If you spend more for a bigger output transformer for a SE amp, what do you get, other than more bass?
I am currently listening to an SE 6V6 amp with the cheapest Edcor output transformers and there is plenty of bass for me. Do the more expensive transformers sound better overall, or is it all about bass?
I am currently listening to an SE 6V6 amp with the cheapest Edcor output transformers and there is plenty of bass for me. Do the more expensive transformers sound better overall, or is it all about bass?
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A bigger transformer can be better in all aspects, but it depends on how the transformer is made. A bigger poorly made transformer will be worse than a smaller high quality transformer within reason.
If you want high quality sound, and you don't want to spend a ton of money on big iron, parafeed is your friend.
I recently built a parafeed 6V6 amp using a Musical Power Supplies OPT's which had special ordered as stacked for parafeed, i.e. no air gap, and some Bottlehead plate chokes. It has good detail and the -3dB points at 1W are below 20Hz and about6 60kHz with quite smooth rolloffs. The MPS outputs are about $50 ea, so relatively inexpensive and not super large.
John
John
Single Ended Parafeed:
For a Parafeed amplifier, the output transformer is important, but it does have a very easy task, versus a traditional SE output transformer.
The often forgotten fact about a Parafeed amplifier is that the Plate Choke needs to be Very High Quality.
Chokes that are not up to the task for Parafeed service, may have low frequency roll-off, saturation even at low signal levels, bass distortion, intermodulation distortion, and may even have high frequency rolloff.
You might have to spend more on the choke than on the output transformer.
Your Mileage May Vary
Traditional Single Ended:
The single ended output transformer can be Very important. It does have to work with quiescent DC current; but there are many issues:
SE output transformers that are not up to the task, may have low frequency roll-off, saturation even at low signal levels, bass distortion, intermodulation distortion, and may even have high frequency rolloff.
Your Mileage May Vary
For a Parafeed amplifier, the output transformer is important, but it does have a very easy task, versus a traditional SE output transformer.
The often forgotten fact about a Parafeed amplifier is that the Plate Choke needs to be Very High Quality.
Chokes that are not up to the task for Parafeed service, may have low frequency roll-off, saturation even at low signal levels, bass distortion, intermodulation distortion, and may even have high frequency rolloff.
You might have to spend more on the choke than on the output transformer.
Your Mileage May Vary
Traditional Single Ended:
The single ended output transformer can be Very important. It does have to work with quiescent DC current; but there are many issues:
SE output transformers that are not up to the task, may have low frequency roll-off, saturation even at low signal levels, bass distortion, intermodulation distortion, and may even have high frequency rolloff.
Your Mileage May Vary
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A bigger hole in your wallet. You need deeper bass? Use an SS subwoofer and you're golden. There are no benefits in having tubes work the bottom 1-2 octaves. Everything else is for elf ears.
Looking for better bass with SE amp? I use Shunt regulator in the 300B SE amp cathode circuit instead of RC self-bias. It improves a lot in the bass definition and sound much more powerful.
Comparing the CXSE5 and GXSE10 transformers from Edcor, I find the GXSE10 has better HF in addition to better bass compared to the CXSE5. So, the GXSE10 sound better overall to me as well as my (adult) kids whom I have built amps for.
Some important output transformer characteristics to consider:
Bass (most often mentioned) requires high Inductance, and large dimensions (weight) of laminations
Highs (honorable mention) requires low leakage inductance, and low distributed capacitance
Insertion Loss (low, or else . . .)
An output transformer with 0.5 dB insertion loss: Takes 10 Watts from the output tube, but you only get 8.9 Watts to the loudspeaker.
You have to "Pay For What You Get".
Just my opinions
Bass (most often mentioned) requires high Inductance, and large dimensions (weight) of laminations
Highs (honorable mention) requires low leakage inductance, and low distributed capacitance
Insertion Loss (low, or else . . .)
An output transformer with 0.5 dB insertion loss: Takes 10 Watts from the output tube, but you only get 8.9 Watts to the loudspeaker.
You have to "Pay For What You Get".
Just my opinions
As 6A3 says, you pay for what you get. Not always but there are very few good small cheap output transformers but the more you pay usually the more mass you get and that mass is your friend. Especially on a low powered amp watch insertion loss as it robs the few watts you have!
As always you get what you pay for. Stack laminated cores are ok for power transformers but for hifi output transformers high b cut c core construction gives you better everything.look at monolith magnetics, hashimoto, tango all use cut c cores. Spend the money and enjoy the sound.
The Lundahl LL1620 is a great transformer. I can't speak for the standard version, but the 40mA amorphous core model is amazing in a 45 amp. Big bass, and very detailed without fatigue.
In terms of value, it is hard to beat the open frame Edcors. I've used the 10w and 15W models, in a Tubelab SE and SSE, respectively.
In terms of value, it is hard to beat the open frame Edcors. I've used the 10w and 15W models, in a Tubelab SE and SSE, respectively.
Can someone point me to a schematic for a EL84 SE parafeed amp for speakers? Can't find one. I will need to know what plate choke and output coupling capacitor to use and a recommended output transformer impedance.
There are many schematic available.
But, the approach is wrong.
Trioded tube or not, estimated power (selection of choke), estimated anode current (selection of choke), expected LF bandwidth (choke induction, OPT primary induction, capacitor selection), expected power (selection of OPT) .... etc.
But, the approach is wrong.
Trioded tube or not, estimated power (selection of choke), estimated anode current (selection of choke), expected LF bandwidth (choke induction, OPT primary induction, capacitor selection), expected power (selection of OPT) .... etc.
markw51,
Can you tell us something about the rest of your system?
That might, or might not, indicate an EL84 SE parafeed amplifier to be capable of having enough power, etc.
Your system:
Loudspeaker model and efficiency?
Room Size?
Listening in the room at a distance, Or near field listening?
(right now, I am listening at my computer, the speaker is abut 2-1/2 feet away).
Kind of music you listen too (hard rock, small jazz group, chamber music, etc.)
I see EL84 SE amplifier schematics.
I do not see parafeed EL84 SE schematics.
You want a parafeed EL84 SE amplifier because ______________ ?
You do not want a traditional output transformer EL84 SE amplifier because ___________?
For a Parafeed EL84 SE amplifier, there are limiting factors.
Either Pentode or Triode wired (Ultra Linear would require Lots of extra circuitry, because the choke is not tapped; and don't try this with series chokes).
Because of the choke reactances (L and C) the coupling cap reactance, and the output transformer's reactances, global negative feedback is not practical (my opinion)
Triode wired and no negative feedback (damping factor might be 1.5 to 4).
Pentode mode and no negative feedback (damping factor is much less than 1, less than Unity).
Schade negative feedback would be from the choke, not from the output transformer primary (not practical, my opinion).
Don't give up on your search for [another?] amplifier, but be sure of what you will build next.
Can you tell us something about the rest of your system?
That might, or might not, indicate an EL84 SE parafeed amplifier to be capable of having enough power, etc.
Your system:
Loudspeaker model and efficiency?
Room Size?
Listening in the room at a distance, Or near field listening?
(right now, I am listening at my computer, the speaker is abut 2-1/2 feet away).
Kind of music you listen too (hard rock, small jazz group, chamber music, etc.)
I see EL84 SE amplifier schematics.
I do not see parafeed EL84 SE schematics.
You want a parafeed EL84 SE amplifier because ______________ ?
You do not want a traditional output transformer EL84 SE amplifier because ___________?
For a Parafeed EL84 SE amplifier, there are limiting factors.
Either Pentode or Triode wired (Ultra Linear would require Lots of extra circuitry, because the choke is not tapped; and don't try this with series chokes).
Because of the choke reactances (L and C) the coupling cap reactance, and the output transformer's reactances, global negative feedback is not practical (my opinion)
Triode wired and no negative feedback (damping factor might be 1.5 to 4).
Pentode mode and no negative feedback (damping factor is much less than 1, less than Unity).
Schade negative feedback would be from the choke, not from the output transformer primary (not practical, my opinion).
Don't give up on your search for [another?] amplifier, but be sure of what you will build next.
All valid questions and points 2A3.
If you look at the beginning of this thread my question pertained to SE output transformers and I got a lot of comments about using parafeed if I don't want to spend a lot of $ on output transformers so that's why I asked about finding a parafeed circuit since it is the cat's meow to some apparently.
I am currently using a 6V6 SE DIY amp I built using inexpensive 10 watt Edcor SE output transformers and am quite satisfied with it especially in UL mode. I added a switch to switch between UL and triode and I enjoy UL more.
Anyway to answer your questions:
Speakers are Klipsch Forte 1 with 98 db sensitivity so no problem there. I have no problem at all using a traditional output transformer. Just want to make sure I'm not missing out on some kind of parafeed magic before I start drilling holes in a chassis.
Based on your information concerning negative feedback in a parafeed amp it sounds beyond my ability to assemble a great parafeed amp without a lot of frustration. My next project will be an EL84 SE amp since I have the tubes for it. I already have a couple of Edcor guitar amp transformers. Not great for hifi but let's see how they sound.
If you look at the beginning of this thread my question pertained to SE output transformers and I got a lot of comments about using parafeed if I don't want to spend a lot of $ on output transformers so that's why I asked about finding a parafeed circuit since it is the cat's meow to some apparently.
I am currently using a 6V6 SE DIY amp I built using inexpensive 10 watt Edcor SE output transformers and am quite satisfied with it especially in UL mode. I added a switch to switch between UL and triode and I enjoy UL more.
Anyway to answer your questions:
Speakers are Klipsch Forte 1 with 98 db sensitivity so no problem there. I have no problem at all using a traditional output transformer. Just want to make sure I'm not missing out on some kind of parafeed magic before I start drilling holes in a chassis.
Based on your information concerning negative feedback in a parafeed amp it sounds beyond my ability to assemble a great parafeed amp without a lot of frustration. My next project will be an EL84 SE amp since I have the tubes for it. I already have a couple of Edcor guitar amp transformers. Not great for hifi but let's see how they sound.
