The DIY'rs Cookbook

[johnjen]

So an update…

I have been searching for a matched pair of 16.8 to 17.0Ω resistors, to tweak the output of the parafeed output xfmrs, with no luck, no matter where I looked and no matter who I asked if they could provide any such items of interest.
And 17Ω resistors simply are not made in the first place, so I was hoping that either 16Ω or 18Ω might work if they were over or under value (respectively).
So I have been ordering resistors in batches of various types and values in hopes of lucking out.
And thus far nothing even came close…
Either they were WAY to high or WAY to low, but no mama porridge anywhere in sight.

So I made a pair that are matched to 0.04Ω (16.98Ω & 17.02Ω) by filing a 'notch' into a pair 15.8Ω carbon film 1 watt resistors.
I suppose I could get them even closer but since this is a prototype and not the final build this will be 'good enough'.
hahahahahahahahahaha

Now in reality, neither the headphones, nor the secondaries of the output xfmrs are anywhere near matched this closely, so this is an exercise in the picking of nits.
But I did replace the 3 resistor build I was using to get close (≈17.2Ω) with single resistors which should be a tweak in and of itself.

And notching the resistors is a 'trick' that I had heard about when using carbon composition resistors, to dial them to reach a desired value.
And due to carbon comp resistors susceptibility to their rated Ω rising thru time from moisture absorption, and when coupled with their SQ desirability, other DIY'rs figured out how to 'compensate' for this issue.
And this 'trick' also works with film resistors.

They are settling in quite nicely as I write this post, so another check list item bites the dust…

And the final build design for the BIG 45 amp is down to 2 finalists, both of which are even simpler that my current build (fewer parts and direct coupled etc.).

This is the current build schematic of the analog section.
With only 2 changes, the single cap in the audio path has moved to the 'other side' of the output xfmr, and the addition of 17Ω resistors across the outputs (pins 1-2 and 3-4)

45 amp analog circuit 1:2019.pdf

JJ

 

[johnjen]

Well those who have followed this thread for any length of time have probably figured out by now that 'good enough' usually doesn't last very long…
It's sorta like saying 'soon', which could be minutes to months… hahahahahahaha

Especially since the very next day my shipment of 15Ω 1watt Carbon Comp resistors showed up and the shorter version of the medium to long story is, I now have a set of 16.8Ω ±0.003 CC resistors in place and I'm listening to them 'settle in' even as I type this with just under 30hrs of total 'on' time since they were made back in the 40's-50's-60's.

It's gunna take a while for these 'vintage' resistors to fully blossom and as a contrast, the previous 17.2Ω Carbon Film were initially 'impressive' which could be a sign of the 'Bose Effect', where this impressive effect wears thin and becomes tiresome, so to speak. Testing continues.

But these CC resistors are on a sneaky/stealth approach, where seemingly out of nowhere a nuance just glides right on by, followed by its cousin, just as your attention is raised and gets drawn and focused on this 'new' sonic aspect, much to my delight!

And to be sure these differences are very slight and the final determination may need to made with the final build and not this prototype.
So these experiments are preparatory and give me a better idea of how much change and what kinds of audible differences each approach 'brings to the table'.
And like the output caps, dialing in the amounts of Ω or µf etc. does help me get acquainted with the peak of the range for dialing in these functions.

More as it happens.

JJ

 

[johnjen]

For those who are at least somewhat familiar with 'cooking your cables', you probably also know they need to be 're-cooked' from time to time.
And for me it's like every 6-9 months.
I've stretched it to 1 year but the SQ falls off quite remarkably.
And if I were afflicted with audio nervosa, I'd probably bump it down to 3-6 months, which thankfully, I'm not THAT persnickety.

Even so, after cooking then get'n e'm settled back in, the net improvement can be startling.

So last night I yanked out just 3 cables, a power cable for the JggyB dac and a pair of balanced IC's, and started the re-cook process.
I left the entire system playing after swapping to back up cables, but went to bed.

So when I donned my 800-Jmods tonight I had forgotten just how much change there can be…
I was immediately reminded, as in, why does this sound closed in and 'pinched', and in several ways at that?

Then the cooker caught my eye with it's status lights flashing away…
Oh, yeah… I be cook'n…

It almost sounds like the difference while listening to music from a mono AM table radio vs a decent FM tuner and stereo system.
And no not quite THAT bad, but the SQ shifts remind me of those kinds of sonic impressions.

And I still have 1 more power cable and another pair of balanced IC's to re-cook, at least for the primary system.
The secondary power cables and AES data feed cables should also get de-scramblated as well, but they can be done piece meal as the opportunity arises.

And re-cooking these cables in small batches like this gives me feed back as to which cables benefit the most from getting re-cooked, again.

JJ

 

[johnjen]

So all of the primary cables in my system (power and IC's) have been cooked and are back in the system and are settling in.

I also have replaced the 'last' SMPS in my system, that powered my word clock, with a LPS.

Next up are the secondary cables for the AOIP system (power and data cables), which means I'll run a SPDIF feed instead of AES in my AOIP setup during the cable re-cook.

The SQ has already returned to levels reminiscent of previous re-cook cycles, only at newer, higher SQ peaks than before, due to all of the changes made to the system since then, like the BIG 45 amp and the Gen6 800-Jmods, etc.

When I 1st listened to the system after re-installing the dac power cable and main IC's, the change in SQ was in a word, gratifying.
It was startling what the shift in the acoustic presentation was.
There was more LEDI (Leading Edge Dynamic Impact) everywhere and the bass had its foundation returned.
It now reaches down and once again imparts a degree of visceral impact, that had faded, which is the tell tale sign that I need to re-cook the cables.

But they still need settling in hours before the SQ reaches it's peak.

JJ

 

[johnjen]

So FINALLY the cables have settled in enough to where that enticing and much sought after MatM (Magic in the Mids) has returned, at least enough that it has my head dancing on my shoulders yet again.
But since I'm still shy of that 200+hr time stamp it will continue to morph and shift.

And I’ll reach that 200+hr mark just in time to undergo another major system change as the HP/pre-amp is inbound and due to arrive next week some time.
And this event will also initiate getting 'serious' with the final build process for the BIG 45 amp.

And depending upon on 'other factors afoot' the BIG 45 amp may get 're-purposed' to drive a set of 'efficient' near field speakers while the HP/pre-amp may become the headphone amp of choice.

These choices have to do with a whole bunch of technical design factors that interact with each other such that the 45 amp may be too powerful (at ≈1.5 watts/ch) and the HP/pre-amp will be better suited for the 800's.

But the ultimate arbiter will be the SQ we achieve.

And we are experimenting with a 4" full range driver in a box (12x12x8) with a transmission line, for added bass boost.
Total parts cost ≈ $100/pair.

I heard a Utoob video of these drivers in a 'nice' box and was suitably impressed despite the fact that it was a video, of a pair of speakers, playing in a room, of a bass cello, and it was VERY impressive.

This type of speaker has many benefits, such as NO crossover, which means the speaker driver is direct coupled to the amp.
And this type of setup is (or can be) very efficient as in 1-2 watts is all that is needed, especially in a near field listening setup.

So a 'Class A' SET amp (Single Ended Triode) can be used in a VERY simple overall system design (very few parts in the audio path) from pre-amp all the way thru to the speaker driver.
And this type of simplified design can deliver surprising SQ far beyond what would be considered possible.

JJ

 

[gefski]

So FINALLY the cables have settled in enough to where that enticing and much sought after MatM (Magic in the Mids) has returned, at least enough that it has my head dancing on my shoulders yet again.
But since I'm still shy of that 200+hr time stamp it will continue to morph and shift.

And I’ll reach that 200+hr mark just in time to undergo another major system change as the HP/pre-amp is inbound and due to arrive next week some time.
And this event will also initiate getting 'serious' with the final build process for the BIG 45 amp.

And depending upon on 'other factors afoot' the BIG 45 amp may get 're-purposed' to drive a set of 'efficient' near field speakers while the HP/pre-amp may become the headphone amp of choice.

These choices have to do with a whole bunch of technical design factors that interact with each other such that the 45 amp may be too powerful (at ≈1.5 watts/ch) and the HP/pre-amp will be better suited for the 800's.

But the ultimate arbiter will be the SQ we achieve.

And we are experimenting with a 4" full range driver in a box (12x12x8) with a transmission line, for added bass boost.
Total parts cost ≈ $100/pair.

I heard a Utoob video of these drivers in a 'nice' box and was suitably impressed despite the fact that it was a video, of a pair of speakers, playing in a room, of a bass cello, and it was VERY impressive.

This type of speaker has many benefits, such as NO crossover, which means the speaker driver is direct coupled to the amp.
And this type of setup is (or can be) very efficient as in 1-2 watts is all that is needed, especially in a near field listening setup.

So a 'Class A' SET amp (Single Ended Triode) can be used in a VERY simple overall system design (very few parts in the audio path) from pre-amp all the way thru to the speaker driver.
And this type of simplified design can deliver surprising SQ far beyond what would be considered possible.

JJ

Have fun with the full range single drivers. The few years I spent with my Merrill Zigmahornets (4" driver in an approx. 5" X 5" X 5' (yes 5 feet tall) cabinet) gave me headphone transparency from speakers. Wasn't the best for "big" music, however.

 

[johnjen]

Say there gefski.
Yeah I know what you mean about 'over driving' a set of small drivers, as they can get 'crowded' all to easily especially when pushed to fill a room.
I'm sorta hoping that by just using them in a nearfield setup that I can avoid that 'pinched' kind of SQ, by not needing to drive them all that hard.
Well, except for the bass where I will need to judiciously apply some EQ to see how far I can push the lower freq response.
Hopefully I should be able to reach 'flat' to ≈50Hz, before it falls off the edge of the known universe, but we'll see.

And their design has already changed from a transmission line enclosure to a dbl horn kind of design.
And at last count, their size has more than doubled as well, to 18x24x8.

But all of this is still at the pencil scratchings on bar napkins stage, with horn mathematics rearing it's ugly head.
Can you say differential equations?

Yeah it can make my head hurt just uttering those 2 words, as memories of college math classes surface… hahahahahahahaha

And it looks like my HP/pre-amp will be 'ready' for our next head-fi meet, but I still need to find a suitable dac to drive it, that, or steal a feed from some body else's balanced dac.
And it'll be a good sized pile of gear to setup, what with the HP/pre-amp being in 2 pieces (16x12x5 each) and the isolation transformer(s) (1 or 2) to feed it.

JJ

 

[johnjen]

And now for a sneak peek of this dbl decker HPre-amp.
And I figure it's going to look even better in person.

Here is the bottom half, the PSU.
You can tell 'cause it's got the On/Off switch… hahahahahahahahahahah



Then we have the top end gear, on top of course.
It has all the knobs and input and output connectors,
and tubz, don't forget the 4 tubz.



And no that 3rd knob is not a balance control.
It is the Multi-Function Configuration Setup, Control & Adjustment, Operational Mode Control Switch , the MFSCCAOMCS.
But we'll just call it The Switch because it is, and it's the only one. hahahahahahahahahahahahaha

Together they will sit as a stack that will be ≈ 14" high by 16" x 12" and have 4 tubes rising from the top plate.
Along with a few xfmrs,… I think
I'll know much more in a day or so.

Doncha just love it when a plan comes together?
hahahahahahahahahaha

JJ

 

[johnjen]

So we've been drilling, mounting and soldering etc. on the HPre-amp and it is sounding VERY nice and just needs a few more things dialed in.

We are also rebuilding the BIG 45 amp, but not as the final build, since we are still experimenting with different designs.
It is both simpler and more complex at the same time, but is smaller and more compact as well.

And we found a MAJOR problem with the power delivery at my house, which has been addressed with significant improvements to the SQ of all my audio equipment.
I'll write up what we found in a future post.

More later…

JJ

 

[johnjen]

Update…
We now have a functional HPre-amp, built a separate pre-amp nicknamed the CBB-26, rebuilt the BIG 45 amp into a smaller-ish chassis, and built 2.5 sets of experimental horn speakers.

The overall SQ has not just risen, nor exceeded our wildest expectation, nor merely reached new degrees of inner detail and focus…
No, no, no…

We have managed to attain levels of SQ that rival some of the best we have EVER heard, and the tweaking hasn't EVEN begun yet.
Such as, we still have several filament voltage regulators to install to see what they can contribute, let alone different bias circuits and we're looking at adding a TVC (Transformer Volume Control) in the CBB-26, etc.

The horn speakers were the biggest surprise of all of these.
They are simply unbelievable and fantastic at the same time.

I'll go into more detail about these builds later, after all the dust and smoke and bits of metal shavings, sawdust, bits a stray wires, solder blobs, excess hot glue, and tools are put away and I get a chance to listen to all these builds work together as they were mean to.

And what we have come up with thus far is still in it's infancy, as in, we will explore just how far we can push these designs, just because we can.

JJ

 

[johnjen]

DUALITIES
Analog vs Digital, SE vs Bal, Vinyl vs Tape…

And now another one for the list, HP’s vs Speakers.
Of course this ‘new guy’ isn’t really new at all, as all of these camps each have their share of both pro & opposed sides to these dichotomies.

And until just recently, but only after we were throwing parts around like popcorn on the breeze, was this gap between my speakers and what my 800-Jmods could deliver, so apparent.

And now I have two setups, each with it’s own DSP EQ etc. and they are remarkably similar and completely different all at the same time.

Without stating the obvious TOO much, speakers provide both channels to both ears while headphones don’t.
Also HP’s have their drivers inches away from our ears encased in a ‘carrier assembly’, while speakers operate in a (relatively) free field.

Yet despite these fundamental differences, each acoustical delivery method can deliver captivating and engrossing musical involvement, but from very different directions and end results.

The degree of articulation an acoustic driver generates, falls off with distance, this is a distinct advantage for headphones and the perfect attribute to have for an audio microscope, to be able to delineate as much of the inner details of a musical passage as possible.
HP’s due to their driver to ear distance can excel in this way.

Speakers on the other hand can ‘blend’ the acoustical pressure waves and can do so in ways that ‘paint’ a more wholistic sonic picture, but at the expense of enhanced inner details.
IOW they present more of the whole picture with less of the drill down into it approach, that HP’s can deliver.
And this whole picture includes texture, and spatial cues, and a sense of 3d presence that HP's can have the most difficulty with.

And both my speakers and 800-Jmods are single driver (no crossovers) designs.
But that’s about the end of the similarities.
These speakers use a $10 (on sale) 4” Dynavox driver which has a whizzer cone.
The horn assembly is square starting at 4ロ” and winding up with a 12ロ” opening.

And in this corner we have the 800-Jmods which are my tweaked 800’s which have 56mm drivers (2.2”).

The 800-Jmods have subsonic bass, extended highs and an impressive soundstage, to name a few attributes.

The speakers on the other hand have a compelling midrange with pinpoint ‘Voice’ placement, and a sense of a ’proper’ harmonic relationship with each ‘Voice’.
These are THE best speakers to play Led Zepplin, and the doors, and the Beatles, and many other albums etc, I have ever heard.
And when the new tube preamp and BIG 45 amp hook up with these horns, well the term MitM (Magic in the Mids) gets a major boost and is redefined to a whole nuther level.

Are these speakers perfect?
Uhmmm, no,
they have some ‘short comings’, like nothing much below ≈85Hz, and they have resonance holes and peaks in their frequency response.
And need precise alignment and are still in their infancy in terms of refinement of the overall implementation.

Thankfully DSP EQ can come to the rescue and ‘help’ out, somewhat…
But what they present to my ears is a compliment and a reflection of the type of details and engaging ‘suck you into the music’ involvement that I call SDSG (SuperDuperSuperGlue) but without the glue sticking all my hair together.
Instead this SDSG is sticking me to my seat, where I keep shaking my head in near disbelief, as nuances and elements of the music reveal themselves anew.

This is the similarity between these 2 acoustical delivery methods, they both are engaging, they both create the musical performance in enticing, compelling and involving ways.
And these speakers do so in ways I never thought that small, full range, horn speakers ever could.
Not to mention their ‘unconventional’ design, along with their use of as cheap a regular dynamic 4” full range speaker driver as I have ever seen.
These aspects, together defy conventional ‘wisdom’, and in ways and with results that are rarely encountered.
And these speakers are cheap, as in dirt cheap, as in ≈$40/pair shipping costs included cheap, for the entire build.

And they scale like a mutha.

Right now I’m running them on my Schiit stack, but when the (not quite as) BIG 45 amp gets more dialed in and is driven by the CBB-26 preamp, these speakers up their game to levels of SQ that simply defy any normal explanation.

They don’t conform to usual horn design parameters, and according to the math and theories and materials normally used for horn speakers they should sound worse than the sound you get from the speakers built into a cheap laptop.

But they don’t.
And so I am re-arranging my desktop setup to accommodate their ungainly shape and size and ‘special’ requirements.
As they continue to surprise and reveal more and more from the music I am accustomed to.
All the while garnering ever more disbelief at what I’m hearing from such an unusual assemblage of extraneous bits and bobs.

Meanwhile the 45 amp (now a mere shadow of it’s former self at only 18”w x 15”d x 9.5”h) is undergoing last minute modifications with LD1085 voltage regulators for all 4 of the DHT filaments which now uses two matched pairs of 112A driver tubes and 45 output tubes.


Here is a pic of one of the regulators




And so it goes.

JJ

 

[johnjen]

So the re-build on the BIG 45amp has made some major headway of late.

We changed the driver tubes to 112A DHT single triodes, and have added 4) LD1085 based filament regulators, 2 Constant Current Sources (CCS's), and removed 7 of the giant Temco Caps (there are now only 3 in use).
We also removed the signal input xfrms and the interstage xfrms, one of the power supply chokes and all (4) of the additional filament xfmrs.
Also the entire filament matching and distribution telephone pole has been replaced by the filament regulators

And so with all of that iron removed, you'd think the amp would be much smaller and much more open with more space and fewer parts.

hahahahahahahahahahahahahahahahahahahahahaaaa

Before


During


After


And while the chassis is completely different, and smaller-ish it actually looks more crowded.
The chassis size has changed from 19" x 12+" x 4+" to 18" x 15" x 9" (including the top side output xfmrs, but not the tubes)

And here is the 'glamor' shot, before the glamor gets added, sort of.
See all the lines and circles and such on the front?
Them're where the glamor ingredients get added…

You know, the inputs and outputs and switches and stuff.

And once I get the holes drilled and the I/O all wired up the amp will be ready to fire up, again, only better now that the whole circuit is nailed down, both figuratively and literally.

Prototypes are like that, they are platforms which enable experimentation and the testing of new design combinations.
These in turn help to 'prioritize' those design aspects in terms of the overall SQ.
This in turn tells us what to use and what NOT to use, both in terms of the specific parts and also specific design approaches.

More as the amp enters operational mode.

JJ

 

[johnjen]

So I mentioned the CBB-26 pre-amp in the main Schiit thread and someone asked for pics.

So I took a few and posted this …
https://www.head-fi.org/threads/sch...bable-start-up.701900/page-3174#post-15013113

The sharp eyed among you may notice the 45 amp has changed since my previous post.

JJ

 

[pbui44]

For those who would like to practice soldering by covering up PCB holes on an expensive and still-incomplete coaster:

https://www.schiit.com/products/coaster

 

[johnjen]

So as of this evening I've completed the re-build of prototype #3 of the 45 amp, meaning it's ready for a power on test and evaluation, which will wait till tomorrow.

So here are a few pics just to show how purdy it all is.

The business end with globe tubes from the 30's and 40's


and the innerds




This build will be MUCH easier and faster to dial in and match the filament voltages and B+ voltage and current feeding the tubes than prototype #2.

This ought to be an interesting exploration into SQ and the adaptability of being able to drive both speakers and headphones.

JJ