[SCH] Xmas gifts! (schems inside) LAST PART

Zero the hero · December 16, 2005, 05:56:36 AM

Bernardduur · December 16, 2005, 06:24:28 AM

Wow..... that is one cool effect......

I never heard of it at first, than I read this:
"EH Designer Howard Davis came up with the AMBITRON, a unit to synthesize a stereo effect from a mono input. It was available in at least 2 forms: the floor unit made for guitar use and a rackmount stereo unit for home stereo use. Howard says he designed the Ambitron to get a stereo effect from his mono jazz LPs. Good show, Howard!"

Now I want one!

stm · December 16, 2005, 07:31:20 AM

Nice and interesting!

After looking at the cricuit for a while I noticed the following:

1) It has two SAD1024's with all their stages chained and no feedback. This can be readily replaced by an MN3008 or BL3208 at a much reduced cost.

2) It uses the classical NE570 compander for noise reduction--good.

3) The schem doesn't include the clock circuitry. You can see the PHI_1 and PHI_2 indications on the SAD's clock inputs only. My guess is that this clock should be somewhere between 20 kHz and 40 kHz. I don't think of a higher clock, because if short times were needed I don't see the purpose of using two expensive SAD's in series.

4) Interesting by itself is the "Stereo Separation Enhancement" part of the circuit, formed by the two opamps on the upper-left of the upper SAD. Take a look ate the proportions in which the L & R channels are mixed, PLUS the different capacitor values (frequency dependent), and plus the high frequency bleedtrhough 0.0012 uF cap where the (.4R-L) and (.4L-R) labels are. Certainly worth some simulation

Thanks.

Marcos - Munky · December 16, 2005, 08:03:36 AM

Cool. Thanks a lot.

StephenGiles · December 16, 2005, 08:23:58 AM

I have what may be a prototype circuit for what I think is called EH Quad Synthesiser, I havn't looked at it for a long time. I'll dig it out to see if it bears any resemblance to this one. I'm sure it's from Howard Davis though.
Stephen

StephenGiles · December 16, 2005, 08:26:30 AM

Munky - words from English country song:
Lumberjacks are big and tough
And truckers even stronger
But we know when it comes to ridin'
That cowboys stay on longer!

Stephen

kusi · December 16, 2005, 11:11:11 AM

thanks a lot, zero by hero!

happy christmas!

Golden Drive

greetings,
KHE

Phorhas · December 16, 2005, 11:38:32 AM

Thank you very much.

toneman · December 16, 2005, 01:14:52 PM

Many thanX Zero!!

I've been looking 4 that schemo....!!

Kusi, can't get 2 your Golden Drive.
needs a password...

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Merry C!
from T

kusi · December 16, 2005, 01:31:17 PM

Quote from: toneman on December 16, 2005, 01:14:52 PM

Kusi,Â can't get 2 your Golden Drive.
needs a password...

oh, sorry, waite some minutes.....

greetings,
kusi

edit;
works?

StephenGiles · December 16, 2005, 03:44:48 PM

Zero, could you give me a clue as to what scanner settings you used for this one, my copy of the EH Quadriphonic (funny spelling!) Synth looks as if it has been reduced considerably, and in order to get a sensible file size for Photobucket the circuit is very difficult to read.

The clock driver is just a 4047 + 2 caps and a resistor!
Stephen

Mark Hammer · December 16, 2005, 03:49:36 PM

This 1981 pricelist ( http://ampage.org/hammer/files/1981_E-H_pricelist.gif ) shows the Ambitron was selling for $185 on sale.

stm · December 16, 2005, 03:52:00 PM

Quote from: kusi on December 16, 2005, 11:11:11 AM
thanks a lot, zero by hero!

happy christmas!

Golden Drive

greetings,
KHE

Curious schematic. Looks like there is no high filtering capacitor after the opamp. After C7 there is a 100k to 4.5V with a 1k in series, then another 100k to 4.5V, then C8 (22uF), then another 100k to ground. Â Looks like R8, R10 and C8 could be taken out of the circuit without impact.

toneman · December 16, 2005, 04:38:26 PM

Kusi,
works good now.
looks like another TS version

thanx
Merry C
T

Marcos - Munky · December 16, 2005, 04:55:27 PM

Quote from: StephenGiles on December 16, 2005, 08:26:30 AM
Munky - words from English country song:
Lumberjacks are big and tough
And truckers even stronger
But we know when it comes to ridin'
That cowboys stay on longer!

Stephen

What's the name of this song? It have a cool verse.

StephenGiles · December 16, 2005, 05:26:18 PM

It's called Cowboys Stay on Longer written by Hank Wangford
http://www.hankwangford.com/
Stephen

TheBigMan · December 16, 2005, 06:45:16 PM

Quote from: stm on December 16, 2005, 03:52:00 PM
Quote from: kusi on December 16, 2005, 11:11:11 AM
thanks a lot, zero by hero!

happy christmas!

Golden Drive

greetings,
KHE

Curious schematic. Looks like there is no high filtering capacitor after the opamp. After C7 there is a 100k to 4.5V with a 1k in series, then another 100k to 4.5V, then C8 (22uF), then another 100k to ground. Â Looks like R8, R10 and C8 could be taken out of the circuit without impact.

My first thought when I looked at it was the quad opamp version of the Boss OD-1 without the static tone control.

Zero the hero · December 19, 2005, 06:51:29 AM

Quote from: StephenGiles on December 16, 2005, 03:44:48 PM
Zero, could you give me a clue as to what scanner settings you used for this one, my copy of the EH Quadriphonic (funny spelling!) Synth looks as if it has been reduced considerably, and in order to get a sensible file size for Photobucket the circuit is very difficult to read.

The clock driver is just a 4047 + 2 caps and a resistor!
Stephen

I used an HP Scanjet 2200c
100dpi
256 levels of gray
Then some photoshop for improving contrast and scaling it down a bit.

Marcos - Munky · December 19, 2005, 08:05:17 AM

Wow. This Korg Synth is a beast!!! Who will be the first one to do a layout for it and build a clone?

StephenGiles · December 19, 2005, 02:51:54 PM

This is the best I can do from a poor copy I have of the EH Quadriphonic Amp + Synthesiser. This is dated a few months prior to the Ambisonic, so most likely a prototype. Merry Christmas!
http://img.photobucket.com/albums/v517/uncle_boko/EHquadsynth.gif
Stephen

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[SCH] Xmas gifts! (schems inside) LAST PART