|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
71.212.196.9
In Reply to: RE: Questions about 6BG6G amp build (schematic) Grommes 216BA posted by Michael Samra on May 23, 2017 at 03:07:41
Thanks very much Mike. (we go back about 10 years, I reckon). This Williamson circuit is reminiscent of my old Heathkit W5Ms (now sold), which I meticulously restored. It used 5R4s which I understand require smaller 1st cap. Also I am running out of room underneath this monoblock chassis. I plan to use 5R4 to drop B+ a bit (but have MANY diff 5V rectifier tubes). I'll do 30f film.Honestly did not know increasing choke would "kill dynamics and roll off the high end". I use 10H - 20H in preamps, but that's a different animal. Schematic for this calls for 2.6H. Anyone want to trade some good 6H and 9H chokes for a pair of 2-3H chokes? :)
Speaking of the Hk W5Ms, I switched the 12AU7s in those to 6CG7s - there was no benefit whatsoever - I may have even lost something. What if I plugged in 12FQ7s (which I have) or even 12BH7 (have dozens) to the signal tube positions? There isn't room for 6SN7s.
Pic shows my chassis layout test. (A choke sitting where the OPT will go.)
Thank
Petein Denver
Edits: 05/23/17 05/23/17Follow Ups:
i would like to see the explanation for HOW a power supply choke can kill dynamics and roll off the top end. Anybody? The power supply should be as rock stable as possible. Anything that affects that stability is going to affect sound quality.
What I was saying was,if the choke is totally miscalculated for circuit,it can change the impedance of the power supply and how it relates to the load that it is feeding.This can cause loss of dynamics and or freq response.It happens mostly at lower frequencies like 120hz.
I figured this out years ago when I took the choke out of a Citation 2 and put it in the Golden tube SE-40 and we are talking two amps that draw close to the same current. When I put the choke from the Deuce into the SE-40,everything got muffled and dynamics just washed out. The Choke in the SE-40 was a bit larger,but the choke in the Deuce was like .7hy but being both amps had plenty of capacitance of either side of the choke,I didn't think it would be a big deal.
As I have said,I didn't mean to imply that it wouldn't work however,just throwing a high inductance choke that looks impressive into a power-supply can cause issues that one might not expect.That's why I asked Pete if it was the one already designed for that circuit.
I'm one of these people that believe in measuring the basic fundamentals when you make any electrical changes.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
In preamps,current is much lower of course.A 6hy could work just fine if you don't saturate the core by drawing excessive current and Heathkit was able to execute that circuit quite well.
There are a couple things at play here.One,Heath is using an opt trafo that is almost double the impedance of the typical 6L6/KT66 circuit.Most KT66/6L6 PP circuit work in the range of 6.6k.The 16309 trafo is like 11.9k and the 16448 is like 10.9k.The Heath choke is 150ma so that is adequate for that circuit.The circuit is also UL and all these things play a role in that wide bandwidth,low distortion circuit.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
NT
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: