Recent Posts

Pages: [1] 2 3 ... 10
1
Brewery / Re: Patents vs "rip-offs" vs clones etc
« Last post by pucho812 on Today at 02:18:35 PM »
The thing with  patents is protection and enforcement if it is worth time. For example  my clients, neighbor has a patent on a gesture. I kid you not.  The dude invented the way we use our fingers to zoom in when looking at an iphone and other devices that have a touch screen.  He has the patent for it, but has never enforced when others used  it because it's not worth the time. The guy also has over 150 patents to his name, no sure what else he has that he does not enforce.
2
Brewery / Re: Patents vs "rip-offs" vs clones etc
« Last post by JohnRoberts on Today at 02:17:43 PM »
i had a meeting with my patent lawyer again last week, he said
"you dont wanna get a patent to sue people, your patent will add value to your business when you sell it"
And it will add to his bank account right now.  ::) (I've known some patent lawyers who were that mercenary. One didn't even want to do a patent search in case we might find something that would preclude getting a patent and his payday . ::)   I did the search myself. )

Patents are a deep pockets game so yes it will have more value to a large company, and could help a large company defend against competition from another large company, but as I've already shared you don't always win in court (even with Peavey deep pockets).  Patents are also used by large companies to threaten small companies. My long term plan was to license my drum tuner technology to a big dog where the patent would be useful. That didn't happen, but I was not a very aggressive salesman. 

I don't want to discourage you but would advise paying extra attention to the claims writing in your patent.  The claims are where the rubber meets the road in court.  I wrote most of my last patent myself, only paying a big bux patent lawyer to write the claims section.

In hindsight the Peavey patent where we failed to shut down a copycat, could have benefitted from better claims writing, but neither I nor the lawyer expected it to end up in court, or realized how valuable the invention would turn out.  That lawyer probably grunted out several peavey patents a year and most are just expensive wall paper for Peavey to put in their war chest and brag about 

There is a well known dance to get a patent approved by a wet behind the ears patent examiner (put in extra claims for him to deny so he will feel like he is smart and did hid job), but that does not insure getting a strong patent you can defend in court later.

So spend some extra time thinking about how you would try to get around your own patent and close those doors with as broad claims as you can get through the PTO. Broad claims are harder to win but worth trying, because narrow (specific) claims can be worked around more easily. 

Good luck.. sorry if I sound like a negative nellie, just my life experience talking.

JR
3
Dynamic Processors / Re: D-LA2A Support Thread
« Last post by [silent:arts] on Today at 01:53:20 PM »
Looks like the relays are working fine.
If they wouldn’t work you would have the same sound with and without power.
4
The Lab / Re: New Capsule for AKG 414B-ULS?
« Last post by ln76d on Today at 01:52:45 PM »
Cleaning these cpasules can be tricky, it's not the best capsule for the first time cleaning.  The older the worse to clean.
Maybe Danny (Poctop) would be able to reskin it?
Thiersch don't reskin these capsule.


To elaborate on this one, Tim makes an excellent recreation of original brass ring CK12, which is by far superior than Teflon version which started with later production of 414EB and used in ULS series. As such, in fact, Tim's capsule will not be a replacement, but a significant upgrade.

Needless to mention, this one belongs to Microphone Forum, I believe...

Best, M

It depends - both capsules sounds different, and both are great. Maybe except the very first versions of teflon capsules. Upgrade? Depends...
Many times "teflon" capsules were much more universal for the different sound sources than brass Ck12.
Years ago i considered it as an upgrade, but very quickly i put back teflon capsule to my EB P48.
Anyway Tim capsule is Über great!

I'm interested in these capsules, but who is Tim?

also, I don't know if you can just buy capsules straight from him, but I've had a good experience with Land Audio Service getting my C414 repaired

http://www.timcampbell.dk/index2b.htm

Hello Marik, thank you so much for your input and explanation.

I have 2 modern 414 models, one 414 XLII and one 414 XLS.
Do you think Tim's capsule would also be a significant upgrade on this microphones.

If so, what could I be expecting as improvements?

Thank you so much

Not Marik, but hope it would be helpfull ;)
Modern "XL" series 414 using pretty high polarisation voltages - if i remember correctly something ca. 90V.
Tim capsule rather wouldn't handle it. Instead improvement rather broken capsule.
Another thing is that, even with modification of polarisation voltage drop, with brass CK12 it would be too bright.




5
Drawing Board / Re: Headphone amp
« Last post by JohnRoberts on Today at 01:47:03 PM »
Im guessing that without that resistor, the opamp would have to provide a dc offset of around 0.7V to keep one transistor turned on and thus mantain dc feedback.

Now that you mention the transformer, how come the lower terminal of the primary is connected to a pair of resistors, one which is a pot that goes back to the non-inverting input of the opamp, why not just connect the lower terminal of the trafo directly to ground?
As Abbey already mentioned that is some current feedback to linearize the transformer drive.

JR

PS: Speaking about personal monitor mix boxes for studios these only became popular after the bedroom recording boom made it possible for musicians to afford to record and mix themselves. Before that asking musicians to mix their own monitors would be met with a blank stare.  Typical studios would build their own headphone distribution systems and later personal mix systems. Now you buy almost anything you can think to make (cheaper and often better).
6
The Lab / Re: Troubleshooting Sansui AU-101 Amplifier
« Last post by JohnRoberts on Today at 01:42:16 PM »
I have a Sansui AU-101 amp that I bought cheap as one channel was dead. Opening it up showed that one of the fuses was blown and it blew immediately again on replacement. I managed to trace  down  a few dead/shorted transistors and got it going again but the output transistors on one channel were still getting hot so I thought it would be just a matter of time before they died again and went further solving the issue.
The voltage from the power supply was quite a bit off and pretty basic so I replaced it with a diy version, basically that same but with a voltage regulator after the rectifier diodes and a few more smoothing caps.  Where I'm at now is one channel works fine and is nice and quiet thanks to the new psu I assume, the other channel however causes the psu to crap out when I have the fuse in and my measurements indicate differences in resistance to ground when comparing channel to channel.
I'm pretty sure the problem is still somewhere into the output section but all transistors and caps test fine. My knowledge is pretty limited so if anyone has any advice about where to look I'd appreciate it. Below is the schematic.
When you have a stereo anything with one channel working and one channel not, you can probe voltages on the working side and the questionable side to look for differences. The differences will eventually lead you to the remaining problems. Of course be careful probing around with power on so you do not break something else with a slipped probe. (it happens).

There is a trimpot for setting output class A bias. (VR801). Set that for minimum R for minimum class A current and heat at idle. (BTW that is not a very clever design, since trimpots are known to fail open circuit so, output stage goes to full bias if trimpot fails.  A safer design would use a fixed resistor with trimpot in parallel so a bad trimpot doesn't kill the amp.

JR

7
Drawing Board / Re: Headphone amp
« Last post by Dualflip on Today at 01:41:25 PM »
I've seen the same strategy used in a high current power amp output stages to save a few parts (driver stage), but there is no free lunch and class AB delivers a true benefit in reducing the turn on time of power semiconductors (moot with modern class D switching stages).  Waiting for the devices to turn on is what causes crossover distortion at high audio frequency in output stages.

Headphone amps operate at much lower current and a decent modern (fast) op amp could probably deliver a respectable output. The schematic posted driving a transformer is probably not a very low Z, high current output.

JR

Im guessing that without that resistor, the opamp would have to provide a dc offset of around 0.7V to keep one transistor turned on and thus mantain dc feedback.

Now that you mention the transformer, how come the lower terminal of the primary is connected to a pair of resistors, one which is a pot that goes back to the non-inverting input of the opamp, why not just connect the lower terminal of the trafo directly to ground?
8
Brewery / servicing little nightmare of the day !
« Last post by zamproject on Today at 01:39:43 PM »
Hi all

I'm currently servicing/restoring/repairing/recaping, whatever ...ing available, a 80' beast syth, Jupiter 8...
I take excessive care about what I'm doing on it, since market become crazy about it, and some part become hard to find.
So far only one voice dead and I find the faulty transistor network (for VCO) at local electronic shop !
Today PSU recap, I do this one inside the frame for practical reason regarding how all power are distributed, as soldered at PSU PCB.
Then I cut a tin desoldering brain extremity... jump somewhere inside despite my care to not let him fall (I don't do it on top of the frame...).
I try to find it more than one hour, I "clearly" ear it ding-ding-ing  (no visual of the fly) I also check all around on the floor
Not a sign... and don't want to power the JP8 before I put my hand on it  :(

It happen me once time ago with a capacitor(or resistor) leg in my console frame, I give up after 2 hours, it was my stuf and if a short happened, it's all on me, no problem.
This syth is not mine.

So, I just take few minute here, because when you focus to much looking for something, you usually don't find it, and the day after it's just the most visible part in the middle of the table.

Best
Zam
9
Drawing Board / Re: Headphone amp
« Last post by JohnRoberts on Today at 01:31:17 PM »
Thanks, it makes sense.
I've seen the same strategy used in a high current power amp output stages to save a few parts (driver stage), but there is no free lunch and class AB delivers a true benefit in reducing the turn on time of power semiconductors (moot with modern class D switching stages).  Waiting for the devices to turn on is what causes crossover distortion at high audio frequency in output stages.

Headphone amps operate at much lower current and a decent modern (fast) op amp could probably deliver a respectable output. The schematic posted driving a transformer is probably not a very low Z, high current output.

JR
10
The Lab / Re: New Capsule for AKG 414B-ULS?
« Last post by outoftune on Today at 01:13:56 PM »

See the Neumann doc attached

There's also this thread:

https://groupdiy.com/index.php?topic=22287.msg263439#msg263439

pics in the thread are gone , but I have the original one woth pictures saved in my hardrive and I can send you over email if you need it
thank you for the document, i will email you about the pictures.
Pages: [1] 2 3 ... 10