Darkglass - Vintage Microtubes  [schematic]

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

Re: Darkglass - Vintage Microtubes

Postby johnk » 12 Apr 2017, 05:05

i drew up an etchable pcb for it, but i want to test it first before i post it, but i'm pretty sure that i got it right.
i used own the original and i remember well how it sounded so i should be able to tell if it sounds like the orig.
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Re: Darkglass - Vintage Microtubes

Postby johnk » 13 Apr 2017, 00:37

okay. i built and tested it and it works perfect except the 'era' control is nowhere near as effective as on the original. IMO, there must be something amiss in the schematic.
i i tried it both ways as per these schematics and neither way is like the original pedal.:
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Re: Darkglass - Vintage Microtubes

Postby johnk » 13 Apr 2017, 07:00

hmmmm. Darkglass describes that the era interacts with the Drive knob to shape the character of the pedal, but i don't really see how it can, being that it's located post the drive/distortion part of the circuit as per the posted schematic.
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Re: Darkglass - Vintage Microtubes

Postby Frank_NH » 13 Apr 2017, 18:01

johnk wrote:hmmmm. Darkglass describes that the era interacts with the Drive knob to shape the character of the pedal, but i don't really see how it can, being that it's located post the drive/distortion part of the circuit as per the posted schematic.


Just perusing this on my lunch hour. It looks to me that the Era control is just a variation on the BMP tone control. But...it's missing a resistor to ground at the junction of lug 3 and C21 in the first schematic. That resistor would form a HPF with the 1 nF cap when the Era control was all the way up. I don't know if there is a gut shot somewhere, but you could look for a resistor near the 1 nF. Otherwise experiment (start with something like 100K to ground, and go up from there to retain more lows).

The last two op amps are Sallen-Key filters to chop off the high end somewhat, probably a good thing since this is being used for bass...
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Re: Darkglass - Vintage Microtubes

Postby johnk » 13 Apr 2017, 18:10

yeah, i was going to try adding a resistor to it.
i also just ordered a GUMA antique overdrive which is supposed to be an accurate clone of the VMT and i intend to trace it to see if it matches the posted schematics.
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Re: Darkglass - Vintage Microtubes

Postby Silver Blues » 13 Apr 2017, 18:17

It was actually from pictures of that board that I determined the missing capacitor values. I was just looking at it again to see if I could figure out the connectivity, but there's only so much I can do without having the physical board in front of me. As far as I can tell right now Era 2 and Era 3 are actually connected to each other, don't know if that helps.
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Re: Darkglass - Vintage Microtubes

Postby johnk » 13 Apr 2017, 19:19

i think that ERA 2&3 are connected together too. it may be wrong cap values but the GUMA antique appears to have the same values in the BOM.
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Re: Darkglass - Vintage Microtubes

Postby johnk » 13 Apr 2017, 19:21

i think that ERA 2&3 are connected together too. and yes the GUMA antique has those values in the BOM.
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Re: Darkglass - Vintage Microtubes

Postby stangwarrior » 20 Apr 2017, 09:03

Just completed ksenanekro's version and it works ok.Two of the pot as reversed - you should swap blend 1 and blend 3, and drive 1&2 should go to volume 1.ERA works as it should i think, tho i don't own the original and can't compare...
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Re: Darkglass - Vintage Microtubes

Postby miguelmoita » 21 Apr 2017, 19:29

Here is the my schematic based by the ones the johnk did with the values of Guma Antique. There are very few adjustments. I have it in my breadboards and it sounds awesome but I do not have the original to compare. I own the B7k, and it definitely sounds like a Darkglass.
I am going to make a tone transfer image in the next days, I will post here.
Regards,
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Re: Darkglass - Vintage Microtubes

Postby miguelmoita » 02 Jun 2017, 05:39

Just finished Mine :)

Sounds awesome!
Just needs the decals now.
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Re: Darkglass - Vintage Microtubes

Postby fersynes » 22 Jul 2017, 06:55

miguelmoita wrote:Just finished Mine :)

Sounds awesome!
Just needs the decals now.


wow! it looks so good! and the board is very similar to you b3k. could you please upload the layout and pcb?
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Re: Darkglass - Vintage Microtubes

Postby vadgrek » 04 Aug 2017, 12:51

miguelmoita wrote:Just finished Mine :)

Sounds awesome!
Just needs the decals now.

Psb!.. Psb!..Psb!.., :applause: :applause: :applause:

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Re: Darkglass - Vintage Microtubes

Postby horacemap » 25 Aug 2017, 17:33

Just finished mine too.

Sounds really great. Super bassy with a touch of growl :D

Thanks for sharing the layout !!

d00137fc-94fc-4068-85f8-ead0759a04c8.jpg
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Re: Darkglass - Vintage Microtubes

Postby bajaman » 26 Aug 2017, 00:15

I just built the B3K which is very similar to the VMT :wink:
I have some boards available if anyone is interested - pm me :secret:
cheers
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Re: Darkglass - Vintage Microtubes

Postby stangwarrior » 23 Oct 2017, 10:13

Hi,
anyone have issues with this build?I have two problems - one is the gain, which squeeks and cuts the sound after 80-90%, the other is whatever i do, it sounds dephased in a wierd way, very artificial...The only difference in my build is i use j113 transistors instead of j201 and the unused inputs of the CD4049 are not grounded
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Re: Darkglass - Vintage Microtubes

Postby stangwarrior » 25 Oct 2017, 09:31

Anyone? 3 builds allready and always the same problem - it sounds like high pitched shit, especially when you play on the hight strings...
Are you sure some of the opamps stages should invert the signal?Isnt the signal inverted after the CD4049 and the out of phase with the clean signal?
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Re: Darkglass - Vintage Microtubes

Postby Paul_5 » 16 Mar 2018, 19:37

horacemap wrote:Just finished mine too.

Sounds really great. Super bassy with a touch of growl :D

Thanks for sharing the layout !!

d00137fc-94fc-4068-85f8-ead0759a04c8.jpg


Is it possible you could post voltages at your IC pins? I've finished building this and the clean works, as do all of the controls, but there's not much bass signal going through, almost as though the bass signal isn't clearing Q1.

Thanks on advance.
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Re: Darkglass - Vintage Microtubes

Postby Paul_5 » 17 Mar 2018, 01:04

Paul_5 wrote:
horacemap wrote:Just finished mine too.

Sounds really great. Super bassy with a touch of growl :D

Thanks for sharing the layout !!

d00137fc-94fc-4068-85f8-ead0759a04c8.jpg


Is it possible you could post voltages at your IC pins? I've finished building this and the clean works, as do all of the controls, but there's not much bass signal going through, almost as though the bass signal isn't clearing Q1.

Thanks in advance.


SORTED - it was a dicky JFET at Q1.

Lovely sounding pedal this, just been having a bit of a 'do' with my Jazz bass with flat wounds - very retro sounding.
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Re: Darkglass - Vintage Microtubes

Postby psychepool » 27 Mar 2018, 07:49

I sucessed to make it with 1590A!

7721517D-A95B-434B-9AEB-936CDB2AB757.jpeg


DF0C510A-E0DD-4FDF-93CB-C38B04306A8D.jpeg


I have done a lot of worry since I created the perfboard layout.
The board size was too large to guarantee that it would be housed in the 1590A case.
Fortunately, it was not easy, but it was housed.

EC3801FA-0DB3-448D-A195-258CD3B5B584.jpeg


I made it with the above layout.
Note the size of the film cap, the height of the electrolytic cap, and the IC sockets.

The size of the film cap varies from product to product. Particular attention should be paid to 220n and 1000n.
The lead spacing should be 5mm and should be as small as possible.
If the 1000n cap is oversized, use a monolithic 1uF. It will be operate with no other problem. However, I can't guarantee sound differences.

About the electrolytic cap, there will be 7mm high model. If the product is 25v or 50v, it will not be a problem.

The IC socket should also be careful, as you can see the layout of the parts that pass under the IC.
With such a dedicated socket, you can not place parts under the IC.
It is necessary to obtain such a one-row socket and cut it as necessary and put it in two lines so that the part can be stored under the IC.
https://www.littlebirdelectronics.com.a ... -00743.jpg

If you can cut the corners of the board, cut them as far as you can and hopefully work.
The inner wall and bottom plate of 1590A case should be insulated with insulation tape.


I do not want to recommend it because it is so hard to put in. And I also do not want to make it again.
But obviously the behavior has been proven, so if you have a strong desire to make smaller, you might want to try it.
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