[AKSA]

Not sure, Phil, it has been written about in the press as I recall.

I would say most would probably be using the 98 RON (Shell Optimax has the highest rating I've heard) for its better idling and acceleration on these high horsepower motors.  I certainly used 98 on my A15 as the superior economy made it viable.

GM have said they've fixed the problem, and it occurred on the earlier engines, going back over a period of almost five years, as I understand.  However, my race car friend tells me that a number of racers are still having problems with the Al block - heat related - and are now beginning to move back to a well prepped iron block, which is cheaper anyway.

Cheers,

Hugh

[DVV]

DVV, I think you are meaning the Holden Monaro, not the Torana...

see here: http://www.holden.com.au/www-holden/action/modeloverview?modelid=12001

Whoops! I stand corrected.

the crazy thing is, you can't buy the normal high octane fuels in Australia, so they de-tune the engines intentionally to increase engine life, hence the proposed Pontiac GTO will outperform the parent car on the street.

Eh?  What do you mean, no high octane fuel? What do you Aussies use for petrol? Over here, on the Old Continent, EC fuel goes 95 or 98 octane old lead type, 95/98/100+ lead-free newer type.

Most newest generation engines require 98 and over, especially those with direct injection, and high compression ratios (11...12 :1).

I thought it was only us Serbs being punished by God to have lousy fuel as we do, we, who just 15 years ago, had by far the best fuel in Europe bar none. It was normal for German tourists to stock up in fuel before leaving the country, not because they were saving, but because they said we had better fuel than they do.

Cheers,
DVV

[DVV]

92 octanes? That's murder on the engine, the poor thing is suffering. We haven't seen 92 in Europe for what must be like 40 years now. In the old days, say 1970, normal was 89 RON, super was 95 ron. Today, 95 ron is normal, super is 98 ron and super+ is 100+ ron. Except in Serbia, where the state monopoly expires next year - we are sold nominally 95 ron classic super which hardly ever has over 92, 93 ron at best, and lead free 95 ron, which is around 93 ron. And people hare are pissed off, but we'll stick out for another year.

You want some rope to hang 'em high?

Regarding engine heat, the only sure way to help in that department, as I have learnt from my ol' Yugo, is to do two things: 1) buy a faster revving water pump and increase the coolant flow, thus increasing efficiency, and 2) add a brand new, sexy looking oil cooler, so you cool the engine from the outside with regular coolant, and with cooled oil from the inside.

I probably have that problem uncommonly pronounced because the block I have was never meant to have more than 65 horsepower (48 kW for Hugh), and it has around 90 hp (66 kW) now and will have 110 hp (81 kW) when I'm done. Obviously, the standard system could not hope,so I did both of the above.

Cheers,
DVV

[EchiDna]

interesting topic that actually touches on my job... I work for a company that runs a few RON and MON engines... basically the test engines that give the fuels the RON/MON numbers you buy at the pump.

talk about old technology, these engines are based on single cylinder tractor engines, effectively run in reverse by an electric motor with a sensor to determine how hard the fuel "goes bang" when compressed in the cylinder... thats how you get the RON or MON number

another aside, the additives that Shell and the like put into their premium unleaded fuels are actually legally required... yet they are marketed as some wonder product that improves efficiency, reduces engine wear etc etc... justifying the extra cost... the additives are VERY expensive, but as a legal requirement, the marketing pitch is absurd!

[jeoffrey]

Aaah Mr Dean,
I was'nt aware that you're that deeply
into autos as well. Looks like we've much
more in common than I first thought.
BTW, that sizzling noise I spoke off has
mysteriously disappered. Any ideas ?

[DVV]

interesting topic that actually touches on my job... I work for a company that runs a few RON and MON engines... basically the test engines that give the fuels the RON/MON numbers you buy at the pump.

talk about old technology, these engines are based on single cylinder tractor engines, effectively run in reverse by an electric motor with a sensor to determine how hard the fuel "goes bang" when compressed in the cylinder... thats how you get the RON or MON number

another aside, the additives that  ...

The ad man speaks with a forked tongue! Not the first, not the last time.

To us low tech types, good fuel is judged by how our car pulls, and if we should hear the valves, well, then we know we've been taken for a ride by some cautios pump man who protects us from mad speeds by adding H2O to the fuel rather than NOS.

But taking the discussion more towards our initial interest, audio, doesn't it make you guys feel sort of warm inside when you HEAR the healthy, gutteral sound of that there engine? Or its angry crescendo when revved at 6,000 rpm or better?

To me, it's "tutta forza Richard Wagner" sort of music. And I have a duette; the little Yugo is like an angry wildcat, small but mean, while the Daewoo sounds like a big, lazy Bengal tiger whose tail I just stepped onto. Different sounds, different thrills, but lemme tell you, sound is half the fun.

Cheers,
DVV

[DVV]

I could be way off line here, but Hugh, have you considered:

1. Producing complete voltage regulation for the AKSA power amp line? I know it's not easy, and not cheap at all, however I think that if done properly, it could bring yet more benefits to those who go for it. Ultimately, one does not need to hog it and buy all at once, this is something well suited for a later upgrade, and

2. You have done 50W/8 ohms (17 dBW) and 100W/8 ohms (20 dBW). Have you considered another 3 dB, or 200W/8 ohms? High power in amps is a very desirable thing, even if you don't need all of it, in addition to opening the door as wide open as it will go in terms of choosing speakers.

I am not provoking anyone or anything, but here, amongst your own users, you can listen to what they say. While not absolute, it is a most useful indication, at least in strategic terms. Even lack of interest is useful information.

Cheers,
DVV

[rosconey]

dvv
ever get a chance to drive a big block mopar(dodge,plymouth,chrysler) or one of the other inferior american brands-ferd,chebby

one of my best friends builds race motors, ohhh for the the sound of 700hp hemi ripping the pavement up .im rebuilding a 62 polara 500 with a 484 stroker and push button automatic, my guy did nascar prototype head development for chrysler in the late 60s early 70s, the big block hey days-he sold me a pair of prototype heads for my motor, a 600 hp street engine on cheap pump gas .in a 3200lb vehicle .

right now the car is in the garage stripped and waiting till i locate a few more parts-then its time to rebuild as a street-pro(pro drive train ,stock appearance)

sorry if this has zero to do with the thread but dvv is a shady tree mechanic  and thought he might enjoy what im doing.

[DVV]

dvv
ever get a chance to drive a big block mopar(dodge,plymouth,chrysler) or one of the other inferior american brands-ferd,chebby

one of my best friends builds race motors, ohhh for the the sound of 700hp hemi ripping the pavement up .im rebuilding a 62 polara 500 with a 484 stroker and push button automatic, my guy did nascar prototype head development for chrysler in the late 60s early 70s, the big block hey days-he sold me a pair of prototype heads for my motor, a 600 hp street engine on cheap pump ...

Yes, I did drive one or two big muscle cars, short rides. Not my type of vehicles, too damn big for my taste. The Plymouth was very comfortable, though, I liked that about it, and this is one of the reasons why I bought the Daewoo. It's sprung on its wheels very much in the American mould, but its size is more managable.

I believe in balance, forever balance. When you start developing any technology, cars included, in my view you need to rework everything on it that is affected by other changes, to keep it all in line. A simplistic example - what use a powerful engine if the clucth can't transfer that kind of power? Or the gearbox? Especially with extremely high torque engines.

This is why I asked Hugh the two questions above. Balance, applied to audio. It seems to me he has developed a nice portfolio of products, and is now possibly heading towards more refinement rather than a slew of new models. Well, I suppose a 200W/8 ohms amp wouldn't hurt, but that's about it.

But the possible regulation - that's simply harnessing all that power, bringing it into better balance.

Cheers,
DVV

[Lost81]

Someone on this (hijacked) thread mentioned overheating of their engine. You might want to try Redline Water Wetter. It decreases the surface tension of the coolant, and improves heat transmission.

http://www.racerpartswholesale.com/redline3.htm

A good explanation of how it works:
http://e30m3performance.com/myths/more_myths1/Water_Wetter/water_wetter.htm

I use it in my Supra...

-Lost81

[DVV]

Someone on this (hijacked) thread mentioned overheating of their engine. You might want to try Redline Water Wetter. It decreases the surface tension of the coolant, and improves heat transmission.

http://www.racerpartswholesale.com/redline3.htm

A good explanation of how it works:
http://e30m3performance.com/myths/more_myths1/Water_Wetter/water_wetter.htm

I use it in my Supra...

-Lost81

Thank you for the info.

You are right, and I am guilty of hijacking this thread. I am now TRYING to get it back to its original melody.

Cheers,
DVV

[AKSA]

Hi Dejan,

You wrote this:

1. Producing complete voltage regulation for the AKSA power amp line? I know it's not easy, and not cheap at all, however I think that if done properly, it could bring yet more benefits to those who go for it. Ultimately, one does not need to hog it and buy all at once, this is something well suited for a later upgrade.  

I did it some years ago, and remember only that it left me quizzical and unsatisfied, wondering where all the dynamics went.

Since giving this more thought, I came to the conclusion that the series pass devices had to be faster than the amp by at least an order of magnitude, that this meant very fast feedback regulation with emitter follower pass devices, and a deal of complexity doubled, one for each rail.  After listening briefly, I realised this would be practical only for Class A amps, and that Class AB would need very careful design.  I haven't revisited it, since the AKSA, with a good supply, excellent caps and diodes, gives such good performance, and the huge increase in actives and passives would more than double the complexity of the overall package - and increase cost way beyond present prices into the realm of unviability commercially.  And say what you like, but DIYers still buy on price - anything too expensive is viewed with interest, but a sale is rarely made.

2. You have done 50W/8 ohms (17 dBW) and 100W/8 ohms (20 dBW). Have you considered another 3 dB, or 200W/8 ohms? High power in amps is a very desirable thing, even if you don't need all of it, in addition to opening the door as wide open as it will go in terms of choosing speakers.

No, I have not built a 200W AKSA, but I have designed one, and two highly motivated customers, one in California, and another in Brindisi in Italy, have actually built them.  Verdict:  Clearly sonically allied to the 100W and the 55W, these amps are not quite as refined, but they do have lots of power and a very nice presentation.  Moreover, it uproots palm trees from desert atolls, and if that's your bag, I might continue with development some time soon to see if I can refine it further.

The problem is this:  the market is limited, particularly as the 100W will easily see 180W into 4R, and the problems in close matching two quartets of outputs cannot be overestimated.   To get a quartet of outputs matched, and matching is extremely important, you need a pool of about 500 devices, and this is labor intensive and murder on inventory costs.  I never wanted to go this route, I can say that, but without scrupulous matching, the sonics are less than impressive.  Multiple outputs are not strictly the way to premium quality hifi, in my view.

On a bright note, it looks as though my 1979 Nissan Sunny has arrived in good shape, though I've yet to see it.  Apparently it was owned by a farmer's wife, bought from new, and garaged all its life.  It needs a bit of work, and the motor replaced, but it's viable and I will look forward to doing the work as I love these old cars.  Very cheap transport;  apparently the body is in excellent condition.  I have a little problem registering the car with a 1.5 litre engine, but with luck the Department database of all the old cars might be out of date now and the A15 engine number should pass unnoticed........  We'll see!

Cheers,

Hugh

[DVV]

Hi Dejan,

You wrote this:

No, I have not built a 200W AKSA, but I have designed one, and two highly motivated customers, one in California, and another in Brindisi in Italy, have actually built them.  Verdict:  Clearly sonically allied to the 100W and the 55W, these amps are not quite as refined, but they do have lots of power and a very nice presentation.  Moreover, it uproots palm trees from desert atolls, and if that's your bag, I might continue with development some time soon to see if I can refin ...

Hugh, I completely agree that a truly load tolerant power amp, rated at 100/180W into 8/4 ohms is all that a customer will ever need, unless he has some really inefficient speakers, which are also a mean load, and he happens to be a headbanger.

I totally agree with your comments on full regulation. May I suggest what I feel is a VERY worthwhile alternative? Split up the power supplies by providing separate rails for the voltage gain stages and the current gain stages. Keep everything as is for the current stages, with only a possible lowering of the rail voltages, since your inherent voltage drops across the transistors will now be lower. Thus, your SOAR is better served.

Then feed the voltage gain stages from fully regulated power supply, say 3...6V above the current stage supplies. This brings many benefits:

1. Better soundstaging, more depth, more detail (possibly not actually more, perhaps just clearer);

2. Improved S/N ratios;

3. Greater immunity from line noise pollution, because any regulation is also a filter by default;

4. Improved stability of the overall amplifier, with somewhat increased real world power delivery into difficuly loads, because the current stages can be run off somewhat lower rails (as there are fewer voltage drops and no need to compensate for them), and in terms of power supply, the voltage gain stage will not even know what the power stage is doing, and

5. In case of overload and possible clipping, it will occur in the current stages, because the supply voltages of the voltage gain stages will still be able to cope. No clipping ever is good, but if it must happen, it's best that it happens as late (i.e. as much towards the output) in the amp as possible, because it will be gentler and recovery will be faster.

In view of the meager current requirements of voltage gain stages, even moderate trannies like the venerable BD 139/140 will do the job brilliantly. Trust me, I have 15+ years of experience with this.

I don't know what your amp uses, but I have predrivers, drivers and output devices. For good measure, I attach my predrivers to the regulated rails as well, thus proving a very stable current drive reference point; this makes for more current delivery into low value loads.

Regarding more power, that was a purely commercial remark. Your comments are about what I'd say if asked.

Just ideas.

If you need any help blowing down the palm trees from atolls, just let me know; I don't mean because of the amps, but because of the atolls, I have a certain weakness for them.

Cheers,
DVV

[Lost81]

Thank you for the info.

You are right, and I am guilty of hijacking this thread. I am now TRYING to get it back to its original melody.

Oh, no problem. I've been there: automobiles can be so addictive...
Wait till you get into motorcycles... They have nutcases here who put turbo hop-up kits on their Suzuki 1300cc Hayabusas  
521 hp @ 16 psi of boost, in a bike that weighs under 465 lbs.
They can perform wheelies in 6th gear...

-Lost81

[DVV]

Thank you for the info.

You are right, and I am guilty of hijacking this thread. I am now TRYING to get it back to its original melody.

Oh, no problem. I've been there: automobiles can be so addictive...

Amen!

Wait till you get into motorcycles...

Not going to happen - I started out from there, didn't like them and am not likely to ever return.

 They have nutcases here who put turbo hop-up kits on their Suzuki 1300cc Hayabusas  
521 hp @ 16 psi of boost, in a bike that weighs under 465 lbs.
They can perform wheelies in 6th gear...

-Lost81

Do they remember to shout "Banzai!" every time they sit on them?

Never mind. I never really liked motorcycles.

Cheers,
DVV