Luke said:
I'm glad you like it
. My JLH still isn't finished . All circuits are soldered, but I need to make a case and the person I need to help me with this is on vacation...Oh, and the images in that url don't work anymore. These do however: http://members.lycos.nl/anthonyvh/index.php?page=jlh
transformer usage.
Hello.
What shall I do?
I have been bitten by the Hood 10 W Class A bug....
I have two identical transformer 24 volt 5 amperes.
And some thoughts.
1. Build two monoblocks with single supply voltage.
2. Build a two channel amp with the two transformers secondarys in parallel giving a single supply voltage of 24 V 10 A.
3. Build a two channel amp with the two secondarys in series to give a dual polarity supply.
For the moment I would like to run the amps with unregulated power suppplies, how much capacitor capacity is then needed to get a proper result ?
And then i will add regulated power at a later moment.
The reason for this is that money is short and that I have the parts to build the amplifier.
Tuben
Hello.
What shall I do?
I have been bitten by the Hood 10 W Class A bug....
I have two identical transformer 24 volt 5 amperes.
And some thoughts.
1. Build two monoblocks with single supply voltage.
2. Build a two channel amp with the two transformers secondarys in parallel giving a single supply voltage of 24 V 10 A.
3. Build a two channel amp with the two secondarys in series to give a dual polarity supply.
For the moment I would like to run the amps with unregulated power suppplies, how much capacitor capacity is then needed to get a proper result ?
And then i will add regulated power at a later moment.
The reason for this is that money is short and that I have the parts to build the amplifier.
Tuben
in series
Tuben,
the most logical thing to do seems using the 2 transformers in series in order to get a symmetrical power supply giving you around plus and minus 30 Volts DC. Using a passive power supply with 4 capacitors of around 10.000 mF/40V (per rail in between them a power resistor of .47 Ohm/25Watts) will do. Of course you will use the latest version of the circuit as described on the site of Geoff Moss (version 2003). Available power will be around 30-40 Watt RMS stereo depending on the amount of idle current. You have to take care of enough cooling however.
Rudy
Tuben,
the most logical thing to do seems using the 2 transformers in series in order to get a symmetrical power supply giving you around plus and minus 30 Volts DC. Using a passive power supply with 4 capacitors of around 10.000 mF/40V (per rail in between them a power resistor of .47 Ohm/25Watts) will do. Of course you will use the latest version of the circuit as described on the site of Geoff Moss (version 2003). Available power will be around 30-40 Watt RMS stereo depending on the amount of idle current. You have to take care of enough cooling however.
Rudy
3906
Tuben is back
I decided to check the hfe of the transistors that is possible to use in Hood's Class A amp.
And the two 2N3906 I have measured out to have an hfe of 5 and 6!
All the other types I checked were ok; 2n3055, BC212, 2N1711 ao.
Are a hfe of 5 and 6 typical for 2N3906? I was waiting for something between 100-300.
Tuben
Tuben is back
I decided to check the hfe of the transistors that is possible to use in Hood's Class A amp.
And the two 2N3906 I have measured out to have an hfe of 5 and 6!
All the other types I checked were ok; 2n3055, BC212, 2N1711 ao.
Are a hfe of 5 and 6 typical for 2N3906? I was waiting for something between 100-300.
Tuben
I stand corrected
Tuben again.
I decided to test the 3906's one more time. This time with my glasses on.
And this time they measured 188 and 199.
So it was either the swedish trolls that affected my test and if they are innocent, I perhaps need to wear my glasses all the time.
By the way I have decided to build two monoblocks in one case.
So it will be single polarity capacitor multiplier psu's and output caps.
Tuben
Tuben again.
I decided to test the 3906's one more time. This time with my glasses on.
And this time they measured 188 and 199.
So it was either the swedish trolls that affected my test and if they are innocent, I perhaps need to wear my glasses all the time.
By the way I have decided to build two monoblocks in one case.
So it will be single polarity capacitor multiplier psu's and output caps.
Tuben
Any japanese site deals with oversea customers ??
I am looking for the Toshiba transistors 2SC3421, 2SA1358
2SA 1302, 2SC3281, 2sc5200, 2SA1943 etc
There are a lot of fake transistor out there in the market.
I want to buy genuine transistor from Japan, but most of the
japanese suppliers on the internet are in Japanese.
Anyone know a japanese website in English and willing to
deal with oversea customers/mail order ??
I am looking for the Toshiba transistors 2SC3421, 2SA1358
2SA 1302, 2SC3281, 2sc5200, 2SA1943 etc
There are a lot of fake transistor out there in the market.
I want to buy genuine transistor from Japan, but most of the
japanese suppliers on the internet are in Japanese.
Anyone know a japanese website in English and willing to
deal with oversea customers/mail order ??
Hi kambule
www.cricklewoodelectronics.com
these people are very easy to deal with.
genuine toshiba parts.
small orders not a problem.
excellent on line catalogue.
current 2SC3421 in stock are all hfe=160 gain range but only 6mm lead length.
good luck ....... Graham.
www.cricklewoodelectronics.com
these people are very easy to deal with.
genuine toshiba parts.
small orders not a problem.
excellent on line catalogue.
current 2SC3421 in stock are all hfe=160 gain range but only 6mm lead length.
good luck ....... Graham.
Toshiba transistors
Graham, Many thanks.
Wonder how you know the transistor hfe are 160. I can't find
this info on the webpage and it doesnt say it is made by Toshiba.
May be the info are on the download cataloge but I cant download it. May be it was a temporary server problem. I shall try later.
kb
Graham, Many thanks.
Wonder how you know the transistor hfe are 160. I can't find
this info on the webpage and it doesnt say it is made by Toshiba.
May be the info are on the download cataloge but I cant download it. May be it was a temporary server problem. I shall try later.
kb
I can report success with Sanken 2sc1577 as output trannies in the JLH for quad amp circuit as per Geoff's Class A website and with a couple of minor mods. Each channel has 4 x 2sc1577 running at about 1.4 amps Iq. Part selection (ie the 2sc1577) was deterimned by what was on special at my favourite parts outlet!! Stability doesn't seem to be an issue and they sound every bit as good as all the reports for other types on this thread. Have purchased mj15003s to try later in the year. Layout follows Argo's (post 187 on this thread). Power supply is 45000 uf (3 x 15000) per side followed by a capacitor multiplier a la Rod Elliot and housed remote from the amp.
Ric
Ric
Re: Any news with JLH update?
Hi Ralf
IMO, the MJ21194 is not the best option, but by all means try it and report back.
The datasheet for the MJ21194 quotes a gain of 25-75 at 8A and shows a typical dc current gain of just over 100 at 2A and a Tj of 100°C. I have measured a dozen or so 21194s (in MJL package) and the gain varied between 60 and 90 at 2A (albeit at probably a slightly lower Tj).
The datasheet for the MJ15003 quotes a gain of 25-150 at 5A. Unfortunately there is no graph for a typical device but I would expect the gain at 2A to be higher than that for the MJ21194. I have yet to measure any samples of this device but will do so now that I have sorted out a new tester (see Project 106 at Rod Elliott's pages).
Ideally, for the JLH I think that we should be looking for output transistors with a gain of 120-150 at 2A (the higher the better) and an ft of around 4mHz. Also, the devices should be gain-linear from an Ic of 100mA (or less) to 3A.
Geoff
ralf said:
Hi Ralf
IMO, the MJ21194 is not the best option, but by all means try it and report back.
The datasheet for the MJ21194 quotes a gain of 25-75 at 8A and shows a typical dc current gain of just over 100 at 2A and a Tj of 100°C. I have measured a dozen or so 21194s (in MJL package) and the gain varied between 60 and 90 at 2A (albeit at probably a slightly lower Tj).
The datasheet for the MJ15003 quotes a gain of 25-150 at 5A. Unfortunately there is no graph for a typical device but I would expect the gain at 2A to be higher than that for the MJ21194. I have yet to measure any samples of this device but will do so now that I have sorted out a new tester (see Project 106 at Rod Elliott's pages).
Ideally, for the JLH I think that we should be looking for output transistors with a gain of 120-150 at 2A (the higher the better) and an ft of around 4mHz. Also, the devices should be gain-linear from an Ic of 100mA (or less) to 3A.
Geoff
I have made a JLH'96 amp with Sanken 2SC2837
http://www.ampslab.com/PDF/2sc2837.pdf
To make it stable additional capacitor is needed from VA transistor collector to feedback point. After that I never had problems with stability.
If you are interested I have to check the value of the cap at home and report back.
**
Actually my JLH'96 modules are sitting on shelf and are up to grabs if anyone is interested. I moved and got married so no longer had the space for monstrous class A monoblocks.
Ergo
http://www.ampslab.com/PDF/2sc2837.pdf
To make it stable additional capacitor is needed from VA transistor collector to feedback point. After that I never had problems with stability.
If you are interested I have to check the value of the cap at home and report back.
**
Actually my JLH'96 modules are sitting on shelf and are up to grabs if anyone is interested. I moved and got married
so no longer had the space for monstrous class A monoblocks.Ergo
