The LS3/5a, or the "shoes box" in general, is the best invention of the last 50 years in home audio!
In general, a compact enough standmount speaker, 2 or 3 ways, is simply the best solution for the vast majority of listening rooms. Big speakers in normal rooms, even worse in small rooms, simply cannot compete.
I see that people attribute too much importance to SPL forgetting other factors that are a least as important, actually more important, than that mere number....
Hi guys !
Following this interesting thread I wondering why grounded grid (G.G.) DC coupled SET Amp is not used often ? , here is my concept schematic ,
Where output power tube V1 can be anything from 45 ,2A3 ,300B , VT4C or .... , and V2 can be any low Rp / high mu triode , or even some pentode , or even substituted with some appropriate mos fet .
Best Regards to all !
Following this interesting thread I wondering why grounded grid (G.G.) DC coupled SET Amp is not used often ? , here is my concept schematic ,
Where output power tube V1 can be anything from 45 ,2A3 ,300B , VT4C or .... , and V2 can be any low Rp / high mu triode , or even some pentode , or even substituted with some appropriate mos fet .
Best Regards to all !
Attachments
Hi Ketje !
Quit contrary I think that GG triode is very good topology for audio ( SET ) , but is not researched enough , for example : what if two parallel strapped 6c45p triodes (V2) drive 2A3 or 300b (V1) cathode ?
There is no more evil Miller capacitance effect included , (at least for output power tube) , and high performance class A2 operation is now possible & is quit different from conventional A2 grid drive .
Hi AatV !
Yes it is basically some sort of cascode ! ,
but I think no extra current is necesary there for normal DHT SET amp A class operation ,
for example G.G. VT4C (211) cathode driven with two parallel strapped 6c45p tubes , common B+ around 1,25KV , 211 cathode voltage and in the same time 6c45p(x2) anode voltage at +75VDC (or even more) , with common plates series current of around 60ma .
Best Rergards !
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When you drive a 300B p.ex.with a cathode follower there is not much hinder from Miller and for A2 an actif pull up.
The problem here is the high cathode impedance witch in turn produce an even greater anode impedance,it makes the triode look like a penthode.
Mona
Agree with that !
Except that except DC coupled CF driver stage we need there one more input gain stage at least , that`s altogether three stage Amp, I try to limit this GG Amp concept to only Two DC coupled stage .
drlomu,
- no clue!
- have we met? the name seems familiar...
- you've met Dennis Boyle? neat... back a few years his stuff was "hot".
no idea what transpired since then
- no idea how this sounds, I thought it was an interesting concept. I worried about the PS voltages being stable enough to keep the operating points/bias from wandering about...
_-_-
- no clue!
- have we met? the name seems familiar...
- you've met Dennis Boyle? neat... back a few years his stuff was "hot".
no idea what transpired since then
- no idea how this sounds, I thought it was an interesting concept. I worried about the PS voltages being stable enough to keep the operating points/bias from wandering about...
_-_-
I have built two stage amps, DCed, with separate supplies, and, totally unlike conventional amps, a SINGLE supply of the same two stage DC circuit certainly sounded and performed the best to me.
It's got some attractive ideas in the design. I was lucky to have an exchange (albeit a brief one) with Dennis and got some pointers on working with the damper diodes in cathode and plate circuits. I never got what I liked from using them in the plates but just the other day pulled out an old amp I did with 6CM3 in the cathode of 6336 and it really does sound good.
I figure an Axiom style circuit would be a perfect project for an L diyer like petavgeris. . .
Nothing...I mean nothing beats the LS3/5A with a 300B SET, if you enjoy music and the size of the room is not an issue. 83dB sensitive + a flat electrical load curve that is 10 Ohms + throughout the mid-range and treble is all you need.
two years later...
I'm about to embark on a two stage dc DHT journey and may well end up benefiting, directly or indirectly from Dr Lowmu's stubborn insistance and long research into low power tube amps. Ive been reading many, many posts and threads in the generous backlog of this fine site and can easily see how folks get mad at each other. Up to an actual flame session I think its good.
I come to this from the perspective of an artist. I did make it into a PhD research program at Cornell so (for an artist) my science skill is pretty good.
I didn't stick with it because my passion to learn was dampered by the need to find grants...ansering someone else's (largely commercial) questions. Blagh! Passion rules!
So I give Jeff a lot of room, a lot of (earned) slack and I see others do too. Its a great group of guys here (and we bleed into some other forums too). Folks give from deep down and I thoroughly honor that. The proper form in science is to duplicate results! So let's have some fun building, building something we can be passionate about in 2016!
Cheers!
I'm about to embark on a two stage dc DHT journey and may well end up benefiting, directly or indirectly from Dr Lowmu's stubborn insistance and long research into low power tube amps. Ive been reading many, many posts and threads in the generous backlog of this fine site and can easily see how folks get mad at each other. Up to an actual flame session I think its good.
I come to this from the perspective of an artist. I did make it into a PhD research program at Cornell so (for an artist) my science skill is pretty good.
I didn't stick with it because my passion to learn was dampered by the need to find grants...ansering someone else's (largely commercial) questions. Blagh! Passion rules!
So I give Jeff a lot of room, a lot of (earned) slack and I see others do too. Its a great group of guys here (and we bleed into some other forums too). Folks give from deep down and I thoroughly honor that. The proper form in science is to duplicate results! So let's have some fun building, building something we can be passionate about in 2016!
Cheers!
TWO YEARS !! I understand. LOL. I just took 37 years to make up MY mind on something really important !!
So I appreciate and understand and appreciate two years, between posts on this hobby-thread. WOW.
Lovely Post - for me to see and read, two years after the thread ended !! . The past is behind us, and we can't change whats already happened. We MUST look forward to 2016, and to the future,. !! Thank you, you are very kind.
The "Passion" you speak of my friend, in any art-form or artistic endeavor goes a LONG way towards achieving extra-ordinary results some seek and love.
I would like to serve you. Please email me, or call me at 660 924-6547, as I have written an unpublished guide on HOW to design such an audio amp, and how to understand what to shoot for in your execution. Also, if you are not too much of a burden, and I suspect you won't be (with lotsa "newbie" questions) I will lead you and / or assist you in any way I can. It will be my pleasure to assist someone like you.
Also, I would like to know the sensitivity of your intended speaker load, to see if a Type 45 Finals may also work OK. ( Its a bit easier to implement, and I am liking my mid-2015 Type 45 DC build a WHOLE lot so far. )
Just contact me when you can.
Jeff
So I appreciate and understand and appreciate two years, between posts on this hobby-thread. WOW.
Lovely Post - for me to see and read, two years after the thread ended !! . The past is behind us, and we can't change whats already happened. We MUST look forward to 2016, and to the future,. !! Thank you, you are very kind.
The "Passion" you speak of my friend, in any art-form or artistic endeavor goes a LONG way towards achieving extra-ordinary results some seek and love.
I would like to serve you. Please email me, or call me at 660 924-6547, as I have written an unpublished guide on HOW to design such an audio amp, and how to understand what to shoot for in your execution. Also, if you are not too much of a burden, and I suspect you won't be (with lotsa "newbie" questions) I will lead you and / or assist you in any way I can. It will be my pleasure to assist someone like you.
Also, I would like to know the sensitivity of your intended speaker load, to see if a Type 45 Finals may also work OK. ( Its a bit easier to implement, and I am liking my mid-2015 Type 45 DC build a WHOLE lot so far. )
Just contact me when you can.
Jeff
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1 YEAR.
I spent 1 year fixing up my acro 20-20. My goal was to lower the idle current in the output tubes while keeping the amp perfectly functional.
After many attempts and tries in error, and with the help of Dave Gillespie, it's now a solved problem.
The only way to achieve this without disrupting the direct coupling is to increase the cathode resistors. 3K to 4K would do it to your taste.
Also starved mode is not that well supported by modern tubes. They add distortion compare to a NOS tube. You may want to use a vintage tube for the 12AX7/ECC83 driver tube, balanced section is a must.
There is a nice thread on AudioKarma on that topic.
Cheers,
Brice.
I spent 1 year fixing up my acro 20-20. My goal was to lower the idle current in the output tubes while keeping the amp perfectly functional.
After many attempts and tries in error, and with the help of Dave Gillespie, it's now a solved problem.
The only way to achieve this without disrupting the direct coupling is to increase the cathode resistors. 3K to 4K would do it to your taste.
Also starved mode is not that well supported by modern tubes. They add distortion compare to a NOS tube. You may want to use a vintage tube for the 12AX7/ECC83 driver tube, balanced section is a must.
There is a nice thread on AudioKarma on that topic.
Cheers,
Brice.
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