The Organ Forum

There's another thread going about Carsten Meyer's Mig-T tube O/D which he stopped making. These guys are A) Make some more for them B)seeing if he will allow them to manufacture it themselves and C)seem to have found someone in the UK making them. Carsten also has a tube circuit to overdrive a leslie.

I think the Mig-T is for the T series organs, but it might be able to be used anywhere.

Have a peek at what the guys have to say...

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1970 B.T. Wright
1959 C3
1975 T-500
1992 Korg 01W/fd
1994 G&L S-500

Has anyone here actually made one of Kon's overdrives?

I saw jon's simplified version earlier this post, but Kon mentioned he had done one on a T using just two diodes and a switch to bridge pin 8 on the power amp and the ground/earth/shield. 

I'm trying to make the T-500 as dirty as yesterday's overalls, but I can't seem to get it to work. On is just the same as off.

I could just take it out and throw it on the lawn after a shower, but it seems too heavy for that.

The dirt should should be found from within the organ, I believe, Master San.

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1970 B.T. Wright
1959 C3
1975 T-500
1992 Korg 01W/fd
1994 G&L S-500

Speaking of Kon Zissis, the band he plays in has an OD'd organ and is on MYSPACE. They're called the Cosmic Nomads, heavy experimental seventies stuff with a bit of Heep and a bit of Focus, and a bit of something else altogether.

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1970 B.T. Wright
1959 C3
1975 T-500
1992 Korg 01W/fd
1994 G&L S-500

I emailed Kon re the T-series/ transistor organ overdrive. He allowed me to reprint his replies. I've tried just adding the zeners to the board (with a switch too) and resulted in a pleasing crackle in the leslie. It took six zeners. He suggested lower than 3.3, but they are hard to find. Also germanium diodes, but once again the local store doesn't carry them.

Here's the first of two emails:

Hi Brendon.
Thank you for your compliment about the Cosmic Nomads.
I have not  posted a circuit for the zener diodes overdrive unit  adopted to the T series organs, but you can try wiring  two zener diodes back to back in parallel between the pin 8 and the ground ( I think that pin 7 is a ground connection ) and then pull out the drawbars to '8' and then  play the organ at full volume. This should produce some degree of distortion.

The zener diodes should be IN4728 diodes which are rated at 3.3 volts in order for them to be able to distort the organ signal. Even better, see if your local electronics shop sells zener diodes  which have a voltage below 3.3 volts.

If the amount of distortion produced with the zener diodes is too little , then try wiring up a BAT 46 germanium diode back to back in parallel with the zener diode , or try wiring up two BAT 46 germanium diodes back to back in parallel and see how this sounds. 

All the best.
Kon

 

Here's his second email, with my questions included:

Hi Brendon
Q: The Nomads have the sound from the era I love the most.

A: The late 60's / early to mid  70's era is also my favourite music era which had all the great Rock / Heavy Rock / Progressive Rock / Psychedic Rock/ Funk / Blues etc bands.

Q: 3.3 zeners are the lowest they have at the store.

A: Apparently there are zener diodes that go down to 2.2 or 2.7 volts but 3.3 volts is the lowest that they have at my local electronics shop

Q: Seeing your name on the hammond wiki and both forums, you have reached some sort of celebrity status! Since you are a celebrity I should say "thanks very much!" and leave you in peace. 

A: Thank you for your kind compliments. I definitely do not think of myself as a 'celebrity'.

Q: What would happen with a few more than two?

The more diodes that are connected in parallel , the lower the threshold of distortion so therefore  a weaker signal can more easily be distorted.

A: The more  diodes that  are connected in series , the higher the threshold of distortion  so therefore  the signal needs to be stronger in order to cause the diodes to create the  distortion.

The AO28 preamp in the B3 , C3 etc produces a very strong signal so therefore the diodes need to be connected in series in order to produce a desirable level of distortion without severely clamping down the strong organ signal.

The T series solid state amplifiers produce weaker signals so therefore the diodes need to be connected in parallel so that they can adequately distort the organ signal.

Q: Also, me being an electronic initiate, does the end with the band face towards the 8 pin or away from it?

A: I do not think that it really matters because this is a passive application to clip and distort the organ signal.
The kathode ( negative) end of the diode has the band whilst the anode ( positive) end  is unmarked.

Here below two diodes are shown  as wired  back to back in parallel  as you would connect them between the signal  pin 8 and the ground pin 7 on the T-series organs :

             anode              kathode
                 |----------->|----------|
Pin 8 o-------|                       |------------o  Pin 7
                 |-----------|<----------|
               kathode      anode

Here below two  diodes are shown wired back to back in series:

--------->|----------------------------|<-------
anode  kathode    kathode    anode

 

All the best.
Kon

As a little extended project I'm going to try and recreate his full zener O/D but for a transistor organ, with knobs and sweetening capacitors and whatnot. I'm not remotely electronical, I'm reasoning my way via philosophy...  From his original circuit, the local shop also lacks a few of the other bits too...

My soldering iron broke last night when I was about to go hard on the project. I recall our school teachers telling us not to chew our pencils...

Cheers.

---

1970 B.T. Wright
1959 C3
1975 T-500
1992 Korg 01W/fd
1994 G&L S-500

bumpety bumpy bump

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Hammond B3
Hammond L-112
Hammond R-124
Hammond H-112
Hammond M2
Hammond 123
Hammond HR-40 tone cabinet
torn apart Gulbransen
Leslie 147
Roland Juno-G
Alvarez 12-string acoustic
Peavey Raptor electric

 Heh! One does what one must, eh shwagg?

Some of us are not only organ freaks, but also wailing guitar nuts.

Each instrument affects the way a guy plays the other. I'm looking forward to posting some recordings so show off my, er... prowess, but all in good time.

I've been tampering with my T-500, (the "portable" home organ. Still too heavy to stick under an arm!) the zener overdrive adds a nice growl, and I've been having trouble with the additional effects loop losuing treble, but I've been surprised by the dramatic effect found in EXTRACTING the spinet's internal leslie. I've made a big fat extension cord for it and built a big fat speaker housing for it and am about to cover that in amp "carpet" and then the chunky plastic corners.

The housing has to have holes in the right places, but the results are fantastic. Much more "leslie-like" than it is when muffled inside the body under the TWG. I didn't know these spinet half-leslies had it in them. The growl when it comes around once every rotation is gratuitous. Satisfying. Can't wait to sort the FX loop so I can stick it thru some guitar amp-head effects and rout it back thru the leslie.

If anyone hasn't the funds to get a leslie but wants to further monster up their spinet (with a great big speaker housing next to it making a leslie sound, who's to complain? Except for the wife and neighbours of course!) let me know and I'll divulge a few blueprints and suggestions!

In addition I could (at some stage) put up the info for posterity's sake under a separate post... for those new to the forum browsing the headings for the first time. 

 

---

1970 B.T. Wright
1959 C3
1975 T-500
1992 Korg 01W/fd
1994 G&L S-500

yeah i play guitar too myself, i don't like my great dexterity to waste whilst i'm away from the keys for extended periods of time. my favorite instrument second only to the hammond is the 12-string guitar, which i can't wait to hear through a leslie(though i've discovered using overdrive completely defeats the purpose of using a 12 string). once i get the motors up and oiled on the leslie i plan to experiment with all kinds of stuff.

i've been planning on taking the single rotor leslie out of a gulbransen i've gutted, but i haven't found the time(not to mention i completely forgot about it until rescently). but hopefully i can figure out a way to convert it to two speed, and perhap i cound find instructions for a homemade rotary horn assembly and turn it into my second full leslie caninet, and i could power it with my rocktron talkbox.

anyone have any 'diy leslie' expertise? i'd love to have a second leslie to toat around, and i'm sure some people would love to save money and just make one themselves.

lets all hope that a few more leaps can be made to make it easier for the beginner to attain "that sound", without paying the big bucks associated with "that sound".

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Hammond B3
Hammond L-112
Hammond R-124
Hammond H-112
Hammond M2
Hammond 123
Hammond HR-40 tone cabinet
torn apart Gulbransen
Leslie 147
Roland Juno-G
Alvarez 12-string acoustic
Peavey Raptor electric

Amp Heaven in the UK has very reasonably priced leslies, especially the solid state 720 which is dirt cheap. That amp would be a good option IF THEY REPLIED TO EMAILS, which they don't seem to. I'm sure they've put every one of my dozen or so requests into the spam bin.

I haven't found a DIY site yet myself but it's worth looking for. Ebay has the inner components of old leslies selling all the time....

Bullfrogmusic at least has a page on how NOT to do a diy leslie...

Anyone else found the dirt on DIY or cheap options?

Like I said earlier, as a cheap option, ripping out a spinet leslie and putting it in a housing still sounds great to the ear. especially when it's attached to the organ it came from: the bass is bypassed from these single rotor internal leslies and sent to the other internal speakers to simulate the separate speakers in a full leslie. These ones, at least in hammonds, are usually two speed, slow and fast.

What would happen if, for example the gulbransen leslie is attached to a different organ?
I think, among other things it would be necessary to ensure that only the pins it can use are made live, and those of course, hooked up to the right ones from the organ, in case from model to model or brand to brand, things have been put in a different order.

The two speed option involves a second motor. The core of the larger motor in my own one has a large wheel attached which the smaller motor then runs when the fast motor is off. Do you want photos of that? 

Was the gulbransen rotary speaker the usual polystyrene drum, or the rotosonic type?

---

1970 B.T. Wright
1959 C3
1975 T-500
1992 Korg 01W/fd
1994 G&L S-500

This a beautiful dirty sound - I'd love to know what was used.

Jump to 3:35 when the organ comes in:

http://www.youtube.com/watch?v=h4igq87wwVo

Brendon Wright:

What would happen if, for example the gulbransen leslie is attached to a different organ?

Nothing special. Audio signal would be always an audio signal.

Brendon Wright:

There's another thread going about Carsten Meyer's Mig-T tube O/D which he stopped making. These guys are A) Make some more for them B)seeing if he will allow them to manufacture it themselves and C)seem to have found someone in the UK making them. Carsten also has a tube circuit to overdrive a leslie.

I think the Mig-T is for the T series organs, but it might be able to be used anywhere.

I've build a clone of MIG-L preamp (the one for Leslie, I used it with 760). The tube don't distort the signal as much as CMOS chip used there. The tubes operate with really low anode voltage, and directly heated, may be easily broken, even by vibrations. MIG-T was designed for different voltages (it acts as an low-voltage preamp). It won't work with C3.

Why don't you simply buy a cheap tube guitar amp off ebay or something like that? Even the cheap Epiphone Valve Junior would do that trick. Or Orange Tiny Terror if you need more control over the sound. You can connect it's output directly to your Leslie speaker disconnecting its internal amp altogether (you should use an crossover if it was an amp with separate hi/low amps like 760). Always search for the simplest solution.

Jon 

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I hate jazz!

Cheers Jon.

I was wondering about (for example) shwaggety's  gulbransen because I noted that the internal drum on my T-500 doesn't take the whole signal, a portion of it is split off and still goes to the  other speakers (the bass portion, according to some web page I found somewhere).

If the whole signal was to go thru the single rotor, with all bass and treble "wah"-ing at the same speed, the whole effect of it sounding "Leslie-like" might be spoiled. I believe the new ones made by... sound motion? Motion sound? Whoever, simulate the bass rotor spinning as well, not JUST splitting it off but simulating the motion of the real deal leslies.

On overdrive, the simplest solution was to get the experts to do the work for me!

I liked the basic Zener overdrive idea Kon had suggested... I used a few more than he suggested, but it was just putting a few of the diodes at the input to the power amp (in parallel, every second one reversed polarity) with a switch to disable them again. It was a mild overdrive, just a growl in the bass.

When I put a loop in as well, the combined wiring between the pin and its mate (because they had to be separated to create the loop) mellowed the organ sound completely, losing all treble. Useless.

Kon posted a FET buffer diagram for me on Hammondzone, but I can't read circuit diagrams! (I needed a pic of a circuit board. Perhaps I need to get a book out of the children's library on electronics, and learn!) This boosts the signal so it comes out the same as it goes in, without losong tone.

I met our local amp repair guy who deciphered it for me and suggested modifications.

Then because I continued to look stupid, he made it up for me on the spot for no charge!

I'll install it this weekend.

Now I can put my guitar effects into the loop. They're digital amp models rather than valves, but I'll have to make do for now. 

I look forward to messing with the sound somewhat....

I consider I'm a 70's rocker, and a relatively flashy player, but It'll be a while before I have time to record anything.........

Cheers.

-Brendon

---

1970 B.T. Wright
1959 C3
1975 T-500
1992 Korg 01W/fd
1994 G&L S-500

i've been considering the epiphone valve junior. does it get overdrive similar enough to a leslie? i want to make sure i make the right purchase, because i'm not sure if my next buy would be the valve junior or an acoustic amp for my 12-string guitar.

---

Hammond B3
Hammond L-112
Hammond R-124
Hammond H-112
Hammond M2
Hammond 123
Hammond HR-40 tone cabinet
torn apart Gulbransen
Leslie 147
Roland Juno-G
Alvarez 12-string acoustic
Peavey Raptor electric

I don't know the answer to that Shwag. You'll have to try before you buy! 

I have just tried my organ  from the mono line out (in the case of the T-500, a headphone jack on the speaker cloth rather than the RCA on the swell control of the C3) to my mos-fet guitar amp. It took a lot of fiddling to get rid of the sheer noise and the tone right.

I realise that Jon Lord must have often just used the organ vibrato with his marshall overdrive rather than using the swirling of the leslie. It seems to have that Lordly sound, anyhow.

An acoustic amp might double for synth foldback, I think, if you play synth at all, electric guitar amps are shocking in that respect. 

The only way to know for sure is to appro the epiphone and plug the organ through it.

The truth about amps is that cheap options leave you with nagging uncertainties. Buying the real thing guarantees the result, but costs far too much for what amounts to an obsessive hobby.

When there's money, the search for perfection is unending. 

 

 

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1970 B.T. Wright
1959 C3
1975 T-500
1992 Korg 01W/fd
1994 G&L S-500

To get warm, nice distortion the tube guitar amp is the only solution. Mosfets won't work. Sorry :)

---

I hate jazz!

---

1970 B.T. Wright
1959 C3
1975 T-500
1992 Korg 01W/fd
1994 G&L S-500