ook switches
proper XLR shortie is way to go , foolproof contact ...... and - it's either in or out
proper XLR shortie is way to go , foolproof contact ...... and - it's either in or out
Switches were correct. I am pretty much always using balanced, except for my SE only amps.
Ok, in single ended mode it works fine, channels are equal. Gonna swap the inputs again now.
Heh, I guess I threatened it enough. Working now. Thanks for the suggestion ZM.
New, more efficient speakers (Zu Druid V) showing more hum than the old Essences. I need to look at my cable routing, and consider a more shielded power supply cable. Some hum even from the Aleph J, which I did not hear before.
Ok, in single ended mode it works fine, channels are equal. Gonna swap the inputs again now.
Heh, I guess I threatened it enough. Working now. Thanks for the suggestion ZM.
New, more efficient speakers (Zu Druid V) showing more hum than the old Essences. I need to look at my cable routing, and consider a more shielded power supply cable. Some hum even from the Aleph J, which I did not hear before.
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Bias adjust: zero vdc across input resistor?
Hello all. The first power up of my new Aleph J and no smoke! One channel bias @ 400 mv with zero dc offset. (success).
The other channel has .002 mv across either input resistor. Turning the R27 pot has no effect, I have 24 VDC dc offset. This has to be a powerful clue, but I am unfortunately, "clueless".
Could anyone offer some guidance for trouble shooting?
TIA
John
Hello all. The first power up of my new Aleph J and no smoke! One channel bias @ 400 mv with zero dc offset. (success).
The other channel has .002 mv across either input resistor. Turning the R27 pot has no effect, I have 24 VDC dc offset. This has to be a powerful clue, but I am unfortunately, "clueless".
Could anyone offer some guidance for trouble shooting?
TIA
John
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Can't upload pics but...
I can't upload photos (tried 4 different times), but I just found Q2 and Q4 have the wrong part number on the channel that's not biasing properly. I have a ZTX 450 in the Q2 and a ZTX 550 in the Q4, instead of Q2 ZTX 550/Q4 ZTX450. I will replace soon as replacement parts arrive. I hope that this oversight did not cause any damage to the other components.
I can't upload photos (tried 4 different times), but I just found Q2 and Q4 have the wrong part number on the channel that's not biasing properly. I have a ZTX 450 in the Q2 and a ZTX 550 in the Q4, instead of Q2 ZTX 550/Q4 ZTX450. I will replace soon as replacement parts arrive. I hope that this oversight did not cause any damage to the other components.
In your reply push the 'paperclip' just above. Another window opens where you can select files from your computer to upload.
Sorry if this post is in wrong spot, but didn't know where to post. Assuming that power supply caps are properly uprated (and heatsinks), can you use a higher voltage than the recommended 25V in the power supply of the original (first version) Aleph 3? For example, 30V? Is there an advantage to this (i.e., amp will output more wattage)? Thanks!!
yes , you can
take care of dissipation and temperature of outputs
you'll have adequately increased power for 8R
take care of dissipation and temperature of outputs
you'll have adequately increased power for 8R
No hum, just music and heat!
Thanks to the help from this great DIY community, I have a wonderful Aleph J amplifier. There is no buzz from the toroidal transformer, no hum coming from the speakers just music! I'm using a Logitech Transporter balanced source connected to the XLR inputs.
I'm still tweaking the bias voltage (target .400vdc). After adding the cover, it drifts downward as the heat increases, causing me to "chase" the setting. I will attempt further adjustment when my IR thermometer arrives today.
If understand correctly, I should be able to maximize the gain by slightly increasing the 400 mvdc bias as long as I don't exceed 65C/55C heat sink/device
Gallery http://www.diyaudio.com/forums/gallery/showgallery.php?cat=2073
Thanks folks,
John
Thanks to the help from this great DIY community, I have a wonderful Aleph J amplifier. There is no buzz from the toroidal transformer, no hum coming from the speakers just music! I'm using a Logitech Transporter balanced source connected to the XLR inputs.
I'm still tweaking the bias voltage (target .400vdc). After adding the cover, it drifts downward as the heat increases, causing me to "chase" the setting. I will attempt further adjustment when my IR thermometer arrives today.
If understand correctly, I should be able to maximize the gain by slightly increasing the 400 mvdc bias as long as I don't exceed 65C/55C heat sink/device
Gallery http://www.diyaudio.com/forums/gallery/showgallery.php?cat=2073
Thanks folks,
John
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increased Iq will give (usually ) better sound , in layman terms
it doesn't have any influence on voltage gain of amp
Oh, ok then. Is Iq something that can be adjusted by me in this amp? I'll search DIY for "Iq"
bias voltage (voltage between source and gate of mosfet) is what's adjusting quiescent current (Iq) , which you're measuring as voltage drop across source resistor (you say 400mV)
so , Iq is (often) colloquially named as bias or bias voltage
it's important to know exact mechanismus , then you can call it whatever you want
so , Iq is (often) colloquially named as bias or bias voltage
it's important to know exact mechanismus , then you can call it whatever you want
Thank you ZM
Mechanism understood now, thanks. Always learning something on this forum 🙂
John
bias voltage (voltage between source and gate of mosfet) is what's adjusting quiescent current (Iq) , which you're measuring as voltage drop across source resistor (you say 400mV)
so , Iq is (often) colloquially named as bias or bias voltage
it's important to know exact mechanismus , then you can call it whatever you want
Mechanism understood now, thanks. Always learning something on this forum 🙂
John
One question,
Can I bypass C1, if the output of the preamp is transformer balanced?
Can I bypass C1, if the output of the preamp is transformer balanced?
Hi,
Does the AlephJ invert phase, or something like this?
I wanted to make some measurements with Arta on my speakers this morning and found that the impulse is upside down (on both channel).
I tried with a small class D amp I used to employ for measures when I had a tube amplifier and the impulse is OK.
I checked quickly the internal wiring of the Aleph, everything seems to be OK.
Is this the normal behaviour of this amplifier (in this case, I can easily revert the speaker cables connections on my speakers) or did I make something wrong?
Does the AlephJ invert phase, or something like this?
I wanted to make some measurements with Arta on my speakers this morning and found that the impulse is upside down (on both channel).
I tried with a small class D amp I used to employ for measures when I had a tube amplifier and the impulse is OK.
I checked quickly the internal wiring of the Aleph, everything seems to be OK.
Is this the normal behaviour of this amplifier (in this case, I can easily revert the speaker cables connections on my speakers) or did I make something wrong?