Hi, I recently purchase a Philips BC337-40 & Philips BC327-25 for the X10D tube buffer project.
My questions is will the different DC current gain on transistor affect sound imbalance or any bad effect on the circuit?
How about different manufacturers, Philips BC337/40 & Fairchild BC327/40, will this cause sound imbalance?
My questions is will the different DC current gain on transistor affect sound imbalance or any bad effect on the circuit?
How about different manufacturers, Philips BC337/40 & Fairchild BC327/40, will this cause sound imbalance?
If you are in Europe I can send you both of the same brand. Your fear for sound imbalance is justified but it won't be caused by the transistors: X10D is a totally superfluous device only introducing distortion and worse drive capability. I used to service these and was already then surprised that it became so popular. Voltages are quite low too. This device is a confirmation to techs that consumers usually prefer the worst of devices.
It was meant to "enhance" the non perfect sound quality of CD players of that time. DAC technology has improved, opamps have improved, circuits have improved. This causes X10D to be an effect generator of sorts in this day and age. If it should "enhance" or add "tube magic" then please consider the fact that the output stage of the source still has opamps in it. In other words: improving output stages is a way better solution than adding another circuit as a chain is as strong as its weakest link.
Exxagerated examples:
1. a bad sounding DAC with ua741 output stage coupled to an X10D will still have ua741 as IV stage......
2. a CD player with OPA1656 (excellent!) output stage will still be excellent and nothing will improve by adding X10D. Probably the contrary....
It is like adding sugar to sour beer. The sugar won't hide the fact that the beer is bad. Sugar will destroy your teeth so don't add sugar, just buy better beer.
It was meant to "enhance" the non perfect sound quality of CD players of that time. DAC technology has improved, opamps have improved, circuits have improved. This causes X10D to be an effect generator of sorts in this day and age. If it should "enhance" or add "tube magic" then please consider the fact that the output stage of the source still has opamps in it. In other words: improving output stages is a way better solution than adding another circuit as a chain is as strong as its weakest link.
Exxagerated examples:
1. a bad sounding DAC with ua741 output stage coupled to an X10D will still have ua741 as IV stage......
2. a CD player with OPA1656 (excellent!) output stage will still be excellent and nothing will improve by adding X10D. Probably the contrary....
It is like adding sugar to sour beer. The sugar won't hide the fact that the beer is bad. Sugar will destroy your teeth so don't add sugar, just buy better beer.
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It is capacitance multiplier with current limiter. Higher hFE is higher PSSR (Power Supply Rejection Ratio).
Even better is to up the voltages and regulate after capacitance multipliers. Still it is polishing a turd.
I bought a Chinese version a few years ago.
I did some measurements and found the distortion increased rapidly when the output exceeded only 200mv RMS so I agree with Jean-Paul, best avoided.
I tried different tubes to no avail.
I did some measurements and found the distortion increased rapidly when the output exceeded only 200mv RMS so I agree with Jean-Paul, best avoided.
I tried different tubes to no avail.
You don't need regulation with tubes, but you clearly need low noise with starved anodes.
You don't need regulated voltage, you don't need to build tidy, you don't need audio at all. I can come up with a lot of self defined truths 🙂
It is a device liked by people with AMM only judgement (Analog Multi Meters also known as ears). The AMM's can easily be fooled certainly when the crowd tells the device is good and when the device glows. This is believed since 1996! The X-Pre is similar, plain bad quality both with longevity (always kaputt) and soundwise. The DACs (I owned them) are also only good for recycling.
It probably is a good idea to predefine what is needed in a chain and to be aware that gear needs to have a function. Unneeded functions/features or even superfluous devices generally don't make matters better. One can demonstrate this easily with a minimal but standardized chain. The impression is that insertion of superfluous devices (preferably with equally superfluous GAIN) is an untreated and therefor incurable virus in tube audio while standardization is treated with heavy medication.
It is a device liked by people with AMM only judgement (Analog Multi Meters also known as ears). The AMM's can easily be fooled certainly when the crowd tells the device is good and when the device glows. This is believed since 1996! The X-Pre is similar, plain bad quality both with longevity (always kaputt) and soundwise. The DACs (I owned them) are also only good for recycling.
It probably is a good idea to predefine what is needed in a chain and to be aware that gear needs to have a function. Unneeded functions/features or even superfluous devices generally don't make matters better. One can demonstrate this easily with a minimal but standardized chain. The impression is that insertion of superfluous devices (preferably with equally superfluous GAIN) is an untreated and therefor incurable virus in tube audio while standardization is treated with heavy medication.
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I made a starved anode circuit back in 2004 for a friend who's a guitar player, based on a circuit from " la paya" series of starved anode circuits...I kinda know what starved anode circuits do. Ended up with cloning Carvin, Mesa dual rectifier and other devices to do a proper distortion effect.
It deffinitely doesn't help at anything having true regulators with such circuits.
It deffinitely doesn't help at anything having true regulators with such circuits.
That's true...it would be a very bad use for 2 x ecc88 tubes but being easy to make and quite safe it ads to the experience..Behringer used 6n1p for that role to get cheaper, but I had to try 3...4 of them in a behringer to find one with less noise...The whole concept is indeed flawed cause ecc8 are very good tubes in classic circuits.
I just expressed my opinions about the regulator part...
I just expressed my opinions about the regulator part...
For a change we'll be back on topic.
1. Not likely but I understand the insecurity.
2. Generally audio people want same brand and series. This feels better but technically it is debatable.
So it is emotions. We are all somewhat/sometimes sensitive to ridiculous details so I would use BC327/25 and BC337/25 by the same brand and go on. I do the same with 78xx/79xx and such. Why not? There is no law that forbids stuff to look esthetically pleasing AFAIK and things won't get worse or something like that.
Looks like an effects box to me; supply voltage is ludicrously low for any serious amplification job.
That said, those transistors will work fine.
In any case, original MPSA42/92 transistors are very poor performers anyway, where designers sacrificed everything for high voltage (think 200-300V) operation, wasted here on plain vanilla +/-32V.
Even the worst BC327/337 pair will work better than the original ones, go figure.
As a side note, p1ss poor power supply uses a voltage doubler starting with 12VAC to barely achieve +/-30V rails.
That´s why they use capacitance multipliers: they don´t have enough voltage available for proper regulation.
Bonus points for the half wave rectified filament supply 😱
EDIT:
Which grossly increases distortion, makes it easier for GK diode to clip, etc. , but who´s counting?
"Fine" 🙄 for an effects box.
That said, those transistors will work fine.
In any case, original MPSA42/92 transistors are very poor performers anyway, where designers sacrificed everything for high voltage (think 200-300V) operation, wasted here on plain vanilla +/-32V.
Even the worst BC327/337 pair will work better than the original ones, go figure.
As a side note, p1ss poor power supply uses a voltage doubler starting with 12VAC to barely achieve +/-30V rails.
That´s why they use capacitance multipliers: they don´t have enough voltage available for proper regulation.
Bonus points for the half wave rectified filament supply 😱
EDIT:
WAY too low supply voltage to begin with, plus high current needed to drive that low (for an ECC88) 10k plate load, so they probably NEEDED 0V bias to pass enough current.
Which grossly increases distortion, makes it easier for GK diode to clip, etc. , but who´s counting?
"Fine" 🙄 for an effects box.
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Bravo JMFahey, I couldn't have put it any better.
Off topic alarm!!!!!! BC327 and BC337 are lower noise than the BC550, BC560 etc but still the latter are very often chosen in low noise designs. Go figure. I suspect if we start debating that painting your hair pink will give a better sound experience and we persevere in spreading the truth we'll see pink haired middle aged men at audio venues.
Off topic alarm!!!!!! BC327 and BC337 are lower noise than the BC550, BC560 etc but still the latter are very often chosen in low noise designs. Go figure. I suspect if we start debating that painting your hair pink will give a better sound experience and we persevere in spreading the truth we'll see pink haired middle aged men at audio venues.
Nobody can know what was intended.
It sure can "work". At very low supply voltage we use small bias. The 1.8Meg grid resistor adds a bit of gridleak bias. The first peak of a transient will add more bias for the duration of that note. And this is inside a NFB loop with excess gain of like 900 (forward gain ~~1000, closed loop gain 1.2), so even many-% THD open-loop will be fraction-% THD with the NFB loop closed.
Sorry, here I draw the line. The truth is that blue hair gives way better sound experience. Now all I have to do is find out if that's because my hair was pink before, or that one can go from "au naturelle" to blue at once.
;-)
I counted on thumbs, and my dog helped. Yes, try OLG near 60.
Still, with closed-loop gain near zero, even at 60V supply, it can get 3V peak output at near 0.3%THD, and 0.02% at lower levels. It's not an amazing performer, but it don't stink. (Even with the zero-bias 2nd stage.)
Where do you know it from? At least the ONSemi BC337 datasheet doesn't give any noise figures. Anyway, I'm quite astonished about fT = 210 MHz.
Best regards!