Booster for 2A3 tube amp
Hi,
I would like to know if it would be appropriate use Zeus as booster of my 2A3 Single ended tube amplifier. By providing the correct load at the input of Zeus, 8 ohms, Zeus as follower should not alter the 2A3 sound. Also with a carefully designed relay when turning off Zeuss can still listen from original 2A3.
So if I need to play some Trance Nation just flick Zeuss on
. I think it's a more Green solution rather then build a 6c33c class A2. I don't like Tube push-pull.
Hi,
I would like to know if it would be appropriate use Zeus as booster of my 2A3 Single ended tube amplifier. By providing the correct load at the input of Zeus, 8 ohms, Zeus as follower should not alter the 2A3 sound. Also with a carefully designed relay when turning off Zeuss can still listen from original 2A3.
So if I need to play some Trance Nation just flick Zeuss on
. I think it's a more Green solution rather then build a 6c33c class A2. I don't like Tube push-pull.
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Zeus is a lovely sounding amp but I think it's bit much expecting that any Hi Fi component will not change the sound . . . .
I suspect that relay contacts in the speaker leads will give a degradation of sound that you will not appreciate - Pioneer researched this years ago, and from this research they decided to removed the headphone socket from some of their amplifiers - particularly the A400 - if they could hear the difference with that, I'm sure you will notice it with your SET.
It is not so elegant but I think swapping the speaker leads will give you the best sound.
Good luck
mike
I suspect that relay contacts in the speaker leads will give a degradation of sound that you will not appreciate - Pioneer researched this years ago, and from this research they decided to removed the headphone socket from some of their amplifiers - particularly the A400 - if they could hear the difference with that, I'm sure you will notice it with your SET.
It is not so elegant but I think swapping the speaker leads will give you the best sound.
Good luck
mike
Thanks Mike for your reply. I agree about the use of relay contacts on audio signal. I cannot avoid though jump connection between SET and Zeus then to speakers. Would it be as bad as relay contacts?
I'm going to build it anyway. 75W Output transformers already done
Well, I think that you will know very soon when you try it
I would suggest . . . .
1) A very good quality rotary switch with good pressure between the contacts and a self cleaning action and if possible multiple contacts in parallel.
2) mercury switches
3) traditional loudspeaker binding posts
My guess is that you will prefer option 3
Personally I prefer a soldered joint to any of these options but I realise that is somewhat inflexible and perhaps totally impractical you your situation.
I would suggest . . . .
1) A very good quality rotary switch with good pressure between the contacts and a self cleaning action and if possible multiple contacts in parallel.
2) mercury switches
3) traditional loudspeaker binding posts
My guess is that you will prefer option 3
Personally I prefer a soldered joint to any of these options but I realise that is somewhat inflexible and perhaps totally impractical you your situation.
Hi,
For this (I am assuming your speakers are reasonably efficient anyway) I would suggest in the first instance that good quality silver pin XLR connectors would be the easiest to get going with.
3 pins ones are normally rated at 5A nominal, and as much as 15A max.
And XLRs are rated for reasonable plug/unplug cycle use too e.g. "Contact Resistance (after 1000 insertions) = 15mΩ max"
Excellent.
If your primaries are about one ohm DC resistance (or a little lower) you can use IXYS to247 package IXTH20N50D depletion mosfets with a ground referenced input phase splitting / step up transformer which will give you auto biasing and an absolute minimalist implementation.
Selecting from a few (12 is probably minimum, better with say 24 pieces - IFAIR a full tube is 30 peices) should give you a couple of well matched pairs.
Pics, progress stories always welcome
Many thanks.
Best wishes,
Susan.
For this (I am assuming your speakers are reasonably efficient anyway) I would suggest in the first instance that good quality silver pin XLR connectors would be the easiest to get going with.
3 pins ones are normally rated at 5A nominal, and as much as 15A max.
And XLRs are rated for reasonable plug/unplug cycle use too e.g. "Contact Resistance (after 1000 insertions) = 15mΩ max"
I'm going to build it anyway. 75W Output transformers already done
Excellent.
If your primaries are about one ohm DC resistance (or a little lower) you can use IXYS to247 package IXTH20N50D depletion mosfets with a ground referenced input phase splitting / step up transformer which will give you auto biasing and an absolute minimalist implementation.
Selecting from a few (12 is probably minimum, better with say 24 pieces - IFAIR a full tube is 30 peices) should give you a couple of well matched pairs.
Pics, progress stories always welcome
Many thanks.
Best wishes,
Susan.
Hi Mike,
You got in first whilst I was composing my reply
I did think of suggesting a nice big wiping silver contact knife switch assembly. Something like that one could make oneself. A real Hammer Horror type prop!
Best wishes,
Susan.
Well, I think that you will know very soon when you try it
I would suggest . . . .
1) A very good quality rotary switch with good pressure between the contacts and a self cleaning action and if possible multiple contacts in parallel.
2) mercury switches
3) traditional loudspeaker binding posts
My guess is that you will prefer option 3
Personally I prefer a soldered joint to any of these options but I realise that is somewhat inflexible and perhaps totally impractical you your situation.
You got in first whilst I was composing my reply
I did think of suggesting a nice big wiping silver contact knife switch assembly. Something like that one could make oneself. A real Hammer Horror type prop!
Best wishes,
Susan.
Hi,
For this (I am assuming your speakers are reasonably efficient anyway) I would suggest in the first instance that good quality silver pin XLR connectors would be the easiest to get going with.
3 pins ones are normally rated at 5A nominal, and as much as 15A max.
And XLRs are rated for reasonable plug/unplug cycle use too e.g. "Contact Resistance (after 1000 insertions) = 15mΩ max"
Excellent.
If your primaries are about one ohm DC resistance (or a little lower) you can use IXYS to247 package IXTH20N50D depletion mosfets with a ground referenced input phase splitting / step up transformer which will give you auto biasing and an absolute minimalist implementation.
Selecting from a few (12 is probably minimum, better with say 24 pieces - IFAIR a full tube is 30 peices) should give you a couple of well matched pairs.
Pics, progress stories always welcome
Many thanks.
Best wishes,
Susan.
Hi Susan!
Thank you so much for helping me out with this integration. I like your brilliant idea of using XLR and I will do so. I completed the 75 transformers following your instructions. I got 1.1/2 M6 laminations under the bed for long time initially for a 6c33c SET project which I reconsidered and now used for Zeus
I've got 98dB efficiency speakers I built connected to my 2A3 SET and I thought to boost the power output with Zeus to improve dynamic response keeping the "2A3 as driver" footprint.
I like the idea of using Depletion mode mosfet but I'm not sure about the sound compared to enhanced mosfet like the STW34NB20 you recommend (Ciss is 2300pF).
With regards to the IXTH20N50D I'm not too sure... I'm worried about the high Ciss 6300pF specified.
It's funny because I've got 2 datasheets of the same part number:
2006 release Ciss Typ 2300pF
2009 release Ciss Typ 6300pF
Regards
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Hi Apelizzo,
Thanks for the info.
Whilst Ciss is specified a bit higher, I have not found it a problem.
The much greater simplicity plus having EVERYTHING ground referenced is a big plus.
The diferences sonically are very small, and I beleive would not cause unhappines.
It is relativly easy to try out both versions, would be interested to have your impressions if you do
My own system uses three IXTH20N50D per channel (pre amp is SE) and has been in almost daily use for something like four years.
Best wishes,
Susan.
P.S. slightly hasty lunchtime at work reply...
Hi Susan!
Thank you so much for helping me out with this integration. I like your brilliant idea of using XLR and I will do so. I completed the 75 transformers following your instructions. I got 1.1/2 M6 laminations under the bed for long time initially for a 6c33c SET project which I reconsidered and now used for Zeus
I've got 98dB efficiency speakers I built connected to my 2A3 SET and I thought to boost the power output with Zeus to improve dynamic response keeping the "2A3 as driver" footprint.
I like the idea of using Depletion mode mosfet but I'm not sure about the sound compared to enhanced mosfet like the STW34NB20 you recommend (Ciss is 2300pF).
With regards to the IXTH20N50D I'm not too sure... I'm worried about the high Ciss 6300pF specified.
It's funny because I've got 2 datasheets of the same part number:
2006 release Ciss Typ 2300pF
2009 release Ciss Typ 6300pF
Regards
Thanks for the info.
Whilst Ciss is specified a bit higher, I have not found it a problem.
The much greater simplicity plus having EVERYTHING ground referenced is a big plus.
The diferences sonically are very small, and I beleive would not cause unhappines.
It is relativly easy to try out both versions, would be interested to have your impressions if you do
My own system uses three IXTH20N50D per channel (pre amp is SE) and has been in almost daily use for something like four years.
Best wishes,
Susan.
P.S. slightly hasty lunchtime at work reply...
Hi Apelizzo,
Thanks for the info.
Whilst Ciss is specified a bit higher, I have not found it a problem.
The much greater simplicity plus having EVERYTHING ground referenced is a big plus.
The diferences sonically are very small, and I beleive would not cause unhappines.
It is relativly easy to try out both versions, would be interested to have your impressions if you do
My own system uses three IXTH20N50D per channel (pre amp is SE) and has been in almost daily use for something like four years.
Best wishes,
Susan.
P.S. slightly hasty lunchtime at work reply...
I would like to try IXTH20N50Ds but it's hard to get them
I just missed a Buy group on forum. Also I already bought the STs from RS. I think I will try the STs first then when I get the chance to buy the IXTH20N50D I will be able to compare them.
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Hi Apelizzo,
Future Electronics is showing them as available from one piece, although you would need more that four to get the two matched pairs.
IXYS | IXTH20N50D | IXTH Series Single N-Channel 500 V 330 mOhm 400 W Power Mosfet - TO-247 AD - Future Electronics
Although they aren't showing any stock...
... IXYS website however shows it as an active part.
Anyway, the ST parts will work well too. I do recommend using a third mosfet per pair for the tracking bias scheme.
Best wishes,
Susan.
I would like to try IXTH20N50Ds but it's hard to get them
I just missed a Buy group on forum. Also I already bought the STs from RS. I think I will try the STs first then when I get the chance to buy the IXTH20N50D I will be able to compare them.
Future Electronics is showing them as available from one piece, although you would need more that four to get the two matched pairs.
IXYS | IXTH20N50D | IXTH Series Single N-Channel 500 V 330 mOhm 400 W Power Mosfet - TO-247 AD - Future Electronics
Although they aren't showing any stock...
... IXYS website however shows it as an active part.
Anyway, the ST parts will work well too. I do recommend using a third mosfet per pair for the tracking bias scheme.
Best wishes,
Susan.
Hi Mike,
Hope you are keeping well.
Thanks.
I do like the idea of the knife switch though, it would be very steam punk
Best wishes,
Susan.
Hope you are keeping well.
Hi Susan, nice to see you here.
Your idea, as usual, is simple, practical & sensible
( the XLR plug one
Thanks.
I do like the idea of the knife switch though, it would be very steam punk
Best wishes,
Susan.
Hi Patrick,
Okay, thanks.
I don't seem to have had a lot of time for audio recently (have a day job), but still trying to wedge in the odd moment to keep things moving.
I will be going along to the 128th AES convention this weekend, since it is in London this time (just down the road for me).
How are you?
Best wishes,
Susan.
Okay, thanks.
I don't seem to have had a lot of time for audio recently (have a day job), but still trying to wedge in the odd moment to keep things moving.
I will be going along to the 128th AES convention this weekend, since it is in London this time (just down the road for me).
How are you?
Best wishes,
Susan.
Thanks For The Memory!
Aaaah! That's awesome! With good transformers, such an amp performs delightfully well and is exquisitely simple! Here's one I built in 1983 using bi-polar transistors in Darlington, with power transformer iron, multi-filar wound. It sounds amazing good, considering how crude it is! Have to get it out of that dead, rustbucket Caddy and fire it up one more time!
*Aprox. 120 W X 2, Idles under 500ma, Draws 26 A, peak, heavily driven.
As requested a seperate thread on transformer based solid state amplifers.
The schematic:
... and what it looks like in practise ...
Everything to the right is power supply, and everything from the middle is amplifier.
See: Zero Feedback Transformer Audio Power Amplifier for more details.
This amplifier is based on Impedance Amplification and has similar distortion characteristics to valve triode designs.
It is relativly easy to build and only has one twiddle pot to set the bias level. The pic shows a monoblock which I built nearly ten years ago and it has not needed adjustment since.
Best wishes,
Susan.
P.S. Yes, it does work.
Aaaah! That's awesome! With good transformers, such an amp performs delightfully well and is exquisitely simple! Here's one I built in 1983 using bi-polar transistors in Darlington, with power transformer iron, multi-filar wound. It sounds amazing good, considering how crude it is! Have to get it out of that dead, rustbucket Caddy and fire it up one more time!
*Aprox. 120 W X 2, Idles under 500ma, Draws 26 A, peak, heavily driven.
Attachments
This was a bit of awake-up call. I've had a partially assembled Zueus sitting in my basement for some time now. I planned to use toroidal power transformers for both stages. Maybe it's time to take the design all the way to completion. BTW, to my knowledge, no one has dragged a Zeus-type amplifier to the Burning Amp festival in San Francisco as of yet. Perhaps it's time to change that, too.