Bravo / Indeed Headphone amplifiers

[robertkd]

yes the anode CC source but it's less then 1mA, not a lot of heat.

Frans wrt to the 317 they tend to want to let the magic smoke out at 37V (ish) so with some 48V on the supply.

[Deleted]

Not laughing... it's a good suggestion.

The anode CCS is temperature dependant because the parts/topology is, not because they heat up from the drawn current but because they heat up from the heat of the valve and more impartant the LM137 and MOSFET that are on the same PCB.

48 Volts would indeed bring out the lovely smell of smoking parts I am all to familiar with ;D

What I like about the Bravo design over this one is the fact that the heater current is in series with the source current of the MOSFET (a brilliant idea :.
If done as you suggest you would have a considerable increase in PS current as the heater will draw current AND the output stage.
The current of the output stage will have to be considerable as well (being a sourcefollower and needs to be able to drive Low impedance HPs as well without any feedback)
The glowing voltage would have to be lowered from 24Volts to 12 or 6.3 meaning a large dissipation of heat.

The diodes I'd replace with voltage references of 1.2 volts and would compensate for the temp dependancy of the transistor by using a mirrored transitor on 'diode' mode.

the emitter follower won't do much as the MOSFET already has a very high input resistance.
It can decouple the higher capacative load the MOSFET presents to the tube but the capacitance of the MOSFET is not of importance in this design as the miller capacitance weighs much heavier in restricting the frequency range of this design.

The output capacitor I don't like at all in the original and this design.
If there is one thing I would not ever want in my signal path it's an electrolite capacitor.

I reckon best leave it as it is ... it works so ...

[robertkd]

Feb 24, 2010 12:10:26 GMT @solderdude said:

I reckon best leave it as it is ... it works so ...

this isn't a mod for the indeed amp, a sort of trow it out there and see where it goes.

Frans Yes I totally hate having heat generating components, the problem with most design's these days although for where most Ausies live compounds this more T amb,..


Sure the CC's are only conceptual

Could still use heater current which if you use the right tube,
Ah Frans the indeed design also does the heater current in serries but in the scheme of thing it's no big deal. simple 6.3V filament transformers,

The output cap your stuck with unless you provide a low Z rail splitter type arrangement, which kinda defeats this topology But hmmm.

emitter follower yeah just a concept!

And speaking of heat this would be great for those cold winters. ;D

The input capacitor is a keeper as a scratchy pot might sound interesting

[Deleted]

O.K. but if it's not a Bravo/Indeed upgrade... then there is no need to discus it in this thread.

Could start another thread where everyone can input their preferences of how to make an easy to build amp amp combine/pick the best of all favorite topologies.

hmmm transformers ... 6.3V AC on heaters... prefer DC on heaters for it's humm reducing properties.

As for heating... we could design a 1000 Watt class A HP amp that puts out only 1 Watt max as to not damage our hearing and dissipate the other 999 Watt .

For Stereo you would end up with a 2kW heater.. hmm nice and warm... in the winter.
During hot summers... grab your Cmoy !

[MaN227]

Feb 24, 2010 13:35:12 GMT @solderdude said:

O.K. but if it's not a Bravo/Indeed upgrade... then there is no need to discus it in this thread.

Could start another thread where everyone can input their preferences of how to make an easy to build amp amp combine/pick the best of all favorite topologies.

Amen to that man.
It seems the discussion was getting deeper, with not a lot of relevance to this thread that is the Indeed/Bravo amps thread.

surely people can find the NEW Thread button. ;D top right of page

on topic or Hi-Jack lets see .....

[Deleted]

This new thread is in:
Set The Controls For The Heart Of The Sun:
Topic: Class A Single Ended, Variation on a Theme

Here you can make your wishes/preferences known for a HP amp.

When there is enough info we'll look and pick out the interesting bits and feedback so possible topologies can be further refined till we reach a 'near perfect' solution that might be satisfactory to lots of people ?

Now lets give this thread back to the indeed bravo fanclub.. indeed.

[PinkFloyd]

Feb 24, 2010 19:35:44 GMT MaN227 said:

Amen to that man.

Word! ;D

God knows what happened there Let's get back to discussing glowing lights, perspex and shiny glittery things

Soooooo Chaz..... you still liking it man?

[PinkFloyd]

Feb 24, 2010 7:26:27 GMT @sandyk said:

I think Mike may be a "belt and braces" kind of guy ?

I also use a bit of superglue "just incase" ;D Seriously tho', I DO find that ferrite clamps around cables (mains or interconnects) can, in some instances, improve the overall focus of sound..... forget the measuring equipment, my ears tell me it's so... call it belt and braces / snake oil if you like but ferrite clamps, IMO, can (and do) work.

An interesting article: www.audiosystemsgroup.com/SAC0305Ferrites.pdf

[PinkFloyd]

By the way..... I have a friend who can "hear" radio signals (SERIOUSLY)...... he has one of those of those radio controlled clocks and can "hear" the update signal coming in Forget all the theory.... in practice some humans are capable of detecting a LOT more than a scope....

;D

[MaN227]

Feb 24, 2010 23:11:49 GMT PinkFloyd said:

Feb 24, 2010 19:35:44 GMT MaN227 said:

Amen to that man.

Word! ;D

God knows what happened there Let's get back to discussing glowing lights, perspex and shiny glittery things

Soooooo Chaz..... you still liking it man?

Yes Sir , as a matter of fact I am, very much so thx for asking

I guess that sums up my level of knowledge . plastic, lights and shiny stuff ;D .... and again I may be crazy, but I NEVER look at the heed as it fills my head with its wonders (or ANY other amp for that matter) , but ...... I look at the indeed a lot therefore my sharing of my observations and ideas.

the proverbial moth to the flame, I suppose I am ;D

As that appears the only way I can "be a part, contribute in some small way"
I never ever ever will claim to know anything except what my ears tell me, my eyes see and my mind and soul feels.

I may as well be reading a formulation of time space travel made possible due to a black hole in some distant galaxy near the Star 9 Udoofus quadrant, trying to decipher all the techno jargon in here at some points.

Oh well, I will enjoy my music all the same, along with posts I can understand

Peace
Chaz

[Deleted]

Last post in this thread... ?

What do the 'LADDY's' think of this Bravo variation.

4 RCA's (2 in and 2 directly coupled through-outs)
6.3 mm output (or 3 with different output Z's ?).
Volume control.
2 heatsinks on the side.
1 tube as a voltage amp (Bravo topology but better CCS) so the typical Bravo 'sound' is there.
an Opamp buffer with or without DC servo feedback.
same class A output stage as Bravo BUT WITH feedback AND without an output capacitor.

Easy/cheap to build.

made so you can roll tubes and IC's easily

24 volt DC supply voltage

selectable OUTPUT impedance (10-56-120 Ohms)

a lesser gain as the original Bravo.

preferably lesser hiss when the vol pot is at zero.

Would anyone be interested ?

If not ... I'm not going to bother to spend time on it.
If there is I will design something and everyone may shoot at it and come up with suggestions about parts used or change in topologies.

Also suggest housing appearance and specify board sizes even.

Interested ? Then go to the Set the controls for the heart thread and spill your beans.


b.t.w. I knew a guy (a fellow repairman that worked at Technics) that claimed he could 'notice' when our test transmitter was on (we used it to broadcast music on the workfloor so everyone was listening to the same).

We 'tested' him a few times but could not back-up his claims.
He did, however, tackle a real strange phenomenon (which turned out to be static discharges because the casing of a cassette deck motor) was not grounded by moving over the mechanisms with his hands..

The guy went in the nuthouse a few years later (REALLY true, not kidding !!) because he heard voices.

About nuthouses.
If the guy has a 77.5 kHz DCF clock it (very likely) it would be strange to hear an update signal.

The update signal actually is an ABSENCE of a signal.
I happen to know how the DCF77 signal looks like because I built a receiver for it in my intern days on the university of Delft.

It consists of a 77.5kHz burst every second except for the 59th.
The first bit/pulse that follows this absence of signal is the '0' second update mark.
The guy that hears it is must be in the nuthouse too by now because he would have heard a tone (of varying length as the 0 and 1 have a varying burst length) every second of the year (except for the last 56th then)
I guess you won't be able to convince ME with that statement as it seems utter bullocks given the way the signal is composed (wiki DCF77 to check my claims !).

Yes.. there is definitely more to life than we 'know'.
In Audio... I doubt it.
(personal opinion ... don't shoot me)
If there is a 'magic/unknown/undefined' signal that is influenced by ferrite it seems to me not only ferrites do that, also purity of copper,silver,mica, housings of IC's ... should I go on.. I can name all existing substances for that matter seem to influence this signal.

Everytime you change 'something' ... the world 'opens up' again, veils are lifted improvements are all over the place ;D

The reason you find these Ferrites on every cable has to do with legislation... they are found on equipment that would put out too much common mode RF signals (Monitors, ext HD's, SMPS e.t.c) without these so manufacturers can comply to rules and be able to sell their shit.

NOTHING more, NOTHING less.

But if it 'works' for you....then it works.

[Deleted]

Feb 25, 2010 0:32:31 GMT PinkFloyd said:

By the way..... I have a friend who can "hear" radio signals (SERIOUSLY)...... ;D

Lucky chap. He's never late then?

I'd like a homing device fitted so that I never get lost. (Like a pigeon) I could always migrate in the winter then!!

One thing I've noticed with the Bravo: it take about an hour to be on form. Mine is fine from the start, then it goes through a phase of noises (like rustling bags) which then disappears and it works really well from then on.

I hope that heat isn't getting to it 'cos it's had a helluva lot of use since I've had it.

Ian

[robertkd]

Watch out there the thread might be drifting off with that hearing strange frequency shyt and stuff, it may be difficult for some to follow where it's going,... or even where it's been.

[mrB]

Feb 24, 2010 12:10:26 GMT @solderdude said:

The output capacitor I don't like at all in the original and this design.
If there is one thing I would not ever want in my signal path it's an electrolite capacitor.

What would you recommend to replace the 1000uF electrolytics that are used in the Indeed amp? I gather there are a number of improvements that can be made to the componentry of this amp, and this seems to be one of them.

[Deleted]

I recommend to leave it as it is.... Why.. ?

Other RG members might advice to put another brand/type in.
An electrolite of this value remains an electrolite of this value if you change it for another one.
You can't take it out of the circuit ... you're stuck with it and have no real alternatives.
If you don't want them in your circuits either then you need another amp.

Doesn't matter anyway as nobody is worried about or seems to hear it... It sounds good so who cares. ;D
I'm just saying I (personally) don't like them in the audiopath mainly because of aging properties and leakage currents not of sonic properties (shame on me, about to be slammed into a corner and beaten to death I presume ).

Electrolites would have much larger effects in the audiochain as in the PS chain yet in the PS chain the differences are found to be considerable when exchanged... go figure

Don't mind me bashing aluminum electrolite capacitors.
they are better than tantalum or solid aluminum in some cases.
They work well in power supplies when bypassed with a small ceramic capacitor (10 nF is optimal though most designers for unknown reasons use 100nF).
Damn about to be burned alive right now for saying ceramic = good ... very un-audiophile

Measurements confirm that Electrolites and ceramic capacitors together provide far better results in maintaining a low resistance in the power supply rail than when other small capacitors are used.
Of course in Audio land everthing is different and other capacitors rule the sound domain.
I don't care...
I guess education in EMC electronics designing is probably worthless as are very expensive spectrum analysers.

It is useless to bypass the 1000uF electrolite in the output circuit with a 100nF or 1uF capacitor as the vast majority of the audio current runs through the 1000uF capacitor.
a 100 nF capacitor will begin to have an effect above 100kHz.
hardly audible (although some will disagree but can't back it up)
I can't hear above 18kHz so don't give a ...

In a powersupply it IS necesary especially when you use high speed opamps.
If you put in the wrong caps or leave them out the whole thing could oscilate at high (inaudible) frequencies and this can/will affect the sound in te audioregion without you knowing this causes the deterioration as you will need pretty good measuring equipment to detect.
When you attach a meter to detect this the oscilations sometimes disappear magically and you won't even know it is there when you take the meter of again.

Hope to have clarified some about electrolytic capacitors and it's problems.

Of coarse ... some RG members will disagree completely and think I am totally nuts.

[Deleted]

Feb 25, 2010 12:58:21 GMT robertkd said:

Watch out there the thread might be drifting off with that hearing strange frequency shyt and stuff, it may be difficult for some to follow where it's going,... or even where it's been.

?

Now I'm lost. What's that about?

Ian

[Deleted]

Feb 25, 2010 12:58:21 GMT robertkd said:

Watch out there the thread might be drifting off with that hearing strange frequency shyt and stuff, it may be difficult for some to follow where it's going,... or even where it's been.

I think the point of the original remark was to try and illustrate the fact that there needs to be a greater correlation between how something measures, and how something sounds in practice. EEs in general appear to have closed minds to anything but what they have been taught.
To be completely dismissive of what somebody hears just because it doesn't tie in with your University training,update courses, or own personal experience is arrogant.
Thank God for EEs like Bob Pease, who have researched many subjective reports, and often found measureable reasons why people have reported such things. Another firm believer in his instruments and not his ears, is the English Audio engineer Douglas Self, who has written several amplifier design books that are highly regarded,and in his preface , savagely attacks all subjectivity. However, many people are able to make his designs sound better, WITHOUT degrading the incredibly low distortion figures that he designs for. In some cases, measurements are even further improved over the original. As is quite often, it is the power supply area of an amplifier that appears to be the least well engineered part of many designs. Why should remarks by Mike , Stuart, and others, be completely dismissed out of hand without further investigation ?
Alex


Flame suit is on !

[Deleted]

Perhaps I investigated things/claims already.

Just because I am new to this forum doesn't mean I am a newby in Audio.

Alex KNOWS what I already investigated b.t.w.
He also KNOWS I was a 'believer' for quite some time before I discovered how to REALLY measure and use sophisticated measuring equipment and rule certain aspects out.
Based on EARS (mine still work fine) and Brains (think about and deduct) and measuring equipment, access to parts and high-end equipment and last but not least access to people that claim 'they can'.

Can write a book about it... LOL

I do not ever dismiss things at first glance and DO investigate EVERYTHING.

Who else in this forum has actually performed measurements on the crazy idea of using an LM317 as follower in the Bravo circuit ?

This thread is about spilling CONSTRUCTIVE ideas on this Bravo/Indeed variant not about believers or ignorant skeptic techs.

A cheap and perhaps better amp than the Bravo is the goal that can be assembled by the same people that can assemble a Cmoy and not have a chance to be electrocuted by high voltages but still like 'outdated glowing bottles' because it gives them a pleasant feel when enjoying music.

If there is no interest other than 'mine is better, I know better, there is more to life, etc. then there is no point in pursuing this idea..

CONSTRUCTIVE ideas please no endless discussions on who is right an wrong

flames out ! ;D

[PinkFloyd]

I thought it was quite well known that a ferrite clamp on an interconnect, let's say, can improve / change the SQ? In some instances they can even "strangle" the sound.... it's all about trial and error and, if your ears tell you it sounds right with a ferrite clamp around the cables then you are not wrong.

Just because we can't hear above 18kHz doesn't mean the stuff going on beyond that range doesn't have an impact on the sound.... Just look at all the violence in the inner cities.... I put this down to junk food and all the uber high frequencies that are passing through people's heads..... if people wore a ferrite hat there would be a lot less road rage and needless violence.

To say ferrite clamps have no effect because they operate above a range we can't hear is nonsense IMO.... I know MANY people who have clamped their audio cables and they all report a "difference".... there is an interesting article on this somewhere and I'll do my best to find it.

We are animals, after all, and our hearing may only extend to 18kHz but our "senses" extend a lot further than that..... you ever been sitting there and just "know" your mobile phone is about to ring? I have, many times, and how would you explain this other than our senses picking up on the incoming frequency?

I ALWAYS use ferrites in a power supply... call it "belt and braces", call it "a waste of money".... say what you will..... I think they are beneficial to the SQ.... sure, your "test equipment" won't be able to "measure" a difference but human senses are a lot more accurate at detecting "change" than any electronic instrument.

We all have these advanced senses, we just don't need to use them like we did when we were wild animals beating other animals to death with a club ;D Your blind man "has" to compensate for no vision so his hearing / other senses become a lot more acute.

So, Frans, please don't waffle on about "test instruments" as they are not a human and don't have any senses..... never underestimate the power of the human animal's senses.... if, because of your sedentary lifestyle, they have become dormant then it's time to reactivate them!

When listening to a component change ALWAYS do it in a dark room with your eyes closed..... you want your hearing to be the predominant sense..... no point listening to a cable swap, for example, in a brightly lit room, with the TV on, stuffing a Pizza into your mouth...... blank every other sense out and tune into your hearing.

It takes practice but, when you've got the knack, you can pick up on "changes" to the SQ quite easily..... It's all about conditioning yourself to accept the music and nothing but the music.

Mike.

[Deleted]

I stand corrected.

I must be a dumb ass with horrible hearing and no knowledge of the unexplained ..
Also I must be listening during the day in a noisy environment while vacuum cleaning with TL lights on in a metal workshop.
Unfounded assumptions that I would not have even discovered WHEN and HOW to listen for nuances is PURE speculation and ignorance in my book.
Oh yess my book is only a technical manual.

Sorry to break the shocking news..
I am an audio fanatic with HEART for the cause, a good set of ears AND knowledge of parts, equipment and measurements for over 20 years.

I hope this ends all speculations about motives and ignorance on my part and give me CONSTRUCTIVE input.
That's what the Grotto SHOULD be IMHO

As stated before:

USE this thread for CONSTRUCTIVE ideas on this Bravo variant NOT for pissing on people .. that's easy and SAFE behind a keyboard.

Coming up with GOOD ideas that can be implemented that's where the beauty of forums should lie.

CONSTRUCTIVE !!!!!

Now please all ... end this madness and come with ideas

[PinkFloyd]

Feb 25, 2010 22:30:35 GMT @solderdude said:

I stand corrected.

I must be a dumb ass with horrible hearing and no knowledge of the unexplained ..

Nobody said that.

Also I must be listening during the day in a noisy environment while vacuum cleaning with TL lights on in a metal workshop.

Nobody said that either.

Unfounded assumptions that I would not have even discovered WHEN and HOW to listen for nuances is PURE speculation and ignorance in my book.

Why do you think my post referred to "YOU"? I am not discounting your experience OR your measuring equipment I am simply suggesting there's a LOT more to it than "perfect measurements". I hope you are not insinuating that I am "ignorant" Frans? I have a very open mind and am willing to explore any avenue of audio city..... If I were closed minded / set in my ways (like some self proclaimed "experts") then you could class me as ignorant

Sorry to break the shocking news..
I am an audio fanatic with HEART for the cause, a good set of ears AND knowledge of parts, equipment and measurements for over 20 years.

Aren't we all? What makes you any different from the rest of us? I've been into audio since I was 9 years old (I'm almost 49 now) so what are you saying? You know it all? I hope you are NOT claiming that, I would never dream of claiming that.

I hope this ends all speculations about motives and ignorance on my part and give me CONSTRUCTIVE input.

You are free to post whatever you wish Frans. The fact I gave you a "podium" to express your ideas and opinions (and sell your filters) should hit home that I am not your enemy..... I think I have been more than fair?

That's what the Grotto SHOULD be IMHO

I am as "free and easy" as I can be with this forum Frans and I hope most members would agree that this place is different from the norm with a lack of "Ego's", "arguments", "adverts" and is mostly "self" moderating.

If you think it can be improved then I welcome your input but I do NOT welcome "I know more than you" types who want to dictate their ideas and have them accepted as DE FACTO......

USE this thread for CONSTRUCTIVE ideas on this Bravo variant NOT for pissing on people .. that's easy and SAFE behind a keyboard.

I won't comment on that and will leave it up to YOU to think about what you said there.

Coming up with GOOD ideas that can be implemented that's where the beauty of forums should lie.

I agree. I remember when I was the only member on this forum (talking to myself)...... There are now almost 2,000 members so I'd like to think they were influenced into joining because of a few "good ideas" they saw here.

Frans, this is where I could get really pissed off with you...... this forum didn't materialize out of thin air, it was started by one person, then another joined, and another, and another.....

Forums are not a "right" they are hard work to put together and require input from many people. IIRC you don't even know how to upload a photo to the forum so I excuse your ignorance regarding the "management" of this joint..... trust me though, a forum such as the Grotto is NOT a "given"..... a lot of hard work is required

CONSTRUCTIVE !!!!!

Yes Frans..... I heard you the first time. Can I please upload a picture of my arse to "your" forum?...... oh, wait a minute, you don't have a forum? Tell you what mate, you can run this forum for me.... you KNOW best.....

Now please all ... end this madness and come with ideas

No ideas necessary. The indeed / Bravo amps are providing pleasure to listeners, no need for your input (unless you buy one and listen to it for yourself)

Night night Frans





[/quote]

[Deleted]

Hi Guys, I'm really sorry to see this little spat developing - I've not read it all and I understand little of what I've read but you two guys have got much more in common than you have seperating you, so concentrate on that. I'm sure lots of members don't want this to cause a split of any sort - the forum will be much worse without either one of you - kiss and make up, please, but don't get too close ;D
I'm a refugee from another place where minor spats tend to get out of hand and believe me, nobody gains.
Frans, I haven't yet got my Ideal/Bravo but I intend to as soon as the dust settles here on what each has to offer and when the Ideal 2 comes out, so I for one would be interested in you sprinkling a little of your magic dust on it. If you can make the same sort of improvement on the amp as you've made on the HD681 it's a 'no brainer' for me.
Stay cool, both .
Dave

[Deleted]

Feb 25, 2010 23:54:47 GMT @davek said:

Hi Guys, I'm really sorry to see this little spat developing - I've not read it all and I understand little of what I've read but you two guys have got much more in common than you have seperating you, so concentrate on that. I'm sure lots of members don't want this to cause a split of any sort - the forum will be much worse without either one of you - kiss and make up, please, but don't get too close ;D
I'm a refugee from another place where minor spats tend to get out of hand and believe me, nobody gains.
Frans, I haven't yet got my Ideal/Bravo but I intend to as soon as the dust settles here on what each has to offer and when the Ideal 2 comes out, so I for one would be interested in you sprinkling a little of your magic dust on it. If you can make the same sort of improvement on the amp as you've made on the HD681 it's a 'no brainer' for me.
Stay cool, both .
Dave

Dave
Deeply held convictions about subjectivity vs. objectivity are sure to result in some fireworks, but fireworks flame, then smoke , and die out. Valves vs Solid State , and Vinyl vs. CD are another couple of areas where there will always be deep divisions, but fortunately, most of us are mature enough to calm down again shortly afterwards. It's still all about musical enjoyment !

Alex

[robertkd]

Feb 25, 2010 12:58:21 GMT robertkd said:

Watch out there the thread might be drifting off with that hearing strange frequency shyt and stuff, it may be difficult for some to follow where it's going,... or even where it's been.

Umm nothing to do with subjectivity/objectivity,... It was a tongue in cheek dig, we've already been told off once for thread drifting ;D

[Deleted]

Feb 26, 2010 0:10:16 GMT @sandyk said:

[

Dave
Deeply held convictions about subjectivity vs. objectivity are sure to result in some fireworks, but fireworks flame, then smoke , and die out. Valves vs Solid State , and Vinyl vs. CD are another couple of areas where there will always be deep divisions, but fortunately, most of us are mature enough to calm down again shortly afterwards. It's still all about musical enjoyment !

Alex

Hi Alex,
Yep, I understand all that (not being 'clever'), but to continue your analogy (?) we have a saying, "No smoke without fire" and a fire is what I would like to avoid. I know from experience that in written communications the senders mood/attitude can easily be misunderstood by the receiver, who takes umbrage and responds accordingly, only for the original sender to think he is being undeservedly attacked and responds to that and so it escalates. I'm sure I'm 'preaching to the converted' but I don't want two pillars of our community to begin to regard each other with anything less than mutual respect and affection - I've seen it all before, being a very old man ;D .
So, 'hands across the Channel' you guys, shake hands in cyberspace and kiss and make up.
Dave.

PS Has anyone heard anything about Mick (helliharris)? - it's all gone ominously quiet in that area - does anyone have any news?