2SJ50/2SK135
TO3 were about the best for class A but the mounting method, the drilling, possible faults were terrible. Not many liked the intensive way of using these as precise mechanical work is doo-doo to many.
However trusting the casing to make good contact with the M3 bolts and the contact of the M3 nut via a washer to the PCB was not advisable. Adding solder lugs and wire was a definitive solution but again extra work.
TO3 were about the best for class A but the mounting method, the drilling, possible faults were terrible. Not many liked the intensive way of using these as precise mechanical work is doo-doo to many.
However trusting the casing to make good contact with the M3 bolts and the contact of the M3 nut via a washer to the PCB was not advisable. Adding solder lugs and wire was a definitive solution but again extra work.
Last edited:
The entire organism hears: is set into swinging; a swinging and electro system. And (hifi) sound images are stored in the entire organism. We carry some of them around with us for decades. HiFI is not just the reproduction of individual tones but of complex sound images that are a connection between colors, shapes, rhythms, intervals and more.
True, not only the eardrum, but the entire body vibrates.
It doesn't apply to everyone-everyone, obviously. 😉
The development of the housing shapes is not based on the knowledge of current and signal as a process. I have a few of these Htachis lying. They are simply unsuitable for audio. They are an audio untested, collectively handed down myth. But you could rework them, but the result would not justify the effort. I would use them for disco systems and open air.
One of the best amplifiers I had in the past had these. Used several tens of them in many high bias amplifiers, never had one failing except a kind of “wearing out” after years of class A use. Trouble free, reliable and good sounding so wonderful parts. Therefor liked by many. The amplifiers I built with them still work today and are still found competitive.
Probably some tiny technical theoretical inconvenience not too relevant in real use can be found. As with many parts as nothing is ideal.
No offense but your hard statements that these are unsuitable for audio and TO3 is worst sounding are both clearly false as proven by many known good audio devices that have either of them. Not many will say a JLH 1969 to be bad sounding 🙂 Quite unscientific too. Probably high brow “water = poison” like attention drawing provocation. Have a nice day!
Probably some tiny technical theoretical inconvenience not too relevant in real use can be found. As with many parts as nothing is ideal.
No offense but your hard statements that these are unsuitable for audio and TO3 is worst sounding are both clearly false as proven by many known good audio devices that have either of them. Not many will say a JLH 1969 to be bad sounding 🙂 Quite unscientific too. Probably high brow “water = poison” like attention drawing provocation. Have a nice day!
Last edited:
Generally I could not care less how amplifiers measure and own some that do not measure very well but which sound very good to me.Having said that though whenever I have heard or used anything Accuphase I have been impressed by their sound.And they seem to always measure very well.But that does not mean they sound good because they measure well.More likely because they have vast experience ,are fanatical about all aspects of quality and obviously employ very good designers.
Which amplifier do you name specifically?
Anyone can convert his TO-3 JLH in no time at all and test my statement, claim. Most TO-247 types will sound better.
Can you post a circuit? My small brain doesn't unnerstan "half-wave asymmetrical complementary transistors pp, 2-stage. " You can leave out the choice of transistors and values as I think we now understand your choice.
And what did you hear when you removed the bootstrap capacitor on your JLH 10W Class A? If you didn't actually do the test yourself, that's OK too. But we need to know.
Tom, in general I (and my DBLTs) agree with you. ALL of the Golden Pinnae we tested that sounded 'different' exhibited nasty overload behaviour, instability with real loads, high xover at times bla bla .. all dependent on the signal & thermal history .... and marked down compared to boring low THD, unconditionally stable amps.
The exception was the little JLH 10W Class A Gotta point out only the very best ears in my very select DBLT panel could pick the difference if the amp wasn't overloaded. Slight but consistent preference even though THD at full power was only 0.1% .. not 1ppzillion
There's a couple of products we made that had exceptional performance in DBLTs. I wish I knew what it was that made them so good as we had other designs with the same ju ju with good DBLT performance but not exceptional. Of course I could and did generate loadsa solid BS for marketing. (R&D BS is always solid while marketing BS is liquid) But in the cases I'm thinking of, I really don't know.
Last edited:
Again a non true statement/claim. Anyone that really builds stuff will not state a conversion from TO3 to TO247 can be done in no time as it just is the opposite. From L-bracket to a flat surface heatsink, redrillling and deburring etc. Some similar statements: "vegan = healthy", "electrical = green".
Off to breaking down a tile wall. Ciao!
In other words you will hear the bs capacitor in that JHL amp, it will dominate the sound signature of it.
I thought about thd and finally it is very useful to build and design the amplifier as a guide, shows that parts function properly, that each stage function adequately, voltages are right, and it is going to be reliable. Getting an amp out of production with one channel with high THD is a sign of problem, defective part, of bad solder.
If two design are available in the market I will choose the one which performs better in THD, I will think the circuit is better.
I thought about thd and finally it is very useful to build and design the amplifier as a guide, shows that parts function properly, that each stage function adequately, voltages are right, and it is going to be reliable. Getting an amp out of production with one channel with high THD is a sign of problem, defective part, of bad solder.
If two design are available in the market I will choose the one which performs better in THD, I will think the circuit is better.
"half-wave asymmetrical complementary transistors pp, 2-stage": an example see below
Why I mention complementary transistors: these are clearly different in sound. So we get two half-waves that sound perceptibly different to the ear. In general, a break can be heard, like a Spanish wall in the illustration. In addition, color and verve are lost. And more.
Half-wave unsymmetric: the two half-waves amps run per different number of components, or even differently in operation. This is also clearly audible. PN transitions, such as these two diodes as a bias voltage, draw a veil into the picture, it also appears more technical, more artificial, compared to resistors, for example.
BS cap on JLH: diy audio
Attachments
An amplifier should amplify. It should not change the information it receives, it should only amplify it. Low distortion is then mandatory. I will not buy or build an amplifier that purposely changes the information it receives.
But this is just my opinion of course. It really, really, really doesn't matter what I or anybody says as long as you are happy.
I am very happy with my amplifier. It has many transistors, capacitors and other unholy components.
If there are people that don't like an amplifier because it has transistors with a certain package, then I hope they don't buy or build an amplifier with those transistors. But they shouldn't tell other people what to like as if their preference is the only true way to go.
My answer to the original question is: It's up to you and your expectations.
But this is just my opinion of course. It really, really, really doesn't matter what I or anybody says as long as you are happy.
I am very happy with my amplifier. It has many transistors, capacitors and other unholy components.
If there are people that don't like an amplifier because it has transistors with a certain package, then I hope they don't buy or build an amplifier with those transistors. But they shouldn't tell other people what to like as if their preference is the only true way to go.
My answer to the original question is: It's up to you and your expectations.
We do actually have a box where we can connect equipment and determine if it will be well-liked or preferred in a blind test. That's called an audio analyzer. Gear that measures better tends to be preferred in blind trials. But science is often thrown out the window in audio.
Also, a double-blind listening trial is not likely to tell you whether a particular piece of equipment will suit your tastes. Maybe you like a little bass boost or maybe you like the sense of a larger sound stage that can come with higher low-order harmonic distortion on simple music. You can like those things and still be a good person. 🙂 I'm not here to judge. With measurements you can easily see whether a piece of gear will be suitable to your taste or whether you should just move on. That has value too.
I bristle at statements like "measurements are useless". To me, that shows lack of understanding of the measurements and lack of experience with what it takes to design a circuit that measures well on a range of parameters.
But as I also pointed out, I also take issue with the almost militant application of (pseudo-)science and measurements seen on ASR. There's no science being conducted there. I dare you to criticize Amir on anything. I've tried. It didn't go well. Science involves peer review and continuous improvements. That's hard to do when the "scientist" always needs to be the smartest person in the room.
The main reason I put little value in subjective reviews is that there are too many sources of error and the terminology used in subjective reviews is ambiguous at best.
That said, there are things other than measurements that also matter. I have a preference for well-engineered products. So when I was looking for a DAC my choice was the RME ADI 2 FS. That's a solid product. But I could probably have bought three Topping DACs for the same price. That's fine by me. I'm happy to support a small German company. I also have confidence that the DAC won't blow up when I turn it on or touch the volume control. That adds value too.
Tom
I agree, there is no doubt about this.
Yes, it's the quality I appreciate most in a conversation, on a forum or anywhere else.
How?
I totally agree and it would bother me too because it would be nonsense, but it seems like no one in this thread said it and I guess no one in the entire forum has ever said it.
I did a search for the term "useless" and it seem to me that someone who used it was referring not to the measurements, but to the "useless" threads that bother him so much and that instead of avoiding reading them he posts that those thread are so useless and bother him so much. 🙄
I've been arguing for a few days that it doesn't really matter that much that any review runs the risk of not being entirely reliable, since it is an expected risk.
And it surely is an expected risk, since presumably anyone who imagines buying a device after reading a "positive" review, that is, that they liked it, will try it in their system before buying it.
Unless you think that buyers of audio equipment are naive people who are easily influenced and who simply need to read a good review to buy a device.
There's already someone in this thread who suggested something similar, do you think so too?
I believe and hope not.
We never know.
The abnormal factor, the human factor or a risk factor will always exist regardless of the nationality of the manufacturer, in my humble opinion.
I agree, however, that some nations have managed/demonstrated to be considered more reliable than others.
Unless they have their devices produced in the very nations you mentioned earlier, of course...
Sorry. I thought it was obvious. If you prefer equipment that boosts the bass, look for a bass boost (or rising THD at LF) in the measurements. If you prefer equipment that has higher low-order distortion look for equipment that shows higher low-order distortion in the FFT. You can correlate measurements with your perception to figure out what you like.
What I meant by sources of error is all the perceptive errors and biases that are the result of input from our other senses. A lot of sighted reviews are heavily influenced by how the equipment looks, feels, how heavy it is, how expensive it is, etc. Olive & Toole have tested this scientifically. You then add that many, if not most, of the established reviewers provide a review in exchange for getting the equipment on "permanent loan". I.e., they get to keep the gear in exchange for a review. Do you think this might influence their review? They also have concerns such as ad spend by equipment manufacturers to take into account.
Maybe. There are fewer and fewer high-end hifi stores these days. Not all will allow you to take the equipment home to try it. I suspect a lot of gear is bought because of a positive review and either kept or returned to the seller.
I don't think buyers of audio equipment are any more or less naive than the rest of the population. I do believe that buyers of audio gear are humans. And humans are not rational critters. For an entertaining and light-hearted review of the science on that topic, I recommend Dan Arieli's Predictably Irrational. It's a good review of behavioural economics.
Tom
Thanks for this cumbb. I have actually built & used such a device some 55 yrs ago but not done DBLTs. However, I can report that a Boostrap cap improves clarity & definition greatly. Probably cos I did not use TO-3 devices 😊
Are you saying you didn't actually carry out the said listening test on removing the Bootstrap cap???!!BS cap on JLH: diy audio
Haha, I really love the sound of the Maplin amplifiers, based on a Hitachi datasheet audio design using these MOSFETs!!
For audio they are great because they have a positive temperature coefficient, and they are fast and can move a lot of current.
I actually listen to a Class A single ended tube with a very clear, open, effortless sound, (with the OPT outside of the feedback loop), and to the Maplin Hitachi MOSFET designs in other rooms, and the MOSFETs don't sound that much different from the tube amp!
This is with both classical and rock, on both types of amp.
So my experience of these MOSFETs, treated well, can really shine for audio 🙂
The Maplin circuit I mention above, runs a 100mA bias, so much of the low level sound is actually class A.
In the simulation, this region is cleaner (FFT graphs) than the AB region.
Currently I have 2 Maplin modules with the transistors bolted to a massive pair of Sony heatsinks, far bigger than the original Maplin designs. Currently 100mA, at about 100V is 10W per amplifier, probably they could dissipate about 50W with a super quiet fan at the bottom, just idling, which would be a 0.5A idle, I suppose 0.5A into 8 Ohm (when it comes out of Class A?) is I^2.R = 0.25 x 8 = 2W of class A>
Note: my evening maths might be way off😀
But 2W is probably quite a usable amount - most of the time everyone is in the 1st or 2nd Watt, so maybe that's an interesting thing to try...!
This would mean you like the use of an output coupling capacitor > would it not?
If so, what type of capacitor and what value is your preference?
Last edited:
- Status
- Not open for further replies.