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10-19-2016

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	76
Post ID:	22822
Reply to:	22821

1R vs 16R

With near 1R impedance I presume you will have multiple bass drivers paralleled. That is perfectly legitimate way to operate but there are a few things you might consider.

The mistakes at 1R are more effective then at high impedance. If you have 16R then you get some difference of sound if you change from 16R to 12R. You will have the same sonic difference if you change from 1R to 0.9R. The operation point at low impedance point is a bit too sensitive. Driving 1R you will have more sonic difference when you change from 250mA to 300mA on 6C33C’s plate then it would be driving 16R. The symmetrical clipping become a bit more aggressive with low plate loading. I do not know why but I did observed it. At 16R the voltage and current clippings were more gently introduced then with 2R loading. The speaker cable behave a bit differently then what I was accustomed. The cable are running in “current mode”, so the “best” cable for 16R load would not be not the best for 1R.

Still, if everything is done properly then there is no difference what loading impedance would be 1R or 16R. The 1R has some advantages as the DCR of the transformer is lower and the bass drivers matching become a bit less critical…

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

12-07-2016

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anthony
Posts 338
Joined on 08-18-2014

Post #:	77
Post ID:	22873
Reply to:	22822

I've started building the power supplies...

I designed up a steel chassis for both the Fullrange and DSET Melquiades. Here they are screwed together for the first time.

Four Ned Kellys.jpg

Then I have made sure all the cutting and drilling has been in the correct places by quickly putting the parts in their places. The Fullrange Melquiades will has a separate power supply just in case I take things further and make it three channel. There is plenty of room to add more iron in there. First the bottom shelf...

Mockup Fullrange Front.jpg

The DSET power supply is much more hefty with no spare room. The bottom shelf...

Mockup DSET Bottom 1.jpg

...and the middle shelf...

Mockup DSET Mid 1.jpg

Power supplies are down the bottom, diodes in the middle and chokes are on the top shelf.

The cases are made from steel but the aluminium platforms are used to keep the magnetics at least 20mm from any ferrous material. I have used sorbothane bushings to isolate the individual platforms from the steel chassis in an effort to minimise vibrations. All iron (apart from the toroid for the services supply) are custom wound by a very smart fellow in Melbourne (Lucas Cant from Black Art Audio) and are built on large cores for tight regulation (generally 1% or 2% regulation), low heat gain (no more than 20 degrees) and low impedance.

Everything has been painted or powder-coated since these photos were taken and I am currently building all four supplies in my evenings and whatever spare moments I can grab.

12-08-2016

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	78
Post ID:	22874
Reply to:	22873

Steel singing

Anthony, have you tried powering this all up (with dummy loads) to see if the outer steel skin will not sing? 20mm is nothing for LF magnetic induction.

Best luck,
N-set

Cheers,
Jarek
STACORE

12-08-2016

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anthony
Posts 338
Joined on 08-18-2014

Post #:	79
Post ID:	22877
Reply to:	22874

Not yet

Hi N-Set, I am three quarters of the way through assembling the first power supply to power-up stage so I have not tested the "singing" as yet. It is something that I have thought a lot about. First and foremost I wanted a steel skin around the power supply for EMF/RFI suppression as well as trying to mitigate the flow of stray flux into the room from the power supply itself...there is a lot of iron in those boxes. So I went with relatively thick 4mm steel panels partially for mass (to appropriately load the industrial footers I have ordered), partially for ease of working (I prefer to work with something that is difficult to bend or dent) but mostly to have adequate steel thickness to shield the room from the magnetics.

The 20mm gap was something that I talked to my transformer winder about and that number was decided as a reasonable distance where there would still be some magnetic coupling but its strength would be somewhat reduced. I could use larger distances for lower coupling but then the power supply case gets enormous and they are big enough already. Internally, I have a minimum separation between individual pieces of iron of 50mm, usually a little more. So with the knowledge that I will have coupling I introduced a couple of measures to mitigate it: the aluminium platforms sitting on sorbothane bushings; a constrained layer damping for the steel panels.

From my calculations, the properly loaded sorbothane bushings should be capable of decent isolation for mains frequency vibrations and harmonics. I have not tested it yet of course, but if the iron couples strongly enough to the steel panels the sorbothane should be effective at allowing the iron to move a little whilst isolating that movement from the chassis itself. Whether this works in part or in full is yet to be seen, but that is my hope.

Secondly, on the inside of the 4mm steel panels I plan to apply a vicoelastic polymer and 1mm thick aluminium sheet to act as constrained layer damping so that any ringing is snuffled before it becomes a problem. This material is specially designed to damp ringing steel panels in industrial applications and has some decent measurements to back it up so hopefully I can apply it effectively.

Cheers,

Anthony

PS: My hope is that the power supplies feel "soft" to move around...a product of the anti-vibration measures I have used.

12-09-2016

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	80
Post ID:	22878
Reply to:	22877

Copper?

Ok, quite impressive measures, I also once had an idea of sandwitched cabinet construction. Hope it will work. 4mm steel is quite rigid but weights a lot. If $$$ permits you may consider copper for the inner layer instead of alu to create a good electrostatic shield as well.

Best,
N-set

Cheers,
Jarek
STACORE

01-16-2017

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anthony
Posts 338
Joined on 08-18-2014

Post #:	81
Post ID:	22926
Reply to:	22878

Ringing

Now that I have tried it the CLD works wonderfully, at least to the knuckle test. There is absolutely no ring to be heard and it now sounds like rapping your knuckles on a very heavy solid wood door, but probably lower in frequency. Dull and soft are two words I would use to describe the sound.

01-16-2017

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anthony
Posts 338
Joined on 08-18-2014

Post #:	82
Post ID:	22927
Reply to:	22926

Anthony DSET Power Supply Schematic

To keep with Romy's spirit of sharing his work, I have attached a file of VER 1.0 of the DSET Power Supply. There are quite a few differences to Romy's published schematics but it is basically the same beast. You will notice a lot of power transformers in each supply, 10 in all including 4 separate filament transformers, the services toroid and five EI's for Bias, DHT, drivers and power stages. The relays got a bit complicated after I ordered the wrong coil voltage for the time delay relays and then had to go with it.

The biggest difference to Romy's schematic is that I have added a dedicated DHT power supply. This is a double choke LCLCR with 8,000uF final filtering cap.

Power transformer ratings have been re-worked to suit the new supply arrangement and chokes are all sized and properly gapped for those currents.

http://www.goodsoundclub.com/PDF/DSET%20Power%20Supply%20Schematic%20V1.PDF

02-02-2017

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anthony
Posts 338
Joined on 08-18-2014

Post #:	83
Post ID:	22943
Reply to:	22927

First Fullrange Melquiades power supply is done...

It looks good to me. As you can see I have left plenty of room to add a couple of more channels.

Going together.jpg

The bottom level contains the power transformers and relays. The diode bridges hang from the the middle shelf and the chokes and filters are on the top shelf. I've included a foot-pedal for on/off duties. The DC cable will connect at the top of the case, the AC cable from the front, and the captive power lead and foot-pedal to the rear of the case.

Going together 4.jpg

Here is the closed up case. It sits on industrial neoprene footers that at this weight rating give it isolation from about 20Hz or so, which is low enough to decouple any vibrations from the floor. Tap the PS with your toe and it wobbles about like jelly for a few seconds.

Hanging Around.jpg

The second power supply is now under construction as are the DSET power supplies, the bottom shelf of which you can see below...

DSET started.jpg

02-02-2017

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anthony
Posts 338
Joined on 08-18-2014

Post #:	84
Post ID:	22944
Reply to:	22943

Bread-boarded Melquiades Fullrange

Romy,

Using the Fullrange PS I have bread-boarded the Fullrange amplifier...

Lights On.jpg

Turn off the lights and it looks much better.

Lights Off.jpg

To my surprise (this is my very first amplifier build) everything seemed to work pretty much straight away. The voltages seemed right, nothing blew when I applied power to the Bias string, which was my main concern and once I was sure things seemed relatively stable and well warmed up I plugged in my daughters CD player and played the Frozen Soundtrack. Nice!

I do have some concerns with the Bias string though, with regards to it seeming to drift, or not stay at 0VDC offset. I could not find anywhere on the site where you describe the process of tuning the Bias. I measured the current across R11 and R12 in the range of 8mA - 9mA, which does not seem to be enough, so I paralleled another pair of 5kOhm resistors to halve their resistance and ended up with 15mA-16mA. But the Bias will still not stay at 0VDC. Romy, are you able to describe the process to tune the Bias String? Please treat me like a novice this is my first build and my background is farming, not electronics.

Regards,

Anthony

02-03-2017

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	85
Post ID:	22945
Reply to:	22944

It look like the project progress well

It look like the project progress well. I have a little concern about heat the will be building up in your PS enclosure. I do not know what kind ventilation hole you have in there but be advised that it will be quite hot. In worst case you might put a little 4-6” fan in there…

Regarding your bias problem. This is normal and it is very easy to deal with. Short the amplifier input jack. You should have about minus 3.4V at the driver tube grid or about 200V on plate. That would be depends the quality of your tube and if you have 185-215V on plate then it is still OK. Your bias is set by negative (green) supply chain and resistor R6. The positive supply chain (red) is just compensates the same voltage that negative cleat on the left side of the resistor R5. This is bias resistor and keep it exactly as it is (unless you build filters at input). The values that are given in the schematic are very accurate but they presume that you use gas tubes that give 150V. In reality they never do. Some of them stabilize voltage at 148, or 149, or 151 volts. They are not bad tube, this is how they works normally. So, you might have a positive gas tube give 151.6 and negative gives 148V and then you do not have enough voltage on positive side to set zero at input. Pay attention in negative side we have R10 = 10K and on positive side we have R9 which is hale of it and then trimmer run +/- 10K. So, of you a few KOhm not enough then just change the value of R9. Alternately you can do what I usually do: switch the tubes, positive and negative between each other, or get another gas tube. Between 2-3 tubes I always find a configuration where I can get zero at my input. Sine you find a right set of tube and adjust to zero input it should reminds like this for years. If you use a direct coupled preamp that accidently runs DC at output then you can even to correct if at your power amp input.

Another aspect that you need to recognize is that 8mA at amp input is VERY little and it should not affect sound at all. All that it will do “bad” will be creating auditable click when you connect and disconnect cables. As you understand when your cables are connected then your positive supple (red) is grounded to your preamp output impedance. My preamp has 8R output impedance, so when my cables are connected I might even to pull the positive tube out or turn off positive supply – it will have very little impact to anything. Well, if I disconnect the cable after this then I have voltage burst that might burn my driver tube and might send the speakers diaphragm flying. This is what we have positive supply and balance the input to zero, because we want the amp to be balanced independent from the environment and to be stable.

Rgs, Romy the Cat

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

02-05-2017

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anthony
Posts 338
Joined on 08-18-2014

Post #:	86
Post ID:	22949
Reply to:	22945

Ventilation

Romy the Cat wrote:

It look like the project progress well. I have a little concern about heat the will be building up in your PS enclosure. I do not know what kind ventilation hole you have in there but be advised that it will be quite hot. In worst case you might put a little 4-6” fan in there…

Yes, the ventilation is sort of "wait and see" at this stage, but it is based on convection. In the photos above you can see some stainless steel mesh that I have glued over the exterior ventilation holes...there is some on the bottom shelf and some on the front and back panels. The industrial footers that I have chosen for the PS sit it quite high, about 30mm+, above the floor which means that the bottom ventilation has plenty of room to draw in air from the floor. The ventilation channels are virtually full length of the case and are aligned like a chimney with the same slots cut in the sides of the middle shelf to let the warm air rise more or less without impedance. When it reaches the roof of the PS chassis it will push out of the ventilation slots on the front and back panels. The system seems to work. I let the smoke out of a resistor during power-on testing and it dribbled out the convection slots just as I had imagined it would, so hopefully I will not have to install any fans (but there is allowance for fans at a later date).

The iron in the power supplies has also been designed and wound for low temperature rise (on big cores)...I think the biggest temperature rise is expected to be 14C-16C above ambient. When the transformer winder long-term tested his mathematics outside the confinement of a case he managed a 9C temperature rise on the biggest piece of iron, so my fingers are crossed that I can keep temperatures manageable without a fan.

Romy the Cat wrote:

Regarding your bias problem. This is normal and it is very easy to deal with. Short the amplifier input jack. You should have about minus 3.4V at the driver tube grid or about 200V on plate. That would be depends the quality of your tube and if you have 185-215V on plate then it is still OK. Your bias is set by negative (green) supply chain and resistor R6. The positive supply chain (red) is just compensates the same voltage that negative cleat on the left side of the resistor R5. This is bias resistor and keep it exactly as it is (unless you build filters at input). The values that are given in the schematic are very accurate but they presume that you use gas tubes that give 150V. In reality they never do. Some of them stabilize voltage at 148, or 149, or 151 volts. They are not bad tube, this is how they works normally. So, you might have a positive gas tube give 151.6 and negative gives 148V and then you do not have enough voltage on positive side to set zero at input. Pay attention in negative side we have R10 = 10K and on positive side we have R9 which is hale of it and then trimmer run +/- 10K. So, of you a few KOhm not enough then just change the value of R9. Alternately you can do what I usually do: switch the tubes, positive and negative between each other, or get another gas tube. Between 2-3 tubes I always find a configuration where I can get zero at my input. Sine you find a right set of tube and adjust to zero input it should reminds like this for years. If you use a direct coupled preamp that accidently runs DC at output then you can even to correct if at your power amp input.

Another aspect that you need to recognize is that 8mA at amp input is VERY little and it should not affect sound at all. All that it will do “bad” will be creating auditable click when you connect and disconnect cables. As you understand when your cables are connected then your positive supple (red) is grounded to your preamp output impedance. My preamp has 8R output impedance, so when my cables are connected I might even to pull the positive tube out or turn off positive supply – it will have very little impact to anything. Well, if I disconnect the cable after this then I have voltage burst that might burn my driver tube and might send the speakers diaphragm flying. This is what we have positive supply and balance the input to zero, because we want the amp to be balanced independent from the environment and to be stable.

Rgs, Romy the Cat

Thank-you for this information Romy. Hopefully I will get a chance to test this in the coming week. I should state that I had no problem getting to 0VDC at input, rather it would not stay at 0VDC...for example after a few minutes it might have wandered up to 60mVDC or down to -20mVDC.

02-06-2017

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	87
Post ID:	22954
Reply to:	22949

Fear of forced ventilation.

anthony wrote:
…. so my fingers are crossed that I can keep temperatures manageable without a fan.

I do not think you need to be afraid of forced ventilation. There is a feeling in Hi-Fi that forced ventilation is some kind of derivative from pro audio equipment but I do not think that there is anything wrong with it, Particular on PS side. The fans are getting better and better each year and today you can 8” fans that run a full power under 26dB noise. You do not need them to run at full power but rather 300-600 rotations per minutes that is enough to create a very fine air flow taking heat out of box. They are silent and practically vibration free if to issue them properly.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

02-14-2017

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anthony
Posts 338
Joined on 08-18-2014

Post #:	88
Post ID:	22973
Reply to:	22954

Dust

It is not a fear of forced ventilation per se, rather a fear of dust permeating the enclosure. You may have noticed that the power supply chassis' have been designed without ventilation holes on the 'roof'...this is to eliminate dust-fall into the interior. When it gets dry and hot here it also can get quite dusty...computers with forced ventilation require frequent cleaning but I don't want to be pulling the sides off my power supplies regularly to clean them out so I have attempted convective cooling...we will see how that goes.

I don't think that I can get away from forced ventilation for the amplifiers though and will have to grin an bear the consequences in this climate.

02-14-2017

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	89
Post ID:	22974
Reply to:	22973

A filter?

It is very easy to deal with. There are intake fan covers with foam filter and they work VERY good. I have something like this running in my amp and it is very clean inside after many years.

https://www.amazon.com/MASSCOOL-Plastic-Cooling-Filter-FFT-2P-120MM/dp/B00366YKQU

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

02-25-2017

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anthony
Posts 338
Joined on 08-18-2014

Post #:	90
Post ID:	23035
Reply to:	22974

DHT Meter

Romy, do you have a panel meter on the DHT channel? I am currently designing the chassis for my DSET and looking at your schematic there is no panel meter for either driver or DHT. Just trying to figure out what would be useful to have in my amp.

Regards,

Anthony

02-26-2017

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	91
Post ID:	23037
Reply to:	23035

Current matters?

Sorry, Anthony, I do not follow what you are asking. What does it mean “panel meter on the DHT channel”? My DHT channel has a plate current matter. I find it useful but not truly necessary. My sited at 38mA for years and does not move. Hypothetically is should move lower than the cathode of DHT will lose emission… I just find is very convenient to have one single glance at the amp and to see all plate currents. Some people might advocate that a plate meter worsen sound, I valid argument but I voted against it. I di don’t know that you factor in your amp a DHT channel. I think it is a good move. You might experiment to drive your DHT with DHT driver. It would be kind of violation of my main multimapping premise: to have all amp of the same topology but a properly cooked full DHT might be incredible interesting. In fact the most interesting amp I even hears in my life was 3 DHT stages….

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

02-26-2017

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anthony
Posts 338
Joined on 08-18-2014

Post #:	92
Post ID:	23038
Reply to:	23037

Yes, that is it.

Romy the Cat wrote:
Sorry, Anthony, I do not follow what you are asking. What does it mean “panel meter on the DHT channel”? My DHT channel has a plate current matter. I find it useful but not truly necessary. My sited at 38mA for years and does not move. Hypothetically is should move lower than the cathode of DHT will lose emission… I just find is very convenient to have one single glance at the amp and to see all plate currents. Some people might advocate that a plate meter worsen sound, I valid argument but I voted against it.

That is what I meant, an ammeter for the DHT plate current. I don't see that the plate current is adjustable anywhere in the circuit, and you don't show the meter in the circuit diagram so I wondered if you actually used one. In my situation it will be difficult to fit a sixth meter as the amplifier chassis is currently laid out so I am tempted to leave it out.

Romy the Cat wrote:
I di don’t know that you factor in your amp a DHT channel. I think it is a good move. You might experiment to drive your DHT with DHT driver. It would be kind of violation of my main multimapping premise: to have all amp of the same topology but a properly cooked full DHT might be incredible interesting. In fact the most interesting amp I even hears in my life was 3 DHT stages….

Yes, I have five pairs of YO186 that I wish to try out as well as some 45's in particular. The amplifier will be designed so that I have relatively easy access to the parts that I am likely to alter once I get it operational and I start fitting the amps into my playback. Perhaps I will play with DHT drivers...the 841 looks interesting...but first I have to get everything built and tuned and then look at what, if anything, I wish to change.

This 3 stage DHT that you have heard is recent news? Most interesting. More details?

02-27-2017

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	93
Post ID:	23040
Reply to:	23038

Do not rash

anthony wrote:
That is what I meant, an ammeter for the DHT plate current. I don't see that the plate current is adjustable anywhere in the circuit, and you don't show the meter in the circuit diagram so I wondered if you actually used one. In my situation it will be difficult to fit a sixth meter as the amplifier chassis is currently laid out so I am tempted to leave it out.

Note there is no adjustment for DHT plate current. It is direct coupled and it set but power supplies voltages and driver gain. So, there is no truly need for a meter in there, still you do want to know how much current you drive over the tube. So, make two externally accessible contact point with a pair of test jacks, something like this:

http://www.newark.com/tenma/spc15338/test-jack-combination-insulated/dp/79K4930

Put between them a good quality 1R, relatively powerful resistor of higher accuracy and measure the voltage drop over the resistor. This way you will be using voltmeter instead of ampermeter and the plate voltage will not flow over ampermeter. You can even decouple the voltmeter with a pair of very large resistor (like mOhms) to make sure that plate current do not “see” the bad voltmeter and then to recalibrate what voltmeter you would use. I actually did experiment with it and I find that there is no difference to sound and 1R voltage dropper works very fine.

anthony wrote:
Yes, I have five pairs of YO186 that I wish to try out as well as some 45's in particular. The amplifier will be designed so that I have relatively easy access to the parts that I am likely to alter once I get it operational and I start fitting the amps into my playback. Perhaps I will play with DHT drivers...the 841 looks interesting...but first I have to get everything built and tuned and then look at what, if anything, I wish to change.

Hm, you managed the get YO186? That is very cool. She sound very much along with RE604 but has lower support and more “meety”. Be advise that relatedly low operation point that it set in my DHT makes her to sound a bit “distorted” and very underpowered, which is perfect for my overly clean MF channels. If you are willing to play with other DHT driver then do NOT implement my MF channel and keep your option open. You do Milq DSET for the rest of the channels you will be able to drive your MF from Milq DSET. Then, after some listening IF you feel that you need to change anything you will be able to add a discreet DSET of your choice.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

03-04-2017

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anthony
Posts 338
Joined on 08-18-2014

Post #:	94
Post ID:	23047
Reply to:	23040

12.1k Resistor

Hi Romy,

Minor question with hopefully a simple answer.

In the DSET schematic you have a 12.1k resistor in the bias for channels B, C, D and F. I have some nice 12k resistors here (not 12.1k) that I could use in those positions...can you see a problem with this? A couple of years back I got a bulk lot of Vishay VTA55 60R resistors which are the axial leaded equivalent of S102. I plan to use these as grid stoppers (will use 60R not 50R as in the schematic) and I will also use them to tie grid to plate in the 6E5P/6E6P tubes.

Can you see any problems?

I can't wait to build these amps. The chassis' are in the final stages of design so hopefully I can have some steel cut and powder-coated in the next few weeks.

Regards,

Anthony

PS - I have been listening to the prototyped fullrange Melq through a single speaker for a few weeks. The speaker is not appropriate for the amplifier but there is still this "uprightness" to how it handles dynamic changes that it so wonderful. Yesterday I switched back to a solid state amp in stereo and I got volume and bass control but it is sterile in comparison...that dynamic change is almost monotonic and quite boring by comparison. I'm looking forward to getting the Melq onto some horns!

03-04-2017

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	95
Post ID:	23048
Reply to:	23047

You are looking for 200V on plate.

I do not see why substitute between 12.1k and 12.0k would be a problem. This will slightly change the driver bias and plate voltage as the result but the natural discrepancy of parameters in the tube is very high and you shall be still within the margins. You want to have 200V on tube plate. Using different new tubes you will see that with the same fix bias they can give you from 185V to 215V and it is still OK.

anthony wrote:
…The speaker is not appropriate for the amplifier ….“

Do not do it. The worse you can do is to drive with Milq some kind of 88dB sensitive monitor. You will not accomplish any good sound and most likely will destroy the monitor’s twitter.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

04-05-2017

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anthony
Posts 338
Joined on 08-18-2014

Post #:	96
Post ID:	23098
Reply to:	23048

DSET amplifier is designed

It took a LOT of time in CAD using what I had learnt from building the power supplies and then adapting it to match the requirements of the rest of the system. I have decided to mount the DSET on the horn stack and direct connect the speaker cables. This makes the design quite difficult in that have to work around the pillar, provide adequate horizontal and vertical vibration isolation and still meet the component layout requirements for a sound assembly.

Did I say I spent a lot of time in CAD sorting all this out...I did...months...in the end much, much more time that I thought was reasonable for the task. There were several iterations along the way and talking to different people and receiving the intended parts to be included in the chassis meant alterations to the design were prudent. For example, in my second or third to last design iteration I finally weighed all of the components and estimated the steel weight and realised that the amplifier was going to be a two man lift and that if I wanted to tweak anything in there I did not want to be pulling it off the horn stack, carrying it downstairs, working on it, carrying it back upstairs and reinstalling it...I needed access to all the most likely tweak areas while it was still sitting on the horn stack so I could put down a dropsheet and bring the soldering iron up to the amplifier. Afterall, if tweaking something is that much of a logistical exercise you can guess how much fine-tuning will be done...none!

I like simple designs for complex things and in some way I think that I have achieved that, but in other ways I certainly have not. I wanted a clean top with only valves showing, I wanted it mounted on the horn stack, I wanted all the cable connections pointing vertically rather than horizontally and I wanted all the dials, knobs and meters located either front or back but not at the sides. The build will be complex with multiple levels of components not to mention the sheer weight involved, and I think that I have a good logical layout with enough room for various components. When the 'package' gets too heavy during assembly I will just install it on the horn stack and the bring up various pre-assembled portions for final connection in-situ.

Step one of the build will be the floor with associated cooling fans (filtered!) and vibration isolation.
Build Step 1.jpg

Next will be the filter caps, output transformers and bleeder and service circuits:
Build Step 2a.jpg

The OPT's will sit on small sorbothane isolated vibration platforms. The internals are mostly aluminium so the OPT's will not couple to them. The floor and all external panels with exception of the top panel are steel.

Then the meters and knobs will be bracketed and the beginnings of the PLLXO's installed.
Build Step 3a.jpg

The two white boxes at the top of the image below are filter chokes for the PLLXO's. In the end I have opted (at the winders insistence) for them to be potted in heavy steel shielding rather than mumetal, which makes the overall product much larger, but also less expensive and more robust. The HF filter is both magnetic and EM shielded by steel and an aluminium EM box.
Build Step 3b.jpg

Sometime during this stage I anticipate that the amplifier will be mounted on the horn stack. Some final assembly and it should all look similar to this:
Work in place.jpg

Notice in the image above that the tubes sit by themselves on a 'rafter' that can be exposed by removing the top panel. Remove the back panel also and I have reasonable access to the PLLXO and other important areas that I am likely to fine-tune. All of the pots on that back panel are actually installed on brackets inside the amplifier and I can just remove some knobs, undo some screws and the amp is still perfectly operational with the panel removed.

Looking from behind at a closed up DSET, you can see that the BNC connector to accept the interconnect is vertical rather than horizontal. I did this because of the height at which the amplifier will sit and the stress that this will place on some cables. I have also added a battery powered digital multimeter and switch so that I can check the DC Offset from time to time. This way I don't have to connect up a multimeter to check when I am curious or whenever I change regulator tubes. When I am finished I just flick the switch that removes the battery power and there are no deleterious affects to SQ (my dac has this same arrangement to check DC offset). I had considered using the same battery powered digital voltmeters to check plate currents but in the end opted for the more aesthetically pleasing analogue meter.

DSET from behind.jpg

On the image of the top plate below you may be able to make out the air venting around the base of all of the tubes. The two case fans in the floor of the chassis push air up through the case and the major exit point is around the valve bases. Hopefully the rest of the chassis is sealed up tight enough that enough air exits vertically from the top plate to keep everything cool inside. It is for this reason that I have included two 80mm fans in the design just in case I need more oomph...I can opt to run either one or two depending on how the situation is when it all is assembled.

DSET top.jpg

And finally an image of the system concept at this point in time:

Sound System almost designed.jpg

Guys, if you have any constructive criticism or tips please chime in.

04-05-2017

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noviygera

Chicago, IL
Posts 177
Joined on 06-12-2009

Post #:	97
Post ID:	23099
Reply to:	23098

Prototype

Do you have the speakers as pictured already in place, or at least in the form your beautiful rendering shows? I would recommend to try a mock up of this layout in your room and not proceed with the full custom build. For example, I don't think the array of low efficiency woofers would have the continuation of the "horn sound" and I think a single high eff large woofer or a few 15's, in line (above) would be a less "forced" transition. That's just my experience and I would surely try a draft version first, especially with side flanking midbass like that.Gera

04-05-2017

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anthony
Posts 338
Joined on 08-18-2014

Post #:	98
Post ID:	23100
Reply to:	23099

Not built yet

No, I've not built the big woofer towers yet, but have some steel here to make the first few Cannons up to try out and measure and listen to to see if I can make the system work. It is essentially the same solution that Romy uses so I think I should be able to get a decent result but I will only know once I have tried.

I have left the door open to add a mid-bass channel using a Vitavox 15" woofer and place it on top of the horn stack if required. Again, we will see if that is required. If it is then the woofer towers would lose an octave or so of range and be limited to sub 40-50Hz (at the moment I anticipate they will be used sub about 80Hz)

04-05-2017

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	99
Post ID:	23101
Reply to:	23098

Built in vibrosiolation

Very cool idea with a built in pneumatical (?) vibroisolation!
I run a small company offering pneumatic isolation platforms for audio. I attempted to
talk to various equipment manufacturers about building in such solutions into their products.
Unfortunately no interest in that. But great to see someone taking this idea seriously.

Cheers,
Jarek

Cheers,
Jarek
STACORE

04-05-2017

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oxric
Posts 194
Joined on 02-12-2010

Post #:	100
Post ID:	23102
Reply to:	23100

Impressive project

Hi Anthony,

I am amazed by the work you have accomplished so far and love your stands and horns stacks.

Two comments though in term of overall esthetics although I realise that having spent so much time on this it may be too late to make changes.

I would not have the amplifier hidden behind the main pillar supporting the horns. It distracts from the beautiful lines of horns and support. In addition, I think, if only in theory, to completely isolate your amplifiers and power supplies from your horns and drivers, would be a good thing. I appreciate that you do reduce cable lengths by doing so but am inclined to think that by positioning your amplifiers along side walls, the benefits outweigh these other disadvantages.

Secondly, the bass cannons. Sadurni Acoustics does something very similar but I think this contraption with the several separate individual bass enclosures is an unecessary distraction from the horns and support. I would try to use a bass tower, maybe two modules of 4 drivers each, and still make provision for alignment of these drivers within its design.

Please ignore comments at leisure as your project is quite remarkable as it is.

rgds
Rakesh

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