Yea, the package sucks for DIY too. I managed to get one down and found 25mV of offset so the match is so-so.
With the pinchoff voltage thus and high Idss they might be o.k. for cascoding---except in that package the max dissipation is pretty small.
I thought I mentioned thee before, but since we are on the topic :
CPH6904 (6 pin)
www.onsemi.com/pub/Collateral/ENA1966-D.PDF
MCH5908 (5 pin)
www.onsemi.com/pub/Collateral/ENA1218-D.PDF
Patrick
CPH6904 (6 pin)
www.onsemi.com/pub/Collateral/ENA1966-D.PDF
MCH5908 (5 pin)
www.onsemi.com/pub/Collateral/ENA1218-D.PDF
Patrick
Blues -- get: The Breeze.
An appreciation of J.J.Cale.
Travel .... never go with a group... even if you dont know how or where you are going exactly.... is my motto. One time, recently, I got excited when I found a way to get to XIAN, China. There wasnt a way from Bangkok.... so I went up north to Chang Mai and there was a plane to XIAN from there...... I as so excited, I bought tickets as soon as I landed in C.Mai and took off again. Only one problem, I did not think about...... dropping into the middle of China without a Visa can get you a long term in a prison in some remote, unknown place. But it worked out great and I got a private tour of the region by the daughter of Xian's chief of police. She showed places no one outside China had seen and was an expert in history. One of the best times I ever had - which could not be had without just 'going for it' on your own.
THx-RNMarsh
An appreciation of J.J.Cale.
Travel .... never go with a group... even if you dont know how or where you are going exactly.... is my motto. One time, recently, I got excited when I found a way to get to XIAN, China. There wasnt a way from Bangkok.... so I went up north to Chang Mai and there was a plane to XIAN from there...... I as so excited, I bought tickets as soon as I landed in C.Mai and took off again. Only one problem, I did not think about...... dropping into the middle of China without a Visa can get you a long term in a prison in some remote, unknown place. But it worked out great and I got a private tour of the region by the daughter of Xian's chief of police. She showed places no one outside China had seen and was an expert in history. One of the best times I ever had - which could not be had without just 'going for it' on your own.
THx-RNMarsh
Last edited:
6nV/sqrt Hz typ @ 100Hz.
It consists of 2 chips that are isolated and sit on their gate pads,
as should be expected. I just cut one open.
Why can't they do that with selected BF862 ???
I also just found a piece of MMBF5460LT1G tape which is one of the few surviving
p-channels. But 60 to 115 nV/sqrtHz. That hurts.
THE GOOD NEWS:
I just got my copy of Hill's Art Of Electronics release III
That cold & rainy Easter weekend is saved!
Gerhard
Last edited:
He obviously apply this principle to his musical life: A different city with different musicians for each tune. And he visibly get bored pretty fast by their presence: each tune is very short ;-)
John, when you were designing Parasound Halo JC 1, why didn`t you start as making it as linear as you could, in open loop (without global feedback loop), and then raise the gain and close the feedback loop, I get the feeling that you relied on the fb loop from the start or am I wrong? BTW you could get that distortion figures for THX or whatever with much less GNFB and better design...
Why don`t you experiment with topologies a little bit, your last amp is same as your first, just with little bit upgraded schematic and new parts.
Slightly OT (if that is possible here):
I need to get a stripper for my rework kynar wirewrap wire. Wire outside diameter with insulation is 0.4mm, the wire itself is 0.2mm.
Do I get a 0.4mm stripper or a 0.2mm stripper? I looked at a bunch of datasheets but they do not tell what the specs refer to.
Thanks, Jan
I need to get a stripper for my rework kynar wirewrap wire. Wire outside diameter with insulation is 0.4mm, the wire itself is 0.2mm.
Do I get a 0.4mm stripper or a 0.2mm stripper? I looked at a bunch of datasheets but they do not tell what the specs refer to.
Thanks, Jan
Bogdan, thanks for your input. I do try to make a specific design as linear as possible, always. However, I don't 'cut and try' and 10 years ago, I did not bother with Spice simulation, either.
I use a design topology that I first developed over 40 years ago, and just make it bigger and better.
Parasound had already made a number of amp models following this basic topology, with good success, most of the time. However, we found that two other areas of design had to be seriously included to make a really optimum design. First, was upgrades in parts quality, including caps, wire, and connectors, diodes, etc.
At the same time, we wanted an optimum layout from my former Vendetta and then CTC business partner, to do the circuit layout. We had to put a lot of energy into just getting what we got done, and I deliberately stuck with an 'improved' version of the HCA-3500, to see what these changes in layout and parts quality would give us.
I have done other amps that would cost even more than the JC-1, if produced today, but Parasound was not set up to pay me enough to develop them, although I had developed 3 working models in the past for other manufacturers, so we stuck with the standard topology.
I use a design topology that I first developed over 40 years ago, and just make it bigger and better.
Parasound had already made a number of amp models following this basic topology, with good success, most of the time. However, we found that two other areas of design had to be seriously included to make a really optimum design. First, was upgrades in parts quality, including caps, wire, and connectors, diodes, etc.
At the same time, we wanted an optimum layout from my former Vendetta and then CTC business partner, to do the circuit layout. We had to put a lot of energy into just getting what we got done, and I deliberately stuck with an 'improved' version of the HCA-3500, to see what these changes in layout and parts quality would give us.
I have done other amps that would cost even more than the JC-1, if produced today, but Parasound was not set up to pay me enough to develop them, although I had developed 3 working models in the past for other manufacturers, so we stuck with the standard topology.
I have used one of these for many years:
WIRE STRIPPER AND CUTTER ST-100 SERIES OK INDUSTRIES / RS 543-771 | eBay
WIRE STRIPPER AND CUTTER ST-100 SERIES OK INDUSTRIES / RS 543-771 | eBay
I have an adjustable one (no longer listed) similar to Knipex, works great on small wires but pricey (you have to pay for German engineering).
So many JC-2 clones .....
I had lots of iterations of this most copied circuit. I suppose the fact so
many Chinese kit makers copy is the ultimate "flattery".
I could not get the basic JC-2 below .01% THD20. The Jfets and it's utter
simplicity might be the reason for such a "following".
Going from the 200W amps to a class A line-stages was fun. I could run
everything hotter , use low Vceo/low noise semi's .... and have a class A
output.
Symmetric is the way to go ... the leach/hawksford circuit did 2ppm-20K !
(below)
Sub -PPM at 1k - a nice 5X "wire with gain".
A Jfet cascode did the same (almost). Jfet models are crap - still <5ppm.
The hawksford was the real change that made the "bottom drop out"- THD
wise.
I'm going to build it ! (any ideas - never built line stages , just big amps)
OS
I had lots of iterations of this most copied circuit. I suppose the fact so
many Chinese kit makers copy is the ultimate "flattery".
I could not get the basic JC-2 below .01% THD20. The Jfets and it's utter
simplicity might be the reason for such a "following".
Going from the 200W amps to a class A line-stages was fun. I could run
everything hotter , use low Vceo/low noise semi's .... and have a class A
output.
Symmetric is the way to go ... the leach/hawksford circuit did 2ppm-20K !
(below)
Sub -PPM at 1k - a nice 5X "wire with gain".
A Jfet cascode did the same (almost). Jfet models are crap - still <5ppm.
The hawksford was the real change that made the "bottom drop out"- THD
wise.
I'm going to build it ! (any ideas - never built line stages , just big amps)
OS
Attachments
When carried on too far, subjectivism can produce some funny effects. For example, a lot of local DIYers have come to believe that current feedback is the not just THE thing, if it's not current NFB, then it can't sound good. They forgot real fast that until a few months ago, they were swearing on their voltage feedback gear and hand products.
Ok, so how does the sim report with variable source impedance...ie, connected to the wiper of a volume pot, say 5k, 10k, 20k, 50k at differing pot positions ?.
How 'bad' does the 0.01% JC-2 actually sound in practice ?.
Dan.
Some thoughts from following along your journey in topologies ---- one thing seems never got resolved was the Slew Rate and what differences it made to subjective results.... using very low thd (<-100dB) and same topology. High SR vs minimum (.5v/v - 1v/v).
jFET models are crap and so are many compliment jFEt parts available. A real problem for symmetrical topologies..... causing circuits to get more complicated for low distortion.
Never- the-less, selection of jFETs in the simple circuits is absolutely a requirement for lowest distortion in practice. Relatively simple circuits have produced -120dB levels (measured) with selection and trim. This isnt practical for mass production but it is for DIY or limited production HiEnd construction products.
Since, you, myself and others have shown you can get 'The Numbers' in many forms of circuitry, the circuitry/topology with the fewest parts while maintaining highest performance levels, wins IMO.
THx-RNMarsh
Last edited:
- Status
- Not open for further replies.