flexy -a multirole driver/preamp- - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 30th November 2010, 01:47 AM   #1
Gluca is offline Gluca  Italy
diyAudio Member
 
Gluca's Avatar
 
Join Date: Nov 2004
Location: Back to Italy
Default flexy -a multirole driver/preamp-

Folks

I am about to start a new project and as I need to experiment with many configurations I ended up with an idea for a flexible PCB that allows to switch among them by means of jumpers. So in a matter of minutes the PCB will allow to build a very different preamp or driver. The project will use noval dual triodes and can be set up as

1) SE+SE (two channels)
Click the image to open in full size.

2) SE+CF (one channel ... ie two PCBs)
Click the image to open in full size.

3) SE+splitter (one channel ... ie two PCBs)
Click the image to open in full size.

4) SRPP (with active load ... one channel per PCB)
Click the image to open in full size.

5) LTP (one channel per PCB)
Click the image to open in full size.

CCSs and LEDs are used to bias the tube. I drafted also a PCB for the CCS, the now classical supertex cascoded DN2540s, that can be installed directly onto the main PCB or used for other projects

Click the image to open in full size.

Click the image to open in full size.

If there is enough interest I can try to run a batch of PCBs. Target costs for bare PCBs might be

20$ for the main PCB
5$ for the CCS


I am also working on a ladder stereo attenuator as I could find none online (well ... there is a superexpensive 41 steps made in Japan ... and a supercheap 24 steps made in china). I spotted a nice switch made by palazzo that seams to fit perfectly onto the idea. Link to the switch

And here it is the prototype I am assembling that should not look much different from the final one.
Click the image to open in full size.

I drafted a PCB for the ladder attenuator and Palazzo switch with 1206 SMD resistors: they fit perfectly between the switches' pins. I am waiting for a quote for the assembled PCBs but I believe it should be in the 80$ ballpark: the switch itself costs 40$. Now, 80$ is much more than a pot but much less than big brands switched attenuators and this is a ladder attenuator not a shunt attenuator so I am using 2x resistors.
Click the image to open in full size.

The switch is not-shorting but I contacted Palazzo and they are ready to make it shorting if there is a "big enough order".

All that being said, having a proto board made just for me or a small batch will not be very different pricewise but I believe the idea might be useful. What I really need is the ladder attenuator but they are not assembling the shorting switch just for a couple of pieces ...

Let me know. I have very small free time for this hobby but hopefully I can finalize the idea during the XMas holidays ... sob

Gianluca
  Reply With Quote
Old 30th November 2010, 02:22 AM   #2
diyAudio Member
 
aardvarkash10's Avatar
 
Join Date: Mar 2007
Location: Auckland, NZ
cool! I'd be in for some of the CCS boards - say, 6?
__________________
"Folks, you can't prove truthiness with information. You prove truthiness with more truthiness. In a process known as truthinessiness." - Stephen Colbert, The Colbert Report
  Reply With Quote
Old 30th November 2010, 03:26 AM   #3
syyma is offline syyma  United States
diyAudio Member
 
Join Date: Apr 2008
Location: SF Bayarea
Default CCS Board

I'm interested in the CCS board. Count me for 4 please.
  Reply With Quote
Old 30th November 2010, 05:26 PM   #4
Gluca is offline Gluca  Italy
diyAudio Member
 
Gluca's Avatar
 
Join Date: Nov 2004
Location: Back to Italy
I received a quote from the PCB maker: the ladder attenuator PCB should cost each 20$ and we have to supply resistors. Final cost (PCB+resistors+switch) is then 70$ or so. It depends on how many of them we are going to order.
  Reply With Quote
Old 1st December 2010, 02:39 AM   #5
diyAudio Member
 
Join Date: Apr 2003
Location: Southern Tier NY
I am interested. Is 70$ for the assembled ladder attenuator?
__________________
Living Life Doing the Waltz in 4/4 meter.
  Reply With Quote
Old 1st December 2010, 03:29 AM   #6
Gluca is offline Gluca  Italy
diyAudio Member
 
Gluca's Avatar
 
Join Date: Nov 2004
Location: Back to Italy
Quote:
Originally Posted by SGregory View Post
I am interested. Is 70$ for the assembled ladder attenuator?
Yes, that is the best estimate for the time being: I will be more precise when I have a better idea of the final number of buyers. Most probably the switch will NOT be soldered onto the PCB but all the SMD resistors will be for sure.

Chip resistors by dale

Digi-Key - 541-1.00FFCT-ND (Manufacturer - CRCW12061R00FKEA)
  Reply With Quote
Old 4th December 2010, 10:23 PM   #7
Tfan69 is offline Tfan69  Italy
diyAudio Member
 
Tfan69's Avatar
 
Join Date: May 2009
i'm in for the attenuator (insomma.. ce sto )
  Reply With Quote
Old 5th December 2010, 03:31 AM   #8
Gluca is offline Gluca  Italy
diyAudio Member
 
Gluca's Avatar
 
Join Date: Nov 2004
Location: Back to Italy
Group buy ongoing. Most probably I want use SMD resitors but small 1/8 or 1/4 W through hole resistors

I added a couple pics of the work in progress in the GB discussion.

24 steps ladder attenuator 50k stereo
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
My Flexy Rack Saint Everything Else 5 30th June 2004 03:30 PM
Done with rough construction of TNT Flexy rack Tiggerfip Multi-Way 4 1st March 2004 05:02 AM
line driver/preamp offroadbum Car Audio 7 21st February 2004 07:53 AM
flexy cross; a new diy rack rwagter Everything Else 10 29th May 2003 08:47 AM


New To Site? Need Help?

All times are GMT. The time now is 11:16 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2