Finally I did in this way and this evening I had the first run with both channels... fantastic
Unfortunately due to the time it played just for 30 minutes with low power... tomorrow I will have a long run
I have just one problem... I buyed ceramic fuse slow-blow 1.25A (230V)
02151.25MXP Littelfuse | Mouser Italia
but I burned 2 fuse in 20 minutes, just turning on the ampli without music.
Do you know why? Is the 1.25A for one channel?
Just for your information 4 years ago, it seems that I buyed 2 toroid
Block RTE 200/2x24 Trasformatore toroidale 200 VA 4.17 A | Conrad.it
As you can see each one has 200VA of power. So probably I need a fuse of 1.6A, right?
Yes
Hi Pete,
it was a an error, thanks for pointing it out.
Just fixed the up to 1.2 BOM.
This is my goal.
Oops, too late, sorryFinally I did in this way and this evening I had the first run with both channels... fantastic
Unfortunately due to the time it played just for 30 minutes with low power... tomorrow I will have a long run
Yes, and no.
With more than 300VA you would need a soft start circuit to use the appropriate fuse.
What blows fuses is transformers' inrush current so, without using soft start you will need an higher rating but have a small added risk.
BTW 1.24A is too much conservative, in fact for my 2x120VA I'm using 1.6A fuses (which will be the new recommended value for up to 2x160VA)
In you case you will need 2A ones or a soft start circuit.
More is involved than you think.
When I put together my first My_Ref monoblocks 2 amp medium blo ceramics were installed. Checked power up, dc offsets, music even. Let run for a couple hours to be certain. Cycled power a few times.
Installed in system, went to play music and both were dead. Fuses blew on power up.
Only difference was changed from 18 ga power cords to 14 ga. The beefier power cords passed higher inrush current and smoked the fuses. First power up on both amps. Installed 3 amp medium blo.
Do not know if inrush current correlates to dynamics. But should.
When I put together my first My_Ref monoblocks 2 amp medium blo ceramics were installed. Checked power up, dc offsets, music even. Let run for a couple hours to be certain. Cycled power a few times.
Installed in system, went to play music and both were dead. Fuses blew on power up.
Only difference was changed from 18 ga power cords to 14 ga. The beefier power cords passed higher inrush current and smoked the fuses. First power up on both amps. Installed 3 amp medium blo.
Do not know if inrush current correlates to dynamics. But should.
No problem... I was quite sure to understand well
Even if it is clear which are actors involved here, I have some doubts about the scope of the fuse.
My toroid has a built in fuse for temperature protection. So I think that the scope of another fuse is to protect the lm3886.
But the ampli is able to drain (in my case 54W on 6ohm) max 3A for each channel. It means a max current on the primary of 1,25A. If I put a fuse of 2A, the protection is unuseful for LM3886. Isn't it?
Probably as suggested by Dario, the best solution is a soft start circuit.
Finally I did in this way and this evening I had the first run with both channels... fantastic
Unfortunately due to the time it played just for 30 minutes with low power... tomorrow I will have a long run
So, I did a run of 3h yesterday and 2h today.
I played heavy metal, rock, pop, classic music, dance '90...
WOW! The result is always good, in any condition...
my ears don't hear so well anymore, but I have heard forgotten sounds...
And I'm using less 10% of volume...
Probably the only defect is low bass, but I'm quite sure that is due to my DIY speakers
Jac: I know this may be a completely naive thought and violate some "keep the signal path as short as possible" rule but maybe the concept of modular design should be approached with these boards. The base PCB could be the attachment point for development modules so one wouldn’t have to take out the whole board from the case each time if one wanted to say...change the op-amps and their respective changes in respective supporting SMDs or changing the R3, C30 & C32 components or using z-foils instead of normal resistors, etc. This way the changes are made in the modules instead of having to rebuild an entirely new set of boards with all new parts...we could even give them names like "the Joseph K opamp module or the Lehmanhill capacitor & R3 module, etc....;>)
Just my two cents (or nonsense)...
Pete
Just my two cents (or nonsense)...
Pete
@Stream, Good suggestion. Would others be willing to post photos of your FE and add a few words on the sound?
Pete,
Its not a bad approach at all. xrk971 with the AKSA's Lender preamp thread took a similar approach with daughter boards that gave builders a choice between SMD and through-hole, for example.
That said, by using a low temperature solder/SMD removal solder like Chipquik SMD1 NL and solder wick, I am comfortable removing most SMD and through-hole components. What I have done is use one set of boards as my main system boards and keep another set for experiments. For example, when I started playing with George's opamps, I went through 3 our of 4 opamps on the same boards and got a good comparisonof those opamps. Email me for more discussion on this, if you like.
Jac
Pete,
Its not a bad approach at all. xrk971 with the AKSA's Lender preamp thread took a similar approach with daughter boards that gave builders a choice between SMD and through-hole, for example.
That said, by using a low temperature solder/SMD removal solder like Chipquik SMD1 NL and solder wick, I am comfortable removing most SMD and through-hole components. What I have done is use one set of boards as my main system boards and keep another set for experiments. For example, when I started playing with George's opamps, I went through 3 our of 4 opamps on the same boards and got a good comparisonof those opamps. Email me for more discussion on this, if you like.
Jac
Jac: I too use both to remove smd & thru-hole components and have grown quite comfortable doing so (switching many an op-amp on my experimental build...a long learning process). But I remember when I started to read this thread when I was just beginning on this journey. Early on one poster commented to Dario that they didn’t want to deal with tiny SMD parts (granted the ones we use are giant compared to other boards I’ve seen) and therefore may not want to build one of the FE versions (I understand the electronics concepts of going the SMD route that Dario took) nor did they want to pay the extra of having someone place all the SMDs for them.
I’m just trying to think how we could bring new folk into the cult here ;>) so to speak.
Pete
I’m just trying to think how we could bring new folk into the cult here ;>) so to speak.
Pete
I'd be interested in trying out this amplifier as I looks to be a nice design. Would be nice if people posted some video's of their amplifiers, perhaps even sound clips with these amplifiers which are in members personal systems, given some who have good quality mic setups for quality sound clips that is.
Interesting. I've found I have a pair of 250VA... A grand total of 500VA if I decide to opt for them (hand built ones from an Italian factory). Should I use a soft start too, u think? I have a pair of these , one still to be built.
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Alas, I don't have a way of recording at any quality.
I don't know if it helps, but I built a tube voltage stage (Impasse by SY) with a Pass F4 current stage and I clearly prefer the Fremen amp with premium components. The Impasse even has $350 in just 2 tubes.
How about guys? Does anybody have a good recording or other way to help him out understanding how it sounds?
Better than sounds clips is the measurements on the first post of the Group Buy. This is the indicator of the delivered Lund quality.
The noise floor is below most amplifiers. Look up tests, Stereophile usually tests all products they review with a SOTA AP analyzer. Even 20K amplifiers do not deliver a noise floor as low as the FE.
Recorded clips will never catch the “sound” of these amplifiers. The source quality, loudspeaker response, and microphone used will color the sound more than the amplifier.
The noise floor is below most amplifiers. Look up tests, Stereophile usually tests all products they review with a SOTA AP analyzer. Even 20K amplifiers do not deliver a noise floor as low as the FE.
Recorded clips will never catch the “sound” of these amplifiers. The source quality, loudspeaker response, and microphone used will color the sound more than the amplifier.
Instead to use something ready, I preferred to project it by myself. So I dimensioned all components for the specific use case.
I realized the attached circuit. It limits the current on the primary side to max 1,25A. It has already 2 output for 2 trafos.
Attachments
Oh, I couldn't do such thing. I'm just getting a good copycat!
I can't state if DIY audio SoftStart is well calibrated - I got in mfly project just 'cause I needed a momentary pushbutton circuit for DCB1 and master/slave addition + softstart was a nice idea.