EHX - Riddle QBalls VCF

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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uncleboko
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Post by uncleboko »

Yes I did, but I think there is some serious circuitry in there for the detection and AD generation to warrant the size of box, although the filter could be the same.

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Post by uncleboko »

uncleboko wrote:Yes I did, but I think there is some serious circuitry in there for the detection and AD generation to warrant the size of box, although the filter could be the same.
Bugger my iphone, bloody awful for posting here.

The whole point is that whereas the various qtrons satisfy those who merely need quacking duck noises, the Riddle has a seriously smooth long sweep which must take the circuitry into a different ball park altogether.

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Post by Ice-9 »

uncleboko wrote:
uncleboko wrote:Yes I did, but I think there is some serious circuitry in there for the detection and AD generation to warrant the size of box, although the filter could be the same.
Bugger my iphone, bloody awful for posting here.

The whole point is that whereas the various qtrons satisfy those who merely need quacking duck noises, the Riddle has a seriously smooth long sweep which must take the circuitry into a different ball park altogether.
Yeah, I'm wrong in my initial assumption after spotting the 'qtron' within the word puzzle, this thing is definitely something more :oops:
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?

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Post by pervyinthepark »

Just thought I'd revive this. Gutshots anyone? I might be able to get some from a friend

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uncleboko
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Post by uncleboko »

A pedal tech told me its almost entirely opamps, with a quad comparator thrown in for good measure!!!

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Post by uncleboko »

uncleboko wrote:A pedal tech told me its almost entirely opamps, with a quad comparator thrown in for good measure!!!
With a plethora of resistors, caps, dual diodes and a vactrol. More than that I cannot say having lost touch with this guy.

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Post by howmuch »

Wow! Nearly 9 years since this thread started, and no-one on here has bought one?

Well I just bought one, because at less than £70 brand new at the moment in the UK, how could I resist?
Not really worth DIY-ing at that price.

Looking at the Riddle compared to the Q-Tron+, there's just no competition.
For flexibility, The Riddle beats the Q-Tron+ hands down, and luckily it's half the price!
I guess using a "Riddle" just doesn't sound as "cool" as using a "Q-Tron", so the Q-Tron+ can command the higher price.

I haven't heard a Q-Tron+ or Mu-Tron in the flesh, but this Riddle sounds great.
As well as the usual auto-wah type quack that gets demoed a lot, it does very nice synth-like down sweeps. Highy recommended.

The Riddle is using the same two NSL-32 optocouplers as the Q-Tron/Q-Tron+ shown in the pictures here (viewtopic.php?p=254760#p254760)


Main components of interest:
( [] = PCB legend )

LDR1, LDR2 = NSL-32, marked "NSL-32-034A 1333", "NSL 7053" on end [OPTO/BF] - Optocoupler
U1, U2, U3, U4, U6, U7 = JRC 4558 [MC4558CD]
U5 = ST 064C [TL064CD]
U8, U9, U10 = ST 062C [TL062CD]
U11 = LM2901DG [LM2901]
U13 = NXP HEF4066BT [CD4066]
U15 = LBXB N212 348 [LT3487]

Trim 1 Pot = 10k set at 03:30
Trim 2 / Distortion Pot = 10k set at 11:30

Pots
Blend = B10k
Mode = Rotary-2P4T
Attack = A250k
Decay = A250k
Start = B10k
Stop = B10k
Q = A250k
Sensitivity = A250k

Voltages
Mains Adapter, no-load = 10.0V
Riddle, 9V = 9.6V
Riddle, 15V = 15.16V
Riddle, -15V = -15.05V

Apparently, I read that all EHX products with Exp. Pedal inputs expect 10k.


Anyway, here's some gutshots...
If anyone wants specific close-ups, I'll see what I can do.
P1070106.JPG
P1070122.JPG
P1070134.JPG
P1070186.JPG
P1070135.JPG
P1070133.JPG
P1070132.JPG
P1070347.JPG
P1070187.JPG
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Post by Scruffie »

So the Start/Stop/Attack/Decay 'core' uncleboko was after must be formed with the 4066 & Quad Comparator.

Interesting rail splitter chip too.

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Post by uncleboko »

I'm guessing that the 4558s are used in the input/VCF/output path, and the TLO62s & 64, LM2901 & 4066 form the control circuitry.

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Post by uncleboko »

The LT3487 looks like an unusual beast!

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Post by uncleboko »

I've been watching a couple of Riddle demo videos, I don't hear any of the usual hideous junior micro box quackery, some serious thought went into its design. What can LM2901 do that LM339 can't?

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Post by Scruffie »

uncleboko wrote: 28 Jul 2020, 09:32 What can LM2901 do that LM339 can't?
https://www.ti.com/lit/ds/symlink/lm290 ... 252FLM2901

Still operate at wider temperature extremes.

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Post by uncleboko »

Still DIP for LM2901 - excellent!!

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Post by howmuch »

I can confirm that the Donner Viper works to control the EHX Riddle using a TRS(stereo) lead into the "Exp. Pedal" input.
The output looks like a 10k linear pot.
(Donner 2 in 1 Viper Mini Passive Volume Expression Guitar Effect Pedal)
R.I.P. Burke Shelley, from one of my favourite (and much underrated) bands - Budgie
Their songs have been covered by Van Halen, Iron Maiden, Soundgarden, Metallica and more.
If you don't know how HEAVY this band was in the 70s, check Breadfan out.

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