The speakers run on 2-wires, the other 2 are optional for protection and cable inductance for where it matters for long long runs.
Total Harmonic Distortion is given at: <0.007% @ 1kHz., 250W into 8 ohms.
Total Harmonic Distortion is given at: <0.007% @ 1kHz., 250W into 8 ohms.
Last edited:
Hi ZestClub,
Inductance on speaker wire isn't a problem for one. A loudspeaker tends to be inductive, a ribbon often capacitive depending on the type. Your sense lines will cause trouble unless you are very careful.
Is your distortion a claimed value, or a measured value? I am doubtful you actually achieve that with the circuit you have.
Inductance on speaker wire isn't a problem for one. A loudspeaker tends to be inductive, a ribbon often capacitive depending on the type. Your sense lines will cause trouble unless you are very careful.
Is your distortion a claimed value, or a measured value? I am doubtful you actually achieve that with the circuit you have.
Inductance is definitely present in long speaker cable runs (100m+), and it can have a subtle impact on the signal, particularly at higher frequencies.
It's an unavoidable consequence of the physical properties of the cable.
It's an unavoidable consequence of the physical properties of the cable.
Sure you have some inductance, and capacitance too. But not to the level that impacts anything in audio.
People get confused between effects at RF and audio.
Now if you are running 100 meters of speaker cable, I would say you have many other issues to deal with. RF pickup being one of many. At 100 meters, the amplifiers should have been located closer to the speaker systems. You don't normally want to run long signal cables.
We can pick out specific situations until the cows come home. What needs to be done is a properly designed system overall be put in place. Then you can deal with issues specific to your installation and area. With that amplifier, you are worrying about stuff that doesn't matter in the face of other issues.
I'm still on the fence as to whether you are trolling or not.
People get confused between effects at RF and audio.
Now if you are running 100 meters of speaker cable, I would say you have many other issues to deal with. RF pickup being one of many. At 100 meters, the amplifiers should have been located closer to the speaker systems. You don't normally want to run long signal cables.
We can pick out specific situations until the cows come home. What needs to be done is a properly designed system overall be put in place. Then you can deal with issues specific to your installation and area. With that amplifier, you are worrying about stuff that doesn't matter in the face of other issues.
I'm still on the fence as to whether you are trolling or not.
Does Bluetooth go 100 meters?
Put the new amps (Class D, of adequate rating) near the speakers, and send digital signal to each amp.
Power line and other RF pickup will be eliminated.
Since you are in Thigh-land, see if a Chinese supplier of PA equipment will help you in this effort.
Making new amps and putting them in a central location will cause the same problem which you are trying to eliminate.
Here the higher power amps (compared to 1943/5200) use 80N80 mosfets among other devices.
They are used a lot by 'DJ' trucks, basically a 3 ton lorry, with speakers mounted at the end, amps driven by diesel generator, and the music controlled by somebody on the truck, with FM mic for the people who need it.
Put the new amps (Class D, of adequate rating) near the speakers, and send digital signal to each amp.
Power line and other RF pickup will be eliminated.
Since you are in Thigh-land, see if a Chinese supplier of PA equipment will help you in this effort.
Making new amps and putting them in a central location will cause the same problem which you are trying to eliminate.
Here the higher power amps (compared to 1943/5200) use 80N80 mosfets among other devices.
They are used a lot by 'DJ' trucks, basically a 3 ton lorry, with speakers mounted at the end, amps driven by diesel generator, and the music controlled by somebody on the truck, with FM mic for the people who need it.
The emitters go to signal ground. It does go to the cold side of the speakon, along with the feedback/input ground. The hot side is taken from the center tap of the power supply. What is normally the hot and ground are reversed, so the output stage operates common emitter instead of common collector. It simplifies the driver circuitry, as the output stage can be fed directly from an op amp. It requires separate power supplies for each channel. Custom transformer, but in OEM quantity not a biggie. Class H already requires four windings, so let’s go ahead and make it eight! For DIY it sucks (queue the sound of $1000 leaving your wallet via vacuum cleaner) unless you resort to multiples. Separate supplies however, means a fault in one channel doesn’t bring the other one down so the show can continue.
Or you could ask around and find a local competent person, who is involved in this field.
He/ she will know where to find good equipment at low price.
And take advantage of their experience in handling problems like yours.
He/ she will know where to find good equipment at low price.
And take advantage of their experience in handling problems like yours.
I am not running 100m - but the feature is there on the amps to allow for cable inductance compensation for when they are used at a stadium or rock concert when runs could be that long or longer. Those PA companies are experts in that specific field so they know the problems.
No not trolling - the sound system at the moment sounds very good like its a good HiFi level, just more dynamic and impactful. That's because the equipment is fairly top notch: Pro Ribbons, (DAC is a Gustard A26) and in the case of the crossovers carefully custom built with top grade components. I do genuinely want to see if I can take the amps up a notch though and grateful for the help and insight here.
Last edited:
You are correct, the toroidal transformers have 5 secondary's each so total 10 secondary windings in each amp.
How about mixing power transistors from different manufactures?
The Sanken 2SC3263 NPN and Toshiba TTA1943 PNP have very similar specs and also have very good characteristics good Ft and low COB capacitance.
So why are you talking about things you are not doing? For long runs, we use something really cool called a 70 V line.
You can't mix output transistors - or you shouldn't anyway.
You can't mix output transistors - or you shouldn't anyway.
I don’t see any advantage to that particular mix. I doubt it would really hurt anything, but no reason to do it either. There is precedent for having one polarity triple diffused and the other epitaxial planar, so it’s not like it’s never been done. Sanyo used to do that with their “complementary” pairs. And they didn’t match NPN to PNP any better than some of the Sankens that do 60 MHz NPN and 20 MHz PNP.
Don’t get hung up on output transistor Cob on amplifiers with 3 stages of current gain in the output stage. The place where it matters is the first stage! MJE340/350 is not exactly a stellar performer. One could quite easily upgrade those. Hurry, though - the preferred devices are going EOL.
Don’t get hung up on output transistor Cob on amplifiers with 3 stages of current gain in the output stage. The place where it matters is the first stage! MJE340/350 is not exactly a stellar performer. One could quite easily upgrade those. Hurry, though - the preferred devices are going EOL.
Last edited:
True, but upgrading those few things won't buy you anything meaningful. You may well be put in a situation where you need to redo the high frequency compensation.
Good thinking - I hadn't been focusing on that section at all assuming that speed there wasn't an issue.
What would you recommend as a potential upgrade for that section?
2SC4793 (NPN) / 2SA1837 (PNP)
MJE15030 (NPN) / MJE15031 (PNP)
FMMT491A (NPN) / FMMT591A (PNP) - difficult to work with.
Last edited:
Of course at this point it is grasping at straws. Will changing that stage make any difference at all, considering it’s being driven off a 5534 op amp? Probably not. But as a follower, the normal selection criteria is good gain linearity up to the max current that would be required from it (50 to maybe 80 mA), significantly faster than what it’s driving to minimize its impact on phase margin (30 MHz MJE1503x’s), and as low a Cob as practical (to minimize nonlinear HF loading of the VAS). In a normal EF3, driven from a current source VAS - that position with the selected output and driver just screams for KSC3503/KSA1381. It’s simply what I would have designed in…..
That NE5534 is going for sure and it will be replace with a matching opamp for the amps frequency range - likely 627 bass and 828 upper mid/ high.
Looking at the specs for the KSC3503/KSA1381 they look very good.
High Ft and super low Cob.
Looking at the specs for the KSC3503/KSA1381 they look very good.
High Ft and super low Cob.
Last edited:
Op amp swapping is riskier. The 5534 (5532) is fault tolerant. Many “better” op amp are NOT, and if the amplifier misbehaves in any way it can take out the op amp. I’ve blown op amps just from clipping. As long as the input currents are limited by the feedback resistor, 5534’s are known to be able to survive anything that can happen - including having the full + or - 88V applied. Without latching up, too. In the Real World that’s worth soooooo much more than dropping the input noise by a few nV per rt hz.
Alternate op amps might also require revisiting the compensation. Much more so than an improved follower stage (which generally only helps).
Alternate op amps might also require revisiting the compensation. Much more so than an improved follower stage (which generally only helps).
OK, so I could try changing the MJE340/350 first and see how that goes.
And later on, I can fit 8 pin headers for the opamp anyway to make replacement/ future rolling easy.
And later on, I can fit 8 pin headers for the opamp anyway to make replacement/ future rolling easy.
What about the BC547/ 548's ?
They are old stock transistors and idea about replacing them or no point?
They are old stock transistors and idea about replacing them or no point?
They are the device of choice for VAS’s and predrivers. Almost universally used in those single-digit-ppm distortion amplifiers. A lot of designers pissed off that they are being obsoleted.
Of course to get distortion that low requires attention to pretty much every detail, and beyond the capability of this amplifier. Still, good design practice is good design practice. The MJE340/350 were a godsend when the MPSU10/60 disappeared, and the only other option being 2N3439/5416. That old MPSU package was ridiculously fragile mechanically and TO-5’s were a nuisance to heat sink. Technology has moved on, and you can get better than ANY of those old ones now. At least for the time being. I did my lifetime buy of C3503/A1381 back in 2017. 300 each.