All Hitachi Lateral Fet amplifier for DIY described by Paul Kemble - Page 17 - diyAudio
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Old 29th October 2012, 04:08 PM   #161
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Join Date: Sep 2005
Hello wahab

You convince me about the ground! To get real picture at the test better to separate the ground (otherwise maybe the bad ground degrade the amplifier performance I will not get real picture)
I would like to ask a favour from you.
Can you mark on the circuit those connection to the ground which you think I should connect separate from the main ground.
I ask these because there will be several type of ground. 2 PS ground, signal ground etc.
Until now I built only one amp use 2 PS.....
Thank you very much!
I can ad one more ground trace outside the one already has, that will increase the size of the PC board less than 1Cm.
Also I can connect the two ground (where) if there need with a 10R resister.

Greetings Gabor
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Old 30th October 2012, 01:10 AM   #162
wahab is offline wahab  Algeria
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Quote:
Originally Posted by gaborbela View Post

You convince me about the ground! To get real picture at the test better to separate the ground (otherwise maybe the bad ground degrade the amplifier performance I will not get real picture)
I would like to ask a favour from you.
Can you mark on the circuit those connection to the ground which you think I should connect separate from the main ground.

Also I can connect the two ground (where) if there need with a 10R resister.

Hi , Gabor

Here a schematic with the separated ground marked "HC ground" ,
there s only three components that use this ground , the zobel
network and the power stage decoupling capacitors.

All other components ground connection will be reunited in a second ground,
including the front end decoupling capacitors.

I ll do you a schematic of the power supply wirings , just tell me what kind
of transformer(s) you are using , either if this is one with all the necessary voltages
or if it s separate transformers for the front end and power stage.

Quote:
Originally Posted by gaborbela View Post

I just try to test the amp now to get some idea of the performance.

I test the amp and after I'll start to upgrade. Even like these I can get some idea about the sound quality.
At the test I'll use only one PS how you advised. If I like what I'll hear I will increase the front end with 10V rail voltage.

I just each one PC board for test! After it will be easy to mode the PC board.
If I like the amp I want min. DALE or PRP resistors, and I'll upgrade the PC board to.
These only a test board, I don't want to mess with PP connection.



You can see that there s a current mirror as VAS load in the schematic below,
wich otherwise is strictly the same as in your PCB for all other parts.

Is it possible that you do your PCB routing such that both versions can use
the same PCB?

The change is very little , only a transistor is added and the two resistors
that enclose this added transistor could simply use some of the current version
VAS current source components holes.


The thing is that the amp behave so much better with a current mirror rather
than with a fixed current source as it allow symetrical and higher slew rate
while stability is better.

Also , it sets a very accurate balancing of the VAS transistors pair currents
and the amp has better linearity overall.

That s quite a lot of things considering that the component count is increased
by only a single transistor....

If you wants to make the best possible amp using this topology , such
an implementation has undoubtly way more impact on the amp quality than upgrading
it with selected components , provided the transistors are the good ones
and the resistors are rated to withstand the voltages , 125dB open loop gain
and induced high NFB will level the components differences , the transistors
linearity being the only remaining factor of importance.
Attached Images
File Type: gif HITACHI FFET MOD5 SCH.gif (19.0 KB, 297 views)
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Old 30th October 2012, 02:27 AM   #163
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Hello wahab

Thank you very much for your help!
I will ad Q9 transistor to the layout. My question do I connect the HC ground with the other ground (with resistor of course)
I usually use a 10R resistor between the normal ground and the signal ground.
Because the speakers power goes from the HC do I take that ground from there?
I think yes because the Zobel network goes to the HC ground to.
About the PS I have 1PC 400-40VAC 800VA transformer(I think these would be under rated) or I use 2PC 39-0-39VAC 600VA transformers. For the front I have to look around what do I have. I think I have 45-0-45V transformer but that is from a power amp (huge size) ] Also I have to share the power transformers with another amplifier Aleph2 clone from Mr. Pass.
I will put the transformers in a separate enclosure and I use military connectors for each transformer to attach to the amplifiers until I get one more like these since right now I have 3PC.
These in case if I'd like both amplifier!!!
For the front end I will get something soon, until that I can test it only from one PS each channel.
I will post tomorrow some picture from the connectors and transformers.
Thank you one more time!
Greetings Gabor

Last edited by gaborbela; 30th October 2012 at 02:34 AM.
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Old 30th October 2012, 08:13 AM   #164
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Default Some capacitor question

Hello wahab

I have some question about the next caps
For C4 16V will be enough?
I want to shave of from the existing ground trace, for the front I do not need 1Cm wide ground...
Another capacitor C5 at Zobel, usually we use 0.1uF. The 22nF it is a mistake or correct.
Size here does not mater because it will be mounted on the speakers terminal.
I did some work on the layout, I have to ad the HC ground and double check all and it will be done.
Right now is not finished!
It is possible to go regulated PS at the front in case I get higher voltage transformer.
These only after I test the amp.
Thank you very much!

Greetings Gabor
Attached Images
File Type: bmp All fet Hitachi amplifier.bmp (80.7 KB, 59 views)

Last edited by gaborbela; 30th October 2012 at 08:22 AM.
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Old 30th October 2012, 10:03 AM   #165
AndrewT is offline AndrewT  Scotland
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I would take both the HC ground and the LC ground back to the Main Audio Ground.

But I would separate the Signal Ground with the attached NFB lower leg from the LC ground with that current reducing resistor & diodes.

C4 with the diodes in place should never see more than 1Vpk even during fault conditions.
Without the diodes C4 can see high voltages depending on which fault ocurrs.

You can use 5V caps, but 16V pre reformed is good insurance. That reforming is essential. Otherwise the cap oxides never properly form.
__________________
regards Andrew T.

Last edited by AndrewT; 30th October 2012 at 10:07 AM.
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Old 30th October 2012, 02:04 PM   #166
wahab is offline wahab  Algeria
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Location: algeria/france
Quote:
Originally Posted by gaborbela View Post
I will ad Q9 transistor to the layout.
Thank you for retaining this modification as not only it allow getting rid of
an annoying limitation that has been pointed from the start of this thread
by Zenmod but also to yield a better performing amp thanks to its use of the
subcircuits that have the best perfs returns and wich are rarely if ever used
all at the same time in amplifiers that borrow this topology.

Quote:
Originally Posted by gaborbela View Post
My question do I connect the HC ground with the other ground (with resistor of course)
Yes , a 1R resistor will be adequate but still , each ground must have
its own wire going to the supply ground star point.

I repost the schematic with the resistor.
All grounds with the earth sign are connected to the LC (Low Current) ground.

The second schematic is the one of the PSU so you understand better
how all theses troubling earths are connected.

Quote:
Originally Posted by gaborbela View Post
Because the speakers power goes from the HC do I take that ground from there?
The speaker ground is to be taken on the PSU ground star point not
from the amp PCB grounds.

Quote:
Originally Posted by gaborbela View Post
I think yes because the Zobel network goes to the HC ground to.
If mounted on the PCB the zobel network ground goes to the HC
(High Current) ground , otherwise if it s mounted near the speaker
connector it can then simply use the speaker ground wire.

Quote:
Originally Posted by gaborbela View Post
About the PS I have 1PC 400-40VAC 800VA transformer(I think these would be under rated)
I guess it is a 2 x 40V AC/800VA transformer , in wich case it s not
underated , quite the contrary , it is overated...

A 500VA transformer is largely enough for 8R speakers and even for 4R
if the amp is not at 100% max power 7/24 so 800VA is powerfull enough
to withstand permanently full power on 4R.

Quote:
Originally Posted by gaborbela View Post
I have some question about the next caps
For C4 16V will be enough?
As pointed by Andrew 16V is largely enough but his 6V figure is not....

Quote:
Originally Posted by gaborbela View Post
Another capacitor C5 at Zobel, usually we use 0.1uF. The 22nF it is a mistake or correct.
22nf should work well enough , i have two amps using three lateral pairs
and one has 22nf while the other is happy with 15nF.

Quote:
Originally Posted by gaborbela View Post
Size here does not mater because it will be mounted on the speakers terminal.
As pointed above , in this case its ground connection can use
either the speaker ground wire or be returned directly to the power
supply ground star point.

Quote:
Originally Posted by gaborbela View Post
It is possible to go regulated PS at the front in case I get higher voltage transformer.
It is possible but not strictly necessary as the amp has high open loop gain ,
hence rejection of the supply noises is operated by the amp inherent
high negative feedback efficently enough that a 47R + 1000uF decoupling
cell for the front end is all what is needed to render a regulated power
supply useless.

On the schematic i did put 220uF , this is the absolute minimal value for
these front end decoupling caps.

I saw that you did parralel them with small MKP/MKT capacitors and it is
a very good thing in respect of the PCB high frequency behaviour.

Hope this will help remove eventual shadowed areas....
Attached Images
File Type: gif HITACHI FFET MOD5 SCH.gif (20.0 KB, 248 views)
File Type: gif PSU SINGLE XFORMER SS MB.gif (10.4 KB, 250 views)

Last edited by wahab; 30th October 2012 at 02:07 PM.
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Old 30th October 2012, 05:45 PM   #167
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[QUOTE=wahab;3221060]I guess it is a 2 x 40V AC/800VA transformer , in wich case it s not
underated , quite the contrary , it is overated...

A 500VA transformer is largely enough for 8R speakers and even for 4R
if the amp is not at 100% max power 7/24 so 800VA is powerfull enough
to withstand permanently full power on 4R.
QUOTE]

Hello
A big thank both of you for the help!
About the transformer what is troubling me.
The Grand Mos use 52V rail voltage, biased 400mA / channel. 2PC 500VA transformer minimum req.
It use 3 pair power mosfet like us. If I divide that bias 3X a bit over 100mA / power mosfet.
We use 55V rail voltage, around 300mA bias/ channel (each power mosfet biased to 100mA)
My question the 800VA still will be enough to power both channel??? I use only 8R speakers!
If the answer YES that would resolve a great transformer issue for me!
The rest is clear to me.
The 1R resister will give enough filtering between the HC and LC ground?
I usually use 10R to separate the signal ground from the main ground.
To power both channel front from one transformer what would be the right VA rating?
I will have to purchase something. To feed the front must be 65V or I can go up 2-3V higher.
Easier to get a transformer when we have some tolerance. Otherwise I may have to order specially manufactured= which cost $$$..
Thank you one more time!

Greetings Gabor
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Old 30th October 2012, 08:43 PM   #168
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Default Layout mode is done

Hello

Just finished the layout mod.
I have to go over to look for mistakes, but it should be OK how it is.
I did spread a bit more the power mosfets. All PC board got bigger a bit.
Here is the transformer you wrote it will do the job. That is a AA battery.
About PS capacitors I have 10PC Nippon CC 100 000uF, I don't know nothing about the quality since I never use those.
I can use 2PC Philips (those are great caps) and 2PC Nippon.
I know it will overkill but if does not degrade the sound I don't care.
I have 10PC Nippon 10 000uF 63V with solder lug type.
I will test which gave better result.
I do like large can capacitors if they are good quality, Philips, Mallory, Mepco, Cornel Dub. etc.
I did used these type successful in many Class A/B amp. 4PC set up as CRC .
Any opinion about PS caps?
Please do not forget to confirm the 800VA transformer will be good enough with 100mA bias/power device.


Greetings Gabor
Attached Images
File Type: jpg Picture 002.jpg (39.1 KB, 212 views)
File Type: jpg Picture 003.jpg (68.9 KB, 155 views)
File Type: jpg Picture 004.jpg (39.4 KB, 55 views)
File Type: bmp All fet Hitachi amplifier.bmp (90.3 KB, 30 views)
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Old 30th October 2012, 10:12 PM   #169
wahab is offline wahab  Algeria
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Join Date: Nov 2009
Location: algeria/france
[QUOTE=gaborbela;3221363]
About the transformer what is troubling me.
My

Last edited by wahab; 30th October 2012 at 10:18 PM.
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Old 31st October 2012, 01:12 AM   #170
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Hello

Here is the black layout for these amp!
I do not say final because I'll go over once again to look for any errors.
I will let you know if I'll get any error!
I just found out I have a 6PC 30 000uF 75V capacitor bank Cornell Bubblier.
That should be good for the high power PS.
I have no need for those so I can use it here.
wahab I assume you didn't forget the bias when you calculated the transformer rating, so the 800VA will be OK.
Thanks one more time to everybody for the help and a big special thanks to wahab!
The next step to purchase the transistors and resistors, each the board and test it.
Now all look promising of course after the test I will know more!
Greetings Gabor
Attached Images
File Type: bmp All fet Hitachi amplifier black.bmp (90.3 KB, 20 views)
File Type: jpg Picture 005.jpg (54.7 KB, 72 views)
File Type: jpg Picture 006.jpg (52.1 KB, 64 views)

Last edited by gaborbela; 31st October 2012 at 01:19 AM.
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