Roland Jet Phaser!

[danfrank]

Ok, I'm not joking this time, this needs to be done! I'm sure JimiLee will back me up on this... Warm Audio just released an authentic remake so unobtanium parts is no longer an excuse!
This would be a great project... Able to fit in a 1590BB would make it double nice.
Any takers?
Lol!

[Betty Wont]

I'm in!!

[jimilee]

Daaaamn, sounds awesome.


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[aion]

I've got one in the works. It'll be 1790NS/1590XX though, 1590BB is a little too masochistic and would be a much more difficult build.

[danfrank]

Nice, Great to hear!
Do you have an approximate ETA?
Thanks

[aion]

Maybe spring or summer... it's about half designed, but I'm working through options for offering matched JFETs along with it and that's the main delay. Don't want to put it out there if it's near impossible to actually build!

[madbean]

That is killer. Looking forward to building one.

[danfrank]

Maybe spring or summer... it's about half designed, but I'm working through options for offering matched JFETs along with it and that's the main delay. Don't want to put it out there if it's near impossible to actually build!

Can you give info as to what FETs work well with this? Will your standard matched phaser FETs work or do they need to be a special type? I know there's 8 of them doing the deed.... The original 2SK30s haven't been made in a long time, audiophiles liked using them before they got scarce.

[Thewintersoldier]

this is gonna be a fun build, can't wait Kevin!

[aion]

Maybe spring or summer... it's about half designed, but I'm working through options for offering matched JFETs along with it and that's the main delay. Don't want to put it out there if it's near impossible to actually build!

Can you give info as to what FETs work well with this? Will your standard matched phaser FETs work or do they need to be a special type? I know there's 8 of them doing the deed.... The original 2SK30s haven't been made in a long time, audiophiles liked using them before they got scarce.

That's part of the research I still need to do. Lots of people have tried and failed to make a DIY version, so I think the FETs are important and need to meet certain specs that are different than the standard Phase 90 matched set. They seem to be lower in Vgs(10k) in general but I don't know if that's the full story.

I have two original units on the bench for dissecting, so I'm confident I'll be able to crack it, but just not sure yet what I'll find out.

[aion]

Went on a bit of a tear the past few days and came out the other side with this.

I ended up tricking it out pretty thoroughly, which was fun. The rotary switch on the original is nice from an aesthetic perspective, preserving the simple control layout, but it hides some parameters such as jet tone and phaser depth/intensity that are set with fixed resistors and switches instead of knobs.

So we end up with these extra features -

• Jet (the distortion circuit before the phaser) is independently footswitchable
• Full tone control added to Jet mode (the original just has 2 modes, full CW for treble or full CCW for bass on a Big Muff tone stack)
• Distortion can be dialed back (full-up is equivalent to stock) - which should allow for some semi-clean boost to fix volume issues, as well as less fuzzy drive tones
• Depth control added (original rotary control just had two depth presets)
• Fast speed added (on the original, Fast mode is a preset speed and only Slow mode is adjustable)
• Toggle switch for phase stages (4/6/8, with 8 being the stock mode)
• Input buffer added from 1976 revision (most DIY attempts have not included this buffer, which Roland added less than a year after production started in 1975 due to reported volume issues) - the buffer always comes before the effect, but there's an internal slide switch allowing bypass mode to be either true bypass or buffered
• Charge pump inverter for +/-9V (the original required 2 batteries and had no external power jack)

So the end result is that it's still electrically 100% identical to the original Jet Phaser, but a lot more flexible.

I'm only just sending it off to prototyping today, so it'll be several weeks/months before it sees the light of day (and that's assuming it works... lol) - but just to prime any appetites, a significant milestone has been hit

Time to dust off those JFET matching rigs...

[Betty Wont]

oh my......!!!! fantastic!!! best of luck on the proto, I'll be watching this one.

[gordo]

That is sick.  I must admit that my recollection of the original was that it was a one trick pony (although a fun one).  This looks like it will be just short of completely insane.  Really looking forward to it.

[jimilee]

Jeeeeesus; I'm all in.


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[danfrank]

Thanks for the update and (2x) thanks for working on this! I'm really looking forward to this project. I love the name!


BTW, I just finished the 2 Blueshift boards and I plan to use them in a PA with 4 (QUAD!) Gromes G-101 100 watt tube amps for super-wide stereo. I was wondering how to make a 2 channel system into 4 and the 2 Blueshifts I have will work perfectly.
Thanks again...