[poty]

Hello,
I'm trying to build combined Piccolo and Cornet2 in one chassis (with external power supply) and my own board layout with some added functionalities (needed, according to the discussions on the forum, maybe only for me).
It's great that there are schemas and very good discussions about the DIY products. But, as a foreighn country DIYer (Russians) I it seems do not understand several hundred things.
About Piccolo. There are several ... parts reffered in the scheme as 2SK389. The google says it is transistors, but in the schema they are marked as tubes. Could somebody help me with understanding this?
Then... I tried to search for supply of the items (2SK389), but all I've found is Toshiba'a (mostly) transistors which lookes very differently from surface mounted parts used in the original DIY kit layout. Could somebody, who owns the kit, look at the original board and say what is really the part is?
Just as a thought. I think it is good thing to have 0 dB gain possible with the Piccolo. But there is a choice: 0db vs. power off. Is it a matter of reduced price for power supply switch?

[analog97]

Hello:

1.  The 2SK389 are already pre-installed by Hagerman Labs when you buy the 1/2 kit.  They are JFET's.
2.   The Piccolo is designed as a MC head amp.  Therefore, no 0 db gain was designed.  If you don't need any gain, there are other options for loading that are less expensive.

Good luck with the Piccolo as it is superb!!

[poty]

1.  The 2SK389 are already pre-installed by Hagerman Labs when you buy the 1/2 kit.  They are JFET's.

The question was different. I'd like to have my design of PCB, the chassis, some changes in the scheme and so on. So I don't want to buy the the 1/2 kit. 2SK389 has different look than the one used in the 1/2 kit.

2.   The Piccolo is designed as a MC head amp.  Therefore, no 0 db gain was designed.  If you don't need any gain, there are other options for loading that are less expensive.

There are many ways you need the 0 dB. For example, if I often change my cartridge (MC-MM) and do not want to change connections or I want to support the high output MC cartridge... More than that - the PCB is somehow designed to have the 0 dB. The question is - why it is designed in such a way that you have to choose between the 0 dB and the power off?

[analog97]

Sorry, but it would be innappropriate for me to comment further as I don't have the skill level to build the Cornet2/Piccolo without buying the Hagerman PCB's.  All I can see is a box filled with a thousand wires and lots of hum and problems.

Good luck and let us know how it turns out.     

[tketcham]

Hi, poty,

The power off is standard on the Piccolo so that you can turn off the battery pack if you're using the battery power supply instead of the AC adapter. I decided to have 0 dB gain with my Piccolo so I disconnected the battery pack and use the AC adapter.

Tom

[hagtech]

Yes, there is a 0dB option.  I think it is in the manual.  You jumper the power switch such that it is always on.  The "OFF" position then becomes "0dB".  I did this for exactly the reasons poty states.

And I am using the LSK389, a SOT-8 version of the dual matched JFETs.  I did the ARCHIVER (http://www.hagtech.com/archiver.html) using the obsolete 2SK389 parts  They have a much better package and designed for optimal layout. 

jh

[poty]

Yes, there is a 0dB option.  I think it is in the manual.  You jumper the power switch such that it is always on.  The "OFF" position then becomes "0dB".  I did this for exactly the reasons poty states.

It was only thoughts... I think about the possibility to add one more "click" to the switch to have both 0dB and OFF option. Or have power switch.

And I am using the LSK389, a SOT-8 version of the dual matched JFETs.  I did the ARCHIVER (http://www.hagtech.com/archiver.html) using the obsolete 2SK389 parts  They have a much better package and designed for optimal layout. 

Thank you very much for the answer! Great! Now I could go further I think.
The only question left is how to match the scheme image of the JFETs (pictured like tubes in cathode, grid, anode terms) with actual Gate, source, drain terms of JFETs.

[tubesforever]

It would be pretty simple to add a switch for power on and off. 

The PCB only allows for a 4 position switch.  I think I will modify mine for zero output.  Its a very simple process. 

There are a great number of papers substantiating that you will have lower noise and distortion using a multilayer circuit board for low level signals.  I would stick with the board for that reason alone.  The signal and ground plane are within hundredths of an inch. 

Jim's boards are about the best constructed, quietest performing pieces I have even encountered.  My Piccolo is the quietest head amp I have ever heard at any price.  It's so quiet, its actually quieter than my SUT's. 

Look for the Black Gate FK electrolytics for your build.  Their noise level is -160 db.  Also, make sure to push the DC offset device to the high frequency setting.  It makes a noticeable difference in my system. 

Jim you should list this in your manual.  It did not appear in mine but luckily I learned about it here. 

Cheers! 

[poty]

Also, make sure to push the DC offset device to the high frequency setting.  It makes a noticeable difference in my system. 

What do you mean? What is the DC offset device? "DC" and "high frequency" together sounds rather strange for me...

[tubesforever]

The TC7662BCPA increases DC voltage from 1.5v to 15v with two inexpensive resistors.  It eliminates the need to provide transformers which would place a higher EMI near the low level signals.  This device operates at 10khz and I could hear this tone when using a Denon DL103R on the highest gain setting. 

You can force the device to operate at 35khz, so the tone will be above the audible level of human hearing.

Simply jumper pin 1 to 8 and you get 35khz operation.  No need to be concerned about the device.  If you push up the frequency, it will produce a head amp that can be as quiet or quieter than an SUT. 

Cheers!

[poty]

Thank you very much TubesForever! It's a great idea! Very simple and effective! I like the Hagerman's schematic more and more!

[poty]

As soon as I started to post my questions about Piccolo here, I'll post another bunch of them:

When drawing the layout of my version of PCB for universal MC/MM phonostage I thought about the two rotary switches (for gain and for loading) used in the Piccolo. Why they should get into my mind? The problem here was - I'd like to get both Piccolo and Cornet in one box (the power supplies for both of them - in another), so I have to choose for what device I prefer to shorten the outside connections. Of course I chose the lowest signal device of the two - Piccolo. It seemed the Piccolo's best place is around the back side of the box (then I could use RCA soldered right into the PCB), but then - there are the rotary switches. If I borrow the Hagerman's design I'll have to use some kind of extenders from the actuators of the switches to the front panel's knobs (meanwhile - do you know where to get them and their right names in English?). But I thought about using relays instead of the switches too. The question was - what relay is suitable for such small currents and voltages?
To get an estimated specs for that type of circuits I look through the specification of the switches and... I found, that the application for the types of the contacts used in Piccolo is - power. For low level/dry circuit there should be B or G type of contacts instead of Q. So I think the Piccolo could be improved in some way and to some degree just with changing the switches.
But... It leaves the question open: what relays are suitable for this type of application? Maybe someone uses some relays in such circuits and know part numbers or manufacturers or where to ask that?

[poty]

More questions about Piccol design!
I think about adding some more fixed values to the LOAD and GAIN circuits of the Piccolo. In the LOAD field - there is no problems. But what about the GAIN resistor values? I tried to estimate something from the schema, but the resulting counted values is not the same as in the stock version. Maybe there is a simply way of counting the resistor value for a gain value?

[hagtech]

You can always put the rotary switches on the back.  They are not used often - usually just set once each time you change cartridges.

I used to have a plot of gain versus resistor.  Can't find it now.  It's pretty much a straight line on log scale until about 20dB, then curves over to a maximum of about 26dB.

jh