Re: D-EF47 Tribute To Oliver Archut U47 Build Thread.
« Reply #480 on: March 30, 2021, 12:11:55 AM »
I ordered them on the 15th, and I'll still probably be waiting another month for them to show up. I'll probably wait until then to test other things like the EF184. I hate how annoying it is to take apart the U47 body, and I love how it sounds anyway with the EF80...so laziness wins. ;)
Haha I hear you...I have opened the mic so many times to try out stuff that I might need new screws soon. For the ef184 I have replaced the 100k plate resistor with 51k and went back to 100M grid resistors. First session tomorrow with this configuration so we’ll see how it behaves.


Re: D-EF47 Tribute To Oliver Archut U47 Build Thread.
« Reply #481 on: March 30, 2021, 10:06:21 PM »
Haha I hear you...I have opened the mic so many times to try out stuff that I might need new screws soon. For the ef184 I have replaced the 100k plate resistor with 51k and went back to 100M grid resistors. First session tomorrow with this configuration so we’ll see how it behaves.

Let us know how it goes. Post a demo if you can.

Re: D-EF47 Tribute To Oliver Archut U47 Build Thread.
« Reply #482 on: March 31, 2021, 01:10:42 AM »
Let us know how it goes. Post a demo if you can.
Unfortunately I don’t have permission to post samples from the session but here are my findings:
-Ef184 amperex sounds a little “dryer” and a little less 3D than the tfk ef802. Ef184 has more highs than 802 but the quality of the high end is a little different. 802 is smoother and 184 a little “papery”. 184 definitely a touch more sibilant. 802 has a little more emphasis around 2k and 184 seems to be smoother there with an emphasis a little higher up around 4K. Both tubes sound big in a different way. 184 seems to have more bass but 802 more upper bass “body”.
I would say that the 802 sounds more modern...higher fidelity and 184 more vintage.
Both tubes sound really good and maybe one might compliment a certain capsule more than the other. Also the 184 has a little more gain and is a touch “crunchier” and more compressed.
H+ 5.05 and B+105 for both tubes.
100k resistor replaced by 51k for both tubes.
Grid resistors 100M for 184 and 1G for 802.
Of course this is very subjective and not scientific so you might feel very differently about those tubes.
« Last Edit: April 01, 2021, 01:47:41 PM by Purplenoise »

Re: D-EF47 Tribute To Oliver Archut U47 Build Thread.
« Reply #483 on: April 01, 2021, 06:56:48 PM »
Unfortunately I don’t have permission to post samples from the session but here are my findings:
-Ef184 amperex sounds a little “dryer” and a little less 3D than the tfk ef802. Ef184 has more highs than 802 but the quality of the high end is a little different. 802 is smoother and 184 a little “papery”. 184 definitely a touch more sibilant. 802 has a little more emphasis around 2k and 184 seems to be smoother there with an emphasis a little higher up around 4K. Both tubes sound big in a different way. 184 seems to have more bass but 802 more upper bass “body”.
I would say that the 802 sounds more modern...higher fidelity and 184 more vintage.
Both tubes sound really good and maybe one might compliment a certain capsule more than the other. Also the 184 has a little more gain and is a touch “crunchier” and more compressed.
H+ 5.05 and B+105 for both tubes.
100k resistor replaced by 51k for both tubes.
Grid resistors 100M for 184 and 1G for 802.
Of course this is very subjective and not scientific so you might feel very differently about those tubes.

Very interesting. Why did you change the grid resistor between the two tubes?

Why did you drop the 100K value?

Things about both of those sound either appealing or like tradeoffs. I hope those capacitors get here soon, or my procrastination of other work might make me experiment with this sooner than later.

Thanks,
Josh
« Last Edit: April 01, 2021, 08:07:52 PM by JMPGuitars »

Re: D-EF47 Tribute To Oliver Archut U47 Build Thread.
« Reply #484 on: April 01, 2021, 07:44:35 PM »
Very interesting. Why did you change the grid resistor between the two tubes?

Why did you drop the 100K value?

Things about both of those sound either appealing or like tradeoffs. I hope those resistors get here soon, or my procrastination of other work might make me experiment with this sooner than later.

Thanks,
Josh
The plate resistor was changed to increase the plate current for the ef184 as it’s running a little cold with the 100k after the recommendation of some very knowledgeable members. Also AMI suggested this when using ef802. With ef802 I did 68k to bring the plate current closer to 0.5mA and it sounds good.
For the grid resistors I just thought those values sounded better with each tube. The value of the grid resistors affect not only the low end but the high end as well. Since ef184 was brighter I used 100M.
The new experiment is a Moby bv08 with same ratio but more windings for higher inductance...maybe a better match for ef800 and ef802. Just installed and first tests are very promising. Running an 802 with 68k instead of 100k and H+ at 5.2v