Hi All,
I've been rolling an idea in my head of separating the pre amp and the power amp section by adding a small torodial transformer to my Exposure 3010S integrated amplifier that will "push" only the pre amp stage in the integrated amp.
The torodial transformer in the 3010S rated as 400VA and my idea is to add a smaller (60-80VA torodial transformer) transformer.
Is there any real benefit in doing this?
How do you think it will affect the amplifier soundwise?
Thanks
I've been rolling an idea in my head of separating the pre amp and the power amp section by adding a small torodial transformer to my Exposure 3010S integrated amplifier that will "push" only the pre amp stage in the integrated amp.
The torodial transformer in the 3010S rated as 400VA and my idea is to add a smaller (60-80VA torodial transformer) transformer.
Is there any real benefit in doing this?
How do you think it will affect the amplifier soundwise?
Thanks
Peavey runs their front end op amps by resistor dropping from the main rail voltage, followed by a zener parallel to speaker ground as regulator. A bit of energy loss, but a potential source of hum and buzz left out. See for example PV-1.3k on eserviceinfo.com or PV-4c. Also leaves out a lot of weight. These do have thermo controlled fans.
Do you have a schematic? If you don't use phono, it would make more difference to bypass the entire preamp, and use a 10k volume control before the power amp. Easier, too.
Last edited:
I appreciate your answer but can you write it again please in a very simple language😱
I don't want to separate them completely(pre amp-power amp), I still intend to use the Integrated as an Integrated, I just want to add a smaller transformer that will push the pre amp stage separately from the main transformer.
Last edited:
> I just want to add a smaller transformer that will push the pre amp stage separately from the main transformer.
Why??
The power stage eats hundreds of Watts. The preamp less than a dozen.
Say I have a horse and a hamster. The horse eats a hundred pounds a week. The hamster a dozen. I don't make two trips. The hamster chow can ride in a corner of the truck bed full of horse-food.
Why??
The power stage eats hundreds of Watts. The preamp less than a dozen.
Say I have a horse and a hamster. The horse eats a hundred pounds a week. The hamster a dozen. I don't make two trips. The hamster chow can ride in a corner of the truck bed full of horse-food.
Download the PV-1.3k schematic from eserviceinfo.com. View it with a pdf viewer, which I got from irs.gov if it is not part of the operating system now.
Look at page 1, block 3,0 on the left. Resistor R100 drops the voltage from the 85 v rail, zener diode cr100 regulates it to 16 v, capacitor C100 smooths it out. Out the bottom comes 16v for op amps. Look at block 3,A on the right. Resistor R228 reduces the -85 volt rail, zener diode CR216 regulates it to -16 v, capacitor C210 smooths it out. There is the +- 16 volt for their op amps in the front end. A little energy wasted in the resistors, but not probably as much as a separate core loss from a separate 120 vac transformer would cause. You calculate the resistor value to the power rating of the zener diode, burn about 1/2 of the current used by the load op amps idling in the diode. You can get zener diodes up to 5 watts, or above that voltage regulator IC's. The IC's need 2 capacitors, one in, one out, that's why they don't always use them.
After all an op amp like RC4560 is only about 6 ma idle. Peavey put a separate winding for op amp voltage in the MMA-875T, but that is a mixer with about 50 op amp IC's. With that many it is worth the expense for another winding, bridge rectifier, +- filter caps.
Last edited:
I wasn't thinking about gaining more power from the power amp section in the 3010S ( anyway the power delivery to each transformer output is limited by it's own winding and not the quantity of the transformer consumers connected to the transfomer on a different output), I was thinking about "cleaner" power to the pre amp stage.
To be honest I got this idea from a Roksan Caspian integrated amplifier which uses a 350VA transformer for the power amp section and a smaller 60VA transformer for the pre amp section in the integrated.
I assume that there is some kind of interferance or any other effect on the following electronics and the sound when both the power amp and pre amp sections pulls power at the same time, especially for the pre amp stage which is more "delicate" and sensitive with the low level signals that runs through it compare to the power amp section signals.
Naim audio and Cyrus doing the same by giving the customer a choice of adding an external power supply to their amplifiers.
Last edited:
They only thing you can hope to gain from a dedicated preamp transformer is efficiency, really - and only if the main transformer does not include dedicated lower-voltage taps (as they often do - I can't really tell here) but rather uses voltage droppers along the lines of what indianajo was describing. These can be quite spectacularly inefficient (in a higher-power PA amp you might be regulating down from +/-90 V to +/-15 V), but on the other hand it may not be such a big deal if all you have to supply is a few 4558s.
Now let's say you wanted to use the thing as a pure preamp while being able to turn off the power amp section - that would be a different story. The preamp section could probably run on a 20VA transformer, with idle power consumption cut down to a quarter or even less.
Now let's say you wanted to use the thing as a pure preamp while being able to turn off the power amp section - that would be a different story. The preamp section could probably run on a 20VA transformer, with idle power consumption cut down to a quarter or even less.
Well... both the integrated amp and the CD player appear to be IEC Class I devices. If they knew what they were doing, they left the audio ground floating. If they were like most boutique hi-fi builders, they didn't. Easy enough to check with a multimeter (test for continuity between audio ground and protective earth on the mains plug).
PS Audio applied this design feature, starting with their Elite and Elite+ integrated amplifiers which came out in the late 1970's. These amps also located the preamp and power amp transformers to a separate chassis, ostensibly to reduce the effects of any inductively coupled signals that could find their way into the pre and power amps's signal paths.
Personally, I don't think such problems would be manifesting as long as proper engineering and construction principles are adhered to in any audio design and build.
On the other hand, the separate transformer approach, again if properly implemented, can't hurt either, with the exception of added cost to manufacture.
Since you are not modding your equipment to a price point, this is essentially moot.
The separately powered and switched idea for pre and power sections, made by a previous poster, is a great idea with real, tangible advantage. I sometimes use the preamp and/or power section of my PS Elite (Non-Plus) Integrated amp separately, with other equipment. Why have a big power amp PSU idling for no reason if the preamp stage is all you are using?
I think if you do go forward (I most likely would) with this project, the subjects of proper grounding of the new power supply with respect to the existing circuitry, as well as the prevention of turn-on transients produced at the preamp outputs should be considered in the new PSU's topology and integration.
Personally, I don't think such problems would be manifesting as long as proper engineering and construction principles are adhered to in any audio design and build.
On the other hand, the separate transformer approach, again if properly implemented, can't hurt either, with the exception of added cost to manufacture.
Since you are not modding your equipment to a price point, this is essentially moot.
The separately powered and switched idea for pre and power sections, made by a previous poster, is a great idea with real, tangible advantage. I sometimes use the preamp and/or power section of my PS Elite (Non-Plus) Integrated amp separately, with other equipment. Why have a big power amp PSU idling for no reason if the preamp stage is all you are using?
I think if you do go forward (I most likely would) with this project, the subjects of proper grounding of the new power supply with respect to the existing circuitry, as well as the prevention of turn-on transients produced at the preamp outputs should be considered in the new PSU's topology and integration.
If it were my amp and i had the space i would do it in a flash. The subjective sound improvement is substantial even if the front end is opamp based.
You will reach the subjective quality of separates without the drawback of an interconnect cable. I would also experiment with a few different transformers and caps.
Then again, for the majority of members here, this would be a complete waste of time and effort 😎
Thanks all, I'll give it a try, I'll post some photos after I'll get it done.
Do you think a small 20VA tranformer will be enough or shall I go with a bigger 40-80VA transformer?
Do you think a small 20VA tranformer will be enough or shall I go with a bigger 40-80VA transformer?
Electrically the 20VA will most likely be just fine. Hard to say about the sound, especially for a preamp. Larger ones do sound different but not necessarily better. The construction type is also clearly audible: EI, toroid, R-core, C-core. What sounds best is a question of taste and synergy. Unless you have a pile of transformers at hand you better hope you are lucky.
Lots of fans of snubbers here, so perhaps it works for some, but it has failed to eliminate transformer/capacitor/rectifier differences for me.
Lots of fans of snubbers here, so perhaps it works for some, but it has failed to eliminate transformer/capacitor/rectifier differences for me.
Some features in some commercial designs may be present for marketing rather than engineering reasons. This may partly be because audio journalists are rarely up to speed on electronics so can be impressed by something with little or no real advantage.
Depending on the design, not all equipment requires a 3 terminal mains plug.
So to criticize a given piece of equipment because of a "missing" ground at the plug is silly.
Manufacturers must adhere to specific electrical rules for consumer safety, not consumer nitpicking.
I understand that how adding a smaller transformer to push the pre amp stage will affect the sound is a subjective matter, but what is the benfit doing it technically speaking?
Last edited:
Gasp! do you mean that the Hacks could just as likely be reviewing Makeup or writing for the Inquirer.
Regardless, the naive will still suck up 'whatever' as if it were Gospel.
That's seemingly the backbone of the 'information' industry.. currently at least 😉.
- Status
- Not open for further replies.