Yes, I know about Joe. I do things a bit differently.Joe Roberts also prefers using a Altec 414 as full range with a Altec 802 in a WE 32 horn. No crossover. I think just one simple cap.
Maybe you should also make an assessment of this build using the Tuttle-designed, Fulton-modified, dual-mono Bravura that, until very recently, you had been using and in love with for the past forty years.Thanks, good question !
I currently have a Trevor Lees cascode 12AX7 phono preamp, no line stage, sometimes a DIY passive ATTENUATOR. I own about 12 to 13,000 LPs collected since 1960 . Have plans for my own 12AX7 preamp build, with SHUNTS, DCed, and Final Filters, maybe in mid 2022.
Also own a Pioneer ELITE BDP-09FD 31 pound bluray player, for CD playback. My only digital.
For amplifier evaluations the last five years, and designing by ear, I run the BDP-09FD directly into an amp, one set of interconnect cables and RCA jack interfaces, full signal. This eliminates any ATTENUATOR and a second set of interconnects and RCA jack interfaces needing to be in the circuit.
Yes, it is loud, but ' have no neighbors to worry about. Just my own hearing damage to consider.
Jeff
Have you actually given thought as to whether a two-stage dc-coupled 12AX7-based preamp with "passive" RIAA equalization is even feasible ? If you have, perhaps you could share a sketch which illustrates a proposed conceptual design topology which shows some idealized operating points for the two tubes. Also, in 1960 you were just out of middle school, which leads me to wonder how you were able to afford LPs which were easily $3 each at the time. Lastly, with a collection of thirteen thousand LPs, how are you able to store and keep track of them all?Thanks, good question !
I currently have a Trevor Lees cascode 12AX7 phono preamp, no line stage, sometimes a DIY passive ATTENUATOR. I own about 12 to 13,000 LPs collected since 1960 . Have plans for my own 12AX7 preamp build, with SHUNTS, DCed, and Final Filters, maybe in mid 2022.
Also own a Pioneer ELITE BDP-09FD 31 pound bluray player, for CD playback. My only digital.
For amplifier evaluations the last five years, and designing by ear, I run the BDP-09FD directly into an amp, one set of interconnect cables and RCA jack interfaces, full signal. This eliminates any ATTENUATOR and a second set of interconnects and RCA jack interfaces needing to be in the circuit.
Yes, it is loud, but ' have no neighbors to worry about. Just my own hearing damage to consider.
Jeff
Drlowmu, what is the gain of your power amp in dB? Is it like 26 dB?
Two more interesting tubes apart from F2a, EL12 and RS1003.
I too love simple 2 way speaker setups… They can be cleverly, well executed using high sensitivity drivers.
Your statement " Knowing things technically, certainly does not mean you are any good at all in audio, and that you approach audio " playing with a full deck " may well be true. However, it's only because of my technical knowledge that you currently have a working Tuttle-designed, Fulton-modified dual-mono Bravura preamp that that you have been using and in love with for the past forty years.Dear Yogibear,
Cool post. To discover and use the best sounding tube amps possible, you need to own and use 100 dB speakers , with a large radiating surface ( another way of saying, using a 15 inch or larger woofer ) , as the minimum sensitivity.
Actually, 101 dB and up, with a large radiating surface is even better. ( No small radiating area / highly efficient / single drivers , eg: Lowthers )
I don't think you guys do that.
If not, you have the wrong speakers to be making listening decisions for ultra audio !!!
So Yogibear, you will do a post, as your's above, discussing eight Watt tube amps !!
Speaking frankly, I would tend to discount all your three tube suggestions, if you are not using 101 dB speakers for evaluation, and ..... if you are also using a conventional tube amplifier's power supply.
This is where we differ - and we will obtain different results.
As I lay in bed last night, I kept thinking to myself, how can ANYONE ever be in the tube audio, the high performance game, and not have GTO caps in his ( or her ) power supply ( bypassing caps to the Finals, and also on the speaker crossovers ) ??
Also, I ask myself, how could they have any performance when using power supply chokes " by the book " that meet critical inductance, at the expense of higher DCR ??
So there is where I THINK we are Yogibear.
I do not know what Perm runs, but he too is discussing F2a tubes. You guys are both VERY decent human beings, and honest. Someone like Perm also knows much more than me technically, anyone can easily tell.
Knowing things technically, certainly does not mean you are any good at all in audio, and that you approach audio " playing with a full deck ". Dr.Gary comes to my mind actually, L.O.L., all his life, as THE PERFECT example of this.
If you folks had your best performing amps, in my modest sized living room, powering my VOTT A7-8s ( with 515Bs and 802s ), I would expect that the new 6005 effort ( as soon as I finish it and it breaks in ) would easily and thoroughly outperform any amps you brought. L.O.L., this 6005 amplifier uses a small 7 Pin, ten dollar, twelve Watt plate rated vacuum tube. Not so - not the case, if I was visiting in India, results might likely be opposite, when listening on someone's 97 or 98 dB speakers !!
I would 100% love to remain respectful and on friendly one-on-one terms with both of you. We all chase the same dream !! But at this moment, I sense our personal experiences, backgrounds and approaches in audio, are somewhat unique and different from each other !!
Do you, and can you " get " what I am trying to say, and are you able to accept my thoughts without malice - and openly continue to " talk audio " ?? I sure hope so !!!
Let us openly continue to DO things together Yogibear. For all of us tube amplifier enthusiasts, I would like to think, most likely, " the best is yet to come " !!!
Personal best to you,
Jeff Medwin
I'm kind of with you here DrGary. I have followed this thread on and off and while drlowmu clearly loves his hobby and builds his amps with incredible detail, the technical information being offered is seriously lacking even basic electronic knowledge. And the fixation on these mundane details like a #4 capacity wire lug. If that's what you need, fine. If that's all you have in your parts bin that evening, that's fine too. But it's hardly a revelation in audio product design.With regard to your accusation that I have been trying to discredit you, I would suggest that you do an excellent job at discrediting yourself, and that you do not need any outside assistance from me. For example, forum participant Prem just asked you "what is the gain of your power amp in dB" and your reply was "I do not ever precisely measure or even know the dB". Furthermore, if that admission of technical ignorance and incompetence weren't bad enough, you then went into a totally nonsensical commentary about mu this and mu that and some sort of meaningless "jump factors" which have no relevance whatsoever to the very simple and basic technical question that Prem asked about an amplifier that you are presumably looking to build and sell to others.
But keep in mind drlowmu advocates the bypassing of the AC line fuse with a switch in a previous post. If I did that I too would be leery of a wood chassis!Hmmm... I do not want to inflame, to turn the world around and stir up controversy.
Right: wood cannot and would not be acceptable for industrial use, because of its weakness (it burns!) but it is far superior to steel as a chassis in all respects... but this is ONLY my opinion; do not expect to be believed and I really do not want a debate/argument pro/against it.
It is just a personal approach and a way of doing things!
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Jeff, I do not want/need advertising, neither do I want to argue, or pollute your topic.
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Looking forward to hearing experience from you, after such a complex, over-engineered tube amplifier (well, 6 of them, afterall!).
Then we can then talk about acoustics, enclosures and tube amplifiers in other topics.
I am only glad to have found a builder with such a passion and who works down to the ultimate detail, just like you.
With friendship...
That's nice. When did you have that ??Below is just one example of various builds I have done. The FR is 100dB and woofers are 97dB. Another build I did with 95 to 100dB FR and 103dB woofers. FR are 8” to 15” and woofers have always been 15” and many times two each side.
These have played with as little as 0.5 watts of tube power.
I have very simple and very short chain of music reproduction. I can compare every single tube amp with excellent individual impressions.
Hopefully soon, I will have a groundbreaking setup (in fact two) to swap and compare any speaker or amp with the other.
At the end of the day, what matters is not what or how you do it but what you hear and the non stop pleasure it brings forward.
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I'm kind of with you here DrGary. I have followed this thread on and off and while drlowmu clearly loves his hobby and builds his amps with incredible detail, the technical information being offered is seriously lacking even basic electronic knowledge. And the fixation on these mundane details like a #4 capacity wire lug. If that's what you need, fine. If that's all you have in your parts bin that evening, that's fine too. But it's hardly a revelation in audio product design.
And I don't get these 1500v rated capacitors. These are actually commutation capacitors for VFD motor drives, large UPS systems, and enterprise class Solar inverters. They have no benefit for HiFi audio applications. But hey, if you want to use them I guess they will work. But a Sprague Orange Drop or a good quality electrolytic cap will work just as well and be a lot more reasonable size plus a lot cheaper.
I also find these statements that all other amplifiers are designed wrong and that this is the only way to build a high quality audio amplifier rather arrogant! There is no "best audio amplifier" because there are numerous other factors that influence HiFi audio reproduction starting with speakers.
There is no "best audio amplifier" because there are numerous other factors that influence HiFi audio reproduction starting with speakers.
Forget about trying because there is no way to understand the absurd and nonsensical claims of a lunatic.I don't understand this at all. Your B+ is no doubt from a center tapped rectifier topology. Your filaments are hopefully either center tap grounded or have a phantom center tap made from two 100 ohm resistors to ground or a hum pot centered to ground.
Either way you will still have a 180 degree difference from either winding end to ground?
What difference does it make in reality? I think that's the reason why the classic manufactures, current manufactures, and DIYers don't bother with it.
But if you think you hear a difference, going through this doesn't hurt anything either.
Yes, every transformer used - has real center taps.I don't understand this at all. Your B+ is no doubt from a center tapped rectifier topology. Your filaments are hopefully either center tap grounded or have a phantom center tap made from two 100 ohm resistors to ground or a hum pot centered to ground.
Either way you will still have a 180 degree difference from either winding end to ground?
What difference does it make in reality? I think that's the reason why the classic manufactures, current manufactures, and DIYers don't bother with it. The only time I worry about POWER transformer winding phasing is when I parallel dual primaries or secondaries. There it matters and can destroy the transformer if wrong.
But if you think you hear a difference, I guess going through all this extra work this doesn't hurt anything either.
Still not quite clear because if one side of the center tapped winding is going positive, the other side will be negative with respect to the CT or ground. And on the scope is it dual trace or are you using external sync? In which case one phase is the reference and the other phase is being evaluated? How do you know your reference phase is the right phase?
Or do you simply mean getting all tube filaments of the same type on the same phase. Let's assume the output tubes use pins 4&5 for the filament. Are you just making sure say all pin 4 are positive and all pin 5 are negative in this example? Now I have heard of some builders doing that. Still not sure it makes any difference, perhaps it might in a phono preamp or other high gain / low noise application.
..... Just have a good enough piece of equipment, and A-B it. Its so very simple !! If you can not hear any difference, your hearing is AOK, but your audio system surely is not. !! ( Not revealing enough. ) .......