ive build an amp now using an arjen helder ta2020 mk3 board and a mk2 valve preamp ! i have also fitted a small relay board which he sent me to cut the speaker wires to "cure" the on off pops!!
it cures the power on pop but not the power off thud i get!?!?
i have attached a small pic to show what i mean but if i disconnect the buffer amp signal i get no power off thud !!!!!! so this tells me the pop is being generated from the preamp, so now how do i cure this problem?!?!?!? its rather annoying not to mention its damaging my speakers
cheers Dom
it cures the power on pop but not the power off thud i get!?!?
i have attached a small pic to show what i mean but if i disconnect the buffer amp signal i get no power off thud !!!!!! so this tells me the pop is being generated from the preamp, so now how do i cure this problem?!?!?!? its rather annoying not to mention its damaging my speakers
cheers Dom
An externally hosted image should be here but it was not working when we last tested it.
the relay at the speaker cable should also be interrupted on 230v drop. (power off)
So: if you reroute the relay route, with a 230v relay in between, and put this after the on/off switch, and make sure there are enough buffer caps to power the board for at least 0.5 seconds, there should be no pop-off noise.
So: if you reroute the relay route, with a 230v relay in between, and put this after the on/off switch, and make sure there are enough buffer caps to power the board for at least 0.5 seconds, there should be no pop-off noise.
Hi there Onis,
Sorry for seeing your post so late!
Ive made a small board to solve this issue, its got 2 relays that are switched on delayed and they are put in between the speakers and the amplifier board.
this board is available free of charge for everyone that has bought a pre-amp from me, just mail me, and ill check and send.
the little board is connected as follows:
the new version of the tube buffer uses a delay circuit that's similar, a charging cap over the base of a transistor, and the transistor in his turn driving the Mosfet's gateto slowly open. the POP is caused by the DC-DC converter that whacks up the voltage so fast that the buffer capacitors are charged quickly, passing it on to the amplifier that passes it to the speakers, especially in sensitive speakers can then give a annoying POP.
ill send one off to you!
Greetings!
Arjen Helder
Sorry for seeing your post so late!
Ive made a small board to solve this issue, its got 2 relays that are switched on delayed and they are put in between the speakers and the amplifier board.
this board is available free of charge for everyone that has bought a pre-amp from me, just mail me, and ill check and send.
the little board is connected as follows:
An externally hosted image should be here but it was not working when we last tested it.
the new version of the tube buffer uses a delay circuit that's similar, a charging cap over the base of a transistor, and the transistor in his turn driving the Mosfet's gateto slowly open. the POP is caused by the DC-DC converter that whacks up the voltage so fast that the buffer capacitors are charged quickly, passing it on to the amplifier that passes it to the speakers, especially in sensitive speakers can then give a annoying POP.
ill send one off to you!
Greetings!
Arjen Helder
He has an issue with the pop-OFF sound, the pop-ON is already taken care of by your board...
Ah i see, i didn't see that just now !
I've hooked it up back here and when switching it off the pop is very small, not noticeable for me,because i don't have huge super efficient speakers. but i also know that many switch mode power supplies actually give a spike when switched off, that means in your case it could be allot bigger than what I'm measuring here.
The big caps on the board delays the switch off it a little, I'm quite sure that if we use a double pole switch for the power and the relay board the relay board should be fast enough to disconnect the speakers before the pop emerges.
best bet is use the double pole switch for the positive wire to the PCB and the negative black wire that runs to the relay board.
only option for soft start and stop on a DC-DC converter would be a MCU with programming, i will look in to this.
i have made a change for the boards now so that they do a soft start, the soft stop still needs to be considered.
Greetings,
Arjen Helder
I've hooked it up back here and when switching it off the pop is very small, not noticeable for me,because i don't have huge super efficient speakers. but i also know that many switch mode power supplies actually give a spike when switched off, that means in your case it could be allot bigger than what I'm measuring here.
The big caps on the board delays the switch off it a little, I'm quite sure that if we use a double pole switch for the power and the relay board the relay board should be fast enough to disconnect the speakers before the pop emerges.
best bet is use the double pole switch for the positive wire to the PCB and the negative black wire that runs to the relay board.
only option for soft start and stop on a DC-DC converter would be a MCU with programming, i will look in to this.
i have made a change for the boards now so that they do a soft start, the soft stop still needs to be considered.
Greetings,
Arjen Helder
ok what would be a very good power supply to use for this set up other than a smps ?!?!?
how about this ??http://cgi.ebay.co.uk/25-NEW-TOROIDAL-AMPLIFIER-TRANSFORMER-136VA-22v-12v-/260582115624?cmd=ViewItem&pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item3cabe78928
cheers Dom
how about this ??http://cgi.ebay.co.uk/25-NEW-TOROIDAL-AMPLIFIER-TRANSFORMER-136VA-22v-12v-/260582115624?cmd=ViewItem&pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item3cabe78928
cheers Dom
Last edited:
Hi there Onis,
Please consider the following,
1- in my eye's torroidial transformers are ideal, as long as a good secondary stage has been implemented with a proper bridge rectifier and big buffer capacitor.
2- if you rectify AC to DC, the voltage increases, the is roughly calculable with AC X 1.4 = DC, but the rectifier also eats about 1 volt usually.
best case you find yourself a 10V ~ 11V Transformer, thats right about good, and if it has 5 A max, its plenty!
Greetings!
Arjen Helder
Please consider the following,
1- in my eye's torroidial transformers are ideal, as long as a good secondary stage has been implemented with a proper bridge rectifier and big buffer capacitor.
2- if you rectify AC to DC, the voltage increases, the is roughly calculable with AC X 1.4 = DC, but the rectifier also eats about 1 volt usually.
best case you find yourself a 10V ~ 11V Transformer, thats right about good, and if it has 5 A max, its plenty!
Greetings!
Arjen Helder
Hi Arjen,
I suspect you missed my eMail I sent you days ago regarding your new speaker output relay board. If you don´t know who I am please PM.
I would be pleased if you would act on this issue. I disconnected the buffer amp + MK III TA2020 system meanwhile and would be happy to build up an well working system in a case soon.
Thanks
I suspect you missed my eMail I sent you days ago regarding your new speaker output relay board. If you don´t know who I am please PM.
I would be pleased if you would act on this issue. I disconnected the buffer amp + MK III TA2020 system meanwhile and would be happy to build up an well working system in a case soon.
Thanks
Hi , O.K. I have read this meanwhile from onis_uk:
http://www.diyaudio.com/forums/class-d/164635-arjen-helder-buffer-v2-5.html#post2227874
I am waiting till the technical issues cleared up completely.
http://www.diyaudio.com/forums/class-d/164635-arjen-helder-buffer-v2-5.html#post2227874
I am waiting till the technical issues cleared up completely.
Hi there Ipanema,
you could first of all double check your grounding for the input signal and power supply, and second of all, on the PCB nect to the potentiometer there is a via that is put there to ground the metal parts of the potmeter. you can scratch some coating away and solder a wire fron the via to the pot housing.
if you cannot solve it, you can send me a photo of the set-up and ill scan that for any connection trouble.
Greetings,
Arjen Helder
you could first of all double check your grounding for the input signal and power supply, and second of all, on the PCB nect to the potentiometer there is a via that is put there to ground the metal parts of the potmeter. you can scratch some coating away and solder a wire fron the via to the pot housing.
if you cannot solve it, you can send me a photo of the set-up and ill scan that for any connection trouble.
Greetings,
Arjen Helder
Arjen is seems to be in vacation...
maybe another expericenced member can help me how to connect the relay board to the TA2020 mkIII-board
The pic here from arjen:
http://www.diyaudio.com/forums/class-d/169520-curing-arjen-helder-amp-power-off-pop.html#post2231104
makes me a bit unsure regarding the powersupply connection ... instead of L or R he writes Input + and - . That´s really confusing and seems not to be well calculated before...
BTW: Arjen seems to be in vacation because I must start here the same question after he didn´t reply to my PM message
maybe another expericenced member can help me how to connect the relay board to the TA2020 mkIII-board
The pic here from arjen:
http://www.diyaudio.com/forums/class-d/169520-curing-arjen-helder-amp-power-off-pop.html#post2231104
makes me a bit unsure regarding the powersupply connection ... instead of L or R he writes Input + and - . That´s really confusing and seems not to be well calculated before...
BTW: Arjen seems to be in vacation because I must start here the same question after he didn´t reply to my PM message
Hi All,
I think these amps that can go low voltage / battery is better to use a small relay directly to the output signal of the preamp (use a switch to disable when gnd). this is a more elegant but requires a simple circuit lm339. .. or brutal connection of the small relay at switch (ON-OFF VCC) with a small constant R-C.
Regards
P.S. it is possible use a FET for switch to gnd signal from preamp-out.
I think these amps that can go low voltage / battery is better to use a small relay directly to the output signal of the preamp (use a switch to disable when gnd). this is a more elegant but requires a simple circuit lm339. .. or brutal connection of the small relay at switch (ON-OFF VCC) with a small constant R-C.
Regards
P.S. it is possible use a FET for switch to gnd signal from preamp-out.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.