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ZMA - comperhensive upgrade complete (Read 27133 times)
Archie
Seasoned Member
Posts: 2731
Re: ZMA - comperhensive upgrade complete
Reply #150 -
01/16/21 at 16:56:55
Electrical Engineering is so far out of my league that I can't even see it but still 9 amps is huge! I asked about heat earlier because I thought the KT150s might dissipate more heat than the KT66s but doesn't this extra power get dissipated as heat somehow?
I am going off of memory that the ZMA draws 150W. If 4 amps is correct than its really more like 480W. So this may be more of a question of how Steve measures things vs how you do.
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ZLC
Technics 1200G TT w/ Ortofon Jubilee MC cart
ZMC1
ZP3 (25th A Mods)
ZR2 (25th A Mods)
CSP3 (25th A mods)
ZMA (25th A mods)
Homemade Big Betsy Speakers (F15s)
Silver Cabling
DIY Isolation platforms under amps & TT.
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BAndrade
Seasoned Member
Do it once, do it
right. Repeat for
quality life.
Posts: 156
Re: ZMA - comperhensive upgrade complete
Reply #151 -
01/16/21 at 21:08:27
If the stock ZMA draws 150 watts of power from the wall allowing for a lagging power factor of 0.85 the current draw is about 1.5 amps from the wall.
The recommended fuse size for most electrical equipment can vary between 1.25 to 1.5 times the actual current draw of the equipment, some times higher depending of the type of load to prevent nuisance blows. Try putting in a fuse that is even a generous double the said above current which is based on 150W say a 3 amp fuse in this case and see if it blows. In my experience when mine was still stock specs., 6.3 amp fuses were blowing and so I had to go higher at that time. I believe in most other cases a 6.3 amp fuse is fine.
To measure the current draw I used a clamp current meter on a discarded power cable with live, neutral and ground cables separated from each other.
After 30 minutes of operation it probably draws about 7 or 8 amps. I have not checked it at this stage and do not intend to experiment further as it is not important from me what ever it is since I am using a solid wire in place of a fuse and it will be time wasted fabricating a wire again.
Sure additional heat is dissipated from KT150 compared to the KTs rated below it. But as you can see from the attached picture taken a few minutes ago after a couple of months with KT150s usage, the meters and the surroundings are as good as new, no heat related issues.
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IMG_20210116_161623_resized_20210116_041700469.gif
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Archie
Seasoned Member
Posts: 2731
Re: ZMA - comperhensive upgrade complete
Reply #152 -
01/16/21 at 22:37:12
I never doubted your word that heat wasn't an issue for you. I am just amazed at the current draw. The surge is either much more than 2X or the power is much higher than advertised. I think my biggest concern is what it costs me to leave my amps on all day given the price of electricity!
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ZLC
Technics 1200G TT w/ Ortofon Jubilee MC cart
ZMC1
ZP3 (25th A Mods)
ZR2 (25th A Mods)
CSP3 (25th A mods)
ZMA (25th A mods)
Homemade Big Betsy Speakers (F15s)
Silver Cabling
DIY Isolation platforms under amps & TT.
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BAndrade
Seasoned Member
Do it once, do it
right. Repeat for
quality life.
Posts: 156
Re: ZMA - comperhensive upgrade complete
Reply #153 -
01/17/21 at 02:31:37
I too am conscious of its electricity consumption. No sooner I am done listening I turn it off.
Besides I have built it to a level with money and effort such that it is irreplaceable for me no matter what the price of another amp. The outcome is so good that I want it to last 25 years or more.
Heat multiplied by the duration of heat application is the worst and only enemy of capacitor and transformer life span. That is why as a small mitigating measure I made vent holes on the bottom board of the casing to somewhat at least induce natural ventilation from the bottom holes to the large cap circumferential gap. Small outcome but better than fully sealed I think.
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Archie
Seasoned Member
Posts: 2731
Re: ZMA - comperhensive upgrade complete
Reply #154 -
01/17/21 at 06:40:20
My ZMA is in a corner so I mounted a computer box type fan behind it. It definitely helps cool things off and is very quiet.
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ZLC
Technics 1200G TT w/ Ortofon Jubilee MC cart
ZMC1
ZP3 (25th A Mods)
ZR2 (25th A Mods)
CSP3 (25th A mods)
ZMA (25th A mods)
Homemade Big Betsy Speakers (F15s)
Silver Cabling
DIY Isolation platforms under amps & TT.
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Stefan
Seasoned Member
Posts: 119
Re: ZMA - comperhensive upgrade complete
Reply #155 -
01/23/21 at 00:53:59
Thanks for sharing all of this! This is very cool!
I would also be interested in a Decware amp that comes with KT150's and would offer 60-80W, in case you are listening (or reading this) Steve ;)
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- Stefan
---------------------
Rega rp6, Lounge Audio phono pre-amp, Lonely Raven PC, T+A DAC 8 DSD, ZBIT, ZROCK2+25th, SE84UFO25, Torii IV, Denon AVC-1SE, Infinity IRS Beta, Tannoy Cheviot, ERRx, Tiny Radials, Woo WA-3, Sennheiser HD800S
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Archie
Seasoned Member
Posts: 2731
Re: ZMA - comperhensive upgrade complete
Reply #156 -
01/23/21 at 07:11:32
Mono-blocks!
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ZLC
Technics 1200G TT w/ Ortofon Jubilee MC cart
ZMC1
ZP3 (25th A Mods)
ZR2 (25th A Mods)
CSP3 (25th A mods)
ZMA (25th A mods)
Homemade Big Betsy Speakers (F15s)
Silver Cabling
DIY Isolation platforms under amps & TT.
IP Logged
BAndrade
Seasoned Member
Do it once, do it
right. Repeat for
quality life.
Posts: 156
Re: ZMA - comperhensive upgrade complete
Reply #157 -
01/23/21 at 14:20:25
I am so impressed with what excess power reserve provided by the amp can do for the same set of speakers that I have decide now to increase it further.
Having this power reserve to more easily drive the speaker drivers is analogous to driving a car weighing say 2 tons (about normal weight of a midsized car) with say a 500hp engine versus another similarly weighing 2 ton car driven by a 250hp engine. The latter will be sluggish, less responsive compared to the former. You do not need 500hp to propel the car all the time but if a change of speed (dynamism) is what the moment dictates the higher power car will respond better in that moment. Similarly for music as it is constantly varying. Conversely one could reduce the weight of the car to increase the power to weight ratio if engine power increase is not feasible.
Since my ZMA has reached its limits in terms of power increase capability I decided to replace 4 of the drivers in my 5 way PSB T3 speakers with Lii audio's premium 7" full range high efficiency drivers. This will also enable me to remove four of the power guzzling, signal corrupting and more importantly signal coloring crossovers in addition to the 89db drivers. Multiple gains. Just 2 of these full range drivers will cover the work of 4 power hungry drivers and crossovers giving me in theory (at this point) more audio output and speed. I'll just leave the lone PSB driver (woofer) and it's crossover that covers the range from 24Hz to 60Hz as the Lii audio full range drivers specs show the need for help is needed in that area.
As always I try to do things that can be easily reversed if it does not work out. It's the same in this case.
I am excited about this. This is not my original idea. I must again give Steve credit for it. He has far more audio related experience and importantly shares it. Through his writings he unknowingly instilled this idea in my mind.
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Archie
Seasoned Member
Posts: 2731
Re: ZMA - comperhensive upgrade complete
Reply #158 -
01/23/21 at 19:39:15
That's a great idea. Going to higher efficiency drivers "doubled or tripled" the power of my ZMA.
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ZLC
Technics 1200G TT w/ Ortofon Jubilee MC cart
ZMC1
ZP3 (25th A Mods)
ZR2 (25th A Mods)
CSP3 (25th A mods)
ZMA (25th A mods)
Homemade Big Betsy Speakers (F15s)
Silver Cabling
DIY Isolation platforms under amps & TT.
IP Logged
BAndrade
Seasoned Member
Do it once, do it
right. Repeat for
quality life.
Posts: 156
Re: ZMA - comperhensive upgrade complete
Reply #159 -
01/23/21 at 21:03:09
I second Stefan's request to Steve for a KT150 amp preferably in a single chassis to keep build cost down and the cost for the end user as well. Should cost about 20% more than a ZMA (because Steve will have more bargaining power with suppliers than me) and at that price it would be a steal for what you get from an audio uplift stand point compared to a ZMA.
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Carlsbad
Seasoned Member
Posts: 202
Re: ZMA - comperhensive upgrade complete
Reply #160 -
07/24/22 at 02:24:03
Just found this thread and read a lot of it but not all of it yet. I'm a serial upgrader but BAndrade makes me look like a rookie. We do think a lot alike. I've been posting for years that instead of buying fancy fuses, replace them with copper bars. And I fully agree with his thoughts on burn in. No burn in on cables. Short burn in on electronics.
I hope he is still around. I'd love to hear an update. But people like him with a huge dose of OCD don't sit around. I'm sure he is putting his talents into another project by now.
I'm thinking my next mod, which should be easy, would be to upgrade the simple diode rectiiers...but it doesn't appear that simple. And adding more capacitance seems like an easy and great change. I'd like to replace the input transformers and I even looked up the exact ones he purchased.
Jerry
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Decware SE84UFO w/20th mods
Grimm MU1 Streamer
Lampizator Golden Gate 3 DAC
Tekton Encore Speakers
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BAndrade
Seasoned Member
Do it once, do it
right. Repeat for
quality life.
Posts: 156
Re: ZMA - comperhensive upgrade complete
Reply #161 -
07/24/22 at 15:37:34
Hi folks, have not been here for a while as other stuff in life is keeping me busy.
For those wondering, the modified ZMA is still regaling us driven by KT150's on full range speakers and solid high purity copper wires in place of the fuse.
I have not worked on it since my last post here as I have reached a point of substantially diminishing returns for this design of the amp and more importantly am very satisfied with the outcome. Besides all the lessons learned here is another one.
If I were to do it again I would probably build one from scratch based on the ZMAs simple straight forward no nonsense design instead of modifying the stock one. As it turned out I needed a slightly larger enclosure and another enclosure dedicated to power supply filtering that plugs in to the main enclosure
Cheers,
BAndrade
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Carlsbad
Seasoned Member
Posts: 202
Re: ZMA - comperhensive upgrade complete
Reply #162 -
07/24/22 at 21:34:44
BAndrade
Thanks for coming back and giving us an update.
I'll probably be doing some of your upgrades (although I do have a custom amp being made by a fellow enthusiast).
First I looked at was the diodes. Seems simple, replace a 50c diode with something better. but I didn't find anything better that was a straightforward replacement--probably why Steve chose these.
Can you comment on the diodes you chose? I found some negative comments about using the diodes you used (Schottky Ultra Fast 10A 1200V) related to leakage current and speed. You seem to have done your research so I'm guessing you chose them carefully.
I have to say your documentation of your mods online was very unselfish and a great resource for us all. thank you very much.
Jerry
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Decware SE84UFO w/20th mods
Grimm MU1 Streamer
Lampizator Golden Gate 3 DAC
Tekton Encore Speakers
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Carlsbad
Seasoned Member
Posts: 202
Re: ZMA - comperhensive upgrade complete
Reply #163 -
07/24/22 at 22:03:32
New "fuse" installed. Immediately awesome. Fullness and clarity is my first description. The link will expire eventually so if the photo doesn't work, the new fuse is 6n pure copper.
https://share.icloud.com/photos/0adOlhLWHkPvnbunTlmCq4V7w
after an hour listening to it, I can say that the fuse isn't going back in for listening. I will want to put it in while swapping tubes--especailly to NOS tubes or used tubes that could be suspect.
I'm toying with the idea of putting a toggle switch to bypass the fuse so I can switch back and forth quickly.
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Decware SE84UFO w/20th mods
Grimm MU1 Streamer
Lampizator Golden Gate 3 DAC
Tekton Encore Speakers
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BAndrade
Seasoned Member
Do it once, do it
right. Repeat for
quality life.
Posts: 156
Re: ZMA - comperhensive upgrade complete
Reply #164 -
07/25/22 at 01:46:01
Jerry to your question on Schottky Ultra Fast diodes 10A 1200V that I used w.r.t. leakage current and speed.
It was a while ago so almost forgot the subtle reasoning behind this move. But I tried to recall and here it is.
As you know any type change will have it's advantages and disadvantages. I mitigated the higher reverse leakage current associated with Schottky diodes by installing substantially larger rated ones (10A 1200V) than what is actually drawn by the ZMA. As reverse leakage increases exponentially with the temperature of the diode while in use by using an overrated diode the temperature should not go high, so substantially minimizing the reverse losses. I also made holes on the bottom of the casing for air flow by convection (not much, but better than being sealed tight) not only for this but other components as well.
Also principally for everything done on the amp for me it was not about losses or efficiency (power consumption) but the better performance. In this case the Schottky diodes due to lower forward voltage losses, the draw to the Schottky Ultra Fast diodes was their fast switching and low forward voltage drop.
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Carlsbad
Seasoned Member
Posts: 202
Re: ZMA - comperhensive upgrade complete
Reply #165 -
07/25/22 at 12:31:03
Thanks BAndrade. I'll get them on order. --Jerry
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Decware SE84UFO w/20th mods
Grimm MU1 Streamer
Lampizator Golden Gate 3 DAC
Tekton Encore Speakers
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