Thanks a lot Andrew!
I actually thought of requesting the manufacturer to make secondary windings for a higher current rating than the nominal one in order to somehow lower the overall secondary resistance. Is there any other concern that I am missing here except the added resistance?
I plan to make all the transformer windings connecting to a terminal right near the transformer with short leads and perform switching there as well.
Regards,
Oleg
I actually thought of requesting the manufacturer to make secondary windings for a higher current rating than the nominal one in order to somehow lower the overall secondary resistance. Is there any other concern that I am missing here except the added resistance?
I plan to make all the transformer windings connecting to a terminal right near the transformer with short leads and perform switching there as well.
Regards,
Oleg
Just noticed this line:
This sounds even more reasonable to me and probably varying the primary turns is even simpler because it eliminates the need to have 4 extra secondaries... Great idea!
Thanks a lot Andrew!
This sounds even more reasonable to me and probably varying the primary turns is even simpler because it eliminates the need to have 4 extra secondaries... Great idea!
Thanks a lot Andrew!
FWIW - Both of the setups shown in post #1657 have safety/earth ground connections, neither couples the grounds. I believe Dario explained when that might be necessary in some previous posts.
The monoblocks have 300VA transformers and the DM uses 200VAs. I have had excellent results (little or no apparent lack of basic power/headroom) all the way down to those 125/24 VA ApexJr surplus transformers. However - all my speakers are nominally 8 ohm.
Curious - Is the quad secondary you mention a toroid or an R-core?
Last edited:
No, splitting has been described twice before.
Just unwrap insulation to expose the secondaries opposite the lead outs. I apply three turns of sticky tape either side of the "working area" to secure all the windings until the job is finished.
Scrape off a tiny bit of enamel. They usually use different colours for bifillar windings.
Measure the voltage from each end to exposed point. Adjust one turn to left or right depending on voltage measured until you find the exact centre.
Snip that winding. Attach flexible lead outs.
Repeat for the other winding.
Thoroughly insulate the soldered connections. Thoroughly insulate the windings. Insulate the scraped points.
The odd thing is that you now have leadouts at diametrically opposite sides of the toroid, bad for loop area.
Just unwrap insulation to expose the secondaries opposite the lead outs. I apply three turns of sticky tape either side of the "working area" to secure all the windings until the job is finished.
Scrape off a tiny bit of enamel. They usually use different colours for bifillar windings.
Measure the voltage from each end to exposed point. Adjust one turn to left or right depending on voltage measured until you find the exact centre.
Snip that winding. Attach flexible lead outs.
Repeat for the other winding.
Thoroughly insulate the soldered connections. Thoroughly insulate the windings. Insulate the scraped points.
The odd thing is that you now have leadouts at diametrically opposite sides of the toroid, bad for loop area.
Last edited:
Yes, a 20Aac transformer recovered from a jukebox amplifier was not much good to me.
But makes an excellent quad 5Aac.
As an aside.
That commercial jukebox amplifier had multiple steel panels with plastic corners to form a "cheap" Chassis.
Every panel had a welded threaded connector.
All six panels were wired together for proper PE protection. Thorough !
Jukebox manufacturers must know something of the habits of their (sometimes drunken) users
But makes an excellent quad 5Aac.
As an aside.
That commercial jukebox amplifier had multiple steel panels with plastic corners to form a "cheap" Chassis.
Every panel had a welded threaded connector.
All six panels were wired together for proper PE protection. Thorough !
Jukebox manufacturers must know something of the habits of their (sometimes drunken) users
Last edited:
to bcmbob.
I don't think it will be really spectacular or unusual
I plan to use 2U "pesante dissipante" cases from modushop.biz... I'll post pictures when done. Now I am at the soldering stage, just surface mounted parts are done. I would probably also change LM3886TF to LM3886T version for better heat dissipation and use insulating pads.
Oleg
I don't think it will be really spectacular or unusual
I plan to use 2U "pesante dissipante" cases from modushop.biz... I'll post pictures when done. Now I am at the soldering stage, just surface mounted parts are done. I would probably also change LM3886TF to LM3886T version for better heat dissipation and use insulating pads.Oleg
You know what they say: "If it ain't broke - don't fix it"
Again - in the dual mono in the earlier post, as single PC CPU cooler and a small 1/4" plate easily handles the heat from two modules. Though, your amp - your call .....
Attachments
Last edited:
BOM update
now the suggested part for R13 is the KOA CF1/2 already present as 'industrial' part.
I still slightly prefer the Rikens in that role (fuller and sweeter) but, apart price increase and limited availability, it's a bit colored, the carbon film KOA is more neutral and a bit more detailed, a more universal choice.
After months of listening I can't suggest the Caddock MK132 in that role, it has a good timbre, wonderful soundstage and clarity but it's not musical at all, too much impulsive and nervous, considering also the price it's a no-no.
Also, for C13 I no longer recommend the K71-4 as alternates, too lean.
now the suggested part for R13 is the KOA CF1/2 already present as 'industrial' part.
I still slightly prefer the Rikens in that role (fuller and sweeter) but, apart price increase and limited availability, it's a bit colored, the carbon film KOA is more neutral and a bit more detailed, a more universal choice.
After months of listening I can't suggest the Caddock MK132 in that role, it has a good timbre, wonderful soundstage and clarity but it's not musical at all, too much impulsive and nervous, considering also the price it's a no-no.
Also, for C13 I no longer recommend the K71-4 as alternates, too lean.
Last edited:
Hi Dario,
I understand. The K71-4 still sounds pretty good in some systems, but I get what you mean. In addition, the K71-4 are becoming less available and, sometimes, more expensive.
I'm just curious, what do you now recommend instead, the basic BOM Vishay? Or the medium jump up in price to the Mundorf Supreme?
Jac
Hi Jac,
they can be fine for HF in an active crossovered system, not for a full range one, IMHO.
it depends, if price is an high concern the Vishays will do, otherwise the Supremes are my first recommendation.
Turn it up and Listen
Hey all,
I've just gotten back from a nearly month long road trip with only my headphones for musical company. I had forgotten how great the FE sound. I guess I get used to the sound and become unaware of what a great thing they really are.
Now I'm all fired up to play with audio again. Thanks to Mauro, Dario, and all the others who moved the My_Ref amp forward. It's been a fun journey so far.
Jac
Hey all,
I've just gotten back from a nearly month long road trip with only my headphones for musical company. I had forgotten how great the FE sound. I guess I get used to the sound and become unaware of what a great thing they really are.
Now I'm all fired up to play with audio again. Thanks to Mauro, Dario, and all the others who moved the My_Ref amp forward. It's been a fun journey so far.
Jac
CAp Character
They can work pretty well for HF in a passive crossover too. I'm currently using a pair of 10 uF K71-4 plus two 1 uF K71-4 all in parallel for 22 uF as part of a tweeter crossover. They beat out Solen, Obbligato Gold, and Audyn Plus in that position. Of course, in big caps like that, the really good caps get really pricey, so I haven't tried anything truly premium.
I ordered some Supremes and Silver Oils. I hope to do a little evaluation of C13 caps to see what works best for me, now that I have finished my crossover update.
They can work pretty well for HF in a passive crossover too. I'm currently using a pair of 10 uF K71-4 plus two 1 uF K71-4 all in parallel for 22 uF as part of a tweeter crossover. They beat out Solen, Obbligato Gold, and Audyn Plus in that position. Of course, in big caps like that, the really good caps get really pricey, so I haven't tried anything truly premium.
I ordered some Supremes and Silver Oils. I hope to do a little evaluation of C13 caps to see what works best for me, now that I have finished my crossover update.
Dario, do you mean KOA at R13 or R10? I don't remember anyone ever trying Riken at R13, but we have tried Takman REX CF's there and they seemed fine. Does the KOA have magnetic end caps? Most of them do. Boo to magnetic parts.
Anyone want a pair of 390 ohm Rikens for R10? One used with trimmed leads, one brand new. Pay the postage plus a buck each, and they're yours. I think the Caddock MK132's sound excellent at R10, with depth and clarity. Not sure what "impulsive and nervous" means, but I think I don't hear that. I am not done evaluating them yet, but naked Z-foil Vishays might be even better, just a little smoother.
Peace,
Tom E
Anyone want a pair of 390 ohm Rikens for R10? One used with trimmed leads, one brand new. Pay the postage plus a buck each, and they're yours. I think the Caddock MK132's sound excellent at R10, with depth and clarity. Not sure what "impulsive and nervous" means, but I think I don't hear that. I am not done evaluating them yet, but naked Z-foil Vishays might be even better, just a little smoother.
Peace,
Tom E
Ooops.. you're right... I meant R10.
KOA CF sound good also in R13 (they're the suggested part in the 'On a budget' BOM) but MK132 are way better, simply perfect in that position.
Yes, they do have magnetic endcaps, nevertheless they're the best sounding industrial carbon films I've found.
The only non-magnetic counterpart are Takmans REX but are too much colored IMHO.
At last my amp is singing
I've had a few problems with one channel, a solder bridge under the lm318, but reading the previous pages of this thread i found the solution.
I wish to thank all of you guys, and especially Dario, for his work and for sharing his experiences with us.
A few pictures of my build...
I've had a few problems with one channel, a solder bridge under the lm318, but reading the previous pages of this thread i found the solution.
I wish to thank all of you guys, and especially Dario, for his work and for sharing his experiences with us.
A few pictures of my build...