Promitheus TVC passive preamp anyone?

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rollo

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Re: Promitheus TVC passive preamp anyone?
« Reply #1100 on: 25 Feb 2007, 01:44 pm »
You guys are just going bonkers with the tweaks I think.......I was just thinking that if you dampen some vibration that escapes the trannies, it doesn't mean that you may impact a lot of the vibration that gets thru the chassis itself as in attachment point between tranny and structure. 

I am not one to judge really how well this stuff works as I never tried them, but I cant help but think its nuts....Everything has its own sympathetic vibration freq that is unique to all materials. Why not just figure out whats the freq of vibration range that is most noticeable coming from the trannie and then look for the material that best dampens it. (that is, if the vibrations they convey is volume and freq dependent...maybe its not (maybe its same freq but just more of it) and that makes it simpler).
   

   Whitese,

              Great idea, how do you do it? At this point we are having fun. We may be nuts, but that is part of the fun.
             Kidding aside, it is external and internal vibes that require attenuation. I put playsand on top of unit and vibrate box until sand gathers at resonance points [top] and then place weight at that spot. Turn it over and repeat process. As you know anything you do alters the sound in some way. By trying different materials and such by trial and error is fun and rewarding in most cases.
             I admit some tweaks are far fetched but again we enjoy the chase and learn from the experience. Did you wake up on the wrong side of the rock today?
       rollo

Whitese

Re: Promitheus TVC passive preamp anyone?
« Reply #1101 on: 25 Feb 2007, 03:07 pm »
lol..No I woke up on the right side...It was just a early morning general observation...I enjoy reading the trials and stuff, but it was just a thought that had come to me. I didnt mean as "you guys are nuts", more of laugh with you than at you remark.

I wasnt knocking the tweaking down, just being the voice of an almost non-tweaker sometimes.. And i know most of you have thick enough skin to absorb my slant..

If not, my bad.. :duh:

rollo

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Re: Promitheus TVC passive preamp anyone?
« Reply #1102 on: 25 Feb 2007, 08:32 pm »
Whitese,
              No offence taken at all just having a little fun. Sorry  if I made you feel that you offended anyone.
               Listen if you put your refrig. on brass cones and use a better powercord the beer will get colder. Oh did you get the orgone energy collection device or put a photo of yourself in the freezer yet? C'mon man what are you waiting for?
    Cheers rollo

Whitese

Re: Promitheus TVC passive preamp anyone?
« Reply #1103 on: 25 Feb 2007, 09:45 pm »
Whitese,
              No offence taken at all just having a little fun. Sorry  if I made you feel that you offended anyone.
               Listen if you put your refrig. on brass cones and use a better powercord the beer will get colder. Oh did you get the orgone energy collection device or put a photo of yourself in the freezer yet? C'mon man what are you waiting for?
    Cheers rollo

LOL..i put a pic of my wife in thge freezer though!

guest1632

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Re: Promitheus TVC passive preamp anyone?
« Reply #1104 on: 26 Feb 2007, 05:36 pm »
You guys are just going bonkers with the tweaks I think.......I was just thinking that if you dampen some vibration that escapes the trannies, it doesn't mean that you may impact a lot of the vibration that gets thru the chassis itself as in attachment point between tranny and structure. 

I am not one to judge really how well this stuff works as I never tried them, but I cant help but think its nuts....Everything has its own sympathetic vibration freq that is unique to all materials. Why not just figure out whats the freq of vibration range that is most noticeable coming from the trannie and then look for the material that best dampens it. (that is, if the vibrations they convey is volume and freq dependent...maybe its not (maybe its same freq but just more of it) and that makes it simpler).
   

   Whitese,

              Great idea, how do you do it? At this point we are having fun. We may be nuts, but that is part of the fun.
             Kidding aside, it is external and internal vibes that require attenuation. I put playsand on top of unit and vibrate box until sand gathers at resonance points [top] and then place weight at that spot. Turn it over and repeat process. As you know anything you do alters the sound in some way. By trying different materials and such by trial and error is fun and rewarding in most cases.
             I admit some tweaks are far fetched but again we enjoy the chase and learn from the experience. Did you wake up on the wrong side of the rock today?
       rollo

Hey Rollo,

Here's a simple tweak that I haven't seen mentioned here. I took off the knobs on the front of the box. Now, if your switches are directly mounted to the box, then use a nut driver or pliers, and carefully tighten the nuts til they don't turn any further. You don't have to go crazy here, maybe a quarter turn or so. Just til the nut stops turning. Then put the knobs back on, and listen. I was downright astonished at the difference. The sound came a little forward, not in a bad way, maybe it's that tube bloom that I've heard about but never experienced. The highs also smoothed out a little more. The attack on drums seemed a bit faster, maybe more dynamic in nature. The bass wasn't any stronger, yet it seems to be deeper somehow. 

I hooked up my "Purist" and while it is a good preamp, it is a night and day difference. Now, when I say that, I am not exaggerating in any sense of the word. It was a real letdown to go back to the "Purist." .

When I first got the Unit, I tighten up the various screws and also the RCA connectors on the back. About the only thing that wasn't real loose was the toggle switch. So this tweak is something that only requires your time.

Regards,
Ray 

Hajime Sato

Re: Promitheus TVC passive preamp anyone?
« Reply #1105 on: 27 Feb 2007, 09:03 am »
I know I'm WAY behind the curve, but I recently bought the Promitheus TVC from my friend and became a proud owner, so like to jump in :green:. I think mine is a relatively older unit: stereo single-ended model, wood chassis and stainless steel top plate.

I had an opportunity to listen to it in my system before I bought it, and it beat the preamp section of Krell KAV-300iL (I was using it as a preamp) in subjective S/N ratio and detail retrieval. This is a cliche, but when I switched to the TVC, it was as if a veil was lifted.

I had some hum noise initially, but reading this thread I changed the position of the TVC and rearranged the wires, and it was gone. Thanks guys for all the helpful hints! I think this little TVC is amazing in its clarity, microdynamics and low-level resolution.

After a few weeks, though, I began to miss the powerful bass that the Krell used to provide, and more importantly I notice some harsh glare in the highs with some recordings, especially when I turn up the volume. I'm thinking that the new active preamp may solve all these problems, and if possible I'd like to participate in the home trial. Any word on how this is turning out, and any other advice/suggestion will be appreciated.

Thanks and happy listening! :thumb:

FYI, my associated equipent are:
Ah! Njoe Tjoeb 4000 CD player with upsampler
McIntosh MC275 mkIV power amp
Totem Acoustic Forest speakers

guest1632

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Re: Promitheus TVC passive preamp anyone?
« Reply #1106 on: 27 Feb 2007, 11:51 am »
I know I'm WAY behind the curve, but I recently bought the Promitheus TVC from my friend and became a proud owner, so like to jump in :green:. I think mine is a relatively older unit: stereo single-ended model, wood chassis and stainless steel top plate.

I had an opportunity to listen to it in my system before I bought it, and it beat the preamp section of Krell KAV-300iL (I was using it as a preamp) in subjective S/N ratio and detail retrieval. This is a cliche, but when I switched to the TVC, it was as if a veil was lifted.

I had some hum noise initially, but reading this thread I changed the position of the TVC and rearranged the wires, and it was gone. Thanks guys for all the helpful hints! I think this little TVC is amazing in its clarity, microdynamics and low-level resolution.

After a few weeks, though, I began to miss the powerful bass that the Krell used to provide, and more importantly I notice some harsh glare in the highs with some recordings, especially when I turn up the volume. I'm thinking that the new active preamp may solve all these problems, and if possible I'd like to participate in the home trial. Any word on how this is turning out, and any other advice/suggestion will be appreciated.

Thanks and happy listening! :thumb:

FYI, my associated equipent are:
Ah! Njoe Tjoeb 4000 CD player with upsampler
McIntosh MC275 mkIV power amp
Totem Acoustic Forest speakers

Hi, Well, a few tweaks for you are in order if you wish to do them.

Go get some hardwooden 1/4 inch doweling. You want something like spruce, or oadk or maple, hardwood. You will need about 7 inches total. about 4/1/2 inches for the selector switch and 2/1/12 inches for the volume knob. Taking the lid off the top, loosen the small set screws towards the front of the case for both knobs. You will see 2 screws for each link set. 2 hold the knob shaft for the switch and 2 hold the extension shaft. Use a small screwdriver. These screws when tightened can be stripped easily. You will also have to use an allen wrench to loosen the 2 screws on each knob, so you can remove the extension shaft. You might measure them to make sure you have the right lengths. They may vary depending on where Nicholas mounted your switchs to the bottom of the wooden box. It's not as complicated as it may seem. Those extension shafts do ring. A wooden dowell won't ring nearly as badly.

Ray

launche

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Re: Promitheus TVC passive preamp anyone?
« Reply #1107 on: 27 Feb 2007, 03:06 pm »
Ray do you have any pics of this configuration?

Thanks

guest1632

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Re: Promitheus TVC passive preamp anyone?
« Reply #1108 on: 27 Feb 2007, 06:29 pm »
Ray do you have any pics of this configuration?

Thanks

Sorry, No I don't. I am a blind person. So that is why I gave a verbal description as to what to do.

Ray

gooberdude

Re: Promitheus TVC passive preamp anyone?
« Reply #1109 on: 27 Feb 2007, 07:41 pm »
I'll post some pics of this in a few days...i haven't swapped out the metal dowel rods but
plan to once i get my lazy butt to the hardware store.   someone should post a pic of the source selector knob isolation...


In the last week or 2 i've removed the metal lid of my TVC and installed some EAR Isodamp under the Source Selector switch mount.  Add to that the installation of the Ebony knobs, and i think my TVC sounds better than ever.

the knobs and Source switch mount made the biggest diff by far, removing the lid has no ill effects and i kinda detect a smoother presentation, but its not a truly noticeable tweak.   A whole group of bare wires inside my TVC touches the metal lid when its closed (the wires are run on top of one of the trannies)....peace of mind with it removed i guess.

My guess is swapping out the metal rods for wood ones will be audible, hopefully not a PITA tweak.


Hajime Sato

Re: Promitheus TVC passive preamp anyone?
« Reply #1110 on: 27 Feb 2007, 07:53 pm »
Hi, Well, a few tweaks for you are in order if you wish to do them.

Go get some hardwooden 1/4 inch doweling. You want something like spruce, or oadk or maple, hardwood. You will need about 7 inches total. about 4/1/2 inches for the selector switch and 2/1/12 inches for the volume knob. Taking the lid off the top, loosen the small set screws towards the front of the case for both knobs. You will see 2 screws for each link set. 2 hold the knob shaft for the switch and 2 hold the extension shaft. Use a small screwdriver. These screws when tightened can be stripped easily. You will also have to use an allen wrench to loosen the 2 screws on each knob, so you can remove the extension shaft. You might measure them to make sure you have the right lengths. They may vary depending on where Nicholas mounted your switchs to the bottom of the wooden box. It's not as complicated as it may seem. Those extension shafts do ring. A wooden dowell won't ring nearly as badly.

Ray

Thanks Ray,
I'm not really good with my hands so it seems daunting to me, but I'll look into it. Would it help to tame the harsh highs and bring back bass power, or is it more of a basic tweak that improves everything?

gooberdude

Re: Promitheus TVC passive preamp anyone?
« Reply #1111 on: 27 Feb 2007, 08:01 pm »
Hey Hajime,

is your TVC burned in all the way??

if the highs are harsh and the low end isn't there, you might have another problem or the TVC might
not work well in your system, dunno.

i don't think any of the simple tweaks listed here will cure big issues...just refining the presentation really.


matt

GHM

Re: Promitheus TVC passive preamp anyone?
« Reply #1112 on: 27 Feb 2007, 08:02 pm »
Hi, Well, a few tweaks for you are in order if you wish to do them.

Go get some hardwooden 1/4 inch doweling. You want something like spruce, or oadk or maple, hardwood. You will need about 7 inches total. about 4/1/2 inches for the selector switch and 2/1/12 inches for the volume knob. Taking the lid off the top, loosen the small set screws towards the front of the case for both knobs. You will see 2 screws for each link set. 2 hold the knob shaft for the switch and 2 hold the extension shaft. Use a small screwdriver. These screws when tightened can be stripped easily. You will also have to use an allen wrench to loosen the 2 screws on each knob, so you can remove the extension shaft. You might measure them to make sure you have the right lengths. They may vary depending on where Nicholas mounted your switchs to the bottom of the wooden box. It's not as complicated as it may seem. Those extension shafts do ring. A wooden dowell won't ring nearly as badly.

Ray

Thanks Ray,
I'm not really good with my hands so it seems daunting to me, but I'll look into it. Would it help to tame the harsh highs and bring back bass power, or is it more of a basic tweak that improves everything?


Hi,
Hajime Sato..You can easily get more bass and less harsh highs by just changing the source. The source is the key too getting the most out of a passive preamp. The better the source the better the sound. Most active preamps add their own spice to the music..which is fine if that's what you're after. I'm sure the tweaks have their place also, but nothing like changing the source. :wink:

Change the source and you'll understand what I mean. In a transparent system, sources make a HUGE difference..yours seems transparent enough to hear the benefits.

guest1632

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Re: Promitheus TVC passive preamp anyone?
« Reply #1113 on: 27 Feb 2007, 08:18 pm »
I'll post some pics of this in a few days...i haven't swapped out the metal dowel rods but
plan to once i get my lazy butt to the hardware store.   someone should post a pic of the source selector knob isolation...


In the last week or 2 i've removed the metal lid of my TVC and installed some EAR Isodamp under the Source Selector switch mount.  Add to that the installation of the Ebony knobs, and i think my TVC sounds better than ever.

the knobs and Source switch mount made the biggest diff by far, removing the lid has no ill effects and i kinda detect a smoother presentation, but its not a truly noticeable tweak.   A whole group of bare wires inside my TVC touches the metal lid when its closed (the wires are run on top of one of the trannies)....peace of mind with it removed i guess.

My guess is swapping out the metal rods for wood ones will be audible, hopefully not a PITA tweak.



Hi Gooberdude,

On those wires, you might try carefully to move them off the transformers. If you have to loosen one of the bolts holding down the transformer to do that, that should work out aok. Is yours with the wooden bottom too?

Ray

gooberdude

Re: Promitheus TVC passive preamp anyone?
« Reply #1114 on: 27 Feb 2007, 08:45 pm »
Hey Ray,

Mine is an older version with the wood bottom and single volume knob.

With the lid off, the bundle of wires doesn't actually touch the transformer...it goes right over top about
1 cm above.   BUT, when the metal lid is installed, it squashes the wires onto the tranny - which makes my inner 'phile twitch nervously since the wires are now touching the tranny and the metal lid.

If there was another 1' of length to the wires i'd re-route them, i'm not about to muscle anything inside the cigar box though...


guest1632

  • Guest
Re: Promitheus TVC passive preamp anyone?
« Reply #1115 on: 27 Feb 2007, 09:10 pm »
Hey Ray,

Mine is an older version with the wood bottom and single volume knob.

With the lid off, the bundle of wires doesn't actually touch the transformer...it goes right over top about
1 cm above.   BUT, when the metal lid is installed, it squashes the wires onto the tranny - which makes my inner 'phile twitch nervously since the wires are now touching the tranny and the metal lid.

If there was another 1' of length to the wires i'd re-route them, i'm not about to muscle anything inside the cigar box though...



Understood there Gooberdude,

That's why I suggested what I suggested. Also, look see if any of the screws are showing working there way through the box. If so, you will have to get some finishing washers like the ones on the top of the case. That will tighten down the transformers, and they might even sound better.

Ray

gooberdude

Re: Promitheus TVC passive preamp anyone?
« Reply #1116 on: 27 Feb 2007, 10:03 pm »
i understand now, kind of a 'jump rope' idea to get the wires out of harms way.
The trannies are glued to the bottom of the chassis with some black gunk, no idea what it is...some
kind of damping material that looks to have been liquid at some point.   Unless i order Black hole pads,  unscrewing or removing the trannies isn't in the works just yet.

Your suggestion of using other washers is a great idea too...i have several of them left over when i removed a couple of chassis screws that weren't needed.   At some point i'd like to replace all the screws & nuts with plastic ones.

I haven't checked all of them, but the screws which held down the Source Selector knob where loose when i 1st opened to the TVC.  those probably see a lot of stress due to their job though.   considering the RCA's occasionally get loose too, it might not be a bad idea to check all the screw down connections every so often.    you mentioned tightening the Volume knob nut and that got me a thinkin'

Since i set the TVC on footers, i wonder if swapping out all the washers that are on the outside of the TVC with heavier ones might change something.    Unscrew a couple of screws & hold 2 or 3 of these washers in your hand...when they hit one another they have a really high pitched sound.

all in the name of tweakin'!

matt

Hajime Sato

Re: Promitheus TVC passive preamp anyone?
« Reply #1117 on: 27 Feb 2007, 11:44 pm »
Ray, Matt and GHM,

Thanks for all the advice! I really appreciate it. I'll certainly look into your suggestions.

Just to clarify, I'm very happy with the performance of the TVC. I can actually accept the slight loss of (subjective) bass power as a worthy trade-off for getting extra clarity and detail. I wouldn't be surprised if someone told me I had too much bass before. As for the glare, it only happens wih a few CDs and only when I crank up the volume.

As for break-in, I don't know exactly how long my friend had it for, but I've been using it fairly regularly (avg. 4 hours a day) for the past month. I wonder if I need to break in the "high" volume setting that I use only occasionally. I'll try to break-in the higher volume settings using the FM radio (with power amp turned off).

Also, Nicholas has informed me that I'm on the list for the active preamp home trial. I look forward to it.

guest1632

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Re: Promitheus TVC passive preamp anyone?
« Reply #1118 on: 28 Feb 2007, 12:09 am »
Ray, Matt and GHM,

Thanks for all the advice! I really appreciate it. I'll certainly look into your suggestions.

Just to clarify, I'm very happy with the performance of the TVC. I can actually accept the slight loss of (subjective) bass power as a worthy trade-off for getting extra clarity and detail. I wouldn't be surprised if someone told me I had too much bass before. As for the glare, it only happens wih a few CDs and only when I crank up the volume.

As for break-in, I don't know exactly how long my friend had it for, but I've been using it fairly regularly (avg. 4 hours a day) for the past month. I wonder if I need to break in the "high" volume setting that I use only occasionally. I'll try to break-in the higher volume settings using the FM radio (with power amp turned off).

Also, Nicholas has informed me that I'm on the list for the active preamp home trial. I look forward to it.

If you have a CD or DVD player hooked up, then when not in use, just leave the player turned on with no CD playing, and when you're not using your system, turn the volume up to max minus a couple of clicks. Rollow seems to feel that there is a breakin at 100 hours and the final one at about 480 hours. So thry that.

My new one have a pad under each tranformer, use finishing washers underneath each of the 8 places. two will be under each tranformer, and 2 will be under each bracket holding each switch. You might want to tighten up the nuts on the switches on each bracket.

Ray

Hajime Sato

Re: Promitheus TVC passive preamp anyone?
« Reply #1119 on: 1 Mar 2007, 12:42 am »
Ray, thanks again. I'll try that break-in method and see what happens.