full power?
(As you can tell, I do not know diddly about output transformers.)
I´ve never seen one in person, and was also under the impression that it had three OT´s.
The only info I´ve come across, is from ´the fender amp book´ by John Morrish.
The book has an early 400PS ad, one head and one cab (folded horn, but does not look like the ones in the ebay listing) and here´s the text
below: ´The 400PS was one of fender´s more bizarre efforts. A giant 440W RMS tube amplifier using 13 tubes drove a SINGLE 18in. speaker in a folded horn cabinet of frightening efficiency´
and ´…the astonishing 400PS coupled three separate 145W tube amplifiers…`
I remember reading the ´warning´from the designer, but I never found schematics for it.
Would be great to hear it though, just because.
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So with the three-tap output transformer.... What happens if you only connect one cabinet? Do you safely get one-third of the power, or do you fry something?
Likewise, would two cabinets give you 2/3 of the full power?
(As you can tell, I do not know diddly about output transformers.)
The three outputs are 145 watts each and if unused, like most Fenders of that era, the speaker output jacks short to ground, so you're wearing out the all tubes worse if you only use one output than if you use all three (the supply isn't strong enough to make THAT damage the tubes, but it's still not good for them). It has reverb, too. Fender really tried to throw as much stuff on it as possible, but the output scheme and those big folded horn cabinets which housed a single Cerwin Vega (IIRC) 18" were a PAIN to haul and even harder to hear than Acoustics of similar design. Against Ampeg's smart design, it didn't have a prayer. That's why there are so many old SVT's out there. They sold like hotcakes. I don't like the book overall, but Aspen Pittman's opening line in 'The Tube Amp Book' chapter describing the SVT is, "It's been on as many stages as Shure mics..." Had Fender gotten their act together, they would have had a much bigger piece of that pie.
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It´s not a good book, nor do I use GT tubes - I got the book because at the time I did not have a computer with internet.I do recall them being made at the time, but they were not very common up here in the north :) I spent much time to get schematics for amps, so the collection of schematics was very useful.
Funny thing, I remember a Musicman thread here when I mixed up Leo Fenders involvement in designing the amps; I read some pages of the Aspen book yesterday - and there it was:
´Musicman was started in the mid seventies by some of the ex-Fender employees including Leo himself in a consulting role. However,
Leo had nothing to do with the amp line… `
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I generally like Fender basses and amps, but sometimes they do goofy things, especially when it comes to amps. Maybe if this amp appeared 5 to 10 years before the SVT, it might have seemed like a good idea. But by 1969, you had the SVT, Acoustic 360, Marshall, and Sunn amps. Stages were getting bigger, music was getting louder, and bassists needed to be heard. It almost seems like Fender came up with a good concept, then stacked the deck against it so that it couldn't succeed like the aforementioned amps.
I think it's similar to the Studio bass. They built a nice 200W tube amp into a very large, thin, and top heavy combo. Now, if was never meant to leave home and /or your studio, it wouldn't be a big deal. But Fender's advertisements at the time said you could take this amp to stage or studio, so you could always get your sound no matter where you were playing. I haven't even seen a Studio bass amp in over 30 years, but I remember it being a big, HEAVY amp to move. I notice a lot of people who get them build them into a head format, to make it easier to move. Couldn't Fender have at least offered a head and speaker option when it was new? I think they could have really made a mark at that time with that amp if they did that.
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(https://scontent-a-ord.xx.fbcdn.net/hphotos-ash3/t1/559438_213799332066947_865348314_n.jpg)
Never heard of these. Looks good on paper. Would look better a a head and a cab!
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(https://scontent-a-ord.xx.fbcdn.net/hphotos-ash3/t1/559438_213799332066947_865348314_n.jpg)
Never heard of these. Looks good on paper. Would look better a a head and a cab!
It's the Super Twin, which ironically DID come as a standalone head, without reverb in a combo. The preamp tone stack is a little different, but not much. The Super Twin sounds likes crap for guitar but makes a nice bass amp.
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Not a whole lot of Studio Bass amps around. Best sounding bass amp that Fender ever made and heavy as a tank.
Rick
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I have had a Studiobass for several years, nice amp with tube driven eq. Didn't have as much volume as you would think (my Bassman 100 was loudere) but very nice sounding. The lack of volume was probably caused by the pour room in the speaker cab.
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Great thread. I would be really curious to hear the 400 with some decent cabinets. I wonder what cabs would be a good match for it (aside from the folded horn things... I'm dubious about those).
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I ran mine with three Bag End 2x12 subwoofer cabinets in a homemade SVT cab kinda way. It worked REALLY well.
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Great thread. I would be really curious to hear the 400 with some decent cabinets. I wonder what cabs would be a good match for it (aside from the folded horn things... I'm dubious about those).
After reading years ago what cabinets Psycho Bass Guy used with his, I picked some up for mine. Was only able to find 2 used, I couldn't afford to buy them new. I've used them with a Carvin 10.2 NEO. Sounds good to me and to the people that have heard it, or so they tell me. At practice, I use a Sunn 415M instead of the Carvin. I use the Carvin at home, while the practice space is the only place I have room for the Sunn. I like it better with the Carvin. I also like being able to fit the whole thing in the car.
(http://i.imgur.com/XKWCvkK.jpg)
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That's the best use of a piano bench I've ever seen and if I ever get mine back, I'm using that the next time I have to play with a piano player with bad time (which is most of them).
"Sorry sweetie, you're going to have to stand like the rest of us working folks. Maybe then you'll pay attention to rhythm enough to keep time, and if you can't, I'll turn up."
It is possible to run three SVT cabinets simultaneously off the 400PS. I never tried that. Once life settles down for me, I'm chasing my amp and doing all that stuff..
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(http://i.imgur.com/XKWCvkK.jpg)
Cool. I never thought of using cannabis as a stage backdrop before, good idea :mrgreen:
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Sadly, it was some other variety of weed. Good thing it was there though, cushioned the impact when the drummer knocked his mic off the stage.
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One man's weed is another man's psychotic episode...
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I had a Studio Bass several years back. It was everything said about it here, and truly underwhelming. PBG - your account of your PS400's whereabouts got me thinking - there is probably only ONE place in NJ that someone would send a 400PS for service. Is that where yours got to?
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Yep. And it was delivered by a friend, not shipped, confirmed received, and work supposedly started. I had good contact for about a month, then my phonecalls stopped being answered or returned. I waited a few weeks and tried again,and found out that there had been some emergency circumstances and work would be resuming, then contact stopped again. My health took a major turn for the worse about the same time, so I just let it ride.
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Yep. And it was delivered by a friend, not shipped, confirmed received, and work supposedly started. I had good contact for about a month, then my phonecalls stopped being answered or returned. I waited a few weeks and tried again,and found out that there had been some emergency circumstances and work would be resuming, then contact stopped again. My health took a major turn for the worse about the same time, so I just let it ride.
If you get to the point where you just need too get the amp out of there, and your regular contact is not available, just let me know. That shop is about 1/2 hour - 45 minutes from me.
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If you get to the point where you just need too get the amp out of there, and your regular contact is not available, just let me know. That shop is about 1/2 hour - 45 minutes from me.
It is best not to leave such things sitting too long.
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PBG - your account of your PS400's whereabouts got me thinking - there is probably only ONE place in NJ that someone would send a 400PS for service. Is that where yours got to?
That's gotta be the guy in Union, can't remember his name anymore, been about 6 years since I lived in NJ. He's a total tool, if it was my amp I'd get it out of there asap.
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...bigger fish to fry. It's probably gone.
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A PS 400 cab offered up the road a piece.
http://maine.craigslist.org/msg/5113251270.html
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And a 400 PS head available close to me:
http://phoenix.craigslist.org/nph/msg/5102503503.html
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https://reverb.com/news/the-most-powerful-tube-amp-of-all-time-behind-the-fender-400-ps?utm_campaign=e01aae5a23-rn170502_deals&utm_medium=email&utm_source=newsletter&utm_term=0_5889ed6702-e01aae5a23-57277785
Of course, there are some obligatory "oh my back!" kinda of posts in the comments section.
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The comments about tube history in regards to the 6550A are bullshit, as are the comments about the SVT preamp rolling off bass naturally, and though it's an opinion, I would NOT describe the amp's tone on any channel are particularly "clear." Also, not using an output on the 400PS does NOT put its respective output tube pair into standby, but shorts it to ground.
Regarding the tubes, I knew the former head of QC for GE's Owensboro, KY factory; the 6550A was a US replacement for the KT88, a copy of Sylvania's 6550A, who produced ALL the tube glass envelopes for both companies. GE only made it because the envelopes already existed and they could use-off spec 6550A's, bottle and all, rebased as 6CA7's. The 6550A had more stable screen grids than both the original small bottle RCA 6550 and coke bottle Tungsol 6550, which allowed the tube to be driven much harder for more output power. It was made to accommodate both the burgeoning hi-power hi-fi designs of the day and output power hungry manufacturers like Fender AND Ampeg. RCA, Ampeg's former favored tube maker and neighbor in New Jersey (See the 7027), had already ceased most domestic tube production by the early 70's, though it sold other makes rebranded as its own until the mid 80's. When Magnavox bought Ampeg in 1971 and moved production to East Tennessee, it leveraged its relationship with Sylvania, similarly to Fender's famous "STR" Sylvania 6L6GC's made for the also-mentioned silverface Bassman amps, to help design a higher powered 6550, though SVT's shipped with Magnavox-branded Tungsol 6550's as late as the mid 70's.
In regards to the SVT preamp, a simple perusal of Bass Gear Magazine's curve trace of the SVT preamp set flat shows a distinctive bass BOOST, not cut, or more accurately, an inherent midrange cut that could be mitigated with the active midrange control; the rest of the tone stack is passive.
It's cool to see the 400PS get some press, but though the issues I take may be details, they are important ones.
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Thanks for the clarifications.
It's still interesting to many of us.
(I deleted the rest of my comment about the people on that thread whining about the weight of the amp.)
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I don't deny the article is a long overdue tribute to an often unknown amp, but it doesn't do anyone any favors to spread falsehoods, intentionally or not. Maybe it's the leftover bad taste of my time in TV news and seeing corners cut at the expense of the truth one time too many.
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In regards to the SVT preamp, a simple perusal of Bass Gear Magazine's curve trace of the SVT preamp set flat shows a distinctive bass BOOST, not cut, or more accurately, an inherent midrange cut that could be mitigated with the active midrange control; the rest of the tone stack is passive.
So the bass and treble are passive in an SVT? And as I'm sure you know, the "ultra lo" switch is much more of a mid cut than it is a bass boost.
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I appreciate the clarifications as well, and there are a lot of good points in there, but, I hope you realise that this bit quoted below is a reasonably valid approximation intended for non-techie consumption and not literal interpretation; the point is the given pair of tubes is disabled. Not a literal standby, but not properly 'on' either. Reverb will dumb it down like that and it's not invalid if annoying for those who know better. The rest of the inaccuracies are inexcusable though.
not using an output on the 400PS does NOT put its respective output tube pair into standby, but shorts it to ground.
Again, thanks for the clarification, from those of us who do get the difference.
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So the bass and treble are passive in an SVT? And as I'm sure you know, the "ultra lo" switch is much more of a mid cut than it is a bass boost.
The SVT was one of, if not the, first amps to feature an active EQ. However, it is only in the midrange. All the other tone controls are passive.
Re: "standby" versus ground shorting- that's the most important thing they got wrong. Fender's use of shorting output jacks to protect tube power sections is well known and there's a big difference between somehow idling the tube, like lifting the cathode ground and removing the drive signal (ala Trace Elliot) and conducting its voltage output to ground.