Bravo / Indeed Headphone amplifiers

[Deleted]

Mar 27, 2010 21:40:00 GMT andy said:

Someone say that we will be getting rid of the bloomin' blue led?

thanks goodness!!!

keeps my wife awake when im listening....

quite like peanut butter as well

Try a UV LED (purplish) It could have some interesting effects too, with the way they seem to shimmer.

[Deleted]

Mar 27, 2010 21:43:40 GMT PinkFloyd said:

Mar 27, 2010 21:40:00 GMT andy said:

Someone say that we will be getting rid of the bloomin' blue led?

thanks goodness!!!

keeps my wife awake when im listening....

quite like peanut butter as well

Easy to do Andy.... just remove it and whack a diode in.... a tuppence 'happeny two minute job.... I will show how it is done tomorrow (will take pictures)

Mike.

The trouble with diodes is that they are just one way affairs though.

Ian

[PinkFloyd]

On a serious note and back on topic.... I have been comparing the G1 (Indeed) to the MF V-CAN the last couple of nights. Here we have one technically "perfect" amp and one technically "imperfect" amp so you would assume, from Fran's point of view that the Musical Fidelity V-CAN would sound better?

All depends what you listen to. The V-CAN excels with "electro" and "jazz" but the G1 takes the honours with live recordings, rock and classical....

The V-CAN is "clinical" with more involved types of music (prog rock for example) and you just don't get "involved" in the music.... the G1, with all it's technical faults, delivers the music with "SOUL"..... it has a "HEART"..... the V-CAN is metronomic and precise but doesn't have a heart..... it's like listening to a black and white version of a "colour" concert.

As I say, the V-CAN excels with electro but as soon as "humans" are involved in a recording (real voices etc.) the G1 lets all the emotion through.... no other way of saying it, the G1 has a beating heart and conveys the music to your ears in a "realistic" way.

Think of the G1 as Roger Waters (an ugly bugger) "technically" imperfect as a "rock star" but makes the hairs stand up on the back of your neck with his lyrics and music.

Look at the technically "perfect" V-CAN as a boy band.... nice and fresh, fits the bill as far as brainless "teenage" girls are concerned but sounds like turd....

I'm not saying the V-CAN "sounds like turd" just making the point that the G1 sounds more MUSICAL with certain types of music......

I don't listen with an oscilloscope glued to my forehead (call me a neanderthal cave dweller) but I DO know what makes me feel good "musically"...... the G1 does it for this pair of ears and @ £40 I have NO complaints whatsoever.

Pinkie.

[Deleted]

Mar 27, 2010 22:23:38 GMT PinkFloyd said:

I don't listen with an oscilloscope glued to my forehead (call me a neanderthal cave dweller) but I DO know what makes me feel good "musically"...... the G1 does it for this pair of ears and @ £40 I have NO complaints whatsoever.

Pinkie.

That's the difficult part of measurements. I have no idea what makes them so entertaining to listen to but they sound great to me too.

The Miridiy has had so much use since I got it in comparison to other stuff because it communicates so well. The thing is, what part of the measurement is 'communication'?

I don't really think it's that important if it does the job tbh. It's not up to my V2 though which is more extended both ways and also communicates well.

Ian

[PinkFloyd]

Mar 27, 2010 22:03:52 GMT @iancraig10 said:

The Miridiy sounds absolutely amazing after a couple of bottles.

And THAT is what it's all about Ian.... if it sounds good it IS good...... you have to be relaxed / in the zone to "receive" the vibes..... you will NEVER be able to appreciate the joys music if you spend your life "measuring" equipment.... it just won't happen.

You cannot "make" the zone (ie: by drinking, smoking dope etc) and no equipment can make it for you.... it's all about being in the right frame of mind and you have to be programmed to "receive"..... at times like this a transistor radio will take you to seventh heaven.... it's not the equipment, it's "you" that has to be in the zone.

I could write a book on "being in the zone" and "self tweaking" but I haven't practiced the art, fully, myself yet but will be sure to "publish" if, and when, I find the magic "Nirvana" self tweak that can zone us instantly into that land of magic that is the "all nighter listening session"...... where we hear the true magic of the music and become part of it.

Your environment / mood plays a BIG part on your ability to receive the vibes so start tweaking that.... the beauty of the music will follow

A stressed up mathematician will neverexperience Audio Nirvana but a relaxed road sweeper may well do... it's all about conditioning YOURSELVES, Not the equipment.

Pinkie.

PS: many think Peter Belt a "nutter" but IMO he's right on the money when it comes to conditioning your environment and yourself.

[Deleted]

Best 2 upgrades to ANY audio system.

Clean ears

Any chemically induced relaxation, alcohol being my fave.

Back on the blue LED. I think someone said it's not in the audio path, so why not one of those multi colour efforts.

Come on baby, lets go to the Bravo disco, and no, your arse looks great in that nun outfit

[Deleted]

PS: many think Peter Belt a "nutter" but IMO he's right on the money when it comes to conditioning your environment and yourself.

That's a name from the past. I remember that name from the 70's was it?

You're absolutely right about the conditioning Mike.

I remember that was one argument for vinyl. The act of getting a big piece of plastic out and lowering the stylus gave a sense of 'occasion' which conditioned the mind to listen.

That was a criticism of CD in the 80's.

For myself, another thing that is crucial is being able to finely 'tweak' the volume so that I get the perfect 'concert' type image in my head. That may sound a bit anal but it works. The volume that I tweak to definitely has something to do with presence/tone but also MOOD.

For instance, sometimes I may play Yello at concert level, where I want the sheer impact of deep bass to smack me in the face while at other times, I may want a different perspective and go to the back row, listening for nuances.

I can also listen quite happily to a transistor radio or DAB which is pants as far as quality goes. Again, the volume trick does it for me.

That could be why absolute measurements don't worry me either. If the gear is poor as far as figures go, the volume control and state of mind has a lot to do with it.

I also don't get too tied in with the gear. Moreso the music.

Reading that made absolute sense to me and is a pretty good description of how I listen myself.


BTW - I'd better apologise for my appalling behaviour last night. Bear in mind, I was seeing two screens so for me it was doubly funny. It was also kind of theraputic following the heavy stuff earlier and I feel as though I've risen from the dead. (I have a hangover)

ian

[Deleted]

blue LED off:

just solder a wire across the 2 pins that are connected to the LED in the middle of the Tube socket on the bottom.
You don't have to take the LED out, just short it..

BLUE led on again... just de-solder the piece of wire that 'shorts' the LED and it's on again.

No need to put in a diode.

With the right resistor parallel to it (instead of the wire) you can 'dim' this LED if you like.

[PinkFloyd]

Mar 28, 2010 15:12:25 GMT @solderdude said:

blue LED off:

just solder a wire across the 2 pins that are connected to the LED in the middle of the Tube socket on the bottom.
You don't have to take the LED out, just short it..

BLUE led on again... just de-solder the piece of wire that 'shorts' the LED and it's on again.

No need to put in a diode.

With the right resistor parallel to it (instead of the wire) you can 'dim' this LED if you like.

Frans..... the red LED requires a diode if you are removing it??

[Will]

cheese on toast with strawberry jam on top

OOh nice, I make chedder cheese and jam sandwiches sometimes, very tasty, but they do get comments.

The workingman's Brie and Cranberry and reckon.

[Deleted]

Hi Mike,

You are (almost) right when it is about the RED LED but the question was about the blue one.

The RED LED (if you want it off) needs 3 diodes (not just 1) as a replacement.
The BLUE LED can simply be shorted.

Here is my original explanatory post again (from another thread)

the blue LED is there PURELY for decorative reasons.
If you don't like it and want it off you can just solder a piece of wire over it.
You don't have to take it out... just short it.
You can also replace it with a green, orange, yellow, red, purple or even white LED if you prefer that.
Just make sure it is a high efficiency type.

the red LED has a specific function in this amp and is used to provide a bias voltage for the 2 CCS (constant current sources) in the anode circuits of the tube.

A red LED has a specific voltage drop that is reasonably stable.
The voltage drop is dependent on color and current and will be about 1.8 Volts in this case.
It does vary a bit over the temperature range but the transistors Base-Emitter voltage does too and in the same direction so compensates a bit.
The transistor B-E junction has a voltage drop of about 0.5 to 0.55 Volts for those that are interested.

You can't take the red LED out or replace it with another color LED because each color has a different voltage drop and thus the anode current will vary too (and therefore the anode voltage also) if you would put in another color LED.

You can check if the voltage across the LED is around 1.8 volts (give or take a bit) to see if it is working O.K.

It does not matter how bright this LED lights up because that is also dependent on the efficiency of the LED.
It can do it's work already when it barely lights up.

Hope this clarifies a bit about the red and blue LED and the function of the red LED

If in the unlikely event you want this LED out to (see no reason for it) then I suggest you paint it black or cover it in another way.
You can also replace it by 3 or 4 small signal silicon diodes (1N4148 or 1N914) in series.

B.T.W. Mike ...
I actually had a listen to the G1 today whilst playing with the autobias arrangement.
I even modded it so it reached 70kHz (-0.5 dB) but then it sounds like most other amps..
So 10kHz (-0.5dB) it will have to remain if you want to keep the sonic character.

used a MegaPoop3 (copyright Alex ?) player as a source and modded Creative Aurvana Live! (= Denon D1001) as HP.
I know... below PAR but gives a nice indication.

[andy]

thanks for clarification on the blue led frans, i will deffinately be shorting it out very soon.

I know it has been said that LED's can interfer with the sound quality sometimes, so has this blue led been put in purely for looks and if so what would it do to the overall sound?

Andy

[Deleted]

I know it has been said that LED's can interfer with the sound quality sometimes, so has this blue led been put in purely for looks and if so what would it do to the overall sound?

Andy

? ? ?
The Blue LED is there for purely cosmetic reasons. A LED is just a special type of diode. Any noise coming from a LED circuit is more likely due to radiation of crap from the often long supply leads supplying it.
A typical RED LED is so quiet that it is often used not just as an indicator, but to supply a reference voltage equivalent to using 3 normal signal diodes in series, (in this case 1.8V approx.) it also has a temperature coefficient that tracks the base to emitter voltage of the transistor that it is used with in this case, providing a more stable reference current for the valve.
Frans has already summed this up very nicely.

[oohms]

I decided to change that switch it comes with for a decent toggle switch.. and i also added a series inductor to get rid of some of that PSU switching noise.. and it works pretty well!
I also got a sylvania 5963 off ebay (this is the 12AU7 version) but while it has more bass 'slam', the mids are a bit forward and glary.

I'm tempted to replace the IRF510's for LM317's again.. i really did like that sound ;D

[mrB]

Re: Indeed late 2009 version

Mar 16, 2010 21:13:58 GMT @solderdude said:

The voltage between the adj and out pins MUST be exactly 1.25 Volts.
If this is not the case then probably the voltage drop across the in- and out-put is too low therefore the LM317 is not functioning properly as a current source.


You will need to get the anode voltage up.
You can try lowering the current (8.2 Ohms instead of 7.5) and if that is not enough you can alter the Anode CCS current by exchanging the emitter resistors for slightly smaller values increasing the anode current and thus making the anode voltage higher which in turn makes the voltage drop across the LM317 bigger.

Mar 17, 2010 15:13:29 GMT @solderdude said:

You will have to get the anode voltage somewhat higher.

The LM317 resistors will have to be replaced by the same wattage fixed resistors.
I would not recommend a pot for it.
WW pots sometimes have dead spots.

You can also replace the 3k resistors in the anode CCS circuit for a lower value say 2k7 or even 2k2 to get the anode voltage higher.

Re: Indeed late 2009 version

I appreciate your advice on this, and was ready to go ahead, then I caught the discussion on the crosstalk problem. It is certainly there in my unit, and audible distortion is apparent - kind of scratchy. [ I am currently running the Indeed anode voltages at 13.5V to keep my filament V around 7 ]. However, this distortion has not been noticeable to my ears in the past when listening to music with both channels driven. Perhaps that's because it is so many dB below the main signal, or could it be that when BOTH channels are driven the crosstalk (or at least the distortion) is neutralized? Can you measure that with your equipment?

Regarding your plans to modify Ian's Bravo, I am intrigued and look forward to hearing about the outcome. Then I started thinking that maybe the crosstalk problem could be overcome by disconnecting the filaments from the adj pins of the LM317s and replacing them with 2 separate fixed resistors (if needed for the proper functioning of the LM317s) and then creating a separate power supply for the filaments - hopefully with just a few extra components, maybe another LM317? Then I could apply your advice above to bring the valve and LM317s within their proper operating specs. Do you think that is do-able? easily? But maybe the remaining common components (diodes and resistor) would still cause crosstalk? This angle arose in my mind because I am fond of this little amp, and the particular valve I have in it at the moment.

I much appreciate your technical insights and look forward to your thoughts on this when you find the time.

[Deleted]

There's a bit of confusion as to what the amps are, I think.

The G1 is made by Indeed. (Like the G2)

The Bravo and the Miridy are different amps.

I think the Indeed is slightly better in sound. (It's also a little bit bigger than the Miridiy)

All sound really good.

Ian

[Deleted]

Apr 2, 2010 11:12:24 GMT @iancraig10 said:

There's a bit of confusion as to what the amps are, I think.

The G1 is made by Indeed. (Like the G2)

The Bravo and the Miridy are different amps.

I think the Indeed is slightly better in sound. (It's also a little bit bigger than the Miridiy)

All sound really good.

Apr 2, 2010 11:12:24 GMT @iancraig10 said:

There's a bit of confusion as to what the amps are, I think.

The G1 is made by Indeed. (Like the G2)

The Bravo and the Miridy are different amps.

I think the Indeed is slightly better in sound. (It's also a little bit bigger than the Miridiy)

All sound really good.

Ian

Ian
With the one that Frans is modifying for you, perhaps you should get him to replace the Chinese 317 Voltage Regulator with a higher grade LM317/LT317 ?
I feel sure it will lift veils again, and further improve the top end, and perhaps some instruments or male voices will benefit too ?
Alex

[Deleted]

Apr 2, 2010 11:21:33 GMT @sandyk said:

Apr 2, 2010 11:12:24 GMT @iancraig10 said:

There's a bit of confusion as to what the amps are, I think.

The G1 is made by Indeed. (Like the G2)

The Bravo and the Miridy are different amps.

I think the Indeed is slightly better in sound. (It's also a little bit bigger than the Miridiy)

All sound really good.

Apr 2, 2010 11:12:24 GMT @iancraig10 said:

There's a bit of confusion as to what the amps are, I think.

The G1 is made by Indeed. (Like the G2)

The Bravo and the Miridy are different amps.

I think the Indeed is slightly better in sound. (It's also a little bit bigger than the Miridiy)

All sound really good.

Ian

Ian
With the one that Frans is modifying for you, perhaps you should get him to replace the Chinese 317 Voltage Regulator with a higher grade LM317/LT317 ?
I feel sure it will lift veils again, and further improve the top end, and perhaps some instruments or male voices will benefit too ?
Alex

Yes. I know that Frans has found a way of extending it right up to 70 Khz with a good response but he was very concerned about the original sound being totally obliterated that he felt it best not to do it.

Following that, he was thinking about installing a switch so that it could go between two 'modes' if you like.

What he was talking about doing is quite extensive and will make really interesting reading for the guys who can do this kind of stuff themselves.

It won't be a 'Bravo' but it could well be a better amp. Who knows until it's tried?

Thing is, it's a difficult call - do you retain the Bravo character, warts an' all or change it into a better performing amp?

That's what's got my interest. (Especially since I have the others here in any case so I can easily compare)

I think he's nobbled the crosstalk in any case. (Poor guy, he's being watched on here!!!)

Ian

[mrB]

Apr 2, 2010 11:12:24 GMT @iancraig10 said:

There's a bit of confusion as to what the amps are, I think.

The G1 is made by Indeed. (Like the G2)

The Bravo and the Miridy are different amps.

I think the Indeed is slightly better in sound. (It's also a little bit bigger than the Miridiy)

All sound really good.

Ian

Sorry about that, I was just using the term G1 generically to identify your Bravo as one from their first generation, and to identify my Indeed as being one from their first design.

Actually, I think Bravo call their versions V1 and V2, and Indeed call theirs "old version" and MK2. I'll correct my post.

edit: I have a bit of catching up to do it seems. I just found the Indeed G2 is a new design somewhat different to their first generation "old version" and MK2 version, and for all I know Bravo may have come up with a second generation model to keep in competition with Indeed.

[Deleted]

Some mods suggested for Bravo that I've nicked:

Mods:
------
Replace trimmer pots with higher quality Bourns trimmers
Replace PS cap with Nichicon 10K uF 35v
Replace two small ceramic caps with Wima .22uF film caps
Replace output coupling caps with 1000uF 35v Elna Silmic II
Bypass coupling caps with Wima .22uF film caps
Clean-up and re-flow all solder joints
Re-case amp in a Mac Mini shell
Replace volume pot with small SMD stepped attenuator
Re-place/re-locate DC power Jack
Replace/re-locate power switch
Replace/re-locate inputs / outputs
Add access port with test points on rear of case for easy biasing measurement

May be useful to those in the know?

Ian

[Deleted]

Hi Guys,
I welcome Ian's collection of potential mods - it reminds me of a very effective thread in another place about the collection of mods for Beresford DACs (which I am very glad I took advantage of ). If any solder competent kindly person is thinking of implementing some or all of Ian's collection I would be happy to offer my G2 as the guinea pig and cover the costs involved.
Cheers,
Dave.

[PinkFloyd]

Another "mod" is to replace the IRF630 MOSFET with an IRF510 Mosfet.... say hello to "detail", say hello to "high frequency"..... the IRF510 totally trounces the IRF630 and opens your Bravo / Indeed right up.....

The following applies to the Indeed G2 but is much the same idea for the BRAVO / Indeed G1:

1: Remove the 1000uF cap. Get a pair of pliers and turn the rod that connects both heatsinks together back and forth a couple of times (this loosens the screw that secures the MOSFET to the heatsink) Remove the screw with a small "flat blade" screwdriver (easier to get in than a philips)



2: Desolder the 630 Mosfet using a desolder pump then remove it:



3: Slot in the IRF510, screw it onto the heatsink then solder it (soldering iron temp. high). All you have to do now is replace the 1000uF cap..... repeat for the other side.



Took me 15 minutes to do both MOSFETS.

[Deleted]

Apr 2, 2010 21:13:08 GMT @davek said:

Hi Guys,
I welcome Ian's collection of potential mods - it reminds me of a very effective thread in another place about the collection of mods for Beresford DACs (which I am very glad I took advantage of ). If any solder competent kindly person is thinking of implementing some or all of Ian's collection I would be happy to offer my G2 as the guinea pig and cover the costs involved.
Cheers,
Dave.

It's great isn't it Dave? The differences that you hear is another world as well. That's what makes this the best headphone site on the market! It hasn't outgrown itself and the talent and knowledge is fantastic without that condescending stuff that you see elsewhere.

It also makes me feel a bit useless 'cos I ain't a techy, although when I was younger, I did solder and mess around with pre-designed circuits to the point of making synthesisers!!! However, if I went back to using a soldering iron again now, I'd proabably destroy a few amps on the way!!

That type of experience and knowledge is rare. To be able to extensively revise an amp is a very highly skilled thing to do, because it involves an excellent knowledge of components/electronics as well as a really discerning ear that truly knows a good sound when they hear it. It's easy to just focus on a difference and believe it to be an improvement, when it's just different. However the improvements I've heard leap out by miles and make other stuff that I have sound absolutely crap!!

I'm also being very honest in what I write about the gear I hear. I'm not just hearing differences because I know that it has been modded. It is absolute Day and Night. Almost like the amps have been injected with steroids.

Ian

[oohms]

For anyone curious about the 12AU7 version of the bravo, check out this thread:

rockgrotto.proboards.com/index.cgi?board=m&action=display&thread=5297

[andy]

Well when the bravo first came out i was so into it that i got two!!! so i have one ready for tweeking

So i will try and get the parts in Ian's list and go from there, If anyone can help with some of the caps that would be great, i have a few laying about but not a huge amount of parts!!

I will also be mounting it in a metal case to help with sheilding, replacing the pot with either a blue velvet or a stepper attenuator i have laying about and using high quality jacks and phonos.

I will start by stripping the pcb completely and starting again from scratch.

any other ideas will be greatly appreciated, and if anyone has parts for sale please pm me!!

thanks all