Search found 42 matches
- Mon Nov 28, 2022 6:51 pm
- Forum: Technical Discussion
- Topic: pot conundrum
- Replies: 3
- Views: 646
Re: pot conundrum
Passive fx loops are trouble. The best Passive FX loop I have ever been able to pull off is a 470k + 15k voltage divider after the tone stack = 14.56k output impedance. 20ft cable = 1nF = 10.931kHz. Just with a cable you will hear that... it may even be nice. Maybe. Most people will not like this. B...
- Sat Nov 26, 2022 11:39 pm
- Forum: Technical Discussion
- Topic: Bogner Helios: RF Radio Noise
- Replies: 8
- Views: 1000
Re: Bogner Helios: RF Radio Noise
You need to shield the input jack and tie that shield to ground. All the metal on the hot side of the jack acts like one big ass antenna. I make a thin cardboard form and then contact cement.005” thick brass around it. I get this brass sheet from hobby shops or on line. I mainly use this mod on the...
- Fri Nov 18, 2022 2:01 am
- Forum: Technical Discussion
- Topic: Squawk box speaker issues
- Replies: 7
- Views: 484
Re: Squawk box speaker issues
Here is another with resonant frequency at 100Hz, but without quite as extended of a top end:
https://www.parts-express.com/GRS-5PF-8 ... er-292-405
https://www.parts-express.com/GRS-5PF-8 ... er-292-405
- Mon Nov 14, 2022 6:42 pm
- Forum: Speakers and Cabinets
- Topic: ISO Cabs?
- Replies: 10
- Views: 6253
Re: ISO Cabs?
We have closed back cabs and then the have closed AND closed front cabs. I've never been able to wrap my head around how to think about the isolation cab where one side of the speaker doesn't face a large room. Possibly this is a good solution. Essentially a speaker mounted on a board in a closed bo...
- Thu Jun 16, 2022 11:48 pm
- Forum: Garage Talk
- Topic: LTSpice IOS grounding???
- Replies: 6
- Views: 1232
Re: LTSpice IOS grounding???
Can't do LTSpice on Mac without the shortcut sheet!
https://www.analog.com/media/en/news-ma ... ice-models
https://www.analog.com/media/en/news-ma ... ice-models
- Mon Jun 06, 2022 11:14 pm
- Forum: Technical Discussion
- Topic: shielded wire gauge minimum for typical marshall preamp
- Replies: 12
- Views: 1199
Re: shielded wire gauge minimum for typical marshall preamp
26 awg should be good. Pickup wiring typically is 28 awg and we know that stuff gets bent all around by the average person with a soldering iron.
- Fri May 27, 2022 11:09 pm
- Forum: Technical Discussion
- Topic: Low Pass Filter: Math vs Practice
- Replies: 16
- Views: 2070
Re: Low Pass Filter: Math vs Practice
Thats interesting. I always assume the smaller the resistor, the lower the noise. I would be interested to know what the final verdict on if large grid stoppers cause noise or not. That 470k gives the mesa dual rectifier a lot of its characteristic tone- mostly that it darkens it. Additionally, it c...
- Thu May 26, 2022 8:22 pm
- Forum: Technical Discussion
- Topic: Low Pass Filter: Math vs Practice
- Replies: 16
- Views: 2070
Re: Low Pass Filter: Math vs Practice
The 20p is noticeable when you remove it, but not all that much. And certainly there are no oscillations when you remove it. You can also jump the 470k with a 10k, which is much more effective due to Miller capacitance-still no oscillations. It will basically sound like a DR, but much less dark, 90'...
- Wed May 18, 2022 4:57 pm
- Forum: Marshall Discussion
- Topic: Jose modded Steve Vai Marshall
- Replies: 7
- Views: 3171
Re: Jose modded Steve Vai Marshall
Totally agree here! I think you have perceptive earsReeltarded wrote: ↑Mon Apr 04, 2022 6:11 am You should add the simple master after the tone stack on a separate control... monsterous at around 7+7.. its like free steaks.
- Wed May 18, 2022 4:54 pm
- Forum: Marshall Discussion
- Topic: Marshall JMP 50W Master Volume ST1 iss.202 oscillation
- Replies: 12
- Views: 2524
Re: Marshall JMP 50W Master Volume ST1 iss.202 oscillation
I mean turn bias as far negative as possible to lower current draw. That may not totally work though as something oscillationg can reach absolute maximums. I'd probably remove the phase inverter tube before testing while powered on. Good luck. Might be a good idea to consult a tech. This amp is prob...
- Sun May 15, 2022 10:54 pm
- Forum: Marshall Discussion
- Topic: Marshall JMP 50W Master Volume ST1 iss.202 oscillation
- Replies: 12
- Views: 2524
Re: Marshall JMP 50W Master Volume ST1 iss.202 oscillation
Before you do anything, jack that -Vbias up all the way! It's hard to work on something that is melting down.
I've never seen a 12ax7 red plating. The plate resistors should limit current to well below what is needed to red plate. Very peculiar.
I've never seen a 12ax7 red plating. The plate resistors should limit current to well below what is needed to red plate. Very peculiar.
- Sat May 07, 2022 5:49 pm
- Forum: Garage Talk
- Topic: "No More Russian Vacuum Tubes in 2022"
- Replies: 105
- Views: 17625
Re: "No More Russian Vacuum Tubes in 2022"
There are a lot of Russian tubes out there being horded. I know higher ups in several online distributors that just pulled their listings because certain people/companies were making multiple order/day for 500tubes/order. So, they could either totally sell out, or take the listing offline and wait t...
- Mon Apr 04, 2022 5:59 am
- Forum: Marshall Discussion
- Topic: Jose modded Steve Vai Marshall
- Replies: 7
- Views: 3171
Re: Jose modded Steve Vai Marshall
Yeah, that's about how I understand it. 1)Take a Plexi 2)add a 12ax7, but only use 1/2 3)make a bright channel to cascade into the plexi and put the "jumpered channels" on the push pull switch to jumper them. 4)install DPDT push pull 1M master volume. configure the DPDT to swap the master volume bef...
- Tue Feb 15, 2022 5:57 pm
- Forum: Speakers and Cabinets
- Topic: Alternative cabinet materials
- Replies: 15
- Views: 6662
Re: Alternative cabinet materials
1/8" panels? Wow. That is thin! You could cut that easily with a CO2 laser. You can even cut 1/4" with most CO2 lasers over 50 watts.
- Wed May 05, 2021 7:30 pm
- Forum: Technical Discussion
- Topic: 2021 Monkeymatic Black Butte SMPS version!
- Replies: 34
- Views: 3044
Re: 2021 Monkeymatic Black Butte SMPS version!
I see! The 300V B+ is a bit low for 50W with the usual output transformers. Ho would you tackle that? Re-label the secondaries to reflect a lower primary impedance? Really interested to hear of your results. Has anyone discovered the schematic? Maybe it could be modified to deliver ~477v B+? (first ...