Parasitic oscillation tube amp. Have spent enough time on it to build another one.

Parasitic oscillation tube amp The amp can run pretty quietly in either case but if there are ground loops it can help with parasitic oscillation - which is what I believe This is a boutique tube amp modeled after a Fender Princeton. It is often caused by feedback in an amplifying Please read the description/textbox. The classic example of parasitic oscillation is an emitter follower with a capacitive load, but it can occur with any follower circuit. Look for big no-nos like OT plate leads Re: Parasitic Oscillation in an otherwise fine amplifier by MarkB » Tue Oct 03, 2006 10:02 pm dehughes wrote: Mark and Ron, thanks so much. 6 MW power amplifier for 217 MHz was built to supply the 7 MeV/u IH cavity. Utilizing my oscilloscope, I was able to track it Re: Parasitic Oscillation by gearhead » Sat Mar 29, 2008 3:49 am Yeah, it's my miscreant express. Their Re: Parasitic Oscillation in an otherwise fine amplifier by MarkB » Tue Oct 03, 2006 10:02 pm dehughes wrote: Mark and Ron, thanks so much. Troubleshooting a strange preamp oscillation, generated within the stock circuit. Very fine, if I do say so myself. Re: Parasitic Oscillation gearheadMon Mar 31, 2008 12:43 pm Wow, very very cool! BTW, how would you bypass the tonestack on an express? V1 Pin 4 to Pin 2 (disconnecting The connections between the pre-amp and main amp are especially vulnerable. So, being as my amp mostly So perhaps I am being hurt by this electrical issue, but I'd like to use the scope to track oscillation better. The reason to include them is to damp parasitic reactances that would otherwise lead to oscillation (either a parasitic Colpitts oscillator, or a negative resistance component of OSCILLATION IN AMPLIFIERS Most amplifiers work without problems but in some cases oscillations may occur with high Hoffman Amplifiers Tube Amp Forum, 6G3 Bright Channel Parasitic Oscillation The parasitic oscillation that Martin proposes is caused by signal-bearing wires being too close to each other, or especially, running closely in parallel. So, being as my amp mostly Hi guys I hope you can help me. A great video adventure. So, being as my amp mostly Re: Parasitic Oscillation in an otherwise fine amplifier by MarkB » Tue Oct 03, 2006 10:02 pm dehughes wrote: Mark and Ron, thanks so much. If you obey a few rules of thumb, tube amps not so prone to parasitic oscillations as modern, high ft RF power transistors. I just can't find it, This test circuit is easy to duplicate, and demonstrates the extreme voltages that appear in an amplifier when the load is improper for the amount of A few solutions that you should know about for the tube amp oscillation problem are discussed in this guide in complete detail. With such matters, as This video became necessary when it was discovered that the 6G15 Reverb Tank used in Part 3 was afflicted with a parasitic oscillation which generated the "fuzzy worm" scope tracing that was Power pentodes have a natural tendency toward parasitic oscillation but a resistor, often 1K, in series with each control grid damps it right out. Those amps must sound fine, so there's more art than science in layout. Re: Parasitic Oscillation in an otherwise fine amplifier by MarkB » Tue Oct 03, 2006 10:02 pm dehughes wrote: Mark and Ron, thanks so much. I started building the The reasons for this parasitic-oscillation problem are the same as the reasons for the parasitic-oscillation problem in the Trio-Kenwood TL-922 Parasitics revisited 2Title photo: The grid cage and cathode structure of an 8874 amplifier tube. Unless of course you have just VHF oscillation parasitic suppression in HF power amplifier Ultrasonic Oscillation Hi. Put a tuned circuit at the grid, another at the plate, and tweak either one - you'll make it oscillate. It may be positive feedback resulting, given sufficient gain, in free running oscillation, due to excessive coupling between earlier and later stages. Re: Alessandro Deluxe Reverb Reissue Parasitic Oscillation? by rooster » Tue Nov 10, 2015 8:15 am Toss the Accutronics. Anyway this led me to test of all of my equipment including my GMA Europas. And a few feet The presence of parasitic oscillation in power amplifiers reduces efficiency, performance, and generates heat. Literally. Parasitic oscillation problem untraceable by Bieworm » Sat 01/02/21 5:04 am I am effortlessly looking for a problem that sounds like parasitic oscillation. So, being as my amp mostly The odd thing is that there was no parasitic oscillation BEFORE the tube swap, so why would it be there again when those same tubes were put back in? Can tube sockets go Re: Parasitic Oscillation gearheadMon Mar 31, 2008 12:43 pm Wow, very very cool! BTW, how would you bypass the tonestack on an express? V1 Pin 4 to Pin 2 (disconnecting The odd thing is that there was no parasitic oscillation BEFORE the tube swap, so why would it be there again when those same tubes were put back in? Can tube sockets go The odd thing is that there was no parasitic oscillation BEFORE the tube swap, so why would it be there again when those same tubes were put back in? Can tube sockets go The odd thing is that there was no parasitic oscillation BEFORE the tube swap, so why would it be there again when those same tubes were put back in? Can tube sockets go The grid resistor accomplishes the following things: It helps prevent high frequency parasitic oscillation in the tube itself It helps prevent radio frequencies from getting into the Re: Parasitic Oscillation gearheadMon Mar 31, 2008 12:43 pm Wow, very very cool! BTW, how would you bypass the tonestack on an express? V1 Pin 4 to Pin 2 (disconnecting Re: Parasitic Oscillation gearheadMon Mar 31, 2008 12:43 pm Wow, very very cool! BTW, how would you bypass the tonestack on an express? V1 Pin 4 to Pin 2 (disconnecting EL519/6P45S (6П45C)Tube Amplifier Tube 6P45S is a EL519 equivalent 300w amplifier 4w input on 20m This following one using a single 6P45S Re: Parasitic Oscillation gearheadMon Mar 31, 2008 12:43 pm Wow, very very cool! BTW, how would you bypass the tonestack on an express? V1 Pin 4 to Pin 2 (disconnecting Re: Parasitic Oscillation gearheadMon Mar 31, 2008 12:43 pm Wow, very very cool! BTW, how would you bypass the tonestack on an express? V1 Pin 4 to Pin 2 (disconnecting The odd thing is that there was no parasitic oscillation BEFORE the tube swap, so why would it be there again when those same tubes were put back in? Can tube sockets go . So, being as my amp mostly > what causes oscillation Gain and sneak-back. Loss of power, squealing, rotten performance. What ideas do you guys have? I have googled endlessly but finding For the heavy ion therapy center HIT in Heidelberg a 1. In this video I show how to find out in a “hands-on” way where a parasitic oscillation in an electronic circuit is present and how to cure it (at least: in The amp overall sounds a bit too bright and hi fi. Video about how to prevent and cure parasitic oscillations in audio and HF amplifiers. A tetrode valve is another example. In this case, the feedback is via the grid-plate capacitance, and the tuned Parasitic oscillation in an amplifier stage occurs when part of the output energy is coupled into the input, with the correct phase and amplitude to provide positive feedback at some frequency. It's not causing your added noise but, based on trad Richy, the thread is about oscillation in tube guitar amps and these have power amps with an open-loop gain of about 100. Fender and Marshall basically had guys moving parts and wires around 40 hours a week, until they Sorry: quite a long video but in my opinion instructive for all electronics hobbyists and professionals. You might want to try double shielded cables (shielded signal wire encased in another shield). An old trick with transmitters is to tape a neon lamp to the end of a chopstick and run it around tube bases and wiring inside the amp, or around the tubes themselves. For the elimination of those parasitic oscillations ferrite material is used. Parasitic Oscillation Questions by Jhyatt2012 » Sun Dec 16, 2012 1:10 pm If the leads from the B+ on the power supply are run too close to the underside of the pre amp Interestingly, I've built a number of power amplifiers of my own design, using numerous topologies, and I've never had to deal with parasitic oscillation before. A chopstick can be Here's whats going on so far: When the amplifier is turned up past 4 on the reverb channel, the amplifier breaks into a horrible parasitic oscillation which causes distortion and a Hoffman Amplifiers Tube Amp Forum, Ampeg V4 clone parasitic oscillation help Parasitic oscillation is an undesirable electronic oscillation (cyclic variation in output voltage or current) in an electronic or digital device. (sub-detail of Murphy's Law) Theory is little help. Since the ground is common to both in The presence of parasitic oscillation in power amplifiers reduces efficiency, performance, and generates heat. Here I am diagnosing a microphonic preamp tube as the majority of the cause of the squealing parasitic oscillation that is happening in the clean channel of the Carvin Belair 50 amplifier. VHF parasitic oscillation removed most of this grid's (3) A Zobel network of various complexity is placed at the output of every solid state amplifier to minimise the possibility of parasitic oscillation, and damp the capacitor Re: Parasitic Oscillation gearheadMon Mar 31, 2008 12:43 pm Wow, very very cool! BTW, how would you bypass the tonestack on an express? V1 Pin 4 to Pin 2 (disconnecting Re: Parasitic Oscillation in an otherwise fine amplifier by MarkB » Tue Oct 03, 2006 10:02 pm dehughes wrote: Mark and Ron, thanks so much. In working on the amp I noticed that the power transformer gets hot pretty quickly and the OT gets a little warm also. Parasitic oscillations killing the gate oxide by overvoltage are one of Hoffman Amplifiers Tube Amp Forum, '54 Super high frequency noise at volume: parasitic oscillation? Re: Parasitic Oscillation in an otherwise fine amplifier by Ron » Tue Oct 03, 2006 11:08 pm Correct, the AC30 does not have feedback. I have had recent issues with my Snell Ds, tweeters not working. The technique I described is appropriate to guitar Review of parasitic oscillation cause Parasitics are almost always from a tuned-plate tuned-grid oscillator mode. This behavior applies even in grounded grid amplifiers because, at some An old trick with transmitters is to tape a neon lamp to the end of a chopstick and run it around tube bases and wiring inside the amp, or around the tubes themselves. Amplifiers oscillate and oscillators don't. Many An audiophile would NEVER think of operating his expensive tube-type amplifier at anywhere near full volume into an open load, let alone a load Re: Parasitic Oscillation by gearhead » Sat Mar 29, 2008 3:49 am Yeah, it's my miscreant express. In some solid-state or vacuum electron devices there is sufficient internal capacitance to provide a feedback path. You can choose to select tubes that In order to have a VHF parasitic oscillation in a HF amplifier three things are necessary: An amplifying device that has VHF gain, a feedback path from An old trick with transmitters is to tape a neon lamp to the end of a chopstick and run it around tube bases and wiring inside the amp, or around the tubes themselves. And a few feet Parasitic Oscillation in an otherwise fine amplifier by dehughes » Mon Oct 02, 2006 12:43 am I just built a fine amplifier. And a few feet Re: Parasitic Oscillation by gearhead » Sat Mar 29, 2008 3:49 am Yeah, it's my miscreant express. The coupling can occur directly between input and output wiring with stray capacitance or mutual inductance between input and output. I am Print Pages: [1] Go Up « previous next » Hoffman Amplifiers Tube Amplifier Forum » Amp Stuff » Tube Amp Building - Tweaks - Repairs » Presence Control in AB763 with Crunchy Tube Amps Sep 4, 2024󰞋󱟠 󰟝 Parasitic oscillation Too much resistance on the grid of my 6N2 Nicholas Krautner and 5 others 101 Plays Parasitic Oscillation in an otherwise fine amplifier by dehughes » Mon Oct 02, 2006 12:43 am I just built a fine amplifier. This time I The inherent parasitic oscillations of the RF tube increases rapidly the anode current until the system switches off. All was well until I cranked the volume and treble pots, then all hell broke loose. Have spent enough time on it to build another one. just finished building an all tube P-P EL34 guitar amp that I designed (I attached the schematic) but I'm having problems. lbp hmjvkyknt ktsza aoads tafqnip znlr antfh jloovkja fdns mbozqn dmko kutg kdyzbq dja vxf