HE-569 pre/eq 500 series

[okgb]

I'm late coming to the party! are there any more kits available ?

Some companies use a switch to reverse the transformers for line input, that maybe an option?

Anyone have a schematic of the transformer switching ? [ reversing the i/o ] I think hairball uses it, not sure who else!

 

[thewotan]

This looks so promising! How is it coming along?

 

[pahstah]

I should receive the new pcbs in the next days, fingers crossed

 

[iprovlek]

Hi Paolo!

Which transformer could be use in new pcb!?

 

[thewotan]

I should receive the new pcbs in the next days, fingers crossed

That's great! Are those just for testing or will you have some for selling?


And many thanks for this project!

 

[pahstah]

The transformer will be Cyril Jones Lustraphone. I hope it will work so I can offer pcbs.

 

[mylesgm]

I'd be interested in couple, will you post a white market link?

 

[Whoops]

Hi Pahstah,
how did your new PCB's turned out?

Any developments on this project?

Thank you so much

 

[rockinrob86]

I’d love an update too, hopefully progress is occurring! This is a great project

 

[iprovlek]

I tried contact Paolo a few time and nothing! It is like Paolo disappeared....I bought his Helios pre/eq but didn't found time

to build it!

 

[vitopower]

Does anyone know which of the resistors on the BOM sheets are the 6 values for the 22113 fb resistors? The main board schematic shows these as between 820R and 22k, but the gain resistors BOM don't show 820R but show extra, non-original resistors outside of this range.

 

[oldskool1]

I actually joined GroupDIY because of this project. I would visit every day to see the progress, getting more and more excited about building four of these preamps to get closer to the sound of the album that blew my mind when it came out, Led Zeppelin IV. It's so sad to see such a beautifully laid out board and panel just fade away.... Hopefully Pahstah will either offer these commercially (hopefully for a little less than the H2 guys charge ($2000)) or finish the kit and offer it in the White or Black market. I'm still hopeful!

 

[Whoops]

well,
it's a shame if this project doesn't see the light of the day, but there's also more Helios projects going on in this forum just search for it

 

[Cyril Jones]

I have 19 of my Lustraphone transformers in stock having just completed a batch. I also designed a small mic amp with the voltage follower attached. the whole board is the width of the 8 pin socket, the board having gold plated figures as per Helios designs.
Cyril

 

[Whoops]

I have 19 of my Lustraphone transformers in stock having just completed a batch. I also designed a small mic amp with the voltage follower attached. the whole board is the width of the 8 pin socket, the board having gold plated figures as per Helios designs.
Cyril

Nice one Cyril,
Can you please post photos of your PCB?

thank you so much

 

[duantro]

Yeah was pretty excited about this project. Too bad it’s seemed to fizzle out

 

[Cyril Jones]

Hello Whoops. Here is the Helios regulate mic amp and voltage follower on a small pcb. VF is small section divided by the solid line.

 

[Cyril Jones]

Hi, note should read regular mic. amp Cyril

 

[Whoops]

Hello Whoops. Here is the Helios regulate mic amp and voltage follower on a small pcb. VF is small section divided by the solid line.

Very nice Cyril,
it's really small the pcb.

What is the Voltage Follower circuit? What is it for?

Thanks

 

[Cyril Jones]

Very nice Cyril,
it's really small the pcb.

What is the Voltage Follower circuit? What is it for?

Thanks

Early Helios channels used the 2180 pre-amp,, followed by the switched passive bass filter which requires a high impedance follower, the EQ section requires a low impedance drive., the voltage follower provides both. Later modules incorporated the VF on large circuit boards using a 16 way connector. I have reduced to this design and thus lessen the cramped nature of components behind the front panel.
Here is a plea, for those constructing the early modules please use a small relay adjacent to the input transformer to change the microphone phase or move the phase switch to the top of the module. The module could be more stable at high gains if the microphone input cables and switching remain at the top of the channel away from high level signal levels..
Cyril