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Post by PinkFloyd on Jun 28, 2006 15:07:08 GMT
Got a phone call today and the Heed CanAmp is on its way to me for review. I'll be taking under the hood pictures and will share my thoughts on the amp so check back soon, it's on its way
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rickcr42
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Post by rickcr42 on Jun 28, 2006 15:10:53 GMT
Can't wait mikester.Very cool
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Post by PinkFloyd on Jun 28, 2006 18:56:15 GMT
Can't wait mikester.Very cool Yes, I'm looking forward to it and will post here as soon as it arrives (probably this Friday) Mike.
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Post by PinkFloyd on Jun 30, 2006 20:15:30 GMT
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Post by PinkFloyd on Jun 30, 2006 20:39:18 GMT
Under the bonnet. ALPS RK27 10K potentiometer (blue Velvet) 5W 100R Ceramic resistors NE5532 Jamicon General purpose electrolytics (2 x 16V 4700uF) Metalised polyester film caps (look like Arcotronics R82 series) BD139 Transistors Avisor 9V Transformer 1N4002 rectifier diodes Metal film resistors Fibre glass PCB On / Off rocker switch Nickel plated chassis mount headphone socket Gold plated quad PCB mount phono socket Internal fuse and fuseholder Construction Quality = Very good Now off for a listen
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rickcr42
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Post by rickcr42 on Jun 30, 2006 20:50:26 GMT
Looks good,i bet it sounds good too
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Post by PinkFloyd on Jun 30, 2006 21:14:52 GMT
Looks good,i bet it sounds good too Just a bit Rick! The dynamics, the seamless soundstage, the detail retrieval.... just jaw droppingly good at this price point (at any price even). I keep looking around wondering where "that" strange sound is coming from and good god it's part of the music! When I start hearing new things from recordings I know like the back of my hand something special is happening....... I think I'll be up all night with this amp...............
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Post by PinkFloyd on Jun 30, 2006 21:21:55 GMT
BTW Rick, she runs very warm indeed. You couldn't hold your finger on the 5W ceramic resistors for more than a split second. She's not "fry an egg on the lid" hot but reassuringly "warm" to the touch which I like Detail retrieval and three dimensionality is breathtaking, absolutely first class. Will be back after a prolonged listen and report in full. Mike.
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rickcr42
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Post by rickcr42 on Jun 30, 2006 22:23:29 GMT
a lot of what you are hearing is nice signature 5532 sound and a very simple SE Class-A output stage for driving the cans. Many times simple is best and why I always go back to my SE pure Class-A mosfet Follower Amp as my yardstick to measure all other amps with my Grados feeling as simple and cheap as it was to build anything that can not WHIP IT in significant areas is not worth my time. So far that list is a short one that other than my own personal LH-003 and Class-A LT1010 in the TO-220 pack (class A likes to run hot dude ) open loop unity gain buffers has meant high cost. Because my cans need zero help in the voltage gain department I can keep things simple though understanding anything in the 300 ohm and up range DO need voltage gain as well as a current capability large enough not to crap out on dynamics I realise there is a place for combo stages and with that in mind spend most of my time playing with combination stages,mostly PP class A or monolithic buffers run closed loop,and that is the reason I truly feel there is no TRUE universal headphone amp though many good to great "comprimised" amplifiers example : Zero gain means I can use a circuit open loop that with a simple shunt cap across the input resistor (Rin) I can set the stage bandwidth to eliminate Rf interference.If I take the same care with the power supply and power connections to the amp nothing external gets in unless I WANT IT in,as in music signals only so no garbage in,no garbage out. This works fine with my headphones because there is no need for voltage gain from any source I own. Headphones that DO need voltage gain to achieve enough volume for normal listening levels and still have enough headroom left for peak events mean another stage must be added which unless a single valve amp ended amp invariably means with the output of the final section fed back to the inoput stage,a closed loop amplifier. I don't need to get techy on the benefits of a closed loop amp.we all know them mostly,but I will touch on the problems introduced by such a topology from my understanding and experience. First there is the loop itself.Unlike the former open loop stage anything on the output is fed back to the input so that means anything not wanted will also be fed back.That "not wanted includes any potential RFI that once picked up by the headphone cable and appearing at the amps output will now be looped back to the inverting input of the differential inut stage along with the original signal. Why this becomes problematic even though a rare event (we do try for all potentialities yes ? ) is the way negative feedback operates.The reason why we get benfit from feedback is the way common mode signals are eliminated by the subtractive nature of a differential stage.Where we can get into trouble with a feedback amp is when a signal NOT present on the input is fed back and because it has no alter ego is treated as any other signal and amplified as such along with the content you want amplified. So now we have the added complexity of decoupling the output at RF,simple enough and cheap,but that means adding a resistive element in series with the output with the end result of we just reduced our current delivery to load. It may very well only be a tiny amount and many times not audible as such but it is there so if the output current already marginal can be a problem-comrpimise #1 If you buy into the theory that each suceeding stage needs to be faster than the previous one with the power supply needing to be faster still or you introduce slewing distortions it is readily apparent how you can get into trouble with a multistage amp unless you choose your poison. That poison either hard to work with ultra fast parts,possibly problematic loop filters or a combination of the two.Usually it is "fast enough then filter for the rest" but then we get into phase margins,group delay,etc.-comprimise #2 Finally we get to noise levels.EVERY active stage and not a few passive parts add noise.no matter how LITTLE that noise is it will still be there and is additive so each part adds to the sum (including the power supply as if we didn't already have enough problems ).So the more complex a circuit is,the more stages it has,the higher the end result noise levels will be.Likely not noticed with loudspeakers unless they are very high in sensitivty (horns) because room abient noise is normally WAY more than any noise floor of the electronics but with headphones can be a real bitch becausae of the close proximity/shut out the world nature of the drivers.Let us not forget also every single amplifying stage will also amlify any pre-stage noise present and why MC Cartridge pre-preamps so hard to get right.nmo,our gain levels are not that high and no,modern electronic noise levels mostly low but still needs consideration in any design and especially so if the design is tube based-comprimise #3 So that is my theory on why no headphone amp can be designed for ALL possible headphone loads even though most do a great job all things considered. My beleif is Grado lovers would many times be better of with a simple curren pump and zero additional gain because to be honest I have yet to see a source that could not drive them to full volume unassisted as long as you get the current right for driving such a tough load.By having the ability to use open loop circuits the overall topology complexity is nil which means less audible in the signal path,less to get wrong,less that can GO wrong. Having a need for voltage gain means you have to address each area which adds complexity,increases the parts count dramatically,means you need to actually pay attention to all phases of the path be it signal,feedback or power supply,means harder to do and more expensive to build.In short means you actually have to design something to get it right rather than just hang a damn buffer on the output of your source which being so simple would never sell and if it did because there is only so much you can charge for a buufer and still make a profit ;D so what does this have to do with anything ? Beats me dude.I just felt an urge to write something and this is what came out of my head while I was typing
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rickcr42
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Post by rickcr42 on Jun 30, 2006 22:24:36 GMT
single ended class-a again dude.tried to tell you but did you listen ? Nooooooooooooo !
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Post by PinkFloyd on Jun 30, 2006 22:43:31 GMT
single ended class-a again dude.tried to tell you but did you listen ? Nooooooooooooo ! I'm listening right now and............ wowee, I like it
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rickcr42
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Post by rickcr42 on Jun 30, 2006 23:33:04 GMT
I have to say I was being a wise guy with my earlier "looks get I bet it sounds good too " crack but it really does look damn nice in those pics where formerly I thought the amp just so so in the cosmetics.Not bad,nothing special. I also am reminded of ther Euro habit of making headphone amps that are "all out back" being longer in the front to back dimension with the resulting small left to right area allowing side mounting with other gear where as here in the U.S. we do wider-than-deeper mostly with the result that we either need an entire shelf for the amp or it needs to be on top of something else. This wider than deeper chassis making for a lot of panel space that amp malers feel a need to USE because it is there,add features or lettering not needed-clutter-whle the Euro amps maintain a very workman like all business front panel with company name,volume pot and headphone out. more tool than work of art even though not unattractive and my bet is less ego involved since it is more about the electronics under the hood than it is the hood
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Nigel
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Post by Nigel on Jul 1, 2006 11:37:55 GMT
Looks fantastic. I know a few people on the 'flat earth' forum seem to be very impressed with Heed Audio. Are they based in Eastern Europe somewhere?
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rickcr42
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Post by rickcr42 on Jul 1, 2006 14:20:09 GMT
Hungary www.heedaudio.hu/en/prod_el.htmlnice to see amps coming from other than the usual suspects once in a while (U.S.,Orient,UK).Diversity is a good thing as is competition and this one looks to be good competition in the wide open $250-$500 amp market where most of us live
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Post by PinkFloyd on Jul 1, 2006 19:23:54 GMT
Looks fantastic. I know a few people on the 'flat earth' forum seem to be very impressed with Heed Audio. Are they based in Eastern Europe somewhere? As Rick said...... Hungary. I know you'd love this amp Nigel, you'd absolutely LOVE it! You could fry an egg on the enclosure (yes, it's running HOT today) and the sonics will be right up your street.... guaranteed I'll have a word with Alpar and see if I can send the amp back via you Thing is, I think I want to keep it.. no, I "know" I want to keep it...... Mike.
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rickcr42
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Post by rickcr42 on Jul 1, 2006 20:42:06 GMT
Build a dman szekeres amp Mike ! If you like the heed you will like IT just run that bastard way higher and hotter than the article and buffer the mosfet gate so you drive it from a low Z to overcome the gate capacitance (retains a better top end).I use jfets but an opamp is fine too,maybe even at X2 gain (+6dB) hell you could also do one like the Heed which is a damn intelligent layout.Wish I thought of it first ;D taking nothing away from the heed man,just ryting to turn you to the dark side (class-A) as I have been trying to for about five years
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Post by PinkFloyd on Jul 1, 2006 21:00:20 GMT
Build a dman szekeres amp Mike ! I'd never build an amp I can't pronounce BTW, I've got enough to be going on with as it is without building yet another one.. this is only the half of it
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Nigel
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Post by Nigel on Jul 2, 2006 0:56:26 GMT
Up there with the very best then Mike? Especially for the price.
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rickcr42
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Post by rickcr42 on Jul 2, 2006 1:48:06 GMT
I realise you don't do scratch builds mike and that is cool man.guys like me build for the joy of the chase,guys like you relish in finding the hidden gems within the price range of "joe mainstreet" then showing them the light in the : "here is how we correct the limits self imposed by the manufacturer in order for him/her to bring you this amp at a price you can afford without slicing profit margins so low they need to run in the red or asking so much they carve out (gut) the middle level working for a living consumer.It's a good amp but we can make it a great amp for not a lot of pain" cool.I dig where you are coming from. So I will at some point design a pcb for Gregs amp even though my version is a "Szekeres" in name as point of reference only,is a circuit that other than the front end is best mounted on a chassis mounted heat sing with a terminal strip just below for the tie points for the "mosfet to terminal strip" gate resistor,drain bypass caps,source resistor. then I will have to do the pdf "walk through" as if a kit,bag up all the parts then send it on down the line so you can do the "kit" build then after you catch your breath (shock to the system after all ) and get the "heart" of the amp down can proceed with with working your magic to maybe bring it to the next level for cheap though to be honest I have the Class-A single ended mosfet high current voltage follower NAILED so at best no more than an excercise in "do it because I can" I have to admit pcbs look nice and are a real aid to someone who can ot read a schemo and do their own layout,or even better for an assembly line where even somone dead from the neck up can do the "pull R1 from the R1 bin,place R1 in the R1 hole,solder R1 to that spot" All good dude.Different strokes and whatnot.Just seems to be not only overkill but an excuse to profit on something with zero profit potential.Look at tomos amps or my own posts and it is clear the szekeres amp needs no pcb. Awright.got a house full,am half lit and may post something totally stupid (like it would be a new thing ) so gotta get and get back to the party.Not JUST a party but I made a couple of rules 1-BYOB 2-if you have a "to die for" special dish make it and add to the buffet 3-any music you bring has a cutoff date of 1975 no matter how much you love it.We are going for an atmosphere here and anyone that blows it will find out what it felt like to be Typhoid Mary Rick out
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xerxes
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Post by xerxes on Jul 8, 2006 13:24:17 GMT
I'd be interested in building one. Reading your posts I get the impression that you are aiming at creating a very specific sound when you build something. It would be really interesting to hear for myself what you're getting at.
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rickcr42
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Post by rickcr42 on Jul 9, 2006 16:32:28 GMT
yup pretty much have decided long ago to design for a specific end result rather than try and make "universal" audio projects that are no more than comprimses to attempt to forsee any possible end use then design in for instance : I use Grado cans mostly and have NEVER EVER needed more than +6dB Voltage Gain (X2) and even that is overkill many times.That totally relaxes front end requirements from minimal to none but becsause of the low impedance load near loudspeaker territory-32 ohms is way closer to 4/8/16 ohms than it is the typical headphone load of 300 oms which is closer to line level. And that is the rub here.High impedance hadphones need voltage drive into a line level load that can be looked at like driving a 600 ohm balanced in studio gear.Being single ended the "1/2 600 ohm line" becomes 300 ohms so any output stage that can drive a 600 ohm line will drive these headphones on the current side of the equation (which is far lower than for driving the 32 ohm Grado) while also needing Voltage Gain in the +20dB area of the line level gain stage (again using a studio environ-the mixing console output would provide this). So you have either : A-minimal if any voltage gain,large load specific current gain or B-Large amount of voltage gain,minimal current gain akin to 1/2 of a 600 ohm line driver THAT is why you can more often than not use a line stage preamp that can drive a 600 ohm balanced line single ended through a line out/headphones out as a dual purpose line stage/headphone amp but why it is usually a bad choice for low impedance headphones without tossing in some major line attenuation then HOPING the output will drive a lower impedance load without signal losses due to the mismatch.Either you need to rework the coupling at best or add in another stage,a Mini power amp" to drive the harder load. So ALL multi-can headphone amps in my opinion (and it is just that but since it is DIY I can emphasise the "Y" to meet specific needs ) are comprimised simply due to the "we must accomotdate the widest market mentality which usually means "usable for all-optimised for no one because we have no clue what YOU will do" So long winded way of saying yes,I aim for exactly what and where I will be using the device then take it from there.Realising things change/needs change my entire system is modular based with a sophisticated switching matrix so I can punch in whatver I need at that time be it additional gain,current boosters,line drivers,etc from any input to any output. works for me though not exactly plug and play
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Post by jelosno on Jul 10, 2006 11:03:13 GMT
Rick, do you SELL any of your amps actually? I was reading through most of the threads of this forum over the last week and I do really like what I have found here I am in no way a electronic expert but can hold a solder iron the correct way and given a plan what to do can manage most things... or so I guess. So, what's all this text about? Well, simple enough, I am looking for a veeery goood headphone amp for my RS-1 Grado. I do have the RA-1 and ordered, mostly out of curiosity, the HeadFive from Jan Meier. For a 'real' headphone amp I was always looking for a tube/valve type. Maybe because I do like the sound of my loudspeaker setup that runs through a valve amp. My signal source CD player also features some valve/tube preamp thingy in it which I like. That way I came to this forum 'through' rock-grotto and the listed mods for the XCan. Although the HEED infos sound very promising I would be very interested what it sounds like with a Grado on the other end. What I am looking for is a headphone amp with a crisp controlled bass, nice 'warm' but clear mids with lotsa sound stage, clear and airy but not 'rough' treble. I know but I still want all that in one amp. I like the RA-1 with the RS-1 but the bass, although very controlled, is a bit on the very lean side and the trebles are very 'edgy' and on the 'rough' side for my ears. Sorry if I have somewhat hijacked this thread. Feel free to move my post somewhere else. Would be great to hear your thoughts though... Cheers Stefan
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rickcr42
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Post by rickcr42 on Jul 10, 2006 14:22:11 GMT
No.I have not found a way to actually sell an amp and make a profit worth the time and hassle without charging what I beleive to be more than the amps are worth,especially on the cosmetics side of the equation.(I can just imagine the cries of "rip off" when upon opening the amp there sits a simple voltage follower with a beefy power supply that any DIYer could make on their own for less,they think ) The original RS-1 mates well with the Grado cans mostly and is a prime example of the "rip off" sayers when the opamp used was identified as costing little.Not the last word in resolution but being a battery powered amp and using a "voiced for Grado" parts lineup will not embarrass either.The retail price not out of line for an actual product even though not my ideal. The Head five is one I don't know other than to say I am not a big fan of the LM6171 Op-Amp sonic signature mated to Grado cans even though many are plus I again personally find the BUF634 to be "mushy" more than it is dynamic,again a personal taste thing. I find the "Grado Sound" needs amp choices much like horns do in the loudspeaker arena and that is above all a smooth upper end of the spectrum or what some call the grado brightness but I call accurate,lively and detailed will become very tiring to listen to for long periods. You WANT the detail extracted from the recording but that detail can not be peaky so most of what are considered bright (called accurate by some) amps are off the list. I have also found that at MOST a gain of X2 (+6dB) is all that is needed since the cans are so sensitive so the only limitation on drive even from a portable device is current delivery to the low Z load of the Grados which is in fact closer to loadspeaker territory than it is your typical headphone amplifier.Think mini power amp and not headphone amp. Combine the two and you come up with pure Class-A as the ideal in a configuration able to put 100-250 mA across a 32 ohm load which leads to open loop high current voltage followers/buffers as the ideal driver. With tubes that means a simple White Cathode follower,Mu Stage or Cathode follower-in fact a line driver rather than amp,a solid state amp like the Szekeres (optimised for a better top end delivery ) or a straight monolithic buffer run open loop (no front end op-amp) like the Stereophile article "Aunt Corey's Buffered Preamp" (or the similiar one in the headwize library) OR run inside a loop with an opamp set to +6dB gain as in most Line Driver schematics.A few options here are one of the the Walt Jung designs (not the opamp series but his actual line driver designs) or one from the Jensen Transformer schematics library The trick is to get as far into class-A as you can,have good current drive without becoming mushy,avoid bright electronics and keep everything low in voltage gain which is not needed.Sounds simple enough but with most amps designed to operate with softer sounding 300 ohm Sennheisers in mind not as simple as it seems at first look. Some links : headwize.com/projects/showfile.php?file=szeke1_prj.htmheadwize.com/projects/showfile.php?file=pawliw1_prj.htmheadwize.com/projects/showfile.php?file=pellerano_prj.htmwww.stereophile.com/amplificationreviews/54/www.jensen-transformers.com/apps_sc.html (see line out apps) waltjung.org/ED_Archives.htmlwaltjung.org/Classic_Articles.htmlALL great reads if only to get an understanding of what goes on between source and driven load look at the Mapletree Audio Ear+ Kits.For the price of admission hard to beat with Grados www.mapletreeaudio.com/BTW: I use tube amps for my main rig and my system gain stage is a straight +6dB SE Class-A 600 ohm balanced/300 ohm single ended transformer coupled stage. All my sources put out pretty hefty voltages so I find I need no ore than X2 (for anything short of punching in a portable player for which I have a dedicated "front end" stage). After this is a simple JFET/LT1010 Buffer that I use for driving my Allesandro MS-1 headphones (Grado made) which more often than not IS my headphone rig. The trick is to use the LT1010 in the "TO" package so you can run it HOT,that is far into class-A as possible without burning up the chip (single resistor setting) and present the input with a very low impedance while provinding the driving source with an easy load-the reason for the jfet front end. My Grado RS-1s are presently on my Szekeres and have been there for a while now and even though I try out this and that has pretty much been a "unit" for a very long time. you definately have come to the right place for getting the most out of the X-series ! Mike has more content up than any other single human on these products plus he listens without hearing one and going strictly by the content available my inclination would be to say "very good" since the design itself IS a Class-A line driver akin to the Szekeres but using a bipolar transistor as the current pump (an ideal device for current gain BTW while the mosfet is not even though it can sound great IF full class-A ) that describes the classic Grado/amp mismatch.One where an opamp is called "detailed" or "nuetral" when voiced to be used with Senns (like the 6171) which translates to "edgy" when used with Grados and the "lean" bass a lack of current drive which Grados NEED to thrive.Specific to the RA-1/RS-1 matchup it is power supply limitations (the battery) mostly holding back the bass though even here there is only so much clean current you can expect from a single opamp. The strength of the RA-1,the lack of a line operated power supply making for ultra clean power delivery,is also the wekness-lack of ultimate power extension because of the battery. Jumping to the opamp part-no matter how much we would like it to be otherwise there are limits to how much current a small plastic pack opamp can deliver without melting so they all slide to class AB at some point (1-2mA or so,some higher,some lower) or even into full class-B operation which is fine for a high gain amp where only the peaks will be out of Class-A but not so optimal with a low impedance very sensitive headphone where it will ALWAYS be in class-AB or B because of the requirements of the cans ! Something overlooked far too often I think and why single opamp designs mostly fail even though fine for senns. Clean current baby ! All you need if the front end electronics are already clean kind of tough to hijack a thread around this joint since having me here means having the KING of the off topic post in residence cheers, Rickmongo
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Post by jelosno on Jul 10, 2006 15:47:30 GMT
Rick, This is a helluva answer. Takes some time to digest that all As far as my tech knowledge goes I might be able to 'glue' together a Szekeres. The Mapletree EAR+ with HD upgrade is USD 500 in kit form and USD 600 fully done. Might be cheaper to import the kit - me being in South Africa now. Also not sure how often I will need new tubes/valves for that one. I have read - I think it was the long article about the Slee Solo by Mike - that the XCan can eat up some fair amount of tubes. Same with the EAR+? The most comfortable route to go is still to purchase a 'commercial' unit like the HEED or Slee Solo. The HEED looks soooo good. Dammit! I did live 40 mins away from Hungary and never made it 'over' the border... Always took my bike into Slovenia and Italy... What would be your recommendation in the ready-to-use category? Any recommendation for a mod on the HeadFive regarding the LM6171 Op-Amp? As for the RA-1. I think too, that the lack of bass is based on these two tiny batteries. Why don't you copy one of your great Grado-Amp designs and distribute those? Brainwork has already been done. Or is it down to 'it never is really finally done' state of mind? Too many questions. Sorry again Stefan
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rickcr42
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Post by rickcr42 on Jul 10, 2006 18:04:49 GMT
really is a simple build.If you decide to take it on i can provide tips to get it to sound better than the straight build all about the knowing man.I once lived in an area I thought to be a "high quality audio free zone" until I moved then found that I had manufacturers of high end gear withing a five minute drive ! the Heard amp looks to be at first glance a nice match for Grados since it is a discrete high current class-A follower (like the szekeres) mated to an opamp front end, easily changed to whatever gain needs you may have while providing a proper buffer to the follower-also important for most pure voltage followers though I usually go with discrete jfets in what is known as a Borbely Follower Stage.both methods work. Mike AKA Pink Floyd is looking at getting some Grados and has the Heed amp so maybe we wait for the detailed report ? the Mapletree in kit form is a real bargain and I beleive a pretty painless build with good instructions (the manuals wer online at one time but since have been pulled).Tube life is all about where you operate the tube with there always being a tradeoff between ultimate sound and tube life so you try and shoot for the middle mostly-good sonics,good lifetime of the tubes. The front end 5751 should last for years and years with the 12B4 likely due for replacing every two years or so,maybe more,maybe less,but is the tube that will be stressed the most because it will run the hottest being a cathode follower stage,more like a power amp output stage than a preamp gain stage Never heard the actual Ear+ amps but have had an almost identical DIY amp and so I can say it will mate well with the Grados but may lack in ultimate slam as do most triode amps that have transformer coupling.As a whole a very pleasant sound maybe translating to how an EL84 SE speaker amp sounds The Heed amp is an unknown but looks right in both design and price but I would hold off for a report. The Slee amps again are an unknown but again are proper amps in that they use a "proper" front end and a "proper" output stage instead of trying to do it all with a single stage.all reports I have EVER read said top flight sonics.so also a possible I am not a huge fan of so called "op amp rolling" beleiving any design worth a shit has been optimised to the opamp used and Jan Meiere if anything is a stickler for detail so would assume this is the case here (the hye about having the ability to use any opamp that is pin compatible in any design is either just that,hype,or the design was never finished ). you may find the amp fine as is and suited to your taste,i just do not like the LM6171 for ME personally ;D If I DID try to roll in another opamp it would be the AD843 though again,not exactly a great match for the BUF634,no "ying/yang" going on between the two.The ADI chips mate for some reason rather well with Grados and especially so in the lower registers where they get the bass right more often than not.The trick is to pick one with a smooth middle and the 843 has that it is obvious there is enough current delivery from the chip used though never really giving the part much of a chance can not say for sure BUT I have always wondered what hitting it with a proper power supply of say 500m/a per polarity would do to the slam factor has been a topic under discussion between myself and Mike from time to time and may well happen either as a product,just a bare bones "here it is with instructions" pcb or even a Rock Grotto DIY project so any of the above possible..........at some point Working on a "product" that has taken most of my time lately trying to nail down the finals so it is not just suited to my system but more of a universal approach while trying to keep the cost within sane limits (failing miserably on that last part ). totally passive was my first blush but realising this may not do for everyone am trying to addin "optional" modules allowing for a buffered record output,a USB input in place of one line in,a headphone amp card in place of what is presently the front panel monitor output and possible even a line driver stage. Interior room being at a premum external powering is a must and that means $$$$$ so my aim is to have the modules all jack mounted and easily retro-fitted later on,which incidently get the RoHs requirements off my ass as well being a "kit" or "add on" rather than a "product" so the answers is yes/no/maybe/dunno questions are good.How else to pick someone elses brain and weigh what you KNOW with what someone says which when added in combination hopefully lead to an answer you can live with
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