SETs and Horns

[DasguteOhr]

Hello, I'm not sure yet whether a pure tube control is good, maybe a mix of tubes and mosfet. I will first build the circuit on a board and test it. The best result is built into the housing. here the basic circuit without regulation, the values calculated in the head. there are still no final values a hand-painted sketch sorry.
I will continue to report, first of all I have to have transformers wound

Forget something

 

[Atmasphere]

Hello, I'm not sure yet whether a pure tube control is good, maybe a mix of tubes and mosfet. I will first build the circuit on a board and test it. The best result is built into the housing. here the basic circuit without regulation, the values calculated in the head. there are still no final values a hand-painted sketch sorry.
I will continue to report, first of all I have to have transformers wound

You'll want to put a grid stop on that second grid, and some cathode resistors of low value (50 ohms or so), one in series with each cathode, to prevent one from hogging current. Alternatively you could have a seperate cathode resistor for each tube, each with its own bypass cap, which would do the same thing, since the grids and plates are paralleled.

 

[DasguteOhr]

You'll want to put a grid stop on that second grid, and some cathode resistors of low value (50 ohms or so), one in series with each cathode, to prevent one from hogging current. Alternatively you could have a seperate cathode resistor for each tube, each with its own bypass cap, which would do the same thing, since the grids and plates are paralleled.

Yes . each grid with gridstopper as close as possible to the tube. did not draw it. thanks for the tip with the cathode resistors with bypass electrolytic capacitor. a question do you switch a small film capacitor parallel to electrolytic capacitor in your amplifiers, or nonsense?

 

[bonzo75]

With a multi-cell horn, I don't think deeper than 250 to 300hz. This is a Horn made from Dietmar in Germany.
View attachment 76298

The multi cell used in it is an Altec replica made by Markus klug. Yes you are correct about the horn cut off so the cross over is usually around 500, not sure for that speaker

 

[Atmasphere]

Yes . each grid with gridstopper as close as possible to the tube. did not draw it. thanks for the tip with the cathode resistors with bypass electrolytic capacitor. a question do you switch a small film capacitor parallel to electrolytic capacitor in your amplifiers, or nonsense?

You can try it but I think you'll find that as long as the audio that the bypass cap has on it does not exceed about 80% of the total DC voltage on the cap, that it performs as well as a good quality film cap. The film bypass will likely only be effective at ultrasonic frequencies. This is why electrolytic bypass caps have worked so well over the last 90 years or so

 

[microstrip]

Yes . each grid with gridstopper as close as possible to the tube. did not draw it. thanks for the tip with the cathode resistors with bypass electrolytic capacitor. a question do you switch a small film capacitor parallel to electrolytic capacitor in your amplifiers, or nonsense?

Bypassing electrolytic capacitors with film capacitors creates can create high Q resonances - it must be done with care and expertise. Jadis Defy 7 uses cathode biasing with a resisitor in parallel with an electrolytic capacitor - I once managed to ruin the lovely sound of my Defy 7 bypassing these electrolytics with 1 uF film capacitors. BTW, if used without capacitors these resistors would introduce local negative feedback.

 

[petavgeris]

The multi cell used in it is an Altec replica made by Markus klug. Yes you are correct about the horn cut off so the cross over is usually around 500, not sure for that speaker

The Altec horns don't go lower than 500Hz. More specifically, they *should* not go lower. The horns themselves may reach 300 @-3dB but the drivers are not manufactured with the aim to go there. The only driver (besides specific Ale & Goto drivers) that goes down deep to 100 Hz and plays full range is the original WE555.

I have all the replica horns of Markus Klug, 4x2, 5x2 & 5x3. Nothing on earth comes close to them, they are by far the best companion for our compression drivers. I have listened to spherical, conical and tractrix flares, it does not come as a coincidence that all Altec horns were exponential. There exists a reason for this. I still wonder why so many guys out there go and get tractrix/spherical horns and do not get these exquisite exponential horns made by Markus...

 

[jeff1225]

The Altec horns don't go lower than 500Hz. More specifically, they *should* not go lower. The horns themselves may reach 300 @-3dB but the drivers are not manufactured with the aim to go there. The only driver (besides specific Ale & Goto drivers) that goes down deep to 100 Hz and plays full range is the original WE555.

I have all the replica horns of Markus Klug, 4x2, 5x2 & 5x3. Nothing on earth comes close to them, they are by far the best companion for our compression drivers. I have listened to spherical, conical and tractrix flares, it does not come as a coincidence that all Altec horns were exponential. There exists a reason for this. I still wonder why so many guys out there go and get tractrix/spherical horns and do not get these exquisite exponential horns made by Markus...

Have you posted a picture of your horn system?

 

[bonzo75]

The Altec horns don't go lower than 500Hz. More specifically, they *should* not go lower. The horns themselves may reach 300 @-3dB but the drivers are not manufactured with the aim to go there. The only driver (besides specific Ale & Goto drivers) that goes down deep to 100 Hz and plays full range is the original WE555.

I have all the replica horns of Markus Klug, 4x2, 5x2 & 5x3. Nothing on earth comes close to them, they are by far the best companion for our compression drivers. I have listened to spherical, conical and tractrix flares, it does not come as a coincidence that all Altec horns were exponential. There exists a reason for this. I still wonder why so many guys out there go and get tractrix/spherical horns and do not get these exquisite exponential horns made by Markus...

I visited Markus over a year ago, great guy

 

[Addicted to hifi]

A match made in heaven for sets and horns .

 

[cal3713]

I'm curious why avantegarde shows their speakers with non-SET amps given the general the sensitivity level. Is it just because they prefer the reliability of transistors or do they really prefer the presentation?

 

[petavgeris]

I'm curious why avantegarde shows their speakers with non-SET amps given the general the sensitivity level. Is it just because they prefer the reliability of transistors or do they really prefer the presentation?

There exist no more reliable devices than tubes. They are more reliable than transistors. Just operate them with circuitry that is properly designed and adapted to their specs and and you'll never face any issue. I have been stressing power tubes to their absolute limits and I can hardly notice even the normal failure in transconductance. In a power amp with 211 tubes that I have manufactured 9 years ago, the measured emission and transconductance of United CUE-211 and 311 tubes was found to be the same as it was when the tube was new. And it has well more than 10k hours on its back...
If you know how to design power amps the proper way, tube life and reliability will never be an issue. Never.

 

[cal3713]

There exist no more reliable devices than tubes. They are more reliable than transistors. Just operate them with circuitry that is properly designed and adapted to their specs and and you'll never face any issue. I have been stressing power tubes to their absolute limits and I can hardly notice even the normal failure in transconductance. In a power amp with 211 tubes that I have manufactured 9 years ago, the measured emission and transconductance of United CUE-211 and 311 tubes was found to be the same as it was when the tube was new. And it has well more than 10k hours on its back...
If you know how to design power amps the proper way, tube life and reliability will never be an issue. Never.

So do you think AG chooses SS because they prefer the sound then? Or is there another reason?

 

[petavgeris]

So do you think AG chooses SS because they prefer the sound then? Or is there another reason?

Hello!
I really have no idea. To my thoughts, all this is related to marketing policies and attempts to downgrade the amplifier portion for good sound requirements and focus on loudspeakers by emphasizing electronics built in house. AG speakers are hybrids, semi-passive and semi-active, you cannot play them with the amp of your choice. There is always a very strong compromise and you'll never experience the sound *YOU* like. Period. End of story. You must rely on manufacturer's choices and design considerations, good or bad. So this is in my opinion the real motive behind the AG concept. 'We give you the very best, mount the amp of your choice and all the rest is trouble-free'... Everybody knows that tubes play better than SS on these speakers... 'Common secret'...
Manufacturing good loudspeakers and more specifically good drivers, is an extremely costly process. You can't built a commercial speaker with exceptional drivers because the costs are prohibitive. There is nothing bad for this, please don't blame me for talking sometimes counter- or anti- commercial words. Everybody has (and must have) his share in the world and do research to offer the vest best, and of course make a living from it. But on the other hand, there exists *NO WAY* to achieve crazy sound quality with ordinary, cheap or commercial drivers. FYI, my biggest full Field Coil project, 3-way speaker, with mercury vapor tubes for power supplies throughout, high voltage field coils, my exotic hand wound transformers and of course all the metal work required, has already cost me more than 38.000 Euros, personal work for coil winding, studying, calculations, measurements, electromagnetic field simulations, all counting already thousands of hours, all being excluded. The project is still alive, after aprox. four years of effort...
I'm writing all this so as to get an idea that some things are not necessarily as they appear to be. At AG they have their reasons for preferring SS, as this helps them being more efficient in producing the best they can and make the most out of their product.

 

[Lampie519]

Next time try a Zotl SET. You will be surprised how clean a SET can be.
It is alway funny to read impressions of a certain topology and it is (almost) never true as there are good and bad examples of all topologies... (even there are good pentode amps, PP amps, OTL, etc.) It all depends on how well it is executed. Just because "we" have not heard any it does not mean they do not excist.

 

[Rensselaer]

So ever so slightly less than double the power. But at that power level, that's still significant. I think there are other similar tubes, like the 6A4, which is a pentode with its suppressor grid tied to the center of the filament as it is directly heated.

Have you ever considered using something like a 6BL7 or 6BX7? They would make about the same power, and you could use just one for stereo if you are uncomfortable with the idea of paralleled sections. They have a really nice family of curves looking very similar to that of the 45. It has the advantage of being indirectly heated, which can help with circuit design in a number of ways. I know this might be considered blasphemy by some but the linearity of the tube is more important than where its directly or indirectly heated. The reason DHTs are so revered is that many of them have very good linearity.

I you're playing around with tubes like this, I have a box of prewar audio tubes that would love a good home.

Atmasphere,

Does the 6BL7 (or 6BX7) run the left channel through one side of the valve and the right channel through the other side of the valve when used singularity for stereo amplification? If so, why doesn't one signal in that valve effect the other, as electro-magnetic energy on one side of a transformer effects (and brings about) similar (but different value) flow of electro-magnetic energy on the other side of a transformer? I am reminded of how amplifier builders braid their wires (when bundled) to prevent effects, and how we as enthusiasts cross leads at right angles in the same belief. All BS?

 

[Rensselaer]

One more guy that confirms what I've been telling for more than 10 years. At least, it seems that there are quite a few here in this forum that prefer to write the truth, instead of hiding around, having the preoccupied idea that they will be accused of blaming manufacturers, challenging egos, etc. This is not our intention of course. There comes the time that truth should shine. There exists no preoccupation, inflated ego or selfishness here, just a few open & true words that reflect more than a decade of experience. You can still go and purchase Avant Gardes, Acapellas, Magicos, Wilsons, Focals, whatever you like, but it would be good to know from the very beginning that this is another world that is not at all related to things mentioned in earlier posts. I have listened to many systems around, equipped with loudspeakers like the above ones but I would personally never think of going to purchase any of the ones mentioned above, for the reasons expressed in my previous comment.

It is not a coincidence of course that all the experienced guys that I have met, sooner or later, migrate to Altec/JBL/Klangfilm/Western Electric DIY loudspeakers. It is not a matter of 'if' but only a matter of 'when'. You can't go wrong with any of the above ones, although they possess slightly different virtues and have some drawbacks that IMHO are minimal. What they do is opening a window with unique transparency and faithfulness to the source. The Tesla speakers that were mentioned above are really top performers and of course it's not a coincidence that they sell for big bucks.

Yes, if you can, go this way, as it really makes a difference!

And of course time alignment is really crucial. On your FL horns, pay attention to the TS parameters of the drivers, as not all of them are designed to perform their best under any conditions. Others are designed for OB, others for closed boxes and others for vented boxes. If you need some assistance, do not hesitate to ask.

Say, on my Altec A7's I wanted to slide my Altec 802-8B drivers (mounted to 511B horns) back so that they are vertically aligned with the 416-8B low frequency drivers inside the 825B (A7) cabinets. Wouldn't the sound of the 511B horn be directed down into (and reflected upward from) the top of the 825B bass cabinets? Wouldn't that cause more problems than alignment would correct? Please advise.

 

[Atmasphere]

Atmasphere,

Does the 6BL7 (or 6BX7) run the left channel through one side of the valve and the right channel through the other side of the valve when used singularity for stereo amplification? If so, why doesn't one signal in that valve effect the other, as electro-magnetic energy on one side of a transformer effects (and brings about) similar (but different value) flow of electro-magnetic energy on the other side of a transformer? I am reminded of how amplifier builders braid their wires (when bundled) to prevent effects, and how we as enthusiasts cross leads at right angles in the same belief. All BS?

There probably is a little crosstalk, but in terms of electro-magnetic issues its no worries at all. The layout of the circuit would have greater effect!

 

[K3RMIT]

There exist no more reliable devices than tubes. They are more reliable than transistors. Just operate them with circuitry that is properly designed and adapted to their specs and and you'll never face any issue. I have been stressing power tubes to their absolute limits and I can hardly notice even the normal failure in transconductance. In a power amp with 211 tubes that I have manufactured 9 years ago, the measured emission and transconductance of United CUE-211 and 311 tubes was found to be the same as it was when the tube was new. And it has well more than 10k hours on its back...
If you know how to design power amps the proper way, tube life and reliability will never be an issue. Never.

Forget measurements for now , have you tried new tubes same tubes and let burn in for min 50 hours.
Then with your ears tell us how much better the new tubes sound hahahah. reg reliable I can’t see how a tube is more reliable then a SS device
what parameters did you use to make your claim

 

[K3RMIT]

Using bypass caps is a hit and miss. i use high voltage Polly caps but as stated above things can get derailed
reg tubes on horns I just can’t see why most stay stuck on tubes. but an set amp designed well even a push pull one has some great qualities
just look at VAC all or most all of there stuff makes many ss amps or even other tube amps sound less in sound