It turned out around 135mA. I split the difference from your spec.
Interestingly, I ordered two pairs of DN2540s in separate orders. The first batch, from the prototype, both measured about 1.0V Vgs. The second batch measured about 1.3V. I'm glad they came in matched pairs so I could have the same values for R10, and matched currents, channel-to-channel.
Interestingly, I ordered two pairs of DN2540s in separate orders. The first batch, from the prototype, both measured about 1.0V Vgs. The second batch measured about 1.3V. I'm glad they came in matched pairs so I could have the same values for R10, and matched currents, channel-to-channel.
I just put the Aikido back in the system. Listening to Dolby again, it may be my imagination, but it sounds "splashy" to me compared to what I remember from yesterday.
I had this bad thought: maybe my DCG3 compensation capacitors have messed up the bandwidth and I'm hearing HF rolloff. So I just did a rough check and it looks like it's -3dB about 2.5 MHz.
DC to light...
I had this bad thought: maybe my DCG3 compensation capacitors have messed up the bandwidth and I'm hearing HF rolloff. So I just did a rough check and it looks like it's -3dB about 2.5 MHz.
DC to light...
Yes, absolutely. This is really interesting. Yesterday morning with the DCG3 in the system, I was turning the volume up and up as I slowly went deaf and it never sounded harsh (hence my wife's comment). Now, I'm literally in the other room because I can't stand listening to this... noise.
This really puts the lie to the truism about transistors sounding harsh and tubes sounding smooth. There's just no point to using the Aikido anymore.
-Henry
This really puts the lie to the truism about transistors sounding harsh and tubes sounding smooth. There's just no point to using the Aikido anymore.
-Henry
I've just been implementing an Ian Canada dac stack for my brother and his system. We went with a passive IV and it initially gave low output. His amplifier had adjustable input sensitivity from 2v thru 4v via a few steps. I guess it was just flicking thru different R values. Seemed a good idea to me. It allowed us to avoid clipping with a near 5v DAC output and also to lift the levels with a lower 2v passive IV out with a lower output DAC.
So would seem a reasonable idea to me!
So would seem a reasonable idea to me!
As a point of philosophy, I would rather not bring an internal node of a circuit with 130dB of open-loop gain out to a front panel switch for the purposes of adjusting the feedback factor. The properties of the DCG3 circuit will vary as you change the gain, which is probably fine, but still irks me.
I would propose that the proper way to deal with a hot source is to pad it down. But it's not my project, so by all means feel free to do what floats your boat.
I would propose that the proper way to deal with a hot source is to pad it down. But it's not my project, so by all means feel free to do what floats your boat.
Hpasternack your knowledge far outweighs mine and so I won't deny that what you say isn't good wisdom.my brothers case isn't a DCG3, he has a fancy commercial integrated class a amp and the gain settings are adjusted within a menu via a remote so maybe relays at play. I don't know!
But good information about not bringing a variable gain switch to the front panel for us beginners.
But good information about not bringing a variable gain switch to the front panel for us beginners.
If there is serious need for two gain levels on hand, someone could try a mini board connected with short pins to the R6 pads having a relay selecting between two Rf (R6) values controlled from a front panel switch. A postage stamp size cut out from a perforated board should be alright for a test. There are also various places in the preamp to tap DC for operating the relay.
Electroswitch makes a four-pole, two deck, six-position switch of very high quality that could be used to implement a switched L-pad pre-attenuator. With some algebra, you can select resistor values that maintain constant input impedance.
Mouser has three in stock: https://www.mouser.com/ProductDetail/Electroswitch/C4D0406S-A/?qs=lwrXE7cXt4TwpQEUJIHtwg%3D%3D
I'm using the single-deck version of this switch for my input selector. It's possible to do the pre-attenuator with a two-pole switch, but it's more elegant to switch both sides (if you can stomach two additional contacts in the signal path).
-Henry
Mouser has three in stock: https://www.mouser.com/ProductDetail/Electroswitch/C4D0406S-A/?qs=lwrXE7cXt4TwpQEUJIHtwg%3D%3D
I'm using the single-deck version of this switch for my input selector. It's possible to do the pre-attenuator with a two-pole switch, but it's more elegant to switch both sides (if you can stomach two additional contacts in the signal path).
-Henry
Thanks, Salas.
I've been reading headphone reviews for the past couple of months. I decided I can't justify going to the next price tier, and without an opportunity to audition headphones in person, the HD600 series seems like the safest bet, and undoubtedly a very good choice in any case.
In spite of the $100 difference in list price, the street price of the two models is about the same. The drop.com HD6xx seems almost like a no-brainer option at a much lower cost, but there are enough negative reviews of the company that I hesitate to pull the trigger.
I'm going to mull it over, but will probably place an order soon.
My relay boards cleared customs in New York City today, so if I designed it right I should be able to finish up the project next week. Knowing me, I probably screwed up and will have to do another iteration, LOL.
I believe my implementation is sufficiently true to the original to call it a "DCG3." So, I can say I am still enjoying the DCG3 very much. I have a full set of parts for a second signal board (I ended up salvaging most of the components from my prototype) and am thinking of building a second unit in a little larger form factor for permanent use in my main system.
I'm afraid the Aikido preamp has been designated for recycling, though perhaps I should invest some time in trying to make it sound better before I give up on it.
-Henry
I've been reading headphone reviews for the past couple of months. I decided I can't justify going to the next price tier, and without an opportunity to audition headphones in person, the HD600 series seems like the safest bet, and undoubtedly a very good choice in any case.
In spite of the $100 difference in list price, the street price of the two models is about the same. The drop.com HD6xx seems almost like a no-brainer option at a much lower cost, but there are enough negative reviews of the company that I hesitate to pull the trigger.
I'm going to mull it over, but will probably place an order soon.
My relay boards cleared customs in New York City today, so if I designed it right I should be able to finish up the project next week. Knowing me, I probably screwed up and will have to do another iteration, LOL.
I believe my implementation is sufficiently true to the original to call it a "DCG3." So, I can say I am still enjoying the DCG3 very much. I have a full set of parts for a second signal board (I ended up salvaging most of the components from my prototype) and am thinking of building a second unit in a little larger form factor for permanent use in my main system.
I'm afraid the Aikido preamp has been designated for recycling, though perhaps I should invest some time in trying to make it sound better before I give up on it.
-Henry