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Bias resistor for source follower driver Post #1 I'm using fqpf2n80's as source follower drivers (direct coupled to KT88 grids). I apply bias to the gates of the 2n80's which are capacitively coupled to the previous stage. I'm currently using 500k resistors to bias the gates of the 2n80's. I'm considering increasing this resistor. My question...

First Valve DIY Project Post #1 Hello to all, and thanks in advance for your help and suggestions. Im getting ready to take a plunge into my first valve project (have done several SS based projects and repaired a few valve pwramps and preamps along the way). It appeared in the September Audioxpress. Its an integrated amplifier that uses 6550s in ...

SEPTOR AT-amp (Anti-Triode) being built Post #1 After some planning the SEPTOR is on its way. It will be a rebuild of some old Erik Andersson(Audio Innovations, Audion etc.) 6B4G PPP monoblocks. After the discussions in some other threads this is what came out. Note that the cathode resistor is substituted with a CCS. The toroid is a Talema ...

Varying 2 tube amp characteristics: SE treble and richness Post #1 Tube amp tone richness: Iirc, if the tube plate load is only 2.5 to 4 times the rp of the tube (vs say 5 6), 2HD and 3HD increase; the lower the ratio, the greater the 2HD and 3HD. Have I got that right? And the open sound of treble from single ended tube amps: Its probably...

Using mains transformer as output transformer Post #1 Hello, I'm thinking how well would a toroidal mains transformer work as an output transformer. You may need to modify the secondary winding to get the correct transform ratio but there should be not much problems in that because in toroid the secondary is on top and extra windings easy to ...

I'm having grid1 current in EL34 Post #1 Hello, With my proto SE amplifier with Elektro Harmonix EL34 there is Grid 1 current going when the input signal is high level and V(gate-kathode) approaches zero. The current starts very abruptly and it seems that EL34 grid 1 will eat all the current I feed to it! How much it can handle? Is this anyway...

anyone ever built a tube mixer similar to the RCA Living Stereo type?? Post #1 I am lusting after one, me being a sound engineer , audiophile, and tube lover.. anyone got schematics or anyone care to build one or advise? Hollow State, interested in you particularly.. ncd IP: Logged

Chasing my Simple SE problem... Post #1 I finally got the courage to try the pair of 6550's again - after noticing a bit of glow I was examining the tube and it sounds like something is loose inside! So, with the knowledge that the one tube is basically bad I decided I would try and chase down the other problem I'm having (caused by the bad ...

VR150 use Post #1 Hi all, Quick ?, I am rebuilding my RH84 (EL84 Pentode SE) and am considering regulating G2. I have never used Gas tubes before, only zeners but have a VR150. So, I am thinking about the VR150 and was wondering if there would be a problem using it with SS rectification for the B+. I have been doing some reading on them ...

Trouble with amp 6V6 Post #1 A tube (6V6) was inserted the wrong way in its socket, the middle guide pin was missing. Now one channel is dead What components can possibly have been broken? Two output tubes 6V6 in triode mode, one 6NIP and one 5Y3. The amp is homemade, not by me, and I dont have a schematic for it and sadly no way to aquire ...

Capacitors and hype! Post #1 A capacitor has capacitance! A capacitor has some Inductance due to it's construction but this is generally negligible? A capacitor has resistance minimal but it's there! A capacitor has Carisma? A capacitor can be full of ******** and cost more than an O/P transformer? Any thoughts and proof!!! Mike...

Post #12 quote: I tip my hat out of respect and appreciation for what he's already published. Amen.

Using mains transformer as output transformer Post #1 Hello, I'm thinking how well would a toroidal mains transformer work as an output transformer. You may need to modify the secondary winding to get the correct transform ratio but there should be not much problems in that because in toroid the secondary is on top and extra windings easy to ...

budget xformer for 829B pentode mode PP (class AB) ? Post #1 What are the low cost PP xformer options for 829B amp in pentode connection (separate g2 VCC) and NFB ? I want to bias it for class AB operation with class A extending to ~5W (normal listening). However I need as much headroom in class B as the tube allows since I'd like to use it with my ...

2A3 SE parafeed with PP-transformer Post #1 This subject has been up in another thread where it drowned in the very interesting PP anti-triode discussion. This one is purely SE in contrary to what I first thought. As L4 a Hammond 150H/8mA can be used. To be able to use a PP-transformer the CT has to be split as the windings are connected...

1st Tube Amp - What to build? Post #1 I'm interested in building my first Class A tube amp to drive full range audio speakers. I've built several solid state amps, and interested in tube experimentation. Question: Is there a great reference design for pure class A, 3-10 watts, and maybe self biasing? Budget is not a problem. There are so ...

Options for replacing EF86? E180F? Post #1 Hi, I'm working on a tube microphone preamplifier where input tube is EF86/6267. I find this tubes quite noisy, some of them are ok from beginning but later become noisy. I could simply change the tube, but prices are quite high and many new tubes are noisy from beginning. Since i love the sound of ...

Trouble with amp 6V6 Post #1 A tube (6V6) was inserted the wrong way in its socket, the middle guide pin was missing. Now one channel is dead What components can possibly have been broken? Two output tubes 6V6 in triode mode, one 6NIP and one 5Y3. The amp is homemade, not by me, and I dont have a schematic for it and sadly no way to aquire ...

Sizing Coupling Capacitors Post #1 I read a good thread here on sizing coupling caps on this forum but I didn't completely follow it and I think I need a little guidance. I have a newly aquired Magnavox 175 amp. It has a pair of 12AX7 phase inverters and four 6V6 in push pull stereo. I think the coupling caps have some room for improvement....