Why don't you have a look at the amp in question.
https://audio-database.com/ONKYO/amp/integram-505-e.html
It's quite prominent as if it was tuned to sound that way. It sold with a special preamp that doesn't match other amps very well.
Hi Chris,
TheSoundMann should know now you are an opinionated fellow. Not everyone agrees. I will agree with you that people do tend to get used to a sound, but don't agree that's always the only effect.
I am familiar with them.
That is one service I perform, but I have to work with the equipment on my bench. As far as board layout is concerned, much easier to look and see in person, you can miss so much in pictures. Even materials can matter sometimes.
It was not tuned to sound that way. Back then you had to measure and listen carefully. You should still do that today, but generally at the levels we see now, if it measures well it in fact does sound good. I would never not listen to something though.
That is one service I perform, but I have to work with the equipment on my bench. As far as board layout is concerned, much easier to look and see in person, you can miss so much in pictures. Even materials can matter sometimes.
It was not tuned to sound that way. Back then you had to measure and listen carefully. You should still do that today, but generally at the levels we see now, if it measures well it in fact does sound good. I would never not listen to something though.
Well, experienced.
Often we don't agree simply because you don't have access to the experience and equipment I do (and many others). My bet is that we would be in perfect agreement given the same experiences. I have a stupid amount of money invested in test equipment.
Don't forget, I get paid to optimize existing designs and equipment. This is one of my jobs.
Often we don't agree simply because you don't have access to the experience and equipment I do (and many others). My bet is that we would be in perfect agreement given the same experiences. I have a stupid amount of money invested in test equipment.
Don't forget, I get paid to optimize existing designs and equipment. This is one of my jobs.
Depends on what film cap type and where in the circuit it goes. Matching the input transistors (voltage amp) also helps a great deal. If they are matched already, great.
Just look at the schematic. It has two gain stages + an intermediate emitter follower pair which equals massive open loop gain. The amplifier has a closed loop gain of 19x (25.5dB).
None of the diff amps has any degeneration and I can only guess that the open loop gain is over 100dB. That means that there is a lot of negative feedback and typically those kinds of numbers lead to the type of sound you hear, strident and clinical with no warmth. Crown DC300 original version and pretty much all amps form the 1970's sounded like this.
Yes you can replace all the caps you want but you cannot change the design except to add emitter degeneration to the diff amp stages to lower the open loop gain, thus reducing the amount of feedback.
I always place base stoppers into emitter followers and these should be added to Q205/Q206 (220-470 ohms), Q211/Q212 (220 ohm) and Q213/Q214 about 10-15 ohm.
The bias spreader cannot compensate for a 6 x Vbe output stage and so you are not able to set the idle current to a reasonable value as thermal runaway is a possibility.
Lastly I would configure the level controls into a shunt format where the signal only passes through two metal film resistors and not the pot.
None of the diff amps has any degeneration and I can only guess that the open loop gain is over 100dB. That means that there is a lot of negative feedback and typically those kinds of numbers lead to the type of sound you hear, strident and clinical with no warmth. Crown DC300 original version and pretty much all amps form the 1970's sounded like this.
Yes you can replace all the caps you want but you cannot change the design except to add emitter degeneration to the diff amp stages to lower the open loop gain, thus reducing the amount of feedback.
I always place base stoppers into emitter followers and these should be added to Q205/Q206 (220-470 ohms), Q211/Q212 (220 ohm) and Q213/Q214 about 10-15 ohm.
The bias spreader cannot compensate for a 6 x Vbe output stage and so you are not able to set the idle current to a reasonable value as thermal runaway is a possibility.
Lastly I would configure the level controls into a shunt format where the signal only passes through two metal film resistors and not the pot.
Which means something.
As in: "cap brand or price does not affect sound"
We can definitely measure way better than in the 80's
But can we hear better?
Much doubt so.
Meaning: measuring -100 or -120dB is better than "only" -80dB
Can we hear 20-30-40 dB better? 🤔
Resistors from emitter to ground?
This amp never seems to get warm, even when driven hard.
How will this improve the amps performance?
Look up the Onkyo P-303. It is a totally pure and discreet dual mono preamp (600 Ohms).
https://audio-database.com/ONKYO/amp/integrap-303-e.html
I listened to the amp again, this time without the chinese made connectors on my speaker wires.
It sounded much better and easier to listen too.
I was using my Sony ES receiver as a preamp. The amp sounds best with a warm smooth model like my Sony.
https://audio-database.com/ONKYO/amp/integrap-303-e.html
I listened to the amp again, this time without the chinese made connectors on my speaker wires.
It sounded much better and easier to listen too.
I was using my Sony ES receiver as a preamp. The amp sounds best with a warm smooth model like my Sony.
What makes you think stuff like this can be fixed merely by cap swap?
The circuit is clearly based on Otala's amp, like the early Electrocompaniet's amps, but there are notable differences too. Series vs shunt feedback, different compensation, much cooler biasing in your amp. With some knowledge and a lot of patience it might be possible to make the circuit behave more like an EC amp. Maybe.
Then, there are all the other unknowns that make an amp. Ime everything contributes to the sound: power transformer, main power caps, rectification, transistor types, chassis material, relays, especially old and corroded.
Dull Russian caps will probably turn the sound dull, but will it be an improvement?
Negative feedback, properly implemented in a good circuit is a very good thing. The more, the better. You do want more linear operation in the input stages (everywhere really - within reason). The emitter degeneration reduces the effect of mismatched transistors in a pair as well as making them more linear at the expense of transconductance. It is a careful balance, a trade-off. Match the transistors, but you don't have that ability.
The basic circuit and layout on the board are things you cannot change. If there is a problem there, you cannot improve the sound quality past a certain point. A great example of this was the SymAsym, same circuit, but a board layout change really improved it.
The basic circuit and layout on the board are things you cannot change. If there is a problem there, you cannot improve the sound quality past a certain point. A great example of this was the SymAsym, same circuit, but a board layout change really improved it.