Hifonics Service manual / schematic

I'm looking for any info on the old Hifonics series IV, V, and VI amplifiers. Specifically for the Zeus, Thor, and Odin models. I have several that are in various states of disrepair, some missing parts, so the parts lists and schematics would be great if anyone can point me in the right direction. BTW I'm also looking for repair info on the old Autotek BTS amps, as I have several of them as well. Thanks.....
WOW! Its great to know that your on these boards Mr. Mantz. I actually emailed you a few months ago with the same request and you replied that these schematics were no longer available. I'll still call sometime just to be sure though. Plus I want the skinny on the new tube amps you mention on your web site. I'll definitely be a customer for at least a pair of amps. Serial #1 and serial #2 available? :D
Hifonics and Zed Audio

I do not believe that we have schematics but of course I am able to help either doing the repairs or offering advice

Still busy deciding what format of tube amplifier to build and how many channels. I wnat to go full tube all the way to the ouput stages and then use BJTs for the outputs - I am not a fan of Mosfets for audio


Stephen Mantz
Zed Audio

Zeus Ser.8 (blue) repair

Hallo Mr. Mantz,

it is an honor to see you on the board and I was really impressed to recognize that you are still with us, the customers. Today most companies have nice looking products , but the companies cannot identify themselves with the customers.

I´d like to ask a question about a Zeus (Ser. 8 , blue heat sink) repair. On this amp there are severall transistors burned . I could find and get most of them till now, but I cannot get the MPSA12 transistor (The owner of the amp broke one transistor when he disassembled the amp). As far as i can see those transistors are darlingtons and are connected to the BIAS+ ans BIAS- pins so I assume those transistors handle some part of the idle process.

Could I use a BC517 instead (the current amplification factor is only 10000 instead of the 20000 ´s MPSA12) and how would i have to adjust VR101 and VR201 ?

Thanks for any help-

Hifonics and Zed

Dear Stephan,

The MPSA12 is indeed a darlington. You can use any small signal darlington to replace it. The current gain is not that important.

Be sure that whatever device you use does not have any built in base-emitter resistors. Also make sure of your pin connections are the same.

It seems funny that you cannot buy the A12 in Germany as it is a common device made by several companies.

Once you have the amplifier up and working, drive it with a 20KHz sinewave into a 4 ohm load at about 1 watt (2v RMS)

Set the gain anit-clockwise to minimize noise. Turn the trimmers on the PCB anti-clockwize as well.

As a safety precaution, insert a 2 to 3 ohm power resistor (20-30w is fine) in series with your +12v lead. This will prevent any smoke and fire if there is anything wrong and I recommend this procedure when first turning on any amplifier as it saves much heartache later on, nevermind more repair work.

With the small amount of power this power resistor will not affect things much.

Now observe the sinewaves on your scope and you will see the crossover notch very clearly. Set each trimmer so that the notch just dissapears. Now check the voltage across the MPSA12 bias device (Coll-emitter) and it should be about 3.3v DC.

If it is higher than 3.3v back the trimmer down. Quite honestly if you see a"tiny" bit of crossover notch on the scope, I do not believe it is audible (Proof over all these years nobody has ever complained and Zed has built hundreds of thousands of amplifiers). This ensures complete thermal stability of the amplifier.

Some years ago we did a test at one of the top German car stereo magazines in Studdgart. We compared a series 7 Zeus, a Series 7 Cupid (22w.ch) against a "class A" Alpine amplifier rated at 65w/ch (which I did not believe then and I do not believe now as a 65w/ch pure class A amplifier typically will dissipate 650 watts of heat continuously) Anyway I think that it was just a hard biased class B amplifier, no more no less!

The tests were double blind and the best sounding of the three was......the Cupid (Power notwithstanding). The Zeus had the most dynamics. Noone could hear the "notch" which was always present in all the amps we built!

So with all that said, I recommend that you back of the trimmer just a tad so that you can just see a little notch on the 20KHz waveform.


Stephen Mantz
Hi Stephen

Thank´s so much for the description on adjusting that huge baby. I will try to install the BC517 next weekend when I ´m home.

And yes some transistors are hard to get overhere. I was looking for more than 6weeks to get the SGSD100 . Audiodesign told me to replace the SGSD100 with a self made darlington (TIP102+TIP35C in series) . But I think that is not a good idea as only one transistor would fit beneith the heatsink and there would be no heat coupling. I got the SGSD from a broken Concord (Harman) 4 Channel Amplifier with a broken SMPS.

I think the series 8 amplifiers are real mean machines. I used a small pluto to drive my door speakers and the small amp deliverd more than good results.

May I ask another question. A couple of years ago I purchased a Gen X Series Zeus , still have that thing, but it is in the glass cabinet because I´m getting older and don´t have 15" in the trunk anymore :clown: .

Did you design those amps, too or are those already Audiodesign/maxxsonics amplifiers from Korea?



PS: Do you have a picture of the inside of your Leviathan ?
Mr. Mantz

WOW again! Thanks for the repair tips, thats exactly the kind of support I need to point me in the right direction on my amps. Unfortunately my "workshop" is "storage" now and not set up, plus I'm still recovering from an auto accident a few weeks ago. But hopefully I'll be back on my feet soon and at my favorite place....my workbench.

Why are you going to use sand(BipolarJunctionTransistors right?) for the outputs of the tube amp? Why not just go tube *all* the way. I have always wanted to attempt an 6550 PP (ST-70ARCMod)based car amp. I imagine that the power supply will be the big hang up in the car though. But first I'll try to pull one off, or maybe two(grinning), for my home setup.
Zed and Hifonics

Dear Stephan

Yes I did design and manufacture the Hifonics Gen X

Sorry protos of the Levathan are not complete

SGSD100/200 may be raplced quite happily with a TIP35/36C and a TIP102C/105C in a made up darlington. The smaller TIPs do not need any heatsinking. We used this configuration before we cxhanged to the SGSD100/200 types


New Zed amplifier

Dear Camusmuse,

A full tube amplifier limits me in power and the output trannies are expensive. I have considered an OTL circuit but they are just too big and too many tubes needed.

The power supply is NO problem at all. I have 30 years of SMPS experience and we build very reliable supplies.

Guys want lots of power, even with these "tube" amps so hybrid is the only way to go


I would agree that your smps curcuits are very stable and ,more important, they are strong ! I remember my GenX zeus burning 80A fuses (slow fuse) when driven hard , but the amplifier never failed, replaced the fuse and the baby was back to life.

So far , from what I ve seen ( I fixed a lot of korean standard amps , most of the times made by KIA) , almost all amplifiers with a burned fuse had a faulty smps (most of the times burned FET´s).

From the Hifonics amps , I had to repair in the past there had been only one with a faulty SMPS (and I´m not sure what the guy did ).

I assume that if there were only tubes, a lot of power would have been "wasted" for heating all the tubes.

What I´ve always been wondering is why amps aren´t build in some kind of "stack" , meaning if you want / need more power you add more units (like linking two "son of colossus" to double the power).

Wouldn´t it be possible to use one amplifier for the pos. halfwave and the other for neg. halfwave ?


Ahh but Mr. Mantz has done that as well, with the amps he made for ESX(I have a few of them too). You can hook identical amps together and use them as one amplifier.

I was actually hoping that he would make the tube amps that could be configured like that as well to up the power some for the waveguides I want to use in my next system. Until then I'll probably use a 7300 BTS for EACH waveguide/8"Vifa midbass then use my 7600 BTS for the subs.... ah now if i only had a car to put allthis stuff in....lol.
Paralleling amplifier channels

Yes we did this in Hifonics Gen X using the "POS" card and we did the same thing in the ESX amplifiers using relays.

We simply took the output transistors from one channel and electrically "moved" them to the master channel thus doublijg the output capability. This is not as easy as it sounds as the unsued channel must still be kept stable since it now has no output stage.

The electrical movement also CANNOT be done whilst there is power applied to the amplifier.


Stephen Mantz
Zed Audio
questions about the different colossus generations lines

I have a few questions concerning hifonics…

What was the last series (of the colossus line) that was made by the original founders (Stephen Mantz & or
Zed Audio) of hifinics before maxxsonics bought it…

Wich one’s are better… the old school colossuses (VIII on down) or the Generation XI colossuses or the Gen XX colossuses?

I have a Gen XI Class AB colossuses & was just wandering which one was better… I’m kind of scarred of the maxxsonics versions of hifonics because I bought a Zeus ZX6400 & was dissapionted… and replaced it with a PG Xeon X200.4

I thought the Gen XI colossus was made by original fouders, but it may be a maxxsonics product… But it doesn’t say maxxsonics any ware on the amp or on the internal board… My “hifonics” lettering are chrome & don’t light up (like the maxxsonics one’s)


Zed Audio

The Maxxsonics amps are from China/Korea so I leave it to your imagination what their quality is like.

The last Hifonics which Zed produced was Gen X, this was produced for them when Matt Coleman "bought" the compnay from the original owner, and then some years later when that went belly up this crowd at Maxsonics snatched it up.

Our new amps which we make under our own name and sell direct are far superior to anything I have designed and built in the past as we had few financial constraints in the design


Stephen Mantz
Thanks for the info & the link… I seen that link about 6 months ago… I pass it up because I didn’t see anything big enough for me… I was looking into the 1,200 min r.m.s. – 3,000 max r.m.s. watt range (in the THD 0.08 – 0.03 range)… or as big of an amp for $1,499 could buy from u guys. I just like the colossus design because it’s a big 2 channel amp… that the stereo channels could load down to 1 ohm… and 2 ohm mono… (with a regulated power supply)