Hi,
I currently have 2 cambridge audio A5i amp that use these SAP15s, both are broken and blow fuses/melt resistors, I have tested all of the other transistors, power supply and other diodes/capacitors, so am assuming that the sankens have failed (also 2 on one particular channel give bizarre readings with my DMM).
I was just wondering if these can be replaced with the SAP16s? i was thinking perhaps a slightly improved performance or durability, or should i stick with the SAP15s as the originals?
Thanks for any help
Andy
I currently have 2 cambridge audio A5i amp that use these SAP15s, both are broken and blow fuses/melt resistors, I have tested all of the other transistors, power supply and other diodes/capacitors, so am assuming that the sankens have failed (also 2 on one particular channel give bizarre readings with my DMM).
I was just wondering if these can be replaced with the SAP16s? i was thinking perhaps a slightly improved performance or durability, or should i stick with the SAP15s as the originals?
Thanks for any help
Andy
Hi again, sorry i forgot to ask something.
If i need to replace 1 sap15, is it better to get a complete set with the same batch number? i've noticed that there is some difference between the readings between the different saps in the two different players.
I assume it will also mean i will probably have to adjust the variable resistors to get the idling current to as close to 40mA as possible.
Thanks,
Andy
If i need to replace 1 sap15, is it better to get a complete set with the same batch number? i've noticed that there is some difference between the readings between the different saps in the two different players.
I assume it will also mean i will probably have to adjust the variable resistors to get the idling current to as close to 40mA as possible.
Thanks,
Andy
Hi,
This is probably my first post in reply to an amp thread.... I don't know a huge amount about "proper" amp building yet, but I'm getting pretty good at repairing them. Please forgive my ramblings - I do tend to type a bit too much!
I saw that people were interested to hear which other amps use the Sanken transistors. Well, I just finished repairing a Denon AVR-3801 seven-channel AV amp, and it uses a pair of the SAP15 transistors per channel.
The transistor pair for the "surround back right" channel were shorted, and the resistors from the P-type emitter were open-circuit. The emitter resistors are 23.5 ohms each (well, two 0.47 ohm resistors in parallel per transistor, but you get the idea!)
The Sanken's seem to give quite a warm but powerful sound, and I've always liked that with the Denon amps. I was considering using the Denon instead of my current amp (Pioneer VSX-909), but I still think the Pioneer sounds slightly "cleaner" and controlled than the Denon (no idea which transistors the Pioneer uses).
I don't have the service manual for the Denon, so I had to adjust the idle current of the replaced trannies by checking the other channels - most of them gave a reading of around 6.1mV when the amp was warm, so I adjusted the repaired channel to be the same. One of the front channels was slightly off at around 5.2mV originally - they should really think about sticking some multi-turn pots in these things, but I know it's ALL about costs at this end of the market.
I'm not sure how the voltage relates to the current on this amp (probably just mV = mA), so I just got the repaired channel as closely matched as possible to the average current.
The Denon 1603 service manual is available online if anyone's interested in the circuit layout? (Google is your friend!) The transistor pair that the 1603 uses are the 2SB1560 and the 2SD2390, which fall between the SAP08's and the SAP10's in ratings terms. Although they are rated at 100W, the Ic current is rated at 10A? Here's a nice table of the common Sanken transistors....
http://www.sanken-ele.co.jp/en/prod/semicon/ptr/ptr_u/ptr_26e.htm
I'd be interested in suggestions for other transistor pairs for building a very simple amp. I've been meaning to build one for a while, but the parts would have to be as cheap as possible.
The Denon amps seem to be fairly highly regarded, and I was wondering what anyone else's impressions were from listening to music on some of the mainstream AV amps - can they can really compare to proper stereo amps?
I seriously don't consider myself an audiophile by any stretch, but I'm very interested in things like calibration methods and Digital Room Correction etc.
Anyway, just my two pence!
This is probably my first post in reply to an amp thread.... I don't know a huge amount about "proper" amp building yet, but I'm getting pretty good at repairing them. Please forgive my ramblings - I do tend to type a bit too much!
I saw that people were interested to hear which other amps use the Sanken transistors. Well, I just finished repairing a Denon AVR-3801 seven-channel AV amp, and it uses a pair of the SAP15 transistors per channel.
The transistor pair for the "surround back right" channel were shorted, and the resistors from the P-type emitter were open-circuit. The emitter resistors are 23.5 ohms each (well, two 0.47 ohm resistors in parallel per transistor, but you get the idea!)
The Sanken's seem to give quite a warm but powerful sound, and I've always liked that with the Denon amps. I was considering using the Denon instead of my current amp (Pioneer VSX-909), but I still think the Pioneer sounds slightly "cleaner" and controlled than the Denon (no idea which transistors the Pioneer uses).
I don't have the service manual for the Denon, so I had to adjust the idle current of the replaced trannies by checking the other channels - most of them gave a reading of around 6.1mV when the amp was warm, so I adjusted the repaired channel to be the same. One of the front channels was slightly off at around 5.2mV originally - they should really think about sticking some multi-turn pots in these things, but I know it's ALL about costs at this end of the market.
I'm not sure how the voltage relates to the current on this amp (probably just mV = mA), so I just got the repaired channel as closely matched as possible to the average current.
The Denon 1603 service manual is available online if anyone's interested in the circuit layout? (Google is your friend!) The transistor pair that the 1603 uses are the 2SB1560 and the 2SD2390, which fall between the SAP08's and the SAP10's in ratings terms. Although they are rated at 100W, the Ic current is rated at 10A? Here's a nice table of the common Sanken transistors....
http://www.sanken-ele.co.jp/en/prod/semicon/ptr/ptr_u/ptr_26e.htm
I'd be interested in suggestions for other transistor pairs for building a very simple amp. I've been meaning to build one for a while, but the parts would have to be as cheap as possible.
The Denon amps seem to be fairly highly regarded, and I was wondering what anyone else's impressions were from listening to music on some of the mainstream AV amps - can they can really compare to proper stereo amps?
I seriously don't consider myself an audiophile by any stretch, but I'm very interested in things like calibration methods and Digital Room Correction etc.
Anyway, just my two pence!
OzOnE_2k3 said:
The Sanken's have 5 pins -- you can take the emitter output from the "Source" pin and use a replacement 0.22R/5W resistor -- if indeed the emitter resistor is burned out.
I used the Sanken's with National's LM4702 "driver" chip -- could never get the distortion down below 0.01% -- take a look at National Semi application note AN-1490. The Sanken's were also used in a DIY Amplifier design from the summer 2005 issue of Elektor.
Hi,
I don't think it was the emitter resistors that were burned out. If I remember correctly, the transistors were actually shorted between the collector and emitter pins on BOTH transistors! The previous owner most probably shorted the speaker terminals while playing at high volume. One thing's for sure - he wasn't using banana plugs, 'cos those horrible plastic rivet things were still embedded in the end of the speaker terminals. (standard practice in Europe I think?)
The amp has an external 0.235 ohm resistor (sorry, NOT 23.5 ohms!) between the emitter pin and the speaker output on both transistors. This is actually made from two 0.47 ohm resistors in parallel (four total per channel).
After my post last night, I checked out many of the posts about Greg's SKA and I'm impressed by what people have said. I especially like the fact that the design has been kept fairly simple too.
So, I'll probably buy a big toroid some time and some GB150 boards. The heatsinks can be expensive though, so I'll have to break open the piggy bank when the time comes to actually build something.
One thing though - what do people think about adding protection circuitry to the GB150 (like a relay?) Does the GB150 have an anti-thump system at switch on, and does AC coupling to the speakers protect them fairly well from say - one fuse blowing?
I'd love to be able to build my own 7.1 channel system some day and add a DSP board to it that would be able to do full bass management and perhaps even DRC on all channels. I think that project may be a long way off somehow.
Ok, sorry for hijacking this thread for a while This is a great forum, I'm always reading stuff on here, so I should really think about building something soon!
OzOnE.
I don't think it was the emitter resistors that were burned out. If I remember correctly, the transistors were actually shorted between the collector and emitter pins on BOTH transistors! The previous owner most probably shorted the speaker terminals while playing at high volume. One thing's for sure - he wasn't using banana plugs, 'cos those horrible plastic rivet things were still embedded in the end of the speaker terminals. (standard practice in Europe I think?)
The amp has an external 0.235 ohm resistor (sorry, NOT 23.5 ohms!) between the emitter pin and the speaker output on both transistors. This is actually made from two 0.47 ohm resistors in parallel (four total per channel).
After my post last night, I checked out many of the posts about Greg's SKA and I'm impressed by what people have said. I especially like the fact that the design has been kept fairly simple too.
So, I'll probably buy a big toroid some time and some GB150 boards. The heatsinks can be expensive though, so I'll have to break open the piggy bank when the time comes to actually build something.
One thing though - what do people think about adding protection circuitry to the GB150 (like a relay?) Does the GB150 have an anti-thump system at switch on, and does AC coupling to the speakers protect them fairly well from say - one fuse blowing?
I'd love to be able to build my own 7.1 channel system some day and add a DSP board to it that would be able to do full bass management and perhaps even DRC on all channels. I think that project may be a long way off somehow.
Ok, sorry for hijacking this thread for a while
This is a great forum, I'm always reading stuff on here, so I should really think about building something soon!OzOnE.
Hi,
gb150 does not need an anti-thump at switch on. It is completely silent!
The fuses are located such that a blown output device cannot cause output offset. No DC protection required.
The breaking of a fuse due to speaker lead shorting does not result in output offset.
Input muting would be nice though, it suffers from high current pulses when removing or plugging in the input RCAs live (I know one shouldn't, but I did, with the speakers disconnected immediately after switching off).
There is maximum current protection already fitted and this should prevent output stage failure until the fuses have time to break.
gb150 does not need an anti-thump at switch on. It is completely silent!
The fuses are located such that a blown output device cannot cause output offset. No DC protection required.
The breaking of a fuse due to speaker lead shorting does not result in output offset.
Input muting would be nice though, it suffers from high current pulses when removing or plugging in the input RCAs live (I know one shouldn't, but I did, with the speakers disconnected immediately after switching off).
There is maximum current protection already fitted and this should prevent output stage failure until the fuses have time to break.
Greg's amps sound like great designs if they don't have the thump at switch on!
What would be a good way to implemented the input mute? What causes the current peaks? - is it the fact that when an RCA plug is removed, the ground connection gets disconnected first for a split second? Would AC coupling of the inputs help with this?
I wouldn't say that my speakers are expensive, but if I ever get round to building an amp, it would be nice to have piece of mind from proper protection circuits. I'm only using M&K LCR-55's at the moment, but I may buy some better (and bigger) speakers soon.
Any opinions on the M&K stuff btw?
What would be a good way to implemented the input mute? What causes the current peaks? - is it the fact that when an RCA plug is removed, the ground connection gets disconnected first for a split second? Would AC coupling of the inputs help with this?
I wouldn't say that my speakers are expensive, but if I ever get round to building an amp, it would be nice to have piece of mind from proper protection circuits. I'm only using M&K LCR-55's at the moment, but I may buy some better (and bigger) speakers soon.
Any opinions on the M&K stuff btw?
Hi,
I have AC coupling and it happens. The omission of the input DC blocking cap (an option) causes output offset problems for all partially DC coupled amplifiers, so I avoid it and always use DC blocking at the input and at the NFB loop.
I have another set of amps that blows a fuse if the RCA is momentarily disturbed and that causes 70V DC offset (never blown a speaker yet!).
I have AC coupling and it happens. The omission of the input DC blocking cap (an option) causes output offset problems for all partially DC coupled amplifiers, so I avoid it and always use DC blocking at the input and at the NFB loop.
I have another set of amps that blows a fuse if the RCA is momentarily disturbed and that causes 70V DC offset (never blown a speaker yet!).
The guy who said he didn't like darlingtons should have explained why...
Most poweramps work in class AB which means :
- if Vout > x, upper transistor is linear and lower transistor is blocked
- if Vout < -x, upper transistor is blocked and lower transistor is linear
- if -x < Vout < x, both transistore are linear
x being normally much lower than a volt.
so, the transistors must switch very quickly from linear mode to blocked mode.
If clipping is to be clean, they also should switch quickly from saturated (clipped) to linear mode (unclipped), else you get "clipping hangover".
In order to do this quickly, you must pump out the stored charges in the base pretty quickly. This is done by the driver stage (if designed properly) which pulls out a negative current from the base. However, this is not possible in a darlington, because if you try to pull current from the base, the first transistor will block, and the second one will only have the embedded resistor to work with.
This is why darlingtons give worse crossover distortion and much worse clipping behaviour (see Douglas Self's book).
Most poweramps work in class AB which means :
- if Vout > x, upper transistor is linear and lower transistor is blocked
- if Vout < -x, upper transistor is blocked and lower transistor is linear
- if -x < Vout < x, both transistore are linear
x being normally much lower than a volt.
so, the transistors must switch very quickly from linear mode to blocked mode.
If clipping is to be clean, they also should switch quickly from saturated (clipped) to linear mode (unclipped), else you get "clipping hangover".
In order to do this quickly, you must pump out the stored charges in the base pretty quickly. This is done by the driver stage (if designed properly) which pulls out a negative current from the base. However, this is not possible in a darlington, because if you try to pull current from the base, the first transistor will block, and the second one will only have the embedded resistor to work with.
This is why darlingtons give worse crossover distortion and much worse clipping behaviour (see Douglas Self's book).
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