As Tom already pointed out the input cap is hardly responsible for the type of sound you're describing.
The old BOM is a good match for most speakers but the peculiar sound signature of Caddocks could be detrimental in some cases, as I recently discovered.
The 1.5 BOM gets rid of Caddocks for most positions apart the output resistor and also the LM3886 decoupling caps are changed from FM/RJH to NCC LXZ.
This combination gives a more neutral and detailed sound, one of the main improvement is about mid range and also bass become less prominent and more controlled..
So I would suggest you to try the new BOM alternative parts, IMHO they could make the difference in your case.
Hi Dario, thank you let me enjoy your project, now i'm close to the end and I need a little help.
I want put a green led in the front pannel, but the voltage I find in the pcb is 1.7, I need at list 2.1V. If i'm not wrong the resistor I have change is r23 but if I consider the 24v of the source, my calculation doesn't mach you value. Maybe i've miss something?
Thank you in advance for your help
Sergio
Inviato dal mio PLK-L01 utilizzando Tapatalk
I want put a green led in the front pannel, but the voltage I find in the pcb is 1.7, I need at list 2.1V. If i'm not wrong the resistor I have change is r23 but if I consider the 24v of the source, my calculation doesn't mach you value. Maybe i've miss something?
Thank you in advance for your help
Sergio
Inviato dal mio PLK-L01 utilizzando Tapatalk
Changing the resistor or even a few caps is not going to change the sound of your amplifier enough to fix the problem you have described. You will be wasting your time and money. What you describe is not the effect of Caddock resistors or FM caps. It is an insult to the original designer of this amplifier, Mauro Penasa, to claim that changing a few parts will make that much difference and turn a bad sounding amp into a good one. Dozens of builders will attest that you can build this amplifier with the cheapest parts available and it will sound better than what you describe.
Please answer the question: in one of the pictures you posted, what are you measuring with your meter that reads -13.4?
Perform a few other simple diagnostic tests to determine that the amplifier is really at fault: different speakers, different preamp direct to MyRef inputs, not through your volume control or whatever that thing is.
Peace,
Tom E
Please answer the question: in one of the pictures you posted, what are you measuring with your meter that reads -13.4?
Perform a few other simple diagnostic tests to determine that the amplifier is really at fault: different speakers, different preamp direct to MyRef inputs, not through your volume control or whatever that thing is.
Peace,
Tom E
You're welcome Sergio 🙂
Don't miss to post your build pics here 😉
Yes, IMHO, you're missing something... 😉
What turns on the led is current, the 2.1V voltage will be the one you will read on the led itself when it conducts.
Have you actually tried to connect the led?
Hi Tom,
Peterma, IMHO, is using hyperboles to better describe his impressions.
He's hearing a tiny imbalance in mid freqs (grey, slightly hard sound) and boost in low freqs which is, IMHO, exactly the sound signature of Caddocks.
Also FMs have problems with mid freqs and a bit sloppy bass, the sum of FMs and Caddocks could give, in certain contexts, the type of sound he's describing.
Such imbalance with his speakers is enough to make him unsatisfied.
I really think that LZX (4€ value) and some cheap KOA MF or even better RLR07 could change the sound enough to make him happy with his FEs.
And trying spending less than 10€ more in parts is better than throwing away 300€ already spent...
I fear then that both me and you, to a lesser extent, insulted Mauro repeatedly 😉
BTW
Tom... you should hear how good are sounding my v1.5 FEs with the updated BOM
I would like to say that I am not saying I don't like this amp, I will just need to tweek it to my preference. I thank everyone's efforts. I am going to change the resistors and see how I go there, and I cant get the LZX here without paying too much for postage.
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Then what does unbalanced midrange and boomy bass mean? You said nothing positive about the amp, so how are we to take your comments? You still haven't answered my question about what you measured at -13.4. 😡 Good luck with your tweaking. It is possible to tune the sound to some extent, but you will not change the basic sound of the amp. I can tell you honestly that it works very well with every speaker I've heard it with: half a dozen types from tiny full-rangers up to $16000 giants. But sometimes an amp just doesn't match with speakers, and there's no saving it.
Dario, we have selected certain premium parts because it improved the sound of an already excellent design. It did not change the sound completely. If an amplifier's sound changes so drastically because of changing a few parts, then it's a bad design. This amp sounds very good even with the cheapest parts, but it sounds amazing with really good parts. I didn't mean to offend you about insulting Mauro. I'm sure he would be very proud to hear any of these improved amps.
Glad you're happy with yet another BOM. I am not interested in changing my amps, but perhaps new builders will enjoy the changes. I see you have put KOA resistors in some places. I do not like those resistors at all. Vishay/Dale are much better, in my opinion. But we have disagreed before, and I still respect your opinions after such extensive testing.
I have installed Jupiter copper/beeswax at C13, and it is the best sound I have ever heard from any amplifier. I reduced the input impedance (R13) so I could use a smaller value cap to save some money. I cannot hear any negative impact. I wonder how Mauro decided on 100k? There are many commercial amps that have a lower input imp. It might be worthwhile to experiment with that.
Peace,
Tom E
Dario, we have selected certain premium parts because it improved the sound of an already excellent design. It did not change the sound completely. If an amplifier's sound changes so drastically because of changing a few parts, then it's a bad design. This amp sounds very good even with the cheapest parts, but it sounds amazing with really good parts. I didn't mean to offend you about insulting Mauro. I'm sure he would be very proud to hear any of these improved amps.
Glad you're happy with yet another BOM. I am not interested in changing my amps, but perhaps new builders will enjoy the changes. I see you have put KOA resistors in some places. I do not like those resistors at all. Vishay/Dale are much better, in my opinion. But we have disagreed before, and I still respect your opinions after such extensive testing.
I have installed Jupiter copper/beeswax at C13, and it is the best sound I have ever heard from any amplifier. I reduced the input impedance (R13) so I could use a smaller value cap to save some money. I cannot hear any negative impact. I wonder how Mauro decided on 100k? There are many commercial amps that have a lower input imp. It might be worthwhile to experiment with that.
Peace,
Tom E
I was teasing you... 😉
You're right, the amp sounds very good even with cheap parts but with the wrong selection could sound bad too...
Mauro don't trust in sound differences between similar resistors and caps, he even refused to consider the possibility that the Susumus could sound better than any other 0.1% thinfilm chip resistor...
The FE previous BOM is a really good sounding one and if the result is perfectly fine for you there's no reason to upgrade.
Nevertheless the updated BOM sounds even better, so whoever is aiming at something better should consider updating their existing boards.
In our hobby a lot of people feels the need to upgrade continuosly, for those the new PCBs sounds better with even lower distortion (from preliminary measurements).
Come back to the updated BOM.
As you know I've never been happy with FMs (Elna RJH was the suggested best part) but they were the best ones available from Mouser.
Now that the (much) better sounding and more neutral NCC LZX are available from Mouser I've been finally able to purge FMs from signal path, on the contrary I've replaced a Nichicon FG with FM where they perform best.
Caddock MK132 are no longer available from Mouser and recent test with other gear (headamps) lead me to experiment again with resistors.
Blue Dales are great sounding resistors so they've replaced the Caddocks with the added benefit of a more balanced and neutral sound.
Working on other projects changed my mind on some parts sound, the updated BOM reflects such changes.
I know you disagree but KOA MF are, IMHO, the best sounding cheap resistors I've found so far.
Interesting but so far I'm perfectly fine with plain Mundorf Supremes.
The 100k value has been selected, I think, to have an universal input that doesn't need an active preamp.
Using an active preamp lowering the input impedance should not be a problem.
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-13.4 is one wire from transformer a mistake posting that, and maybe speaker mismatch
Hi Dario,
Sorry for my noob ignorance, a red led is already soldered on the pcb, that the reason why I have 1.7v.
Thank you very much, I will back soon with the photos.
I have taken out my_refs and put in brian gt and have tonal balance back again, sorry to upset anyone but i just thought i should say something, the only other thing that might or might not matter is that the lm3886 chips in my refs are free samples from TI, do you think that would make a difference?
Peterma,
I don't know what is going on with your My_Ref, but it doesn't sound "normal" at all. I recently rebuilt a Brian GT amp for my niece. I upgraded a few components, but didn't significantly change the sound. I compared those to my My_Ref FE's and don't see a tonal balance difference of any significance between the Brian GT and My_Ref. The main difference is that the My_Ref has far better imaging, has a clearer high end, better detail, and a slightly warmer sound. Of course, my speakers are quite different from yours (Dynaudio drivers that are notoriously lower sensitivity, 2-way).
Anyway, I hope you can find a solution that satisfies you.
Jac
I don't know what is going on with your My_Ref, but it doesn't sound "normal" at all. I recently rebuilt a Brian GT amp for my niece. I upgraded a few components, but didn't significantly change the sound. I compared those to my My_Ref FE's and don't see a tonal balance difference of any significance between the Brian GT and My_Ref. The main difference is that the My_Ref has far better imaging, has a clearer high end, better detail, and a slightly warmer sound. Of course, my speakers are quite different from yours (Dynaudio drivers that are notoriously lower sensitivity, 2-way).
Anyway, I hope you can find a solution that satisfies you.
Jac
Don't worry the build thread is here to help 😉
You're welcome.
When using an external LED the one on board should be removed.
Hi atupi,
Mine are old DIY towers that I built back when Dynaudio was still selling drivers to DIY guys. I have a D-28 tweeter and an Esotec 17W LQ woofer.
Jac
Peterma,
Just musing.
One of the unusual aspects of any current pump amp, such as the My_Ref, is that it uses the impedance of the speaker in the feedback. Often, this is helpful in linearizing the response which was one of the original attractions of this design. Note that the BrianGT amps are conventional voltage source amps.
I mentioned the sensitivity of my Dynaudio drivers. I looked up the test data for my woofers and they ran about 84 dB. My thought is that a lower sensitivity driver with similar impedance may react differently than a high sensitivity driver in a current pump design. I may be wrong. Anyway, this is just one of the many ways that amps and speakers sometime need to match characteristics.
Getting off topic.
You asked about a 3 way crossover. Since you didn't mention the mid-range in your speaker description, I'm guessing that you are currently running it as a two-way. Just curious, what frequency are you currently crossing over? Seems like a big stretch between the SLS 12" and the ribbon tweeter.
I know you asked Dario, but if I may, you can build your own 3-way crossover that is based on the response of the drivers which, IMHO, is better than using a generic crossover.
The link below will get you to a bunch of free software that will let you simulate crossovers (passive, active, and DSP). They can work from relatively simple test measurements or even take the manufacturers published curves and generate a crossover without measuring.
software
Although they may overemphasize diffraction, in my opinion, in their help and descriptions, the tools work well. For the passive crossover, you need Excel to run it.
Of course, if you have lots of energy, you have enough amps to build an active or a DSP 3-way crossover. Maybe use the BrianGT for the woofers, and the My_Ref and tube amps for the mid and tweeter.
Jac
Just musing.
One of the unusual aspects of any current pump amp, such as the My_Ref, is that it uses the impedance of the speaker in the feedback. Often, this is helpful in linearizing the response which was one of the original attractions of this design. Note that the BrianGT amps are conventional voltage source amps.
I mentioned the sensitivity of my Dynaudio drivers. I looked up the test data for my woofers and they ran about 84 dB. My thought is that a lower sensitivity driver with similar impedance may react differently than a high sensitivity driver in a current pump design. I may be wrong. Anyway, this is just one of the many ways that amps and speakers sometime need to match characteristics.
Getting off topic.
You asked about a 3 way crossover. Since you didn't mention the mid-range in your speaker description, I'm guessing that you are currently running it as a two-way. Just curious, what frequency are you currently crossing over? Seems like a big stretch between the SLS 12" and the ribbon tweeter.
I know you asked Dario, but if I may, you can build your own 3-way crossover that is based on the response of the drivers which, IMHO, is better than using a generic crossover.
The link below will get you to a bunch of free software that will let you simulate crossovers (passive, active, and DSP). They can work from relatively simple test measurements or even take the manufacturers published curves and generate a crossover without measuring.
software
Although they may overemphasize diffraction, in my opinion, in their help and descriptions, the tools work well. For the passive crossover, you need Excel to run it.
Of course, if you have lots of energy, you have enough amps to build an active or a DSP 3-way crossover. Maybe use the BrianGT for the woofers, and the My_Ref and tube amps for the mid and tweeter.
Jac
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Hello, I have myref Fremen sixth run , it sounds wonderful with Dynaudio . I have also seventh run and I'm looking for a good set of components for me .
I am using a generic three way crossover from Jaycar, I use this amp for all multimedia, last night my wife was watching TV and said was having trouble hearing the voices and that is the problem the midrange is not prominent enough to balance out the lower and higher frequencies in my system.I know that my drivers are not multidollar but, mid range lacks sensitivity, the bass is amazing and deep shocks me a times it just great,( I know I said before the bass is boomy, i mean just not balanced out with other sounds) treble is nice and smooth. anyhow I will probably shelve my refs for a while I don't have time right now my 4 month old son is sick, I am still a bit disappointed I spent more time and money on this amp than any other, but for those of you are happy, don't let my experience deter anyone from trying them. thanks everyone.
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