Parallel loop - for ampgarage users only :-D

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bluesfendermanblues
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Parallel loop - for ampgarage users only :-D

Post by bluesfendermanblues »

Hey 'Loop' Guys

I have fine tuned my build-in loop.

The design goal was

1) In serial mode - as close to the 'original' schematic as possible
2) In Parallel mode - as transperent as possible AND with same level in the circuit as when bypassed.

So this is what it looks like - enjoy

Its tested in my amp and I it works really good - for studio use as well as at gig levels.

PS: for ampgarage users only
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Structo
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Re: Parallel loop - for ampgarage users only :-D

Post by Structo »

Thanks Claus!

For continuing to work on this.

I think there is a little mistake though.
The second tube stage (V1b) you have the signal going to the cathode, should go to the grid, yes?
Tom

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bluesfendermanblues
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Re: Parallel loop - for ampgarage users only :-D

Post by bluesfendermanblues »

Structo wrote:Thanks Claus!

For continuing to work on this.

I think there is a little mistake though.
The second tube stage (V1b) you have the signal going to the cathode, should go to the grid, yes?
Yeah sorry 'bout that its a typo. I'll post a correct version later.
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stevlech
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Re: Parallel loop - for ampgarage users only :-D

Post by stevlech »

Thank you!!!!!
bluesfendermanblues
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Re: Parallel loop - for ampgarage users only :-D

Post by bluesfendermanblues »

bluesfendermanblues wrote:
Structo wrote:Thanks Claus!

For continuing to work on this.

I think there is a little mistake though.
The second tube stage (V1b) you have the signal going to the cathode, should go to the grid, yes?
Yeah sorry 'bout that its a typo. I'll post a correct version later.
Here's the corrected Schematic.

It really works really great

I've build it into an amp. Its completely quiet in parallel mode. However, in serial mode its a bit noisy, due to the fact, that I didnt use schielded cable for the grid wires like I should have ...according to all the pictures of people's dumbleators, they all use shielded wiring. I didn't think it would be nessesary for a build in loop, but it is. I'll correct that in my amp today.
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Sven
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Re: Parallel loop - for ampgarage users only :-D

Post by Sven »

THANK YOU ! This is a very valuable contribution. Do you have any layout drawing as you have used it in your amp?
bluesfendermanblues
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Re: Parallel loop - for ampgarage users only :-D

Post by bluesfendermanblues »

Sven wrote:THANK YOU ! This is a very valuable contribution. Do you have any layout drawing as you have used it in your amp?
I used NORMSTER's layout for inspiration and just put in my own design elements in there.

Will post pictures of my amp later. It has dual od sections and a lot of relays and wiring, so I'll clean up the wiring a little bit prior to posting :-)

However, take a look at Normsters layout for inspiration and put the parallel mods in.
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Structo
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Re: Parallel loop - for ampgarage users only :-D

Post by Structo »

BTW, I really hated that .001uF bright cap. Way to much high end.
I made the value much smaller.
Can't remember the exact value, either 500pf or 330pf.
Tom

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renshen1957
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Re: Parallel loop - for ampgarage users only :-D

Post by renshen1957 »

bluesfendermanblues wrote:
The design goal was

1) In serial mode - as close to the 'original' schematic as possible
2) In Parallel mode - as transperent as possible AND with same level in the circuit as when bypassed.
Hi, very nice work.

The loop reminds me of the "Best All Tube Effects Loop" that was in first book of The Ultimate Tone series by Kevin O'Connor (published 1995). O'Connor's take also added the option of Guitar Level or Studio level (-20db or 0db) in addition to the series-parallel option. His circuit used a SPST switch to use alternate between the series-parallel setting.

Best Regards,

Steve
bluesfendermanblues
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Re: Parallel loop - for ampgarage users only :-D

Post by bluesfendermanblues »

renshen1957 wrote:
bluesfendermanblues wrote:
The design goal was

1) In serial mode - as close to the 'original' schematic as possible
2) In Parallel mode - as transperent as possible AND with same level in the circuit as when bypassed.
Hi, very nice work.

The loop reminds me of the "Best All Tube Effects Loop" that was in first book of The Ultimate Tone series by Kevin O'Connor (published 1995). O'Connor's take also added the option of Guitar Level or Studio level (-20db or 0db) in addition to the series-parallel option. His circuit used a SPST switch to use alternate between the series-parallel setting.

Best Regards,

Steve
So what Sherlock :roll: I've read Kevin O's book TUT1 a number of times as well as used a lot of other sources. Kevin didn't exactly invent the cathode follower amp for the 'send' nor the Single-Stage Inverting Feedback Amplifiers: http://aikenamps.com/FeedbackAmp.htm for the 'return' amp either.

You don't need a (KOC) 20db/0db in this loop. The range of the return control is plentyfull for both pedal effects return levels as well as rack effects ditto.

However, should you decide in favour of the KOC '20db/0db', you might want to add caps across the 100k/1M resistors in order to get the Dumble bright boost (1442Hz). Use a 100pf across the 1M resistor and 1nf across the 100K.
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Sven
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Re: Parallel loop - for ampgarage users only :-D

Post by Sven »

I have tried to make a LAYOUT for this scheme, and without following any rules and/or very smart tricks, I have drawn this, so that people could see and perhaps comment. Attached drawing.

EDIT: corrected V3-7 connection on February 9, 2010.

[/img]
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Structo
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Re: Parallel loop - for ampgarage users only :-D

Post by Structo »

I tried my hand at Visio.
Be gentle, it's my first one.
The layout could probably be better as far as component placement.

Perhaps having the Bypass and Series/ Parallel on the back would be a better placement because you most likely won't be messing with those two switches much, plus the wire runs will be shorter.

Layout updated and a few value errors corrected. 2/24/10

Please verify with the schematic before using this layout. I tried to weed out the mistakes but it still might have one.

I've taken this layout off of the board so I can correct some things.
Don't refer to this layout if you are building one.
This refers to all versions including this one ver. 4.
Last edited by Structo on Fri Feb 26, 2010 7:17 pm, edited 1 time in total.
Tom

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Sven
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Re: Parallel loop - for ampgarage users only :-D

Post by Sven »

Well, first of all, on the above layout done by memeber ¨stucto¨ in Visio, the connections to the valve at V3-2 and V3-3 should be reversed, right on the valve pins. Simple. Meaning, the light blue wire from 0,05uF capacitor should go to V3-2 and not to V3-3. That also calls for orange wire from 0,47uF cap, to go to V3-3 and not to V3-2.

BTW, why not use standard color coding for wire: red for plates, black for cathode and blue for grids, to make it more elegant, simple and proper (as I have used it above)?

And also, on the above Visio layout, V3-7 is not connected according to the schematics. I think V3-7 is connected correctly on my layout.

I have posted above a layout that should be OK with the schematics.

RECOVERY pot is not in the schematics, but one could guess that it is possible to install it. Cannot check it now.
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Structo
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Re: Parallel loop - for ampgarage users only :-D

Post by Structo »

Thanks Sen, as I said sometimes it takes a second pair of eyes to see something.
Constructive criticism is always welcome.

The reason I made this layout is because yours is bit hard to see how everything comes together since you really aren't showing a layout of the parts for a stand alone D'Lator.

All real Dumbleators have have been made with the socket in the middle of the board.

I am not familiar with your nomenclature in regards to the pin numbers.
Since this device only has one tube, why not just call out the pin numbers?

I will work on this later and try to correct the errors and lay the parts out a bit better.
You are right about the wire colors, I was trying to make a contrast so they would be easy to see.
I will correct those to common color code.

As far as the Recovery pot, it has been shown in most of the later schematics here so I included it, even though the schematic that Claus drew does not contain it, it has been found to be a good thing on the loop so I will include it.
Tom

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Sonny ReVerb
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Re: Parallel loop - for ampgarage users only :-D

Post by Sonny ReVerb »

Structo wrote:I am not familiar with your nomenclature in regards to the pin numbers.
Since this device only has one tube, why not just call out the pin numbers?
As far as I can decipher, most of the pins are numbered (e.g. V3-7 means pin 7 of valve 3). V-A and V-B go to the dropping string.
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