Hughes & Kettner - Rotosphere  [schematic]

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ssmc
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Post by ssmc »

And i AGAIN found some mistakes. T8, T9, T10 and T11 were not connected as they should be. This is getting more and more irritating :mrgreen: and in a week or so I plan to have this PCB made.

I will keep updating as I find more errors (my God, please no more :blackeye )

BOM stays the same. I also saw that there were ppl who downloaded files.It would be nice to share mistakes if you find them you good ppl :thumbsup

Why am I getting that feeling that I am getting boring? :mrgreen:
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Rotosphere.zip
AGAIN fixed layout
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ssmc
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Post by ssmc »

Hello people, haven't been around for a while. Got some more corrections, and I hope this is it, I'll probably give this PCB to be made today or tomorrow.In case that it is correct, I would need some help with calibrating this thing.Any advices maybe?
Attachments
Rotosphere.zip
Layout. Hopefully final version.
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Karsten21
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Post by Karsten21 »

Hello SSMC,

I just will say: Deeeply bow down about your work on the layout! I´m realy interested if this project will work because the schmatic looks quite complex for an DIY project.
Short question: Do you use any schematic <->layout relation ship in your layout software to ensure not to mix up signals or missing junctions?

Best regards
Karsten

ssmc
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Post by ssmc »

Karsten21 wrote:Hello SSMC,

I just will say: Deeeply bow down about your work on the layout! I´m realy interested if this project will work because the schmatic looks quite complex for an DIY project.
Short question: Do you use any schematic <->layout relation ship in your layout software to ensure not to mix up signals or missing junctions?

Best regards
Karsten
Hi Karsten,

Thanks for the kind words. I hope this will work because I gave this PCB to be built, and people from the company say it will be done in about 7-10 days.Then I will know if layout I did was good.
This layout was drawn without schematic-layout relation in layout software.I am not sure but I think this software is for layout drawing only.Maybe I missed that with schematics relation.
I compared schematics and layout to make sure everything is ok.Maybe there is still some mistake there lurking, I don't know.Guess I'll have to wait for that PCB to be made to find out.

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Post by ssmc »

Hello guys, I made PCB, but you can all guess that it's not working.....at all!
I measured some voltages to check that I didn't fried something, but everything seems ok.
I mean everything is dead!! I suspect I connected it wrong at the very end. Switching that is. Can anybody post the pictures how the switches are connected, or if not can somebody explain how to do it, since there is schematic.

Thank you all who are reading this.

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Post by Fredenando »

Here are a rar file with all that I have, but I think that all are published before... I hope this can help you.

http://www.4shared.com/file/aTHUkUXx/Hu ... phere.html

ssmc
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Post by ssmc »

Here are some pics of finished and partially populated PCB. I actually finished and tested the circuit but my girlfriend went on vacation and took it with her, so I will post pictures of populated PCB later.


Image

Image

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I have some problems to make it work as it should work. Some noise is coming from the oscillators, and I my friend told me the effect is not that strong like with the original rotosphere. Bypass is not working, pedal is always on......

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Post by Herec »

Looks great! I haven't been able to do schematic/board tracing, my computer has been in the gutter, but I'll try to help as best as I can. Any idea of where to start with what's wrong?

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Post by ssmc »

Well I suspect that some of traces are connected, the manufacturer had problems with making PCB because traces are much too close so the errors occurred. I managed to track some of them and separate tracks that shouldn't be connected, but maybe there is error that I didn't noticed (which would explain why bypass won't work). I checked schematics and layout and to me everything seemed fine, but it is possible that there is some mismatch in layout/schematics (although the thing works). I don't know where to look at for that clock bleed that is so huge I think it goes directly into signal path. Maybe it is from MN 3102 chips, and maybe it is from oscillators. Maybe it's MN's rather than oscillators because the sound of that bleed is not in synch with LE diode. Think I'll go to my friend that has o-scope, and is experienced with MN's. Until then I have to learn for exams that are approaching.

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Post by krueppel-keile »

I started to build one of these with the help of ssmc's layout.
I found a few errors, the in/outputs are strange and there was a resistor in the oscillator circuit that was connected wrong.
Lets get that thing to work! Im sure its possible unless some diabolic H&K person put some errors into the schematics deliberately. :twisted: :roll:
maybe ill post some pictures of my progress later.
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rotosphere.zip
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Post by krueppel-keile »

Okay, now for some some shitty webcam pics:

Image
Image
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Image

The PCB was made at home using this tutorial:http://thomaspfeifer.net/direct_toner_pcb.htm
This method is as simple as it gets, and cost me around 10 euros. Since i never tried something like that before, it actually surprised me how well it works.
If you want to try this too, i want to add a thing or two:
If the transfer process didnt go well, and you have disconnected traces but dont want to repeat the whole printing/ironing, you can just repair errors by painting them over with a waterproof marker, like an "edding". Just make sure you paint over multiple times, so the layer gets thick enough to resist the etching. If you use sodium persulfate, it is best to keep the etching bath at around 45°C, this way the whole process doesnt take too long.
The tricky part is to get the two layers eactly on top of each other, as you can see i wasn't very sucessful. At least the offset is much smaller on the greater part of the board, i hope it wont be a problem as long as i solder carefully enough.

I've done about half of the resistors so far, im really slow because i try to be as pedantic as possible about checking each resistor with the layout before soldering. This way i hope to eliminate possible remaining errors.

I've never worked with tubes before, so maybe you can help me on the following. Im not sure if i overlooked some problem:

My idea was to change the tube heaters to 6.3V paralell. This is done by an additional resistor in the heaters power supply, pin 5 and 4 are connected to 6.3 volt and pin 9 is grounded. The reason for this is that i want to use russian 6n2p tubes, wich are equivalent to ecc83 except they only accept paralell heating (ecc83 accept both 12.6 and 6.3 volts). The power supply i got is a 12vac/1A, so it should handle the extra current. My only concern so far is that the bigger heating curretn adds more noise to this already noisy machine. Of course you can say its a bit pointless, since you can get ecc83's easily, but i have a couple of 6n2p-ev's lying around, i'm a cheapskate, and i like the irony of playing hippie music on some kind of good old russian military equipment.

I also got a question about the transformer. Blackbunny stated you could use a 15/230 trafo instead of the hard-to-get original 15/250. I think he is right, and maybe im a bit too pedantic, but the 15/230 has about 8% less winding ratio. So i want to use a 12/230 and reduce the primary voltage a bit with a resistor to be as close to the original as possible. What do you think? Do +/- 10% in the tube voltage even matter to the sound?

If you want to take a look at it, theres the modified layout and a simulation of the tube power supply i did out of curiosity in the attachments. Youll need a program like ltspice to open and run it.

Thanks to everyone who helped bringing this projects alive!

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Post by krueppel-keile »

i forgot, here you go:
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Russkisphere.zip
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Post by krueppel-keile »

Ok, i found something, if youre interested:
Ths guy replaced the momentary breaker switch on the rotosphere mk1 with a "normal" switch, this way you dont have to hold down the breaker switch all the time.
Its written in german, but has many pictures so you should get the idea.
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hk rotosphere taster gegen schalter.pdf
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StereoKills
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Post by StereoKills »

Is this project verified?

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Post by krueppel-keile »

Hey folks,
Sorry for not posting for ages, other stuff kept bothering me for a while. I completed the circuit around two moinths ago, and of course it didnt work first. I tossed it aside for a while and only checked on it now and then. Two days ago, i finally got it to work :D . I had many errors to trace and correct, no errors in the circuit or the layout (as far as i can tell), but many due to my almost non-existant soldering skills.
I cant say much about how well it actually sounds, since i only tested it with a crappy digital piano and headphones. I will plug it up to my organ and maybe a guitar when im at my bands place this weekend, to see how it works under real circumstances. Ill also need to find or build some kind of case till then.
The bass and treble rotor effect, together with the different speeds and accelerations work fine, and the distortion sounds ok so far. I still need to check if all the channels work, and how to fine-tune the 6 trimmers on the board.
After all, it was a quite frustrating job. As i said, i got many errors like bad connections, even broken opamps (yeah, it CAN happen). But im happy now that its complete.

Before i forget, i also used a 6n2p tube in my setup as i planned. But my suggestion on how to get the heater voltage was bad, the additional resistor created too much current for my power unit and broke it. i removed it and changed the two resistors in the heater circuit to 12 ohms (r209 and r210), it works well but the heater voltage is still abit to high, maybe ill find a better solution later. The whole thing runs on a 850mA power unit now without problems. And i use a fuse, it saved my new power unit a lot of times from unfortunate accident while testing.
Of course, everything should work as well if someone decides to build this and use the original tube without the modifications.

Ill let you know when everything is complete, and ill also post the layout as a pdf file for people who dont have the layout program.

Image
what a mess...

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Dirk_Hendrik
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Post by Dirk_Hendrik »

Krueppel,
You worded my first thoughts on the posted pictures in your post yourself already. Self knowledge and critisizm are great goods which many lack. I'm no saint either.
Therefore, compliments for your persistence going for a complex build like this one, and getting it to work. :thumbsup
Sorry. Plain out of planes.

http://www.dirk-hendrik.com

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Post by blackbunny »

Kudos to you for sticking with it and getting it to work; you will be rewarded by really good rotating speaker-like sounds when it's finished. :applause: :applause:

I have dozens of images of the original H&K circuit board, including close-ups or various areas showing component side and track side.
I can post images of any areas you're having trouble with, or PM them to you.

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Post by gobruins909 »

Did this project actually work? How much did all the parts cost???

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Post by krueppel-keile »

I bought the parts here and there and dont have all the bills at hand, but i estimate around 150€+-20. With so many parts, it really adds up. Of course, the frustration and headaches are priceless :)
I made a quick sound demo, the loud humming noise is a recording issue with my sound card. I dont have access to an original rotosphere or even a leslie and cant compare the sound, so what do you think? In my opinion it sounds too much like a tremolo (i expected more vibrato-like frequency shifting), but overall, its good enough for me. Especially like the tube distortion. I still dont have a decent case, but thats about to change in the next 2-3 weeks.
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test.rar
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Fredenando
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Post by Fredenando »

I'm no an expert, but I think you're on the good way. In the recording you can hear perfectly the two frequencies, the two independent speeds, as well as a very good distortion. But the other issue may be that lack the necessary Doppler Effect and not know if this can be because the recording is not done in stereo.

Maybe you can test with an stereo flanger after the Rotosphere to get some conclusions. (It's an idea...)

:applause: :applause: :applause: :applause:

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