I've actually used the BHL and compared it to a couple different phono stages.
The BHL phono stages has a couple weaknesses, namely a lot of capacitance at the input, the inability to drive long cables and it doesn't like power supply noise. If these things don't bother you and you use batteries it's a very good sounding phono stage. If you use a MM cart that likes low loading you may not like the BHL.
The THD is high but it's mostly 2nd harmonic. Which means it doesn't sound like high THD.
I've use a few 2134-IC based phono stages. I liked the BHL better. Sounded "blacker" and more 3D.
I think the PIO caps in the BHL kits make it sound a bit relaxed and dull. I changed them to poly.
I went from the BHL to the Salas phono stage which is by most accounts close to the top in terms of performance. The difference was more detail, it sounded "faster" and more open. But the overall tonality was similar.
Is the BHL not good enough for a VPI prime? I don't know....depends on the cartridge I suppose. It's not a bad phono stage, and I think it's better than people are describing here. I would want something better though and you should probably be using a MC cart on that table.
The BHL phono stages has a couple weaknesses, namely a lot of capacitance at the input, the inability to drive long cables and it doesn't like power supply noise. If these things don't bother you and you use batteries it's a very good sounding phono stage. If you use a MM cart that likes low loading you may not like the BHL.
The THD is high but it's mostly 2nd harmonic. Which means it doesn't sound like high THD.
I've use a few 2134-IC based phono stages. I liked the BHL better. Sounded "blacker" and more 3D.
I think the PIO caps in the BHL kits make it sound a bit relaxed and dull. I changed them to poly.
I went from the BHL to the Salas phono stage which is by most accounts close to the top in terms of performance. The difference was more detail, it sounded "faster" and more open. But the overall tonality was similar.
Is the BHL not good enough for a VPI prime? I don't know....depends on the cartridge I suppose. It's not a bad phono stage, and I think it's better than people are describing here. I would want something better though and you should probably be using a MC cart on that table.
2nd harmonic distortion still means lots of intermodulation distortion. It would be nice if it was only harmonic distortion but it never is if you're not listening to pure tones. The 2nd harmonic would be the strongest component in this preamp as the FETs follow a square law in terms of Id vs Vgs.
I had a little look at the Deluxe version about 15 minutes ago and it really isn't much of an improvement as far as performance is concerned. It still will have high sensitivity to power supply noise, reduced headroom (even more so with the gain increased) and poor linearity. I would not say that it's suitable for MC carts as there is a 100R resistor in series with the pre-stage for MC inputs which will swamp the noise of the low impedance low output coil.
I'm afraid I cannot comment on how 'black' preamps sound...
I had a little look at the Deluxe version about 15 minutes ago and it really isn't much of an improvement as far as performance is concerned. It still will have high sensitivity to power supply noise, reduced headroom (even more so with the gain increased) and poor linearity. I would not say that it's suitable for MC carts as there is a 100R resistor in series with the pre-stage for MC inputs which will swamp the noise of the low impedance low output coil.
I'm afraid I cannot comment on how 'black' preamps sound...
To be clear, I am using a MC cart. I use the BHL phono amp with the BHL headamp. I like the phono quite a bit but the headamp is really fine. I have no desire to upgrade the headamp section. I did the headamp first and was so floored by it that I got the phono amp too, which was nice. But the headamp is a much better performer than the phono amp IMHO.
FYI the cart I have on there is a 103R with an aluminum body and a sound smith ruby cantilever/line contact stylus. It punches way above its weight!
I'll look into the other options you mentioned, thanks!
Nate
if you are looking at DIY phono stages I would look at the Pass Pearl 2, salas phono, phonoclone and paradise phono.
Yes, your phono stage is probably the weak link, the DL103 kind of a preference choice, I have never had one. The good thing is you get around the input capacitance issue with the MC step up.
All the stages mentioned above are probably better. But there is always something better out there...if you like the BHL that is great. If you are like me you will probably get the itch to change something in 6 months anyways. If you want to change something in the BHL the cap between stages is a good place to start. I believe it is .1uf. But the BHL is far from terrible and probably better than a lot of commercial phono stages out there t the $500 level.
I thought batteries were a pain in the BHL. I like to leave my preamps on all the time. It bothered me to always have to monitor voltage, etc.
Yes, your phono stage is probably the weak link, the DL103 kind of a preference choice, I have never had one. The good thing is you get around the input capacitance issue with the MC step up.
All the stages mentioned above are probably better. But there is always something better out there...if you like the BHL that is great. If you are like me you will probably get the itch to change something in 6 months anyways. If you want to change something in the BHL the cap between stages is a good place to start. I believe it is .1uf. But the BHL is far from terrible and probably better than a lot of commercial phono stages out there t the $500 level.
I thought batteries were a pain in the BHL. I like to leave my preamps on all the time. It bothered me to always have to monitor voltage, etc.
A good preamp should have good enough PSRR so as not to need batteries 
.
There are plenty of good phonostages under $100 that beat ones priced at $500. Cambridge Audio springs to mind, with the added benefit of having a rumble filter included in the design, which is a must have IMHO.
I'd say the coupling capacitor is the least of your worries with the BHL kit! If anything it gives a bit of roll-off to low frequency noise (always a good thing). Since it has a rather large DC bias on it, then it's not going to cause any significant distortion at sensible levels, and this would only be the case if it's polyester anyway.
If I were you I'd modify the BHL preamp to run with feedback EQ instead of passive EQ, which would be fairly straightforward and ensure you don't run out of headroom at HF.
.There are plenty of good phonostages under $100 that beat ones priced at $500. Cambridge Audio springs to mind, with the added benefit of having a rumble filter included in the design, which is a must have IMHO.
I'd say the coupling capacitor is the least of your worries with the BHL kit! If anything it gives a bit of roll-off to low frequency noise (always a good thing). Since it has a rather large DC bias on it, then it's not going to cause any significant distortion at sensible levels, and this would only be the case if it's polyester anyway.
If I were you I'd modify the BHL preamp to run with feedback EQ instead of passive EQ, which would be fairly straightforward and ensure you don't run out of headroom at HF.
I agree with you about the batteries thats why I switch in ext power via relay to keep everything thermally stable and switch to batts only for listening.
The SALAS Simplistic is my next build.
LM317 would be a better choice of regulator, far less costly, less demanding on the transformer and filter capacitors and if you configure it with a capacitor in the feedback loop the ripple rejection is very hard to beat.
If I were you I'd invest my discrete components in a muting circuit. The BHL will generate up to 10V of thump upon switch on. Easily enough to upset some preamps.
If I were you I'd invest my discrete components in a muting circuit. The BHL will generate up to 10V of thump upon switch on. Easily enough to upset some preamps.
Agreed SALAS' shunts are very good indeed. It was a toss up between SALAS shunts or batteries and I choose batteries just for fun. I may revisit this later...
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That's pretty awesome. You could make a nice regulator for valve preamps with that little chip. Must remember to add it to my next order from RS for some tinkering.
If you were to design a 28V supply with the 317 then you might have a some trouble with the input voltage exceeding the maximum 37 volts at startup, the 783 would render that problem null .
Battery powered non-portable preamps for HiFi... Very telling of the preamps ability to cope with even the tiniest amount of supply fuzz. If you need to run it off a battery then you should probably concentrate your efforts in building a different preamp . You know you've gone off the rails when your regulator is more complicated than your audio path .
If you were to design a 28V supply with the 317 then you might have a some trouble with the input voltage exceeding the maximum 37 volts at startup, the 783 would render that problem null
.Battery powered non-portable preamps for HiFi... Very telling of the preamps ability to cope with even the tiniest amount of supply fuzz. If you need to run it off a battery then you should probably concentrate your efforts in building a different preamp
. You know you've gone off the rails when your regulator is more complicated than your audio path .One thing I forgot to mention earlier that should be of considerable interest to all those who are using the BHL is that I corrected a design error in the RIAA stage that may contribute to the differences in listening experience between builders..
The error lays with R5 and R8 - the Rev.3 the build notes quote R5 = 22k1 for passive RIAA (this is the calculated unloaded value?) yet this value does not account for the Zo of the input stage at 3k. Also R8 should be 3k2 not 3k... If R5 is not reduced to 19k1 and R8 = 3k2 then the network time constants are thrown off..
I havent thrown this on a INV-RIAA test rig yet although I do plan too when Ive got a weekend free sometime soon..... I'll get back to y'all when I have relevant measurement data to present.
I do recommend BHL builders investigate this error and give it a try..
With my RIAA "corrections" installed I'm playing vinyl that I am VERY familiar with and I am very pleased with the listening experience I'm getting out of this - there is nothing of concern that I can or cannot hear, its very balanced and neutral and very quiet.
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I've been using the BH MC pre for about 8 months now and have no reason to try anything else. PS is 2 9v batteries, the first pair lasted about 6 months. I thought about trying Li batteries but charging them is a pain, and I like not needing a holder for the 9v. I have a single snap connector soldered to the board, and plug the 2 batteries in side by side and use an alligator clip as my on/off switch on the two other terminals.
Yes, but 50R is not all that significant. if you compare it to the transconductance of the FET. 22mS works out to an equivalent source impedance of about 45 ohms, so while that is enough to double Rd it still wouldn't be in the 60K region.
A quick look at the datasheet shows that without any source degeneration Rds is about 8K or so within a range of 4-12V. Adding the 50R source resistor would perhaps increase this to 16K. That would give you an output impedance of roughly 2.6K.
So I'm a little puzzled as to where this 3K figure came from .
A quick look at the datasheet shows that without any source degeneration Rds is about 8K or so within a range of 4-12V. Adding the 50R source resistor would perhaps increase this to 16K. That would give you an output impedance of roughly 2.6K.
So I'm a little puzzled as to where this 3K figure came from
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