My ForePlay Processor Controlled Preamp - Page 3 - 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 13th October 2004, 05:06 AM   #21
ALBQ is offline ALBQ  United States
diyAudio Member
 
Join Date: Dec 2003
Location: Albuquerque
Default Check in

Algar,
Long time since I hear anything. Hope project is progressing. A quick question, have you tested your control circuit yet? Know you added a couple switches to the code I wrote and curious to know how its going.

Take care, ALBQ
  Reply With Quote
Old 13th October 2004, 12:08 PM   #22
Taco is offline Taco  Netherlands
diyAudio Member
 
Join Date: Nov 2002
Location: Place in the Netherlands
Very nice project, I missed your initial post ... I like your chasis .
  Reply With Quote
Old 29th November 2004, 03:21 AM   #23
diyAudio Member
 
Algar_emi's Avatar
 
Join Date: Oct 2002
Location: Canada, Qc
Hi everyone. I've working on that project part time. It is almost done now.
The switches are well integrated in the code. The code is almost completed. I'm still working to improve the volume motor control. I what a smooth, continuous operation. I'll post the code when completed.

I completed the analog assembly. Here the power distribution with the small control supply transformer. At the AC input there is an EMI filter with fuse integrated. The main supply goes to the main power switch and the control transformer. Then 2 relays control the filaments and HV in sequence at power up and power down.
Attached Images
File Type: jpg power distribution_small..jpg (86.4 KB, 725 views)
  Reply With Quote
Old 29th November 2004, 03:25 AM   #24
diyAudio Member
 
Algar_emi's Avatar
 
Join Date: Oct 2002
Location: Canada, Qc
GND is very important. Here the safety GND point. Directly connected to AC earth gnd it connect to both top and bottom metal covers. It connects also to the rear AC plate on a screw marked GND. Then it goes to a small junction point throught a gnd loop breaker, 10R, 3W resistor and a 0.1uF, 400V, X2 type in parallel.
Attached Images
File Type: jpg safety gnd_small.jpg (69.0 KB, 682 views)
  Reply With Quote
Old 29th November 2004, 03:30 AM   #25
diyAudio Member
 
Algar_emi's Avatar
 
Join Date: Oct 2002
Location: Canada, Qc
Then all the GND inside the preamp connect at one point only, the star gnd on the left. This this point connects directly to earth gnd throught the GND loop breaker. The GND are all run separately:
HV and Filament supplies power GND, right and left audio channels, audio gnd of the jacks on the back.

That note that the digital gnd is not connected anywhere to the preamp gnd. The digital section runs on a completly separate supply.
Attached Images
File Type: jpg star gnd connected to safety gnd_small.jpg (67.4 KB, 671 views)
  Reply With Quote
Old 29th November 2004, 03:34 AM   #26
diyAudio Member
 
Algar_emi's Avatar
 
Join Date: Oct 2002
Location: Canada, Qc
Both supplies use MUR860 soft recovery diodes with caps snubber. I used WIMA MKP small caps on the filament and X2 HV type on the HV section. Everything is point to point. I'm using lacque coated good grade copper wire. This wire is the same used to rewire motor for greater efficiency. It is hi conductance copper from a electric motor shop.

The filament rectifier bridge is on the front, the HV is on the back. The power transformer sits just under the bridges.
Attached Images
File Type: jpg both bridges_small.jpg (71.3 KB, 587 views)
  Reply With Quote
Old 29th November 2004, 03:37 AM   #27
diyAudio Member
 
Algar_emi's Avatar
 
Join Date: Oct 2002
Location: Canada, Qc
This is the HV filter section. I'm using a three section PI filter, with 330uF, 400V and 1K resistors. A 120K bleed resistor is at the end with a ERO KP1832 bypass cap that I had in stock (check on the left). Check my "wood vibration absorber' for the caps

The nice power resistors are from a surplus store. Not needed but nice
Attached Images
File Type: jpg hv supply pi filter_small.jpg (51.6 KB, 599 views)
  Reply With Quote
Old 29th November 2004, 03:40 AM   #28
diyAudio Member
 
Algar_emi's Avatar
 
Join Date: Oct 2002
Location: Canada, Qc
The filament filter with the two 3300uF caps well mounted on the metal frame. I added an ERO MKC1863 1.5Uf as bypass cap.

The power transfo used Hammond 269AX, can provide enough current to supply 6N1P tubes, 6.3V, 2A

You can also see the base of the releays mounting plate.
Attached Images
File Type: jpg filament supply_small.jpg (61.2 KB, 507 views)
  Reply With Quote
Old 29th November 2004, 03:48 AM   #29
diyAudio Member
 
Algar_emi's Avatar
 
Join Date: Oct 2002
Location: Canada, Qc
This is a complete channel. Missing are the wires from the volume pot and the output coupling cap. I will use a NOS paper in oil from Sprague. I'll do some listening, and I may use a bypass with an ERO KP1832 cap.

Check the power distribution with the nice wires, gnd, filament and HV supply. I used massive bypass on the 470uF, Panasonic decoupling cap on the cathode resistor. Electrolytic cap at this location are reported to add to the sound. The bypass are a try to improve on that, Still need to listen to it. I used what I had in stock, 2.5uF Cornell Dubiller poly cap and 0.047uF ERO KP1832.
Check on the left of the socket.

I also added ferrites on the filament wire to reduce radio induction if possible, check the two small beads on the wire.
That is all for now.
Attached Images
File Type: jpg one channel_small..jpg (73.7 KB, 526 views)
  Reply With Quote
Old 5th December 2004, 09:37 PM   #30
diyAudio Member
 
Algar_emi's Avatar
 
Join Date: Oct 2002
Location: Canada, Qc
Here, I just completed the front panel.
Attached Images
File Type: jpg preamp_front_small.jpg (46.7 KB, 570 views)
  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
Digitally controlled analog Input/Output stereo audio processor tolaemon Chip Amps 3 17th January 2011 10:08 AM
Foreplay Preamp volume popping arc2v Tubes / Valves 7 22nd August 2007 04:04 AM
Preamp: Foreplay or 5687 or 12B4 Toyman_PA Tubes / Valves 24 4th August 2004 05:10 PM
Pics of Foreplay Preamp TubeHound Tubes / Valves 16 5th February 2003 02:29 PM
Tube preamp similar to Foreplay JAZZ2250 Tubes / Valves 6 10th December 2002 11:14 PM


New To Site? Need Help?

All times are GMT. The time now is 11:10 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