Dunno about that. Sure, the design is old, but for an A/AB audio amplifier, you won't need a fT above 0.8MHz. The newer OnSemi 2N3055Gs are great BJTs for Class A operation, have a fT of 2.5MHz, and are RoHS compliant.
Attachments
I just looked up MJ480 as I believe JLH used. Very reasonable specs. Gain 30 to 200 and fT 4MHz. Slightly better than a typical 2N3055. From memory TIP3055 is better. One person here said TIP3055 is not a true 2N3055. Some Indian 3055 I used might be another T0247 type in a T03 can. They seemed rather good.
As you know, I have and have had a very large number of transistor or tube amplifiers.
I still have a good thirty at home.
however, I cannot detach myself from my jlh.
they are not perfect but few other amplifiers sound as good at low volume.
I have not yet entered the "matrix", my knowledge is therefore limited but I would like someone to explain to me or try to explain to me why it works so well at low volume and is able to grow 30 or 38cm with such ease.
however, please believe me when I say that I got a lot of amps, I'm not kidding.
I still have a good thirty at home.
however, I cannot detach myself from my jlh.
they are not perfect but few other amplifiers sound as good at low volume.
I have not yet entered the "matrix", my knowledge is therefore limited but I would like someone to explain to me or try to explain to me why it works so well at low volume and is able to grow 30 or 38cm with such ease.
however, please believe me when I say that I got a lot of amps, I'm not kidding.
I built a very simple two valve single ended amplifier with no global feedback and very little additional local feedback. I take a triode to be an internal feedback device. Power was 6 watts. THD 1 % which reduced to 0.2% at 1 watt. The input sensetivity 600 mV. It started at 5% THD which took months to reduce. It had a beautiful ability to show the way the microphones do their work. Much more space around voices and instruments.
My best guess is simplicity with reasonably good distortion is what works.
My best guess is simplicity with reasonably good distortion is what works.
afterwards, I think it's like a simple dish with few ingredients.
the simpler it is, the more important the processing and the ingredients.
for my ears, the simplest jlh (without bias potentiometer) is the one that sounds best but the power supply represents 90% of the volume and the final result.
the simpler it is, the more important the processing and the ingredients.
for my ears, the simplest jlh (without bias potentiometer) is the one that sounds best but the power supply represents 90% of the volume and the final result.
You probably are not far from me here in Dorset. Friends in Belgium, France and Luxembourg inform us of life. Hi fi is a beautiful diversion.
I shall make a RH34 amplifier one day. I did try one. I couldn't match the specification given by Alex Kitic. My valve design used positive feedback as does the JLH bootstrap.
I shall make a RH34 amplifier one day. I did try one. I couldn't match the specification given by Alex Kitic. My valve design used positive feedback as does the JLH bootstrap.
a diagram and a nomenclature of your amp is available?
I have a lot of tubes and opt available and above all, thanks to the lockdown, time without constraints
I have a lot of tubes and opt available and above all, thanks to the lockdown, time without constraints
you are still free in GB?
beyond the sanitary side, I think this lockdown is a very good thing for the mind!
many people will reconnect with themselves and understand how beautiful and precious life is but also that certain things are superfluous or even unnecessary
beyond the sanitary side, I think this lockdown is a very good thing for the mind!
many people will reconnect with themselves and understand how beautiful and precious life is but also that certain things are superfluous or even unnecessary
Last edited:
Well said 100%. We are in effective lockdown. Dorset is very like France. We are able if sensible move around. I suspect we are one week away from total lockdown. My friend Janine is a gifted musician. Ex BBC sound engineer. She has been very unwell. She is a school teacher. She is very critical of colleges who do not come to work. The UK prefers for now to teach children. This is mathatically not stupid except for the teachers. Janine told me she has 92 tape recorders. She has a Krell and Leak valve amplifiers. We like the Leak best of all.
I sincerely hope that our English friends will get by with the least possible death.
I deplore brexit but it's another debate ...
I like leaks, I have a clone of a TL25 + built from A to Z by a neighbor in Brittany, full home and hand made including the power supply transformer and the output transformers, it works admirably well.
I also have another of its 2E22-based amps, it is remarkable !!!
I sincerely hope that your friend Janine will recover and regain good health without any after-effects.
my new girlfriend is Irish, pianist and singer, I'm starting to introduce her to our "electronic universe" because she has such a great ear !!
I deplore brexit but it's another debate ...
I like leaks, I have a clone of a TL25 + built from A to Z by a neighbor in Brittany, full home and hand made including the power supply transformer and the output transformers, it works admirably well.
I also have another of its 2E22-based amps, it is remarkable !!!
I sincerely hope that your friend Janine will recover and regain good health without any after-effects.
my new girlfriend is Irish, pianist and singer, I'm starting to introduce her to our "electronic universe" because she has such a great ear !!
The checkout guy at Lidl had a mask. I needed to ask. He has immunity problems. I said he should go home. I also said he is now famous.
I hope a simpler EU will exist soon. It must. I am a Christian of sorts so hope for these things. I hope that isn't political or religious as it's not my intention.
JlH. The simplicity is both it's advantage and problem. Transistor gain needs to be high and oscillation avoided.. Citroen 2CV was in concept similar. If understood it was remarkable. A very famous formula one guy considered it remarkable.
I hope a simpler EU will exist soon. It must. I am a Christian of sorts so hope for these things. I hope that isn't political or religious as it's not my intention.
JlH. The simplicity is both it's advantage and problem. Transistor gain needs to be high and oscillation avoided.. Citroen 2CV was in concept similar. If understood it was remarkable. A very famous formula one guy considered it remarkable.
a 2cv is something which one can neither add nor remove something without modifying it profoundly or unbalancing it.
the simple fact of wanting to add a car radio to a 2cv poses a problem.
it is a precarious balance but which works perfectly
the simple fact of wanting to add a car radio to a 2cv poses a problem.
it is a precarious balance but which works perfectly
It is a wonderful engine based on BMW motorcycle of 1933. The suspension is resistive. I am an accidental mechanical engineer. My family have history in this including Westlake. Jaguar engines were Harry Weslakes design. My uncles friend.
Electronics my passion. I have taught mechanical engineering to BSc students. I have no qualifications. I oversaw projects. One guy who was of concern did very well. He did a motor vibration analysis for me.
Electronics my passion. I have taught mechanical engineering to BSc students. I have no qualifications. I oversaw projects. One guy who was of concern did very well. He did a motor vibration analysis for me.
same route.
I come from mechanics, specializing in the restoration of collector vehicles.
from steam, through heavy oil, ethanol, to production in the 1970s.
I worked on automobiles, motorcycles, trains, stationary engines, boats, two or three pre-war planes and so on.
I did some stato and turbo propulsion, but there I reached my limits.
today I'm a refrigeration technician
I come from mechanics, specializing in the restoration of collector vehicles.
from steam, through heavy oil, ethanol, to production in the 1970s.
I worked on automobiles, motorcycles, trains, stationary engines, boats, two or three pre-war planes and so on.
I did some stato and turbo propulsion, but there I reached my limits.
today I'm a refrigeration technician
I was an amateur. I always remember that amateur means he or she who loves. It's more or less a French word from the Latin. Some would not know that. In English amateur sometimes means less good. Not true.
We have identical tastes! I risked today showing the real me. Glad I did. A lady said today we must be gentle with each other. I didn't say anything much to hear that.
.... and who said that chivalry is dead. Maybe common courtesy is on the way back amid all this.
Regards
Mike