New DISPRE preamp, successor to previous popular version

[jhsmith123]

I'm also interested in getting board.
thanks.

 

[PMA]

To everyone interested, please send me an e-mail.

However, with some e-mails I have troubles to reply, I get the replies back refused by recipient's server. I will try contact through DIYaudio mail button in these cases.

 

[kestrel200]

Any news on when you might be ready to ship these?

thx

 

[PMA]

The boards are already produced, and I am subsequently responding to the requests and sending the boards. In a few days you will have a reply. Anyway, I have problems with some of the e-mail addresses, especially hotmail.com, my mails are refused and returned from these addresses.

 

[kestrel200]

Great! I'm looking forward to hearing from you and getting the boards. How and when do you want payment? Do yiu want us to order them from your website?


mike

 

[Tarasque]

PMA, I am interested in a PCB as well. Hopefully your return mail will make it to my inbox.

 

[PMA]

Hello all,

Thanks everyone for your interest in the PCBs. The actual round is finished, and all the PCBs produced are sold or dedicated to customers.

This time I have had many troubles with many e-mail addresses, I do not know why, maybe a security reason and setting of some servers. I try to reply every e-mail I receive. I tried to continue in communication with several of yours through diyaudio mail button, but it is quite time consuming and ineffective.

There might be some next round in future, but not immediately and not very soon. The problem is that when I manage this board sale and shipment I have no time for any circuit development and tests, and it is unacceptable.

Thank you for your patience, orders of many of yours were satisfied and I hope the others would forgive me.

Yours,
Pavel

 

[kestrel200]

Pavel,

I recieved the board and it looks great. Do you have any of the power supply boards left?

 

[PMA]

At the moment I have no Dispre 2 PCB and no power supply PCB. I will start new production later (in 1 - 2 months), I need my time for further developments and evaluations; distribution and agenda is quite time consuming

 

[PMA]

PCBs, and assembled soldered modules as a new option, will be now available. For more info, please visit my webpage, follow Dispre II article and Pricelist. All communication through e-mail, please.

 

[kestrel200]

so the power supply PCB is available now?

 

[PMA]

I hope the mods to make appropriate action, the documentation is not for free distribution, and is covered by copyright law.

 

[PMA]

Bob Cordell sometimes speak about HF THD measurements, like THD30. I have decided to measure the Dispre 2 at 100kHz. However, it is not so easy to get enough resolution. First I would like to show measurement of generator itself at 100kHz:

 

[PMA]

Now the result at Dispre 2 output. The load is 75 ohm Dispre output resitor + 50 ohm input impedance of spectrum analyzer. That means, we have 2.7Vp-p at Dispre output into 125 ohm load:

 

[PMA]

Thanks.

 

[Rafael L]

Hi

Because the use of cables Silver/teflon, is used in wiring internal preamp?
for short cables makes a difference, that standard copper/pvc?

 

[PMA]

I do not think it makes difference for a very short cable. I would suggest just good shielding.

Anyway, there are other guys who know about cables much more than me

 

[PMA]

Schematics and assembly drawing now released for personal, non-commercial purposes. Please visit my webpage.

 

[Rafael L]

I do not think it makes difference for a very short cable. I would suggest just good shielding.

Anyway, there are other guys who know about cables much more than me

I also think it makes no difference for short cables, more cables for connection is useful, the position of the pot on your preamp will need a cable low capacitance, between the source signal and the input preamp.

Interesting to use of BC557/547, had good results with these TR's
The majority of other people would use the BC550/560 low noise.
I note your suggestion to TR's for amplification of signals
Because you do not include control of tone? Its enclosure is acoustically treated. You have panels to avoid reflection in room?

Schematics and assembly drawing now released for personal, non-commercial purposes.

Wise decision, if you do not want commercial copies not publish the draft pcb (negative)...

 

[PMA]

Full scale (25Vp-p) 100kHz square response, with 1k + 220pF input RFI filter connected.