I don't think blocking distortion affects JFETs as the gate is insulated from the channel. It's something that only really happens with valves man 
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You're pretty much confirming the technical problems with this preamp. 4% THD is pretty digusting TBH. I'd imagine it would be much much worse at higher frequencies too. 0.1% is pretty much the maximum acceptable at moderate signal levels IMO.
So there we have it, it's been proved that the BHL is a grossly inferior circuit.
.You're pretty much confirming the technical problems with this preamp. 4% THD is pretty digusting TBH. I'd imagine it would be much much worse at higher frequencies too. 0.1% is pretty much the maximum acceptable at moderate signal levels IMO.
So there we have it, it's been proved that the BHL is a grossly inferior circuit.
I don't know about BHL but stock FSP is 0.02% at 0dB 300mV RMS and 1.25% at +20dB. Now think of what THD a cartridge will produce at +20dB modulation when excellent expensive MCs give 0.5% at 0dB 1kHz test disc on FFT. Only run a +18dB torture track for antiskating set and be lucky if few great carts will not skate it out to the lock groove.
Please take those SPICE numbers with a big grain of salt!
Not so fast!
I'm not sure I'm getting accurate results. I'll keep working on it. If anybody knows of a relatively easy way to use the .tran directive in combination with the .four directive in LTSpice to get reasonably accurate results, please let me (us) know. The problem at the moment is that if I follow a method that is supposed to be wrong, I get what look like usable results. If I follow a 'correct' method, everything comes out showing 2.7% THD (I know that can't be right).
I used the same ('wrong') method for both examples in my earlier post, so perhaps the comparison is valid, if not the absolute numbers.
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Not so fast!
I'm not sure I'm getting accurate results. I'll keep working on it. If anybody knows of a relatively easy way to use the .tran directive in combination with the .four directive in LTSpice to get reasonably accurate results, please let me (us) know. The problem at the moment is that if I follow a method that is supposed to be wrong, I get what look like usable results. If I follow a 'correct' method, everything comes out showing 2.7% THD (I know that can't be right).
I used the same ('wrong') method for both examples in my earlier post, so perhaps the comparison is valid, if not the absolute numbers.
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I don't think blocking distortion affects JFETs as the gate is insulated from the channel. It's something that only really happens with valves man
Hmmm... If that's the case, then this Boozhound thing isn't all that bad. It'll distort on big peaks, but as Salas pointed out, so will the cartridge.
The Boozhound just needs a higher voltage supply and adjustments to suit. Then it will have better headroom, and lower distortion. I think the sim showed decent distortion levels for a circuit running open loop with inadequate B+ voltage. I'd say it has potential.
BTW, that tube preamp in the comparison has no loop feedback either. It's pretty much the same topology as the Boozhound, just with tubes. Eli D's RCA-Redux is also that same topology.
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I seem to have provoked an argument Hopefully it will be constructive.
I would have liked to order a completish kit from Salas but I missed the group buy.
I was going to battery power the Boozhound, what the maximum supply rail I could safely use, if I went that way? Would it be possible to modify the Boozhound to be similar to the circuit Kindly published by Salas.
It certainly won't be my first soldering project, or my most complex. I've been building and modifying HiFi and other bits and pieces since the 80's including a power amp and a Audio Synthesis DAC. Just lack the knowledge to design anything much.
Also lack access to oscilloscopes , signal gen, etc. Just a soldering iron and a DMM!
Looking into the laptop based oscilloscopes though, or borrowing one.
How good are the phono boards in the Naim pre-amp in comparison? I've always felt the Naim pre-amp was the weak point in my system, hence the LDR pre-amp from Rudi.
I would have liked to order a completish kit from Salas but I missed the group buy.
I was going to battery power the Boozhound, what the maximum supply rail I could safely use, if I went that way? Would it be possible to modify the Boozhound to be similar to the circuit Kindly published by Salas.
It certainly won't be my first soldering project, or my most complex. I've been building and modifying HiFi and other bits and pieces since the 80's including a power amp and a Audio Synthesis DAC. Just lack the knowledge to design anything much.
Also lack access to oscilloscopes , signal gen, etc. Just a soldering iron and a DMM!
Looking into the laptop based oscilloscopes though, or borrowing one.
How good are the phono boards in the Naim pre-amp in comparison? I've always felt the Naim pre-amp was the weak point in my system, hence the LDR pre-amp from Rudi.
The BHL and FSP are much different in critical stages topology, so is the Pearl. JFETs, passive Riaa, no loop feedback is the common frame but you can not copy & paste bits from one to the other. As for GB, sorry to hear you missed out, maybe ask Tea-Bag if his got any extra left after he had shipped the bulk these days.
The Naim pre-amp will be much, much better than the BHL phonostage. Maybe you should invest your time and money into another part of your system? There are lots of other things you can build
My main speakers are Martin Logan Sequel IIs recently repaneled, I love the way these sound (albeit the rooms too small!)
My main source is a Heavily modified Sony DVP NS-9100ES (still planning to fit some Zapfilters or similar). My Turntable is a Pro-ject 2.9 wood with an AT440ml fitted (haven't started tweaking it yet, thinking about isolating the motor). I also have an Audio synthesis DAC using PCM63k and powered by multiple battery power supplies (one for ach stage and each channel)
The Main power amp is an ETI design I built many years ago and have rebuilt again and again different wiring etc.
My speaker cables are Kimber 8TC (biwired) and my interconnects range from Nordost Red Dawn, Kimber, and some home built pure silver with Ptfe tape insulation.
The next plans, after the LDR pre-amp and some phono stage, are to actively crossover (removing most of the passive crossover components) the Martin Logans and use DSP room correction, and add the Zapfilters to the SACD player.
Amongst my collection of HiFi are a pair of O'Heocha D2AL1 ( http://www.amazon.co.uk/Oheocha-Acoustically-Optimized-Exclusive-Aluminium/dp/B005O9JVVQ ), feed by a pair of Meridian 205 (recapped a while back, probably need doing again using better caps) through a Lexicon DC2 just to use for the TV room temporarily.
A Rotel RB991, Little done to it except schottky diodes and bypass caps, (feel it would benefit from separate low current PSUs for the driver stages)
I will probably use this to power the bass units in the Martin Logans.
Also have quite a few other bits lying around in my Cupboards like a defunct (laser dead) Sony CDP337esd and a dying 227esd, a throrens tuner, a Roksan Kandy tuner (bought listened for a very brief period and removed to make space in the rack.), an old Leak tuner (not the valve one)
and probably some other things long forgotten!!
I would like a decent phono stage which could be built without fault finding.
One option would be to remove the Naim phono boards and battery power them, but I would like to build a better one if possible, and sell the Naim complete.
Is this feasible or am I mad????
At the end of the day the BHL circuit is severely limited everyone knows that, however I repeat - it is pleasing people - regardless of its technical issues (and those who've got a bee in their bonnet over it) and its a very simple kit to build and IMO is a very good starting phono. You can experiment with it all you like...
Dont loose sight of - just have some fun for goods sake and not take this simple cct too seriously...
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Accurate distortion levels or accurate qualities not predicted by distortion but rather the noise that may be contributing to it? Honestly headroom is the good arguement you got, and the rest really isn't telling me anything about good/bad sound predictions. What makes something sound good? That is an interesting question and it's been proven a gazillion times that distortion isn't an indicator that's very useful once a circuit is beyond simple problems.
R12.
I would be interested in hearing comparisons against commercial products as they tend to give ( a more?) standard baseline to work from.
The only real Phono stage I have experience of is the Naim. The op-amp based kit seemed to be "comparable" to a Pro-ject phono stage, which I would hope to better by a design I build myself.
The Salas phono stage seemed to compare favourably against some top end gear.
The only real Phono stage I have experience of is the Naim. The op-amp based kit seemed to be "comparable" to a Pro-ject phono stage, which I would hope to better by a design I build myself.
The Salas phono stage seemed to compare favourably against some top end gear.
Could be your time step is too coarse. This results in waveforms that are lumpy and misshapen, they're basically under sampled. Try turning off compression in the preferences and for your .tran command, make the timestep smaller. 1 us? 100 ns? Find the balance between simulation time and accuracy.
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