Beyond the Ariel

[PierreQuiRoule]

So the next step is ordering the parts: AH425 horn and Radian 745NeoBe driver. But what Slagle autoformer ? intact audio

I'm bi-amping the system, so aside form the passive HF EQ you and Pierre worked out, will I need any other kind of filter?

In case you are interested, I am using a Werner (mast_mutter) autotransformer. The one with 1.5 dB taps.

Pierre

 

[Lynn Olson]

Lynn,

Just a suggestion - if the chassis is steel (particularly on the light side), the problem might not be the transformers. I recently had an issue in an amp I made where it turned out to be the chassis box buzzing in response to the transformer's magnetic field. Some spacers and rubber pads did the trick.

A few years back I got rid of an amp because I could hear acoustic hum and buzz. Now I wonder if I could have just spaced the transformer a little further from the steel chassis on that one, too.

Unfortunately it's the transformers (and the chokes, too). The top plate is aluminum (not steel) the side cheeks are wood, and the bottom is open. So there's no chassis magnetic induction.

If anyone has recommendations for quiet power transformers and chokes, I'd like to know. It would be nice if they were electrostatically screened as well ... that gets rid of a lot of line noise.

I very much appreciate Zigzagflux's experience with the RC-coupled 6SN7 input stage. A tube as linear as a 6SN7 (and there are so many to choose from!) isn't going to be working very hard to deliver 12~15V rms into each 45/46 grid. It's also nice that 46's are plentiful and a good alternative to 45's.

The weird thing about the Karna amplifier is that it is so damn transparent; every little stupid change in the system is audible. It still sounds like a 300B amplifier, just much more powerful than SET's, except for the gonzo transmitter-tube SETs with 1500V power supplies.

 

[zigzagflux]

It's hard to argue with an input stage that looks like this with 20V output to the driver grids. Just think what a 45 could do with this. Overall result is around 26W at 4 ohms.

Output at 1W is a barely noticeable 2nd at -135 dB (-93 effective). That's a world better than what I was getting with the first stage IT, consisting of a lot of 3rd and 5th.

Look forward to seeing how the Coleman Regulators work on the 46 and 300B; that was another motivator to rebuild the amp from the ground up. Along with the bifilar Monolith IT; able to get a few dB less distortion over the Lundahl.

Not to digress from the speaker discussion, but you are intending on using the amp to drive the new speakers.

 

[g3dahl]

Gary said something earlier that I am not sure you clued into. He said he can not hear the high frequencies anymore. I often hear this and question those statements. What I mean by that is what is more typical is that your hearing acuity is just diminished and slopes down from a certain frequency and not that you truly can't hear these frequencies at all, that would be some more serious hearing loss.

I don't think my hearing's HF limitation is at all unusual for my age (54). The statistics I found online regarding the normal range of HF loss with age were pretty shocking, to be honest; I feel that I've gotten off pretty easy. My comment wasn't based on testing by an audiologist, but rather from my observations when testing tweeters. Sweeping a sine wave into a tweeter and watching the measured output on the screen, the sound that I hear drops off rapidly as I reach 15 kHz, but the screen shows the output hasn't gone away.

I wonder how many readers of this thread would find themselves in about the same place if they carried out the same experiment.

Musically, the distance between 15,000 and 20,000 Hz is just three steps of the scale--a fourth, or five semitones, and this in a range in which we don't perceive pitch anyway. I don't feel like I'm missing a whole lot. But it does impact my priorities when working to optimize my system.

Gary Dahl

 

[Lynn Olson]

Man! The 2nd harmonic is at 80 dB down, the 3rd is 90 dB down, and there's nothing else! Astonishing! All with zero feedback.

Tell me more about the Coleman regulators and Monolith interstage transformer; I'm always interested in better performance.

Back when I was twiddling around with the Monarchy sinewave power source, I discovered that adjusting the filament voltage on the 300B's had a fairly dramatic effect on the tonality ... much more than minor things like cable swaps. 5V could sound a bit sharp and tonally washed out, 4V tonally good but also dull, slow, and heavy, and 4.5V had really intense and vivid tonality with good clarity and speed. So if I go with DC on the filament, I'll definitely want to have it both adjustable and repeatable (with a front-panel voltage indicator of some sort). Old-school round meters always look good.

I want to sincerely thank you for forging ahead and trying out a new variation of the Karna amplifier, just as I appreciate Gary Dahl, PierreQuiRoule and Vgeorge building their versions of the Beyond loudspeaker. I look forward to combining the Karna Mk II with the new speaker ... 20~30 watts with an efficiency of 97~100 dB/meter should definitely do the trick.

 

[soongsc]

For the benefit of anyone dropping in on this conversation, Lynn doesn't take issue with the use of transistor amplification in the bass. In his current system, the Karna amplifiers power the Ariels, and a REL subwoofer does its thing below. The upper half of the frequency spectrum is extraordinarily spacious and pure. It plays quite loud before running out of headroom, but the limit is there and Lynn is certainly aware of it. To my ears, the Ariels lose their luster from about 250 Hz downward. The frequency balance is uneven in this range, and sound is less distinct.

The whole purpose of this thread has been to move "beyond the Ariel," with the goal of moving past the Ariel's limitations without giving up any of its strengths. Improving bass performance and dynamic range hasn't been all that difficult, but doing so without sacrifices elsewhere is quite another matter. All of the choices involve tradeoffs, and we all have somewhat different preferences.

Lynn has experience with SE tube amps but doesn't use them in his own system. His Karna amplifiers have plenty of power for the Ariels, but the goal of increased headroom through higher loudspeaker efficiency is a high priority for him.

Gary Dahl

Below 250Hz? I would look into a few areas rather than design a whole new system?

1. Driver performance. I have found the new Wavelet capability in SoundEasy provides good information. The sad thing is that we are still limited to room reflections. Understanding the BL and Km curves are also important. Currently work here is being done to reduce the nonlinear effects of those in the amp end. From what I have hear from earlier implementation is basically the impression of increased dynamics, especially the piano where you have a complication of harmonics and transients.

2. Amplifier damping control. I have a Hafler XL280, but the bass just never seemed to be quite right. While I visited the MyRef amplifier project thread, the damping measurement method drew my interest, and and after measuring the Hafler in a similar manner, it did reveal low frequency damping problems. I am not sure where the issue was with the built or the design.

3. Music polarity. I always flip the polarity when it sounds flat and messy. Better systems will show the importance of polarity.

4. Interface. I always like to make sure the speaker load impedance is as flat as I can reasonably get it. I suspect it will be less of an issue with tube amplifiers, but have not verified. Normally I would call out interconnects, but below 250Hz, it should not be an issue, and I really would need to listen to see if it might be an issue. Generally the effects of interconnects come from impedance mismatch starting from 1KHz and up.

 

[AllenB]

Tell me more about the Coleman regulators

Three goals that I see Rod has set for this combination CCS/gyrator, DC is one, to eliminate IM with the filament current. Isolation of the supply encapsulates the other two, firstly the noise and the hash produced by rectification. Then there is the isolation of the non-grounded end of the filament so that all filament current flows through the filament and not around it.

the sound that I hear drops off rapidly as I reach 15 kHz, but the screen shows the output hasn't gone away.

I wonder how many readers of this thread would find themselves in about the same place if they carried out the same experiment.

Thereabouts

 

[Mooly]

OT posts deleted. The thread is not breaking any rules and its also a fact that any thread with 10k + posts will stray and return to the topic countless times.

 

[marco_gea]

Oltos,
Just as Lynn has his personal preferences, and they are preferences for a specific type of sound, I could not live with most tube amps on the bass speaker. The fact that he keeps bringing up the class A section of the amp tell much of this story. I would bet you money that his amp does get out of that class A region much more than he wants to admit. On any type of music where you have any kind of real dynamic swing and a strong bass note your going to require much more than 20 watts of class-A power. you are going to be into the class-B range for sure. I listen to rock and Jazz and even at a lower level of sound those bass notes from a kick drum or strong bass guitar are going to tax a lower powered tube amp to no end. Yes there are some real tube amps that can put out 150-200 watts but they are more the outlier than common today. Some of the old McIntosh power amps could do this but lean over and pay some ridiculous amounts of money for those. You really are getting into preferences for a certain harmonic distortion here, that is more than obvious at this point. Now when you start making that kind of power with a tube amp you have a mighty nice heater sitting in the room. There are some real low distortion SS amps that don't have the higher order harmonics, you just have to know what you are looking for. typically not many of the atrociously designed audiophile amps that I see out there. I've heard some real nice sweet SS amps and some that sound like a transistor radio. Build the speakers and then try some amplifiers before you make your choice. I do understand your desire to keep your hearing but if you aren't going to put a limiter or compressor on your system you are going to get peaks over 100db with a great recording. A piano is going to do that on lots of Jazz music, so will a trumpet and a great percussionist will do that many times. That doesn't mean you are listening at that level on an average but the peaks will be there and if the amp can't do that it is going to clip and kill the sound. I know a recording engineer who wears foam ear plugs whenever he is out in public, he protects those ears all the time, that is how he makes his living. At the same time he has to be able to listen to full dynamics to record or mix down a track and you do need to have that capability for playback if you aren't going to listen at really low levels. I could handle a SS amp on the bottom and a tube amp on top, but not on both unless like I say it was the rare tube amp that had some real output. Your never going to get away with that with a SE amp and a few watts even with a high efficiency cone driver, it isn't going to happen. I have no idea of how much power that Lynn's tube amps are capable of, but even for orchestral music the peaks can take some real power.

Agreed 100% on this, all the way.
Marco

 

[Kindhornman]

Marco,
I think there is just a preference by some for the sweet sound of second harmonic distortion from tube amps that many like and equate with a pleasant sound. I think the older you are the more you are likely to have grown up with that type of sound. It doesn't make it any better than a great SS amp that if done correctly can have very low 3rd and higher order harmonics. Most people just aren't going to have the room or the desire anymore for large speakers and that means lower efficiency smaller speaker systems. That is when the SS amps are going to win out more than can be expected from a tube amplification stage. A high efficiency speaker system today is so very rare.

 

[thoglette]

Tell me more about the Coleman regulators

Rod Coleman is a regular poster here & much about his regulators is in New DHT Heater thread.

 

[DIYBras]

Someone mention big speakers? Someone mention horn bass speakers?
See below an correct example for an true exponential horn for bass, from an friend of mine:


...I never heard bass sooooooo clear and clean, PERIOD.
Brazilian Backstage magazine plus people from Selenium made an technical review from those "little thing" and they were quite impressed with the result! Far lower THD and HUGE SPL than every another option. Almost 109dB/1W/1m to less than 20Hz.
Unfortunately, I only heard bass demos because the system is disassembled for reform ...
SURE this will be my project beyond the beyond the Ariel (ahem ... TQWT, in my case), when I have a terrain with room for such a venture.
Is there a tip, if someone from DIYA have a good space on your garden... and made every 10k$+ subwoofer seems like an kid toy without dynamics or clean sound.
As for the mid and treble units, I'm watching topics like this one, in order to select alternatives that marry this future projects (My "beyond the Ariel" will be to training and selecting for that).

 

[soongsc]

Man, this is hard core stuff.

 

[DIYBras]

It's hard to argue with an input stage that looks like this with 20V output to the driver grids. Just think what a 45 could do with this. Overall result is around 26W at 4 ohms.

Output at 1W is a barely noticeable 2nd at -135 dB (-93 effective). That's a world better than what I was getting with the first stage IT, consisting of a lot of 3rd and 5th.

Look forward to seeing how the Coleman Regulators work on the 46 and 300B; that was another motivator to rebuild the amp from the ground up. Along with the bifilar Monolith IT; able to get a few dB less distortion over the Lundahl.

Not to digress from the speaker discussion, but you are intending on using the amp to drive the new speakers.

Excellent result! I have always believed in 6SN7 family / 6FQ7, work excellently with RC circuits or current source (see Morgan Jones book about low THD valves); these tubes are indicated for this function.
I myself have similar results in my testings, but with the 6FQ7, which can replace the 5687 without having to change the case/socket, only rewiring the pins (good news for Linn Olson). And I have an little amp for Stax phones who have an balanced stage with E88CC Siemens RC coupled to an 5687 trafo coupled to Stax. I have some complains about some high order residual HD, and this originates from 5687 according my measurements, not from E88CC... The E88CC receives signal RC filtered directly from ESS9018K2M balanced voltage-mode out. Simple as that.

By the way, I love the latest discussions in this topic!

 

[DIYBras]

LP ripping...

You cannot convert LP into digital without losing something. It is like taking Lance Armstrong and reducing him to a good club rider
.

This is my experience, too!

 

[jpak]

It's hard to argue with an input stage that looks like this with 20V output to the driver grids. Just think what a 45 could do with this. Overall result is around 26W at 4 ohms.

Output at 1W is a barely noticeable 2nd at -135 dB (-93 effective). That's a world better than what I was getting with the first stage IT, consisting of a lot of 3rd and 5th.

Look forward to seeing how the Coleman Regulators work on the 46 and 300B; that was another motivator to rebuild the amp from the ground up. Along with the bifilar Monolith IT; able to get a few dB less distortion over the Lundahl.

Not to digress from the speaker discussion, but you are intending on using the amp to drive the new speakers.

I have to echo what Lynn says, those measurements are incredible. Are you using the Pimm pentode CCS or a solid state one? And what is the operating point of the 300B?

Mooly- is the amp discussion the off topic posts that were deleted? Apologies if they are, maybe a new thread discussing them is in order?

 

[g3dahl]

The deletions were not audio-related.

 

[Lynn Olson]

Rod Coleman is a regular poster here & much about his regulators is in New DHT Heater thread.

Looks like they'll do just fine for powering the PP 45's and PP 300B's. The high dynamic impedance is very desirable; the audio flowing through the filament/cathode return circuits sees what looks like a brick wall compared to the very low impedances of the filament/cathode circuit.

The very first version of the Amity amplifier had generic 3-pin regulators for the 300B's, and the effect on the sound was disastrous, sounding like a chintzy transistor radio. As it happened, the regulator failed, and I improvised a pair of dropping resistors so I could AC-heat the filaments.

That sounded much better ... like an entirely new amplifier. So I engaged on a long search for good-sounding regulators, and eventually gave up. That's why I'm so glad to see the Coleman regulators have solved the problem for me!

 

[musical noise]

Looks like they'll do just fine for powering the PP 45's and PP 300B's. The high dynamic impedance is very desirable; the audio flowing through the filament/cathode return circuits sees what looks like a brick wall compared to the very low impedances of the filament/cathode circuit.

The very first version of the Amity amplifier had generic 3-pin regulators for the 300B's, and the effect on the sound was disastrous, sounding like a chintzy transistor radio. As it happened, the regulator failed, and I improvised a pair of dropping resistors so I could AC-heat the filaments.

That sounded much better ... like an entirely new amplifier. So I engaged on a long search for good-sounding regulators, and eventually gave up. That's why I'm so glad to see the Coleman regulators have solved the problem for me!

It seems that the Coleman boards have many followers. This guy here is a serious tube DIY'er and here's what he thinks of the Coleman regulator:

http://www.diyaudio.com/forums/tubes-valves/38248-new-dht-heater-43.html#post2905388

 

[thoglette]

Looks like they'll do just fine for powering the PP 45's and PP 300B's. The high dynamic impedance is very desirable; the audio flowing through the filament/cathode return circuits sees what looks like a brick wall compared to the very low impedances of the filament/cathode circuit.

I thought you'd like that aspect.

They do use a fair bit of power - blew my budget for my current (stalled) build.