Post by jon on Dec 5, 2018 20:26:02 GMT 12
Ooh Jon - did you put the AmpCamp Amp together? Not yet... lack of time and a spell of illness has meant I gave done nothing.😥
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Amplifier kits Dec 5, 2018 20:27:18 GMT 12
- Edited Dec 5, 2018 20:27:33 GMT 12 by jon
Post by jon on Dec 5, 2018 20:27:18 GMT 12
As for the FU32, I understand that an 823A is a plugin replacement.
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Pundit
Post by papahemi on Jan 19, 2019 15:53:23 GMT 12
So I purchased a FU32 through aliexpress. It arrived quickly and was well-packaged. Not much to do to get it playing, just mount it in some sort of chassis, supply power, hook up input and speakers and you are good to go... I fashioned a wee cage to keep fingers and dog tongues away from danger. I have had it driving some Akai Jetstreams for outside listening while I barbied - even with the 1v output from the laptop it struggled to fill the neighbourhood with sound. I have had it driving some Coral BX-1101 inside and it performed well. Today I thought that I would drop it into the active system, in place of the AR A-04 which has developed a hiss. At a reasonable listening level the bass was overpowering from the subs, I had not yet re-adjusted the levels on the MiniDSP as I wanted to make a direct comparison. Foolishly I the was distracted, eyeing up my Richard Allan CG8t, that have been standing to the side for quite some time, recalling their high efficiency and need for exercise. I swopped out the Corals for the RA, a much better match in efficiency, but still overdone bass - not offensive on JAMC but not right. I was then that I adjusted levels on MiniDSP to equalise the bass - what a dick -cause know I can't be bothered making any other adjustments (too effing hot here), mainly putting the Coral 4A-70 back, readjusting the levels to be able to evaluate just one change. Now I am listening to two changes. Sorry about the crappy pics - i blame the crappy photographer. Anyway as it stands at the moment the wee amp and old Richard Allans are bringing some joy, but lacking a bit of detail. I will give them some time tho, the RA have been sitting around for quite a while and may take a bit of playing to loosen up. The amp itself has only been powered up for less than 10 hrs, so that too may change. All good fun.
We are what we pretend to be, so we must be careful about what we pretend to be.
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Post by Graham on Jan 20, 2019 20:21:36 GMT 12
Excellent work Papa. It looks like a caged animal !
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Post by Owen Y on Jan 21, 2019 8:46:51 GMT 12
That looks like a grunty big tube, 3wpc? I like the 'skyscraper' construction, PSU under, signal board on top.
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Pundit
Post by papahemi on Jan 21, 2019 16:35:32 GMT 12
Yup, lots of surface mount components - not easily modded, but I am quite happy with it at the mo...
We are what we pretend to be, so we must be careful about what we pretend to be.
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Post by Owen Y on Nov 29, 2019 20:31:26 GMT 12
Sun Valley Co. Ltd. is a "100% subsidiary of Toyota Industries Corporation" in Japan. Sun Valley kit amps are being imported into Nth America by VK Music in Canada. Made in Nagoya, Japan. In Mar 2020, the following Phono preamp will be available (in addition to the Line preamp & 211/845 SET amp currently available). SUN VALLEY SV-EQ1616D All Purpose Phono EqualiserCR type phono equalizer ・ Inputs: 2 ・ Output: 1 (STEREO / MONO switchable) ・ Corresponding cartridge: MM (47kΩ), MC (50Ω) ・ MC boost: FET head amplifier ・ Gain: MM36dB ~ 40dB, MC + 25 ~ 32dB (determined by prototype) ・ Vacuum tube: amplification stage: 12AX7 (2), follower stage: 12AX7, 12AU7, 12AT7 can be selected arbitrarily ・ Rectifier: Standard / diode module, option / various rectifiers (5AR4, 274B, 5R4, etc. can be used) ・ Turnover frequency adjustment: Switchable (supports RIAA, EU system SP panel, US system SP panel, AES, NAB, COLUMBIA, etc.) ・ High-frequency roll-off adjustment: ON / OFF selectable (When ON: Continuously variable RIAA and other curves are supported) ・ 115/230v version Pricing (USD excl. shipping): MC/MM phono SV-EQ1616D kit $825 Line preamp SV-Pre1616D kit $785 If you buy both, it is $1,500.00 (Phono EQ1616D kit + Line preamp SV-Pre1616D together) I have built Japanese- made amplifier kits before - the construction & parts quality is solid/robust & instructions clearly illustrated (relying on drawings & diagrams, rather than written language).
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Post by Owen Y on Nov 29, 2019 20:42:38 GMT 12
SUN VALLEY SV-PRE1616D Line Amp - currently available. - 12 AX 7 JJ ECC 82/12 AU 7  - 12 AX 7 GD 12 AU 7 - Mullard CV 4003/12 AU 7 (3 matched) SOVTEK 5 AR 4 You can use the following combination 1) 12 AX 7 - 12 AX 7 - 12 AX 7 (Sharp and high contrast) - Standard combination (SV - 722 Marantz type and same circuit) 2) 12 AX 7 - 12 AX 7 - 12 AU 7 (Skeletal feeling and entity feeling of medium low range) - SV - 722 Mckin type sound image reproduced 3) 12 AU 7 - 12 AU 7 - 12 AU 7 (round and resonate rich) - Featuring a rich overtone feeling of the SV - 310 series Inputs: 4 line [Input 4 can be changed to USB input (option)] Input Volume: Yes frequency response: 15 Hz ~ 70 kHz (-3 dB) gain: 15 dB size: 250W, 225D, 135H (mm ) ※ including protrusions weight: 3.6 kg (Typical instruction pages)
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Post by Owen Y on Nov 30, 2019 15:53:02 GMT 12
A review of the EleKit TU-8600R(Single Ended 300B) amp by STEREOPHILE's Herb Reichert (4 Apr 2019): US$1785 deluxe version with Lundahl transformers & audiophile grade parts. ($1185 for less expensive version with less costly parts.) Cost of selected tubes additional. " The EleKit TU-8600R may look like a generic, old-school, single-ended 300B integrated amplifier, but its sonic character is clean, neutral, and precise in a distinctly 21st-century way. It doesn't sound at all warm or soft, but fast and vigorous, as transparent as any amplifier, and extremely captivating. "
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Post by Owen Y on Dec 11, 2019 16:54:53 GMT 12
HYPEX Class D NC400 amplifier kit: This is a kit version of the well-regarded Dutch HYPEX Class D, NCore amplifier designed to " not just to nudge the best linear amplifiers, but to surpass them in every aspect relevant to sound quality "! Incredibly compact for a 200Wpc amp - but can 'good sound quality' be related to measurable parameters? (My own opinion is the 'voicing' of an audio device is still ultimately dependent on the 'ear' of the designer.) - €575 (excl VAT) per Mono Amplifier complete kit - 140 x 85 x 50(45)mm Mono chassis = Weight 3.1 kg = Power (2Ω)580W, (4Ω)400W, (8Ω)200W, per channel. - " Distortion (THD and IMD) over the full audio and power range is negligible, typically below 0.0007% " - " Overcurrent protection " - " Supply overvoltage/undervoltage protection on all rails " (Mono amp chassis) (Mono Switch Mode PSU module) (Mono Amplifier module)
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Post by Owen Y on Dec 11, 2019 17:02:21 GMT 12
AUDIO ASPPRAISAL build & review of the HYPEX NC400 DIY Class D amp: " Despite their ability to show up just about every flaw in the system or music, however, the Hypex amps are a delight to listen to. " " breakthrough technical performance and stunning sonics, in a package no bigger than a hardback book. " " one of the biggest bargains in high-end audio. "
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Post by colinf on Dec 11, 2019 20:36:21 GMT 12
Class D coming of age? AFAIK they are a discrete circuit. 0.0007% THD out of class D is exteremely low. Wonder what the radio frequency emissions are like? Anyway, they’re a total bargain! Being a very low distortion amp you might want to warm the sound of your system up slightly with a warm sounding preamp.
AMR-iFi R&D
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Pundit
Post by beeman on Jan 4, 2020 14:54:45 GMT 12
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Pundit
Post by simonb on Jan 28, 2020 17:34:49 GMT 12
Ooh Jon - did you put the AmpCamp Amp together? Not yet... lack of time and a spell of illness has meant I gave done nothing.😥 I built a Pass ACA 2 over Christmas and it is awesome into my Fostex based speakers. (A huge step up on the Radford STA25 I have been using) Even in very standard form. I have now made a couple of important mods; -The 'Tungsten' mods to the NFB at the input gives it more organic flow of music and image -I bypassed input and output caps with some Mundorf caps I had here. These took a little time to burn in but a surprising increase in bass extension (given they don't really alter the rolloff point). More musical detail and flow (and tighter bass, now not the slight flab of the standard unit) I plan to get another Meanwell switchmode as a next change (Dual mono and doubling up on capability). Yeah I know it is 'obvious' to go linear... that may come later. Easy is good with this.
Simon Brown Design Build Listen Ltd, Makers of The Wand Analogue Products Distributor of Hana Cartridges
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Post by colinf on Feb 20, 2020 4:28:46 GMT 12
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Post by Owen Y on Feb 20, 2020 10:04:39 GMT 12
The Dutch seem to like toroids. Low radiated flux, compact size, extended HF response,... but not many use them for signal purposes? Pity that Tribute (Pieter Treurniet), also in Holland, has retired from doing audio TXs (not toroids AFAIK).
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Post by colinf on Feb 20, 2020 20:40:25 GMT 12
There just aren’t as many around! Traditional audio transformers with EI cores were invented first, and are easier to manufacture. But there are compelling reasons to use toroidals in audio, as you mention. However they suffer quirks of their own, especially push-pull transformers. The dc bias current in each output valve needs to be matched to within 5% as the risk of magnetic core saturation is greater over that. The frequency response can be double to triple a normal EI output transformer. In a negative feedback circuit that allows much better operation of the feedback loop at high frequencies, resulting in lower distortion and clearer top end.
AMR-iFi R&D
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Post by Owen Y on Nov 9, 2020 9:58:16 GMT 12
I see that Herb Reichert ( STEREOPHILE) has penned a nicely-written & typically interesting review of the SUN VALLEY SV-EQ1616D phono equaliser: This is a Japan-made kit, but is distributed in Nth America by VK Music (Canada) as both a kit & also fully built-up (for an additional US$200(tbc)). (The same guy (Victor Kung) distributes also the Japanese ELEKIT amps.) The SUN VALLEY SV-EQ1616D's phono equaliser, aside from conventional RIAA EQ, offers also: " 78rpm enthusiasts a choice of two filters tailored to match either European or American standard play (SP) recording characteristics. It also has selectable EQ for pre-1956 microgroove pressings from Columbia (NAB) or Philips, Capital, etc. (AES), and it has a boost-or-cut high-frequency adjustment. " - MM Gain is 36dB. - MC Gain +25-32dB is provided by a FET head amplifier with fixed 50-Ohm input loading. - The tube rectifier can be replaced with a Solid State module if you wish (as well as different tube rectifier choices). Herb says: Compared with a US$3000 PARASOUND JC 3+ phono stage: " I gasped playing the first record because the Sunvalley made music feel more intense and exciting than the Parasound, or any other phono pre I have used in the bunker. " " The SV-EQ1616D was giving me expensive, moving-coil–type pleasures...(from a) $755 Ortofon 2M Black moving-magnet cartridge. " With MC cartridges (including the HANA ML, KOETSU Rosewood Signature Platinum, MY SONIC LAB Ultra Eminent & ETSURO Urushi Cobalt Blue) & preferring to use various SUTs, Herb said.... " ... the SV-EQ1616D...generated the most vivid and nuanced analog sound I've had in this apartment. " (Psvane 274B rectifier tube fitted) (Solid State rectifier module fitted)
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Post by colinf on Nov 9, 2020 20:07:34 GMT 12
Very nice. I can vouch for the great sound from the Ortofon 2M Black. As a MM cartridge it doesn’t use an MC stage whether it’s jfet or transformer and is both more transparent and cost effective for it!
AMR-iFi R&D
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Pundit
Post by peter0c on Nov 10, 2020 11:26:45 GMT 12
Let's not forget Transcendent Audio OTL kitsets. www.google.com/search?channel=crow2&client=firefox-b-d&q=transcendent+audio They offer a range of phono, pre and OTL power amps including a 300B OTL. Their main OTLs are based on the Circulatron circuit and they offer some single ended OTLs which are capacitor coupled. I have a pair of Minibeast single ended OTL monoblocks and a grounded grid preamp which didn't break the bank. From the new range 'The Slider' line and phono amp looks particularly interesting. It is possible to buy them in kitset or fully made up but be prepared to wait. The owner Bruce Rosenblit has a good reputation and his book on amp design and building is a good resource. I'd be tempted to say that his kitset amps are close to unbeatable value for money and the build manuals are very clear and well laid out.
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Post by RdM on Nov 12, 2020 18:49:28 GMT 12
Not exactly a kit, more a potential ambitious project, but observed Sowter U72 400W Tube Output transformer pair amplifier project www.trademe.co.nz/Browse/Listing.aspx?id=2857416520(Yes it could have been posted in TM discussion - should I duplicate it there?)
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