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DIY HiFi Supply Parts and Kits from Diy HiFi Supply

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Old 13th June 2011, 12:26 PM   #191
DECKY999 is offline DECKY999  Australia
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I finally nailed down the problem. Firstly to apologise to everyone for causing confusion regarding the heater voltage. The voltage was not a problem. I caused a short between the heater supply GND and the box (mains) GND by using wave washers under the PCB screws. They were making an intermittent contact with the PCB ground plane, through the silk printing, causing all those bizarre things that I explained earlier. As soon as I removed them everything went back to normal. I set the heater voltage to exactly 2.5V (measured at the valve socket). The bias was easily set to around 120V and remained stable. An increased level of buzz disappeared. However, I did use Loctite on those screws due to thermal cycling which will help to keep them in place.

My God that amp sounds good. Thanks for all the help.

PS. Another Tram is on it way to be assembled - I am sure I will have far less problems with it considering the lessons learned from the first one.
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Last edited by DECKY999; 13th June 2011 at 12:28 PM.
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Old 18th June 2011, 07:04 PM   #192
otto88 is offline otto88  Australia
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I'm moving country in 12 months does it come with dual 115/ 230 volt capable supply, or are they supplied 'separately'?
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Old 18th June 2011, 07:18 PM   #193
otto88 is offline otto88  Australia
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with the +6 db output, what is the output in mV?
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Old 19th June 2011, 03:13 AM   #194
Mihan is offline Mihan  New Zealand
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("I'm moving country in 12 months does it come with dual 115/ 230 volt capable supply, or are they supplied 'separately'?")

Yes it does, pages 12 and 15 of the manual show how to do this.

Last edited by Mihan; 19th June 2011 at 03:31 AM.
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Old 19th June 2011, 04:44 AM   #195
ThorstenL is offline ThorstenL  Germany
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Hi,

Quote:
Originally Posted by otto88 View Post
with the +6 db output, what is the output in mV?
Maximum output is quite high, several 10's of Volts, Gain is however 6dB (two times), so with the volume control all the way open and 2V in you get 4V out.

You allready found the answer to 115/230V, all it needs is a re-wire.

Ciao T
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Old 19th June 2011, 04:59 AM   #196
otto88 is offline otto88  Australia
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Thanks guys
is the manual available to - downloadable by potential customers?
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Old 19th June 2011, 05:06 AM   #197
ThorstenL is offline ThorstenL  Germany
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Hi,

Quote:
Originally Posted by otto88 View Post
Thanks guys
is the manual available to - downloadable by potential customers?
Yes, from this page (it is available from the Menu Item Download on all pages):

Technical Documents | Diy HiFi Supply

Ciao T
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Old 19th June 2011, 05:15 AM   #198
otto88 is offline otto88  Australia
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Thanks Thorsten
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Old 5th July 2011, 02:56 AM   #199
jacklee is offline jacklee  Hong Kong
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Hi Thorsten,

With the TRAM2 in my system I noticed that the left channel has a high freq noise occurring from time to time which sounds like some sort of oscillation. Each time the noise continue for 5~10 seconds and then stop, and then come back at a random time later. The level is very low (~20mV at the spk terminals but nonetheless audible).

Using a scope connected to the speaker terminals I can see the high freq noise has freq from tens of Khz to over 100Khz. To isolate the noise I have so far tried the followings:

1. To rule out interference from nearby power supplies I have switched off the TV, STB, PS3. No effect.
2. To rule out the source I disconnected the only source (CD player) from the TRAM2. No effect either.
3. To rule out the power amp I swapped the left and right amps (mono block). The noise follows the left channel output so the amp is not the cause.
4. To rule out interference from the TRAM2's second output connected to the subwoofers I disconnected them. No effect.
5. Tried different tubes for the output tube, rectifier, and 6AS7. No effect either.

The high-freq whining noise occurs regardless of whether the source has signal, and is independent of the vol control level (even at zero).

Any suggestions are most appreciated. Thanks.

Jack
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Old 5th July 2011, 08:37 AM   #200
ThorstenL is offline ThorstenL  Germany
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Hi,

Quote:
Originally Posted by jacklee View Post
The high-freq whining noise occurs regardless of whether the source has signal, and is independent of the vol control level (even at zero).Any suggestions are most appreciated.
Try gently "pinging" the tube with a biro or the like.

See if this creates the same noise.

Ciao T
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