Either of you guys ever use an 8417?I am waiting for a pair of NOS RCA 8417's to come in the mail.Looking at the data they appear to be fairly close to a 7581A,except they are capable of putting out 100 watts for a pair even tho the max ratings are 35 watts per.They'll take 660 plate volts and 500 on the screen.They have a slightly higher heater current,well about .7a more than a 6L6 or 7581A,but that doesnt worry me,my trannies can handle it.The p/p impedance is 4,200 so its in the ballpark.Wondering if you guys have any experience/obsevations on this tube.First thing I'm gonna try 'em in is a SF Dual Showman I Black faced and pulled 2 tubes on.Its the MV version,so its capable of 135 RMS with 4 tubes,full bore its...well you know.I'm thinking these might make a nice higher powered pseudo triode getup.What do you think?
Question for Mav or T.Wolf
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212Mavguy
Well-known member
I have no experience...but WTF, why not? 
Initial tests with these tubes is not promising.They tested excellent on my Triplett 3444.Put them in an amp and I gotta bias them at 95ma's each just to get out of that crossover notch zone.Gotta put this on hold for now,I just got a couple of SF Supers in to do some major work on.Will get back when I can do some sound tests.These suckas need some serious current to get cooking.
212Mavguy
Well-known member
guessing that you need one hot and high voltage power tranny like they use for 6550's/el34's... like in fender ps160, Schumacher built those ???
there's a guy on eBay named Bob Rissi think his ID is Risson, as in Risson Amps, he's an old fender guy that is retired and builds boutique amps for giggles. He'd be a good info source if you could track him down.
there's a guy on eBay named Bob Rissi think his ID is Risson, as in Risson Amps, he's an old fender guy that is retired and builds boutique amps for giggles. He'd be a good info source if you could track him down.
Yeah,I know of him.Its not really the PT I'm concerned with,its the OT.Like I said,I had to put this on hold for now,but what I've seen so far,its gonna take a beefy OT when I bias these up hot enough to sound good.
212Mavguy
Well-known member
mercury's biggest radiospares...? I have the size one less and it's amazing in detail and bandwidth. Tons of interleaving in those units.
Mercury Magnetics? I'm not really impressed with them.The couple I've put in for people didnt do it for me any more than the Hammond that was in there.I got a few big ones under my bench,when I get to it I'll dig one out.I figure I need something that will pass over 200ma's from what I've seen.The amp I tried them in,and I didnt get to any listening tests,has a big old stock Stancor PT that still gave me 460 v's at 95ma's,but the OT is a 40 watt Vibrolux iron.I was a bit surprised at what I saw because in my Triplett tester,with all other parameters the same,a 6L6 needs -18 bias volts where these call for -26v's.
212Mavguy
Well-known member
Can totally understand your lack of enthusiasm for MM stuff based on your experiences.
I am very pleased with the one I have in my Siegmund, that amp has amazing tones. It is the Axiom radiospares enhanced, one size less than the biggest one. That amp was built to take 6v6's-6550's, and came with a three way primary impedance switch for that OT. I bypassed that switch and hardwired it for kt66's, the most impedance. I think that the more complex interleaving of the RS type is a good thing. Only the first few Bluesbreakers that Marshall made used that tranny type, it was too expensive. The Hammond iron you spoke of is pretty damn good too.
I am very pleased with the one I have in my Siegmund, that amp has amazing tones. It is the Axiom radiospares enhanced, one size less than the biggest one. That amp was built to take 6v6's-6550's, and came with a three way primary impedance switch for that OT. I bypassed that switch and hardwired it for kt66's, the most impedance. I think that the more complex interleaving of the RS type is a good thing. Only the first few Bluesbreakers that Marshall made used that tranny type, it was too expensive. The Hammond iron you spoke of is pretty damn good too.
Dont get me wrong,I aint saying they are bad,just not necessarilly worth the extra $$$ in most instances.Some guys buy them thinking they are going to be such a big improvement over the OT's they have and at first I think its a psych thing,you know,they bought into the hype and paid big bucks,so its gotta be better but after a while they realize WTF.I got a couple of Gerald Webers early "interleaved,paper bobbins" and they are great,but I got them for free,I dont think I'd pay the big ticket when most Hammonds will get you there for half the price.In a higher quality boutique amp like your Siegmund of course you want the best so I can see where the Hammond or such would be like "downgrading",even if the lower priced iron sounded okay,it would always be in the back of your mind,what if... and you know when it comes to tone thats half the battle,always wondering if it could be better.
212Mavguy
Well-known member
"and you know when it comes to tone thats half the battle,always wondering if it could be better."
Isn't that why you are doing this project in the first place? The top end Hammond stuff is good at any price. Even better, the price is a great value. Looking forward to seeing some amp porn some time to the future.
Isn't that why you are doing this project in the first place? The top end Hammond stuff is good at any price. Even better, the price is a great value.
Looking forward to seeing some amp porn some time to the future.Well,I really didnt have a "build" planned around these,but you never know.I just bought them out of curiosity,to see how they would sound as a 6l6 type sub,"wondering if it could be better".As for the "amp porn",dont know how to post pics here,but I have figured out how to email them.Computers still scare me.212Mavguy said:"and you know when it comes to tone thats half the battle,always wondering if it could be better."
Isn't that why you are doing this project in the first place? The top end Hammond stuff is good at any price. Even better, the price is a great value.
Timbre Wolf
Well-known member
Late to the party... but I'll provide a distant echo of Mav's eloquent synopsis :lol:212Mavguy said:I have no experience...but WTF, why not?
