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Post by Deleted on Feb 22, 2010 11:10:22 GMT
Must... Resist...  Resistance is futile.  Bravo amps, courtesy of the Borg. Ian |
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Post by Deleted on Feb 22, 2010 14:34:14 GMT
It does have a strange allure! That moth to a light bulb syndrome, it's so pretty, I must get closer..........pssssssst  I don't need one, I don't need one, I don't need one, I don't need one, I don't need one, I don't need one........... |
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Post by PinkFloyd on Feb 22, 2010 21:51:28 GMT
Mike If you carefully reread my remarks, you will find that they were tongue in cheek and aimed solely at Ian as payback for his mischievous comments in Saucereful. Why don't you ask Ian how he took the comments ? Alex, My comments weren't directed at you, in particular, they were directed at ALL these people who comment on amps they haven't heard with "it can't be up to much, look at the circuit" type remarks. I know all your stuff is tongue in cheek so no worries man  I have finally got round to housing a PSU in a Hammond "heatsink" enclosure and, no doubt about it, it improves the performance of the Indeed / Bravo by quite some margin. They are VERY nice sounding with stock PSU's but feed them with something a bit better and the sonics become altogther a lot more classier..... all quite subtle but, across the board, very evident.... more control, more clarity, more depth and more space around singers / instruments (easier to follow each individual component of the sound should you wish to do so) very nice!  I stick by what I said last night, there is very little difference between a £50 amp and a £500 amp (just look at the performance a simple CMOY can give) and, most of the time with headphones, "simple" is all that's required to do the job.... you really don't need a headphone amp the size of a microwave oven to drive a pair of standard, efficient headphones. Of course, charging £500 - £5,000 for an amp has to be justified and they wouldn't get away with a simple CMOY in a box (although GRADO pulled it off with the RA1 ) so they start over egging a simple design to make it appear special and, in some cases, actually ruin the original design by throwing handfuls of unnecessary / expensive components into the mix just to put their "original" stamp on it. People who think that these humongous American type wankfests, that contain everything but the kitchen sink, are any better than a well implemented CMOY are mistaken.... sure, all amps have different signatures but no headphone amp will make the headphones disappear and sound like speakers.... they are all limited, to one degree or another, to "driving" a small transducer and "most" capable designs will do this job very well. You can talk "design" all you want, you might favour opamps, you may favour discrete or you may prefer valves.... you can measure till your heart's content but, at the end of the day, most of the amps on the market today do an equally good job of making music.... it just depends on what "flavour" you like..... none of them are wrong and if you prefer a slightly "warmer" tone then a valve amp may do it for you. I like all flavours which is why I keep a good few head-amps on tap (and a few different pairs of 'phones)..... there is no one size fits all amp / headphone and specifications and response curves mean fck' all to your "ears". I could waffle on all night but, basically, if someone likes the sound of an amp / pair of headphones then that's all that matters! I have heard several VERY expensive "wankfest" American style (UBER expensive) amps and, on each occasion, thought to myself "eh? is that it?..... sounds much the same as a bloody CMOY to me" ;D Price should never be an indicator of "performance" and this is one big problem with Hi-Fi snobbery.... people are, wrongly, led to believe that they will reach audio Nirvana if they pay the price..... obviously, this may be true with loudspeakers as the price to build a mama honking pair of folded horns is a lot more than a pair of Senn HD650 (for example)...... with headphone listening, thankfully, "loadsa money" is not what it takes to reach headphone Nirvana and those people who would lead you to believe you have to take out a second mortgage to enjoy headphone listening are talking out of their rectums. Most of them trying to justify their $$$$ wankfest purchases and putting down everything else as "inferior" ;D All bollocks, the Little Indeed / Bravo amps are wonderfully musical amps and I think your ears are already telling you that for yourselves Enjoy the music! Mike. |
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Post by Deleted on Feb 22, 2010 22:31:37 GMT
Mike
At the risk of further alienating our U.S.A. members, that was the feeling I got from much of the stuff promoted in Computer Audiophile. To me it was a little like "Truth, Justice, and the American Way" They rarely featured anything from other parts of the world. Although they have world wide membership, it seems to be heavily into promoting the home grown products, which are usually quite expensive. Yes, I know, recouping R and D costs, economy of scale, and all that. Nevertheless ...
Alex.
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mrarroyo
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Post by mrarroyo on Feb 23, 2010 0:11:37 GMT
Price has nothing to do w/ performance, I have had both inexpensive and expensive that have impressed and disappointed me (respectively). But to say that all expensive amps are not worth it is not right either. What we need to remember is diminishing returns comes in much earlier plus that some of us need to train our ears to hear the nuances and detail that otherwise we miss.
Lastly it is about the system, it should be balanced. Using a $25,000 cd-player with a $50 amp and a $5,000 headphone is crazy (IMO).
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Post by Deleted on Feb 23, 2010 9:12:30 GMT
What I have been telling all along (but nobody cares ?) ;D There is little to NO difference between very expensive and cheap (but well build/designed) counterparts. There are NO to VERY LITTLE measurable differences (except for amplitude) between the input and output signal of a well build/designed SS amp no matter how much they cost. Build a GOOD differential amp and connect between in and output and load the amp with the HP of your choice. Use MUSIC instead of a tone generator and hear or view on a scope the differences between in and output signals. THIS is the ONLY way to do proper measurements. A simple sweep or tones in different aplitude/freq do NOT tell the whole story. Guess what I have at my disposal  There IS a measurable difference between in and output signal of a Bravo/indeed (built a somewhat similar version before I found out certain aspects of the design I did not like). I agree this may SOUND better to a lot of people  ... so for them it IS better because they LIKE it better this way.  I have NOTHING against that... as Mike says it's all about enjoying music and not about wankfests. (love that word... which we Dutch had a similar word for it, rukpartijtje doesn't quite do it justice) Well designed (feedback or multiple tube) amps have less differences between in and output signals than the 'indeed/bravo' designs.  This implies that amplifiers (good SS and Cmoy alike) and 'better' valve amps PERFORM better have more faithfull reproduction NO MATTER HOW you FEEL about it... is an undeniable FACT.  The fact that these indeed/bravo/sija..su things SOUND pleasant is another bowl of wax but for most RG members far more important than the reproduction of the music being as 'faithfull/intended' a system should be as each and everyone prefer themselves . If you prefer to spend a shitload of money and feel good about it and like the sound who cares as long as YOU feel happy about it /hear it and don't just buy it to impress people or just because you have the dough and don't know what to do with it. If you are a starving student you can get an EQUAL amount of satisfaction/joy from a cheap but good music player, $ 50 headamp en $ 20.- set of cans (modified of coarse ) If a $25,000 cd-player with a $50 amp and a $5,000 headphone setup sounds good then it does regardless of the prices paid for the individual items. Hell... it may SOUND even better than when a $10,000 amp is used if you prefer the 'sound/coloration/distortion of this $ 50.- amp. A funny observation b.t.w..... It is stated that cmoy's and expensive setups do not differ by much. YET when a single cable or capacitor or power supply is changed the differences appear to be HUGE improvements .... |
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Spirit
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Post by Spirit on Feb 23, 2010 10:14:31 GMT
It is stated that cmoy's and expensive setups do not differ by much. YET when a single cable or capacitor or power supply is changed the differences appear to be HUGE improvements .... Love it |
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leo
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Post by leo on Feb 23, 2010 16:38:52 GMT
Mike If you carefully reread my remarks, you will find that they were tongue in cheek and aimed solely at Ian as payback for his mischievous comments in Saucereful. Why don't you ask Ian how he took the comments ? Alex, My comments weren't directed at you, in particular, they were directed at ALL these people who comment on amps they haven't heard with "it can't be up to much, look at the circuit" type remarks. I know all your stuff is tongue in cheek so no worries man I Mike. I usually only comment on stuff I've heard, most of the amps on here I've already built/cloned and tried them anyway ;D Still remember converting the Chiara pcb into a Heed circuit just so I could have a listen to it. There is a few things you have a good idea how they sound before building but its not often I comment on that, maybe the odd thing BTW I really hope that new Indeed is just a prototype in the pic, the pcb looks to be that shit SRBP (like bakerlite stuff) which is god awful, hopefully the production units will use fibreglass . Apart from the added relay , extra RCA's, the high wattage resistor and a few other bits is the actual amp circuit the same? I've no idea whats going off with the heatsinks at the back, it looks like the T0-220 devices are screwed onto a metal pillar going into the heatsink so the part of the transistor which gets hot is isolated from the heatsink  maybe just the picture looking weird |
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Post by PinkFloyd on Feb 23, 2010 21:42:39 GMT
Leo...... the indeed model as pictured is the "potato model" (as Peter puts it) the production model will feature top quality fibre glass boards...... I can't comment further on the design as I have promised to keep my gob shut until it is released.
Mike.
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Post by PinkFloyd on Feb 23, 2010 21:43:16 GMT
It is stated that cmoy's and expensive setups do not differ by much. YET when a single cable or capacitor or power supply is changed the differences appear to be HUGE improvements .... Love it Yeh...... that shut me up Frans |
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leo
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Post by leo on Feb 23, 2010 21:57:21 GMT
Leo...... the indeed model as pictured is the "potato model" (as Peter puts it) the production model will feature top quality fibre glass boards...... I can't comment further on the design as I have promised to keep my gob shut until it is released. Mike. Thats good, should be well sweet |
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Post by PinkFloyd on Feb 23, 2010 22:09:53 GMT
A pic of the PSU I put together for the Indeed / Bravo  Housed in a Hammond Heatsink enclosure ( Rapid part number 30-2252 ) it's a no nonsense, simple PSU consisting of LM7824 regulator on one of my simple boards (with the LM7824 strapped direct to the enclosure to dissipate heat)  Add in a 100VA toroidal and that's it! No switches, no LED's, no knobs or fancy buttons..... I did add a 470nF class X2 across the line and 22NF 300V class Y2 caps between L/N and earth but that's as far as I went....... A simple, make it yourself, PSU for about £50 Getting the nut onto the transformer bolt was a bit of a PITA given the enclosure is "closed" and finger access is "tight" but easily doable if you're used to this kind of thing. Sound quality with a simple regulated PSU? More of everything, in particular quieter between passages, wider soundstage (not "headstage"), more space around instruments...... All amps DO sound much the same (as per my previous post) but feed them with a good power supply and the characteristics start to change for the better...... the difference between a good Cmoy and a bad Cmoy is the power supply I think I better retire to a safe distance and dig myself in further Goodnight! |
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Post by Deleted on Feb 24, 2010 6:53:51 GMT
Nicely made Mike ! looks way better than standard SMPS's. I love NON switching power supplies personally, mostly because of it's RF properties and possible problems it might present in audio chains. the noise on the 24Volt line will be noticeable lower with a stabilized analog PSU. Nowadays, for financial reasons, SMPS are applied in almost everything.  The ferrite seems rather pointless because there are NO spurious RF components in a Non SMPS. These things only have a limited effect in the 10MHz - 1GHz range and are mainly used to pass EMC tests when RF levels are slightly too high to pass the test and need some dampening. Ferrites work best with 3 to 5 windings b.t.w. You better not claim that it has an audible effect in a non-SM environment. ;D |
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Post by Deleted on Feb 24, 2010 7:26:27 GMT
3 to 5 turns of enamelled copper wire on a ferrite bead used to be quite common on the Input to RIAA Phono preamps. Ferrite beads + screening is also sometimes of assistance with high Ft devices in CFP VAS and CFP Output stages of amplifiers. I think Mike may be a "belt and braces" kind of guy ?
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Post by Deleted on Feb 24, 2010 7:48:00 GMT
You are correct about the phono stage. The HP wire, however, is not connected to an INPUT. You also should know what it is/was there for. Try to use it without it and you would be receiving LW transmissions on your precious input for the cartridge and input capacitance make a nice LW/MW broadband receiver. The first stage of the amp makes a very nice detector !!! ;D Thats IS the ONLY reason it was there for. sometimes a series resistor of 100 Ohms was/is used to dampen this resonance and is quite effective also.  When used in an output stage it is to prevent oscilations of the endstage when a high capactive load (long cable) is connected. NOT for improving SQ !! |
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Post by Deleted on Feb 24, 2010 7:56:54 GMT
You are correct about the phono stage. This, however is an INPUT. You also should know what it is/was there for. Try to use it without it and you would be receiving LW transmissions on your precious input for the cartridge and input capacitance make a nice LW/MW broadband receiver. The first stage of the amp makes a very nice detector !!! ;D Thats IS the ONLY reason it was there for. sometimes a series resistor of 100 Ohms was/is used to dampen this resonance and is quite effective also. When used in an output stage it is to prevent oscilations of the endstage when a high capactive load (long cable) is connected. NOT for improving SQ !! Frans I am fully aware of all that, and nowhere did I suggest they were used to improve SQ. CFP stages with high Ft output (e.g. Sanken 50MHZ) devices can be sometimes hard to tame, but you ideally need a 100mHZ CRO to diagnose and rectify the problem. Alex |
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Post by MaN227 on Feb 24, 2010 8:12:01 GMT
Leo...... the indeed model as pictured is the "potato model" (as Peter puts it) the production model will feature top quality fibre glass boards...... I can't comment further on the design as I have promised to keep my gob shut until it is released. Mike. dollar to a doughnut its cause of those that rip his/their ideas. Surely, he(Peter) would like to be the first to market with his Indeed designs. miridiy , rightly so , notes the design is Indeed design. Maybe we aren't far from seeing this amps in kit form. like the aune ............ I'm quite pleased with my indeed 6922, and is it just me? I LOVE the led's , it somehow makes it much more interesting to look at on my desk, viewed from the front (as it should be ) the red almost looks like glowing coils more intense than the real glowing bits . maybe its also just me, but I very very much like this Indeed , paired with my cardas cabled hd650. what are the latest thoughts on bias settings? reading of how they can rise makes me wonder . being as it appears fine between 12 and 17v. with 16.5 being optimum, is there (mind u I don't know jack) any harm that can be done as bias rises with play to over 17v ? one last thought I ll throw out. I have thought this tons of times when I look at this amp. I think 1/4 inch glass would be very nice to replace the plexi. (should make it nice weight) And some nice metal posts and caps. I keep seeing knurled ROUND caps and feet(easy to adjust bias and replace) those little nuts current are a major PIA   .... to make it easy to see it n your head the cap same size as the ON/OFF button (on the indeed) is around and half its height, for both top and bottom caps and feet with round .... er posts half the diameter of the caps/feet. my preference would be chrome, Shiny baby or aluminum as the vol knob, stainless? with threads that don't go down too far and using a simple O-ring, u can make short work of checking bias and no fear of breaking your glass. anyway, there you have it, the ramblings of a fool maybe ... but ..... there it is all the same. ;D |
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Post by Deleted on Feb 24, 2010 9:35:46 GMT
What would be a typical resistance setting of the cathode resistor, and the voltage drop across it at optimum bias setting? (after initial setting, and again when hot) A rising Anode voltage reading suggests that the valve is drawing less anode current when hot. Alex P.S. I have forgotten most of what I once knew about valve technology, so don't shoot me ! |
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robertkd
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Post by robertkd on Feb 24, 2010 10:11:42 GMT
What would be a typical resistance setting of the cathode resistor, and the voltage drop across it at optimum bias setting? (after initial setting, and again when hot) A rising Anode voltage reading suggests that the valve is drawing less anode current when hot. Alex P.S. I have forgotten most of what I once knew about valve technology, so don't shoot me ! I think I know this one and as this is for self bias arrangement, look at the anode current verses grid voltage chart draw a line to intercept the grid voltage note the G1 voltage and chose a resistor that will produce that voltage drop with the desired current,... (of course in most low power audio applications there will be no G1 current for a triode) Or for fixed bias , the function of a cathode resistor is slightly different, generally used to provide overload protection via some circuit OR feed back for the bias arrangement |
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Post by Deleted on Feb 24, 2010 10:18:52 GMT
Robert I would expect that the voltage across the cathode resistor is increasing substantially when the valve is hot. What I was thinking of was something like a Zener diode , or other diodes (including LEDs) that had a slightly higher voltage drop than the initial setting, connected across the cathode resistor so that when the voltage rose, they would start to conduct,thus hopefully keeping the anode voltage a little more constant. Probably a stupid idea ? Alex |
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Post by Deleted on Feb 24, 2010 10:27:54 GMT
the used topology of the CCS is highly temperature dependant (therefore when a tube is used also time dependant as the whole assembly/PCB heats up slowly) the current supplied by the CCS is NOT constant over time/temperature (why I used another design for the CCS) Therefore the Anode voltage will CHANGE. Also there is differences in tubes with emission over time/temp. This can also cause a different Anode voltage. Don't worry too much about this. as long as the voltage is somewhere between 13 and 17 volts the dynamic range/output voltage generated will be sufficient for most HP's. the changing of the voltage is a property of the design. Adjust it after an hour or so and live with the fact that when switched on the anode voltage will be lower than when it warms up. If you like to improve the constant voltage bit you will have to redesign the CCS. Another design could mean different sonic properties as there is NO feedback in this design. It is a minimalistic design , far from ideal ... nothing more, nothing less. If you like/prefer the sound then use it. No magic ... just common sense. |
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robertkd
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Post by robertkd on Feb 24, 2010 10:27:56 GMT
Well yes the g1 is tied to ground via a fairly low value R and self bias being what is. I any one actually having this issue?
Also is the constant current source constant?? remember there isn't a lot of Anode to cathode voltage to begin with.
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robertkd
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Post by robertkd on Feb 24, 2010 10:46:54 GMT
Looking at the design being DC coupled and I have to say don't like it, is it too much to ask to put a 1uF Poly in line with the wiper on the pot and a 50K resistor g1 to ground?? Or better still take the supply upto 48V put some decent heatinking, ditch the 317 and use another fet inplace of the 317 as a CC source, you might want to clamp the grid of the top fet with a zener too and that 2n30806 might get a bit warm as well. |
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Post by Deleted on Feb 24, 2010 11:12:08 GMT
That would mean a totally different design . the 50k resistor would load the AC component supplied by the tube too much (more distortion/unlinearities). the anode current is somewhat too low for this idea to succeed with a 50k value. For this reason a MOSFET is used as a source follower. Might work with a 1MOhm resistor though (and 0.1uF cap ?) This still wouldn't solve the DC drift in the anode circuit though. the CCS in the Source circuit of the MOSFET is of no importance in the DC drift as it is a source follower. The big capacitor already takes care of the DC offset/drift not reaching your HP. a CCS without temp dependency in the Anode circuit (real ref voltage and higher resistor voltage) of the current source, will help but you will have to increase the PS voltage too as you suggest to compensate for the loss in output voltage swing. But why change to much to make it technically a more 'sound' design when users love it to death ? Just forget about the (technical) shortcomings of this design and enjoy the music that is amplified/colored with it.. |
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Post by robertkd on Feb 24, 2010 11:50:06 GMT
Umm yes,... just for fun details obviously aren't there,.. feel free to laugh at it at your convenience. BTW what would you expect say a 10 peak signal because that's about .3Amps (10/32)  |
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... so for them it IS better because they LIKE it better this way. 
maybe just the picture looking weird
.... to make it easy to see it n your head the cap same size as the ON/OFF button (on the indeed) is around and half its height, for both top and bottom caps and feet with round .... er posts half the diameter of the caps/feet. my preference would be chrome, Shiny baby