Lou Dorren: A new CD-4 Demodulator!!! [ARCHIVE]

[JonUrban]

Wow! A CD-4 demodulator from 2011. What will the historians think?

Very cool. Can't wait to check it out.

 

[jefe1]

Yes, Lou's demodulator will confuse future archaeologists.

 

[scratch17]

Hi Lou:

Could you clarify a few things, please.

1. Is the Line input a straight pass-through? Does it bypass RIAA equalization? Could you record a CD-4 in stereo (doing A/D conversion to 24/96 resolution) and send that recorded file (after D/A conversion) to the line inputs of the demodulator for later decoding to quad?

2. I thought that this unit was designed for use only with your stylus, which I understood to be a moving magnet design. Yet I see a moving coil input selection. Does this imply that you can use the demodulator with a MC cart that is flat to 50khz, so it can pass the carrier to the demodulator?

3. What is the SC input's purpose?

Thanks, Steven.

 

[Quad Linda]

SC means a semiconductor, or non-magnetic phono cartridge. Many budget oriented Quad setups featured this technology, especially those sold with a CD-4 cartridge included. Many of these models also had a built in demodulator.

Lou would need to answer the other two questions.

Linda

Hi Lou:

Could you clarify a few things, please.

1. Is the Line input a straight pass-through? Does it bypass RIAA equalization? Could you record a CD-4 in stereo (doing A/D conversion to 24/96 resolution) and send that recorded file (after D/A conversion) to the line inputs of the demodulator for later decoding to quad?

2. I thought that this unit was designed for use only with your stylus, which I understood to be a moving magnet design. Yet I see a moving coil input selection. Does this imply that you can use the demodulator with a MC cart that is flat to 50khz, so it can pass the carrier to the demodulator?

3. What is the SC input's purpose?

Thanks, Steven.

 

[surroundme33]

Very nice! Would love to see the back side. I'm curious what outputs are available. Will there be an analog 5.1 output (rca/phono) outs?? Would of been cool if somehow you can hook this up to a modern multi-channel amp fit for 5.1.. Maybe featuring a crossover for the LFE (80/100/120)..

 

[vinylguy4]

Hi Lou:

3. What is the SC input's purpose?

SC - Semi Conductor
That was used on the Technics/Panasonic demodulators (e.g. SH-400) for the Strain Guage cartridges.
Panasonic EPC-450C-II was an example. Soundsmith makes a modern version of the cartridge.

vinylguy4

 

[bmoura]

SC - Semi Conductor
That was used on the Technics/Panasonic demodulators (e.g. SH-400) for the Strain Guage cartridges.
Panasonic EPC-450C-II was an example. Soundsmith makes a modern version of the cartridge.

vinylguy4

The Panasonic EPC-450C-II seems like a bargain if you compare it to the prices of the Soundsmith SC systems. Wow !

 

[loudorren]

Hello Q-folks,

jefe1,

Sorry but the meters are only available in white.

scratch17,

The input-output structure follows the request of the QQ members. The Line input is flat with no RIAA EQ for those who want to experiment with digitized playback. The input select covers semiconductor (SC), moving magnet (MM) and moving coil (MC) pickups. If you have a pickup that has at least 10dB separation @ 50KHz it should work well.

surroundme33,

I am getting on my soap box for a moment. There is nothing modern about 5.1. It is a sham created by the Dolby people to eliminate full range loud speakers. Bass is directional and one base speaker will not do it. In addition dialog speakers are useless and serve no purpose if the mixing engineer knows how to use the phantom channels. The Dolby 5.1 matrix system is the Shieber matrix system that failed the NQRC field trials. It is not Quadraphonic because it has only 2 simultaneous linear equations, thus it is a 4-2-4 system, 4 input signals, 2 transmission signals, 4 output signals. CD-4 is a discrete Quadraphonic 4-4-4 system, 4 input signals, 4 transmission signals, 4 output signals.

Today's 5.1, 6.1, and 7.1 amplifiers have discrete inputs for access to the individual amplifiers. This makes hookup very easy. Just make sure to turn off all of the speaker distance setup junk so the system is then really discrete!

Off the box,


Lou Dorren
CD-4 is a 4-4-4 system

 

[proufo]

Great!

Anyone here can create a logo?

 

[Cyber 1]

if Loudorren is interested in a logo I can create one, pm me if it is of interest.

 

[bangsezmax]

I am stoked that this is happening. Really looking forward to hearing this unit in my system.

Currently, my CD-4 rig is ATN-12s Shibata stylus > Signet/AT TK3E cart > SME 3009 tonearm > Thorens TD 125 MkII table > Sansui QRX-999 (recapped). I can coax some really nice CD-4 sounds out of that setup. The thought of hearing something better (or heck, something equal -- really good but sonically different) is a pretty exciting notion. And yeah, it's a wrinkle in time in the history of Quad. And I think that's really a cool thing to be a part of.

 

[wapfunz]

Wahooooooooooooooooooooooooo progress is wonderful. Looking forward ever more.

 

[quadjoe]

I'm so excited! I am so looking forward to hearing this new demodulator, and I'm going to be like a kid waiting for Christmas. Great news, Lou!

 

[The Quadfather]

I would like to know what the dimensions of the case are, and will this be the final dimensions, or rather is this the actual case that will be used? I am interested in rack mounting. Will rack mount brackets be availlable? It looks to be about 3 RU high, and about the right width unless the photo is misleading.
The Quadfather

 

[jrlinks]

Thank goodnes, no more turning a unit upside down and messing with a screwdriver on pots that will eventually wear and fail.
I have already bought 2 different test LPs for alignment on eBay.
Already have a "NOS" AT20SLa (SS stylus), AT14Sa, and a EPC450-II
So, I am ready.

 

[Q-Eight]

So, I'm guessing Carrier Signal Detection/Adjustment is automatic? (judging by the lack of adjustment pots)

 

[quattro64]

Quote// Not a complaint, I am just wondering if its possible to get different colored meters, such as with a green background or some other color. //Quote

I think it won't be long before we need to start a new thread "New CD4 Demodulator, MODDs!!!"

 

[jrlinks]

Not hearing anything from Lou about set-up discs being made for this
we assume that all buyers will have one already.
Or is it possible that the demodulator can somehow automatically adjust
for different sources and cartridges?

 

[jefe1]

A new set up disc would be nice but I don't think Lou has the ability to have new vinyl pressed. I think we're on our own in that regard.

 

[tektaff]

Great to see the progress so far.

For those of us that are too impatient to wait for the finished article, can we buy the boards (stuffed or unstuffed) and incorporate them into our own racks/systems?
Most of my system is composed of studio rejects, so i'd prefer to fit xlr's and set the gain to match pro gear, also i already have a RTW 5.1 channel meter which i can patch to, so i wont bother with meters on the box.

If this is a one off production run, will we get a service manual, or at least a set of schematics to be able to keep the thing running?