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Thread: New power amp

  1. #1
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,643
    I'm Jez.

    Default New power amp

    Just getting "first sound" from a new prototype power amp. About half an hour listening done so far and I'm liking what I hear.
    It's solid state, class A and was designed after a lot of thinking about differences in the way valve and SS power amps function and with an eye on getting more valve like sound. Not in any lush or warm way but more that "presence" and immediacy a good valve amp can give.

    It may or may not end up being a product but it was designed with that as a possible outcome

    It's readily configurable in a wide range of power outputs, degrees of class A bias etc.

  2. #2
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 29,533
    I'm Geoff.

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    That's interesting Jez. Looking forward to seeing that one.
    Mr. Tact!

    Main system: MMs/ADCs/Low output MC's/One rare Japanese SUT/One scarce British phono stage/various tonearms/hefty Japanese DD TT and hefty Japanese BD TT and small British BD TT. 4 CD players/2 jitter buster/2 DACs/Valve buffer. TVC stepped attenuator or valve pre-amp or solid state pre-amp. Current dumping power-amp or either of two Class A SS power-amp or Class A EL34 valve monos or big Japanese (part Class A) integrated. Big dual concentric speakers/Smaller dual concentric speakers/Two way British compacts and full range speakers, amongst others. And too much more to list!

  3. #3
    Join Date: Nov 2015

    Location: Wolverhampton

    Posts: 3,538
    I'm Oliver.

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    Any pics Jez?

    Sent from my EVA-L09 using Tapatalk
    Technics SP10 MK2 > Phonomac AT-1010 tonearm > ZYX R50 Bloom cartridge > Jolida JD9 MKII > Firebottle Monoblocks > Creek OBH-11SE Headphone Amp > IXOS Speaker Cables > Pioneer CS-77A Speakers

  4. #4
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,643
    I'm Jez.

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    Quote Originally Posted by Bigman80 View Post
    Any pics Jez?

    Sent from my EVA-L09 using Tapatalk
    NO! It's a prototype lash up and as always with such things is a circuit board and heatsinks etc laying on the carpet. Also I've kind of learned that no matter how much you explain to people that something is a prototype, designed ONLY to be listened to and not looked at, and that it bears ZERO resemblance to any finished product and probably will at this stage look extremely Heath Robinson and like an explosion in a Maplins.... There's still the ones who feel the need to comment on poor appearance, sharp edges, no on/off switch or LED, wires hanging out all over etc etc etc. Some just don't seem to "get it" that this is a stage most products from any company go through in early development. Personally I have no interest in pics of gear anyway but it seems I'm in a minority here!

    Anyhow to get back to more important aspects, a few more details... It's DC coupled as in actually goes down flat to DC, is flat to beyond 100KHz at the other end, uses lateral MOSFETs in the output stage (expensive but very good and extremely reliable) and can be built as anything from a sub 10WPC amp for use with sensitive speakers and up to 300WPC+ at the other extreme. It can also be built with varying degrees of class A output, the more the better of course but also more expensive...

    I wish I could discuss the meat of the thing, what really makes it different etc, but as with any new product one cannot be giving away "trade secrets"!

    As it goes down all the way to DC I may make a historical nod to the NAD 3020 and label the DC inputs "Lab In" and have a second set of AC coupled inputs... The only difference is a capacitor in line when the AC inputs are in use....

    I may well build a linear regulated supply to power the whole amp.... It's running from my bench power supply at the moment for testing and that is of course a linear regulated supply. Not many amps do this as the circuitry is in effect another amplifier and not cheap! Other units which do use a regulated supply are fairly thin on the ground but include the Naim NAP250 and various other models, Quad 303 and several Radford SS amps such as the SPA50 (there will obviously be others but I can't think of any...) Apart from running the whole thing from really pure DC (you'd be shocked how bad the power in a typical SS amp looks on a scope!!) there are other advantages to a regulated supply such as being able to build over-current protection, DC offset protection, thermal protection and slow start into the power supply

  5. #5
    Join Date: Jan 2009

    Location: Essex

    Posts: 16,340
    I'm openingabottleofwine.

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    Sounds interesting Jez.

    Not sure if such a wide bandwidth is really necessary though: I would prefer to see -3dB points at 5Hz and, say, 50kHz respectively.

    DC output protection is a must however.
    Have you listened to this month's choice in the Album Club?

    Barry

  6. #6
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,643
    I'm Jez.

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    Quote Originally Posted by Barry View Post
    Sounds interesting Jez.

    Not sure if such a wide bandwidth is really necessary though: I would prefer to see -3dB points at 5Hz and, say, 50kHz respectively.

    DC output protection is a must however.
    One can always very easily limit the bandwidth to any degree deemed suitable with simple 1st order filters at the input but adding bandwidth is vastly more tricky!!
    With wide bandwidth goes fast transient response, fast slew rate, low or no TID and generally low distortion at high audio frequencies... all of which are highly desirable of course.

    My biggest problem at the moment is too many ideas and not enough work space! I have enough test gear etc to have two work benches on the go but nowhere near the physical space to do this. The relevance being I can do customer repair work and builds etc... OR R&D into new products etc but not both at the same time... It is so frustrating to have to put aside new prototypes. breadboard constructions etc just when it's going well and you can almost taste that a major breakthrough is very close, but, one must earn a living and all that so often prototypes have to be left unfinished with the risk of never being able to quite go back to where you left off.

  7. #7
    Join Date: Mar 2017

    Location: London N2

    Posts: 380
    I'm Edward.

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    Jez, what is the status of this project please?

    Am possibly interested. SS class a sounds yummy.

    Edward
    Source: Win10 server, Win10 Mini-ITX Renderer running JRiver
    DAC / Preamp: Perreaux DP32
    Amp: Radford Revival STA25, TubeHunter Class D IRS2092
    Speakers:, Kudos Cardea C2, Acoustic Research 8BX (modded)
    Power Conditioner: ISOtek Qube 1kw
    Currently resting: Chevron Paradox NDF16 DAC, Radford Revival Prototype preamp, Paul Baldwin 405C amp, Arcam 290P, Sony TA-VA8ES, PMC LB1 Signature, Micromega MyDac

  8. #8
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,643
    I'm Jez.

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    Quote Originally Posted by Edwardlon View Post
    Jez, what is the status of this project please?

    Am possibly interested. SS class a sounds yummy.

    Edward
    It's in abeyance at the moment. I attempted to raise interest in low power class A SS amps a few times but no interest was forthcoming...

  9. #9
    Join Date: Mar 2017

    Location: London N2

    Posts: 380
    I'm Edward.

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    Quote Originally Posted by Arkless Electronics View Post
    It's in abeyance at the moment. I attempted to raise interest in low power class A SS amps a few times but no interest was forthcoming...
    Oh dear that is a pity. Perhaps my interest will change things?

    50w would be perfect. Or were you thinking of even a lower power?

    I don't mind how the thing looks - if it is in a breadbin I would be fine with that. Hey it is a prototype after all.

    If you wish feel free to take this to PM.

    Also I have a simply brilliant idea as to a regulated PSU.
    Source: Win10 server, Win10 Mini-ITX Renderer running JRiver
    DAC / Preamp: Perreaux DP32
    Amp: Radford Revival STA25, TubeHunter Class D IRS2092
    Speakers:, Kudos Cardea C2, Acoustic Research 8BX (modded)
    Power Conditioner: ISOtek Qube 1kw
    Currently resting: Chevron Paradox NDF16 DAC, Radford Revival Prototype preamp, Paul Baldwin 405C amp, Arcam 290P, Sony TA-VA8ES, PMC LB1 Signature, Micromega MyDac

  10. #10
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,643
    I'm Jez.

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    Quote Originally Posted by Edwardlon View Post
    Oh dear that is a pity. Perhaps my interest will change things?

    50w would be perfect. Or were you thinking of even a lower power?

    I don't mind how the thing looks - if it is in a breadbin I would be fine with that. Hey it is a prototype after all.

    If you wish feel free to take this to PM.

    Also I have a simply brilliant idea as to a regulated PSU.
    50WPC is a huge beast of a class A amp! 10WPC is more like what I had in mind....
    The sky's the limit if one has a fat enough wallet and doesn't want to use anything but the amplifier as winter heating

    People seem to be hugely against fan cooling as well which makes things a lot more expensive for bigger class A amps (not needed for 10-20WPC usually). I don't have an issue with them myself as I have found it easily done to make them so quiet you can't hear them unless within a yard or so of the amp in an otherwise silent room. Without fan cooling the heatsinks need to be up to about 5 - 10 times bigger and they are not cheap! The case then needs to be commensurately larger to accommodate the size and weight of the heatsinks, again not cheap....

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