Does anyone care to ask an amplifier designer a technical question? My door is open.


I closed the cable and fuse thread because the trolls were making a mess of things. I hope they dont find me here.

I design Tube and Solid State power amps and preamps for Music Reference. I have a degree in Electrical Engineering, have trained my ears keenly to hear frequency response differences, distortion and pretty good at guessing SPL. Ive spent 40 years doing that as a tech, store owner, and designer.
.
Perhaps someone would like to ask a question about how one designs a successfull amplifier? What determines damping factor and what damping factor does besides damping the woofer. There is an entirely different, I feel better way to look at damping and call it Regulation , which is 1/damping.

I like to tell true stories of my experience with others in this industry.

I have started a school which you can visit at http://berkeleyhifischool.com/ There you can see some of my presentations.

On YouTube go to the Music Reference channel to see how to design and build your own tube linestage. The series has over 200,000 views. You have to hit the video tab to see all.

I am not here to advertise for MR. Soon I will be making and posting more videos on YouTube. I don’t make any money off the videos, I just want to share knowledge and I hope others will share knowledge. Asking a good question is actually a display of your knowledge because you know enough to formulate a decent question.

Starting in January I plan to make these videos and post them on the HiFi school site and hosted on a new YouTube channel belonging to the school.


ramtubes

Showing 8 responses by unreceivedogma

Why would triode sound better than pentode?

Why woukd my Altec Lansing 604Cs be better for my Julius Futterman OTL3s At 16 ohms rather than 8 ohms?

And, with regard to the great interconnect debate: do you know of any testing done that approaches that of scientific blind testing that shows that any given wire, if made out of a certain material, and wound in a certain way, and shielded in a certain way, will cause electrons to move in one manner as opposed to another that can be explained as doing so and that because of that movement can be explained as yielding sonic performance that is measurably and quantifiably superior, or even just different?
Hi ramtubes,

thank you for that and here’s a followup.

If triodes are low impedance and OTLs like high impedance, what was Jon doing then when he switched the OTLs to triode?

i can tell you that the amps sound better after the conversion, and they are more stable too. The bias and the balance don’t drift anymore.

Jon Specter made the conversion with some guidance from George Kaye of Moscode. Both formerly worked at NY Audiolabs.
Hi Ramtubes,

”Are we talking about NYAL Futterman? Perhaps I have missed something in this thread? Do you mean Jon Snyder?”

You will be sorry you asked!

Let me fill you in on my setup.

When I was 14 years old (that’s many many years ago. It was the Summer of Love), I started out with a Dyna 70, a Dyna PAS, a Garrard table, a Stanton cartridge, and a pair of Lafayette two way speakers.

Around the late 80s, I had built up to the configuration that I more or less have today:
Altec Lansing 604Cs and 604Ds
Mastering Lab crossovers
New York Audio Lab (NYAL) OTL3s (Futterman)
Beard P505 preamp
Sumiko MMT arm
VPI HW table (MK II then, MK IV with SAM today)
Koetsu cartridge (Black then, Onyx today)

and just this month, I added a Velodyne 15 inch sub that keeps anything below 70 or 75 hz from reaching the Altecs.

The speakers have have been re-coned three times, most recently three years ago, each time by Gabriel Sound in NJ. They do a lot of pro stuff: stadium work for Pink Floyd for example.

Jon Specter, not Snyder, is his name. I found him accidentally when I was following an Ebay listing for a pair of Futtermans. After many weeks with not a nibble, I “contacted the seller” - Jon - and suggested he add search words like Macintosh, Conrad Johnson, etc because “outside of a small circle of friends” as the late great Phil Ochs said, nobody knows what a Futterman is.

Not yet knowing who the seller was, I asked him how he came upon them, and he says he built them himself when he was at NYAL.

How serindipitous. Recently, a tube in one of my Futtermans blew up - literally, glass shattered - and seemed to have taken out half the circuitry. Until then, George Kaye had done my repairs, and while he does excellent work, he lives up in Brattleboro and it’s a schlep (he has his own company, btw, Moscode) and it turned out that Jon lives in Staten Island! So I asked him if he could repair the amp. He said yes but suggested that I listen to his pair - which had the triode mod - and if I liked them to just swap.

So we tried that, and they sounded great, but cosmetically they were a different iteration which I didn’t like so I declined the swap and had him do the mod on my pair and relied on my Dynas while I waited. He relisted his pair per my suggestion and sure enough he found a buyer - in Austin Texas, I believe - in three days.

John did another mod for an old Cooper Union alumni colleague of mine last year: he says that to date, those are the only three OTL3 Futtermans that he is aware of with the triode modification. I know George was involved because I was at Jon’s shop a couple times when he called George to consult on some issues, and I was still keeping in touch with George myself.

The triode mods actually have more power somehow. I know Jon put a tiny little transformer in there somewhere, he explained what it is for and that it’s not in the output circuitry but I’m not technical enough to remember.

I think you said that you dont believe in “audio grade caps” but Jon put a bunch of them in the Futtermans, the Beard, and the Mastering Labs. Jon said they would take about 100 hrs to break in and I didn’t hear anything at 100 hrs. At 150 I still didn’t hear it and I was beginning to wonder if I wasted some money, but at 200 they kicked in and I did in fact hear a difference, nothing dramatic, it was subtle: the sound became silkier and more open.

Btw, Jon also plays a great blues guitar in a band that he has, and is a cousin of Al Kooper.

The result of this configuration of components and the work put into them is a very, very lifelike presentation. I have heard equipment - some of it quite expensive, eg speakers that cost three times as much as my entire system - in audio showrooms that sound more accurate in terms of the timbre/texture of voices, instruments, etc. And you must know that for decades audiophiles would sneer at Altecs. I’m sure there are many in this forum. But I am telling you, I have never heard anything that comes even remotely close to having the lifelike acoustical space, nor the absolutely incredible dynamic punch that this configuration does. With some recordings - I’m thinking of the Frank Sinatras in particular, both Capitol and Reprise era, even the mono presses - the effect is of a startlingly present and holographic sound. The one weakness had been the bass was sometimes wimpy. With my new listening room and the Velodyne, that problem is gone.

As for Pearson: I sometimes read reviews in Stereo Review of components costing $30K to ... what is that pair of horn speakers (funny how horns are back!) for $600K? Magico? I would regularly post the comment “Is the Law of Diminishing returns somehow made obsolete in the audio world? Where is Haffler now that we really need him?”

One anecdote with regard to expensive speakers and irresponsible audio designers/manufacturers and then then I will look forward to your reply:

I was walking home one day, when I was still in NoHo in NYC, and I saw a pair of speakers through a storefront window in an audio showroom that caught my attention. I went in for a closer look.

The cabinet was about the same same size and proportions as mine were. The speakers had no grille cloth, so I could see the coaxial driver, identical to mine. The only thing different was the cosmetics of the cabinetry, which had a beautiful brick colored wood finish. I looked at the price tag, and then asked for a salesperson. I asked him what went into the $33,000 cost of the speakers.

After about 10 minutes he more or less concludes, and I say “that’s all interesting. Now could you tell me if that is a 604C or a 604D driver in there, or did the manufacturer copy it from scratch?” He looks a little confused. I continue “I know that’s an Altec 604C. I’ve been using them for almost 40 years. In your presentation, however, you did not once mention that fact. What distinguishes this speaker from the 604?” He then goes back to the crossover design, and I interrupt “I heard you the first time. It sounds like the Mastering Lab crossovers, by Sachs. You did not mention him. Everyone knows that the stock crossover in the Altec wasn’t what it should be, and Sachs came up with a two shelf design. I see similar knobs on the back of the cabinet.”

I continue “So, it seems like, excepting for the craftsmanship of the cabinet, which is extraordinary beautiful, these are the exact same speakers as mine - drivers, crossovers, cabinet geometry. Except that I put $3,300 into acquiring mine and getting them to perform at their best, while you are asking for ten times that amount. Are you suggesting that the cabinet aesthetic is worth the $29,700 difference? Or is there some other magic that this manufacturer has put into the performance - which is where the rubber is supposed to meet the road - of this pair of speakers? Could we remove the back panel, maybe, and see inside, see what has been put into this?”

By this time, I had attracted a small crowd. I concluded by saying “Sorry, I have an appointment to make and I’m already late, maybe another day! Thank you for your time!” I left, figuring that some dumb Wall Street sucker who doesn’t know what to do with his money will pick them up. They did, in fact, sell within the month.
PS:

the speakers could have have been changed to 8 ohms at re-coning. I kept them at 16. They are rated 101 dB efficiency.

The Futtermans are now about 45 Watts each. .
analogluvr,

I’ve been curious about the Atmospheres.

I have a 3 disc LP set of Theodorakis’s “Canto General” that Atmosphere produced, and I found the engineering to be disappointing. It has been muddy, and there has been no bass to speak of. I have yet to listen to it in the new environment with the sub. Maybe it will sound better.

As for setup, I run the signal through the preamp, then into the Velodyne servo, which splits the signal and sends above 70 to the Futtermans and below 70 to a 300 watt ss amp within the servo and then to the sub, which is also connected to the servo by another line that as I believe they say in their literature “digitally corrects for phasing” in order to reduce distortion from that source.

By cutting off the signal to the Altecs below 70, it gives them much less work to do and they sound clearer.

When I go to shows, the way I would put it is that I almost never hear anything that I would prefer, and never ever hear anything that I would prefer that’s within 300% of what I have spent on my system.

Nice to meet you. It’s nice to know that there is somebody out there who thinks and hears similarly. By hearing, I mean that my ears, from an early age, grew accustomed - maybe trained is the word - to hearing audio a certain way. My system no doubt sounds very colored to many, but it suits me fine.
Ramtubes,

My bad. I rarely go to shows. I meant showrooms. Audio store showrooms I presume are set up to show the gear at some approximation of optimability.

By “more power” I’m just going by where I set the volume control before and after. It was a surprise, as I thought there would be less, and I was pleased because in my layman’s view it meant less stress on the tubes and circuitry.

There wasn’t much more volume, as the goal was simplicity, as you say; stability, as I have observed; and even more transparency in the mids, as I have also observed, though the Jensen caps also had something to do with the transparency eventually.

So, if you are building OTL triodes too, Jon is not correct. There are more than three. But are you using the same design approach? You guys should talk to each other!

Also, I’m not sure what you mean by better technology than cone speakers. First off, the Altec is a horn/cone hybrid. That aside, while electrostatics have their virtues, they don’t move air the way a cone does, as someone here also observed. That’s what I mean by the dynamic punch of the Altecs. I’ve heard some great horn speakers, with prices in the stratosphere. 

The serial number on my Altec dates them as 1954, the year I was born, lol. If it ain’t broke...
Ramtubes:  

“SPL”

you just went technical on me. 

I’m gonna take a wild guess: sound pressure level?

I think the debate between cone and electrostatic is reminding me of the great cable interconnect debate. Could it be that this is just personal preference? Or even that my ears are just trained and accustomed to whatever cones do to the ears? I’ve listened to my share of electrostatics. Some were very impressive. Some were better than my Altecs in many respects. But none moved me. 

Back to SPL. I do get the bit about moving air as opposed to mass. In theory, that is more efficient.  But then if true, there would be an electrostatic subwoofer. ? Maybe there is? 
Atmaspheres:

I have 6,000 LPs. A lot of them have a good bottom, some have an excellent bottom. 

I love the Theodorakis performance, but alas it’s like listening through cotton.

Let’s see what it sounds like in my new room. I’ll let you know. 

M