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PostPosted: 14 Nov 2017, 20:19 
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Nice to know Matt.

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PostPosted: 14 Nov 2017, 20:50 
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Thanks, Matt!

We have a Hammond engineer here that came years ago to answer why some were made in China. Maybe he'll pop in and give us his :2c: ?

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PostPosted: 15 Nov 2017, 07:07 
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Ran the amp for a whole after of listening through my Pi server and HDMI audio ripper. Amp didn't catch fire and the house didn't burn down. I've drop the total HT current draw so this may help.

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PostPosted: 15 Nov 2017, 07:10 
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mwhouston wrote:
I have mentioned in this thread and one other that this little HP amp was showing some distortion. Well it appears my Pi music server and HDMI audio ripper was putting out over 2V thus overdriving the E88CC which is biased at 1.5V. By dropping the input volume by 70% coming out of the Pi and bring up the volume on the Sanctum I now have distortion free listening.

Funny how on classical music I never heard a single note of distortion but on some jazz tracks and rock tracks it would appear. I'm going to upgrade the tranni then all should be fine.


It appears I only have to drop the output from the audio ripper by 10%. Works well now.

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PostPosted: 15 Nov 2017, 18:27 
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Here's a hard choice. With the Beyerdynamic DT 770 Pro 250ohm closed back headphones my little amp is absolutely dead quiet. I can't pick the diference between it turned on or off.

But the my Senhieser 700s, open back 32ohm there is a very slight background hum. When the music is on, even quietly the hum cannot be heard. The Senhiesers outperform the Beyers (though I think these phones are really excellent particularly at the money) by a good margin. When others are home the closed back are the way to go but when on my own....

Which way would you go?

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PostPosted: 15 Nov 2017, 21:10 
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Slightly off topic: See my write up on Hammond transformer temperature and heating here: http://diyaudioprojects.com/Forum/viewtopic.php?f=5&t=6098

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PostPosted: 16 Nov 2017, 01:13 
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I may have a simple solution to my dilemma, put a couple 33ohm resistors in series with the phone jack so the amp sees 65ohms with 32ohm phones. This will drop the slight hum, lower the corner frequency from 50Hz to 25Hz and allow me to use the Senheisers phones with hum suppressed. Should have little effect on my 260ohm Beyers.

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PostPosted: 20 Nov 2017, 17:18 
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mwhouston wrote:
Here's a hard choice. With the Beyerdynamic DT 770 Pro 250ohm closed back headphones my little amp is absolutely dead quiet. I can't pick the diference between it turned on or off.

But the my Senhieser 700s, open back 32ohm there is a very slight background hum. When the music is on, even quietly the hum cannot be heard. The Senhiesers outperform the Beyers (though I think these phones are really excellent particularly at the money) by a good margin. When others are home the closed back are the way to go but when on my own....

Which way would you go?


I have a similar issue with the Sennheiser HD650,Senn HD700 and the Sony MDR-XB700 i can hear a slight hum only when no music is playing but not with the Beyer DT880 600 ohms it's quiet with this headphone.


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PostPosted: 20 Nov 2017, 20:08 
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Alex Q wrote:
mwhouston wrote:
Here's a hard choice. With the Beyerdynamic DT 770 Pro 250ohm closed back headphones my little amp is absolutely dead quiet. I can't pick the diference between it turned on or off.

But the my Senhieser 700s, open back 32ohm there is a very slight background hum. When the music is on, even quietly the hum cannot be heard. The Senhiesers outperform the Beyers (though I think these phones are really excellent particularly at the money) by a good margin. When others are home the closed back are the way to go but when on my own....

Which way would you go?


I have a similar issue with the Sennheiser HD650,Senn HD700 and the Sony MDR-XB700 i can hear a slight hum only when no music is playing but not with the Beyer DT880 600 ohms it's quiet with this headphone.

It maybe to do with sensitivity. One more than the other. For low impedance phones or high sensitivity phones a 100ohm R in series with both channels works a treat.

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PostPosted: 05 Dec 2017, 18:08 
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Here is the next base for the next Sanctum. This time Cyprus finished with a rubbing oil.

Hope to have the top plate drilled and primed today. Also I discovered NOS or near NOS RCA 6AS7 can sell for $100 each. I shipped off what I thought was my only RCA tube with the last Sanctum. It sounded the best between a GE 6080 and a Svetlana 6AS7. Between those two I felt the Svetlana better. Has anyone compared a 6080 with a 6AS7. Are they both apples or is one an orange?

But on digging through my boxes of tubes I found three more RCAs. This build will surely have one of them.
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