Help needed to upgrade the capacitor in OTL tube amp
Sep 9, 2012 at 2:09 PM Post #91 of 113

WALL-E

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Just waiting for a output caps to arrive with some hook-up wires and bypass caps to complete all the parts I need to mods this amp.
wink.gif

 

 
 
All complete and ready to go!
 
Oct 6, 2012 at 7:13 PM Post #92 of 113

WALL-E

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It took awhile to complete all parts and find some time to do this mods but finally I did it.
 

 
265uf  per channel
 

 
The DK339
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Oct 10, 2012 at 6:08 PM Post #93 of 113

telecaster

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Wondernice! I love it WALL-E good job!
 
 
Oct 11, 2012 at 7:10 PM Post #95 of 113

WALL-E

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Indeed, Wow! Very clean job, I love it. I can't even tell what you modified, but I have a feeling it's everything. It does look glorious, anyways. Any audible difference?
 
Oh and have you got a picture of before, just for fun?


Yeah it looks like but some things has not been changed, all those things make noticeable, measurable and audible difference, but the sound of this amp is heavily dependent by the choice of tubes,  with good one even unmodded sound very well. First of all, the dynamic has improved and bass extension, much lower end, tight bass, the sound is more clearer it has more details but still retained the warm tubey sounding.
 
more details about the amp can be find on this thread     http://www.head-fi.org/t/502306/dark-voice-339/1095
 

 
                              before                                                                            after
 
Kim your Millett "Starving Student" Hybrid amp looks really stunning! I can only imagine, how much work and effort you had to put into this project.
 
Oct 11, 2012 at 10:53 PM Post #96 of 113

KimLaroux

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Thanks, but my starving student is child's play compared to what you did to your Dark Voice, and it probably doesn't sound even remotely as good.
 
I'm really speechless. You managed to upgrade it while at the same time making it look better. And you seem to have picked the upgrade parts with care, giving more credit to their specifications than to their brands. I'll take your experience as a lesson. I went for brands with my SSMH and the result is not very good. I think the capacitors I used in my power supply have too high ESR. I have 10 420µf of capacitance on the power rails, but I still have a lot of background noise. Makes me sick just to think about it. The problem is that most "boutique" brands don't have those specs in their datasheet. How did you go about selecting the right parts?
 
Another thing I'm curious about, is the enclosure of the Dark Voice a ferrous material? i.e. will a magnet stick to it? I'm asking because my experience with different enclosure material is pushing me to conclude that the only real way to shield an audio circuit is to use a ferrous enclosure, like steel. And something tells me the Dark Force has a steel enclosure.
 
Oct 12, 2012 at 4:48 PM Post #97 of 113

WALL-E

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Thanks, but my starving student is child's play compared to what you did to your Dark Voice, and it probably doesn't sound even remotely as good.
 
I'm really speechless. You managed to upgrade it while at the same time making it look better. And you seem to have picked the upgrade parts with care, giving more credit to their specifications than to their brands. I'll take your experience as a lesson. I went for brands with my SSMH and the result is not very good. I think the capacitors I used in my power supply have too high ESR. I have 10 420µf of capacitance on the power rails, but I still have a lot of background noise. Makes me sick just to think about it. The problem is that most "boutique" brands don't have those specs in their datasheet. How did you go about selecting the right parts?
 
Another thing I'm curious about, is the enclosure of the Dark Voice a ferrous material? i.e. will a magnet stick to it? I'm asking because my experience with different enclosure material is pushing me to conclude that the only real way to shield an audio circuit is to use a ferrous enclosure, like steel. And something tells me the Dark Force has a steel enclosure.

 
That is true most of manufactures don't have ESR in their datasheet. Before choosing a capacitor, it is worthwhile to check spec at angle of ESR and ripple current often higher voltage capacitor has lower ESR then cap on the lower voltage.

I am familiar with some brands like wima,or mundorf used it before, especially mundorf are very good sounding caps, I planned to use the mundorf 4 pole caps in power supply but due to the high price I had to find something similar, Kendeil was just right had everything what I need.

Background noise is the bane of almost all DIY'ers who build their amplifiers.The source of hum,noise can be anywhere, it could be power supply  but very often is the ground issue,e.g too many ground points can make ground loops, try to avoid it, ground should be as close to the signal circuits as possible, use only one point "star grounding" to connect the signal grounds to supply ground, try and keep the connection as short as possible.These are standard practices, but  proper grounding is more like kind of art.

The enclosure is made from iron or steel the magnet will stick to it.
 
Oct 13, 2012 at 9:43 PM Post #98 of 113

tomb

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Quote:
Thanks, but my starving student is child's play compared to what you did to your Dark Voice, and it probably doesn't sound even remotely as good.
 
I'm really speechless. You managed to upgrade it while at the same time making it look better. And you seem to have picked the upgrade parts with care, giving more credit to their specifications than to their brands. I'll take your experience as a lesson. I went for brands with my SSMH and the result is not very good. I think the capacitors I used in my power supply have too high ESR. I have 10 420µf of capacitance on the power rails, but I still have a lot of background noise. Makes me sick just to think about it. The problem is that most "boutique" brands don't have those specs in their datasheet. How did you go about selecting the right parts?
 
Another thing I'm curious about, is the enclosure of the Dark Voice a ferrous material? i.e. will a magnet stick to it? I'm asking because my experience with different enclosure material is pushing me to conclude that the only real way to shield an audio circuit is to use a ferrous enclosure, like steel. And something tells me the Dark Force has a steel enclosure.

It's difficult to suggest for sure why you have a noise issue, but ... the proximity of the xfmr to the tubes would be a greater suspicion, IMHO, than the caps.  Still, I'm very sorry to hear it - your SSMH build was outstanding and remains so.
 
Feb 22, 2013 at 3:55 PM Post #100 of 113

WALL-E

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Who's the gentleman in suit? My guess the La Figaro boss himself?
 
Wow! 339 Reference, really nice!!
 
I wish to have the Audio Precision (AP) analyzer even for one day, unfortunately  the kind of measurement apparatus is beyond my reach.
The (Ap) graphs already shows how good the 339 Reference is, really impressive!
The frequency response at low range band is very interesting it's slight boost the upper bass when the load is applied I had similar with my DK339. The mid and high range band is PERFECT -0.4dB on 20kHz! It's probably merit of the new adaptation of input stage (new input tube) may I ask what tubes are they?
The spectrum graph show that mains hum is very low -91bB at 50 Hz almost not audible, THD with the highest 2nd harmonic [dB] -102 and the 3,4,5,6,7,8,9 harmonic below [dB] -110! amazing.
 
I really appreciate it. You put a lot of thought and effort into that mod. Great work!
 
Feb 23, 2013 at 12:38 PM Post #102 of 113

kramer5150

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WOW... impressive!!!
 
What OTs are these?  are they 600:32 ?  Off the shelf or custom winds?  They look like low wattage speaker OTs, 4/8/16 ohms

 
Feb 24, 2013 at 6:14 AM Post #103 of 113

WALL-E

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WOW... impressive!!!
 
What OTs are these?  are they 600:32 ?  Off the shelf or custom winds?  They look like low wattage speaker OTs, 4/8/16 ohms

This amp is OTL construction no "iron" at all.
The picture shows the transformer and two chokes is the parts of  PSU with the JAN 5R4WGB rectifiers.
 
Feb 24, 2013 at 6:28 AM Post #104 of 113

WALL-E

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Was customized to overseas users 93/4

 

I am completely blown away by the look of this amp!! It's High-end Output Transformer less, two-piece design.
 
I followed the creation of this amp quite some time ago on the forum diybuy.net, but I thought that is a only special order, isn't it? You said it “Was customized to overseas users” so this is the standard version of the amp with “premium parts upgrade package” Is that correct? which allows me to wonder, if the "customized platform 9 3/4" was a special order to one of your overseas customer, what about the platform 9 3/4"unmodded" standard version, are you going to produce and sell them like your other La Figaro amplifiers?
 
I would not be able to stretch my budget to include another amp BUT IF how much is it ?
 
thanks
 
Feb 26, 2013 at 9:17 PM Post #105 of 113

xmdkq

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Quote:
 

I am completely blown away by the look of this amp!! It's High-end Output Transformer less, two-piece design.
 
I followed the creation of this amp quite some time ago on the forum diybuy.net, but I thought that is a only special order, isn't it? You said it “Was customized to overseas users” so this is the standard version of the amp with “premium parts upgrade package” Is that correct? which allows me to wonder, if the "customized platform 9 3/4" was a special order to one of your overseas customer, what about the platform 9 3/4"unmodded" standard version, are you going to produce and sell them like your other La Figaro amplifiers?
 
I would not be able to stretch my budget to include another amp BUT IF how much is it ?
 
thanks

 http://www.diybuy.net/thread-461889-1-1.html
 

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