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camusmuse 5th September 2005 05:22 PM

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.....

Perry Babin 5th September 2005 09:11 PM

I may have a schematic for the Autotek 44/66/99. Do you know if the BTS amplifiers that you have are, in general, the same as the Autotek 'Mean Machine' amps?

I know that the 7040BTS is different (TIP142/147 instead of TIP35/36 for outputs) but I don't have any of the larger ones here to look at.

camusmuse 5th September 2005 09:41 PM

I'm pretty sure they are different. However if its not too much trouble I'd like to see what you have to see what sort of changes were made. I have a few of the Autotek BTS schematics, if you want a trade.

MOER 5th October 2005 05:26 AM

Old Hifonics and Autotek amps
I designed and manufactured all those amps

Give me call at the factory and let me see what I can dig up

Stephen Mantz
Zed Audio

(805) 526-5315 PST

camusmuse 9th October 2005 03:21 AM

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

MOER 9th October 2005 05:11 AM

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

sdoom 9th October 2005 08:33 AM

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.

Id 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-


MOER 9th October 2005 05:20 PM

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 ( 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

sdoom 9th October 2005 08:13 PM

Hi Stephen

Thanks 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 Im getting older and dont 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 ?

camusmuse 9th October 2005 10:13 PM

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 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.

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