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Blue Hawaii BJT Build thread


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1 hour ago, headinclouds said:

Well done Pars - although a hole in the skirt is not very bright on its own. 

(I'm a bit paranoid about a Chinese clone coming out next week, ref. earlier discussion.)



I feel that my question will choke you. I was just curious

I haven´t  intention of setting up a production chain in China.

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  • 5 months later...
  • 2 months later...

I'd like to chip in here. On different tracks I sometimes had a slight preference for the sound of the GG or the BH, but overall I had a slight preference for the sound of the BH.

This impression was pretty fairly arrived at as each amplifier had the same power supplies (all golden ref), wiring, volume attenuator and casework.  The GG did have  450v supplies and the BH 400v.  The volume was equalised as accurately as possible.

It was a wrench but I had to part with one of my babies as couldn't justify keeping both, so the GG has gone.  I did hear the new 009S with it and the combination was, on a short hearing, near perfect.

I have noticed after many builds of Kevin's designs my preference has been for the versions with tube OP stages.


Edited by headinclouds
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Hard for me to say that I prefer one of my amps over another in general.  Depends on what I am listening to.  I tend to use the BH BJT the most, following by about equal usage of my Carbon and my SRX-Plus.  But just as with children, I would never part with any of them!  SRX-Plus remains my 'most admired' amp because 1) it was my first build, and 2) it is such a simple design yet sounds amazing.  

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18 hours ago, headinclouds said:

I'd like to chip in here. On different tracks I sometimes had a slight preference for the sound of the GG or the BH, but overall I had a slight preference for the sound of the BH.

This impression was pretty fairly arrived at as each amplifier had the same power supplies (all golden ref), wiring, volume attenuator and casework.  The GG did have  450v supplies and the BH 400v.  The volume was equalised as accurately as possible.

It was a wrench but I had to part with one of my babies as couldn't justify keeping both, so the GG has gone.  I did hear the new 009S with it and the combination was, on a short hearing, near perfect.

I have noticed after many builds of Kevin's designs my preference has been for the versions with tube OP stages.


My personal experience matches headinclouds' . All my amps (GG, BH, Carbon, KGSSHV, CFA) are all powered by the exact same PSU (Golden Ref. HV and LV). 

I have not listened to my BH for some time. Going by memory, I may have a difficult time picking a favorite between my tweaked Megatron with the right tubes and the BH.  Like Geoff said, sometimes it's the right horse for the right track!


PS. Forgot to mention, my BH is the version with the FET not the BJT but has the updated cascoded CCS. Don't know if it matters much sound wise.

Edited by mwl168
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I was thinking about this and I really do not have any favorites. I tend to use combinations that I think work very well, for example the KGST-L700, SRX-Lambda, BH / GG-007 … Carbon is my "precision measuring instrument"

Now I'm using the Megatron a lot for the valves  but I really enjoy it with anyone.

I agree with Geoff.

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  • 7 months later...

Hi, im planning t build a blue hawaii using kgbhver6sbipolar amp boards which has constant current and the kgsshvpssicfetdual2new power supply - which does not have delayed start but I will make my own...

I am trying to get a reasonably definitive answer (if any exists) on the transformer specification...

the power supply board and amp baords say on the silkscreen

2x 6V 4A for the heaters, I purpose 2x 6.3V 4.5A for the transformer

18-0-18V for the low voltage I purpose 0.2A.... is thie going to be sufficent???

2x 360V  for the high voltage. It has been suggested to me that if I am going to run at +-400V DC then 330V is fine for the transformer... so I purpose 330V 0.3A is this going to be sufficent?

regards and thank you



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  • 1 month later...

For anyone building a blue hawaii, here are the current draws for my build after 5 minutes of power on, rounded up to the nearest mA. These figures provide no margin for variation, to headroom for inrush on power up and should not be considered minimum specs for the transformer... 

PSU board set to 400V output (actual around 404V)

constant current on the amp boards set to 20mA per valve

inputs shorted to ground

no headphones attached

groove tubes el34

kemet long life 470uF caps @ 550V for B+ and B-

Boards used: 

amp Blue Hawaii kgbhver6sbipolarinc 

PSU kgsshvpssicfetdual2new (single board version 1.6 with no delayed start cpc1117n that appeared in ver 1.7)total for both channels:

-15VDC line draws 10mA

+15VDC line draws 11mA 

+400VDC line draws 81mA

-400VDC line draws 128mA

EACH 6.3VAC line draws 3.1A 

Primary side current draw 0.67A @230VAC

All Measurements made on a Brymen bm869s multimeter. NOTE With @230V  primary the inrush current is significant and will blow a 3A fast blow fuse on power up, and blow a 4A fast blow after half a dozen power ups (tested with no B+- delay circuit). With a delay circuit 3.15A Timed fuse looks good. 

transformer I used (which is overkill, but as a result the transformer generates very little heat. )

330VAC 300mA

330Vac 300mA

36V AC centre tapped 200mA 18v-0-18v

6.3VAC 4.5A

6.3VAC 4.5A

Now I have measurements I would say that the transformer could be scaled down to somthing like

330V 250mA

330V 150mA

+18V centre tap -18V 50mA

2x 6.3V 4.5A

I hope this post will help someone.




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Blue hawaii build notes for the kgsshvpssicfetdual2new PSU

The kgsshvpssicfetdual2new is based on version 1.6 of the kgsshv psu single boards and does NOT have the cpc1117N or resistor required for simple B+,B- delayed start. (it’s still possible to implement delayed start but it requires a relay(s) which the cpc1117N avoids). In all other ways its similar to the v1.7 single boards. The single boards put the b+ on one board and the b- on another and split the -+15V and bias between them.

The kgsshv ps dual has all the dc voltages required to power the blue hawaii and apart from the notes above is topologically and componentry identical to the single psu boards. The notes bellow applies to BOTH the single and the dual psu boards.

Construction is straightforward other than

1. the silkscreen shows 15-0-15VAC input for the + and 15VDC outputs, Since the -+15V output is a simple DC supply with a bridge rectifier and voltage regulators 15-0-15VAC is NOT sufficient to provide -+15V output... I have verified this using a variac. There is about 0.6V drop across each diode in the bridge *plus* the voltage regs need between 1V and 1.5V more input DC than their output in order to regulate properly. so 18-0-18AC is actually required to get a properly regulated -+15VDC output... Any more VAC input will be converted into heat by the voltage regs. However, with 18VAC-0-18VAC centre tapped input the voltage regs run very cool with the small heatsink they are bolted to.

2. the blue hawaii amp boards -400VDC lines draw more current than the +400V lines. If you connect a single channel up to the psu board for testing there will be no problems. Connecting two channels results in the -400V line on the psu going into current limit and the voltage dropping to (im my case) about -175VDC. The fix is fortunately easy. The 5.1ohm 3W or 5W resistors are the current sense resistors for the  over current protection. On the -400V psu side either replace the 5.1ohm resistor with about 2.6ohm or similar wattage and type or parallel another identical 5.1ohm around the existing one. The +400V does not need modification. the lower the resistors value the more current supplied before the current limit cicruit activates. I don’t have anyway to variable load a line that has such a high voltage but I would guesstimate that the 5.1ohm resistor current limits at about 100mA since two amp boards +400V together draw around 81mA and there is no problem with 5.1ohm and 2 -400V boards draw between them around 129mA and that causes current limiting with 5.1ohm sense resistors.

3 make sure none of the metals tabs on the transistors are shorted to the heatsink/L bracket that mounts to the heatsink. Use electrically insulated spacers between the back of the transistors with metal tabs and the L bracket/heatsink AND use a nonconductive gromet to insulate the bolt from the transistor. The psu transistors do not get that hot with a reasonable size heatsink attached.

4. if you are building in a u2 high case the largest main psu caps you can put in are Kemet 500V 470uF long life at 65mm tall. Beware they also do an 80mm tall 470uF cap - this will NOT fit in 2u. Similarly 680uF caps at 500V are 80mm high and will not fit.

5. if you want to check the bias is 580V use the bias test point. Dont measure at the bias screw terminal. Why, typical multimeters have a 10M ohm input impedance and assume whatever they are measuring across is much less than 10Mohm... this is NOT the case for the bias line which has a 4.7Mohm resistor. result the multimeter will NOT give the correct voltage reading between the ground screw and the bias screw. Measure from the bias pad nearby to the ground screw. Also, don’t measure the bias with headphones attached.

6. there is only one screw terminal for +400V, -400V, +15V and -15V so you will need to connect two wires to each screw terminal. This limits the gauge of the wire. Also make sure you are screwed the terminal down well, its easy to have one wire firmly affixed and the other one lose.... 

7. to adjust the B+ and B- lines the two 390K resistors (R8 and R9) in series with the 20K resistor (R7) just after the 1N007 diode that have the 0.047uF cap across them need to be changed. Approximately (for my psu) I got the following

442K for 450VDC (note requires a transformer with 360VAC output to have enough voltage input to get proper regulation)

390K for 404VDC (transformer 330VAC or more output)

365K for 375VDC (transformer 310VAC or more output)

the approximate equation for me was the total of the 2 resistors in ohms/(20,000-700)*10     

(the 20,000 is the resistor in series with the resistors you are changing, the 10 is the output of the voltage reference LT1021-10), the 700 is the fudge factor to make the numbers accurate for me... (variation in voltage reference, variation in the 20K resistor etc etc...)

8. To test for proper regulation connect a volt meter to the nominally +-400V output and a ground screw terminal and either power the transformer from a variac OR if your variac can go high enough you could go from the variac output into the 300VAC input of the psu. There is no need to have amp boards connected at all and its safer if you dont. Slowly increase the AC and you should see the DC output rise. At some point increasing the variac by some volts will result in very small output increases (in the order of few milli volts) now the psu is regulating. Measure the 330VAC input of the psu and that’s the minimum transformer output voltage you need for regulation. Both the + and - 400V sides of the psu should have similarly behaviour and similar minimum VAC input requirements since they are almost identical in topology and are identical in components.

9. I would recommend initially testing the psu board without amp boards connected in case voltages are way off. However, with no load on the psu the b+ and b- lines, they will take some minutes to fall to 0v and with no headphones the bias line will stay high for a long time. Fortunately the bias line can be discharged just by connecting a multimeter to it and ground and set to DC volts. Even a meter with 10Mohm input impedance will drain the bias line in a few minutes. the -+15V lines will be drained by the voltage regulators. 

10 I would recommend a variac for initial testing it allows you to bring voltages up slowly and make sure that voltages are going up in symmetry (-+400V, -+15V) and becoming stable.

11. If the outputs look good with no amp boards attached, connect one board and repeat the tests. Better to put in channel in danger than both... especially if the amp boards have not been tested.

12. if test with the other amp board only. You don’t want to blame the psu if one amp board only is miss behaving...

13. test with both amp boards. Remember if the -400V line goes down in voltage significantly only with 2 amp boards attached and is fine with one you probably have a current limit problem and did not implement item 2 here!

14 don’t plug in headphones unless 1. you have a spare pair you don’t mind frying. 2. you have tested voltages, dc offsets are nulled and you are happy. ideally look at the outputs on a scope and put some sine waves in....

15 Before you plug in anything visually inspect for solder bridges... I had a partial bridge it only started conducting when the input AC to the psu went above about 26VAC... thank you variac...

16 use probes with insulation, there is lots of high voltages don’t short out things with you probes....

17 Before you power up anything double check the wiring the - and + on the silkscreen are quite small and you dont want +400V going to a place expecting -400V....

18 temperatures are low, with the psu attached at a 200mm by 80mm heatsink with 40mm fins, (both amp boards running constant current 20mA and -+400V  B-+), the centre of the case of the +400V side transistors are about 40C, the -400V transistors are around 3C higher at around 43C. The cases on the C2M1000170D transistors take some time to become as hot as the mounting screws. The 10M90S cases reach the mounting screw temperatures far faster.

19 I know the board has been made as small as possible and around the screw terminals its rather crowded. But it would be nice if there was sepertate screw terminals for the -+400V and -+15V for each channel, this would allow for the use of thicker wires and reduce the possibility of a wire comming out. (I have already had the situation where I though both wires where screwed in tightly to a single terminal and then one came out)

Hope this is useful






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Blue hawaii build notes based on kgbhver6sbipolarinc.

The amp board is fairly easy to build, but I do have a few observations

1. EITHER populate the LSK389 6 pin dual transistor OR the two single transistors each side NOT both

EITHER populate the STN9360 smd transistors OR the KSA1156 just below them NOT both

important and high voltage tracks run close to the screw holes for attaching the heatsink L brackets to the board on the top side of the pcb. I would be very wary about placing the L bracket on this side, if the solder mask is rubbed there will be a short to the L bracket which is probably electrically connected to the rest of the case and the case is probably connected to earth (certainly in countries with 3 pin mains leads) and that’s going to be bad....

2. the tube sockets and trim pots go on the other side of the pcb to the rest of the components. If you want you can also put the leds on the top side so you can see what is going on. The 3 leds will give you an indirect indication of the status of the board. All 3 leds should be lit for normal operation. The led by itself gives an indication of the -400V line, the two leds closer together indirectly show the state of the +-15VDc lines. There is no led for the +400V line.

3. to set the constant current to 20mA you need to measure 1V DC across the 50ohm resistor near the trimpot (one for each valve). Since the trim pot is on the top side of the pcb it makes sense to put the 50ohm resistor on the top side two. I raised the resistor off the circuit board so I could easily clip insulated multimeter probes to the leads.

4. I found mounting the screw terminals to the underside was a pain in the ****. it may look neater BUT to screw the terminals you have to get to the underside of the board. BUT the pcb is mounted to an L bracket mounted to a large heatsink. So, you either have to flip the entire thing over.... hope you have long enough wires to allow this OR put the entire thing on a desk and stand on your head and screw upwards from below.... I am sorely tempted to desolder the screw terminals and mount them on the top of the pcb.

5. if you are going to have a single ended input to the amp e.g. RCA/phono then the -input should be connected to the ground for minimal hum.

6. when you are doing the inter board wiring for the first time make sure the inputs are shorted to ground. I got some instability issues because my input wiring was too close to either the stax output socket wiring or the main transformer and had nothing connected to it and was not shorted to ground.

7 when you build the amps boards set all the trim pots for halfway and verify with a multimeter in ohms mode. This will save you from having a trimpot at one extreme of its travel and result in LARGE DC offsets or high constant current pull....

8. if you have a scope or two multimeters it’s much easier to set up the amp because changing the DC offset also makes the balance change and vice versa. With a 2-channel scope or 2 meters its far easier to chase the correct spot. Adjust the two trim pots near the 50ohm resistors have been adjusted for 1V across the resistor i.e. 20mA current, first. Next you can adjust the dc offset and balance between the valves, the audio inputs should be shorted to ground and no headphones attached for all setup. If you are using a scope make sure it’s set to DC coupling... AC coupling will ignore any DC offset and its DC offset we are trying to null out. Also, if you have a scope do no connect the ground terminals of the probes to anything only the centre pin of the probes is needed. (almost all scopes internally are grounded via the main input) almost all multimeters are NOT and require the ground lead connecting to the amp board or psu ground.

9. Im my experience if you are building a single box amp, even if the transformer has a magnetic shield foil, putting the audio input wires anywhere near the transformer will result in hummmmmmm..... the magnetic field is STRONG with this one...

10 The hottest transistors on the blue hawaii are the FQPF8N80Cs, measuring the mounting screw of the transistor - (which seems to be the hottest part I can find) I get a stable 65C after multiple hours of use, this is using arctic ceramique thermal paste, aluminium L bracket 200mm by 80mm heatsink with 40mm fins and aluminium oxide insulation pads.... 20mA constant current and +-400VDC B-+

11. double check which trimpot you are adjusting. I have adjusted the constant current trimpots by accident when trying to do DC offset and balance multiple times....

12 some labelling of the trimpots to say what does what on the silkscreen would be nice...

13 labelling the screw terminals on the top side of the board would be nice for checking wiring after the boards are in place.

I hope this is useful



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  • 2 weeks later...

Im using LSK389A in my blue hawaii, with a 10K log pot I get good control over the volume and "normal" listening around 12 oclock. The source to the hawaii outputs 2.2V full scale....

I believe the LSK389B would also be fine, especially if you have a source with lower output or you like to listen at higher volumes or prefer to not have the volume knob around so far...


Edited by jamesmking
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  • 3 months later...
  • 1 month later...
19 hours ago, mikeymad said:

I can never afford (justify) them - but I still want to listen to them, hoping my blackburn xf2s last a long time. 

There is an alternative way of looking at this - think of purchase like this as an insurance/investment if the price is within reason.

Given the scarce of these tubes, it's not unreasonable to think that down the road one should be able to sell them for the same if not more dollar amount if one decides the tubes do not justify their cost. At least that's what I try to tell myself from time to time 😉

The challenge though, is establishing what is a "reasonable cost". 

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  • 10 months later...

Hi guys, 

any experience with combinations about 10k/50k volume pots and the different LSK versions? 

I saw above James using 10k with the LSK389A, which would have been my favourite as well. 

But... It seems I can only find the Alps RK50 in its 50k version and am not sure whether I should order the LSK389A or the LSK389B for my Blue Hawaii. What would be your recommendations? I would be using an XLR source, mostly a DAC like the Mytek Brooklin, Squeezebox Transporter or Topping D90 MQA.

Thanks very much! 

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