Well, there are other "problem": maybe there are too many DIY class A amplifiers, and many doubt which to build, even though the ALPHA has very good measurements!
And class A need speakers with high/very high sensitivity, and better with true nominal impedance near to 8 Ohms I think.
And, no less important, fewer and fewer people appreciate good recordings, with unadulterated voices and acoustic instrumentation and high dynamic range (DR).
That is why the commercial and DIY market must be shrinking year after year.
As it happens in other fields, such as (good/true) literature. For decades the books are worse written, use less vocabulary and contain a lot of spelling mistakes, at least in Spanish. Now I read little, but years ago I got fed up and decided to read books written years ago. It is the same philosophy that I use with music. I was a regular at the Public Library of Tarragona, to which I ordered the purchase of many books to make it richer, tired of it being full of best sellers, so badly written in its vast majority. Now, the few that I read, I do it from the screen.
And class A need speakers with high/very high sensitivity, and better with true nominal impedance near to 8 Ohms I think.
And, no less important, fewer and fewer people appreciate good recordings, with unadulterated voices and acoustic instrumentation and high dynamic range (DR).
That is why the commercial and DIY market must be shrinking year after year.
As it happens in other fields, such as (good/true) literature. For decades the books are worse written, use less vocabulary and contain a lot of spelling mistakes, at least in Spanish. Now I read little, but years ago I got fed up and decided to read books written years ago. It is the same philosophy that I use with music. I was a regular at the Public Library of Tarragona, to which I ordered the purchase of many books to make it richer, tired of it being full of best sellers, so badly written in its vast majority. Now, the few that I read, I do it from the screen.
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And I wonder why there's no more B.B.'s built. Maybe it's because active cooling, don't know. Am I the only one who has made casing around it? Well, as said before: friend has my B.B.'s now, and there is another pair of pcb's on their way with cap mx from X 
so going to build another pair of monos.
so going to build another pair of monos.
Oh, Maty, you and I are getting old, huh? And Socrates complained bitterly about the young today, saying they knew nothing of culture, social behaviour, and history.... not to mention their written words.
I believe in all genres, even Gangster Rap, there is excellence as well as dross. I cannot read easily now, since a brain injury, but oddly I can still write, though not so well these days. We move on........
I exhort you to read 'A Day in the Life of Ivan Denisovich'. Fyodor really wrote well!!
Hugh
I believe in all genres, even Gangster Rap, there is excellence as well as dross. I cannot read easily now, since a brain injury, but oddly I can still write, though not so well these days. We move on........
I exhort you to read 'A Day in the Life of Ivan Denisovich'. Fyodor really wrote well!!
Hugh
Je, in my adolescence I read the book wrote by Solzhenitsyn, The Gulag Archipelago.
My friend Juan Pedro Quiñonero, one of the best journalists and Spanish writers -but very little apreciated like a writer, when he worked for RTVE was the first one that interviewed him when he came to Spain, 1975.
[Spanish] Solzhenitsyn y el Gulag, en Madrid
[Spanish] De la inexistencia de Espana. Presentacion. | Nauscopio Scipiorum
For years I was taking care of his blog. He is the dean of the Spanish correspondents in Paris.
I take note.
My friend Juan Pedro Quiñonero, one of the best journalists and Spanish writers -but very little apreciated like a writer, when he worked for RTVE was the first one that interviewed him when he came to Spain, 1975.
[Spanish] Solzhenitsyn y el Gulag, en Madrid
[Spanish] De la inexistencia de Espana. Presentacion. | Nauscopio Scipiorum
For years I was taking care of his blog. He is the dean of the Spanish correspondents in Paris.
I take note.
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The same goes with food. Try cooking food usiing basic or similar ingredients and recipes from 200yrs ago. My recent hobby in cooking 18th century American Colonial dishes has opened up some very simple, healthy, and great tasting dishes. Modern store bought food has too many chemicals and ingredients with strange names. Ingredients should be something we recognize and can touch and on a farm, stream, lake, ocean or or pasture.
Amazing "eye candy" in the power hungry class A world. The use of all those
CPU thermal solutions is amazing.
I had to look at this "opposite end" of the audio world (as I leave it) for -
Class AB + G(ec) and SMPS.
XRK , warm listening room ??
OS
Hi OS,
It’s snowing here in Northern Virginia and the listening room is in the basement so I can use all the Class A heat I can get. The room has new wood flooring and drywall since the flood last July. It sounds a bit reverberant now sans carpet. I need sound treatment panels and maybe an area rug. But it’s nice to listen to a good Class AB amp once in a while too.
Your new Green amp is going to be so cool running it’s not useful as a heater in winter.
Greetings to all,
I always read you with great interest.
I would like to build a class A power amplifier and would like to know what the different sound characteristics of the 3 versions of ALPHA are: 8ohm, 4ohm and BB compared to the JLH2005 I am using now and the Krell KSA50 on which I would be was initially oriented.
Thank you for your attention, renewing greetings to all of you.
Mleod
I always read you with great interest.
I would like to build a class A power amplifier and would like to know what the different sound characteristics of the 3 versions of ALPHA are: 8ohm, 4ohm and BB compared to the JLH2005 I am using now and the Krell KSA50 on which I would be was initially oriented.
Thank you for your attention, renewing greetings to all of you.
Mleod
Hello Mleod,
Thanks for your interest. I have only heard a JLH headphone amp so can only extrapolate based on topology and what I heard as headphone amp. It is a singleton input which is good from sound quality aspect of not having higher 3rd order than 2nd order harmonic distortion and it is quasi complementary output. Also maybe circa 10w or maybe more with updates version. I think sound signature may be similar but Alpha will have better bass authority and has no DC offset drift since self correcting with balanced input stage (that I has Lender VAS) and probably lower overall THD sigh Alpha. The Alpha BB has better damping factor circa 300 and will drive most speakers as if it were a 100w Class AB amp. I don’t know why that is but perceived sound quality is higher at high SPL compared to similar power Class AB.
I have not heard the Krell KSA50, but looks like a balanced input stage that may have higher third order harmonic distortion than second - dunno, just guessing based on schematic. KSA50 is also a ~30yr old design (and JLH is 50yrs old) vs the Alpha which is really quite state of the art.
It’s a really simple amp to make and has zero adjustments. You can try it and it won’t be a huge investment of parts or time if going with Alpha 20. Same standard +/-24v PSU of typical 25w Class A amps. Really can’t go wrong with the Alpha.
Thanks for your interest. I have only heard a JLH headphone amp so can only extrapolate based on topology and what I heard as headphone amp. It is a singleton input which is good from sound quality aspect of not having higher 3rd order than 2nd order harmonic distortion and it is quasi complementary output. Also maybe circa 10w or maybe more with updates version. I think sound signature may be similar but Alpha will have better bass authority and has no DC offset drift since self correcting with balanced input stage (that I has Lender VAS) and probably lower overall THD sigh Alpha. The Alpha BB has better damping factor circa 300 and will drive most speakers as if it were a 100w Class AB amp. I don’t know why that is but perceived sound quality is higher at high SPL compared to similar power Class AB.
I have not heard the Krell KSA50, but looks like a balanced input stage that may have higher third order harmonic distortion than second - dunno, just guessing based on schematic. KSA50 is also a ~30yr old design (and JLH is 50yrs old) vs the Alpha which is really quite state of the art.
It’s a really simple amp to make and has zero adjustments. You can try it and it won’t be a huge investment of parts or time if going with Alpha 20. Same standard +/-24v PSU of typical 25w Class A amps. Really can’t go wrong with the Alpha.
I was thinking about retrofit in a JLH '96 build. Yeah, I have opamp PSU at it. Just a few Ampers more.
Greetings to all,
Thanks X ... I'll tell you that frankly some of the characteristics you've set out would go in the right direction, what I'd be looking for.
Expressing briefly I would like something that could drive with more authority my OB, in particular the low range that if present, the JLH according to me can not express the same qualities that I can appreciate on the medium-high fq.
However, I must admit that the fact that the device is state of the art rather than a remake of an old one is a relative concept for me, I would give the greatest importance to the sound result, regardless.
However, I think the BB may be the one best suited to my expectations, but I have some doubts about the cooling system that goes beyond any past experience, and I would like to know if there is a real possibility of a traditional assembly and possibly with what precautions.
To tell the truth I would have already started to procure elements for the PS: 2 toroidal transformers from 500VA with voltages 36-18-0-18-36 V and 4 electrolytic capacitors from 0.033F 68V, thinking about the KSA50, and I wonder if they could also be used to feed the BB. I would like to know your thoughts about it. Sorry for lenguage.
Thanks bye.
Mleod
Thanks X ... I'll tell you that frankly some of the characteristics you've set out would go in the right direction, what I'd be looking for.
Expressing briefly I would like something that could drive with more authority my OB, in particular the low range that if present, the JLH according to me can not express the same qualities that I can appreciate on the medium-high fq.
However, I must admit that the fact that the device is state of the art rather than a remake of an old one is a relative concept for me, I would give the greatest importance to the sound result, regardless.
However, I think the BB may be the one best suited to my expectations, but I have some doubts about the cooling system that goes beyond any past experience, and I would like to know if there is a real possibility of a traditional assembly and possibly with what precautions.
To tell the truth I would have already started to procure elements for the PS: 2 toroidal transformers from 500VA with voltages 36-18-0-18-36 V and 4 electrolytic capacitors from 0.033F 68V, thinking about the KSA50, and I wonder if they could also be used to feed the BB. I would like to know your thoughts about it. Sorry for lenguage.
Thanks bye.
Mleod
The CPU coolers and noiseless fan (Noctua PWM brand) make cooling easy, compact, inexpensive, and most importantly - cool temperatures. For the Alpha BB, the single IXYS MOSFETs dissipate each about 100w. You will need to quickly "spread" that 100w flux which originates from the 2cm x 3cm metal therm pad on the back of the MOSFET to an area the size of almost two traditional Class A heatsinks of a typical 4U tall x 300mm deep x 25mm long fins. Even a copper plate cannot do this and heatpipes would be needed to transport that heat away from the localized area. If you look at a traditional Class A that uses passive radiators, they will spread the heat load over several MOSFETS so that each will not be more than about 25w to 30w of dissipation. In a Pass X1000 amp, it is spread over 32! IRFP240/9240's. We use a single large 460w IXYS MOSFET because it eliminates matching and provides a simpler build with fewer components. I admit that it is not a traditional looking big frame Class A amp - but why not use commodity state of the art thermal solutions developed for high tech computers that routinely dissipate 150w over a die with a billion little transistors running at 3GHz?!
The problem of fan noise, I can personally attest, has been eliminated if one uses a Noctua PWM. That company has invested heavily on CFD simulations and used all the tricks in the book to reduce fan noise, and it really works. There is no comparison with another brand's so-called "quiet" fan. I mean the Noctua's are INAUDIBLE with my ears 2in away - cannot tell it is powered up based on ears. I am not paid by Noctua to say this and I don't have any stock in their company (but maybe I should). They are just that good. Here is a summary of all the tricks they throw at a fan to make it silent. They cost more at $15ea vs $5 but IMO, worth every penny. Silence in an amp is golden. The mild 60Hz hum the trafo makes is louder - seriously.
Technologies
Regarding the trafo and caps you got for Krell, probably buy one more of the same trafo and use a cap multiplier and you will be good. You will need a double set of secondaries to generate the dual rails per channel. 22mF per rail per channel with cap Mx is enough but of you have 33mF, even better.
The Jason Keutermann MrEvil cap Mx has been used by Vunce, and I just built one myself - it is very good and suitable for supplying lots of amps continuously with a variable adjustable output voltage. My only changes to it are to use an external square puck bridge rectifier and external MOSFET (with flying leads) as the on board mounts do not have sufficient room for a decent heatsink. The bridge gets hot and so does the MOSFET. But you save from having to get only a pair of 22mF caps vs 8 so cost savings is substantial, and my measured ripple at 5 amps is 2mV. I don't think 8x33mF caps CRC can touch that.
Here is an example of my JK Cap Mx (only positive rail populated) undergoing testing at 4.7amps and putting out 37v for my MOAMOFO which dissipates 150w to 160w per IXYS MOSFET. You can see how I mounted the bridge and main MOSFET for the cap Mx remotely on a small heatsink. There is a fan there but I found it can work passively cooled if fins angled vertically.
Attachments
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Why class A ALPHA 20 watts?
Just now I have read the review of First Watt SIT-3.
First Watt SIT-3 power amplifier Measurements | Stereophile.com
* 8 watts (8 Ohms) with THD+N 1%
* 16 watts (4 Ohms) with THD+N 1%.
Just now I have read the review of First Watt SIT-3.
First Watt SIT-3 power amplifier Measurements | Stereophile.com
* 8 watts (8 Ohms) with THD+N 1%
* 16 watts (4 Ohms) with THD+N 1%.
ALPHA 20 with premium components
Fig.4 First Watt SIT-3, both channels driven, distortion (%) vs 1kHz continuous output power into 8 ohms.
Fig.8 First Watt SIT-3, spectrum of 50Hz sinewave, DC–1kHz, at 1Wpc into 8 ohms (linear frequency scale).
It does indeed eek out a bit lower distortion with Vishay Dale resistors and all Wima and Silmic caps, now about under 0.006%THD for 2.75vrms into 8ohms:
Hi Maty,
Nice results for the SIT3 from NP, and very good figures from XRK971 on the ALPHA 20. At the risk of boring you with information you know well, let me offer my thoughts!
Both are Class A, but the SIT uses a SOTA silicon carbide transistor which is unique, expensive, and difficult to source. The circuit is classic minimalism from NP, a very well designed amplifier of very different topology to the ALPHA.
I note that the H2 on the SIT3 appears at -55dB. This is about 12dB lower than a single ended triode amplifier, which many people really like for the rich, lush sound. The SIT3 would have a marvellous warm, rich sound and with the right speaker would sound wonderful. The harmonic profile is linear decreasing.
The ALPHA is a very difficult beast. Again, it uses a NP innovation, the active current source, but the output devices are complementary mosfets, cheap as chips, but running at high dissipation (40W each). The H2 is far less, -85dB, so it would sound neutral, not rich/warm like the SIT3. Those who like to hear no distortion, no addition to the sound, absolutely clean and quiet, would like the ALPHA, and those who like the tubey, warm sounds of H2 would love the SIT3.
Audio is as much entertainment as it is technical objectivity. You choose what you like, and make to apology to any preferences. If you do, then you might prefer to follow political correctness..... in both amplifiers, the harmonic profile is still linear decreasing, the way most Class A amps deliver so nicely.
For myself, I would like to own BOTH amplifiers, and switch from one to the other according to whimsy and my musical tastes. There can be no objectivity about the subjective.........
Hugh
Nice results for the SIT3 from NP, and very good figures from XRK971 on the ALPHA 20. At the risk of boring you with information you know well, let me offer my thoughts!
Both are Class A, but the SIT uses a SOTA silicon carbide transistor which is unique, expensive, and difficult to source. The circuit is classic minimalism from NP, a very well designed amplifier of very different topology to the ALPHA.
I note that the H2 on the SIT3 appears at -55dB. This is about 12dB lower than a single ended triode amplifier, which many people really like for the rich, lush sound. The SIT3 would have a marvellous warm, rich sound and with the right speaker would sound wonderful. The harmonic profile is linear decreasing.
The ALPHA is a very difficult beast. Again, it uses a NP innovation, the active current source, but the output devices are complementary mosfets, cheap as chips, but running at high dissipation (40W each). The H2 is far less, -85dB, so it would sound neutral, not rich/warm like the SIT3. Those who like to hear no distortion, no addition to the sound, absolutely clean and quiet, would like the ALPHA, and those who like the tubey, warm sounds of H2 would love the SIT3.
Audio is as much entertainment as it is technical objectivity. You choose what you like, and make to apology to any preferences. If you do, then you might prefer to follow political correctness..... in both amplifiers, the harmonic profile is still linear decreasing, the way most Class A amps deliver so nicely.
For myself, I would like to own BOTH amplifiers, and switch from one to the other according to whimsy and my musical tastes. There can be no objectivity about the subjective.........
Hugh
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With H2 at -55 dB, the SIT-3 is more adequate to play small groups, with few acoustic instruments and natural voices - without autotune (vade retro satana).
Alpha 20 has more wattage (18.8 watts at 8 Ohms I think). With H2 at -85 dB and is more all-rounder, suitable for all kind of music.
I like amps with very low distorsion and with good/high SNR-A too -> more detailed and 3-D sound. And whose power section filter very well the noise of the electrical grid.
Alpha 20 has more wattage (18.8 watts at 8 Ohms I think). With H2 at -85 dB and is more all-rounder, suitable for all kind of music.
I like amps with very low distorsion and with good/high SNR-A too -> more detailed and 3-D sound. And whose power section filter very well the noise of the electrical grid.
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Well X I have finally begun my Alpha BB. Sadly I have had a cart on Mouser for about 7 months with a lot of items some for this build and others in progress and either left some parts out or don't remember what some of them were to be used for.
Oh, well another birthday has come and gone. Lost a few more grey cells. Having to read again all of the posts to figure out what I have forgotten.
I have built the same JK cap Mx you and Vunce are using and plan on placing the bridge outboard. For the current needs of the BB how large of a heatsink for this parts would you guess. Do I need something like the heatsinks on the 4U case in the store or smaller? Would some Wakefields on the Mosfets work? Ballpark is ok. I am still struggling with a case either stereo or monoblocks like Juntin built. Both amp boards are mostly completed except for the missing parts I forgot to order.
I have another cart going on Mouser to cover the missed parts.
Thanks as always
David
Oh, well another birthday has come and gone. Lost a few more grey cells. Having to read again all of the posts to figure out what I have forgotten.
I have built the same JK cap Mx you and Vunce are using and plan on placing the bridge outboard. For the current needs of the BB how large of a heatsink for this parts would you guess. Do I need something like the heatsinks on the 4U case in the store or smaller? Would some Wakefields on the Mosfets work? Ballpark is ok. I am still struggling with a case either stereo or monoblocks like Juntin built. Both amp boards are mostly completed except for the missing parts I forgot to order.
I have another cart going on Mouser to cover the missed parts.
Thanks as always
David