Best OPT for 6G15 Standalone Reverb Clone?

 :

10/4/1999 5:59 PM

pumpstein

Best OPT for 6G15 Standalone Reverb Clone? I am building a 6G15 Standalone Reverb Clone and am wondering about the OPT that drives the tank; my question has to do with the wattage of the signal feeding the tank - in a std. BF Fender amp (parallel 12AT7) circuit, the output is only around 1 watt, right? A 6K6 maxs out at 10 watts, I think, and this circuit calls for around 285v on the plate. I've heard of using a Champ OPT to drive a tank - but I don't want to overload the tank, and doesn't a Champ typically put out around 3-7 watts? Is my concern unessecary? Also, the 6K6 wants to see less of an impedance load than the 6V6 (Did I say that correctly?), so I'm wondering how that mismatch would pan out, tone-wise.     Can anyone recommend a good source for a replacement trnasformer? I would appreciate any help.     Also, from looking at the schematic, it seems like it would be easy with a DPDT to switch to a dummy load/line-out from the OPT, so that it could be used as a preamp/distortion effect. I suppose you could even drive a speaker. Sort of a 'Champ-within-a-Reverb Unit'. But that leads back to the wattage question. Anyone ever try that?     Thanks!

 

10/4/1999 6:30 PM

Scott

Keep in mind that the transformer "processes" the wattage (converting it to low impedance), but the power tube is producing the the wattage, and the power tube chosen and its driver circuit determine the wattage produced.     The 6K6 is rated for 8 watts dissipation, but a single ended cicuit is only 30% efficient, so the actual driving power available is maybe 2.5 watts.     A Champ transformer will work fine, or:     New Sensor has a direct replacement Fender reverb trans     Angela Instruments sells the real Fender tranny, I'm pretty sure.     The Hammond 125 series is another good choice as it has multiple taps. Available in different sizes from 3 watts to 15 watts. Available at Angela, Antique Electronic Supply, and many others.     Specs to Look for:   Wattage : 3 watts or better   Primary 8000-12000 ohms   Secondary 8 ohm   Standing DC Current: 25 ma or better     By the way, its best not to copy the cheesy half wave power supply the Fender reverb uses. Make it fullwave and I would recommend a choke also. Building tube stuff is a lot of work and you don't want hum to ruin the sound.

 

10/4/1999 6:41 PM

pumpstein

Thanks so much for the help, Scott - what an age we live in where literally in minutes one can get a reliable answer to a relatively obscure high-tech question in minutes, and for free!     I'll consider your suggestions and let you know how it turns out. I especially thank you for the PS tip - I was already planning on using a FW rect, but am glad to have my hum concerns reflected back.     Very cool! Ampage rocks! Thanks tboy!

 

10/6/1999 12:15 PM
Fj	http://www.hoffmanamps.com/parts2.htm

 

10/6/1999 12:17 PM
Fj	NOTE: The Hoffman H3APA power transformer is now able to power a stand alone reverb unit. See the   TRANSFORMER section and WIRING DIAGRAMS section for more info on the H3APA power transformer.

 

10/6/1999 7:40 PM
pumpstein	Thanks, FJ - I just had my customer order the NOS 6G15 Fender reverb OPT from Doug Hoffman. He was glad to have an authentic part for his clone.     P

 

Page 1 of 1