[baronbeehive]

  ..............

My tiny tube amp uses SS very effectively to eliminate the PSU Transformer for a switching one.
It is a huge cost savings.

I still playing around with it to see if I can optimize the somewhat limited PSU.

It is a great conversation piece because it is so dam small a full tube amp:

Edited by Maxx134 - Today at 4:54 am

 
A bit off topic but I remember reading somewhere that the amp was so small it was difficult to keep it from jumping up and down with the music. I think this is where some mods might come in handy, perhaps using my spare Jupiter caps and then extending the bottom.... possibly with some lead shielding to hold it down

!! I think if the makers made it bigger it would be taken more seriously as a proper amp. I would be very interested to hear it with something like the Jupiters, because it is already so good with NOS tubes.
 
I believe the SMPS has advantages and disadvantages: any noise tends to be beyond the range of human hearing - mine has a  very quiet background, but it can be liable to sudden failure with disastrous results.
 
Edit: I have had mine for years with no problems, but my engineer told me about the failure rate so he must have seen examples of this.
 
I have been told that with only 3.5w power output it shouldn't work in my system but obviously the quality of those watts is a major factor.
 

 

[Maxx134]

I have finished upgrading that mini amp,
And suffice to say it is now top notch.

With most tube amps, if there is a signal "coupling" between stages,
You can bet that is going to be the most critical and most obvious upgrade.

I still NOT seeing manufacturers of tube gear acknowledging the usage of highest quality in that area.
They all still using cheapo parts for maximum cost effectiveness.

But if you wanna be the best, you gotta stop being cheap.

While it is great so many cheap amps are affordable,
It is not so often known you can make many a cheap design dam good just upgrading for less than buying a top notch amp.
That's why DIY will always rule as best.

Yet, the expensive tube manufacturers have no excuse going cheap on coupling cap when they command prices beyond $1k.
Some amps use Transformers because of this cap issues.

But today's best caps have come a long way.
So you get a simple amplification design and it can have the edge at purity thru simplicity,
And just need some upgrading.

I also see new designs having great merits with SS helping tubes with CCS, regulation and in PSU.
I have notice tube rectifiers changing outcome of sound before,
Yet I still think it not necessary and SS in PSU can be made better.


Anyways I edited my last post to clarify what was mentioned about paralleled caps..

Cheers

 

[Maxx134]

I been testing some Electrolytic types at the cathode of another amp,
and found these to be superior for a "Cathode bypass" cap:

Audio Note "Kaisei"
So far I believe those are tops for Cathode caps.

*****

I also testing some other caps as coupling.
Although my PIO caps tried sound both lively and musical.
I did notice that both transparency in mids and depth and Soundstage was the determine factor.

The Jupiter copper is still my best choice.
Simply the best cap I ever heard,
although I didn't try expensive Duelunds or Vcaps.

I did try the "Audyn True Copper"...


They are the cheapest copper foil cap I have seen and a true value.
Excellent sound even above mundorf best in natural realistic tonality.
Still waiting to see how it breaks in on Soundstage it almost even so far but it is new.

It give same realism as the other top copper caps,
But just a touch below the Jupiters in depth and holography.
I am expecting it to open up more as they are new and need burn in.
Most caps do need substantial burn in.

 

[SonicTrance]

^^
Nice caps Maxx! It's nice to see your still modding! We're just getting settled after moving house and I'm going to get my workspace setup soon.

 

[Maxx134]

^^
Nice caps Maxx! It's nice to see your still modding! We're just getting settled after moving house and I'm going to get my workspace setup soon.

Me too I have moved into new place and setup my new work space too lol!


Check out this nice cabinet I setup all my Electronic parts on top and tools and tubes in bottom tool boxes:

 

[baronbeehive]

^^
Nice caps Maxx! It's nice to see your still modding! We're just getting settled after moving house and I'm going to get my workspace setup soon.

 
Quote:

Me too I have moved into new place and setup my new work space too lol!


Check out this nice cabinet I setup all my Electronic parts on top and tools and tubes in bottom tool boxes:

 
Hey guys...... can I join in on the party...... BTW... I thought of the move first

.
 
Maxx... your workspace looks way too tidy lol!
 
This is mine

 
Better acoustics after my last place but not an ideal room shape.
 
Edit:
Check out that optical illusion with the speakers.
NB. Those speakers are actually the same height and level and the same distance from the camera but the shape of the room looks weird.

 

[Maxx134]

Nice...

 

[baronbeehive]

Sorry to gatecrash your party guys

.
 
I was wondering if  Mogos has also moved?
 
Edit:
I hope someday to have the setup looking more like Maxx's, at present the working area is in another room...... the kitchen in fact!

 

[MrCurwen]

Agreed, this design takes advantage of using an electrolytic for cathode bypass in powertubes section. Pretty standard.

Indeed. My experience has been - and I'm being a bit devilish here - that standard solutions only produce standard sound quality, not exceptional.

Also, fortunately the distortion scenario you describe, is not happening here

It is. Each cap has a falling phase response when you go down in frequency. The smaller cap has a significant phase distortion occuring inside audio range, most probably inside the most easy to hear middle range.

In essence, the smaller cap still discharges and charges in the frequency range where it is "not supposed to", only it does so

1) with a diminished signal (higher impedance, but signal output still there)

2) with a significant phase distortion.

I personally find this effect smears the soundstage a little bit. Not as much as some other things, but with the lower distortion models I built it was noticeable.

AS I also would not recommend to parallel COUPLING CAPS, unless they are exactly the same type/brand/amount.

No, same effect applies to all uses of capacitors. Some applications more than others, but cathode caps most surely.

Yet for most other purposes, especially across an electrolytic,
They are actually improving the Electrolytic performance with an added cap.

Yes, that is true, they improve the output impedance of the cap system, but at the same time that phase distortion applies. In PSU supplies that are behind a regulator this is not an issue, but inside the actual audio circuit it is.

Once again whether or not this is at all audible in a particular circuit depends on the overall circuit. If there are bigger performance bottlenecks, then it will not be audible.

Another curious note about caps,
is that they can have same voltage and capacitance spec, yet still sound different and why we have the links to caps in first page.

First thing I think when reading this: not a very robust design if it's performance is so contingent on small component variations. I don't mean to be impolite about it, just another perspective to be argued (as I have previously; component choise should not be very important).

I bet MrCurwen is familiar with such designs/solutions.

I am indeed familiar with different transformer coupling and hybdrid (SS coupling) topologies. Not sure if exactly those you mean.

It is a great conversation piece because it is so dam small a full tube amp:

That is one pretty little amp! What are the tubes?

 

[MrCurwen]

I have been told that with only 3.5w power output it shouldn't work in my system but obviously the quality of those watts is a major factor.

I'll continue your off-topic a bit!

3.5 W RMS is in INSANE amount of power, depending on topology of course.

The smallest HIFI amp I've built:







Single ended 6S45P -> source follower direct coupled to 6E5P triode strapped. About 0.2 W RMS output power. Meant to be used with speakers.

It has surprisingly good punch. My girlfriend uses it for background listening in her reading room.

 

[MrCurwen]

Your work spaces are so neat and organized. I'm just sad now.

We moved august of last year, and I still haven't got my electronics laboratory set up for actual use. I parsed most of the stuff thru once, put it in boxes in a bit more condensed manner, but... Well, see for yourselves:



The big cardboard box marked FRAGILE contains my CRTs, well padded. Most are very small, two are 18 and 21 cm in screen diameter. All round, radar CRTs.

The blue boxes are full of tubes. The tube boxes on the left are all empty, I collect the ones I like aesthetically.

The empty chassis' are on top of my work table. I was supposed to build two amps during the winter...

The small boxes on the shelf are full of russian caps. There's more underneath, not in picture.



There's the work table. The boxes on it contain tubes.

On the far left, just barely in the picture there are two (the other one is not in the picture) 5 inch radar CRTs in boxes, in a tower.

The boxes that are on the floor contain miscellaneous components.



More boxes full of tubes and misc tools and components.

The cabinet on the left is packed full of unfinished projects.


So, be happy about your work areas. May this serve as a warning for you to not buy more components.

 

[baronbeehive]

I'll continue your off-topic a bit!

3.5 W RMS is in INSANE amount of power, depending on topology of course.

The smallest HIFI amp I've built:







Single ended 6S45P -> source follower direct coupled to 6E5P triode strapped. About 0.2 W RMS output power. Meant to be used with speakers.

It has surprisingly good punch. My girlfriend uses it for background listening in her reading room.

 
I'm aware that all the hype about 100 + watts is balderdash, my friend has a tube speaker amp rated at 8W and I've been regularly deafened by it on half volume or less. The recommended speaker system for my small amp would be around 95db or more that's why I'm surprised it sounds so good on 87db speakers! But I'm amazed that 0.2W works!

 

[Maxx134]

That is one pretty little amp! What are the tubes?

This is the APPJ PA1502A mini tube amp.
Although the audio path implement triode mode class a design, the rest is very smart solid state PSU and other areas in it so it is almost like a hybrid.

It's a "class A" single ended desing,
But using a "switching" power supply,
and tiny surface mount parts by tubes which look like they implementing some type regulation feeding them.
Maybey a CCS circuit.
It also uses two dedicated output Transformers which have many terminals on them when I peaked inside.

Yes those are "Brimar" mini version of 6v6 to match it size.
Surprisingly good!

I have upgraded what I can on this thing but have not touched the PSU as it is a "switching" type and there is no schematic available that I know.

It sounds dam good now too lol.
It was used to test caps.
I tried different types and also test impact on areas.
You were right I noticed sonic thickness with paralleled caps, but only in coupling stage.

In the cathode position I tried a few types.
I have also used a bypass Wich is common to do for the Electrolytic in that position.

I recently found an electrolytic cap that is very good and just recently posted here.
The Audio Note KAISEI Electrolytic Cap.

I do see and agree that use of capacitor or Transformer coupling, will have to rely on the quality and is a cost issue.

Single ended 6S45P -> source follower direct coupled to 6E5P triode strapped.

Wow that looks like a dam nice tube on the data sheets!
Wired triode nice!

I notice you say you use "source follower direct coupled" which is using Solid State device to couple and may consider it a hybrid, or not(!)

That is very smart move to avoid expensive passive coupling of either cap or Transformer, while maintaining any aplification to the tube, and using Solid State job just in in followers and power supply functions.
That's probably the future of optimizing tube gear.
The mini amp I have proved this to me once I removed some limiting areas in the caps.
Yet it still relied heavily on them because of traditional coupling cap design.

 

[Maxx134]

Your work spaces are so neat and organized. I'm just sad now.

We moved august of last year, and I still haven't got my electronics laboratory set up for actual use.
.

Haha we all moved recently.
It not bad cluttered if you know where everything is, and it keeps others away! lol
I whish I had that much space!

 

[MrCurwen]

I'm aware that all the hype about 100 + watts is balderdash, my friend has a tube speaker amp rated at 8W and I've been regularly deafened by it on half volume or less. The recommended speaker system for my small amp would be around 95db or more that's why I'm surprised it sounds so good on 87db speakers! But I'm amazed that 0.2W works!

If you have "normal sensitivity speakers", you only ever use about 0.1 to 0.2 W RMS power 90% of the time. That is true whether your amp has 100 W of reserve power or 0.3 W.

It's all about the transients. More specifically, how your amp deals with them.

In an amp that uses heavy gNFB to achieve linearity or a low enough output impedance to be useful as an amp, you have a situation where the amp's power must accomodate the full extent of the transient peaks.

That is because the loop will destabilize if it clips, causing very nasty audio products to occur at worst for tens of milliseconds after the transient clip.

On the other hand, if the amp is designed in a way that it can instantly recover from clipping transients, the signal following the transient is reproduced correctly.

The human ear cannot detect the transient missing it's top, if the signal right after it resumes fully correctly. I.e. you don't sense the difference between a transient being 10x the base level and 35x the base level.

So if you only need about 0.2 W RMS at most (that's already too loud for me in most situations) then a 0.5W or 1W amp will provide all the volume and dynamics necessary.

I do admit that a 1W RMS amp does sound better than a 0.2 W amp, but by a surprisingly low margin. A 2W amp doesn't sound any better really.

Keep in mind I am all the time talking about amps with first class impeccable transient response here. An amp using even small amount of gNFB or other 'classic' or 'standard' topologies is not going to sound good at 0.2 W RMS.


To bring it back to the amp this thread is about;

The LD is grossly overpowered (in my opinion) to driving most ordinary headphones. This is because it is utilizing solutions that trade power to linearity and better output impedance.

Many ways to achieve different goals.