Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: p2pAmps on January 06, 2019, 09:09:36 am
-
This is something I have been meaning to build for awhile now, a cool hifi amp. Sure glad I did as it sounds amazing. Sporting 4 KT120s, 5AR4, and 3 12AU7s... Nice change of pace
(https://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/5c1eff7303ce64637db73342/5c285499562fa795d87ba45d/1546146971937/IMG_2575.jpeg?format=2500w)
(https://static1.squarespace.com/static/56fbe87462cd94ff6ec9d02c/5c1eff7303ce64637db73342/5c2854944fa51a03a88bb2ad/1546146967683/IMG_2565.jpeg?format=2500w)
-
:thumbsup: :thumbsup:
-
That's remarkably cool! What a fantastic project! THANKS for sharing your success with it. :thumbsup: :thumbsup:
With respect, Tubenit
-
nice. but why is choke on the left side anchored with only one bolt/nut?
--pete
-
:thumbsup: :thumbsup:
amazing workmanship, and the octals for speakers, killer!
using DC filaments? I see a bridge under but a tube rec above
-
:thumbsup: :thumbsup:
amazing workmanship, and the octals for speakers, killer!
using DC filaments? I see a bridge under but a tube rec above
Hey Shooter, yeah, DC filaments for sure. The small circuit board is a TDR for a slow start should I decide to use a SS rectifier (no bridge). These amps are very cool and give a McIntosh a serious run for the money
-
nice. but why is choke on the left side anchored with only one bolt/nut?
--pete
I know huh LOL. Thats the way the chassis was drilled and I didn't want another hole in the top so I let it sit the way it sits. It's not causing a problem but does kinda rub me the wrong way too :)
-
BTW, those two switches in the middle are triode/pentode switched, kinda cool. I'm using it on the triode ultra linear mode which is more powerful and sounds good for the stuff I'm listening to.
-
so what's the amp using to drive the air
-
so what's the amp using to drive the air
The rest is a McIntosh MX130 pre, Marantz 6300 turntable, and a set of JBL 120ti speakers. Next I will build a tube pre and a DAC...
-
Big time soup up of a Dyanco. Tube pre. I go back and fourth. I have a very nice Marantz type tube pre I have built. I have too much junk anyway. This looks great. Where did you source the chassis?
-
don't know if his is from the same source, but you can get one here (http://triodeelectronics.com/st70chassisnew.html) ed.
--pete
-
That is too cool and affordable considering some of the extreem cork sniffer kits and finished products out there.
I hope this isn’t too much of a hijack... I went on their website and noticed an auto-bias circuit. How does this work?
Jim
-
@Jim: https://forum.audiogon.com/discussions/quot-fixed-quot-bias-versus-quot-auto-biasing-quot
Another dynaco-type kit source: http://www.tubes4hifi.com/bob.htm
-
That's a really nice amp.. did you get the driver cover for it too?
-
@Jim: https://forum.audiogon.com/discussions/quot-fixed-quot-bias-versus-quot-auto-biasing-quot (https://forum.audiogon.com/discussions/quot-fixed-quot-bias-versus-quot-auto-biasing-quot)
Another dynaco-type kit source: http://www.tubes4hifi.com/bob.htm (http://www.tubes4hifi.com/bob.htm)
JJ thanks for that. And that is the site for P2P’s amp. I was just wondering how the auto bias works. It sounds like automatic antenna matching for my Ham radio with servos. I was just wondering how the comparative circuit works? As someone who does “atmospheric biasing”, I don’t know if I could trust that!!!
Jim
-
http://www.tubes4hifi.com/bob.htm#ST120
-
That's a really nice amp.. did you get the driver cover for it too?
Nah, I kinda like staring at those KT120s! :icon_biggrin:
-
Jim, I'm not sure the guy's right. Some hi-fi purists opt for a voltage regulated bias supply. That keeps the bias voltage constant regardless of B+ sag. This would result in cold bias under strong signal conditions. So they might also regulate the B+ supply. This results in a lot of statistical performance claims, but I don't know if there's a real tonal difference.
Some hi-fi purists don't like B+ or bias voltage moving around on principal. I think they claim it will modulate output power causing a tremolo affect which is not true to the original signal. Maybe they're technically right???
FWIW I think McIntosh used a more passive feedback circuit to eliminate the need for bias adjustment.
-
(http://www.tubes4hifi.com/M-125-2run.jpg)
wondering if bob's amp melted down. the one monoblock on the right is not happy in the pic.
--pete