syn08 said:
While that may provide rock stable voltages to the devices, it does not address the issue of current path control.
I surmise Johns "fix" is probably better than what you are thinking of..
Cheers, John
jneutron said:
What I said has nothing to do with the current path control and magnetic effects, but with the xtalk and multiple power supplies.
syn08 said:
Methinks John feel the same way.
It's just so strange to hear everybody talk about moving signals around willy nilly, without worrying about where the current is actually going..the path it takes...
Just because a signal is e-shielded doesn't mean that it does not have an external magnetic field. Just because you put a shield around a coax, that still doesn't guarantee the shield current is equal to and opposite that of the signal..especially when the shield connects to something at both ends...
In the conversion from tubers and high Z..... to zistors with low Z, magnetic field and induction has been a lost child..
Weird..
Most people still believe they can get a 50 plus watt 4 ohm load resistor that is accurate at 10 kilohz...
We got a long way to go...🙁
Cheers, John
john curl said:
From my experience grounding directly affects all of these.
The most sophisticated power supply circuit will not perform well if the ground reference is noisy. All it takes to add noise on your supply reference (or for that matter any gain stage) is a return path, for any of the multiple loops in the circuit, that follows the same path as the supposed quiet reference's. This is where the discussion of unintended paths becomes relevent.
Mike.
jneutron said:
I'm not debating the magnetic effects in power amps. God knows, I sweated blood around such issues in the PGP amp.
Ground loops are important for both avoiding magnetic fields (through uncontrolled current paths) and xtalk issues (through sharing finite impedance paths). Of course, they have a common physical root (current flowing paths) but unfortunately IMO they can't always be addressed by the same countermeasures.
Example: you can't avoid current flowing through supply wires, and even if you cancel the magnetic fields by running the return path in parallel, this would help squat for crosstalk issues, 'cause the finite impedance path is still there, shared by the gain stages. It's electrokinetics vs. electrodynamics.
syn08 said:
It is not necessary to avoid magnetic fields. Nobody's said that.
What is important is to either eliminate the fields, or figure out how to ignore them...turn the receiver off.
The fact that you haven't gotten into trouble with how you control the ground current path doesn't mean the problem doesn't exist.
It's a question of mind over matter...if you don't mind, it don't matter.
syn08 said:
If the crosstalk is a result of mutual inductance, you have several choices. Stop the transmitter, stop the receiver, cancel the fields by summation of opposite, or make the structures orthogonal.
Simply paralleling wires doesn't cancel magnetic fields.
They must have a common integrated current centroid. Either twist the daylights outta them, run coax, multiple twisted pairs, or high aspect ratio stripline. There is no other way to eliminate the external magnetic fields of a wire. Conductive shielding at the low frequencies requires just too much thickness for eddy currents to counter the field.
Cheers, John
jneutron said:
Can't speak for the others, but I would love to see some images of the amp you are referring to? Would you post some?
_-_-bear
I'll just make one point: In a split +/- supply the return path is not normally center tap ground (only for the charging currents). The loop goes from the positive side to the negative side. The ground is only a zero reference for the signal.
The simplicity of this statement changes as the power levels goes up, but the concept of shielding the power wires needs to be thought through if viewed in this light.
The simplicity of this statement changes as the power levels goes up, but the concept of shielding the power wires needs to be thought through if viewed in this light.
Oh my...
After reading this thread onwards it seems there is no mention of boxers and debaters trying to smote each other and or how to validate their actions. This is good human progress! I cheer!
So, correct me if I am wrong, the Blow Torch preamp circuit is primarily the same circuit that John developed for the Grateful Dead thingy? And this thread is all about that, (no, I know there is so much more, but I’m trying to find the reduced syrup here). Yes? No?
No folks I’m not kidding, I’ve read this thing up and down I just don’t get it. Is this a long extension of a review from Stereo Review 1989 or is there something going on here that I should be learning and or missing? By the way, I think JC has way more to offer in some other threads here on DIY Audio. I truly love the dude’s way with capacitors!
One more time, I’m not putting nothing or nobody down here but this thread seems to be lacking meat and potatoes. I hate being vague, you all know I’m lying when I write that, but is this some kind of esoterical discussing or are yee all discussing the ins and outs of THE Blow Torch? Shouldn’t a well rounded talk start with some kind of schematic?
Sorry for being a jerk but please help me out, if you can. I walk away now if I’m beating a dead hose.
Happy DIYing!!!!!!!!!!!!
After reading this thread onwards it seems there is no mention of boxers and debaters trying to smote each other and or how to validate their actions. This is good human progress! I cheer!
So, correct me if I am wrong, the Blow Torch preamp circuit is primarily the same circuit that John developed for the Grateful Dead thingy? And this thread is all about that, (no, I know there is so much more, but I’m trying to find the reduced syrup here). Yes? No?
No folks I’m not kidding, I’ve read this thing up and down I just don’t get it. Is this a long extension of a review from Stereo Review 1989 or is there something going on here that I should be learning and or missing? By the way, I think JC has way more to offer in some other threads here on DIY Audio. I truly love the dude’s way with capacitors!
One more time, I’m not putting nothing or nobody down here but this thread seems to be lacking meat and potatoes. I hate being vague, you all know I’m lying when I write that, but is this some kind of esoterical discussing or are yee all discussing the ins and outs of THE Blow Torch? Shouldn’t a well rounded talk start with some kind of schematic?
Sorry for being a jerk but please help me out, if you can. I walk away now if I’m beating a dead hose.
Happy DIYing!!!!!!!!!!!!
No, this is not about the Grateful Dead. There a plenty of schematics posted within this thread for someone to make a virtual 'Blowtorch' However, the specific design is NOT for novice amateurs, as it is just too hard to do right. However, the PRINCIPLES of successful audio design are 'fleshed-out' here far more than usual. It is these 'principles' that I think more important to present than a specific schematic that only a very small number of people could make successfully, in reality.
But will it sound good with my HCA 3500?
Anybody know where I can get some tips on modifying my HCA 3500?
Anybody know where I can get some tips on modifying my HCA 3500?
It is possible, with effort, to make the HCA-3500 almost as good as a JC-1. The actual schematics are almost identical. However, there are dozens of details, that make the difference. This involves: feedback resistors, bypass caps, using high speed diodes instead of normal power diodes, bypassing the Surgistor on the power supply line, transformer polarity, and others that I can't think of at the moment.
Thanks John,
I am a fan. If anything else comes to mind, and you feel inclined, please drop me a line.
I'll let you know what I think about the modified amp.
Matt
I am a fan. If anything else comes to mind, and you feel inclined, please drop me a line.
I'll let you know what I think about the modified amp.
Matt
Some facts.
About preamplifier CTC Blowtorch.
Just in case not everybody knows it all by now 🙂
Dimensions WxHxD: 457.2×88.9×279.4 millimeter
Weight: 17000 gram
About preamplifier CTC Blowtorch.
Just in case not everybody knows it all by now 🙂
Dimensions WxHxD: 457.2×88.9×279.4 millimeter
Weight: 17000 gram
That I will be unable to do.bear said:
I've built two personal amps using the best grounding and e/m layout I could figure out, but didn't have a digi cam to take pics during build. I no longer own the amps, but gave them away to better homes...my basement is too full...
Current work is unfortunately, not allowed for public consumption. IP stuff..not mine, but that of others...
However, that said..there is nothing to prevent the next build with pics, now is there? I've been gathering the parts for a four channel PA setup, here's a partial list of materials..sorry my cam is home today...got the box right here..I can take a pic tomorrow though...
2 plitron #1614 toroids, 225 VA apiece. (I'll rewind the secondaries to get the supply voltage I want plus 12 vdc for the fan.
2 L4780TA chips, dual 60w chips..
1 suitcase, aluminum...to make the thing really portable
2 neutrik 4 pole outs.
4 panny 50 volt 22000 uf caps
1 cpu fan/heatsink assembly.
2 GBU8K bridges.
A roll of 5 mil thick copper sheet, leftover from the home reno. I'm tossed between making the 3 layer supply feed out of the foil with 3 mil sheet insulation....or half inch wide flat copper braids. The foil design is gonna be sexier..I think I'll be able to forgoe bypass caps at the chips cause the foil inductance is gonna be sub nanohenries. But that'll be fun to try...
But I'm not sure this thread is the place for it..perhaps a new one?
Badge said:
I hate to let you down..the schematics for personal use were nothing to write home about. One was a tigersaurus 250 repackaged, the other was a two chip amp using LM 3876T's. It was only the routing and wire layout that was different and new..
The only thing about the tiger that was in any way interesting was it's lack of noise (externally generated) and hum. I always kept the bias turned as low as possible, so the amp was unuseable for critical listening, it was only good for high power PA. (you know, when pigs fly).. At the time, it was used five feet from a 250 kilovolt vandygraf and 10 feet from a toro700 leafblower motor..
MikeBettinger said:
In a split supply feeding a B topology poweramp, there should not be current from rail to rail. When the pos rail is feeding current to the load, the load is returning the current through the ground. Then neg current is through the other rail but still returns through the ground.
Both rails have to be very intimate with the ground return. I don't ground the load terminal at the binding post or neutrik, but bring that current back to star..
An H bridge works as you say, but I'm not sophisticated enough to deal with H's yet.
Cheers, John
ps.. I purchased 2 mp3 usb sticks as music source, so I''ll probably have to also put 5 volts or 1.5 volts in..and I'm seriously thinking of building the mike pre/mixer from scratch, as I am scared of relying on the Behringer UB-502 or the UB-802. They were too inexpensive to make me wanna rely on them..gut feeling, no experience with failures to date, three years now..
jneutron said:
Hi John,
I was discussing preamp levels, you'll note my comment about things changing as the power levels went up. Actually as I think back on it I should have picked up on your comments being amp based.
In a preamp the majority of the currents are bias related and flow from neg to pos, the signal currents are negligable.
In my amps I do as you mention as far as the speaker return, back to the power supply reference. There are no grounds used in the driver/output or voltage amp stages so there would be no return currents to follow the supply connections. There is a ground for the input and the +/- regulators for the servo supply; these returns mirror the supply feed as you suggest.
I believe we are saying similar things only with different experience and points of view.
Regards, Mike.
As far as the HCA-3500 goes, silver fuses OR circuit breakers to replace the fuses would help also.
Thanks John, will do.
I picked up a HCA2200ii from Audiogon, delivered today. I have my fingers crossed that is a good one.
Matt
I picked up a HCA2200ii from Audiogon, delivered today. I have my fingers crossed that is a good one.
Matt
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