hi protos,
You did a shareable relationship.
My_ref not doesn't want be better than Aleph or Tripath...
A suggestion that is able give is to try it with a 24+24vac trafo, to have at least +-35Vdc. (my is 25+25Vac 225VA)
The load to 4ohm is not a problem, the circuit is predisposed.
I have planed the circuit because work well with +-35 to +-40Vdc, and with toroidal trafo from min. 220VA
I Share the Brian words:
Even Aleph with a too low voltage and with too little trafo perhaps go well.
Better behaviour always the comparisons with an "ideal setup".
ciao
Mauro
You did a shareable relationship.
My_ref not doesn't want be better than Aleph or Tripath...
A suggestion that is able give is to try it with a 24+24vac trafo, to have at least +-35Vdc. (my is 25+25Vac 225VA)
The load to 4ohm is not a problem, the circuit is predisposed.
I have planed the circuit because work well with +-35 to +-40Vdc, and with toroidal trafo from min. 220VA
I Share the Brian words:
Even Aleph with a too low voltage and with too little trafo perhaps go well.
Better behaviour always the comparisons with an "ideal setup".
ciao
Mauro
Well , I call the shots the way I see them in all sincerity.I have no intention of spoiling anybody´s fun and of course its all my personal opinion, in my set up, in my listening room.But I think commenting negatively can also be helpful.
The trafo might not be huge but it should handle a 2x20w output quite well.It did not buzz or heat up at all which would be a sign that it was working hard.
I remember a post a while back where you said your trafo must be around 120VA?
Anyway I might give it another shot using two 220VA /12Vtrafos connected in series.That would give 440VA and 24V.
Personally I don´t think it will make a huge difference at low -medium levels at least.
But let us see.....
The trafo might not be huge but it should handle a 2x20w output quite well.It did not buzz or heat up at all which would be a sign that it was working hard.
I remember a post a while back where you said your trafo must be around 120VA?
Anyway I might give it another shot using two 220VA /12Vtrafos connected in series.That would give 440VA and 24V.
Personally I don´t think it will make a huge difference at low -medium levels at least.
But let us see.....
Hi Protos.
I can confirm what Russ Brian and Mauro just said.
both the tripath (i have build three of these) and the My_ref needs the same power supply.
34-40v on the rails. and a min of 220va or more trafo. it will them be interreting to see the difference.
once you have done that you will have a good comparison. from experience the 2022 never made the grade. the 2350 were 10x better and the my-ref is marginally better than the 2350, but can't supply the power.
but i am also interrested to see the diffrence in sound quality between the twisted pear board and the one that i have done. Maybe not much in it but still interresting
I can confirm what Russ Brian and Mauro just said.
both the tripath (i have build three of these) and the My_ref needs the same power supply.
34-40v on the rails. and a min of 220va or more trafo. it will them be interreting to see the difference.
once you have done that you will have a good comparison. from experience the 2022 never made the grade. the 2350 were 10x better and the my-ref is marginally better than the 2350, but can't supply the power.
but i am also interrested to see the diffrence in sound quality between the twisted pear board and the one that i have done. Maybe not much in it but still interresting
Protos,
Brian is right. In the past with my gainclones I was playing a lot with the trafos. The most crappy sounding setup was with a 160VA / 17V AC sec EI
transformer. The same amp sounds in another class with a >300 VA big EI one, 24 V AC. With the smaller transf. it sounded closed in, grainy, rough.
With the big one it sounds huge, lushy, shiny, warm. Ok, these are my personal experiences, but the difference is great and real. Also the diodes..
Then, while on the tripath amp You can select the settings for high level Ps / low level Ps [30V being the threshold] in the My-ref you are simply underbiasing the power supply zener for the LM318 by ~10 mA when you feed it with 28V [initial, which with that tiny transformer crashes well below 20V soon].
Then, it's not true that a dual mono supply would just give the same benefit for the Tripath amp as well - you CAN go dual mono in a second with the My-ref, and you CAN'T do it with the Tripath!
Well, apart from this it's very refreshing to have an independent opinion and You might be even right - but please rectify these problems first..
By the way I will cross check You soon - I also have both, though not working yet.
Ciao, George
Brian is right. In the past with my gainclones I was playing a lot with the trafos. The most crappy sounding setup was with a 160VA / 17V AC sec EI
transformer. The same amp sounds in another class with a >300 VA big EI one, 24 V AC. With the smaller transf. it sounded closed in, grainy, rough.
With the big one it sounds huge, lushy, shiny, warm. Ok, these are my personal experiences, but the difference is great and real. Also the diodes..
Then, while on the tripath amp You can select the settings for high level Ps / low level Ps [30V being the threshold] in the My-ref you are simply underbiasing the power supply zener for the LM318 by ~10 mA when you feed it with 28V [initial, which with that tiny transformer crashes well below 20V soon].
Then, it's not true that a dual mono supply would just give the same benefit for the Tripath amp as well - you CAN go dual mono in a second with the My-ref, and you CAN'T do it with the Tripath!
Well, apart from this it's very refreshing to have an independent opinion and You might be even right - but please rectify these problems first..
By the way I will cross check You soon - I also have both, though not working yet.
Ciao, George
The aleph x is a true class a design as you know which means it is drawing as much or more quiescent current at idle than when playing at full volume.Therefore trafos have to be rated as if it is a class ab design playing at full output.
With class ab designs one can be a little bit more flexible depending on how difficult the load or how high the output is likely to be because the current drawn will likely be much less than a class a.
I would say the my-ref is much much more efficient than the aleph x which is why I thought a smaller trafo would be acceptable for up to medium listening levels.
With class ab designs one can be a little bit more flexible depending on how difficult the load or how high the output is likely to be because the current drawn will likely be much less than a class a.
I would say the my-ref is much much more efficient than the aleph x which is why I thought a smaller trafo would be acceptable for up to medium listening levels.
Joseph K said:
That was one of the things that I had pondered regarding PS voltage at 27v.The matter of the biasing the ps of the lm 318 etc.But Russ seemed to think that there was no problem and he had tried 28V as well.I don´t know if the zeners are underbiased and how much or little is critical in this case for their correct function.
Anyway I accept your suggestions and will try the bigger trafos .
I agree with all the last interventions.
Tanks for you "Zener underbias concept" explain, George, it is a thing that I wants say...
Andypairo, if you have here trafo, is too little.
Protos,
The trafo sizing not is only a "class propriety" of power amp.
If a max. output power (amp) is "x" the optimize trafo is "x + PSUpower dissipate + overkill".
A 250VA, 25+25Vac trafo out = 5Arms max current supply, indifferently if to continue or temporary regime...
ciao
Mauro
Tanks for you "Zener underbias concept" explain, George, it is a thing that I wants say...
Andypairo, if you have here trafo, is too little.
Protos,
The trafo sizing not is only a "class propriety" of power amp.
If a max. output power (amp) is "x" the optimize trafo is "x + PSUpower dissipate + overkill".
A 250VA, 25+25Vac trafo out = 5Arms max current supply, indifferently if to continue or temporary regime...
ciao
Mauro
BrianDonegan said:
Don´t remind me!I have lost 4 out of 6-7 shipments here the last two months.Including a shure v15 from ebay and many other things.
It is almost a guarantee now that anything not tracked or registered and with a value will not reach me.I still cannot believe it.
As you can see your kits arrived safe and sound.
Hi Protos, I did say 28V rails worked, but I would not ever say they were optimal.
150VA for a single channel is OK, but 150VA for 2 channels is not really enough. I would go no lower than 250-300VA and 400VA is what I use, and in one amp I have 600VA which I know is overkill, but it sounds awesome.
Cheers!
Russ
150VA for a single channel is OK, but 150VA for 2 channels is not really enough. I would go no lower than 250-300VA and 400VA is what I use, and in one amp I have 600VA which I know is overkill, but it sounds awesome.
Cheers!
Russ
Andypairo said:
Ciao Mauro,
I am getting aware that my purposedly-bought150VA encapsulated toroids (2*24V) are maybe on the "small" side, as alternative I have a pair of 2*28V - 250VA... is this better?
Ciao
Andrea
Andrea, which PCBs are you using? For my monobloc PCBs one of those 150VA toroids per channel (300VA system total) should be just fine. I have used such a configuration.
Cheers!
Russ
Just to try to clear up any confusion, there are two implementations of the core circuit.
1) Stereo PCB which should have around 250VA at least as Mauro recommends.
2) Monobloc PCB which can use 120-150VA or more per channel or a single 250VA or more trafo connected to two PCBs for stereo operation.
With the monoblocs to get the best seperation and true monobloc operation two trafos is optimal. One trafo certainly still sounds very good indeed, and is very comparable.
24-25V (48VCT) secondaries are optimal, anything else is a compromise, unless you alter the circuit.
Cheers!
Russ
1) Stereo PCB which should have around 250VA at least as Mauro recommends.
2) Monobloc PCB which can use 120-150VA or more per channel or a single 250VA or more trafo connected to two PCBs for stereo operation.
With the monoblocs to get the best seperation and true monobloc operation two trafos is optimal. One trafo certainly still sounds very good indeed, and is very comparable.
24-25V (48VCT) secondaries are optimal, anything else is a compromise, unless you alter the circuit.
Cheers!
Russ
mauropenasa said:
Andypairo, if you have here trafo, is too little.
ciao
Mauro
I was suspecting so.
Russ White said:
Hi Russ,
I use the stereo board, so, unless I cut some traces on the PCBs to make it dual-mono like I can't use them.
I bought them to make a comparison between RevA and RevC, but it seems I'm screwed
As said before I have also 2 bigger toroids (250VA) but their voltage rating is on the high side (28V+28V) and I noticed that using higher rails makes my heatsinks quite hotter.
Anyway, if heat is the only real drawback I think I can change heatsinks.
Cheers
Andrea
Hi guys, I'm haveing such fun playing with the amp, I basicaly am building it in photoshop (don't ask) so that I can figure out the circuit etc, and have a nice colour guide when my parts arrive some day (lol, ordered the board and the kit parts seperately, I know, wha' a dumbarse).
Anyway for my education, why is there no fuseholders on the PCB? lol they always look so pretty.
Anyway for my education, why is there no fuseholders on the PCB? lol they always look so pretty.
For what it is worth on transformers. I initially built the beta rev C's with the cheap ($7) Parts Express Transformer and it did not sound that great. OK, but not great. Switched to a 330 VA torroid transformer and it sounded great. Have since tried 625VA and 250 VA, all three Avel dual 25V and can't hear any difference among the three.