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MDAC First Listen (part 00100011)

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Chris,

I'm going to take a "Big Leap" with the Slave units and have made contact with a vendor in China - we are in discussions to customise casework for MDAC2 Slave units, TDAC amongst other projects.

I have an "off the shelf" sample of there existing case to confirm construction, build, feel, finish and cosmetic quality - there are some small issues as to be expected but I believe we can work with them.

The Slave units are an easier first step as I don't need to worry about the front panel / user controls OLED display (with its display window) etc. From experience, it takes much time and effort to make buttons / user controls feel and work well.

I don't expect that the quality will be 100% perfect so we will order and extra 10% units so we can "Mix and match" the best parts as we build up the chassis - and reject any damaged / ill fitting parts - its the only way I can see to deal with ordering mechanical parts from China. I hope an extra 10% will satisfy requirements.

The Full size chassis will include HQ internal PSU - and a remote handset is not required so no need for a MDAC Donor unit for the slave devices.

Target price for the the HQ Chassis with internal PSU is GBP200 to GBP250, maybe less its still early days - I think its far to say closer to GBP200 then 250 (as the slave units don't have a complex front panel).

At a later date once we have worked through the complexities of the mechanical chassis and QC issue we can offer matching "retrofitable" full size cases for the Master MDAC with internal HQ PSU etc. - so you can then sell on your MDAC1.... But TDAC comes first.

For the donor less "Master MDAC2" The Remote handset is an issue as I will need to order 1K pcs... maybe everyone gets a couple of spare handsets :D IIRC the current handset cost about US$2 China FOB.

When ordered with a Master MDAC, Slave L2 MDAC are GBP300 development cost + "PCB at Cost" so a GBP100 saving (L2 for L1 development cost). L2 PCB's are required for the slave units as the "L2 's Advance clock option" is required to insure all ASRC channels are kept in sync - Oh and stupid me, we also require the L2 DSP option :D
 
John

How much will the VFET amps cost.

Mike I just ordered some more VFETs for a friend here on PFM, so I will have a few extra sets.

The VFET project is a Reference design - its me as a designer "showing off" and having some fun :) It will be the best Analogue amplifier I can design using the best available components past a present:-

Paralleled Mini Tube Font end for low noise and distortion (and High RF noise immunity).

Fully balanced design (Bridged output stage) so the amplifier is not referenced to the Ground connection - facilitating the highest Dynamic range and lowest THD.

VFET ClassA output stage "Current dumped" by the very best but sadly now discontinued Hitachi MOSFETs in a non switching error corrected "power stage".

It might sound all rather cryptic - but will offer a truly unique design using the very best of legacy and present day components. Output power is 200W to 250W per channel via balanced input, needlass to says its a true Balanced design.

The Mono Blocks will also communicate with the MDAC2 offering on-board Gain scaling thereby offer the industries highest "system" dynamic range.

Each Mono Block will have a Plasma tube Bargraph display, which can be selected to display Output power, Output current, Uncorrected signal error (in parts per million) & operating temperature, it can also be completely switched of :)

The Bargraph Plasma tube is simply for fun but its useful to see the Current demands of your speakers + see the amplifiers "uncorrected signal error" ie THD - which SHOULD just endup hovering around zero unless driving something REALLY horrid or using the amplifiers as Ark Welders :D

Each pair of Mono Blocks is hand built - only 20 pairs will be built (I will be keeping a couple of pairs for my own reference system).

Price is GBP3.5K a pair with lifetime warranty - but you will have to wait until the MDAC2 is heading towards production before I can start building the units.
 
it's not exactly clear whether there's going to be a "lite" version of the VFET amp. Any insight welcome. :)

Well I will design a "Cheaper" power amplifier but sadly it will not use the "triode like" VFETs as they are in extremely limited supply - they where last manufacture in the early 80's - I've spent a few thousand dollars securing the last of the devices.

Realistically, I don't see the MIMP / MAMP released until 2016... 2015 will be spent supporting MDAC2 production and upgrading units, VFET and TDAC etc.
 
Hi JohnW where do I sign up for s VFET smp ;).

3.5 is a lot of money, but a more than fair price for such an amp if you ask me ( and less than my mc275 costed actual )

Hope Ill be lucky enough to grap a set of those wonders ;)
 
Hi JohnW where do I sign up for s VFET smp ;).

3.5 is a lot of money, but a more than fair price for such an amp if you ask me ( and less than my mc275 costed actual )

Hope Ill be lucky enough to grap a set of those wonders ;)

Reenberg,

I'll put your name on the list pending the safe arrive of the extra VFETs :)

Last week I ordered extra pairs of VFETs - once I have these safely in my hands then I know its safe to request your first stage payment :)

The decision to design a fully differential amplifier (bridged) effectively double the number of VFETs required per unit (2 pairs per Mono Block), this eat up my reserve stock - I even had to give up the VFETs reserved for my own amps to meet the existing order requirements. I'm just as keen to see the extra VFETs arrive :)

It would be ironic if I ended up without a pair of VFET Amps for myself :rolleyes: :( :p
 
John - You HAVE to have a set for yourself!!!! No questions asked! Take the VFETs you reserved for me as I was being indecisive and use those for your own amp if you must.

Just paid up first 3 installments for my second MDac2... But forgot to put my username down. One is going to be fully spec'd and the other is going to be a plain L2.

Thanks,
Sam
 
Hi Sam,

Funds arrived - thank you.

Renata and I where just wondering why you paid a second time around :) - is this for a slave unit in full size chassis or a standard MDAC1 to MDAC2 upgrade?
 
Standard MDac2 upgrade. I run 2 MDacs, one in living room main system and one in the study for the PC (running into a DIY LM4780 chipamp driving a pair of Dali Lektor 1s or headphones when I want to be loud without waking anyone).

:)

The main living room one I am planning a full blown fusion L3 spec with any/all the extras..

Thanks again,
 
Standard MDac2 upgrade. I run 2 MDacs, one in living room main system and one in the study for the PC (running into a DIY LM4780 chipamp driving a pair of Dali Lektor 1s or headphones when I want to be loud without waking anyone).

:)

The main living room one I am planning a full blown fusion L3 spec with any/all the extras..

Thanks again,

Hi Sam,

OK great (thank you) - as its your second MDAC2 you can have this second unit as L2 for L1 development funding saving you GBP100 (but you would still pay for an L2 PCB "at cost") - then you can play around with slaving your two units :)
 
Can I pay the three slaves using the combined installment option?

Yes, or shall we just send you a PayPal invoice for all 3 units (not sure if this save you anything)? - if it does not save on PayPal charges then you might as will just pay x3...
 
Yes, TDAC has to be full size and that's why I'd like to use the same chassis for the MDAC2 slaves...

Do you have a plan (or an option) to include CD player in full size TDAC chassis?

Basically, VFET amp owners will get the option to purchase a TDAC "At Cost" to compensate for the project delay, I'm not sure how much can be salvaged from the MDAC2 - but TDAC "build costs" will be affordable, maybe around GBP500 - GBP600, the "Solid aluminium chassis" will eat at a significant chunk.

What is estimated price for TDAC including development costs?
 
Hi John,
I wouldn't want to deprive you of course, but if you do have extra vfet's arriving could you put me down for a pair as well? my curiosity has finally got the better of me!
Chris
 
John
At some stage I guess you will need to have a new list of people who want the TDAC as I suspect some of those on the original list will now be content with the MDAC2. So this is me confirming I want a TDAC please :)
Ian
 
Hi John,
I wouldn't want to deprive you of course, but if you do have extra vfet's arriving could you put me down for a pair as well? my curiosity has finally got the better of me!
Chris

Chris,

I don't know what I've been smoking, but I have enough VFETs available to build 14 pairs with more on there way :)

I don't understand how I miscounted, but its a pleasant surprise to discover I have more VFETs then I original thought.

The only "possible" major change to the project is that I might build the Amps into there own custom solid CNC Milled aluminium chassis rather then salvaging 8200MBs - I have a sample chassis being shipped from China.

For the following reasons:-

1. Following the design decision to go for a symmetrical bridged design, I need double the number of output devices / VFETS - and thus ideally a larger Heat Sink / Chassis - the new Mono Block chassis will also better match the TDAC / and later the MDAC2 HQ chassis.

2. The quality of the 8200MB chassis does not do justice to such a statement design - while the solid milled Chassis are costly, they are of far higher quality and will have the Lakewest / VFET laser milled Logo etc.

I'll make the final decision once I receive the sample Chassis - and I also need to have approval from the other VFET "members" that this proposed change is OK.

There will be no extra cost - I'll recoup the difference by reselling the 8200MB donor units I've already bought, its a big change but one that would be for the better.

As I say, I first have to confirm the quality of the new chassis (and have approval from the other members) - however the sample MDAC slave / TDAC chassis from the same vendor looks very promising.

If the sample is not up to Spec. then I'll stay with the original 8200MB which would save me trying to off load the 8200MB donor units I've already bought for the project! (but I prefer the new Chassis for the above reasons).
 
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