Excellent Solid State or Hybrid Monoblocks Recommendations

A Neurochrome 365 or a Purifi EIGENTAKT Class D Amplifier are both able to be produced as a Monoblock.

I know the 365 and the lower powered versions down to the 65 very well, to the point, I do believe the 65 might be my last owned Amp' when I come away from the present system.

I also know an owner of the 365 with a few Mod's incorporated who has been recently familiarised with a Purifi EIGENTAKT, the result being they are very impressed and are now building their own one with a few mod's learnt from an Amp builder/measurement group.

These can be housed in an very nice aesthetically pleasing enclosure and might require an EE's assistance.

I would bet all in any of these Amp's would come in at $2.5K max to build as Monoblocks.

In relation to the Commercial World of Retail Pricing, the BOM for these Amp' Types alone, if attached to a retail product, would put Amp's being supplied retail into the $20K - $40K zone, especially if a very fancy aesthetic was also part of the pricing for the upper end in the suggested price range.

The first Time I heard a Neurochrome Amp' it was on a £200K+ System, where the Soulution Power Amp' at approx' £50k was in use for approx' 2 Hours as the base Amp' used for Phonostage Demonstrations.

The Soulution was swapped out and replaced by the Neurochrome. For the 3-4 Tracks allowed for the Demonstration, the Neurochrome did not show any signs of having a Amp' immediately available to be put back to use, that could show it to be a underperformer, even though it did have a slight variation to how it delivers the end sound.  

On the same occasion following the Neurochrome, an individual known to have very adept EE Skills and has produced very attractive audio demonstrations, put into the system, their £400 purchase, that was a 4 Box Class D Monoblock imported from China. The builder had spent approx' £100 doing their own design hooks for the schematic/topology.

The system owner who also has a audio retail business claimed he might as well throw in the towel.

The Chinese Import was not as good as either of the previous Amp's, but if an individual was able to receive a Demo; of the Import Amp' and the Soulution, it would be some sales person that convinces a person to spend the extra £49500 on the Soulution Amp'.

In relation to the Neurochrome vs Soulution, the individual in the Demo' would need to be a Soulution die hard fanboy, to decide the Soulution was the one to spend the extra £47500 on to take it home.

In no way am I knocking Soulution Amp's, I have as an estimate heard them in use in the same system, for near 20 Hours of play time. I would be very very Happy to use one.

Have there been many changes to the PS Audio BHK 300 monoblock amplifiers over the past few years?

@jaymark Seems like there were some revisions that affected early units.  In case you're interested, PS Audio has a good forum where you can even find old posts from BHK himself.  Here's the thread about revisions:

PS Audio Forum: How To Tell If You Have The Latest Version Of BHK Signature 250, 300 or Preamp???

Do PS Audio BHK 300 monoblock amps require a 20 amp line?  If not require one would the sound better with one? Or is a 15 amp line sufficient?

15amps should be okay, but 20amps would likely be preferable if you're running off of a single circuit.  I run through a few conditioners and the Furman SPR-20i averages ~2 amps for the BHK 250 at moderate listening levels.  I'm assuming with all equipment powered and running BHK 300s, you could be pushing ~10 amps continuous draw for everything, but, for reference, the BHK 250/300 uses 10 amp fuses so you'd never surpass 10 amps per amp even at full throttle.

@pynkfloydd many thanks.  I was going to pick up a pair of used PS Audio BHK 300 monoblocks used then got cold feet when the seller did not know how old they were and the serial numbers were non-sequential.  So I ordered a brand new pair from P SAudio and traded in one of my amps in my collection.   Glad to know I should be OK with 15a lines.

I suspect that the gan fet is a chunk of this progress assuming it is well implemented.  I am gonna pick up some class D monoblocks in the near future.....

@jaymark What GaNFETs bring to the table is low noise. You really do want a class D amp to be low noise because that noise can leak out through the air or on the AC power line. It can get into other components and mess with them. So its not enough that the class D amp meet EU Directives for low noise (or in this country FCC 'part 15'); it needs to be a lot lower so things like digital audio, FM radio, a phono section, don't get upset by the operation of the amp in proximity.

A major source of noise in class D is something called 'parasitic inductance' which is might be a lead of a part or a trace on a board that is long enough that its able to resonate and transmit noise like an antenna. GaNFETs typically don't have leads making them inherently lower noise than MOSFETs, which usually do have leads.

GaNFETs also tend to have a very low 'On' resistance, so low that a lot of the time they don't even need a heatsink, because with lower on resistance there is also less energy dissipated in the device. The inherently faster speed of the devices also means less deadtime to accomodate their operation. Deadtime is a period of waiting in the circuit so time is given for one device to turn off before the other is turned on (otherwise the devices can heat up very quickly and fail). Deadtime contributes to distortion- reducing it can make the amp smoother and more detailed.

many thanks.  I was going to pick up a pair of used PS Audio BHK 300 monoblocks used then got cold feet when the seller did not know how old they were and the serial numbers were non-sequential.  So I ordered a brand new pair from P SAudio and traded in one of my amps in my collection.   Glad to know I should be OK with 15a lines.

@jaymark Any time and congratulations!  Bascom King's designs are so well-regarded that you can't go wrong, especially since these ended up on many "best of" lists.

You may also enjoy the tube rolling threads on PS Audio's forums:  PS Audio - BHK 250 / 300 Tube Rolling Thread

Something really nice about the BHK amps is that they accept the 6922 variants without any special configuration.  Bascom replied on one of the PS Audio threads and recommended the Tungsram PCC88, but it's a very laid-back tube.  I went on a tube binge and have tried ~15-20 different sets, so let me know if you'd like any tube suggestions.  I also had a positive improvement from Acme's silver ceramic fuses, which were ~$130 per amp for the set of 6.

Hope to hear your impressions after you're able to set your new monoblocks up!