He-69 build/support thread. PCB's/kits-available!

[tomheavybeats]

This project was made by Igor 10 years ago. If you see there's not much activity after 2014.
Igor left this forum in 2013 and unfortunately the last news we had was that he passed away.

There's other Helios projects going on at the moment with "Mic Pre+ EQ" for the 500 series format, much more flexible than this one because this was just the EQ section. People moved on from this the the newer projects.

I wish you all the best for your build, and you should read the info that is already in this thread to help you out but don't expect much activity in this thread

Oh no, really sad news and yes sorry that was my first post here so I’m still getting up to speed.
Many thanks for the heads up, looking forward to this build and hope there’s enough info here to help and will check out the pre+EQ as a next build maybe. Cheers!

 

[Whoops]

hope there’s enough info here to help and will check out the pre+EQ as a next build maybe. Cheers!

If you have all the docs, plus this thread you will be able to build them with no problems

As far as Helios projects with Mic Pre+EQ I think theres at least 2 different ones.

A lof ot info and threads on Helios here in the forum in the last 3 years, just do some deep searches

 

[tomheavybeats]

I have read through this entire thread and now I’m really worried about building these. I bought 2 sets of PCBs and front panels from frontpanels.de, in and out Lundahl trafos and grayhill switches. Have spent a lot but I’m wondering whether to cut my losses as there really aren’t many successful builds of this and I’m still confused as to the relay issue (some say 5v ones don’t work and need 12v). I would like to know if there’s anyone here with successful build please who can answer the relay question and link to one that works?  Completed builds on this thread seem to teem with issues. Thanks!

 

[Rogy]

Hi Tom,

I finished assembly of four HE69's just weeks ago.

Everything works as expected and the sound is really nice.

There were a couple of minor changes to get the Carnhill inductors correctly connected, but other than that the assembly was a breeze.

I'll go thru my order list and let you know which relays I used.

Best regards,

Rogy

 

[tomheavybeats]

Hey Rogy, thats great to hear and would really appreciate it, thank you. You've just inspired me to continue with this project too
If you have a mouser cart or similar and don't mind sharing that would be great, I have almost completed mine but would love to double check it against someone else's. I have all the build docs and in Igor's pics he uses a lot of polystyrene caps, did you go this route too as BOM just says to use film caps?

Thanks for the heads up on the inductor, when i get to that stage I will see if I have trouble too and may message you if ok.

Cheers
Tom

 

[Bobby Baird]

Up and running. I need some standoffs.

 

[Whoops]

I finished assembly of four HE69's just weeks ago.

Congrats, please share with us pictures of your units

 

[Bobby Baird]

Hi Tom,

I finished assembly of four HE69's just weeks ago.

Everything works as expected and the sound is really nice.

There were a couple of minor changes to get the Carnhill inductors correctly connected, but other than that the assembly was a breeze.

I'll go thru my order list and let you know which relays I used.

Best regards,

Rogy

Hi Rogy, everything looks good on my pair except for the mid band. It seems the 9048 inductor is not pin out correct for my 1.4version boards. I'm assuming you had to flip the inductor and hard wire to the correct hole marked 200mH, & 700mH. If so would it be possible to show us how this was done?

 

[Rogy]

Hi Bobby,
Congratz! Looking good!

Hi All,
The relays I used are the following:
Panasonic TX2 12V, Farnell order code 1200952
Rrel = 107R; I used 100R.

As for the other 'TBD' values: Those are really dependent of the DOA used and the gain structure chosen.
I decided to use the LL1524 in 1:1 config (requires some PCB trace mods), thus R12 and R15 need a ratio of 50:5.1, and I used PPA992 DOA's.

 

[Rogy]

Hi Rogy, everything looks good on my pair except for the mid band. It seems the 9048 inductor is not pin out correct for my 1.4version boards. I'm assuming you had to flip the inductor and hard wire to the correct hole marked 200mH, & 700mH. If so would it be possible to show us how this was done?

In attach are two pics of the orientation of the inductors;

I did some trace changes to the big inductor for the lows, see details in post below.

 

[Rogy]

PCB changes to make the Carnhill inductors work:

VTB9043 (the larger one for the low freq band): I cut a trace below the inductor (PCB top/component side), and jumpered two pads on the PCB bottom/solder side.

VTB9048 (the smaller one for the mid band): No changes needed.

See pics attached; changes indicated in red.

Please ignore the black wire; I separated the two PCB's too close to the edge connector and accidentally interrupted a trace...

Good luck!

Rogy

 

[Rogy]

Here are some closeup pics of the low band gain pot:

 

[Bobby Baird]

PCB changes to make the Carnhill inductors work:

VTB9043 (the larger one for the low freq band): I cut a trace below the inductor (PCB top/component side), and jumpered two pads on the PCB bottom/solder side.

VTB9048 (the smaller one for the mid band): I jumpered two pads on the PCB top/component side.

See pics attached; changes indicated in red.

Please ignore the black wire; I separated the two PCB's too close to the edge connector and accidentally interrupted a trace...

Good luck!

Rogy

Thanks, Rogy for the detailed inductor mods. Can you explain what was wrong with the 9043 original traces? I didn't notice any odd behavior. What does the mod achieve? Other than that thank you for sharing your knowledge!

 

[Rogy]

Thanks, Rogy for the detailed inductor mods. Can you explain what was wrong with the 9043 original traces? I didn't notice any odd behavior. What does the mod achieve? Other than that thank you for sharing your knowledge!

Hi Bobby,

From memory, in the original scenario the measured EQ curves were all too high on the frequency scale. I measured the inductor and it was wired for 7H (tap D) instead of 10H (tap E).

Please measure your EQ-curves to verify, or check the inductance if your multimeter has an inductance measurement function.

Best regards,
Rogy

 

[Bobby Baird]

Hi Bobby,

From memory, in the original scenario the measured EQ curves were all too high on the frequency scale. I measured the inductor and it was wired for 7H (tap D) instead of 10H (tap E).

Please measure your EQ-curves to verify, or check the inductance if your multimeter has an inductance measurement function.

Best regards,
Rogy

I'm assuming this mod shifts the curves a little lower? As is on mine viewing on span with pink noise the curves look to be off slightly higher then the
60,80,120,240,400 would suggest. More like 80,100,150,300,420 as is.

 

[Rogy]

I'm assuming this mod shifts the curves a little lower? As is on mine viewing on span with pink noise the curves look to be off slightly higher then the
60,80,120,240,400 would suggest. More like 80,100,150,300,420 as is.

Exactly! Mine were off even more.
I'll try to dig up the final curves and post them here for reference.

 

[Rogy]

Attached some graphs of the different Low Band settings at their extremes.

 

[Bobby Baird]

Flipped the 9048 with the retainer clips and soldered resistor legs to the correct inductor taps as idicated on the back of the pcb to the correct taps on the inductor. Mid band is working now.

 

[Bobby Baird]

I have a 1.6 db of gain drop when engaged. I suppose i should drop my R12/R15. Probable end up using sockets on those.

 

[Bobby Baird]

Bias pot for R12 feedback resistor to set unity gain.