Was this the best pre-amp kit ever. Follow up with Audiophile parts. Different transistors & chips.

[@MichaelBeeny]

Watch this video first, then this will make more sense. kzbin.info/www/bejne/qGnGfJ-wod-Wgqssi=GnfFII_4uwmN954Y

[@ford1546]

Can you help me (Michael Beeny) ? I have a Naim NAP250 clone board from ebay. No matter which preamplifier card I use from ebay, it destroys the treble detail from 2k and brighter and makes it less detailed and clear. Have tried 3 completely different pre-amplifier cards with and without coupling capacitor and different op-amp ic. with the same result. With a passive preamplifier with the input selected and a 50k potentiometer, I don't have this problem. I've never been able to figure out why. could it be impedance mismatch or what do you think? The one preamplifier card I have only has a preamplifier ic. and resistors. naim nap250 clone card has 10uf tantalium capasitor on sound input.

[@pauldorman]

Enjoyable and informative video, thanks Michael! I hope you feel willing to "open" your channel again! KZbin took its sweet time showing us your videos, so now we've found you, you should keep them coming!

[@MichaelBeeny]

I will do my best, thanks for watching and commenting, much appreciated.

[@pauldorman]

@@MichaelBeeny Health challenges notwithstanding of course! We're not monsters! 😁

[@ryansupak3639]

It always makes me smile to see a new video from you. Thank you for the care and precision that goes into your work.

[@MichaelBeeny]

It's the only way Ryan, I know I'm not dead yet, if I see myself in a video lol I appreciate your kind comments.

[@doogee6157]

I thought you had retired from KZbin? still very nice to see you in good health and making great content again.

[@MichaelBeeny]

I have largely, I will make the odd video as and when I can.

[@osliverpool]

I did a similar comparison with a Chinese phono preamp kit a few years ago (claimed to be based on a Naim design). I built it with the original Chinese components, and later replaced them with "better" ones - eg Nichicon, WIMA caps (discrete circuit, so no op-amps). And it made no difference. I also used a Chinese power supply kit for it, and I had planned to replace the smoothing caps - but the ones that came with it measured very well with low ESR, so I kept them. (I love this series Michael, looking forward to the next installments).

[@ylou2876]

Sound quality, not waveform, is not entirely controlled by name brand capacitor nor transistor. The bottle neck, the critical path, could be anything in the path. Such as the soldering joint, connector ECT. This differentiate the gap between DIY vs name brand factory model. PCB itself is only part of the equation

[@osliverpool]

@@ylou2876 Yes, 100%

[@ronschauer839]

@@osliverpool I too agree.

[@MichaelBeeny]

Do you mean I have to make more? lol

[@osliverpool]

@@MichaelBeeny Ooh, yes please 🙂

[@hackedoff736]

Blimey I've missed these videos. Thank you Michael.

[@MichaelBeeny]

Thank you for returning again, your most welcome.

[@RobWhittlestone]

Great stuff Michael! Very interesting again! I wish I had more practical electronics experience - I feel tempted to have a go at DIY knowing what neat kit is available. I'm still using my exposure XI/XII preamp from 1986 - sounding as good as ever. So far I haven't found anything at reasonable price to top it. I'd therefore be interested to see a practical application of such a preamp module combined with input switching and output attenuation/gain control. Anything like that on the horizon? Meanwhile on to the Sugden clone! All the best, Rob in Switzerland

[@edmundzed9870]

Thank you very very much Sir. I love to finally see some measurements instead of hours and hours of bla bla and sounding "warmer" and even better if one puts in a stack of 1000 dollar bills for 1 meter speaker cable and even better when bi or triple wired :-) Glad I found you here on youtube!

[@beamer.electronics]

IMHO, the authentic LM4562 is a superb audio chip, but can be highly strung - I needed to place a decoupling cap from the +ve to 0VDC and another from -ve to 0VDC (on the chip pins), to stop it from occasionally bursting into HF oscillation. Smashing video, by the way.

[@MichaelBeeny]

Yes, you are 100% correct. Ron has done it on his unit, as yet I haven't. I'm waiting for a few LM4562 to arrive. It does suggest in the application notes to fix a single cap across the plus and minus supply rather than 2 caps to ground. Connect right at the pins of the IC sockets power in with ceramic cap of 1uf. Fits very well on the back of the PCB. Thanks for reminding me. Much appreciated.

[@ronschauer839]

I am indeed using LM4562 ICs in my boards now (both the "original" and "junkbox" versions). They make an easily measureable and listenable improvement. However, just as you said, they are highly strung devices. The data sheets for them recommend placing a capacitor as physically close as possible between the Vcc and Vee pins. I use 1uF ceramics for this purpose positioned directly underneath the socket. This keeps them nice and stable, and on a scope measurement you can see a reduction in ringing at signal step edges. Works like a charm!

[@olebjrklund8648]

Thank you again for a great and educational video, i think i will have to build this PreAmp some time this coming winter. Will order it from ebay or AliExpress and see when i get around to solder it together and start using it. As always, great and really understandable content from you. Take care and stay safe. Best regards from Norway .

[@MichaelBeeny]

Thank you for your kind words. I'm sure you will enjoy building this little kit. But mostly enjoy hearing it. Good luck.

[@ThePerkri]

Thank you for this! Just ordered one of these to play with. Looking forward to it!

[@MichaelBeeny]

Let everyone know the results.

[@ThePerkri]

@@MichaelBeeny Will Do!

[@ThePerkri]

@@MichaelBeeny Oh, because I’m lazy, I ordered the finished one….

[@peterlarkin762]

Mine just arrived. I intended to build it with the supplied parts, however I just tested the resistor leads and they are highly ferrous vs. branded resistors in my collection so they won't be going in. Also find that some carbon resistors in feedback circuits give a nicer sound. Nothing wrong with BC546/56, they're low distortion and don't really imbue much of a sonic character (better than 2n390x range). The JRC 5532 seems to be genuine. I've tested these against the Texas Instruments version and surprise, it sounds and measures exactly the same. Anyway I'll be putting an OPA2134 in... can't beat a FET input opamp if there's a volume pot before it.

[@cobar5342]

This is really good, so I ordered my kit from Aliexpress today - $19 AUD delivered and after GST I look forward to the Sugden. I love their gear

[@MichaelBeeny]

Ummm the Sugden?? I think you have made the right choice.

[@cobar5342]

Thank you. I am going to make this due to your inspiration

[@marknielsen8977]

Thank Michael, yet another cracking video.

[@mosfet500]

Michael, thank you. Okay, I bought one of these from eBay for ~$24 US as a built board, for $6 it wasn't worth building it as I have a lot of projects going on. Here's my take, the secret of this board is not so much in the high slew rate although it does add to detail, this board is rich in harmonics and that, I believe, was by design. I looked at FFT's and Bode plots, the second harmonics are what give this amp its sound quality, very much tube like. I can look an amp on a scope and pretty much tell what it will sound like but I did listen to it last night through my system. Here's my opinion of the sound - it's very much to my liking, very rich and warm, as I said tube like. I still have experimenting to do with it but it might replace my 6922 tube preamp design, I'll have to do an A/B comparison. Changing components and gain - don't do it! Lowering the gain and dampening the overshoot will reduce the warmth of this amp and unless you have a warm power amp you won't be happy, at least I wouldn't be happy. With that said, the best power amp you can buy today is class D, dealers won't tell you this but what is undeniable is class D's accuracy, you get out what you put in basically and that's what we want. This way we can contour the power amp with a preamp that suits our likes. That's exactly what I did with tubes before my class D amp. I tried this preamp with a Burr Brown DS1882 digital pot ( I still have testing to do on this) and ICE class D modules. The CD transport is the Audiolab 6000, Aries DAC and Dynaudio Heritage Special speakers. To get a better sounding transport and DAC you would have to spend a lot more money IF it would make a difference, honestly I'm not sure. Lots of hype but these are high end basic components that sound as good as some of the best. The ICE modules are 1200 watts each but I'm switching to their 200AS modules in future designs. The Heritage Specials speak for themselves. So this is what I'm testing these "cheap" boards with. I did notice the gain was lower than I expected. I don't like gain to low, several things suffer, one is dynamics, I find you can lose dynamics and flatten the sound when it's too low which is especially noticeable on on orchestral works . I will have to test it to see exactly what it is but they might have changed the gain, I'm curious what Accuphase did on their original boards and how close this is to their design. My preliminary thoughts are that this is an excellent design, keep the 5532 and the transistors, there's no reason to change them and it very well could reduce the wonderful harmonics. Further testing is warranted.

[@utenatenjou2139]

Hi, Mr. Ron's choice of using composite resisters, the brown one, for R input, I'd used them too. Reason are that they are very cheep to match for left-right value and some prefer composite over metal resister in R input. - I'm totally agree with you on being careful when sourcing opamp, buy them from reputable shops. Thanks for the contents as always.

[@ronschauer839]

Hi, I did not actually use carbon "composition" resistors, but perhaps this is just a difference in local terminology. In fact I haven't used any real carbon composition resistors in anything for several decades and do not even own any of them. I did however use carbon FILM resistors in some locations where I did not have the right metal film resistors available. 🙂 Because those locations have little voltage across them they did not seem to make much (if any) difference. My first choice for resistors in audio circuits is always metal film because of their low Johnson noise and because I can easily obtain them in 1% (or better) tolerances. The whole point of this bare board build was to use the best of whatever I had on hand just to see if it made any measurable or audible difference versus the components supplied in the kit. And honestly, it really did not make much if any significant difference. So if someone wants to build the boards up with "junk box" parts, believe it or not they will still sound remarkably good. 😁 Just be certain to use lower noise and higher gain transistors and genuine ICs.

[@utenatenjou2139]

@@ronschauer839 Hi, my bad, it is carbon FILM, resister. I'm not intended to promote any myth on using of exotic parts, thanks for reply.

[@ronschauer839]

@@utenatenjou2139 No problem. The whole point of this build was, again, to show that the basic circuit is the key to the design's performance, not "as much" the precise components that are used. Within reason of course... 😀

[@alanwild7746]

Sorry if this is a very feeble query from a non techy enthusiast,but my ready built Accuphase China clone has ICs labelled 5534 ,i.e.single amplifier. And the LM4562 is a dual amplifier,as is the 5532 I believe. So can the LM 4562 be dropped in as a straight swop for the 5534?

[@MichaelBeeny]

Sadly no, but don't worry the 5534 is a slightly better 5532 but in a single amplifier form.

[@alanwild7746]

Thank you.@@MichaelBeeny

[@andymouse]

Nice ! I'm a fan of the OPA1656, it is a Burr Brown product that might satisfy the Audiofools !

[@JBBrown-hh4rc]

After reading several comments on audio forums regarding the OPA1656, I decided to assemble another unit with an adapter board and pins to use with the Accuphase C-3850 clone preamp. Much to my surprise, the sound was totally different from what I had experienced before when I replied to you. As yet, I haven't determined what the problem was previously. I must say, I do like the sound of the OPA1656 and the OPA1612. Thank you for not "blasting" me regarding my previous response.

[@andymouse]

@@JBBrown-hh4rc No problem thanks ! :)

[@JBBrown-hh4rc]

After some listening tests, I found that I needed to lower the mid frequencies to get what I considered the best overall sound when using the OPA1656. Without this change, the vocals were way up front in the soundstage instead of being nicely mixed with the other elements of the music. Of course, this is my opinion.

[@andymouse]

@@JBBrown-hh4rc :)

[@gothjim325]

In some choice transistors, they can impart some (slight) desirable distortion and harmonics like vocals.

[@billkalina3089]

Hi Mike! I have ordered this preamp, and some 30p micas as per your suggestion. I noticed that someone on the sellers site said he was using BCW91, and BCW93 transistors. Never heard of them. I think i will house this in a previous preamp project, which didnt fly too well. As a matter of fact, perhaps i will also install that simple chip pre in the same box, and toggle back and forth for comparison. Cheers, Bill

[@ronschauer839]

The preamp Mike shows at the end is one that I have been using for many months with dual-7293 amp boards in an A/V amp for our den television. That combination works very, very well IMHO.

[@MichaelBeeny]

Hello Bill, I have never heard of that transistor either. All the equivalents on the Ti site are on the discontinued list. That does not mean they are not good. The only issue is that we have not tested them in this circuit. I would like and hope, the sellers have, however. If I were you I would, if it's not too late, buy from a seller that is using the same transistors, at least you know what to expect. Let me know what happens. Mike

[@billkalina3089]

@@MichaelBeeny no worries Mike, i was just stating that. But I do have several different types of small signal transistors about, some of the metal can types too. But would there be a sonic difference? Im becoming more skeptical.

[@billkalina3089]

@@MichaelBeeny that was a constructor who subd the trannies Mike. I will stay with the tried and true.

[@billkalina3089]

@@ronschauer839 I think the 7293 is a killer chip to build an amp around. Low cost, negligible distortion, runs pretty cool. I was honestly startled the first time i listened to mine. Couldnt believe the punch, the detail, the authority. If theres more bang for the buck, Id like to see it.

[@davidatrakchi2707]

I recieved the C3850 I ordered, initial checks shows that it is 100% transparent. I'm going to install it in an existing diy preamp I built long ago, it already has a nutube based stage and my intention is to allow a selection between "tube" flavour and straight amplification, simply according to the mood I'll be in😊 The only thing I changed was the opamp, I installed a good looking V5 opamp just because I had it around

[@MichaelBeeny]

I told everyone it was good. lol Thanks for the feedback, much appreciated.

[@Pete.across.the.street]

What do you check to see what % transparent an item is?

[@davidatrakchi2707]

@Pete.across.the.street my ears only, I'm listening to certain music through the C3850 and later switched to overlap it (while increasing the volume level to compensate the gain loose) and visversa many times. Tried it several time and I could not trace any noticeable change in tones, it sounds the exactly same as the direct connection except at higher level

[@davidatrakchi2707]

@@MichaelBeeny thank you Michael

[@jazzboy]

Your vids are great! Any recommendations for a good phono preamp kit?

[@MichaelBeeny]

I haven't owned a deck for over 30 years, so I cannot really comment, zero up to date knowledge. I'm sorry that's not exactly what you wanted to hear, but I like to be honest.

[@jazzboy]

@MichaelBeeny hey, no worries, and thanks for letting me know. Keep up the fine vid work.

[@new-kids-on-the-block]

thanks fore thank video we really like your videos end my c245 bild is amazing 😄

[@billkalina3089]

Hi Mike! How does this preamplifier differ from the Accuphase clone you tested previously?

[@zoelong6021]

I built the previous clone, and it has pretty awful THD=N

[@garygranato9164]

@@zoelong6021 i also built it and it sounded great , i have no way to measure THD !!. how did you measure THD??

[@didierelchardus3472]

I reverse engineered both and they are 99% similar. The 1st kit used a slightly different resistor value for one of his feedback resistors (680 Ohm instead of 470 Ohm). Also, the output transistors and emitter resitance values were different (ZTX transistors and 15 Ohm resistors instead of 22 Ohm for the 1st kit). Other than this, they use the exact same schematic

[@antonioandres25]

HI, the C8 cap is the cap in the base of the last four trans???? i dont see in the schematic, isn´t focused. Thanks

[@MichaelBeeny]

Look at 7.35 mins into the video. Bottom of the frame near the inputs. The 2 red caps are C8 originally 100pf. Hope that helps.

[@antonioandres25]

@@MichaelBeeny I seen this in your videos, but when you talk about C5 and C8, i have doubt. In others posts, talked about upper the cap until 220pf for more " a valve sound" , and i think that is in the feedback loop, in paralel with the 1Mohm. Thanks for your confirmation. Love your reviews. Hope you feel better.

[@stevenellerbruch6023]

Greetings from Chile Michael. As I write this my C3850 is out for delivery. I plan to build it using your suggested modifications and have decided to pair it with the TDA7293 amplifier. Based on your experience with these 2 products, what feedback resistor value would you suggest I use to best match the gain on the TDA7293? I really enjoy watching your videos and have learned a great deal. I hope you can keep them coming.

[@MichaelBeeny]

As I don't know what the output is on your input device, I would go for somewhere in the mid gain settings. You can always change it later if needed. Good luck with your project. Mike

[@stevenellerbruch6023]

@@MichaelBeeny After I read your response, it made perfect sense. I've assembled a streaming device using a Raspberry Pi fitted with an Innomaker DAC hat I purchased from Amazon. As per the company, the DAC puts out 2.1v RMS from the RCA connectors. My plan is to connect it to the C3850 and from there to the TDA7293 amplifiers. I must say that I was impressed by response I received from the company, They answered my query in less than 12 hours. Thanks again.

[@SandroMontecchiani]

Hi Michael, congratulations for the clear explanation, I was amazed by the good features of the preamplifier so I ordered one and now I have it here on my bench and I'm preparing to assemble it. A question regarding the power supply, have you measured how much current the device absorbs? just to size the transformer correctly... many thanks for any suggestions !

[@MichaelBeeny]

It uses under 50mA each rail, so really any transformer will be fine with 250mA minimum secondary will run very cool. I simply used one I had to hand for testing. As for physical size, it's what fits for you. The transformer simply needs a 15/0/15 volts secondary.

[@aldogentile245]

A very time demanding comparison Excelent. By the way, when are you going to describe the two preamplifers you mentioned at the end of this video?

[@stuarthossack7906]

Hi Michael, In your video about the potentiometer affecting the frequency response at the input, you mentioned that you'd be looking at an input buffer (or did I misunderstand?) - any news on this? Many Thanks.

[@MichaelBeeny]

You don't need anything else; this board is a preamp and buffer. If you do the couple of board mods, I suggest in this and the previous video. Performance will be near to perfect.

[@petertimp5416]

Good job!….thanks😊

[@MichaelBeeny]

Thank YOU, Peter.

[@didierelchardus3472]

Great test report, thanks ! Which is the C8 100pF capacitor you are suggesting should be adjusted down to 27pF ? Is it the one in parallel with the 47k input resistor or the one which is in parallel with the 1M resistor ?

[@MichaelBeeny]

It's the one in parallel with the 47K resistor. These details are clearly shown within the 2 videos as well as board layout and full circuit diagrams.

[@robh9079]

Any thoughts on experimenting with default negative gain and either a gain pot(as well as a volume)(lin or log...?) or a gain switch - say -3db and +6db. Might make an interesting and flexible unit. My partner likes music very low at times and I'm always scrabbling round the 7 o-clock position! N.B. Fback resistor say 1.5k - then parallel pot(wired as variable resistor) with a series resistor to set minimum resistance(and max gain)?

[@ronschauer839]

Actually, to make the measurement waveforms, that is sort of what I did. It was only a "convenience" for me while doing them. What you might consider would be using the 100 ohm resistors for the feedback loops as supplied, and adding 2K pots in series with them. This should provide a good overall maximum gain control without compromising the circuit performance. I hope this helps.

[@Qualitaetspruefer]

It seems like this preamp have a lot of gain... How about buying one of those kits as a headphone-amp?

[@MichaelBeeny]

We are testing it as a headphone amplifier right now, I will report back as soon as we reach a conclusion. Looks promising.

[@ronschauer839]

@@MichaelBeeny Yes, it is in the works.

[@maniacaudiophile]

My own interesting experience is that... More gain other than all the down sides, also seems to enhance the particular sound of the amplifier, good and bad. Lower the gain, more neutral. IMHO, unless we are talking about MOSFETs, I haven't seen similar BJT being a huge factor in sound signals. If we are talking about MOSFETs, Hitachi and the other lateral MOSFET seems to sound quite good. While the later IR MOSFETs seems to be terrible unless you get them really hot, and even when really hot, they are not that great. (My source: self built M3, B22, dynalo, dynahi, and a pile of different power amps I've collected over the years, with particular emphasis on Hitachi lateral MOSFETs in TO-3 packages.) For fun tho, would you consider trying out some higher grade capacitors? Often a few of the Nichicon UKZ or Elna Silmic II on the power bypass would do magic. For comparison, Panasonic FC/FM series capacitors will make quite a contrasting comparison. Since they are just small 10~47uF bypass caps, they will be quite cheap to try out, even if you use those series that i had mentioned.

[@peterlarkin762]

Same feelings here on all the above... UKZ caps are one of the very few that stand the test of time (for my ears). I use them on all opamp decoupling scenarios, and use Panasonic FC or FMs just after the regulators for balance. And the LatFETs! Best thing since sliced silicon wafers. Built a load of BJT amps (including Elvee's Circlophone) and then a Rod Elliott P101 with parallel Exicon latFET s (Based on the Hitachi ones, ). Well I haven't made an amp since, it just does everything right.

[@maniacaudiophile]

@@peterlarkin762 I tried some FC and FM with my first DynaHi and that was a disaster. Every complaints that tube head has about solid state, they are all there. Found some ROE EK(i think, it is those with brown plastic shell and bright yellow sealent, we can them ROE coffee caps in Taiwan) NOS caps to replace them and it was all good again. It was quite a shock to me and friends that just 2 tiny caps per channel had that much influence. Thus my suggestion to Dr. Gilmore to put the caps closer to load on the next revision, and he agreed. FC/FM while sounding harsh when used to bypass an amp, it should be perfectly in its elements for DACs and other circuit's digital section(duh, Panasonic likely engineered then for that use). It is still a good cap from a good manufacturer. To me, half of the fun is listening, half of the fun is messing with stuff and see what happens. Recently recapped a Nikko Alpha 230, and it was god awful when first powered on. Left righ imbalance, rough sounding, muffled in all freqs, you name it... And the veil slowly dropping, left right don't sound weirdly imbalanced over the first few hours of listening. Actually got pretty good after a while.

[@maniacaudiophile]

@@peterlarkin762 by the way, old PA amps are a good way to get nice Hitachi lateral MOSFET amps. I got a few examples from Ashly, and they are not too hard to rehab into a nice premium stereo power amp.

[@peterlarkin762]

@@maniacaudiophile Thanks! I'm always on the lookout for old parts. Adding those to my list:) I've started fixing a lot of PA amps locally so hopefully they will materialise. My first amp (LM3886's) was full of Panasonic FCs. Also a disaster! Took a while to learn the art of audio design. I think I've seen those ROE caps before but not common in Ireland. I do collect Callins vintage poly caps though: probably the only caps ever made in this country (60's) and 80% measure perfectly. Sound far better than WIMA etc. They just don't make components like they used! P.S. Which diy Lateral mosfet amp is your favourite so far?

[@maniacaudiophile]

@@peterlarkin762 I actually don't have any DIY lateral MOSFETs amps. I bought a few factory made amps with it. I find the design quite nice and decided to just modify it for home use. Taming these PA amps for home use is not too hard, mainly involving tossing out a lot of safety features that are needed in commercial environments, but have no use in a home setting.

[@antoniojoseandreomartinez9710]

👍♥️🫂. Muchas gracias 🫂👍

[@garygranato9164]

how come Ron didnt use the bc550/560 ?

[@MichaelBeeny]

He did, one channel used the BC option, the other used the 2N version clearly show by the different colour traces on the scope. The original BC range gave the best results, only just, they were very close.

[@garygranato9164]

@@MichaelBeeny hi michael the bc550c and bc 560c are the low noise 'audiophile' versions of the bc546/bc556. my point was if the circuit was already designed for the 546/556 then the 550/560 would be the natural upgrades. i am a noob, please correct me if i'm wrong. nice to see your making more videos and looking well. regards gaz

[@ronschauer839]

​@@garygranato9164 The point of my bare board build was to use "different" components to see and hear what (if any) difference they might make. I totally agree that the 550/560 parts are better, I just did not have any on hand. And I wanted to try something different anyway for the sake of comparison. In my testing the BCxxx parts were indeed superior to the 2Nxxxx parts, which was not at all a surprise. However, it was worth trying, IMHO. Excellent observation though..! 🙂 As part of the build I did use high quality film capacitors and "audio grade" bulk filter capacitors wherever I could, including in the feedback loop. And I do feel that the better capacitors made a *slight* improvement, mainly in the bass response. If you have them, you should use them. In fact I will be retrofitting them to the "as-shipped" board. Also, I did not have metal film resistors for all of the required values and so I used carbon film (not carbon comp) resistors for the ones I did not have. I did not observe any added noise from them, but then they were used in positions that had little voltage across them, so that too was expected. And of course I used 1K ohm cermet trimmers in series with the feedback loop 100 ohm resistors so I could easily change from high to low gain for testing. Again, no added noise was noted. I really like these boards, but stay tuned for Mike's next video on the Sugden clone preamp. There may be a few surprises in it...

[@familiekruit6068]

Try swapping out the opamp with a Burson V7 Vivid. You'll be amazed!

[@Чемы]

Здравствуйте Михаил. У вас на канале есть видео снятое три года назад, там вы сделали обзор предварительного усилителя Accuphase C3850. Как вы думаете какая из них будет получше?

[@sitaram.electronics]

Very nice sir🎉🎉🎉❤❤❤

[@PAC-fp9hy]

Does anyone know what the analogue input and output connectors are (standard 8 pin pcb connector?). I am considering an analogue switch going in and then handing off the an ICEpower ASX250.

[@doogee6157]

Texas instruments 5532's sound amazing , much better detail then the Chinese chips.

[@Paxmax]

Thank you! Molto Beeny! 😃👌

[@BrianHG.Ocean.Fitness]

Showing square waves instead of sine waves... Especially at the higher frequencies. You will not see if the opamps have cross-over distortion in their waveforms. And remember when doing said test that you need to load the output with a length of line cable and proper ~50k and 10k load with a capacitive load as well. Without such a setup, we will never know if that output spike seen in your square wave may end up mutating into an oscillation or ringing.

[@MichaelBeeny]

I have NEVER seen crossover in any of the op amps I have used so far. Bias is normally preset internally and not something you can mess with. Should you find crossover it will be internal, but I doubt such an op amp would ever hit the market. I do use sine waves on power amplifiers to show clipping and max power, but preamps are a bit boring and generally not much to see. I do test sine waves to measure frequency response.

[@BrianHG.Ocean.Fitness]

@@MichaelBeeny crossover distortion is uncommon when everything is done OK and you are not using Chinese knock-off op-amps. However, it can appear as you approach the opamp's gain bandwidth product with an excessive capacitive load on the output outside the op-amp's drive capabilities. My comment's purpose was to illustrate since you are already analyzing the output, such an analysis might as well be done to confirm that no such problem exists. EG: Measure the output of a cheap LM358 opamp un-loaded and it will look fine through 20khz, feed that output through a 3 meter cable to an audio amp with a 1k, 1000pf load input and with a 1khz sine wave going through, you will see a slight dent in the waveform just below and above the 0v center of the sine wave.

[@ylou2876]

​@@BrianHG.Ocean.FitnessThat dent,is called reflection. Your transmission line did not terminate properly. The duration from low to the dent, is proportion to the length of the cable. It is actually the round trip of the cable length.

[@BrianHG.Ocean.Fitness]

@@ylou2876 Cable length is too short for a 1khz sine wave to show dents on the transition point of the sine wave. High quality op-amps or class-A output pre-amps will not produce the problem.

[@georgeogrady449]

Hope they make next up 32 bits audio system up to 40 bits

[@robh9079]

$500,000,000,000? - mmm, 'midfi'😄 Thanks for vid👍 - have picked up one of these really cheap for a play! I wonder if up-rating+grading the power caps/transformer will make an improvement.

[@MichaelBeeny]

You don't have to wonder Robh, See my follow up video, I've already done just that, so you don't have too.

[@robh9079]

@@MichaelBeeny thanks- just bought one on special - £3UK inc delivery! Thought it might be a mistake and it's just the board - no - I have all the parts in front of me!

[@michaellundsrensen2292]

❤❤❤

[@marcsmithsonian9773]

And according to your subjective opinion which is the best power Amp kit ?

[@MichaelBeeny]

Not such a simple answer on this one. Depends on many external things. As a general answer, this will cover most requirements. Avoid class D, class A and silly low powered 5/6 watt so called HiFi. Number one is the L12/2. Very closely followed by the Dual version of the TDA7293. I have covered them both on my channel. Both offer extremely low THD, high power (the L12/2 having more power) clean natural sound and great dynamics with very high slew rate (speed) The 7293 in THIS version is not available as a kit sadly.

[@MichaelBeeny]

Like at bit of fun?? kzbin.info/www/bejne/qJe6oYuMiKybpZYsi=jVH5wPRMMfNtr5X0 Hope you get it!

[@ford1546]

can you help me (Michael Beeny) ? I have a Naim NAP250 clone board from ebay. No matter which preamplifier card I use from ebay, it destroys the treble detail from 2k and brighter and makes it less detailed to clear. Have tried 3 completely different pre-amplifier cards with and without coupling capacitor and different op-amp ic. with the same result. With a passive preamplifier with the input selected and a 50k potentiometer, I don't have this problem. I've never been able to figure out why. could it be impedance mismatch or what do you think? The one preamplifier card I have only has a preamplifier ic. and resistors. naim nap250 clone card has 10uf tantalium capasitor on sound input

[@ylou2876]

Did you try the real clone NAC42.5 + HiCap ? Some clone cut half of the circuitry ? The sound should be very dynamic . And check the nap250 circuit against real one. Hope this help

[@ford1546]

@@ylou2876 Talking here about connected preamplifier cards vs passive preamplifiers. Why I find that treble from 2k to brighter becomes less detailed and good with active preamplifier vs passive, only potentiometer? (NAIM NAP250 MOD CLONE) (P7 mini preamplifier) (HiFi JRC5532DD Preamplifier Board)

[@ylou2876]

​@@ford1546with NFB, frequently response are all pretty good no matter which circuit. However, waveform is not equals to sound quality. NAP 250 use tamtalum capacitor as the uniquie sound signature, thus the matched preamp, need to have similiar characteristics. Tantalum capacitor typically highlights mid range,needs to do this for the entire signal path. I also have mini p7

[@ylou2876]

Does your NAP 250 has power regulator ? Almost same power transistor as the power stage ? Or the simplified one ?

[@ford1546]

@@ylou2876 ? I don't think you understand what I'm asking you or trying to explain! I connect 3 types of preamps to the naim nap250. not at the same time of course. Always when I connect a normal op-amp ic. bassed preamplifier card, I always get worse treble with poorer details than what I get with a passive preamplifier only with a variable resistor. naim nap250 has no power regulator but I use an SMPS power supply card designed for audio at 500w

[@jmi5969]

That's the problem, there is too much gain already... almost every source around me, from reel-to-reel to vinyl to shiny plastic discs needs volume down to 10 o'clock max. Whether it's fed to triode monoblocks or a simple transistor integrated amp ("simple" meaning no preamp stage, just a volume pot connected to output stage). So while this board may be a fine gain stage and a fine line driver as such, it will cause more problems downstream.

[@opionair5257]

That is also my magic formula. At normal room volume, the volume knob should be at 10 o'clock

[@MichaelBeeny]

Hi jmi. You clearly do not need a preamp. Might be worth using a simple buffer to isolate the input source from the power amp and keep impedances right. I may have just the thing planed in an upcoming video.

[@MichaelBeeny]

Jmi If you use a 1k resistor in one of the feedback loops the gain will be only 3.45dB with increased S to N, even lower distortion and noise. This is in fact the mode I am using right low.

[@jmi5969]

@@MichaelBeeny That's fine, but for me a short twisted pair of copper wires works even better. The sources seem to have no issues driving 1.5-meter cables. And yet I'm building a preamp - not for gain, but for convenience (more inputs, EQ and other unhighendian stuff).

[@georgeogrady449]

Different

[@davidfoster5906]

Why do pre amps cost so much when you can buy good amplifiers or even decent integrated amps,with larger transformers and capacitors a fraction of the price.

[@MichaelBeeny]

Well David, they don't need too as the basic preamp I show here proves. It also becomes cheaper if built as part of the main amplifier. Like everything in life, we always get someone that adds all kind of extras to make the price as high as possible. Look at my follow up videos, that kind of proves the point.

[@peterlarkin762]

If you put this preamp pcb in a case, with a tone control module, transformer, pots, knobs, source selection switching, remote control, 10x RCA sockets on the back, maybe a balanced input buffer and a phono preamp, plus the chassis and the labor, distribution, marketing... It really does cost a bit, then manufactures add 50 to 100% extra for profit. I make my own gear with high quality home made chassis' and my preamp cost about 400 euros in parts. No boutique or unobtanium bits. Things are a rip off these days but you gets what you pays for.

[@ford1546]

Hello. What's the point of a transistor based preamplifier when you have a preamplifier ic in the circuit? you get the sound of that ic. Everything is not measurable! A good 100% ic. bassert can also measure similar. A preamplifier should be transparent and not have its own sound

[@davidlong1786]

Everything that is audible is measurable. Any subjective wishful thinking is not.

[@ford1546]

@@davidlong1786 What I really meant was that if you are going to have a transistor based amplifier, why have an op amp ic in the chain? Then you will get the sound type of the op amp ic. oh you want to destroy the preamplifier if you know what i mean?

[@davidlong1786]

@@ford1546 So how does that OP amp sound? Any measurements that show it's not up to par with the transistors?

[@paulperry7091]

What do you think are inside preamplifier chips? Transistors are. And being specifically designed for the job, probably just what is needed.

[@ford1546]

@@paulperry7091 If you try 10 pcs. different op-amp ic. then you get 10 different sound types. If you search the internet for op-anp ic, you will soon find out that people use them as a kind of EQ. to improve the sound quality of a device. especially on hifi forums there is a lot of discussion about this. op-amp ic has its own sound. Although there are not very big sound differences between them, there are sound differences between them. If you insert one op-amp. then you get the sound of it if you understood.

[@honeydavis5568]

All decent preamp are way better than speakers and microphone capsules. The mose expensive mics have a preamp in them made of one tube or fet. So buy a cheap good reciever and spend your money and time on speakers. I love JBL. Find speakers you love. High end over powered amps not recommended by me. Who am I? A damn good listener. But I don't listen to superstition by audiophiles.

[@georgeogrady449]

If computer can do it sure audio system can be same

[@Nickytheshaft]

Hello @MichaelBeeny I am looking to build this "clone" do you recommend this kit over the one you presented in your previous video? kzbin.info/www/bejne/jX3JZpRtp8aDgNE

[@MichaelBeeny]

It's almost the same thing. This is just the basic preamp; the other board has input selection added as standard. Choose the one that is best for you.

[@Nickytheshaft]

Thanks for the response. This kit is sold out as diy. I like soldering my boards so I guess I will go for the other one then

[@valentinvalentin8916]

A lot of technical and data information and nothing about sound quality, emotions...

[@MichaelBeeny]

Thats because that is subjective. An opinion. The internet is overflowing with people that have swallowed a dictionary. In my humble opinion, I have NEVER found any amplifiers that sound great but measures badly. Those that do measure badly usually add something. You may well like the things it adds but it's not true HiFi which should NOT add anything but gain.