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MDAC First Listen (part XXVIII)

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JohnW said:
Hi David,
On MDAC2 we have also used a higher quality type Relay (Hopefully reducing one of the original designs weakness).
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Why not place the mute relay in a shunt position instead of in the signal path ?
At least the output signal doesn't have to feed through relay contacts.
 
We need to route the AV bypass to the RCA / XLR outputs when the MDAC2 is powered off - also the new output stage can dump some serious current while energy remains stored up in the bulk caps... it would weld the relay contacts in no time...

I'm just trying to get my head around how I can take the feedback after the relay (thus including the relay contacts in the feedback loop) the output stage has over 200dB of feedback at DC, 120dB at 20KHz... so it would be nice to put this 'Correction" power to good use - there are many output combinations (XLR, RCA, Balanced headphones and 6.3mm headphones)... my heads a little scrambled ATM - once I've a solution on paper its the last part of the PCB layout to complete so I can issue the analogue stage prototype PCB.
 
Analogue stage pcb, that makes things sound inexorably close John.

I can't wait to hear the new output stage.
 
I'm sure it will pay off John. A little tweak here, an improvement there, it all adds up.

It would be fair to say I'm pretty damn excited by the prospect of improved sound once again. I'm buying a new bike tomorrow and I'm actually more excited about the Mdac2 than I am that. and I love my bikes.
 
JW, Ian, Tony, Phil - just wanted to say many thanks for your advice on power amps, very much appreciated. Also Thanks JW for offering to upgrade a Quad for me. It really is a very kind offer but I can't use your valuable time whilst we're eagerly awaiting the Lakewest products, it wouldn't be fair.

I've been in contact with the guy selling the Parasound Halo A21. Sounds very promising plus he only lives 30 miles away so I can actually test it. According to a review I read it has gain controls on the back. Does this mean I have a better chance of matching to the sweet spot on the mdac without using attenuators, or just another process in the signal path to detract from the sq?

Also, the 3 pin XLRs for the balanced outs are the same connectors on microphone leads right? I have bog standard mic leads in my loft, can I use these? Are higher quality XLRs of the same importance as higher quality RCAs, or less or more important?
 
m-il said:
JohnW or Dominic,
I know it's a bit OT (sorry for that) but I thought that it will be fastest way to get reply (since "audiolab at last..." thread is almost dead). What are the latest software version for old lcd 8200cdq units (control/servo/mainboard software)?
Thanks in advance,
Emil.
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Emil,

I believe V1.6 for LCD (V2.0 for OLED units IIRC). If you have V1.6 then the Servo and Mainboard will also have been upgraded to the relevant version.
 
therixonator said:
JW, Ian, Tony, Phil - just wanted to say many thanks for your advice on power amps, very much appreciated. Also Thanks JW for offering to upgrade a Quad for me. It really is a very kind offer but I can't use your valuable time whilst we're eagerly awaiting the Lakewest products, it wouldn't be fair.

I've been in contact with the guy selling the Parasound Halo A21. Sounds very promising plus he only lives 30 miles away so I can actually test it. According to a review I read it has gain controls on the back. Does this mean I have a better chance of matching to the sweet spot on the mdac without using attenuators, or just another process in the signal path to detract from the sq?

Also, the 3 pin XLRs for the balanced outs are the same connectors on microphone leads right? I have bog standard mic leads in my loft, can I use these? Are higher quality XLRs of the same importance as higher quality RCAs, or less or more important?
Click to expand...

Yes, you can thank Tony for the good find :)

The gain controls built in the amplifier should cause little degradation.

Microphone XLRs are pretty poor quality, designed to be flexible rather then high quality, might be worth begging to borrow a pair of short XLR's from your local dealer :)

I'm sure your going to be impressed with your Amp... John Curls a very good designer - rumour has it that "John's" make some of the better HiFi designers :p
 
Just a note on the MDAC2 Headphone outputs - due to PCB space restrictions, the front headphone Jack will also enable the rear 4W Balanced XLR output.

We can also enable a Long press on say the Remote control Mute button to select the Headphone output (as the rear panel Balanced XLR headphone output is not easily accessible).

I hope this will be OK for Everyone?
 
JohnW said:
Microphone XLRs are pretty poor quality, designed to be flexible rather then high quality, might be worth begging to borrow a pair of short XLR's from your local dealer :)
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Unless it's already a very good quality and flexible microphone cable from Mogami, Canare, Belden using Neutrik or Switchcraft connectors, in which case I'd be avoiding your 'audiophile' dealer like the plague ;)

Peter
 
Igloo Audio said:
Unless it's already a very good quality and flexible microphone cable from Mogami, Canare, Belden using Neutrik or Switchcraft connectors, in which case I'd be avoiding your 'audiophile' dealer like the plague ;)

Peter
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I'd not be so quick to judge, the cheap microphone XLR cables I've seen use some "Horrid" but certainly not pure Copper - not even close... decent quality cables need not cost much - I'd worry more about the Cable then the connectors - certainly some of the Switchcraft connectors are sourced from "catalogue" items in China (luckily there are a few High quality connector vendors in China if you know where to source) ...
 
misterdog said:
John I already have 5 'spare' cases. I have emailed Audilab requesting a front panel to no avail.

Any possibility from your end ?

Sheffield needs 3 :):)
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You would need front panels, and internal PSU PCB + the AC adaptor & Remote handset etc... So its not simply the "Front Panel"

I have one spare black front panel - I'd like to keep as a spare part just in case... Sadly the cheapest route to sourcing the parts is as salvaged units...

Sorry Sheffield :(

Maybe further down the road we will release our own designed Front panels etc... but ATM we will be kept busy just upgrading existing MDACs :)
 
JohnW said:
I'd not be so quick to judge, the cheap microphone XLR cables I've seen use some "Horrid" but certainly not pure Copper - not even close... decent quality cables need not cost much - I'd worry more about the Cable then the connectors - certainly some of the Switchcraft connectors are sourced from "catalogue" items in China...
Click to expand...

Avoid very cheap poorly made cables for sure but, lots of the major brand audiophile cables sold today are using the names I mentioned, they're just being re-wrapped. You know this... or at least should know this :confused:

Peter
 
JohnW said:
Yes - Digital Pre-amplifier, with the later FPGA firmware builds (Later software) improving upon the ESS own internal Digital volume control.
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Will the ESS internal volume control be bypassed completely with FPGA?

If yes, would it be possible to have volume control applied to MDAC2 digital output, as an option?
 
Maybe true for more then a few, I try to avoid the darker side of this industry.

While at Cambridge Audio we sourced specially designed cables from Asia - and I'm also in discussions with Chord exploring the possibility of custom interface Cable - As far as I'm aware atleast the type of cable I've requested from Chord as a sample is manufactured for them - but whose to say for sure, maybe its indeed a standard "catalogue" item... but I've not encountered it... yet...
 
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