Author Topic: New custom monoblock tube amps....  (Read 21624 times)

Offline Response Audio

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Re: New custom monoblock tube amps....
« Reply #30 on: November 21, 2011, 01:05:53 PM »
Interesting amplifiers Shane. Any pics of the units up and running? Any measurements you wish to share?
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Offline hometheaterdoc

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Re: New custom monoblock tube amps....
« Reply #31 on: November 21, 2011, 03:33:20 PM »
photos are in the gallery thanks to Steve from Rich's get together:

http://www.audionervosa.com/MGalleryItem.php?id=1010
http://www.audionervosa.com/MGalleryItem.php?id=1009

I was going to take a shot of the innards when I had them open last night... never got around to it... too anxious to listen...  kind of crazy to see the 5 power supplies lined up.... 

if we were to ever commercialize it, it would need a custom wound power transformer... that would likely take care of some of the heat that has to be thrown away because some of the off the shelf power transformers aren't quite what is needed.

Also, cutting down on the trannies would allow you to use a much smaller chassis arrangement...  it would also need to be done differently to allow better airflow... there's a reason that BAT uses the perforated chassis design... and their amps aren't run nearly to this level...  right now in this current wood setup with very minimal ventilation, it's not ideal....  getting the chassis up on cones definitely helped and allows it to pull the cool air up from all the holes in the bottom through convection...  still needs more ventilation on the top though to allow heat to escape through the top...

the amps take a long time to make in the current configruration since everything is hand soldered including all the little boards...  getting stuff done up in CAD so it could be done on boards and flowed out through a contract manufacturer would likely reduce construction time considerably...  but that would be something to look at if Sol wanted to take this commercial and do a run of the amps...  I will say that this eats every other 6C33C based amp I've had here for lunch...  not even close... and that's with no break-in time... hopefully they improve and go up a few notches with a couple part tweaks...
« Last Edit: November 21, 2011, 03:42:47 PM by hometheaterdoc »
Shane Sangster
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Offline hometheaterdoc

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Re: New custom monoblock tube amps....
« Reply #32 on: November 24, 2011, 07:57:28 AM »
I think Sol said that they dissipate about 500W. They are class A up to 10W, plus the heaters, transformers and regulators.

According to my newly installed last night PS Audio P10 power conditioner/regenerator, they are pulling ~690W out of the wall.... definitely not green amplifiers :)  it didn't quite dim the street lights outside, but I haven't seen this kind of power draw since some of the early plasma displays...  they make nice foot warmers :)

they're doing their best to use up all the available capacity of the P10 power regenerator...  they're a good tool to help break it in though :)  we'll see if this is the first power conditioner I can leave amps plugged into... all others have failed in their previous attempts (the RSA Dmitri was the closest to being an unconditional winner... but a couple amps didn't like it as much as straight into the wall.. it was ridiculously good though on most pieces)...

By comparison, the PS Audio PWT on repeat playing a disk to break-in the AMR DP-777 tube DAC is only pulling 89W off the line... with the PS Audio PWD sitting there turned on but just idling since it isn't hooked up to anything...

got to play a lot more classical on them twice this week with folks over for dinner.... can't wait to get rid of the mechanical buzz from those caps that need to be swapped... the soundstage is going to take a bit to get used to... I'm not sure I want to put these on the Harbeth Monitor 40.1s, which are a huge soundstage speaker to begin with... adding this kind of presentation might be too much of a good thing....
Shane Sangster
Used to be Night & Day Audio.......

Offline tmazz

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Re: New custom monoblock tube amps....
« Reply #33 on: November 24, 2011, 09:16:29 AM »

According to my newly installed last night PS Audio P10 power conditioner/regenerator, they are pulling ~690W out of the wall.... definitely not green amplifiers :) 


Tell me about it. My VT-200 draws better than 600W at idle:roll:
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Offline richidoo

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Re: New custom monoblock tube amps....
« Reply #34 on: January 26, 2012, 02:49:19 PM »
3 issues remain, vibration noise and heat from power tranny, noise from power tubes, and cooling.

Yesterday I cut up the pretty boxes I made last year to allow more ventilation. It does seem to help. I remember the amps being much hotter last time I used them when they were first born.   But they are still too hot to touch the top plate. Some  of the heat is radiating onto the top plate from the power tubes. Other heat is coming from the power transformers which are conducting heat to the top plate by their metal to metal mounting.

Hopefully rubber mounting the transformers or something like that will reduce heat and vibration transfer to the plate. Any suggestions on how to isolate the transformers? They are hanging upside down, and there is about 1/2" of room before they hit the floor.

Wooden bracing will be added to the plate to prevent sagging under the weight of the transformers and damp the vibes too. Screen will be added to the box holes.

Offline Carlman

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Re: New custom monoblock tube amps....
« Reply #35 on: January 26, 2012, 06:06:47 PM »
Could you put the transformers in their own boxes? 
I really enjoy listening to music.

Offline topround

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Re: New custom monoblock tube amps....
« Reply #36 on: January 26, 2012, 06:27:28 PM »
You mean like potting them?
System consists of an amp a preamp, 2 speakers a turntable and a phono preamp, Also some cables and power cords and a really cheap cd player.

Offline richidoo

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Re: New custom monoblock tube amps....
« Reply #37 on: January 27, 2012, 07:51:38 AM »
Separate PS boxes would move the problems away from the amp box, but they would still need to be solved in the new box. It would be nice to keep it all in one chassis for convenience, and it should be solvable. This is just prototype crap to be expected. Next one will be shaped like a chimney with concrete basement for bolting down the power tranny.  :drool:

Here are the pics Shane asked me for. Bottom pic is focused on the inside floor.




It is a treat having them in the house again, because they sound so good! This vibration fix might take a while...

The innards are pretty complicated compared to typical "dumb" tube amps, so I can't imagine doing this as a DIY, but it will have to be, because Sol ain't building anymore big tube amps.

Offline hometheaterdoc

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Re: New custom monoblock tube amps....
« Reply #38 on: January 27, 2012, 08:43:10 AM »
The Catch .22 problems....

1) Since this was a prototype amp, I wanted to make sure I was fully on board with the design and any tweaks and modifications before even thinking of spending $500 each for one off custom CNC'ed metal chassis.  Thus the wood box with single piece of plate on top.  However, with only one piece of metal plate to act as heatsink and heat dissipation (with wood all around it insulating and trapping the heat), it really needs something else sooner rather than later to prevent so much heat being inside the chassis.

2) I really like the look of having a flat top and only the tubes themselves on display, with the trannies and everything else hidden underneath... but that just means more heat trapped inside the un-ventilated metal plate and wood chassis.  Punching too many more holes in the top plate would allow more heat to escape vertically, but affects the aesthetics and look.  Going to ventilated chassis plate like you see on something like the BAT amps would be ideal, but that means dis-assembly and re-assembly of prototype on another top plate...  putting the trannies on top like a traditional amp would help with heat issues inside the chassis, but then you don't have the same kind of look....

3) This amp has fully regulated power supplies for *everything*...  So to get a fair bit of regulation on all these supplies, you have to throw away the extra voltage as heat when it isn't being called upon...  more heat trapped inside the chassis...  or lots of heat being coupled to the metal plate to help dissipate it...  it's not like this build is like the AMR amplifiers... they use their whole chassis (and it's all very thick aluminum and huge, heavy, and super thick copper bottoms and backs) as the heatsink... not unlike how the Butler Monads used to do things... very very expensive chassis, but the look is great and it does dissipate a lot of heat so you can still interact with the chassis without burning yourself... obviously that isn't possible with this current box setup...

4) This was first and foremost supposed to be a single amplifier project just for my own personal use.  No commercial offering planned... however, if it is a killer amp and a viable product offering, it still needs to be able to commercialize it easily just in case... so do I keep it cheap in some areas for just the prototype in case we abandon it entirely and build additional prototype sets later with the adjustments in them or do you do it to this set of amps?  Do you try to cobble together off the shelf parts now to get something working, or do you blow the wad and get custom wound trannies for this to make it an ideal setup now knowing that you may not even keep the prototypes let alone do something commercial down the road?

5) again, these are supposed to be prototypes... but if they end up being the final amps that I keep for years to come and we don't get $500 each custom chassis (and the labor hours to re-wire into them), then these have to look good on prominent display at my place or it won't fly at all with the better half... and they have to be kid proof to a certain degree as well since the room they will be used in will likely have prying kid hands for the next number of years...

At this point, based on the little bit of listening I've been able to do, regardless of commercial future, I'm likely going to keep these as personal amps for a while...  so the heat issues and the mechanical noise from trannies needs to be fixed so we can move to the next step of tweaking parts and circuit, etc.

So, since the form factor and need to potentially re-wire are still up in the air, trying to do the inexpensive stuff first...  hacking up the wood boxes was the first approach before touching the top plate... With some metal mesh over the openings cut into the chassis, it would definitely be interesting looking...  again, I'd prefer not to have to drill out the top plate more, but may still have to...  at least early reports are that the heat is lowered a bit more...  still likely need more heat sinking capability for the regulated power supplies though...  

going to try to fix the cheaper power trannies from buzzing first before coughing up the cash for custom wound ones (i.e. $$$$ saved for now)...  I blew the budget on the output trannies as I figured they would have the most impacts on things....  I didn't expect the multiple Hammond power trannies to buzz and vibrate as much as they do.... .  hopefully that will get resolved soon to allow better evaluation of the amp's sound itself...  which so far is pretty darn good sounding, I must say....  I just needed the heat thing addressed so i could run them 24/7 to break them in and feel comfortable doing it... and reduce the mechanical noise a bit more... 95% of folks wouldn't even notice it... but it's a frequency and pitch that drives me batty...... 
« Last Edit: January 27, 2012, 08:48:42 AM by hometheaterdoc »
Shane Sangster
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Offline tmazz

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Re: New custom monoblock tube amps....
« Reply #39 on: January 27, 2012, 10:42:10 AM »
Shane didn't PS audio make a device that went in between the wall outlet and your amp was supposed to  eliminate transformer hum?
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Offline hometheaterdoc

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Re: New custom monoblock tube amps....
« Reply #40 on: January 27, 2012, 10:50:09 AM »
Shane didn't PS audio make a device that went in between the wall outlet and your amp was supposed to  eliminate transformer hum?

They may have in the past...  not on the current list of skus though... thanks for the suggestion...  it may come to that at some point....  but I'll hold Sol's feet to the fire first to fix the issue at the source before trying to put bandaids on it :)
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Offline richidoo

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Re: New custom monoblock tube amps....
« Reply #41 on: January 27, 2012, 11:24:12 AM »
It was probably a DC blocker, as DC will cause humming.

Hammonds are known to be noisy on occasion. All transformers hum to some degree, so it could be that mounting them on a large piece of thin metal is amplifying a small problem into a big one. When I press down on different parts of the top plate, the transformer hum lessens slightly, and increases when I release. That's what got me suspecting the vibe sound is outside the tranny, even if the origin of vibes is the tranny.  Since the tubes are also mounted to the same plate, isolating or bracing the tubes against the normal vibration of the transformers will also help with the tube microphonics.

Offline rollo

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Re: New custom monoblock tube amps....
« Reply #42 on: January 28, 2012, 07:18:27 AM »
   Looking good for a prototype. Interesting wood work. Isolate those trannies. A 10ga top plate may help What works very well are Ebony Pen blanks under the trannie. Like a RR track.
  Have fun good tings take time.


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Offline richidoo

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Re: New custom monoblock tube amps....
« Reply #43 on: January 28, 2012, 10:11:35 AM »
Supposedly BORG has rubber isolation mounts and grommets in the cabinet hardware section.

Article on tranny isolation:
http://www.siteswithstyle.com/VoltSecond/Foreplay_grommets/Foreplay_grommet.html

Offline richidoo

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Re: New custom monoblock tube amps....
« Reply #44 on: January 28, 2012, 02:50:27 PM »
Tubes are silent, the noise is from the transformers.