2N1711 is available from Element 14 - brand Multicompro and Digikey - brand Central Semiconductor. It is designed primarily for amplifier and switching applications with high breakdown voltage, low leakage current low capacity and beta useful over an extremely wide range of current. It has low noise and is suitable for oscillator applications where device tolerances are important.
Cordell .models he lists 2SC3503 now KSC3503 and BD139 for TR forward transit time and TF reverse transit time these have the same results 10 nano seconds and 585 pico seconds respectively.
Comparable figures for 2N1711 are 815.2 pico seconds and 499.1 pico seconds.
Bf Beta factor respective figures are 170 KSC3503, 260 BD139, and 213 for 2N1711. The last pair have similar early voltage figures VAF of 100 while KSA3503 figure is 769 which is excellent. I have simulated with BD139 and 2N1711 but not for KSC3503
I have toyed with the idea of building a modified version of the JLH1996 with an LTP input stage using MJL3281 outputs for various power levels and with increased closed loop gain where a volume control and input switch where the input could be a direct feed. I have simulated the circuit, which gives cbetter THD figures but I am happy with the design as built in accordance with the 1996 Electronics World article.
I have built and repaired a fair number of amplifiers since 1976 when built the 1969 version, and have owned and still own four commercial designs -ones having higher power output capability. I am happy with all of these however there is something about the sound of JLH design that I find most attractive despite the technical details.
JLH and Nelson Pass have commented simple designs often sound more musical.
This is my JLH69.
It consists of bc559, ksc3503, mjl 3281 transistors.
supply voltage 24vAC 32vDC
dual mono
Bias 1 Amper
Av=23db
I listen to music by heating my study room in cold winter months
It consists of bc559, ksc3503, mjl 3281 transistors.
supply voltage 24vAC 32vDC
dual mono
Bias 1 Amper
Av=23db
I listen to music by heating my study room in cold winter months
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2N1711 is a TO-39 case. I would not use: very poorly defined "current". Does sound flat, grey, noisy - compared with a good or very good TO-126 transe.
Is it useful to combine psu's?
If the preamp is a common gnd and the power amp is a common gnd, won't a ground loop occur?
Later take care of any ground loops that may occur.
Basically, I would also lay only one ground connection, despite two, channel-separated, RCA connections (I usually use the right channel for this.). Some reasons: smaller cross sections, no loops.
I foretell:
1. connect both psus together.
2. use one rectifier for both channels.
3. use one secondary winding only for all.
4. do not use cable lugs.
I wouldn't say a metal case has anything to do with defining a transistor's "current" or perhaps you mean noise susceptibility? A TO126 transistor case will admit much the same amount of radiated noise since the collector is bonded to its flat backplate (or heat spreader) and significant connecting lead area. However, the collector is a low impedance circuit node (i.e. insensitive to radiated noise) so I don't think there will be any real difference in using a similar chip in an old TO39 style case.
In any case
JLH seemed happy to retain the TO39 types 2N697 or 2N1613, long after cheaper TO126 styles were already available.
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I should add that it's likely your 2N1711 and many other semis that are obsolete but desirable to hobbyists, is actually a fake. Fakes can be produced with the obsolete, original tooling and marking equipment too - such that they appear to be identical. Only authentic factory documentation would prove them genuine though.
Also, in the above post #8568, I referred to 2N697 as having a TO39 case. Apparently this is wrong, as datasheets show the similar, older T05 style.
Also, in the above post #8568, I referred to 2N697 as having a TO39 case. Apparently this is wrong, as datasheets show the similar, older T05 style.
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2N1711 is specified for low noise which you can look up. In simulations of the
ST list them as obsolete however as mentioned in my post 8561 these are available from other makers Multicompro and Central Semiconductor.
It is worth mentioning that in simulations there is no difference in slew rate or THD results between 2N1711 and KSA3503 in my test circuit however the former has higher stability margins of the two gain 25dB versus 21dB for example. Both results are satisfactory as phase starts to alter a decade below the -3 dB gain point 0.707 of unity gain where the slope is 6dB per octave - that is 20 dB per decade so you are well covered.
At 1Watt into 8R THD is 0.006% at 20kHz. This does increase to 0.05% at 15W but that is academic as the amplifier would clip on the lower bass and mid frequencies. The FFT is monotonic. There is a noise specification for 2N1711 there is none for KSA3503.
cumbb has done a good job with his build however this could be improved avoiding radiated fields due to switching action of the bridge rectifier charging the supply capacitors.
All that is required is to twist the leads tightly so these fields effectively cancel one another. Also it would be worthwhile if there is no copper flux band around the transformer windings to take this to a transformer winding company and have one fitted. I built the 1969 JLH in a steel metal cage designed for a valve amplifier. the field around the transformer was sufficient to cause the cover to vibrate and generate a fair amount of mechanical noise.
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The tube amplifier is warmer and has a magical light 🙂
Can I add vibration isolation pad (mat) under the transformer?
Current. Flow. In a medium. Visualized. Large;-)
Process.
Undefined.
Including pre-stream (seeker) and post-stream (straggler).
Every single signal in a new definition. Constant redefinition. Constant signal-change.
Do we hear this non-definition, constant redefinition, signal-change?
Could we define current - a little bit exacter -, practically?
Process.
Undefined.
Including pre-stream (seeker) and post-stream (straggler).
Every single signal in a new definition. Constant redefinition. Constant signal-change.
Do we hear this non-definition, constant redefinition, signal-change?
Could we define current - a little bit exacter -, practically?
Attachments
Quote, OldDIY: Can I add vibration isolation pad (mat) under the transformer?
An isolation pad would have to support the mass of the transformer + any necessary mounting force. That's not simple to do because most synthetic foam materials are too soft, compressing down to nothing after some period of time at typical transformer operating temperatures. A piece of say, 8-12 mm solid but relatively soft neoprene rubber sheet laminated with rigid insulation board, could be effective though. Closed-cell neoprene foam sheeting is available too but I doubt its longevity. Here in Oz at least, there are some heavy machinery installers and automotive suspension specialists who use and sell suitable thick neoprene and other sheet rubbers, in roll form but I have no idea of your local sources or minimum purchase quantities. You need only a little of the stuff and that makes it hard to find a seller.
Re: 2N1711
We can certainly buy genuine parts, if and when they are actually in stock at 2nd sources like Central Semi and their resellers. Most of us though, will actually be sourcing all components together in kits and small quantity parts packs from Chinese platform sellers. That's what actually happens among local friends in my area at least. Some of the semis may well be genuine product but most won't, judging by incredibly low prices which suggest that you can buy a complete stereo PCB kit with all specified components, including postage, for less than the total supply cost of just the 2 genuine transistors, likely direct from the US source.
An isolation pad would have to support the mass of the transformer + any necessary mounting force. That's not simple to do because most synthetic foam materials are too soft, compressing down to nothing after some period of time at typical transformer operating temperatures. A piece of say, 8-12 mm solid but relatively soft neoprene rubber sheet laminated with rigid insulation board, could be effective though. Closed-cell neoprene foam sheeting is available too but I doubt its longevity. Here in Oz at least, there are some heavy machinery installers and automotive suspension specialists who use and sell suitable thick neoprene and other sheet rubbers, in roll form but I have no idea of your local sources or minimum purchase quantities. You need only a little of the stuff and that makes it hard to find a seller.
Re: 2N1711
We can certainly buy genuine parts, if and when they are actually in stock at 2nd sources like Central Semi and their resellers. Most of us though, will actually be sourcing all components together in kits and small quantity parts packs from Chinese platform sellers. That's what actually happens among local friends in my area at least. Some of the semis may well be genuine product but most won't, judging by incredibly low prices which suggest that you can buy a complete stereo PCB kit with all specified components, including postage, for less than the total supply cost of just the 2 genuine transistors, likely direct from the US source.
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Similarly, I once used a gel insole insert for shoes. Worked great. Some stores carry cheap generic versions.
He sometimes thnks in pictures, leaving it up to the reader to associate it with relevance.
probably better mounted on a pcb with rubber grommets to the chasis
https://sklep.toroidy.pl/en_US/p/Mounting-panel-for-Chassis-DT1-and-DT2/301
https://www.aliexpress.com/item/32924247409.html?spm=a2g0o.cart.0.0.14f638darvswTj&mp=1
https://sklep.toroidy.pl/en_US/p/Mounting-panel-for-Chassis-DT1-and-DT2/301
https://www.aliexpress.com/item/32924247409.html?spm=a2g0o.cart.0.0.14f638darvswTj&mp=1