The gain of the 2sc2240 is not causing the problem you are experiencing.
More ideas;
Try checking the resistor values in the input stage (measure them). Also measure the values in the feedback loop (red, brown & orange can often be mistaken or poorly printed)
Check / replace the feedback capacitors (100uF).
Use the schematic that shows the current flows for each stage and verify (by measuring voltages) that you have these.
You can increase the gain of the amp using a 47k resistor.
Good luck
More ideas;
Try checking the resistor values in the input stage (measure them). Also measure the values in the feedback loop (red, brown & orange can often be mistaken or poorly printed)
Check / replace the feedback capacitors (100uF).
Use the schematic that shows the current flows for each stage and verify (by measuring voltages) that you have these.
You can increase the gain of the amp using a 47k resistor.
Good luck
AndrewT said:
Hi Andrew,
The grades I purchased were the 2SC2240BL and 2SC1845F. Those were the only grades they carried, so those were all I could purchase.
Both measured hFE in their respective ranges as I recall. If you need me to take some out and measure their hFE let me know.Based on quasi's last message maybe the hFE DC gain is not really the cause of problem Miodrag is experiencing. I certainly do not have the knowledge to know if hFE is or is not the issue affecting both of Miodrag's modules.
Regards,
John L. Males
Willowdale, Ontario
Canada
15 May 2006 13:39
15 May 2006 13:44 Opps bad typo corrected
Hi guys,
Problem solved!
The store where I purchase my electronic parts gave me wrong resistor value(33k=3k3). I realy don't know how I did not notice this before.
Anyway now I'm really satisfied with the power of modules.
Thanks for help!!!
Soon I will post pictures of amp in the case...
Regards,
Miodrag Pejin
Problem solved!
The store where I purchase my electronic parts gave me wrong resistor value(33k=3k3). I realy don't know how I did not notice this before.
Anyway now I'm really satisfied with the power of modules.
Thanks for help!!!
Soon I will post pictures of amp in the case...
Regards,
Miodrag Pejin
Miodrag,
Very happy you found the source of problem with quasi's help and are now a very happy audio person with the completed modules.
I was tempted to suggest check the resistors and capacitors. I just assumed not a likely case. You are very careful and thoughtful in what you do and why. Oh well we all slip up at times. I know from the places I buy parts the part in box is too often not what box is labled as. Sadly this almost certainly caused by the curtomers taking something out and forgetting where took from and just drop in what is most convient for them. I take meters for resistors and capacitors with me to be certain what I think I am buying for a value is the value I wanted.
I been burned by this misplaced parts problem a few too many times from places other than say an ElectroSonic we have locally here. ElectroSonic on their own initiative places transistors, bridges, diodes and ICs in antistatic bags on a part number by part number basis. The places I source from usually, as ElectronSonic does not have many parts/quanities allowed I need, are surplus places. Therefore the reason for caution using meters.
At least this resistor mix up did not cause a module to blow up for you due to store mix up. Which resistor was it that was wrong, R3 or R17 or both?
Regards,
John L. Males
Willowdale, Ontario
Canada
15 May 2006 18:53
Very happy you found the source of problem with quasi's help and are now a very happy audio person with the completed modules.
I was tempted to suggest check the resistors and capacitors. I just assumed not a likely case. You are very careful and thoughtful in what you do and why. Oh well we all slip up at times. I know from the places I buy parts the part in box is too often not what box is labled as. Sadly this almost certainly caused by the curtomers taking something out and forgetting where took from and just drop in what is most convient for them. I take meters for resistors and capacitors with me to be certain what I think I am buying for a value is the value I wanted.
I been burned by this misplaced parts problem a few too many times from places other than say an ElectroSonic we have locally here. ElectroSonic on their own initiative places transistors, bridges, diodes and ICs in antistatic bags on a part number by part number basis. The places I source from usually, as ElectronSonic does not have many parts/quanities allowed I need, are surplus places. Therefore the reason for caution using meters.
At least this resistor mix up did not cause a module to blow up for you due to store mix up. Which resistor was it that was wrong, R3 or R17 or both?
Regards,
John L. Males
Willowdale, Ontario
Canada
15 May 2006 18:53
Hey good looking
What happens when the output of this amp is shorted?
I think I read the entire thread and I'm suprised more people are not trying this design and posting pics and feedback? I saw a +/-supply voltage versus number of output devices used table. I can't see it any more, repost?
Has anyone built this with a different PCB lauout?
I like it, it's on my list and I just ordered 20 IRFP's. If I get it up and running I'll have 3 power amps without cases
but I'm working on it.
Shawn.
What happens when the output of this amp is shorted?
I think I read the entire thread and I'm suprised more people are not trying this design and posting pics and feedback? I saw a +/-supply voltage versus number of output devices used table. I can't see it any more, repost?
Has anyone built this with a different PCB lauout?
I like it, it's on my list and I just ordered 20 IRFP's. If I get it up and running I'll have 3 power amps without cases
but I'm working on it.Shawn.
keypunch said:
Like my ting says, I'm downtown TO and I like to buy local when ever I can. Local means visiting Active Surplus on Queen Street. Supremetronic on College Street now called Honson. Sayal Electronics in Scarborough and in Mississauga. More surplus at A1 Electronics. Still, you can drive to Hamilton for tube stuff from TheTubeStore.com (phone in orders in advance) I order direct from Hammond and Plitron and pick up my orders myself. Hammond has a museum to visit and they always give me a Tim Hortons coffee coupon
NOS tubes from an old TV repair guy in his 80's downtown and on the verge of selling his biz, basement used to be full of valves as the old fart loved them and couldn't part by tossing them in the garbage, the nineties hit and he's made a small fortune. Supply is running thin now and I'm certain he'll sell the building and collect his realestate millions. I went to one tube swap but it was all RF radio dudes and there was almost nothing going on regarding audio.
And of course mail order from everywhere. Duty is included when you buy from a stocking Canadian company like Solen in Quebec vs. Madisound in the U.S. The only thing I ever purchased from eBay was a laptop battery for IBM380Z and the supplier turned out to be in Ontario! Go figure?
And finally my own stash which I've been working on since I was a kid in the seventies
Happy hunting,
Shawn.
Re: Hey good looking
You're obviously referring to the Cat.
If you short this amp practically nothing happens (anymore that is). The amp does not have short cct protection apart from the fuses and it is likely that a short cct will destroy the output FETs. It would be quite easy to add protection....on a new thread perhaps.
The table can be found here http://www.diyaudio.com/forums/showthread.php?postid=794932#post794932
I too would like to see variations of constructions posted here.
I estimate about 20+ amps have been built so far, most constructors though seem to prefer anonymity and have communicated with me via email. That's cool too.
My workbench is currently hosting a father & son team who are building a stereo setup each. They ordered $400 AUS of transformers and capacitors today (so commitment has been demonstrated). I'll post piccies of their efforts shortly.
Good luck with your construction.
Cheers
Quasi
TomWaits said:What happens when the output of this amp is shorted?
I think I read the entire thread and I'm suprised more people are not trying this design and posting pics and feedback? I saw a +/-supply voltage versus number of output devices used table. I can't see it any more, repost?
Has anyone built this with a different PCB lauout?
I like it, it's on my list and I just ordered 20 IRFP's. If I get it up and running I'll have 3 power amps without cases
Shawn.
You're obviously referring to the Cat.
If you short this amp practically nothing happens (anymore that is). The amp does not have short cct protection apart from the fuses and it is likely that a short cct will destroy the output FETs. It would be quite easy to add protection....on a new thread perhaps.
The table can be found here http://www.diyaudio.com/forums/showthread.php?postid=794932#post794932
I too would like to see variations of constructions posted here.
I estimate about 20+ amps have been built so far, most constructors though seem to prefer anonymity and have communicated with me via email. That's cool too.
My workbench is currently hosting a father & son team who are building a stereo setup each. They ordered $400 AUS of transformers and capacitors today (so commitment has been demonstrated). I'll post piccies of their efforts shortly.
Good luck with your construction.
Cheers
Quasi
Goodies
I recieved a rail of IRFP450's as samples today Then I picked up $40 of caps and new drill bits for the press. Also got some more PCB etching gear. THEN I picked up some FAMILY at the airport, so that shuts me down for a little while. I should have some progress in a week or so. Shawn.
I recieved a rail of IRFP450's as samples today
Then I picked up $40 of caps and new drill bits for the press. Also got some more PCB etching gear. THEN I picked up some FAMILY at the airport, so that shuts me down for a little while. I should have some progress in a week or so. Shawn.
TomWaits said:
Like my ting says, I'm downtown TO and I like to buy local when ever I can. Local means visiting Active Surplus on Queen Street. Supremetronic on College Street now called Honson. Sayal Electronics in Scarborough and in Mississauga. More surplus at A1 Electronics. Still, you can drive to Hamilton for tube stuff from TheTubeStore.com (phone in orders in advance) I order direct from Hammond and Plitron and pick up my orders myself. Hammond has a museum to visit and they always give me a Tim Hortons coffee coupon
NOS tubes from an old TV repair guy in his 80's downtown and on the verge of selling his biz, basement used to be full of valves as the old fart loved them and couldn't part by tossing them in the garbage, the nineties hit and he's made a small fortune. Supply is running thin now and I'm certain he'll sell the building and collect his realestate millions. I went to one tube swap but it was all RF radio dudes and there was almost nothing going on regarding audio.
And of course mail order from everywhere. Duty is included when you buy from a stocking Canadian company like Solen in Quebec vs. Madisound in the U.S. The only thing I ever purchased from eBay was a laptop battery for IBM380Z and the supplier turned out to be in Ontario! Go figure?
And finally my own stash which I've been working on since I was a kid in the seventies
Happy hunting,
Shawn.
Hi Shawn,
Sorry I have been busy and for some reason the forum has not eMailed me since my last posting to this thread. I have eMail from other threads.
Thanks for the answer. I was aware from your profile at side of the postings you were downtown. Exactly why I asked. I was curious if there were some other sources that could be useful for me.
I been to A1 Electronics and really have not seen much for amp building parts use. I have been to Active for years. I sometimes find their prices much higher than "Supremetronic on College Street now called Honson" or ElectroSonic. I have made a few inquiries to Sayal Electronics, but I find they are difficult to get pricing on, and found many of their parts to be much more expensive than most other sources, even with last years exchance tates, S/H. I generally find no duty is assessed, just the usual PST/GST. I have called Plitron a couple times for quick question anout Toroids, and they have always been clear and accurate. Sadly I cannot afford buying from Plitron. Plitron is just bit out of my limited budget. Certainly Plitron has excellent product and quality.
I never knew about TubeStore.com. Next time I am in Hamilton I will check them out. I have a DL-34 and couple Dynco 70's that would be worth stocking up on some spare tubes.
Thanks again for your reply Shawn.
Regards,
John L. Males
Willowdale, Ontario
Canada
21 May 2006 03:26
Short cct detector;
This is the idea I had for a simple short cct detector. Abnormally high currents will briefly turn on the optocoupler transistor providing a logic "low" on its collector.
This can be used to trigger other circuits, i.e. power supply disconnect, FET gate shunt, speaker disconnect etc.
My preference would be for the "low" logic pulse to apply a permanent condition forcing the amp user to power down in order to reset the system.
I decided on an optocoupler so that protection circuitry would be physically seperate from the amp. This removes the possibilty of some weird condition preventing effective operation.
Theoretical only at this stage. Any thoughts?
Cheers
This is the idea I had for a simple short cct detector. Abnormally high currents will briefly turn on the optocoupler transistor providing a logic "low" on its collector.
This can be used to trigger other circuits, i.e. power supply disconnect, FET gate shunt, speaker disconnect etc.
My preference would be for the "low" logic pulse to apply a permanent condition forcing the amp user to power down in order to reset the system.
I decided on an optocoupler so that protection circuitry would be physically seperate from the amp. This removes the possibilty of some weird condition preventing effective operation.
Theoretical only at this stage. Any thoughts?
Cheers