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So far I haven't experienced microphonics. Here's a couple of clips. On this one I just tapped on the tubes and cab.Quote:
Originally Posted by RonSSS
DSCF4114 | Flickr - Photo Sharing!
This one I clicked the pause button on and off a few times. I can't hear anything. And this amp is dead quiet. There is a blackness behind the signal that I haven't heard before.
DSCF4115 | Flickr - Photo Sharing!
That's cool. Thanks.
My amps have no global feedback, perhaps the reason? And, I have the Svetlana "sparkler" tubes, maybe also part of the problem.
How hard do your amps run the 300B? Plate volts and current? Or simpler, plate dissipation?
I just might pick up a quad of those tubes.
BTW...I really like Lyle Lovett's Large Band CD. Very nicely done to boot!
Ron
Plate dissipation in this circuit is 20W, or 50% below maximum rating.
The B's will last forever.
Forever is good. It puts out 1.5W SS into 8 Ohms. Into my 604s which are 16 Ohms I'm getting about 50% more. Of course, more would be nice, but that's not what this system is for. I'll have my 15W amp and A7s when I want to rock the casbah. But even at 2+W, into a 99dB speaker you can get pretty loud.Quote:
Originally Posted by RonSSS
After a day and a half of trying to track down why one amp wasn't working, with Bruce's help I found out I had a bad preamp capacitor that was basically shorting Pin 1 to Pin 7. The eerie thing is I replaced it last night with another one and the 2nd one was bad too!!! What are the odds.
Well they are burning in nicely. The sound is intoxicating. These amps do for music what salt does for a recipe. All the flavors are there already, it just brings them out so we can taste them. Yum.
SE doesn't have to be wimpy.
http://www.pentalabs.com/pdfs/833d.pdf ;)
Now that's what I'm talking about. A little research revealed that the Lumley Metropolis monoblocks actually used this tube...but it dissipated 1800W in just heat. You would have to run your A/C in the dead of winter.Quote:
Originally Posted by mah
Quote:
Originally Posted by mah
Hello,
You certainly don't need a "big" tube to have a non-whimpy amp. What is needed is a proper power supply, and a small tube can easily rock on a Altec system. In the end, we all listen to a modulated power supply. How good is that power supply?
Most audio power supplies are very-much inadequate, so people compensate for that by using bigger tubes, to make up for their poorly designed, poorly wired, poorly power supplied tube amps. However, if you do it right, it can be done with a single 2A3 or maybe even a single 6AQ5, triode connected. Little tubes can and do often sound better than bigger tubes, and the DHT Type 71A and Type 45 come to my mind.
Little tubes, well implemented, are NOT whimpy at all and can have fantastic bass, PRAT, etc. I have such a DIY amp sitting in my living room powering EV12-TRXBs right now, 1.4 Watts output with a 18 pound purpose-designed power transformer. Wimpy power supplies are whimpy. Poor executions are whimpy. And all such amps are musically uninvolving to hear.
LowOhms
Since this is the "show me" thread....would you be willing to post a picture and schematic of your amp?Quote:
Originally Posted by LowOhms
Jeff, I'm also a user of low powered amps but regardless of how perfect the power supply is, the power and therefore the volume that the amps will play at is restricted. Even with high eff speakers you can't reach party approved levels with a couple of watts. I use either model 19s or 604-8Gs in 620 style cabs so the efficiency is there. If you have dynamic music with realistic peaks, you're going to be limited by the low power of 2A3 amps. Don't get me wrong, I use them but I also have other amps for big music and party days.Quote:
Originally Posted by LowOhms
Attachment 2061Quote:
Originally Posted by Alien_Shore
Sure, give me a little time to snap a photo or two. Amp is 95% done. My typical power supply to Finals is shown in step-test simulation, attached. As you can see, it settles in 22 mS, and has less than 10 Ohms DCR spread over L1 and L2.
LowOhms
- - - Updated - - -
Quote:
Originally Posted by zelgall
Zelgal,
No doubt about your report. I fully believe you. But you are guessing about "how perfect" sounds, because I believe you have never heard it. You most likely have a "typical" 2A3 or low powered amp, and yours won't play at all as I describe. Its correct, its not just one thing, the power supply, that matters, everything matters, and I have pointed out the three biggies, lay out, wiring, and supply.
For the last 5 years, I have heard properly power supplied, wired, executed SE 2A3 amps on GPA 604s, and they do just the opposite of what your amps sound like! They don't leave me wanting for more. I HAVE DEMOED THE SYSTEM at RMAF, AND HEARD THEM IN MORE THAN ONE VENUE.
LowOhms
Neither have you. Please cut the bull and stick to reality. No human has perfect ears. You may have heard what compensated for your ears adequately.Quote:
Originally Posted by LowOhms
How do ageing audiophiles maintain their powers of aural discrimination as their hearing degrades with age? There are hi-end audio reviewers who are no Spring-chickens.
Edison used to chomp his teeth down on his player to transmit the vibrations through his teeth and jaw into his skull.
porn mags start coming with braille pictures
Despite the url, this is not xxx-rated
Girls with Vinyl Records
Hi Jeff. Two L's. It's not my name but I've used it here for years.Quote:
Originally Posted by LowOhms
Regardless of how many amps you've heard, there are others that are better.
I was making amps when I first saw you in Sound Practices. I know you've had a lot of experience with building and listening to top rate systems but that doesn't mean I've been sitting on my ass for 20 years. I've also been refining my system and learning about tube amp design.
I appreciate that you have strong opinions about your friend's products and methods but there's more than one way to sonic bliss. I'd say that I've surpassed the mainstream sound by a fair margin as I'm sure you have. I couldn't say that my amps sound better than others but nor can anyone else. If you haven't heard it personally, you don't know what it sounds like.
Different directions with the same destination.
Kyle.
Quote:
Originally Posted by zelgall
Hello Zelgall,
Yes, I noticed the single L but I didn't have the time earlier to do an edit. Sorry. Two Ls can also mean L1/C1/L2/C2, my favorite filter design to the Finals.
When you post that your SE 2A3 amp can not play your Altec speakers satisfactorily to "party or boggie" I immediately obtain a pretty strong hint as to what you are building. That is why I counter-posted to you Zelgall in the first place.
What I want from a low powered SE tube amp is ALL-OUT PERFORMANCE, the best possible result that can be had, within reason of my budget.
You say " Different directions with the same destination."
Respectfully Zelgall, I don't believe that you and I presently share same destination .....
Your destination, from what I read that you posted, is "an acceptable result and well above average playback."
My destination is to have the best possible result, all-out audio performance.
These are not the same destinations, are they?
I fully believe there is only ONE optimal way to get the best result.
Additionally, I think I have found out what that is, what I now a days call a "modern" power supply. This came about as a result of 30 years of myself and another individual experimenting with tube amp power supplies.
Zelgall, have you ever read the chronological postings I complied from the AA Forum by Messers John Swenson and John L. Hasquin, two graduate E.E.s?? It is their direct DIY build and listening experiences with "modern" supplies. Both these guys are very well respected in audio.
If I never sent it to you, you should read it, and you would understand better what I am trying to communicate.
One would NEVER say "different directions to the same destinations" after reading their own posts.
I would be very happy to send them to you, ( or any Altec Forum Member to review at your convenience ), as it outlines the basics of what I call a "modern" power supply. My email address is drlowmu AT gee male.com.
I like what Winston Churchill once said " I am very easy to please, I am always satisfied with the best there is" ... That is fully what I want in 2013 for a low powered audio amp to power Altec type speakers Zelgall.
I don't hedge, I tell you straight-out my goal and objective. I can back it up too.
Alien_Shore, photos tomorrow.
LowOhms
Hi Alien_Shore,
Here is my own "unique" 2013 DIY design / work in progress, a 49 pound stereo DC coupled two stage amp.
Very direct, dynamic and transparent sounding.
Its a half of a triode 12AY7 low noise microphone driver tube, directly coupled to a 6AQ5 / 6005. This is a ("dynamite" because of tiny-spacing) pentode tube, that is triode connected. Output transformers are delicious Magnequest DS-050s. Zero Negative feedback.
Power output is 1.4 Watts but this amp has about a 400 Watt power supply supporting it, and is uniquely wired, with multiple paralleled spans of Kimber Kable TCSS, each amount determined by ear, for maximum bandwidth and transfer efficiency - hence dynamic contrast ability, which I believe is a first in audio.
Rectification is by dual directly heated 5V3As, and the custom designed ( by me ) power transformer sports an uber-low DCR of only 8 Ohms, ( end to center tap ) on the secondary. My power supply's winding wire can do 900 mA. but the entire amp idles at 60 mA. or less. L1 choke is only .8 Ohms DCR and L2 choke is only 6 Ohms DCR...... compare that DCR with anything else you have ever seen on a tube amp schematic !! This power supply delivers energy in the time of the music. The Finals supply is VERY fast settling, under 50 mS. ( See earlier PSUD simulations as my example .)
The front end B+ has under 2 mVAC of ripple, and it operates with a KISS one-part shunt regulator with no feedback. There is a final L/C filter to the front end, sub 1 Ohm DCR for the L, with high quality DynamiCaps feeding the driver tube's anode resistor, with less than 1/4 of an inch of lead length between them.
Chassis is Golden Ratio proportioned, made of 14 gauge, with welded corners, powder coated Midnight Blue Wrinkle with a little pearl in it, crummy photos don't capture it. All tubes are Golden Ratio conservatively run, and will last tens of thousands of hours and will consistently perform.
Notice in the third photo, my use of multiple TCSS wiring on cathode cap ground returns, and the use of a SHORT central "star" ground. The amount of paralleled wire for every span was selected by ear.
In the last photo, you will see another first in tube audio, the lead outs of the Magnequest DS-050 output transformers have been modified to multiple TCSS for each span, determined by ear. This provides maximum signal transfer of a linear kind, and a dynamic contrasting capability, that is a WHOLE lot of fun to listen through critically.
Two stages, direct coupled, well wired, with a great supply ..... this amp is easily as good as I have executed in 60 years of me hearing Altec 604s. Proof of the pudding is in the eating.
My Dad, by the way, installed a new 604B in our family's rec room in New Jersey .... when I was only 8 years old.
This is my not-quite finished prototype, if I built another one, it would be neater !
LowOhms
honestly,Quote:
Originally Posted by mah
i use caffeine.
aren't most over 50 now?Quote:
There are hi-end audio reviewers who are no Spring-chickens.
By the gallon.Quote:
Originally Posted by tomt
Well, I was under the impression that less than 1 mV of ripple was the goal of a clean PS, especially with DHTs and low powered SE amps. The amp I posted about has about 100uV ripple on the 2A3 B+ and less than 4uV B+ ripple on the driver tubes.Quote:
Originally Posted by LowOhms
http://www.hostboard.com/forums/hbmc...2013/06/22.jpg
Message for Analog AddictQuote:
Originally Posted by analog addict
The power supply you designed for your 2A3 amp was a PERFECT example we can use.
I have attached (below) your PSUD ... and my original PSUDed supply filters.
You are "under the impression" that low ripple is the goal of a 2A3 amp B+ supply filter. Nothing could be further from the truth, I am sorry to say.
We have tested B+ ripple amounts on Altec speakers, and we have determined that 500 mVAC is absolutely NO problem with SE amplifiers, and even higher, up to 800 mVAC is tolerable ( tested on ALE drivers, very high efficiency ). Push Pull, over a volt of AC B+ ripple is OK.
The SE output transformer steps down the B+ ripple seen by the speaker by the square root of the primary, often 2,500 Ohms, to the square root of the secondary ( often 8 or 16 Ohms ). That is 50 to 4, or a 12.5 ratio reduction of ripple at the speaker terminals.
In the two attachments, I subjected both of our PSUDED supplies ( up to the Finals ) to a 15% current step test. In each case - increasing the load from an idle of 56 mA. to 65 mA.
Look at your filter.
It dropped 11.71 VDC in B+ with a 9 mA. current change. It took about 1,550 ( estimated by eyeball ) mS. to settle. The computed Z of your B+ filter is 11.71 VDC divided by .009 A. or 1,301 Ohms.
Look at my filter.
For the same increase, a 56 mA. to 65 mA. current step, my B+ dropped only 2.60 VDC and it took only 22 mS. to fully settle. The computed Z of my supply filter is 2.60 VDC divided by .009 A., or 288 Ohms.
TWO POINTS HERE:
(1) John Swenson, E.E. and DIYer, has shown us the importance of obtaining 50 mS. or less as a settle time. Your supply took 1,550 mS. or 70.45 times longer to settle, than mine, and missed 50 mS. by "a country mile."
(2) We are taught that it is good to have a source that is 1/10th the load to ideally drive the load.
The plate resistance of a 2A3 is about 750 Ohms as I recall.
So let me ask you a question, what power supply filter will better drive an 750 Ohm 2A3 plate ?? 1,301 Ohms or 288 Ohms ??
Neither are ideal, ( one to ten ) ... we need solid state rectifiers to get that.
Better that I ask, which TUBE RECTIFIED B+ filter will best supply a 2A3's plate, 1,301 Ohms or 288 Ohms???
As you see, my suggested B+ filter to the Finals implementation simulates and is 4.51 times "stiffer" than yours.
If you Analog Addict are at all serious about audio and audio design, simply write to me for the power supply compilation design notes. You (and most others) have never heard a 2A3 do what it can optimally do...I promise you that !!!
The 2A3 DHT tube is a "direct access to the music" (1) device. As such, it demands a great power supply for high performance.
Thank you, Analog Addict, for sharing and posting precisely as you did !! Your example was "perfect" in a positive way to contrast for you - and all others.
Cheers.
LowOhms
(1) Robert W. Fulton, phone conversation, 1982.
Tom T, ..... can I use your High Efficiency system to test-out one of my new amps?? You can be brutal, critical, but mostly honest about what you hear !!! ????????????? Fun to do.
I'm thinking AA meant 2mv or less ripple at the amps output terminals, not on the B+ supply itself.
Ron
Hi Ron,Quote:
Originally Posted by RonSSS
Not at all, as far as I deduce, from AA's writing.
Notice below, AA uses BOTH the terms mV ( as in mVAC ) and also the term uV ( as in uVAC) in his post. Look :
"Well, I was under the impression that less than 1 mV of ripple was the goal of a clean PS, especially with DHTs and low powered SE amps. The amp I posted about has about 100uV ripple on the 2A3 B+ and less than 4uV B+ ripple on the driver tubes."
So Ron, AA has the supply to the Finals filtered as 100 uVAC, which is 0.1mVAC. He has 4/1000ths of 1 mVAC to the driver stage.
A uV is 1/1,000 of a single mVAC , is it not ?!!
In essence, AA has designed exclusively for abnormally low ripple, equating that in his mind with "audio goodness".
Today, some of us know low ripple comes at the horrific expense of other important music parameters that go missing, such as great bass, great dynamics, and PRAT.
AA's amp was not designed to retain the dynamics in music. It will have poor and out-of-time bass and sound like a woolen blanket has been thrown over the Altecs.
Most of you tell me that a SE low powered amp won't play loud and play with good bass and dynamics on Altecs. I say "baloney". Some of us KNOW how to do it today, and the amp (such as AA's) you directly experienced is just mis-designed and mis-made. Music is not steady state test tones, but rather an asymmetrical series of perturbations upon the power supply.
I'm not picking on AA or Zelgall, almost ALL the SE tube amps I hear, DIY and commercial, are mis-designed and I would grow bored listening to them within ten minutes or less.
I always keep in mind, when made properly, the low powered triode amp with no negative feedback loop becomes the holy grail for Altec type speakers !!!
Cheers.
LowOhms
Crap darn, I f'n forgot to post my resume.......
I do appreciate the education on basic electronics though.
Thanks!
Ron
Here is a very recent ( finished last week ) DIY triode amp, made by a long-time Altec 604 user from Saint Louis, Drummerwill :
The LP 845 amp: It took 4 months of planning..... - drummerwill - Tube DIY Asylum
It employs a 9 Ohm DCR power transformer !! and many sub-10 Ohm DCR power supply chokes. I pretty much was involved in all aspects of this design, but it was made with Willie's hands, and he is using it now.
Very "pretty looking" amp, ( somewhat crowded ), but ultimately, for Altecs, I prefer simpler two stage direct coupled designs.
LowOhms
Alien_Shore,Quote:
Originally Posted by Alien_Shore
Attached is the basic direct-coupled two stage amp schematic.... power supply and audio combined.
I absolutely LOVE this circuit topology when well executed. It is as simple as one can make a practical amp !!!
This is the basic Loftin-White circuit from 1929,as used in well regarded amps today such as made by Fi, Moth, and Serious Stereo.
If any Altec speaker enthusiast wants to DIY build an amp, contact me for additional information, I've written it all up. If you don't like to DIY build, spend $15K and order two of the Serious Stereo monoblocks, a bargain. They are easily THE best sounding amps available for Altec speakers ever made, hands down, no contest. A DIY effort need not use a 2A3 as the Finals tube on A-7s, etc.
LowOhms
To my ears, assuming a good schematic and build, a 45 will always sound better than a 2A3 on Altecs. And most importantly, more musical. Of the amps I own, my Loftin-White 2A3 is about 4th on the list.
But it has a buzz...that's not acceptable, is it?Quote:
Originally Posted by LowOhms
Next I plan to improve the 10.0 volt output tube filament supply. Right now they are very quite, but a slight buzz on my 604's...
In my world, Mission 1 is rock solid reliability, mission 2 is dead quiet, both mechanically void of transformer buzz as well as electronically void of any speaker hum.
Without those features, it doesn't matter what the amp sounds like.
Quote:
Originally Posted by alancohen
Q. "But it has a buzz...that's not acceptable, is it?"
A. Of course it is acceptable to have a buzz or humm in a tube amp, every experienced person knows that !
READ as to what Willie went on to say, on his own :
Audio Asylum Thread Printer
Your statement 2 :
"In my world, Mission 1 is rock solid reliability, mission 2 is dead quiet,"
Agree 100% on Mission 1, disagree 100% on Mission 2.
You make the same novice mistake that Analog Addict made ....seeking an amp with low ripple. The good reasons WHY you are wrong ( about an amp being "dead quiet" ) have been shown earlier by me in this thread !
BTW, is your new 300B amp dead quiet ?? :-) Hypocrite.
An amp that is dead quiet is always a dead sounding amp, and always out-of-time in relationship to the music. It misses information and on-time information is lacking...always.
Willies amp is possibly the best sounding 845 SE amp ever made to date. It has a well thought out modern power supply that has not ever been applied this way, to any 845 amp. His supply is superior to all others extant.
Transformer buzzing you mentioned ?? Ha!! I personally designated all the specs to that transformer.
(1) It weighs 18 pounds, wound with 900 mA. capable wire, even though the load is 180 mA. in stereo.
(2) It has a DCR of under 9 Ohms from either end of the high voltage winding to center tap, just the DCR it takes for what I like to call ultra-high fidelity. Measure other power transformers as to DCR !! " Takes 10 Ohms or less - to boogie the best. "
(3) It has multiple TCSS lead outs, applied at the time of manufacture, which is totally unique AFAICT, so it is specifically optimized for SE audio performance.
The power supply is IN the audio circuit in SE, and it all needs to be worthy. Why do you think people say "that SE amps are whimpy, can't boogie" ........because they ARE that way .......when mis-designed.
Willie's, and mine, isn't !
How it sounds, after reliability, is ALL that matters in an amp.... the ability to perform is everything.
LowOhms
But you designed a wonderful transformer...that buzzes. Keep it. He says that he can't hear the buzz at 88dBs. That tells me he can hear it at 87dBs. Nothing would fatigue me more than listening to that.
And BTW, I can read. You don't need to use annoying red lettering and oddly placed bold print for emphasis. It only makes it look like you're trying to establish a point that you can't back up otherwise. Like "an amp that it dead quiet is a dead sounding amp". Hogwash.
And yes, this 300B system is virtually dead quiet. When you first turn them on there is a slight hum. After they start heating up, within about 2-3 seconds, it shuts off and becomes a black hole of non-sound. It's so quiet that I habitually reach for the volume knob thinking it is either very low or off, only to find it is where I left it at about 12 o'clock, which at that level will produce 99dB in my living room.
The amazing thing about that statement is that these are OTL 300Bs. As you know in an OTL the cathode is connected directly to the speaker. In a 300B triode, the filament is the cathode. It took quite a bit of clever engineering to make that work. I know you won't bother, because you know everything, but anyone else who's less endowed can read about how it was accomplished here...Tubes and Circuits by Bruce Rozenblit. It's a great read for tube heads.
As far as I know, this 300B system is a unique 3 box configuration. The PSU is the bottom box. It converts 60 cycle AC to 25 cycle AC before supplying the filaments. That effectively lowers what little hum there might be to beyond the ability of most speaker systems to reproduce it or humans to hear it.
http://www.hostboard.com/forums/hbmc...2013/06/25.jpg
The amps themselves are the epitome of uncluttered simplicity:
http://www.hostboard.com/forums/hbmc...2013/06/26.jpg
http://www.hostboard.com/forums/hbmc...2013/06/18.jpg
And FWIW, they sound anything but dead. My listening area is 21' x 60' and at 12 o'clock on the volume knob they fill the house with glorious sound. Rated at 1.5W into 8 Ohms, I can get 100dB at my listening chair with my 604s. They have thunderous bass and etherial mids & highs...and no buzzing for Pete's sake. The whole package was only $1699 (sans tubes) and 3 days of soldering, not $15,000 and 4 months to build.
I turn them on the minute I wake up, they run all day and I hate turning them off to go to sleep. I'm a very happy camper.
Correction . The transformer I designed does not buzz at all. You got that wrong.
There was posted speculation that it may be a filament or a filament transformer that is the cause.
My power transformer design was for Willie's amp's B+ supply.
Well, I am glad you are happy. What looks on the surface to be good is the frequency conversion for DHT heating. The fact that you run a single tube front end can also be good. It is a far simpler circuit than the cathode follower amps you posted previously.
Listen on and enjoy yourself !!
LowOhms.
Likewise...Quote:
Originally Posted by LowOhms
It is usual design practise to have any resonance in the power supply occur at a frequency well below the lowest frequency of the amplifier's bandwidth.
Lowohms, your posted schematic shows C1=0.47uF, L1=72mH & C2=20uF forming a high Q series resonant circuit with f(res)=131Hz. This is within the audio band width of the amplifier and considering component tolerances and inductance variation under dc loading, resonance may well be excited by the 120Hz ripple in the circuit.
I have no idea what that means, but I'm not talking about resonant frequently. I'm talking about changing the 60Hz AC frequency to 25Hz for AC heated filaments.Quote:
Originally Posted by mah
Quote:
Originally Posted by mah
Correct on your computations. But my circuit is not at all "usual" design practice, which I have found to be inadequate.
The thing you have not thought about is that the small c/L1/C1 combo cited does not power the audio circuit Finals at all, but it is part of a two stage filter to the finals, consisting of small c/L1/C1/L2/C2. L2/C2 is what feeds the Finals.
small c, ( 0.47 uF ) is not always necessary, but L1/C1/L2/C2 most certainly are.
This new filter design has serious advantages and works much better than anything I have heard in over thirty years of designing and building DHT zero-feedback-loop amplifiers. Write to me mah with your email address and I will send you ( or anyone else ) the EE compilations ( John Swenson and John L. Hasquin ) on the design.
I am drlowmu at gee male dot commie.
Best wishes,
LowOhms
A Type 45 is a lovely lovely pristine tube. You are also running less current through it, about half of what a 2A3 will run, so it makes less demands upon the typical power supply to perform.Quote:
Originally Posted by timoteus
Once you make quantum leaps in power supplies, all bets are off on what sounds best. Hell, I have a triode connected $2.00 6AQ5 at home now that will boggie with any Type 45 conventional amp . Lets swap schematics one day. Fun to do.
LowOhms
Jeff, my amps don't boggie. Nor have any of the amps I've ever made. I was in a swamp that was a bit boggie, but not recently.
I feel that your insistence that only your way of making a good amp is not realistic and not open minded at all. You believe that people should take your word for what works best as gospel but you present nothing other than a "my opinion is right and yours is wrong" attitude. You have been proved wrong in other forums where the high tech folks reside and you come here to try to convert the unaware. I'll take a pass on your ideas, not because I haven't tried them but because they're noisy and band width limited. I don't sell or try to sell my friends/associates amps, I've been making my own with my own concepts (right or wrong) for as long as you have and your stuff reaks of BS and dogma.
I've now got a drawer full of Triad trannies and low ohm Hammond power trannies that were expensive but instructional and will use them in traditional supplies and amps as required. The shills that you line up for the I'm right parade can keep the crap you espouse, I'm keeping my excellent sounding amps at all costs.
I think you're over your head in technical discussions as you've admitted and you should stick to expressing opinions rather than facts you can't back up with anything other than a remote subjective thought.
Just my opinion and you're entitled to disagree.