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Old 26th June 2010, 06:53 PM   #41
onis_uk is offline onis_uk  United Kingdom
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Join Date: Jul 2004
Location: uk
right arjen has sent me a delay board which cures the pop at turn on but stil i get the pop at power off !!!!!!! would putting a cap across the power supply help !?!?
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Old 26th June 2010, 07:48 PM   #42
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Location: South East. UK
Originally Posted by onis_uk View Post
right arjen has sent me a delay board which cures the pop at turn on but stil i get the pop at power off !!!!!!! would putting a cap across the power supply help !?!?
How did you manage to get Arjen to send a delay board, I could not even get a reply to my numerous emails sent to him!

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Old 27th June 2010, 09:42 AM   #43
teamacc is offline teamacc  Netherlands
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Join Date: Jan 2010
You can get rid of the power off pop by using a 230v relay.

You put this relay at the 230v line, when you power off the amp/buffer, the relay will open.

If you put this relay the way that, when it opens, the other relays on the board open too, your problem is solved.
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Old 4th July 2010, 01:15 PM   #44
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Originally Posted by borninthefifties View Post
How did you manage to get Arjen to send a delay board, I could not even get a reply to my numerous emails sent to him!


Me too, but I see now onis_uks reply with his concerns about the relay board.
Maybe Arjen will react when the issues are cleared up ...
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Old 7th July 2010, 02:35 PM   #45
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Send a message via MSN to ArjenShenzhen
Hi everyone,

anyone that has an issue with the MKII valve pre-amp can send me a mail at

Sometimes the mail is stopped by the Chinese fire wall, this is not something i can help. in this case please try or send me a message on MSN, this cannot fail.

i have now another 6 boards available, the new ones will come in soon also, should be enough to cover the ones that experiences problems.

I'm quite sure in most cases its a case of a poor performing power supply, so i suggest everyone to check this first.

since i want to keep everyone happy the boards are available at no extra cost.
for the ones that need it, please send your current address along in the mail.


Arjen Helder
Always check the power supply... and my spelling...
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Old 16th September 2010, 04:12 AM   #46
saudiof is offline saudiof  United States
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Join Date: Aug 2010
About volume control with the buffer. According to Arjen's store, the buffer pot should be used to set the distortion, and then the amp pot to set the volume. This seems strange as I dont want clipping! Isnt it best to use the standard approach of turning the amp pot all the way up (or better removing it), and then using the buffer/preamp pot to control volume? From my view, the only reason to have the amp pot in there is to slightly reduce the amp noise floor for very sensitive speakers.

I was thinking of wiring in one of the MV02 volume controls , either to the buffer input or removing the buffer pot and directly into that position. Anybody replace the buffer pot yet?
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Old 17th September 2010, 05:25 PM   #47
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I have been thinking about putting a buffer in front of each 2050 monoblock but don't know; Would you use only one channel(half) of a stereo buffer or would you y in and out of the tube buffer?

I have the first version buffers and they also pop on turn on&off but I just turn them on first and off last.
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Old 27th September 2010, 08:36 AM   #48
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Join Date: Sep 2010
Default Pops are gone

Hi there,

I have the Tube preamp MKII too, in combination with the TA2020 board and also found the switch on/off pops way too loud, also found 2 volts DC unacceptable for my speakers. Here is what I did to cure it (successfully):

signal flow:
input selector --> volume pot --> input tube preamp/input direct switch --> 10 seconds delayed relais --> TA2020 --> K4700 kit --> speakers

I might be a bit over protected, but works completely pop-less and with no switching hassle.

Here is it in more detail:
1) the inputs are switched with a relais board found on ebay (electronic salon)
2) the signal then goes thru the ALPS pot from Arjen
3) then the signal is fed into the tube preamp. I removed the B choice pot from the tube preamp and replaced it with good fixed resistors (voltage devider that lowers the voltage with 1/3). I also replaced the 2200 Mu cap with a 4700Mu cap on the board.
4) the output signal of the preamp is fed into a miniature relais to A, the direct signal is fed into B of the relais. The common of the relais goes to the TA2020 inputs.
This relais is time delayed with 10 seconds. That is approx. the time needed for the caps to level out the DC voltage at startup of the tube preamp. There is a switch at the front panel that powers the timed circuit of this relais, so I can choose between direct input and tube preamp input. As soon as I choose Tube input, The tube preamp is powered and after 10 seconds the mini relais switches from direct input to tube input.
5) the outputs from the TA 2020 goes trhough the velleman K4700 kit. I only use the time delayed circuit from the K4700 kit and leftout the DC protection circuit for now.

I will try to post some schematics and pictures (still in test modus :-) soon.
I am still burning in the tube, but the first listening sessions were very promising: wide soundscape and only minor hiss (barely audible at 2 meters from speakers, not audible at listening posistion in a complete silenced room).

Click the image to open in full size.

Happy soldering & take care!
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Old 27th September 2010, 09:53 AM   #49
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And here is the modified schematics for the tube preamp board and the delayed relais!
Click the image to open in full size.
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Old 5th October 2010, 05:16 AM   #50
gRF is offline gRF  Singapore
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Join Date: Jan 2010
Originally Posted by Zero One View Post
Hi Rich
The output caps are the large red ones, they can be removed if the buffer is feeding into a module that has input caps on it.
Should I replace buffer output caps with wire?
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