JLH 10 Watt class A amplifier

I only tried one channel. I will make biamping design. I will change output capacitor with film caps with capacity of around 150-180uF for my 4 ohm fullranges. I will use another amp for my 13 inch sb acoustics. I am just curious if using symmetrical suplly jlh sounds better for bass amp because of lack of output capacitor.
 
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You need a huge amount of capacitance for sub-bass and it should be a low ESR, long life type. These are usually large and very expensive so it is really a question of the the economy of the design. It will likely be cheaper and possibly better sounding to simply build direct coupled amplifiers and lose the caps. If you want to use a common PSU for all amplifiers, it would make sense to have them all direct coupled by changing to say, the JLH '96 design, since PCBs are now commonly available.
 
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My buddy has a huge capacitor store Hiendparadise on ebay so i do not have a problem about capacitors :) I already have one bag of 200pcs of nichicon pl 2200uf 25v ultra low esr long life capacitors. I sometimes have difficulty about finding original transistors. I will use mkp1848 70uf paralelled so 140uf per channel for my 4 ohm fullranges. Just will go for symmetrical supply for 13 inch woofers ( they are 93dB so not need much power ) I am just looking for highest quality and purity.I remember single supply Jlh have some sonic advantages and i have opportunity to use film capacitors at output so i will use them for fullranges. Jlh is also sold more than pass amps like F5 or F4 or other aleph amps and more popular on aliexpress and ebay so i want to use them as main amps.
 
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Perhaps there is some misunderstanding but the output capacitor for the full audio range, requires approximately 2,700uF when used with actual 8R loudspeakers, more with lower impedance speakers. You can increase that to 4,700 uF to suit 4R speakers and you can supplement that with large film caps for the high frequencies if you wish, but few credible listeners report any improvement over suitable high quality electrolytic capacitors.

However, the real problem (the elephant in the room) is that power requirements for bass frequencies also increase rapidly as the frequency falls below 100Hz. This is where JLH'69 and other small amplifiers begin to struggle. 10W/8R power just isn't enough power to reproduce strong, deep bass. Attempts to increase the power or size of the design also seem to have been unsuccessful, or we would have seen lots of high power JLH design amplifiers out there in the market. So maybe we should get used to a lack of sub-bass or just listen to music that doesn't contain any.
 
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Perhaps there is some misunderstanding but the output capacitor for the full audio range, requires approximately 2,700uF when used with actual 8R loudspeakers, more with lower impedance speakers. You can increase that to 4,700 uF to suit 4R speakers and you can supplement that with large film caps for the high frequencies if you wish, but few credible listeners report any improvement over suitable high quality electrolytic capacitors.

However, the real problem (the elephant in the room) is that power requirements for bass frequencies also increase rapidly as the frequency falls below 100Hz. This is where JLH'69 and other small amplifiers begin to struggle. 10W/8R power just isn't enough power to reproduce strong, deep bass. Attempts to increase the power or size of the design also seem to have been unsuccessful, or we would have seen lots of high power JLH design amplifiers out there in the market. So maybe we should get used to a lack of sub-bass or just listen to music that doesn't contain any.
I already use it for fullrange but it is bass assisted fullrange and 140uF caps make 284Hz cutoff frequency. Below 284Hz bass speakers will play. No i will not parallel film caps with elko. I will only use film caps for fullranges(wideranges).I am already using with passive line level crossover (pllxo) It needs 4 channel amp.
Yes i agree Jlh may not be enough for bass speakers for deep bass like 30Hz.
 

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I see that JLH kits have 100k input impedance (they put 100k resistor in the input) It may help to put smaller capacitor on the input.And also can put much smaller value and can use Ero kp1830 series small value film foil capacitor when using as tweeter or midrange amplifier.
 
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I searched but could not find input impedance of Jlh amplifier.It is needed for true pllxo design. Could you tell it ? Is it 20k?
The input impedance of kit products is usually a nominal figure, i.e. not exact, only approximate or the minimum, given the mix of designs and condition of components we find in amplifier input stages. The designer should provide a standard, specified 10k input impedance but that could even be 100k, since it doesn't need to match in order to reproduce audio. As long as the input impedance is not much lower than the source impedance, it could still provide acceptable but not necessarily the best, low noise and linear audio.

This is a problem with DIY design and many kits - standards are often unknown, ignored or misunderstood.
 
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As Ian suggests, you need a large capacitor for good bass reponse in the JLH. Many amplifiers in the 1970's with single ended output (and I use this term to mean a single phase output as opposed to differential - and SEPP is a commonly used acronym) used output capacitors of 2.2mF. While that gives a nominal 10Hz -3dB into 8 ohms, it really isn't that good for low frequency response. 22mF is more like it but then the other capacitors may limit the response and have to be increased as well.
Regarding the input impedance of the JLH, he biased the input transistor with two 100k resistors so they act in parallel to give 50k. Then there is the impedance of the transistor. For a BC557B input device with a gain of 200 (say) and a current swing of 200uA (peak) the RMS input current is 0.7uA for 900mV input or an input impedance of 1.2M which brings the overall input impedance to about 48k.
I would not recommend using that for bandwidth control in a multi-amp setup because small capacitors for high frequency range are likely to increase noise. Best use a pre-amp to split the channels and keep each main amp with a large input capacitor to keep the impedance low.
 
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The "strongest, deepest bass" I get with my 2 W SE;-)
May be, "strong, deep bass" has nothing to do with "power" but with cleanness, clearness;-)
Test your thoughts: As a DIY, I assume you have a multimeter, specifically an older moving coil type with an AC voltmeter range or, if you have access, an oscilloscope to observe the supply voltage whilst the amplifier is producing "strong, deep bass" into a load. Use a large, fixed 4-8 ohms resistor load of at least 10W rating because it will get hot :redhot: Immersing it in clean water will help but be careful with electrical safety. One side (earth) of the load resistor should remain securely grounded.

At maximum output level and a deep bass tone below 50 Hz, maybe you can now see what your amplifier is really working with when you compare loaded to unloaded output and DC supply voltages, like when you turn up the volume and find the problem of not having enough power capability e.g.- the power supply voltage sags when the amplifier is driving a suitable loudspeaker. Audio test tones are available on the internet if you don't have an audio oscillator or similar instrument. e.g. Audio+test+tones&oq=Audio+test+tones&aqs=chrome..69i57.8012j0j7&sourceid=chrome&ie=UTF-8#fpstate=ive&vld=cid:767c1c64,vid:nklzAUrXSuM

In reality, we can't know that we have plenty of deep bass unless our sound field is long enough to sustain it. That generally requires a large room + suitably high power). Conversely, higher frequencies are directional, reflect from surfaces and only require small spaces due to shorter wavelengths. We can't ignore the physics of sound but if very low power and a small sound field and audio frequency range is enough for you, then whatever hi-fi bandwidth or power limits are assumed for your audio system will be irrelevant.
 
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;-)
The simplest answer: "strong, deep bass" is an acoustic description and estimation "only". It's all about perception.
Nobody - I hope - needs bad sounding, high distorting lowest tones;-)

Aside: the vast majority try to get rid of uncleanliness ("grayness") with bass ("blackness"). But they only lack cleanliness;-)