Hudson Electronic Broadcast  [traced]

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Re: Hudson Electronic Broadcast

Postby andy-h-h » 15 Aug 2018, 21:53

marshmellow wrote:Yes, you can build it without the transformer. But it's not in the circuit to provide isolation (as drawn it doesn't), it is there to form the sound. In comparison to an overdriven guitar sound, transformer distortion is very subtle, its contribution might be minimal anyway. These little transformers usually also have very limited bandwidth, so to mimic the sound of the original pedal, you will probably have to introduce at the very least some bass cut.


Thanks for that marshmellow. Think the bandwidth is 200hz to 15k on that transformer. I'll give it a try without the transformer and see what happens while I wait for the transformers to arrive. Bit of an odd design for what it appears to do.
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Re: Hudson Electronic Broadcast

Postby Intripped » 26 Aug 2018, 19:16

hello,
i'm ordering some parts from Banzai music and Musikding, and i see that they sell germanium transistors as well; they also offer some kind of hfe selection.

i would like to buy a couple of transistors to try in this circuit, but i really need some help in the choice.
what transistor would you buy? what Hfe?

here are the links, i thank you in advance for your help:
https://www.musikding.de/Germanium-Transistors
https://www.banzaimusic.com/Germanium-Transistors/
https://www.banzaimusic.com/Transistors-matched-selected/
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Re: Hudson Electronic Broadcast

Postby johnk » 26 Aug 2018, 20:05

IMO an OC75 from musikding with an hfe of 50-60 would work well.
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Re: Hudson Electronic Broadcast

Postby Intripped » 26 Aug 2018, 21:36

great! (even if i was hoping for something a bit cheaper...)
i will order it then, and report back
thanks!
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Re: Hudson Electronic Broadcast

Postby teddeeh » 29 Aug 2018, 09:53

Any info on the dual? I have one ordered so should arrive next month after speaking to andertons yesterday. The last batch they only got 50 and i am no. 54 on the list. So no.4 if this batch dosent have extras.
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Re: Hudson Electronic Broadcast

Postby andy-h-h » 18 Sep 2018, 08:46

Hello,

Can anyone explain to me where the filtering is happening between the output of Q2 and the transformer? I have something pretty close to full range up to the 15k resistor, and a fair bit of bottom end drops away after that. I've tried working out where the filtering is happening, but my calculations are clearly wrong, as they don't account for what I'm hearing and seeing on the spectrum analyser.

Using JohnK's vero / schematic.

Thanks
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Re: Hudson Electronic Broadcast

Postby plush » 18 Sep 2018, 10:12

andy-h-h wrote:Hello,

fair bit of bottom end drops away after that


Did you consider checking the frequency range of the transformer (ty-141p)?
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Re: Hudson Electronic Broadcast

Postby andy-h-h » 18 Sep 2018, 10:18

plush wrote:
andy-h-h wrote:Hello,

fair bit of bottom end drops away after that


Did you consider checking the frequency range of the transformer (ty-141p)?


Hello - The low end drop-off is happening before the transformer. I can take signal from after the 10uf capacitor, but before the 15k resistor, and it's full-range. After the 15k resistor, and the low end has disappeared somewhat. I just updated the schematic above to show where the filtering is happening. Maybe it's related to the transformer, but it seems to be happening before it.
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Re: Hudson Electronic Broadcast

Postby plush » 18 Sep 2018, 23:19

andy-h-h wrote:
plush wrote:
andy-h-h wrote:Hello,

fair bit of bottom end drops away after that


Did you consider checking the frequency range of the transformer (ty-141p)?


Hello - The low end drop-off is happening before the transformer. I can take signal from after the 10uf capacitor, but before the 15k resistor, and it's full-range. After the 15k resistor, and the low end has disappeared somewhat. I just updated the schematic above to show where the filtering is happening. Maybe it's related to the transformer, but it seems to be happening before it.



Image

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Re: Hudson Electronic Broadcast

Postby andy-h-h » 19 Sep 2018, 08:27

Thanks Plush, I was completely unaware of this kind of filter. :thumbsup

So one side of the transformer is providing inductance, resulting in a filter when combined with the resistor. I'll have a play with some resistor values and see what happens.
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Re: Hudson Electronic Broadcast

Postby teddeeh » Yesterday, 23:33

So i got my dual hudson in the post today
Here are images of the top and underside of the board.
If anyone wants to trace i will do my best to measure the parts or give readings etc.
That is im assuming a suppression cap on the dc in. The markings say “R005 B8RS”
Trimmers are both 102
Smallest elec cap 10uf @50v
Next size 100uf 25v x3
Second largest size 330uf @16 v (in the middle and this is a 24v pedal..? ) And the second is a 120uf on the right @25 v
Biggest badboy is a 220uf @35v

603B3B3F-99FA-4126-A2AD-86F14857B9C3.jpeg
232132B1-76AC-4A69-9D71-A55FCF1FC8D5.jpeg
9C90B1C3-4452-4EDC-90F4-77DAC365F2EA.jpeg
0F8BD5F6-B745-4242-906F-F2C50E30D4E2.jpeg
1F90AC96-9C30-488F-B2C1-90855C5C4E0B.jpeg
1F90AC96-9C30-488F-B2C1-90855C5C4E0B.jpeg
E1D29AC9-1C74-46E5-AEF3-075DD962F509.jpeg
ACD9E751-6EF4-4B67-A6C1-9456F1ED8802.jpeg

A323E249-90A7-437D-A5D5-9FA2841C8B24.jpeg
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