From: Josh (rockettone@msn.com) Date: 10/18/2000 6:37 PM Subject: EL84s in 5E3 deluxe I have been contemplating fabricating some adapters to run El84s in my tweed deluxe-ish homebrew amp. has anyone tried this? what kind of sound changes should I expect? my amp has lower coupling and cathode bypass(preamp) caps than a 5E3. it also has a 3 band tone stack after stage 2 and a long tail PI. I am using an adjustable resistor for the cathode resistor for the power tubes, so it would be easy to drop its value to about 130 ohms. the PT has plenty of current for plates and heaters if necesary(not sure if EL84s have more or less current draw). anyway, I like the basic sound of the 6V6s when played clean or slightly overdriven, but higher gain sounds are kind of flubby and "looser" than I would like. the EL84s should be a lot better in this regard, right? I have always heard they don't sound so good clean but they have a nice tight, midrangy character when driven hard. thanks for any input, Josh START NEW THREAD REPLY PREVIOUS LIST Read 73 times From: Morris (mitchellm@gosaints.com) Date: 10/18/2000 8:19 PM Subject: Re: EL84s in 5E3 deluxe Just for the record, an amp with a tone stack and a long-tailed pair PI is nothing like a 5E3 Deluxe. EL84's will sound less flubby when overdriven as compared to 6V6's. I wouldn't say that EL84's sound bad clean though. Look at some schematics for the newer Fenders that use EL84's for ideas; they sound much closer in design than a 5E3 for what you are doing. START NEW THREAD REPLY PREVIOUS LIST Read 66 times From: Josh (rockettone@msn.com) Date: 10/18/2000 8:34 PM Subject: Re: EL84s in 5E3 deluxe Yes, i know, Its no where near an *actual* tweed deluxe, with regards to the preamp and PI. but I refer to it as such because it the basic style of the amp and uses the power supply and output section. it was also the platform from which I built this amp. I don't wan't to build and amp or modify this one, just wondering how the tube switch will change things. Josh START NEW THREAD REPLY PREVIOUS LIST Read 44 times From: Josh (rockettone@msn.com) Date: 10/18/2000 11:10 PM Subject: Re: EL84 Sovtek or EI? Incedentally, which current production EL84s are best Sovteks? Yugoslavia? I really have no clue as I have been a 6L6/6V6 guy my entire life. thanks, Josh START NEW THREAD REPLY PREVIOUS LIST Read 37 times From: Bruce (Missionamp@aol.com) Date: 10/19/2000 2:47 AM Subject: Re: EL84s in 5E3 deluxe ...run El84s in my tweed deluxe-ish homebrew amp. has anyone tried this? what kind of sound changes should I expect? my amp has lower coupling and cathode bypass(preamp) caps than a 5E3. it also has a 3 band tone stack after stage 2 and a long tail PI. I am using an adjustable resistor for the cathode resistor for the power tubes,... It always tickles me when I read about you guys building 5E3 clones... with EL84s, all 12AX7s, BF tone stacks, long tail pair drivers, etc etc... ha ha. What you have is a fictional non vibrato cathode biased BF Deluxe/Princeton there Josh! Any resemblence to a tweed Deluxe is purely coincidental and totaly irrelevant. Your preamp might blow the tops off a pair of EL84s. Bring it way down when using EL84s. Bruce START NEW THREAD REPLY PREVIOUS LIST Read 30 times From: Chris B (Bradaack@cs.com) Date: 10/19/2000 3:28 AM Subject: Re: EL84s in 5E3 deluxe Bruce has a point there... I tried the same thing, except I kept the entire preamp and PI exactly like a 5E3 deluxe. Too much output. I had to replace the plate and cathode resistors on gain stage 2 with a 470k and a 4.7k to lower the drive to acceptable levels, and may lower the first gain stage as well. Also, you can't just switch tubes. You have to change the cathode bias resistor on the output tubes too. But you probably already knew that. Chris B START NEW THREAD REPLY PREVIOUS LIST Read 21 times From: Josh (rockettone@msn.com) Date: 10/19/2000 4:25 AM Subject: Re: EL84s in 5E3 deluxe Okay, Okay, geez. I won't use the much revered term "5E3" so lightly anymore. like I said, I have a habit of calling it that because that's what I started with. this preamp is significantly "turned down" from a real 5E3 though, I changed the coupling cap to .022 and the cathode bypass caps are now 1uf. there is also a resistor of 500k following the vol. pot. So, you're saying EL84s can get flubby like 6V6s if the preamps too hot and pushes them excessively? Josh START NEW THREAD REPLY PREVIOUS LIST Read 3 times From: Bruce (Missionamp@aol.com) Date: 10/19/2000 6:52 AM Subject: Re: EL84s in 5E3 deluxe So, you're saying EL84s can get flubby like 6V6s if the preamps too hot and pushes them excessively? Josh Yeah! All the smaller cap ideas are good but, since you are also using a PI/driver with gain, you'll be able to swing about twice as much voltage as needed to turn an El84 inside out. Hook it up to a dummy load and crank the amp with a voltmeter across the cold side (no B+) of the PI drive caps and see what kind of AC swing you're getting. Most RC coupled EL84 amps will cave in at about 30vpp-34vpp. Other then helping to isolate the volume control from the next stage, your series 500K resistor won't do too much to drop voltage to the next stage. It will increase the grid load resistance on the next stage causing the amp to be a little noisey when the volume is turned down. Normally that grid is at ground potential when the volume pot is at zero... you are still holding the grid up by 500k when the volume pot is zero'd. If you wanted less signal to the next stage you should have the 500K on the wiper but ground the other end of the 500K and still take the signal from the wiper to the next stage as normal. Bruce