Hi!
Not a problem with the disagreement, yes there are some interesting paths to take. Its easy to think in the box rather then out of the box. That's the problem few people have tried to build anything using a concept like this. But those that have.....
My own work discovered by accident somewhat parallels this man's work which only enhanced my own. I don't intend to debate the approach which I've seen cause some hard feelings between forum members of other forums but to let you know there are a few DIYers and Engineers using this approach.
I have had a few EE's and Recording Engineers in my own home as well as John here who has many years of listening experience. After hearing what an amplifier built around this concept can do he decided he wanted this path which has delivered his needs unlike many respected commercial offerings he has owned.
In essence it works for him, for me, and others and that's all the counts. If what you do works for you that's all that counts as well and I'm happy for you.
Below is a bit of a commentary from an Engineer that I have followed.
JLH has a Biomedical Electrical Engineering degree from Purdue University.
Posted by JLH (A ) on March 14, 2007 at 14:14:35 on Audioasylum.
"A choke's behavior is to oppose change in current flow. A cap's behavior is to gobble up and store as much current as it can. When the amplifier demands an increase in current the caps initially release some current, but then begin to compete with the amplifier for current because they want to maintain their charge. Then if you have large inductance chokes, they prevent the power transformer from delivering current to the caps because they are opposing change in current flow. This in turn means the more current the amplifier demands, the more the caps compete for the limited amount of current. The result is dampened dynamics because the amplifier is current starved."
The proof is in the listening.
SET12
Hi!
Sorry to the TO for more off topic ...
🙂
I don't see how either of the approaches has anything to do with out of the box thinking...
This is a very incomplete technical explanation of what's going on and shows poor understanding of what chokes do. What is completely missed out is the fact that chokes actually deliver current during the periods when the power transformer/rectifier can't. I could turn that around and argue that the chokes actually help to keep the final cap charged. Also the competing of cap and amp for current is a very questionable argument.
Agreed!
Best regards
Thomas
Sorry to the TO for more off topic ...
🙂
I don't see how either of the approaches has anything to do with out of the box thinking...
This is a very incomplete technical explanation of what's going on and shows poor understanding of what chokes do. What is completely missed out is the fact that chokes actually deliver current during the periods when the power transformer/rectifier can't. I could turn that around and argue that the chokes actually help to keep the final cap charged. Also the competing of cap and amp for current is a very questionable argument.
Agreed!
Best regards
Thomas
Thomas as I said before normally between 85-95 db is where I listen at...I wouldn't call it ear shattering levels I just like to feel the music, so around this level is where the room gets loaded up by the music.
Hi!
Didn't you write somewhere that you measured 2W at the speaker terminals when listening? Or I got that wrong.
If you are listening at up to 95dB then you don't need more power.
Which output transformer is used in your amp? Some SE amps use output transformer with a too low turns ratio which leads to poor damping factor (control) of the speaker. Does your amps have 4 and 8 Ohm taps? If so, try the lower impedance tap and listen if that makes a difference for you. This gives up a little max power in exchange for lower (better) damping factor.
You might also want to check how healthy your 45s are. When the emission drops as they age, so do the perceived dynamics of the amp.
Best regards
Thomas
Didn't you write somewhere that you measured 2W at the speaker terminals when listening? Or I got that wrong.
If you are listening at up to 95dB then you don't need more power.
Which output transformer is used in your amp? Some SE amps use output transformer with a too low turns ratio which leads to poor damping factor (control) of the speaker. Does your amps have 4 and 8 Ohm taps? If so, try the lower impedance tap and listen if that makes a difference for you. This gives up a little max power in exchange for lower (better) damping factor.
You might also want to check how healthy your 45s are. When the emission drops as they age, so do the perceived dynamics of the amp.
Best regards
Thomas
Not sure about which transformers are used it's been a long time since I thought about that, I want to say Magnaquest but that could be wrong. The amp only has one set of taps and I am sure they are 8 ohms. The tubes still measure new so i don't think they have any issues. As I said before there is nothing wrong with the current sound I was just wondering about a PP amp using 45 tubes and what differences I could expect between the two amps other than the obvious power???
Hi!
It is impossible to give a general answer to this as the circuit topology is only one aspect. There are different opinions out there. I'd say both topology can be implemented to provide very good sound quality. In order to predict if going PP will bring what you may be are missing from you SE, you would need to better understand what it is in your amp that causes the 'lack' of authority which another amp had.
Best regards
Thomas
It is impossible to give a general answer to this as the circuit topology is only one aspect. There are different opinions out there. I'd say both topology can be implemented to provide very good sound quality. In order to predict if going PP will bring what you may be are missing from you SE, you would need to better understand what it is in your amp that causes the 'lack' of authority which another amp had.
Best regards
Thomas
Here is part of the key from JLH
"Where does our current come from when the diodes are not conducting? It is my own personal belief that it is a balanced load between the caps draining off and the chokes converting their flux into current. This is were the smaller core and fewer windings on the lower value chokes pays off. The smaller chokes have a much lower magnetic inertia and can convert their flux into to current much faster than a larger choke. The smaller chokes can deliver current demands much quicker, so they tend to make the amplifier sound more dynamic?"
Your approach is what I call a classical text book design approach or in the box, his is what I call out of the box thinking...
But as I said its not my intention to debate. 🙂
SET12
Hi!
My approach is as far from the 'classical textbook' (whatever that means) as yours. Sorry but the claim of 'out of the box thinking' serves as a poor argument. The 'box' is a matter of perspective. From someone else's view you are thinking inside a box, just a different one, 'the low DCR box'.
I am not questioning that your amp sounds excellent. I am questioning the technical reasoning.
Best regards
Thomas
My approach is as far from the 'classical textbook' (whatever that means) as yours. Sorry but the claim of 'out of the box thinking' serves as a poor argument. The 'box' is a matter of perspective. From someone else's view you are thinking inside a box, just a different one, 'the low DCR box'.
I am not questioning that your amp sounds excellent. I am questioning the technical reasoning.
Best regards
Thomas
jcmusic, I am sorry if your question is not being addressed more directly, the short answer is 2W is plenty...in theory. Also, in theory 10W would be better but that is not always the case.
I DO believe you will hear a difference in the nature of the playback if you shift to a PP amp. I'd say most people can hear the difference between PP and SET of a given level of quality. It all means that your satisfaction with your next amp, no matter what that amp is, is not a slam dunk no matter which way you jump. I boldly confess I am resolutely in the SET camp, thats my journey, it might not be yours.
I was trying to offer up my experience as a model because it has been So successful. I grin every day! I can't believe my good luck sometimes...I only had to buy 7 tube amps to figure it out; I built one amp and I won't have to build another, ever.
How far apart are we?. Some things are different. My room is 15 x 15. I listen to Klipsch horn loaded speakers, but I have a sub woofer. I set 8 feet from my speakers (yup I'm near-field and the speakers are in the middle of the walls but it is because of the staris behind the speakers - its a bi-level house, but it all works!). I listen at 86 - 89dB. My amp won't even make 1.6 Watts and it rocks! I have never head it clip. But...La scalas have their 3dB point at 56Hz...My subs use 4th order electronic crossovers and begin at 34Hz, some might think that is a huge gap but again, it works!
YMMV...
That's the thing with stereos at this level, technical descriptions aften fall short of explaining what you hear...unless you listen to quite a few hours of explanations, perhaps hundreds of hours of explanations and still you may not get an explanation you find matches your own experience.
From a pure physics standpoint, 2W should make your room shake. IF it does not satisfy, something is not right. There is the whole chain of events from media to vibrating air...All of it must be managed. It's a lot.
I DO believe you will hear a difference in the nature of the playback if you shift to a PP amp. I'd say most people can hear the difference between PP and SET of a given level of quality. It all means that your satisfaction with your next amp, no matter what that amp is, is not a slam dunk no matter which way you jump. I boldly confess I am resolutely in the SET camp, thats my journey, it might not be yours.
I was trying to offer up my experience as a model because it has been So successful. I grin every day! I can't believe my good luck sometimes...I only had to buy 7 tube amps to figure it out; I built one amp and I won't have to build another, ever.
How far apart are we?. Some things are different. My room is 15 x 15. I listen to Klipsch horn loaded speakers, but I have a sub woofer. I set 8 feet from my speakers (yup I'm near-field and the speakers are in the middle of the walls but it is because of the staris behind the speakers - its a bi-level house, but it all works!). I listen at 86 - 89dB. My amp won't even make 1.6 Watts and it rocks! I have never head it clip. But...La scalas have their 3dB point at 56Hz...My subs use 4th order electronic crossovers and begin at 34Hz, some might think that is a huge gap but again, it works!
YMMV...
That's the thing with stereos at this level, technical descriptions aften fall short of explaining what you hear...unless you listen to quite a few hours of explanations, perhaps hundreds of hours of explanations and still you may not get an explanation you find matches your own experience.
From a pure physics standpoint, 2W should make your room shake. IF it does not satisfy, something is not right. There is the whole chain of events from media to vibrating air...All of it must be managed. It's a lot.
No you probably aren't. I have some scope plots somewhere on my hard drive showing over 20 volts peak to peak of unclipped bass guitar across my 8 ohm speaker. This is coming from my 45 powered SET. Do you believe that my 45's are really cranking out 6.3 watts? The plots are real, how is this possible? The answer lies in the fact that "8 ohm" speakers are rarely 8 ohms, and will go quite high in the low bass region near resonance. My speakers are about 20 ohms in the range I was testing, which works out to a little over 2 watts.
I have a little 45 SET. I run the 45's (or my favorite NX-483's) at 325 volts and 30 mA. The extra plate voltage allows headroom for the average speaker in the bass region. The NX-483's were made before 1929, have been in the amp for almost 10 years and still work great. My amp has been auditioned along side some high dollar equipment and stands its ground quite well, and is often favored by some listeners, especially in the dynamics department. OH, yeah, the power supply uses a $40 transformer, probably has several hundred ohms of DCR but there is a low ESR motor run cap right at the red wire on the OPT. The secret to dynamics is the ability to run right into A2 without distortion and total freedom from overload and recovery issues. AND...I can hold the amp in one hand. I don't have room for huge amps.
BUT, this thread was about push pull 45 amps. I have built a few, but currently don't have a working 45 push pull amp. Why? Tubes. I have about 20 45 tubes. All are quite well used, and most were obtained for $10 each or less. A pair of 45's in class AB2 push pull can deliver 18 watts according to the data sheet. To do this the tube MUST have ample reserve emission capability or the dynamics will suffer and the amp just won't come alive. Most of my well worn tubes will work fine in class A1 or A2 even in push pull, but can't pass the 100 milliamp peaks needed for AB1 or even more for AB2.
I had a fully differential (3 cascaded LTP stages 6SN7's ---> 6SN7's ---> 45's) push pull amp running for a while. With a CCS in the tail of each LTP it MUST run in class A, and roduced about 4.5 watts on 325 volts. It sounded excellent, but I swapped the 45's for triode wired 307A's, raised the B+ to 375 volts, changed taps on the OPT's (UTC LS-57's), and got a great sounding 15 watts.
Attachments
(NO YOU PROBABLY AREN'T)
Dude that's pretty bold of you to come into this thread and make a statement like that without knowing anything other than what you have read!!! Enough said!!!
Dude that's pretty bold of you to come into this thread and make a statement like that without knowing anything other than what you have read!!! Enough said!!!
I may be criticized for this, but I really dislike the way this thread is going:
1 - JCMUSIC is not being clear on his problem: 106dB sensitivity, listening between 86 and 89dB, and saying 2W is not enough, and then attacking George (tubelab).
2 - other newcomer talking about 'thinking ouf of the box', and that just against Thomas (Vinylsavor) who's showing lots of 'thinking out of the box', on, for example, his blog.
I know both George and Thomas can defend themselves, but when I see this sort of newcomers coming, asking for help and then ignore advice, I am afraid people like George and Thomas will just slowly walk away from this forum, and I would hate if that would happen.
best regards, Erik
1 - JCMUSIC is not being clear on his problem: 106dB sensitivity, listening between 86 and 89dB, and saying 2W is not enough, and then attacking George (tubelab).
2 - other newcomer talking about 'thinking ouf of the box', and that just against Thomas (Vinylsavor) who's showing lots of 'thinking out of the box', on, for example, his blog.
I know both George and Thomas can defend themselves, but when I see this sort of newcomers coming, asking for help and then ignore advice, I am afraid people like George and Thomas will just slowly walk away from this forum, and I would hate if that would happen.
best regards, Erik
1 - JCMUSIC is not being clear on his problem: 106dB sensitivity, listening between 86 and 89dB, and saying 2W is not enough, and then attacking George (tubelab).
Listen up dude!!! I never said I had a problem, I never said that I listen between 86-89db read closer and know what you are saying before getting in this thread and making claims.
2 - If George and Vinylsavor feel attacked they can defend themselves you on the other hand should be more concerned about YOU and not others...
Listen up dude!!! I never said I had a problem, I never said that I listen between 86-89db read closer and know what you are saying before getting in this thread and making claims.
2 - If George and Vinylsavor feel attacked they can defend themselves you on the other hand should be more concerned about YOU and not others...
Man! Respect!
These guys you are arguing w/ have been here helping people for many many years.
Looking back at your post history, you have not! You need to sit back and happily take peoples suggestions, whether you agree w/ them or not. Complain to yourself at your computer desk, but don't start arguments here. Everyone is here for learning and help.. keep the attitude elsewhere.
(-maybe a mod could delete this and the past 3 posts)
These guys you are arguing w/ have been here helping people for many many years.
Looking back at your post history, you have not! You need to sit back and happily take peoples suggestions, whether you agree w/ them or not. Complain to yourself at your computer desk, but don't start arguments here. Everyone is here for learning and help.. keep the attitude elsewhere.
(-maybe a mod could delete this and the past 3 posts)
I must apologize for the roll I play in a bit of this confusion. I asserted that jcmusic and I have similar listen levels and put my OWN at 86 - 89 dB. His listening level assessment was 86 -95dB. At 95dB operational parameters are quite different! Sorry all.
Here we go now another unnessacary comment from someone who has not contributed one iota to this thread!!! I am not going to get into this with you mind your own affairs or else kick rocks!!!
John,
No need to apologize if you read close enough this would have been obvious but, most just can't wait to insert their 2 cents and that's where the confusion comes in...
Please move away from personal commentary and let's get back to the technical aspects. A word of advice to those who are new to this forum. Everybody's welcome here, however new or veteran. We expect everybody to be civil. We also value those who have contributed and helped so many users over the years. Let's be nice and try to understand the other people's point of view.
I attempted to explain that simply connecting a scope across the speaker terminals and observing the voltage will not provide an accurate measure of the power actually being delivered to the speaker. Taking the speakers impedance VS frequency curve into account will remove the largest error, but there are still reactive and counter EMF errors. I had to learn this the hard way years ago.
I also attempted to demonstrate that not all 45's are suitable for class AB use.
If my explanation ruffled someones feathers, then I apologize for that. I now have very limited access to this forum (smartphone only) during the day now due to my day job's internet policy, so my posts have become infrequent. I will not be back to this thread.
I also attempted to demonstrate that not all 45's are suitable for class AB use.
If my explanation ruffled someones feathers, then I apologize for that. I now have very limited access to this forum (smartphone only) during the day now due to my day job's internet policy, so my posts have become infrequent. I will not be back to this thread.
Ok guys I am sorry if I was disrespectful to anyone here but, it bothers me when folks who have nothing to do with the current topic get involved just to be typing or voicing their opinions!!!
So I apologize to those I may have offended, and to those that tried to help or had something of value to contribute thank you very much...
So I apologize to those I may have offended, and to those that tried to help or had something of value to contribute thank you very much...