The DIY'rs Cookbook
Feb 14, 2019 at 5:32 AM Post #1,381 of 1,959

johnjen

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YES!!!!!
YOU WIN!!!!!…!!!!!!
the internet for a whole day of your choosing.
Be the envy of all your friends and bask in the limelight and notoriety.

And for bonus points, can you tell the audience at home, HOW they adjust the tube bias?

JJ :ksc75smile:
 
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Feb 14, 2019 at 2:32 PM Post #1,382 of 1,959

Muziqboy

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YES!!!!!
YOU WIN!!!!!…!!!!!!
the internet for a whole day of your choosing.
Be the envy of all your friends and bask in the limelight and notoriety.

And for bonus points, can you tell the audience at home, HOW they adjust the tube bias?

JJ :ksc75smile:

It's as simple as turning the bias adjustment screw until you see the tubes perform some fireworks and BLOW UP!
lol :stuck_out_tongue_closed_eyes:
 
Feb 14, 2019 at 2:46 PM Post #1,383 of 1,959

gefski

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image.jpg


For the BIG amp, I thought it would require one of these! :smile_phones:
 
Feb 14, 2019 at 2:47 PM Post #1,384 of 1,959

gefski

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Sorry double post.
 
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Feb 15, 2019 at 4:35 AM Post #1,385 of 1,959

johnjen

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It's as simple as turning the bias adjustment screw until you see the tubes perform some fireworks and BLOW UP!
lol :stuck_out_tongue_closed_eyes:
We are diligently taking steps to avoid that particular scenario and all related incendiary type possibilities…
hahahahahahahahahahaha

But since there are no trim pots, and really no pots anywhere in the entire circuit, the inability to crank it to 11 is built into the amp as a safety feature, probably to keep me from, 'seeing what happens if I do THIS'…
As in no fireballs in the living room, thank you very much…
hahahahahahahahahaha

But those custom tweako parts demonstrate the 'true to form' DIY nature of this BIG 45 amp…
Those re-purposed standoffs, bolts and nuts are slugs, and are sized as AA and 1/2AA batteries so that I can remove a single battery from the 4xAA battery pack holders, and thus very easily lower the bias voltage.
This allowed me to drop from 6vdc to 4.5vdc and from 54vdc to 48vdc by removing just one AA and one 1/2AA battery from each quad battery pack.
And cost nothing as they all came from my collection of assorted nuts-bolts-screws-washers etc.

The perfect solution to a situation in an amp in development…
hahahahahahahahahahahaha

JJ
 
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Feb 15, 2019 at 4:41 AM Post #1,386 of 1,959

johnjen

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For the BIG amp, I thought it would require one of these! :smile_phones:
Yeah that would be about what we'd require to adjust the 300VDC B+.

The only problem is it might exceed the floors ability to hold it up and so it could fall thru to the crawl space under the house.
hahahahahahahahah.

JJ
 
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Feb 15, 2019 at 6:32 PM Post #1,387 of 1,959

johnjen

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dup
 
Feb 24, 2019 at 5:30 AM Post #1,388 of 1,959

johnjen

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Ok so a status report on the BIG 45 Amp as it sits just out of elbows reach to my right.

I finished tweaking all the bias currents and filament voltages and have accrued ≈ 48hrs and the SQ has taken a "mother may I?", "why yes you can", leap up in REALNESS to say the least.

There are very few observable changes other than a proliferation of quad AA battery packs squeezed in between xfmrs and 'telephone pole' type voltage drop resistorators, all used to independently tweak the bias on each tube so they are matched and running 'close enough' to ideal.
And the 45 filaments are matched to 0.001vac at 2.5vac with a 1.5amp draw from 2 separate supplies.
I was really surprised they just fell into place like that.

And I measured the current draw on the batteries used to 'power' the bias circuit and it measures as 0.00µa when the amp is off,
and skyrockets up to a whopping 0.05µa when the amp is on.
Which means the battery packs will die of old age before they get drained.
Put another way, they will self discharge faster than the power being drawn in the bias circuits.
AND there is the possibility that the circuits (the grid or the cathode) they are 'polarizing' at a set dc battery voltage, will also tend to want to 're-charge' it, at the same time it is being used as a 'constant' voltage source.
Which in turn means, the battery packs get charged and maintained as they are being used.

A nifty trick if ever there was one.

JJ
 
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Feb 25, 2019 at 1:27 AM Post #1,389 of 1,959

Muziqboy

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Good to hear about the progress of your BIG Eye Yourn amp! lol.
Will you be bringing this to the upcoming meet? that's if you will be attending. Would love to hear it.

Anyway, just want to report a tweak and modification project I just finished recently and MAN! what an upgrade in SQ. Talk about REALISM to the MAX!
Been listening to this DAC since acquiring it after the Bottlehead meet last year and I was surprised to hear the SQ compared to my Battle-worn Theta.
And that was with it being powered by it's internal switching ps. So you know, the gears in my head started turning at the thought of what would be the result if I replaced it with an LPS.
This surgery was not as easy like what we did on the RN3 since this thing actually uses both 5vdc and dual polarity +/-18v so the hunt went on to find the lowest noise regulators I can find.
I think you probably know what regs. I used on this. :stuck_out_tongue_winking_eye:
And it can be powered by both an LPS or the Li-ion batteries for a real off-grid powered DAC! I had to deal with thermal shutdowns of the regs. at first go but nothing that a good-ole fashioned cooling fan can't cure.

And I am happy to say that no one that I know of or heard have done this to this DAC so I can claim the bragging rights on this one!
Hint! Hint! see sig. below to see what DAC it is. :L3000:

If I can make it on Sunday, I'll bring this with the rest of the rig. The Theta can rest at home! hahahaha!
 
Feb 25, 2019 at 2:50 AM Post #1,390 of 1,959

johnjen

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Say there Muziqboy.
Ah yes, yet more tweaking the degree of refinement of our PSU's, with 'satisfactory+' results!!!

It can be quite amazing how much the PSU contributes to the overall SQ of the devices they power.
As both you and I have demonstrated to ourselves, repeatedly. hahahahahahahaha

So did you monitor the noise levels as you added stages of regulation?
Ya know for SCIENCE and all?
And to what level of noise have you reached on the +5vdc and ±18vdc rails?
Ya know curiosity and all…

And there is yet another rather 'rare' tweak that can be applied to our dacs that could result in BIGGLEY SQ changes. And it turns out, may in some cases, be 'easy' to implement.
I haven't jumped into this 'new' rabbit hole quite yet, myself, and it will take some sleuthing and experimenting on our part to know how to dial it all in, but it has that DIY'r magnetic attraction and combination of simple to describe, and to visualize, enough so that we can all too easily get sucked into wanting to pull the covers off and start poking around, perhaps even with a hot solder iron in hand.
hahahahahahahahahahahaha

As for hauling this BIG eye-irn amp to the show, um, it would take a van and 2 of us to haul this monstrosity of an amp around, along with it's support entourage of additional hardware and tools, not to mention that this amp wants a 'hot' balanced signal voltage source to feed it (like a Jggy with 4v outputs).

But the HP/pre-amp being built should be much more 'portable', and is designed (at least as one of it's functions) as a meet rig, but alas it won't be ready for this meet.
Hopefully it will be finished and functional for the meets thereafter.

But what I will bring are my gen-6 HD800-JMods, just so I can hear your rig…
hahahahahahahahahahahahahaha

More later

JJ
 
Feb 25, 2019 at 1:35 PM Post #1,391 of 1,959

Muziqboy

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Don't have any measuring equipment for the noise so don't know what the numbers are on the quad stage but I'm pretty sure it's lower than 0.8uv and on the dual polarity, the published noise are 4uv on the positive rail and 16uv on the negative rail, anyway the best measuring equipment I have on hand are my ears as I did hear an improvement for the better compared to the stock SMPS.

Measurements are good to see and all but in the end for me, it is what I hear in the music that really matters.
 
Feb 25, 2019 at 3:57 PM Post #1,392 of 1,959

gefski

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Don't have any measuring equipment for the noise so don't know what the numbers are on the quad stage but I'm pretty sure it's lower than 0.8uv and on the dual polarity, the published noise are 4uv on the positive rail and 16uv on the negative rail, anyway the best measuring equipment I have on hand are my ears as I did hear an improvement for the better compared to the stock SMPS.

Measurements are good to see and all but in the end for me, it is what I hear in the music that really matters.

So still delivering files via Dante/AES? Anxious to listen!
 
Feb 25, 2019 at 4:38 PM Post #1,393 of 1,959

Muziqboy

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Yup! Still same Dante set-up and that will never change since there is nothing out there at the moment that can de-throne it.

Only change is the DAC I am using now and to my surprise probably edges the Theta in SQ specially after I tweaked and modified the power supply.
 
Feb 25, 2019 at 11:39 PM Post #1,394 of 1,959

johnjen

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Don't have any measuring equipment for the noise so don't know what the numbers are on the quad stage but I'm pretty sure it's lower than 0.8uv and on the dual polarity, the published noise are 4uv on the positive rail and 16uv on the negative rail, anyway the best measuring equipment I have on hand are my ears as I did hear an improvement for the better compared to the stock SMPS.

Measurements are good to see and all but in the end for me, it is what I hear in the music that really matters.
I understand completely.
And ya know there are lots of DVM's that can measure in dB and our local favorite supplier of DVM's, Fluke, does make some decent 'low cost' units.
Just a thought.

However there is a point of diminishing returns in terms of noise reduction on the power supply rails as the load the power supply is feeding is digital, which means LOTS of noise, as in WAY noisier than would be found if it were an analog load.
I noticed this when I was replacing the smps's on the Mutecs and on my ethernet to optical to ethernet bridge that feeds the digital audio signal from the computer to the RN3.
These digital circuits are really noisy, so much so that they will swamp out the small amount of noise from the regulators, AFTER the regulator has done its job and handed the voltage to the downstream load.
I expected this would be the case and my measurements reflected it.

But like you, I did find that adding a 2nd stage regulator did help the SQ of the device it was applied to, so a 3rd and 4th stage may be overkill in some regards but it should prove useful as a benchmark. :beerchug:

And I get the feeling that this meet will be quite memorable for several reasons.

JJ
 
Mar 2, 2019 at 6:00 AM Post #1,395 of 1,959

johnjen

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So there has been significant forward and sideways progress in our quest for a fully tweaked and dialed in tubification approach.

Namely the BIG 45 amp is still settling in after that initial 40+hr blossom action.
Currently it has ≈ 115hrs since the bias tweaking and is following patterns of break in I have witnessed previously, but with differences.
Specifically the timing issues (when the SQ peaks and dips and holds steady etc) are different, thus the sideways progress.

The forward progress is with the HP/pre-amp.
It has recently reached a state of tweak that has resulted in a MAJOR step up in SQ as a HP amp.
This, as you might imagine, is most welcome news, and there remains much tweaking yet to do, which should raise the bar yet again.

The designs have morphed more times than could be documented, and the end to this stage of development is not yet insight.
As I have put it before, the amp is 'getting out of its own way' more and more with wondrous results.

Which portends that it's SQ will be a 'close match' to the beauty of it's wood work.
We sometimes refer to this HP/pre-amp as a 'mini-me' version of the BIG 45 amp, and right now it appears it has surpassed it's BIG predecessor.

JJ
 

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