Polytone in a Pedal

**lawson-stone** · 01-20-2017, 10:00 AM

Originally Posted by add4

Hey guys,

I'm also thinking of doing a more complete version of this:
would you give me some ideas of things you'd be interested in?

so far the possibilities are (i'll most probably not put all of this in a pedal .. there will be choices..)

- Cab sim (analog or digital with USB loading?) on a dedicated output
- reverb
- limiter to add a slight 'tube like' compression
- OD channel?
- don't make me put a delay in there too

other ideas?

So are you thinking instead of the form-factor being a pedal, it would be more like a micro-head? That could still to me at least be very attractive. I can do without the OD and limiter, but an auxiliary input and XLR out would be welcome to me. Not deal breakers if they aren't there, but something that would add to the appeal.

**add4** · 01-20-2017, 05:08 PM

Ok guys i am currently testing out some components values for the low end control switch and i have to say this .. i was a bit sceptical at first ... but now that i'm trying it out i can't imagine not putting it in the pedal it really helps to keep things fat, but much more defined and clear, ... thanks to Jorge for the suggestion !

all in all i think it sounds great as it is .. tonight is about defining components values for that switch and start to redo all the layout.

also after tinkering with the gain pot, i will leave the light crunch thing out of the box, it's a los of headroom and doesn't sound as good as without the crunch..
then the gain knob doesnt do anything worth keeping it into the pedal, i'm removing it

**Cunamara** · 01-20-2017, 07:32 PM

As for cab sim, etc., why not sim the Polytone MB II? That would move it beyond a Polytone-ish preamp to a Polytone-in-a-box (Polyclone? Minitone? Pedaltone? Pocket Brute? Et Tu Brute? Zygote Brute? Zygotone? Cuppa Joe? [in honor of Joe Pass inspiring the Mini Brute]).

For me, the use would be to run direct to a PA or to into my AI Clarus 2r- which is practically a PA- to add warmth and color for archtop jazz guitar, so XLR would be nice. Not a deal breaker. I haven't heard the low cut filter but having that might help with feedback with archtops, since that tends to be caused by bass frequencies. Built in reverb would be nice but tastes vary so widely on that sound (spring, plate, hall, room, etc.). Might be better to leave it out and let people use whatever reverb they have already.

**sgosnell** · 01-20-2017, 09:23 PM

I agree about the reverb. I already have a reverb pedal, which I can use to get almost any reverb type I want, and I probably wouldn't use a built-in reverb at all. I don't use the reverb on my amps.

**add4** · 01-22-2017, 11:18 AM

Ok guys, a quick update of the last few days ... basically, life happened

Still i made some tests with the limiter circuit i had in mind, and while i think it sounds great and can really make the sound more 'studio like', evening it out, but avoiding the 'pump' effect of most compressors .. so i'm happy about it, but ... i won't put in in there because it's not the point of this project and i know i have a tendancy to make everything overcomplicated. I would just like to keep that the basic polytone amp, at first anyway.

2 things i'd still want to try:
- make the bass cut control a pot instead of a switch.. i have several ideas to implement this and will try them asap
- remove the charge pump inside it, so make it a 0/+9v pedal instead of a -9V/+9V. If more headroom is needed you could still plug a 0/18v power supply and have the same headroom.

So .. would you find these 2 things useful, or would you prefer the low cut to be switchable with 2 low cut values only?

Once it's fixed, i can redesing the box, adapt the circuit, create the PCB, produce it, ...
but at least the choices would be done

so in summary we would have

polytone preamp with
- bass/mids/treble tone stack
- volume
- voice switch with the dark/normal/bright settings
- bass cut control, either a switch or a pot
- internal charge pump to get 18v headroom (centered on 0) (to keep?)
- burr brown OPA2134 operational amplifier. because, as Jorge stated.. it's noticeably better than anything else
- mono in
- mono out
- hammond enclosure with UV printed labels so basically professional level finish
- i plan to use 13mm black metal knobs on this
- highest available quality in/out jacks, caps, ...

Your thoughts?

**add4** · 01-22-2017, 11:26 AM

Just for fun. Here is a picture of the preamp with the compressor on my testing rig. Pretty clear right ?

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**add4** · 01-23-2017, 06:24 PM

Getting closer. Still have to track the inevitable mistakes, correct some traces, dimension errors and I could produce those.

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**add4** · 01-23-2017, 06:25 PM

Probable final layout:

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**Little Jay** · 01-24-2017, 02:53 AM

Looking good!

You are going to be busy the coming months.....

**add4** · 01-24-2017, 05:49 AM

THanks for the kind words guys .. unfortunately, i'll have to redo most of the circuit as i made a mistake in the measurement on the DC jack

if i continue like this i won't be able to fit the circuit plate and the DC jack into the enclosure ..

So i'll probably invert the lines of the controls : Vol, low end control and voice on top, EQ on the bottom. easy work for the box design, but i'll have to start the pcb from the very beggining another time

While i'm at it i'll probably throw another couple of hours into testing the pot for the low end control since i don't want to provide two choices that you wouldn't like.. i'd feel safer with a pot, and i know how to do it.
So, it's one step forward, two steps backwards, but i'm ok with it since it's the only way i know to make things better.

I can't wait to have a completed one to show it to you guys

**add4** · 01-24-2017, 05:52 AM

Originally Posted by Little Jay

Looking good!

You are going to be busy the coming months.....

you have no idea how much i hope that your prediction gets real!

i'm currently spending most of my free time (evenings, morning, lunch at work) working on this.. i don't even play much anymore to go forward with this while i'm into this enthusiastic energy zone.

I'm also learning a lot with this because i'm also trying to design my pcbs in a much better way to minimise external wiring.

Anyway thanks for your support guys

**lawson-stone** · 01-24-2017, 09:46 AM

Seriously I can guarantee at lest one sale! I'm very excited about this. I am an amateur, and very often I play in situations where I'm lecturing or speaking and so I've packed along my guitar, but no amp, just to practice. Then somebody says "Oh that's nice, why don't you play a piece for the program at our closing dinner?" and suddenly I'm going to play in front of a large crowd; one or two tunes, plugging direct into the PA system. Having a Polytone pre-amp in my guitar case will make a huge difference in that kind of situation, which happens quite often for me.

I'm also sure that Joe Pass would have been among your first purchasers. He traveled without an amp and liked to go through the house PA, and having the Polytone front end would have been perfect.

**Little Jay** · 01-25-2017, 11:55 AM

Ok, I convinced myself I definitely need this pedal. Can we place orders already? ;-)

**add4** · 01-25-2017, 12:01 PM

Hey guys. I just received some pcbs for my booster. so, NOT the polytone preamp but I thought I'd share a pic so you have an idea of the quality of the pcbs. And I guess it's also interesting for you to see the inner parts of the pedals for once.
The multitone board will be similar to this in quality.

About the pedal I have tried several things for the low end control. Went back to a switch with better results than with a pot. And it can be turned off for "pure polytone" tone. I'll still try a solution with a pot tonight. Maybe with a detent that turns it off?
But I'll probably stick to a switch with 3 positions and start designing the pcbs this week.

Thanks for following this project

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**Little Jay** · 01-25-2017, 02:18 PM

The switch is more true to the Polytone design and might be a better solution just because of the psychological effect (the auto-suggestion of having a Polytone in a pedal) of that..... ;-)

**mezzo** · 01-25-2017, 07:40 PM

XLR output and reverb please! For those who are lazy like me... ;p

**Frank67** · 01-26-2017, 02:26 AM

Let us know when we can order. I am planning to put together an elaborate "direct to the PA" pedalboard sometime this year and this could be my jazzy "channel" - nice!

**add4** · 01-27-2017, 07:18 AM

Hello guys, Before moving to the ordering part, i think we need to talk about price.. i have postponed this because i hate that part of the discussion. but if i'm going to spend all my evenings working to design the pedals,build and debug them and invest some money, i would like to know how much it's worth to you

So what i propose is this: we have a small number of people interested here, and i think it could work to know what it would be worth to you and work from there to find a fair price for you guys and for me. So i made a google survey and if you could just fill it up i'd have an idea of how much eveyrone think this pedal would be worth and i'll try to make a proposition of a price that makes it worth for me to spend all my free time doing this, and ok for you. Please keep in mind that the pedals you usually buy are made in a factory, with machines, and the prices for every component in the pedal is drastically lower than what i'll pay to build yours (i pay taxes on it, plus i buy low volumes of components). and also that desiging that stuff is fun, but also takes time and is an investment (the last pcbs i received , i think you have a small idea with the things i post (i'm already at the 4th version of the printed circuit board for example... )

If we can reach a minimum price for me, i'm also willing to make a reduction for those who would be interested by the first batch. so I propose to talk about the price for a first batch and then once we agree on something, just PM me if you are interested in one and i'll start a list, first one to suscribe, first one to receive the pedal. Does that sound right to you? So here is the survey Multitone pedal price survey please also keep in mind that sending things can be expensive here (i looked at the belgian post and they seem to ask 32 euros to send a package between 350gr to 1kilogram, so i might have to find better solutions, if they exist) .. and there might be taxes also.. (actually one of the reasons i start building again is because of the frustration of the too high prices of the high end pedals from the US here in europe) thanks for your help and interest

**add4** · 01-28-2017, 01:27 AM

Oops. The web version of the forum seems to screw up most of my attachments somehow.

So the question was: who wants to play?

.

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**add4** · 01-28-2017, 04:26 AM

Well, this time, the process was actually much easier than it was for the earlier versions.. maybe spending all my evenings on this pcb design program actually helps me getting better at it?

here is the sixth version of the pcb

I HOPE that this time i did not forget anything ...

I still have to go through the errors detection process, making it cleaner, check if it would fit the box correctly for the 3983892th time, ...

**lawson-stone** · 01-28-2017, 10:05 AM

I'm in. Whatever options you include or don't include, I think if the basic Polytone pre-amp controls are there, then I want one.

**add4** · 01-28-2017, 10:09 AM

Originally Posted by lawson-stone

I'm in. Whatever options you include or don't include, I think if the basic Polytone pre-amp controls are there, then I want one.

They definitely will be there.
I think the last pcb version is a probably winner. It tested ok with all the safety checks, it's logical and it should fit the box. I'll most probably send it to factory tomorrow. I'll sleep on it to have a fresh look on it tomorrow just to be sure.

Keeping you updated as always

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**add4** · 01-28-2017, 05:23 PM

Ok guys. Pcb sent to production. That will probably take 2 or 3 weeks to get them. Then I'll see if I created an expensive clipboard or a preamp

It's easy to make mistakes.

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**Frank67** · 02-01-2017, 03:28 AM

Nice sound and really nice playing Jorge. Well done! Do you use only the effects on the amplifier because you do not like the amp sims?

**jorgemg1984** · 02-01-2017, 07:53 AM

Hey Frank, thanks for your words!

Well, I really didn't like the amp sims... I only tried the Twin Reverb, because it's what I would have wanted to use and, to my ears, it sounds nothing like a Twin. I had a bean POD HD once and found the exact same thing - too much bass, too much treble, too much compression... sounds kind of like the amp is running on 10, no sweetness at all. And the tone controls act very weirdly, with drastic changes after minimal turns. Just to clarify, I played a true blackface Vibrolux quite a few times and I know how the real thing sounds - the Barber Barb EQ, a solid state pedal, perfectly mimics the amp's sound and the tone stack, the knobs behave perfectly.

Anyway, when I got the Amplifire I was already sure I wouldn't like the modelling - I wanted good fx, IR loading and stereo jack and xlr outs. I also got it used at an excellent price... and the fx surprised me, love the eqs and I can have stereo ping pong delay, stereo reverb, stereo tremolo and an excellent compressor. All of them have lots of parameters and you can tweak what you want. The reverb (spring2) and the compressor are particularly good - the best I have ever tried (keep in mind I never had a Kemper or a Fractal but have had or tried pedals from Strymon, Eventide, TC, etc...). The delay is also cool because you can have 4 different ping delays at the same time, sounds kinda crazy and cool.

So I just use a preamp pedal (Polyclone, Barb EQ, Ethos, the future Mambo Fender) and the Amplifire, it's still a very small and cheap setup that sounds quite good, never liked my sound this much.