Sure. That would in fact be easy, if the modification adds one of (these) to the ACP+. Specifically designed and optimized for a 10K ohm load.
Another way to skin the cat is to install standoffs on the ACP+ PCB and then mount "daughter cards" above. One possible daughter card is shown below, delivering 53.4 volts peak-to-trough. See white legend box at top left.
I suspect that a wizard with sufficient motivation, could build a similar daughter card around Hugh Dean's AKSA-Lender circuit design, and achieve similarly large output swing. The hardest part of the job is to identify them and then find a way to motivate them to work on this project instead of whatever else is in the inbox.
_
Thanks for the suggestion on using Edcor 600:10k to boost output. Nice to see Dreadnought having such a big output swing. I have already run the Aksa Lender at 55v rail to get 50Vpp output. Works like a charm. Looking into making it fit on the M2X format bolt pattern. We also have a stackable daughter board that makes isolated +/-35v from single 18v to 30v input.
Planning on using this for an OPA454 (up to 100vpp) Front End stacked above the DCDC PSU, that can drive up to 70v swings, as configured. Verification PCBs have been ordered. Simply populating only the positive rail of the PSU and reconfiguring the resistors for 55v output could then be used for other single rail front ends.
Planning on using this for an OPA454 (up to 100vpp) Front End stacked above the DCDC PSU, that can drive up to 70v swings, as configured. Verification PCBs have been ordered. Simply populating only the positive rail of the PSU and reconfiguring the resistors for 55v output could then be used for other single rail front ends.
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Full Kit delivered yesterday, just over a week from order date, very impressed. Postmark is from Germany!, not sure if the store has a warehouse there or the courier just routes through there?
Also a Galaxy case from modushop came today less than a week from order date, excellent!!
The best thing is that neither incurred any customs or handling fees.
Well done to the store for putting these kits together it has saved me so much time!
Also a Galaxy case from modushop came today less than a week from order date, excellent!!
The best thing is that neither incurred any customs or handling fees.
Well done to the store for putting these kits together it has saved me so much time!
If i may interrupt this, why would one want a preamp with a 50VPP output? To drive a current amp device? Or planar headphones?
And what would be upstream of this MACP+ (Manly ACP+)?
The "F4" amplifier in the diyAudio Store has a current gain >10000x but a voltage gain of only 0.95x. To get 35 watts RMS output from it (at 8 ohm load), you need to provide an input signal of 49.8 volts peak-to-trough.
The DIY VFET amp announced here in April 2021 and sold in May, is a more recent example. It too has enormous current gain, but its voltage gain is significantly less than 0.95x. Thus it also needs an input signal significantly greater than the more typical 9 volts peak-to-trough.
Especially since this latter VFET amp is a mix-and-match collection of numerous compatible and interchangeable (front end cards) and (output stage cards), members are envisioning future variants with bigger heatsinks, higher supply voltages, and greater output power. Compatibility with existing cards requires these future output stage cards to have a voltage gain no greater than 1.0x, thus the input to those stages needs to be quite large. For beefed-up, higher-rail, higher-output-power variants: very much quite sincerely and extremely large.
The DIY VFET amp announced here in April 2021 and sold in May, is a more recent example. It too has enormous current gain, but its voltage gain is significantly less than 0.95x. Thus it also needs an input signal significantly greater than the more typical 9 volts peak-to-trough.
Especially since this latter VFET amp is a mix-and-match collection of numerous compatible and interchangeable (front end cards) and (output stage cards), members are envisioning future variants with bigger heatsinks, higher supply voltages, and greater output power. Compatibility with existing cards requires these future output stage cards to have a voltage gain no greater than 1.0x, thus the input to those stages needs to be quite large. For beefed-up, higher-rail, higher-output-power variants: very much quite sincerely and extremely large.
I recently bought 2SJ74 BL from UTSource, which informs that the items sold are genuine and can be returned at no extra charge. They were advertised as used Toshiba originals. I received new and fake Chinese transistors. I complained and they didn't even respond. Does anyone know this company?
I'd may come in a bit harsh, and I am sorry, but there is, literally, thousands of posts through this threads mentioning that most offers for the Toshibas will be fake. There is a full thread dedicated to tell people the two or three reliable internet sources for those FETs. The Store now has them as well, which are 100% genuine (new LinearSystems stuff). Also, the store has a very significant disclaimer everywhere about extremely high probability of getting fakes if sourcing of the FETs with vendors claiming to sell originals.
I may understand people trying to find other sources of original parts, but I cannot understand buying 99.9% almost-certified fakes to safe a few bucks, and then flood this threads with attempts to test their devices, proof them fake and then start a fight with the sellers of counterfeits.
Simply buy from the 3 respected sources that are now available, being the very own DIY store a very, very secure source!
I may understand people trying to find other sources of original parts, but I cannot understand buying 99.9% almost-certified fakes to safe a few bucks, and then flood this threads with attempts to test their devices, proof them fake and then start a fight with the sellers of counterfeits.
Simply buy from the 3 respected sources that are now available, being the very own DIY store a very, very secure source!
Several amps, including the F4, as MJ mentioned, have about 0dB voltage gain but provide current gain. Others include the MoFo (11wrms) and the LuFo (39wrms.). To get 39wrms into 8ohms, you need about 50Vpp.
Both the MoFo and LuFo get more output swing then the input voltage rail using stored energy in an inductive load after a follower (the Fo in the name). Here is the max output of LuFo into 8ohms;
So the question was, can the rails of ACP+ be increased to support this?
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Simply buy from the 3 respected sources that are now available, being the very own DIY store a very, very secure source!
Not harsh. Wise words.
Best,
Anand.
Do I need the Keratherm Insulators?
Somewhere in the thousands of posts I read insulators weren't necessary for the J74s but some used conductive grease. That kept me from using the silicon wafers I have on hand but now I see these Keratherm in the diyaudio store.
Should I use the wafers?
Spend another 20 Bucks on the Keratherm?
Get some grease the store blurb says is a pain to use?
Just plug the thing in and listen to it?
Somewhere in the thousands of posts I read insulators weren't necessary for the J74s but some used conductive grease. That kept me from using the silicon wafers I have on hand but now I see these Keratherm in the diyaudio store.
Should I use the wafers?
Spend another 20 Bucks on the Keratherm?
Get some grease the store blurb says is a pain to use?
Just plug the thing in and listen to it?
Just put them face to face and put a shrink tube over them. The close contact and being covered by a shrink tube “blanket” will keep them close enough in temperature. Use grease if you want but I feel it’s not necessary. I would not spend $20 on keratherm for that little 4mmx5mm contact patch! Use RTV silicone if you want even. Here is what mine look like (underneath the blue shrink tube):
Shrink tube blanket?
Not sure what that entails but nothing should impede the job of the heat sinks to sink heat, no?
Also, doesn't the construction of the devices keep current out of the heat sinks?
Is there a risk of sayonara shock from any of the exposed devices? My cat would really like to know!
Completed board:
Not sure what that entails but nothing should impede the job of the heat sinks to sink heat, no?
Also, doesn't the construction of the devices keep current out of the heat sinks?
Is there a risk of sayonara shock from any of the exposed devices? My cat would really like to know!
Completed board:
My cat, sensing it’s an electronic equipment that could potentially expel some heat, will pay no attention to any hazard to herself or the equipment.
I’m building a case, I’m not risking the ACP or my cat!