Hey guys,
Need help. I have a 26 preamp now. It's very microphonic. Some tube dampers have helped, but not enough. So, I am looking at using some cones underneath, to help with reducing vibration. I used to see wood (ebony?) cones, but I can't seem to find them. Anyone know of any place that has them, for "cheaper" perhaps?
I used Vibrapods, and they sucked. So, I'll experiment with wood next. :duh
Thanks.
Shek
I'd go with Herbie's isocups with supersonic hardballs.
He's got ebony balls you can try with the isocups too, as well as ebony hemispheres you could try by themselves, but I'd recommend going with the cups + balls.
With so many options, I'm curious as to why you would get a pre-amp that cannot stand on its own 4 feet?
What does it say about the build quality and control?
Shek,
Why do you say the pre is microphonic? What is this based on?
With all of your inputs turned off and the pre and power amps on tap on the tubes and the case. if you hear thumps when you tap on the tubes, but not when you tap on the case then it is the tubes themselves that are microphonic and I'm not sure that changing the underpinnings will help that at all. If taps on the case are getting through to the speakers then draining or damping the case may be in order.
If that it the case then you have two general options either drain the vibrations from the case using some kind of mass coupling device like cones or damping the case by placing on some kind of visio-elastic material, like sorbothane puck. With either type there are all kinds of options, and the best thing might be to borrow and try various devices that are hiding in the castoff draws of various audiophile buddies and fellow club members.
But I would start by at least trying one of each type to try and get a direction to go for further experimentation.
Try loosening all the screws holding everything down. Including chassis
and transformer. Whats happening is all the energy is getting bottled up. Whatever those screws are holding down is not allowed to dissipate vibration. The energy looks for the easiest (loosest) outlet and its probably your tube sockets.
Remember those transport screws in 80s cd players? Well that was ahead of its time. Everything gets shipped too tight. Should be released at destination.
You want to equalize the vibration pressure in the chassis. That is basically what happens.
Quote from: goldlizsts on September 18, 2014, 12:17:08 PM
I used Vibrapods, and they sucked. So, I'll experiment with wood next. :duh
Some thoughts...
Did you load the vibrapods correctly? Like any elastic damper they need to have enough weight applied to work. They need to be squished firmly, otherwise they bounce like rubber and will hurt the sound quality. When loaded, the material turns very viscous and eats vibration, not bouncing around. There are several durometers available, each requires a different weight per pod. See the manual:
http://www.vibrapod.com/PDF/manual.pdf
Listen to the microphonic sound, try to hear a frequency, check it on a piano, or online keyboard. Target your damping to that specific freq.
http://en.wikipedia.org/wiki/Piano_key_frequencies
Metal chassis surfaces will ring, and could be the direct source of the microphonic vibrations, especially if they are in the midrange or higher frequency range where only metal will ring. There could be some parts inside the tube that are resonating also, but it will still be evident in the tone of the ring. Apply damping materials to the interior surfaces of the metal to make the box quiet. Dynamat.
Experiment with Sorbothane. This is what Vibrapods are made of, it is the best damping material available. Buy sheets of it on Amazon.
http://www.amazon.com/s/ref=bl_sr_industrial?ie=UTF8&field-brandtextbin=Isolate+It%21&node=16310091
there are different thicknesses and durometer. You can cut your own pieces to suit your application. This allows using very small pieces, which ensures adequate loading. You can add more small pieces if the loading per piece is too high.
Read sorbothane design guide to determine the size and durometer of the pieces needed for your preamp.
http://www.sorbothane.com/Sorbothane-Design-Guide101409.pdf
To increase loading, use a combination of smaller pieces, fewer pieces, and lower durometer. Too much loading will reduce damping but not damage SQ. Too little damping will dull the sound. This is the most common complaint of people who try damping without applying enough load and quickly go back to "draining" techniques.
You can only damp the glass of a tube, not the internal elements directly. You have to damp everything around the tube to quiet the internal tube parts.
Here is another trick. The 26 tube is very microphonic and sensitive in a line stage circuit. There is really not much you can do about it. The design itself is critical as with any DHT in a linestage.
Are you getting a lot of noise at idle with no music playing? Does it get worse when playing music at higher volume and are the tubes exposed. With no music playing, tap on the tube, if it rings through the speaker, the cover outlined below will help with that.
Exposed tubes are sensitive to airborne vibrations. Especially DHTs. One trick is to get some acrylic tube big enough to fit over the tube or build a box to fit over them. Use 1/4" minimum. It HAS to have a top on it as well or vibration can still get in. You can drill some vent holes in the BACK side of it depending on how hot the tubes get. I mention acrylic so you can still see the tubes and it has excelllent vibration control properties.
This cover will stop airborne vibrations from getting into the envelope of the tube.
The only other method for this type of tube is to design a hammock mounting system. The trick is to release any and all tension of the tube socket as possible. Not easy but can be done.
Oh....and you want to use heavy "soft damping" on the chassis with decoupling rather than coupling. Herbies Tenderfeet are an excellent option. Dont use wood.
Quote from: Response Audio on September 20, 2014, 09:05:17 AM
Here is another trick. The 26 tube is very microphonic and sensitive in a line stage circuit. There is really not much you can do about it. The design itself is critical as with any DHT in a linestage.
Are you getting a lot of noise at idle with no music playing? Does it get worse when playing music at higher volume and are the tubes exposed. With no music playing, tap on the tube, if it rings through the speaker, the cover outlined below will help with that.
Exposed tubes are sensitive to airborne vibrations. Especially DHTs. One trick is to get some acrylic tube big enough to fit over the tube or build a box to fit over them. Use 1/4" minimum. It HAS to have a top on it as well or vibration can still get in. You can drill some vent holes in the BACK side of it depending on how hot the tubes get. I mention acrylic so you can still see the tubes and it has excelllent vibration control properties.
This cover will stop airborne vibrations from getting into the envelope of the tube.
The only other method for this type of tube is to design a hammock mounting system. The trick is to release any and all tension of the tube socket as possible. Not easy but can be done.
Oh....and you want to use heavy "soft damping" on the chassis with decoupling rather than coupling. Herbies Tenderfeet are an excellent option. Dont use wood.
Thanks Bill. At idle, it's really stable, only some slight hiss out of the box, and only when I'm like 2 ft. in front of the speaker. Only when I "touch" the chassis, etc. that the microphonics really act up. The 26 tube by itself is microphonic, that I've learned. Right now, I have tube dampers on the 26, GZ34, and another.... The sound seems fine.
I had been told about a box over it. I'm not an extreme nut case yet, so that's not being considered. I just thought I'd put some "footers" underneath to fine-tune the sound, which is excellent now. I had vibrapods directly put underneath (only the flat rounds ones, but not the cones). The sound isn't really impressing on my ears. So, I just thought of "experimenting" with wood..... I was "warned" that vibrapod not being good, and it didn't please for sure.
Hey Shek,
I'm not only using Herbies Tenderfeet under my Havana dac but Steve also recommended (and I'm using) his Supersonic Stabilizer top weight that also counteracts microscopic tube vibrations that you're feeling at touch to the chassis. You might need to stack a couple. http://herbiesaudiolab.net/stable.htm
Cheers,
Robin
Hey Shek
Come on over with the preamp. I have loads of stuff to fool with. Ebony, brass, Vibrapods, Sand boxes, tube dampers, chassis vibration, Pon-Tunes, Magnetic footers, etc.
We will get it right and have some fun doing it.
charles
SATFRAT????
WTF??
Did someone steal his account and post as "himself" or is the real SATFRAT back in action again?
Inquiring minds want to know what's been happening for the last 2-3 years?
Quote from: Packfill on September 18, 2014, 06:10:13 PM
With so many options, I'm curious as to why you would get a pre-amp that cannot stand on its own 4 feet?
What does it say about the build quality and control?
Well, I'm not sure if you've heard a 26 preamp perform; you'd have to experience a 26 tube preamp. The 26 tube is generally said to be more microphonic than other tubes. IF I had been content with other preamps (if I never heard of the 26 tube), then you're absolutely justified in critiquing the situation. But, I took the plunge. :yay2:. Thanks.
Quote, I'm curious as to why you would get a pre-amp that cannot stand on its own 4 feet?
Because that's what an audio neurotic does :D
Quote from: Response Audio on September 22, 2014, 07:10:48 PM
Quote, I'm curious as to why you would get a pre-amp that cannot stand on its own 4 feet?
Because that's what an audio neurotic does :D
Ditto :yay2: :yay2: :yay2: :yay2: :yay2: :yay2: :yay2: :yay2: :yay2: :yay2:
Not tooooooo neurotic tho! A little fanatical may be. :rofl:
Incidentally, over last night and this morning, I experimented a little. Picked up a sponge type foam packing piece, 4/5" thick (not the particle type), and put it underneath the 26 pre. Similar to using the Vibrapods, slightly less sucky. This morning, took the foam out. Much more musical. Harmonically richer the way I'm used to.
A friend suggested putting granite squares underneath. I actually have a couple, but need couple more, I picked up at Home Depot, 3" square type. May be I'll put them directly underneath the 26, see how it goes. Right now, I have those squares underneath each of the rack legs, on top of the carpet.
Continue with my little game. :duh
I've got a neat little isolation system that Dave had given me a few years back. It consists of 3 rubber balls and 3 cups for them to rest in. The balls can roll a bit in the cups, but they do "Center" themselves. Let me know if you're interested, and we can figure out how to get them to you.
Quote from: Barry (NJ) on September 23, 2014, 12:44:01 PM
I've got a neat little isolation system that Dave had given me a few years back. It consists of 3 rubber balls and 3 cups for them to rest in. The balls can roll a bit in the cups, but they do "Center" themselves. Let me know if you're interested, and we can figure out how to get them to you.
Hi Barry,
I'd love to get hold of them. Tweaks like this is easier and more fun.....
I have to deliver 2 issues of a HK Audio magazine to Karl (Bedminster). I resisted to spend the $12 (!) toll until I have a more productive trip crossing the GW. Now, I have a good reason to do that. I should now make a trip to drop by your place, then his.... or vice versa.
Let's arrange a convenient time. I am aware of the "cup" kind of setup. The Vibrapod people recommend using their cones with their flat/cups, but I just was taken aback by the lousy sound of the flat ones. A friend told me that Vibrapods or plastics they suck.... So far, I'm better of without Vibrapods....
Shek
Well if you were taking the trip during the day on a M-F I can bring them with me to work, right off 95 in Teaneck (https://www.google.com/maps/place/500+Frank+W+Burr+Blvd,+Teaneck,+NJ+07666/@40.8728072,-74.0060006,15z/data=!4m2!3m1!1s0x89c2f735f0c9834d:0x7660e4be06d824a8) Or I'm home most evenings and weekends ;)
shek,
Don't forget the wood.
I have a feeling wood might work best with the microphonic DHT 26 tube. A soft wood.
I have a phono pre that uses semi circles made of wood for feet.
But I think the microphonics are just going to be something you have to live with. Buy lots of 26 tubes on ebay, you may find a quiet pair. Microphonics are a small price to pay for the sound of a great sounding DHT tube, or try the 6c45pi tube!
Quote from: topround on September 23, 2014, 04:31:39 PM
shek,
Don't forget the wood.
I have a feeling wood might work best with the microphonic DHT 26 tube. A soft wood.
I have a phono pre that uses semi circles made of wood for feet.
But I think the microphonics are just going to be something you have to live with. Buy lots of 26 tubes on ebay, you may find a quiet pair. Microphonics are a small price to pay for the sound of a great sounding DHT tube, or try the 6c45pi tube!
Yes Signore, I am "living" with the microphonics, but just am "tweaking" it where I can. Someone from Canada just also advised me to "loosen" (somewhat) the screws on the chassis.... that should help, he said. will see.
Another friend just showed me how to make my own Herbie's, O Rings and washers from Home Depot.....
The sound of the 26 pre is wonderful, guys. I guess because of the microphonics issue, nobody really put money on it. Now, at least within my circle, we became aware of it, and benefiting from the fantastic soundstage and presentation. I haven't heard as many amps and preamps as you guys. But, for what I know, this IS the best.
Thanks.
Quote from: goldlizsts on September 23, 2014, 05:17:12 PM
Quote from: topround on September 23, 2014, 04:31:39 PM
shek,
Don't forget the wood.
I have a feeling wood might work best with the microphonic DHT 26 tube. A soft wood.
I have a phono pre that uses semi circles made of wood for feet.
But I think the microphonics are just going to be something you have to live with. Buy lots of 26 tubes on ebay, you may find a quiet pair. Microphonics are a small price to pay for the sound of a great sounding DHT tube, or try the 6c45pi tube!
Yes Signore, I am "living" with the microphonics, but just am "tweaking" it where I can. Someone from Canada just also advised me to "loosen" (somewhat) the screws on the chassis.... that should help, he said.
Thanks.
That Canadian was Mr Fusey :thumb:
Quote from: Barry (NJ) on September 23, 2014, 01:53:36 PM
Well if you were taking the trip during the day on a M-F I can bring them with me to work, right off 95 in Teaneck (https://www.google.com/maps/place/500+Frank+W+Burr+Blvd,+Teaneck,+NJ+07666/@40.8728072,-74.0060006,15z/data=!4m2!3m1!1s0x89c2f735f0c9834d:0x7660e4be06d824a8) Or I'm home most evenings and weekends ;)
May be this coming Sunday I can come around to your place, then Karl's or Peter's to drop off a couple of magzines for Karl.... What's the better/best time Sunday? Thanks.
Can't fight City Hall syndrome now. I'm going to live with the microphonics "as is", since it's somewhat stable situation as long as I don't tap/rock the platform/chassis.
I've played with "doctoring" the sound quality. In the end, I think I like it "as is" also, without any Vibrapods, etc., underneath. The Vibrapods killed the sound quality IMO. The foam was slightly better, but.... still the sound didn't thrill. Also, I came across some ceramic door handles/knobs the other day. I took out the screws, and stuck them underneath the amp. Believe it or not, the sound was pretty good. Shiny, punchy.... But, I still found it not that musical to my taste. If you twist my arm and choose I'd take the ceramic door handles/knobs.
WITHOUT anything, the sound is actually MORE organic, more musical to my taste. I was told that wood may be THE answer. I'm trying to get someone to "make" some Ebony cones for me.
NO Herbies. They're too pricey. I actually bought some parts from Home Depot, see if I can make something similar, O Rings and Washers, from the Plumbing department. Didn't go through with it. I am staying with the teflon tube dampers from eBay. Cheap enough.
All in all, without anything underneath, the sound is more preferred. Is this what they "the more they change, the more they don't change..."? :duh
It makes sense that different footer will effect the sound but have no effect on the airborne microphonics. If you get a chance find something, anything, that will cover the tubes. Do you have an aquarium laying around the house that will cover the preamp? Cardboard tube? Anything just to experiment. You will be amazed of what this will do to control airborne vibrations from getting into the glass with no ill effects (no effects at all) on sonics. If you find that works, then you can seek out a permanent, more feasible solution such as an acrylic cover for the tubes.
Don't waste your time trying to put stuff on the tubes or under the chassis to control the airborne stuff.
Just my 2 cents (or is it $2 these days)
Quote from: Response Audio on September 28, 2014, 08:01:43 AM
It makes sense that different footer will effect the sound but have no effect on the airborne microphonics. If you get a chance find something, anything, that will cover the tubes. Do you have an aquarium laying around the house that will cover the preamp? Cardboard tube? Anything just to experiment. You will be amazed of what this will do to control airborne vibrations from getting into the glass with no ill effects (no effects at all) on sonics. If you find that works, then you can seek out a permanent, more feasible solution such as an acrylic cover for the tubes.
Don't waste your time trying to put stuff on the tubes or under the chassis to control the airborne stuff.
Just my 2 cents (or is it $2 these days)
Thanks Bill. That certainly is worth trying. Shouldn't be too painful. I will look for something to cover it up. Only thing otherwise thinking is that I'll probably make some "holes" for ventilation..... since the GZ34 gives off much heat (most of the heat for this pre).
'Nuf playing with footers underneath. So far, not impressed with foam, Vibrapod, ceramic spikes, or granite tiles (they all SUCK!). WITHOUT anything underneath, the pre sounds best, most musical, warm.... more lower frequencies. A friend told me wood'd the best. So, I'm waiting for another friend to make me some Ebony wood cones. Microphonics are tolerable, but WILL look into covering it up on top.
Chapter closed! :rofl:
Quote from: goldlizsts on September 28, 2014, 07:08:27 AM
I took out the screws, and stuck them underneath the amp. Believe it or not, the sound was pretty good.
What did it do for the Microphonics? If you like that sound do it to your source if it's digital. This works better for sound.
What you got (in order) is the source bottled up, the preamp released and the amp bottled up. Take the tension off the source or amp too. Preferable the source. then do the amp after awhile if you like.
Then release all the screws in your outlets. Electricity is vibration. You heard the preamp released so you know it's not fake. Whether you like it
or not is up to you.
we all have a loose screw!
You need at least a 1000 posts to get the "loose screw" designation here.
:rofl:
Quote from: Werd on October 01, 2014, 06:55:41 AM
You need at least a 1000 posts to get the "loose screw" designation here.
:rofl:
I thought you needed a loose screw to qualify for a login. :rofl: :rofl: :rofl:
Quote from: tmazz on October 01, 2014, 07:50:08 AM
Quote from: Werd on October 01, 2014, 06:55:41 AM
You need at least a 1000 posts to get the "loose screw" designation here.
:rofl:
I thought you needed a loose screw to qualify for a login. :rofl: :rofl: :rofl:
You are just a lose screw around here kid. :rofl: Stick around there ain't no fancy doctor that can you help now.
Quote from: Response Audio on September 28, 2014, 08:01:43 AM
It makes sense that different footer will effect the sound but have no effect on the airborne microphonics. If you get a chance find something, anything, that will cover the tubes. Do you have an aquarium laying around the house that will cover the preamp? Cardboard tube? Anything just to experiment. You will be amazed of what this will do to control airborne vibrations from getting into the glass with no ill effects (no effects at all) on sonics. If you find that works, then you can seek out a permanent, more feasible solution such as an acrylic cover for the tubes.
Don't waste your time trying to put stuff on the tubes or under the chassis to control the airborne stuff.
Just my 2 cents (or is it $2 these days)
My Fender bass amp uses metal covers on the pre amp tubes to help with this. It's probably the best solution for a bass amp. Not sure about home pre though?
QuoteMy Fender bass amp uses metal covers on the pre amp tubes to help with this. It's probably the best solution for a bass amp. Not sure about home pre though?
This would be a perfect solution for a preamp. However, they don't make commercial covers for the 26 tube and even if they did I wouldnt want an ugly metal cover hiding my cool looking DHTs.
This is what I would use :D With a top of course.
http://www.delviesplastics.com/mm5/graphics/00000001/acrylic_tube_1 (http://www.delviesplastics.com/mm5/graphics/00000001/acrylic_tube_1)
(http://www.delviesplastics.com/mm5/graphics/00000001/acrylic_tube_1)
Would there need to be a mechanism holding the cover in place too on the preamp?
QuoteWould there need to be a mechanism holding the cover in place too on the preamp?
No. Just a small hole in the back side for some heat escape. You simply want to deflect airborne vibrations from hiting the glass of the tube.
Quote from: Response Audio on October 01, 2014, 09:51:59 AM
QuoteWould there need to be a mechanism holding the cover in place too on the preamp?
No. Just a small hole in the back side for some heat escape. You simply want to deflect airborne vibrations from hiting the glass of the tube.
Believe it or not, Bill, I picked up a "papaya" packing cardboard box yesterday on the street (they sell lots of fresh fruits on the street in Chinatown here, so I spotted the crate box and measured it before grabbing it from the merchant), (almost) perfect fit on top of the preamp, bright orange color too, with "holes" prepunched for me (good ventilation). I tidied it up last night, and put it on this morning for a listening session. Psychology or what, I thought the sound is a little cleaner, better focus/imaging which the 226 tubes deliver very well (why we fell for it in the first place).
This crazy hobby :duh :rofl: :drool: :yay2:.
Skek, it must be the "quantum vibrations" of the papaya oils deposited in the cardboard during shipping that are counteracting the airborne tube microphonics. I would snatch up as many of those magic papaya boxes as you can. With an audiophile breakthrough like this you can probably get at least $1500 a piece for them on ebay. :rofl: :duh :rofl:
.... Maybe even more if you cryo the boxes first. :roll:
A friend of mine has been using a fruit box as speaker cabinet for some very expensive full range drivers for several years, and he is a master woodworker! So there must be something to this fruit box thing!
Quote from: richidoo on October 05, 2014, 07:50:44 PM
A friend of mine has been using a fruit box as speaker cabinet for some very expensive full range drivers for several years, and he is a master woodworker! So there must be something to this fruit box thing!
I think we have all seen stranger things during our time in this hobby. 8)
Quote from: tmazz on October 05, 2014, 01:46:10 PM
Skek, it must be the "quantum vibrations" of the papaya oils deposited in the cardboard during shipping that are counteracting the airborne tube microphonics. I would snatch up as many of those magic papaya boxes as you can. With an audiophile breakthrough like this you can probably get at least $1500 a piece for them on ebay. :rofl: :duh :rofl:
.... Maybe even more if you cryo the boxes first. :roll:
Darn good idea!!!!!!!!!! :yay2: Great way to recoup some of the money I've dumped in audio. :beer:
Here's my motto: Cryo so you don't cry o'er it! :rofl:
Now if they could only make these fruit/vegetable boxes clear :duh Maybe that could be an available option :rofl:
Rejoinder!!!!!!!!
A friend in CA just sent me a set of cones made from Ebony wood (DIY). I was trying to get a friend of his to make me some.... But, the wood is hard to come by, he said, so he sent me a set in the meantime. WOW! What can I say! WOOD is the only way I suppose. So far, I've used rubber (Vibrapods), granite squares, etc., etc. They all sucked. The main issue was the bad tonality they gave.
I was very, very pleasantly surprised at these Ebony cones under the preamp. The bass became firmer, more potent. There's more shine up there also because of a "cleaner" sound? Most critically, the musicality was not compromised at all (those other toys did damage, IMO). :drool:
The 26 is not microphonic if you build the preamp with anti-vibration mounting for the tube. Mine is dead quiet.
(http://i1243.photobucket.com/albums/gg559/Quagmire22/26PreampBatteryunderL1676_zps5a57afcb.jpg) (http://s1243.photobucket.com/user/Quagmire22/media/26PreampBatteryunderL1676_zps5a57afcb.jpg.html)
The 26 is mounted on sub assembly of two pieces of 4mm aluminum sandwiching a Soundcoat sheet, with Deflex bushings mounting the frame to wooden supports which are then mounted to the aluminum chassis. A teflon tube socket completes the mounting scheme. The series of dissimilar materials plus the massive sub-assembly means zero microphonics issues.
Now, if you have a bad tube, no amount of engineering can fix that, it can be microphonic with no provocation at all. Have you tried substituting different tubes? Also ST types have more internal support than balloon types, so using an ST might help if your current tubes are balloons. I prefer the sound of balloons, however (a little warmer).
Quote from: Maxamillion on October 21, 2014, 07:29:48 AM
The 26 is not microphonic if you build the preamp with anti-vibration mounting for the tube. Mine is dead quiet.
(http://i1243.photobucket.com/albums/gg559/Quagmire22/26PreampBatteryunderL1676_zps5a57afcb.jpg) (http://s1243.photobucket.com/user/Quagmire22/media/26PreampBatteryunderL1676_zps5a57afcb.jpg.html)
The 26 is mounted on sub assembly of two pieces of 4mm aluminum sandwiching a Soundcoat sheet, with Deflex bushings mounting the frame to wooden supports which are then mounted to the aluminum chassis. A teflon tube socket completes the mounting scheme. The series of dissimilar materials plus the massive sub-assembly means zero microphonics issues.
Now, if you have a bad tube, no amount of engineering can fix that, it can be microphonic with no provocation at all. Have you tried substituting different tubes? Also ST types have more internal support than balloon types, so using an ST might help if your current tubes are balloons. I prefer the sound of balloons, however (a little warmer).
Of course, your set was built like a tank? I was told the 26 tube is by itself more microphonic, so.... here and there I'd have a "wound" resonant kind of sound. It would get to moderately loud. I would shut down the system. I have no idea, it could be because my building was vibrating.... I'd turn it back on, and most of the time I wouldn't have the resonance anymore.
I actually have another set of 26 tubes I haven't put in (using 226 now). Will experiment.
I look forward to hear YOUR 26. I might end up sticking it under my coat and walk out of your house... Or, leave mine there in its stead, so nobody would notice yours is missing.... Nah, NO WAY I'll bring mine there. It's tooooo damn heavy to lug around to begin with. It's even heavier than my power amp I think...... The transformers probably have big lead pieces in them. :rofl: