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Official Fender 400ps Club

I

IronRadio

Jan 8, 2008
79
2
#1
The Fender 400ps is a brute of a finely designed machine.

Its rated output power is 435W through three independent 4-ohm Output Transformer secondaries but some have been pushed close to 600W in the lab. It runs 700V on three pairs of 6550/KT88 power tubes and when a plug is inserted into one of the three speaker jacks, another pair of output tubes are automatically brought online. Therefore, three loaded outputs need to be connected to obtain full power. If there are fewer than 3 loads connected, the corresponding power tube pair idle with 4.7K cathode resistors.

The worth of a 6550/KT88 is often judged by its performance in the 400ps. Poor tubes will arc, and some have actually melted. Mediocre tubes just won't permit the amp to output its full power whereas excellent tubes will. The best tube for the 400ps is the GE 6550 but they are getting very scarce. Initial testing indicates the repro Gold Lion KT88 works quite respectably in the 400ps.

This amp is rich in history, lore and facts. Much can be learned at:

http://www.timeelect.com/400-PS-IDX.htm

Does anyone else have one of these beasts? I just picked up my third...
 
#2
This little thing? :D

2976227500_ffee2fbdba_b.jpg


Mine needs tubes, but I've been a tad reluctant to lay out the $1200 or so I've been seeing for a sextet of NOS 6550s. I'm keeping my eyes open for a better deal, but have some hope for the Gold Lions... just waiting for someone else to be the guinea pig!

There's a yahoo user group for the 400PS. It's quite low traffic but there's some folks there with a lot of knowledge of the amp, including Rich, who's site you linked to.

Even with sub-par tubes mine sounds incredible. I love these amps.

Of your 3, any or all with NOS GEs?
 
#3
cripula said:
This little thing? :D

2976227500_ffee2fbdba_b.jpg


Mine needs tubes, but I've been a tad reluctant to lay out the $1200 or so I've been seeing for a sextet of NOS 6550s. I'm keeping my eyes open for a better deal, but have some hope for the Gold Lions... just waiting for someone else to be the guinea pig!
Click to expand...

Rich says that his testing of the new release Gold Lion KT88s looks quite good.. for a current production tube...

Of your 3, any or all with NOS GEs?
Click to expand...

Actually I sold my first two after bringing them back to life and am waiting on FedEx to deliver my third. But I hear everything's original in it - so I'm hoping! I ran JJ KT88s in my last two with great results!
 
#4
Good luck with the new amp - maybe you'll get lucky!
What are you planning on running for cabinets?

Nice to hear you did ok with the JJ tubes - did you get to measure output with them, and did you use the heads much after they'd been re-tubed?

This will be a pretty small club, but I know there are definitely a few more guys here with 400s...
 
#5
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It took me awhile to find the right cabs for it. The middle pic, with the 400PS on the right, is the most current setup. I have since changed the casters on the one D12E cab on the bottom so they are now the same height and no longer need the awesome looking white foam spacer to even them out so I can set the Carvin 10.2 NEO on top.
 
#6
Hi Guys-

I've had one of these for 15 years, and it recently crapped out on me. I took it to a very reputable tech, (Bob Dixon at Amphole), and he was unable to fix it due to some really bad work that had been done on it previously. He said that he might be able to resurrect it if he had a wiring diagram showing the actual layout of everything (not just a schematic). Any of you guys have these or know where to get them? I didn't have much luck with the time electronics guy, and besides, I'm in LA. Any info would be greatly appreciated, as I want to get this beast running again!

You know, even detailed photos would help if any of you happen to have one out of the box!

thanks,
Matt
 
#8
Saw another one of these on Ebay for a price I couldn't resist. I'm not a supporting member so I won't mention any amounts, to be safe, but it was less than the average cost of 6 GE 6550As on Ebay - let's say closer to 5, even with shipping.

Old preamp tubes, US and UK make; 5 good GE 6550A power tubes. I have 2 already, so if 1 of those is a close enough match I'd have a set, which I had never even contemplated due to the cost and rarity. Cosmetically the printing is worn, and the tab on the bottom center that keeps you from putting the tube in the wrong way is broken off on 3 of the tubes, which would make the tubes worth less than the going rate on Ebay, since all I've looked at there were pretty nice looking, but I'm not concerned as long as they work, and stay working.

Problem: described as "Working perfectly" in the Ebay listing, it does nothing but hum. Feeble glowing from a couple power tubes. I've made sure it is the amp and not the bass, cab, or cables. Taken off stanby the hum gets a little louder. Any input, any output, knobs at any position. Hit the string on the bass very hard, there's a slight buzz from the head in response. At no point does any sound come out of the speakers. I'm waiting to hear back from the 1 tech in driving distance (he's an hour away) that I can trust, he has worked on my other 400PS. I'd like him to see if it's fixable, before I contact the seller or use Ebay's laughable dispute procedure.

Dilemma: If I win the dispute, I imagine I'll have to ship the amp back at substantial cost. I'll be out a good chunk of change for shipping and have nothing to show for it. And that's IF I can get a refund. On the other hand, I may have gotten a pretty good deal on the very desireable GE power tubes, not to mention the vintage 7025, 12AX - AT - AU - 7, and 6L6 tubes, which would have to go back as well. I may try to get the seller to give me a partial refund since the amp may well be junk, and I can't count on the tubes. My tester is very basic and rates tubes as only good or bad, I can't consider these the same quality as NOS still in box tubes by any means. I hope the tech responds soon, if he doesn't I'll have to do something soon without any professional opinion to guide me.
 
#11
I just got one shipped on a boat from LA to Melbourne, Australia. Flying it would've meant remortgaging the house...
It is the best amp ever and is the truest valve sound I have experienced...
I got a picture somewhere...it's a 71 so it's got the silver cloth...all new GE's front to back top to bottom...full 30-step factory service done to her...any of you guys in LA need this done to yours, give me a yell and I'll find out from the dude I bought it off just who it was in LA who did the service...
Running it at 2/3 thru 4 Eminence 12's paired up in my old 135Bassman 4x12 cab and it absolutely rips your head off at barely idle speed...I had an SVTII for years and this monster outdoes that with ease. I am considering transfering ownership of it into a buddy's name so if my wife and I ever split up - she can't claim it!
 
#12
Cool. My nonfunctional one has the silvery grille, looks better than the black my old one has. I do prefer my old one sonically, not a fan of no sound at all.

IronRadio - I'm in New England. Waiting to hear back from my tech, soon I hope. It's a dilemma, as I'd rather not have to send those tubes back, but I don't really know how much life they have left in them. From what I've been told the transformers are the only things that can't be rebuilt/replaced. If I don't hear back from him soon I'm going to have to flip a coin.
 
#14
Wow, I guess I didn't get a notice on this in email. Anyone still have photos or lead dress? Thanks for all the help, sorry I wasn't around to take advantage of your generosity. I bought a Mesa Boogie, but I still want to get this baby running!

Matt
 
#19
nomaj said:
How would you describe the sound of the 400PS vs. an SVT? Do you still gig with it?
Click to expand...

I can compare the sound of mine to the sound of an SVT2PRO I owned at the same time, but played through different cabinets. When set as close to perceived "flat" EQ as possible, the 400PS sounded clearer, crisper, and deeper. The old fashioned EQ is not as flexible as the complex EQ + graphic on the 2PRO, but still capable of yielding a variety of tones, as long as they are clean tones. Distortion is pretty much impossible on the 400PS whereas the 2PRO has some glorious distortion if you want it. 400PS loves my downtuned 5 string.

Reverb and Tremolo on the Fender are much better since @PRO does not have them. Limited usefulness on bass, but makes you wonder how a Strat or Tele might sound through 6 guitar cabs...
 
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#20
I do play out with the 400 PS. While I own an SVT, I've never played through it; I inherited it when we lost my oldest son. It lives at a church where the bass player uses it to make a joyful noise.
I do use an Ampeg V4B some, as well as a '70 B-15N in the past, bought new and currently DOA, but I'm not particularly good at describing tone. All are different. When all three outputs on the 400 PS are hooked up to 4 ohm cabs, it can really shake the world, and I sometime slip in a wee bit of reverb. I'd love to have a 1/3 powered version of the 400 PS in a much smaller package to use with a single Barefaced SuperTwin. Someday, someone will build one.
Tim
 
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