Hi
I didn't say anything about ultra linear.Only CFB in pentode mode with G2 about 100Vand more lower than Va.Try it!
I think beginners do such things us taking the 16 ohm winding to do a CFB.
With what kind of OPT you have a frequency responce more than 20hz to 20khz in an SE mode?
Please read this very nice article.
http://www.cortmi.com.ua/Omak/OmakFrame.htm
Sayonara
I didn't say anything about ultra linear.Only CFB in pentode mode with G2 about 100Vand more lower than Va.Try it!
I think beginners do such things us taking the 16 ohm winding to do a CFB.
With what kind of OPT you have a frequency responce more than 20hz to 20khz in an SE mode?
Please read this very nice article.
http://www.cortmi.com.ua/Omak/OmakFrame.htm
Sayonara
Konnichiwa,
No, I did.
Well, Mr. Byrith will be delighted to know that.
http://www.lundahl.se/claus_b_se.html
I know also of at least one very well reviewed commercial SE Amp employing the same kind of scheme.
Any competently designed one? Tango/Iso (many models), S&B various OEM, Lundahlk, Plitron come immediatly to mind. There are a few others not readily available that offer very good performance.
Why? It perpetuates several patently untrue claims and is in many places based preconceived notions that are simply untrue when observed closely.
My last SE Amplifier was well flat in the 10Hz-50KHz band (into a resistive load) and was tuned to be so by suitable use of compensation between stages. Even wider HF bandwidth (>> 100KHz) is quite trivial to realise in SE but of no real benefit as such, unless recordings and transducers improve drastically.
Sayonara
GAK said:
No, I did.
GAK said:
Well, Mr. Byrith will be delighted to know that.
http://www.lundahl.se/claus_b_se.html
I know also of at least one very well reviewed commercial SE Amp employing the same kind of scheme.
GAK said:
Any competently designed one? Tango/Iso (many models), S&B various OEM, Lundahlk, Plitron come immediatly to mind. There are a few others not readily available that offer very good performance.
GAK said:
Why? It perpetuates several patently untrue claims and is in many places based preconceived notions that are simply untrue when observed closely.
My last SE Amplifier was well flat in the 10Hz-50KHz band (into a resistive load) and was tuned to be so by suitable use of compensation between stages. Even wider HF bandwidth (>> 100KHz) is quite trivial to realise in SE but of no real benefit as such, unless recordings and transducers improve drastically.
Sayonara
Sorry but with CFB I mean something like this.
http://www.quadesl.com/schematics/quad2.gif
Kuei:NOT current feedback through secondary.
Layberithius:Or NFB from the 16 ohm tap.
Anyway this forum is for helping someone to build a nice SE 300B amp.Why we are wasting our time to prove things out of this forum.
I only gave an idea with the CFB.I'm taking it back OK?
http://www.quadesl.com/schematics/quad2.gif
Kuei:NOT current feedback through secondary.
Layberithius:Or NFB from the 16 ohm tap.
Anyway this forum is for helping someone to build a nice SE 300B amp.Why we are wasting our time to prove things out of this forum.
I only gave an idea with the CFB.I'm taking it back OK?
Actually, GAK, the Byrith design could be considered voltage derived, voltage injected cathode feedback.
This mode of operation (LM3, I've heard it referred to as), exploits the fact that the DC resistance of a secondary winding is so low that the bias current of a valve will not develop a sufficient DC offset to harm the speaker, and puts the secondary in series with the cathode, giving voltage feedback by shifting the cathode, while the grid remains at the same potential.
Have you tried it? Or, for that matter, tried analyzing it?
Apparently, it gives decent results. The Lundahl design has less than 1 ohm output resistance with a single-ended EL34 design. One supposes other pentodes could go significantly lower.
This mode of operation (LM3, I've heard it referred to as), exploits the fact that the DC resistance of a secondary winding is so low that the bias current of a valve will not develop a sufficient DC offset to harm the speaker, and puts the secondary in series with the cathode, giving voltage feedback by shifting the cathode, while the grid remains at the same potential.
Have you tried it? Or, for that matter, tried analyzing it?
Apparently, it gives decent results. The Lundahl design has less than 1 ohm output resistance with a single-ended EL34 design. One supposes other pentodes could go significantly lower.
Frank,
Any chance of getting you to post a design using the 3CX300A1? That might be a decent alternative to the 300B.
As I recall, it's mu is under 10, and the plate resistance is about 2/3 that of the 300B. At the same time, it can dissipate almost as much by itself, and more than 5 times as much if forced convection is used.
Any chance of getting you to post a design using the 3CX300A1? That might be a decent alternative to the 300B.
As I recall, it's mu is under 10, and the plate resistance is about 2/3 that of the 300B. At the same time, it can dissipate almost as much by itself, and more than 5 times as much if forced convection is used.
Well, I'm by no means an EE...
Anyway, having dug up the sheet, I find that it has a mu of 9, Rp of 450, and a plate dissipation of 300W. Max DC plate voltage is 1800V, and max DC current is 470mA. Heater is reasonable, at 6.3V and 2.65A..
More importantly, it has no more than about 25pF input capacitance, which works out to about 200pF miller, right?
Now, unless the onset of grid current is very early, you should not need an amp to drive this thing. You just need a bit of current to drive it, or sufficient local feedback in the driver stage.
The example stats for a single ended amp with 5% distortion at 15W show a grid drive requirement of 120Vp-p, which is easily met by most drivers. That example uses 500V plate (similar to the 300B), and a bias of 80mA (typically used with 300B).
Finding the correct operating point, using high plate voltages, I would think you should be able to operate this in class A1 for a single ended output of 50W or so, right?
With that amount of power, you can use a 5K:8 transformer, and achieve a damping factor of about 10 without negative feedback, provided the secondary has a sufficiently low impedance.
Where is the problem? (With regards to driving it, I mean) It's probably right there in my face, but I can't see it at this time of night. (5:30am)
You sure you aren't talking about the umpteen kilowatt transmitter tubes that bear similar designations?
Anyway, having dug up the sheet, I find that it has a mu of 9, Rp of 450, and a plate dissipation of 300W. Max DC plate voltage is 1800V, and max DC current is 470mA. Heater is reasonable, at 6.3V and 2.65A..
More importantly, it has no more than about 25pF input capacitance, which works out to about 200pF miller, right?
Now, unless the onset of grid current is very early, you should not need an amp to drive this thing. You just need a bit of current to drive it, or sufficient local feedback in the driver stage.
The example stats for a single ended amp with 5% distortion at 15W show a grid drive requirement of 120Vp-p, which is easily met by most drivers. That example uses 500V plate (similar to the 300B), and a bias of 80mA (typically used with 300B).
Finding the correct operating point, using high plate voltages, I would think you should be able to operate this in class A1 for a single ended output of 50W or so, right?
With that amount of power, you can use a 5K:8 transformer, and achieve a damping factor of about 10 without negative feedback, provided the secondary has a sufficiently low impedance.
Where is the problem? (With regards to driving it, I mean) It's probably right there in my face, but I can't see it at this time of night. (5:30am)
You sure you aren't talking about the umpteen kilowatt transmitter tubes that bear similar designations?
Input capacity
Angel, I think you estimated the miller capacity a little too high. Of course better to over estimate the caps than under estimate.
By far the most capacity from the grid 1 is to cathode. So maybe 45 to 60pf miller caps seems about right, give or take a few caps, plus the cap from G1 to cathode.
Cheers.
Angel, I think you estimated the miller capacity a little too high. Of course better to over estimate the caps than under estimate.
By far the most capacity from the grid 1 is to cathode. So maybe 45 to 60pf miller caps seems about right, give or take a few caps, plus the cap from G1 to cathode.
Cheers.
Re: Hmmm
Konnichiwa,
You have repeatedly made this statement, without actually naming any such amplifier specifically. May I ask you to name exatcly which Amplifiers these where and if they are "ordinary" commercial ones? Many commercial 300B Amplifiers are indeed severely coloured, as a direct result of their design. I would think that these colorations are deliberatly introduced to give what the designer thinks will "sound good".
Have you listened to the Kondo/Audio Note Japan Baransu 300B SE Amplifier? Or one of the Loesch/Wiesner ones? Or maybe the Wavac EC300B or the later Le Maison de l'Audiophile 300B with teh Valve regulated supply and EL84 driver designed by JC Verdier (also made with small changes by JC Verdier)? Or have you heard the 2-Stage version of the Broderpatrol 300B SE Amplifier? All these are known to me and all these sound exceptionally uncoloured, realistic and outperform almost ANYTHING else I have previously come across.
Have you ever yourself build as experiment one of your amplifiers using 300B Outputs? It might be an interesting thing to do.
It should be easy to fit one of your KT88 SE Amplifiers with suitable Valve sockets. It is important to pay attention to the heater supply of the 300B, my minimum recommendation is schottky rectified DC, filtered with 4,700uF low ESR filter capacitance per 300B (if the amp uses fixed bias one 6.3V Heater winding with Schottky rectification and 10,00uF can supply both 300B's) followed by a heavy duty common mode choke and suitable further further filtering using Sanyo Os-Con's and a LM1085 or LT1085 adjustable regulator supported by Os-Con's to supply the 5V DC heater.
If self bias is used two seperate heater circuits are required of course. In each case the signal current return should be taken either froman artificial centertap or from the negative side of the heater. Please note that how well the heatersupply is realised contributes probably at least 30 - 40% of the total sonic result with directly heated valves and most commercial amplifiers do not do it well enough AT ALL.
As drivers use a pair of russian 6S45 Driver Valves, operated at around 180V Anode Voltage and 10mA current and a constant current source or Choke as anode load. I'd think a DN2540 depletion type Mosfet would make a fine CCS with a total supply of 360V to the driverstage though chokes sound better. The CCS or choke will insulate the Driverstage quite well from Supply fluctuations, however it's probably worthwhile using a pair of 1K filter resistors with each at least 22uF to further decouple the driverstage +B if no seperate powersource is used.
For the 300B grid coupling use 0.1uF & 510k if the valves operate self bias (with a 1k//6k8 cathode resistor) and 0.47uF/100k if fixed grid bias is used. If you pay enough attention to your 300B Amplifier as described above you may very well find the same as I found, namely that no EL34 or KT88 comes even close. Of course, if you FUBAR the amplifier design then you have a bad amplifer, but don't go blaming the output valve in that case.
Sayonara
Konnichiwa,
Positron said:
You have repeatedly made this statement, without actually naming any such amplifier specifically. May I ask you to name exatcly which Amplifiers these where and if they are "ordinary" commercial ones? Many commercial 300B Amplifiers are indeed severely coloured, as a direct result of their design. I would think that these colorations are deliberatly introduced to give what the designer thinks will "sound good".
Have you listened to the Kondo/Audio Note Japan Baransu 300B SE Amplifier? Or one of the Loesch/Wiesner ones? Or maybe the Wavac EC300B or the later Le Maison de l'Audiophile 300B with teh Valve regulated supply and EL84 driver designed by JC Verdier (also made with small changes by JC Verdier)? Or have you heard the 2-Stage version of the Broderpatrol 300B SE Amplifier? All these are known to me and all these sound exceptionally uncoloured, realistic and outperform almost ANYTHING else I have previously come across.
Have you ever yourself build as experiment one of your amplifiers using 300B Outputs? It might be an interesting thing to do.
It should be easy to fit one of your KT88 SE Amplifiers with suitable Valve sockets. It is important to pay attention to the heater supply of the 300B, my minimum recommendation is schottky rectified DC, filtered with 4,700uF low ESR filter capacitance per 300B (if the amp uses fixed bias one 6.3V Heater winding with Schottky rectification and 10,00uF can supply both 300B's) followed by a heavy duty common mode choke and suitable further further filtering using Sanyo Os-Con's and a LM1085 or LT1085 adjustable regulator supported by Os-Con's to supply the 5V DC heater.
If self bias is used two seperate heater circuits are required of course. In each case the signal current return should be taken either froman artificial centertap or from the negative side of the heater. Please note that how well the heatersupply is realised contributes probably at least 30 - 40% of the total sonic result with directly heated valves and most commercial amplifiers do not do it well enough AT ALL.
As drivers use a pair of russian 6S45 Driver Valves, operated at around 180V Anode Voltage and 10mA current and a constant current source or Choke as anode load. I'd think a DN2540 depletion type Mosfet would make a fine CCS with a total supply of 360V to the driverstage though chokes sound better. The CCS or choke will insulate the Driverstage quite well from Supply fluctuations, however it's probably worthwhile using a pair of 1K filter resistors with each at least 22uF to further decouple the driverstage +B if no seperate powersource is used.
For the 300B grid coupling use 0.1uF & 510k if the valves operate self bias (with a 1k//6k8 cathode resistor) and 0.47uF/100k if fixed grid bias is used. If you pay enough attention to your 300B Amplifier as described above you may very well find the same as I found, namely that no EL34 or KT88 comes even close. Of course, if you FUBAR the amplifier design then you have a bad amplifer, but don't go blaming the output valve in that case.
Sayonara
Konnichiwa,
I am very familiar with the Quad Schematic (and the amplifier).
However, whall we agree that feedback is feedback, regardless if applied to cathode or grid?
A larger degree of cathode feedback from a seperate cathode winding or a lower degree of cathode feedback from the speaker winding with further (Ultralinear) feedback to the screengrid will give pretty much the same result, given a sufficiently well designed output transformer and of course the application of the same overall degree of feedback in both cases.
So, no matter if you use CFB or LM3, the results (measured and sonic) will be similar if not almost identical.
Sayonara
GAK said:
I am very familiar with the Quad Schematic (and the amplifier).
However, whall we agree that feedback is feedback, regardless if applied to cathode or grid?
A larger degree of cathode feedback from a seperate cathode winding or a lower degree of cathode feedback from the speaker winding with further (Ultralinear) feedback to the screengrid will give pretty much the same result, given a sufficiently well designed output transformer and of course the application of the same overall degree of feedback in both cases.
So, no matter if you use CFB or LM3, the results (measured and sonic) will be similar if not almost identical.
Sayonara
Konnichiwa,
I take it you are familiar with this Amp?
http://tec-sol.com/3CX300A1_amp_english.htm
But note the 3CX300A1 is made only by Svetlana and no other source exists and also that it is a modified industrial Valve manufacturerd on the request of Svetlana US, now disappeared from the scene. So while it MAY look interetsing it's issues are the same as the SV572-XX and SV811-XX Valves with respect to availability etc.
Note that without forced air cooling this valve has only 30W dissipation and more importantly, it's metal shell is the Anode (Shock risk).
Good thing it's IDH and you can use AC, it would not as easy to provide such a heatersupply with low noise in DC.
What is listed there is a "lumped" capacitance, inlcuding Grid/Cathode etc. I think it would be best to meaure the Cag yourself and then calculate the Milleramplified capacitance..
Sayonara
I take it you are familiar with this Amp?
http://tec-sol.com/3CX300A1_amp_english.htm
An externally hosted image should be here but it was not working when we last tested it.
But note the 3CX300A1 is made only by Svetlana and no other source exists and also that it is a modified industrial Valve manufacturerd on the request of Svetlana US, now disappeared from the scene. So while it MAY look interetsing it's issues are the same as the SV572-XX and SV811-XX Valves with respect to availability etc.
angel said:
Note that without forced air cooling this valve has only 30W dissipation and more importantly, it's metal shell is the Anode (Shock risk).
angel said:
Good thing it's IDH and you can use AC, it would not as easy to provide such a heatersupply with low noise in DC.
angel said:
What is listed there is a "lumped" capacitance, inlcuding Grid/Cathode etc. I think it would be best to meaure the Cag yourself and then calculate the Milleramplified capacitance..
Sayonara
Just wanted to say that this thread is very informative and helpful especially thanks to the untiring efforts of TL and others of course. SETs may look easy to build but getting the best out of them is a whole other deal.
I am thinking of going the SET route but I am not totally convinced yet that it will be worth the very high cost of building a good 300B amp. I think the amp I might build might cost well into the 4000-5000 euro range to be satisfactory.I am not going to spend that money unless I am certain that it is seriously going to outperform my maxed out battery powered gainclone (which replaced the more expensive Aleph 5 monoblocks). I will probably have to audition a good one to know but there are almost none here in Ireland.
I am thinking of going the SET route but I am not totally convinced yet that it will be worth the very high cost of building a good 300B amp. I think the amp I might build might cost well into the 4000-5000 euro range to be satisfactory.I am not going to spend that money unless I am certain that it is seriously going to outperform my maxed out battery powered gainclone (which replaced the more expensive Aleph 5 monoblocks). I will probably have to audition a good one to know but there are almost none here in Ireland.
A good 300b need not cost anywhere in that zone.
Most important stuff is Power transformer, chokes, psu caps and output transformers.
Which would cost you €505 for the transformers..and 300b's are included in that price.
(His latest c-cores are very good) 0,05mm laminations.
http://www.ae-europe.nl/trafosets_engels.htm
€400 for some Black gates...
€1000 for the rest... and voila.
Cheers,
Bas
Konnichiwa,
Yes, it is very easy to "throw together" a 2A3 or 300B SE Amplifier that will make pleasant noises, but few could be considered particulary "good" in an absolute sense. If ou want to get the best possible from a DHT you need to pay a lot of attention, as much in fact as in any other case.
I suggest that it is WELL worth it. Go for it. Honest.
It is not THAT expensive.
Let's take a view at how I would suggest to build a set of Monoblocks from scratch, using "known good" parts, with a view to later upgrades of the Output Transformer to maybe a pair of $ 1,000 the pair Japanese exotes with Amorphous or Nickel Permally Cores.
I would build using the Hammond 1628SE Output if the highest power Valve would be a normal 300B with 2A3, 45 & 10/10Y Options and the 1627SE if I'd be using any of these "Arnold Governegger" 300B's on Steroids....
That will set you back around $ 200 per pair of Amp's from parts Express, there is a hammond distribution in the UK who charge fairly.
Suitable Anode Load chokes for the driverstage need not cost a fortune either, check with Brian Cherry on the S&B ones, they will work fine for a Driverstage using a high transconductance triode at 10 - 12mA, let's allow $100 each too for a shrouded version that can be mounted on top of a chassis, okay?
That is $ 200 for the Audio Iron per amp.
Now the Powersupply.
Using the 230V equivalent of the Hammond 273BX will do fine for the 300B section of the Amplifier if it is aimed primarily at 300B's. It has a winding for the Rectifier heater, a 6.3V winding that can be rectified to feed the 300B and just the right HT to cover a "fixed Bias" 300B at "high power" operating points. For a wider range of output valves (by changing the input capacitor value) use the 230V version of the 272JX and the 230V version of the 274BX or 278X for "Super 300B" Valves. The driverstage I would give a 270HX, again it has all windings needed. With two big PSU Transformers at around $ 60 each we have another $ 120 per amplifier.
Hammond has nice enclosed filter chokes which should work okay with a low value input capacitor for around $ 30 - 40 each, we will be wanting a total of 4pcs, 2 pcs 193C for the driverstage and 2 pcs 193J for the powerstage unless "Super 300B's" are used, in that case drop in the 193M which costs more. The chokes for the Amplifier will thus set us back around $ 150 per amplifier.
Next we need PSU capacitors, I can get 50uF metal can enclosed Film Capacitors with suitable AC ratings (Motor Run rated 500V AC and thus 700V DC) for under $ 20 each from all major suppliers, we will use up 6pcs of these is another $ 120 per amplifier.
Let us allow $ 100 for a really solid and elaborate Amplifier Plate from Schaeffer Aparatebau and for the wood used on the frame and we have the main passive components pegged down as:
Chassis: $ 100
PSU Caps: $ 120
PSU Chokes:$ 150
PSU TX's: $ 120
Audio TX's: $ 200
So per monoblock Amplifier $ 700 should give us the chassis, the iron and the main PSU Capacitors, so $ 1400 for the pair.
Valves, sockets and a few other parts can vary widely in cost, but IF we accept my "usual suspects" then you will buy a pair of TJ Mesh Anode globes as Outputs, two pairs of TJ 274A/B as rectifiers and a pair of Sovtek 6S45 as Drivers, from DIY HiFisupply you get the lot for around $ 700 from DIY HiFisupply.
As the whole amplifier I would recommend (stacked supplies, directcoupled, chokeloaded driver) is pretty much "parts less" apart from those listed above such a "piece de resistance" with virtually ALL areas maxed out for performance would set you back well below $ 2,500 US.
For that you get an amplifier the likes of which are not made commercially and if you switch to using the ISO/Tango TC-160-15W Anode Load choke for the driver and the ISO/Tango FC-30-3.5S as Output Transformer (I'd keep the rest Hammond) for a total of < $ 1,000 for the Audio Iron you have something that will be exceptional by anyones standards for around $ 3,000 in parts.
I personally think those around 3K American would be well worth it for a pair of monoblocks of that kind of build and design.
If you wanted instead "cheap" (by comparison) you could build a variant of the DRD Amplifier by Jack Elliano. With Hammond Iron (1628SE, 274BX using "hybrid bridge" rectifier, 2 X 193J Choke and a suitable Anode Choke, 3pcs 50uF Motor Run Cap) you could build these paying around $ 1,500 in parts per pair of monoblocks including chassis, TJ Rectifier & Output valve and Sovtek 6S45PE Driver, all Film Cap PSU with CLCLC filtering, in itself a mightily serious Amp I'd say.
So, decide just how far you want to go in lunacy and then build.
Sayonara
protos said:
Yes, it is very easy to "throw together" a 2A3 or 300B SE Amplifier that will make pleasant noises, but few could be considered particulary "good" in an absolute sense. If ou want to get the best possible from a DHT you need to pay a lot of attention, as much in fact as in any other case.
protos said:
I suggest that it is WELL worth it. Go for it. Honest.
It is not THAT expensive.
Let's take a view at how I would suggest to build a set of Monoblocks from scratch, using "known good" parts, with a view to later upgrades of the Output Transformer to maybe a pair of $ 1,000 the pair Japanese exotes with Amorphous or Nickel Permally Cores.
I would build using the Hammond 1628SE Output if the highest power Valve would be a normal 300B with 2A3, 45 & 10/10Y Options and the 1627SE if I'd be using any of these "Arnold Governegger" 300B's on Steroids....
That will set you back around $ 200 per pair of Amp's from parts Express, there is a hammond distribution in the UK who charge fairly.
Suitable Anode Load chokes for the driverstage need not cost a fortune either, check with Brian Cherry on the S&B ones, they will work fine for a Driverstage using a high transconductance triode at 10 - 12mA, let's allow $100 each too for a shrouded version that can be mounted on top of a chassis, okay?
That is $ 200 for the Audio Iron per amp.
Now the Powersupply.
Using the 230V equivalent of the Hammond 273BX will do fine for the 300B section of the Amplifier if it is aimed primarily at 300B's. It has a winding for the Rectifier heater, a 6.3V winding that can be rectified to feed the 300B and just the right HT to cover a "fixed Bias" 300B at "high power" operating points. For a wider range of output valves (by changing the input capacitor value) use the 230V version of the 272JX and the 230V version of the 274BX or 278X for "Super 300B" Valves. The driverstage I would give a 270HX, again it has all windings needed. With two big PSU Transformers at around $ 60 each we have another $ 120 per amplifier.
Hammond has nice enclosed filter chokes which should work okay with a low value input capacitor for around $ 30 - 40 each, we will be wanting a total of 4pcs, 2 pcs 193C for the driverstage and 2 pcs 193J for the powerstage unless "Super 300B's" are used, in that case drop in the 193M which costs more. The chokes for the Amplifier will thus set us back around $ 150 per amplifier.
Next we need PSU capacitors, I can get 50uF metal can enclosed Film Capacitors with suitable AC ratings (Motor Run rated 500V AC and thus 700V DC) for under $ 20 each from all major suppliers, we will use up 6pcs of these is another $ 120 per amplifier.
Let us allow $ 100 for a really solid and elaborate Amplifier Plate from Schaeffer Aparatebau and for the wood used on the frame and we have the main passive components pegged down as:
Chassis: $ 100
PSU Caps: $ 120
PSU Chokes:$ 150
PSU TX's: $ 120
Audio TX's: $ 200
So per monoblock Amplifier $ 700 should give us the chassis, the iron and the main PSU Capacitors, so $ 1400 for the pair.
Valves, sockets and a few other parts can vary widely in cost, but IF we accept my "usual suspects" then you will buy a pair of TJ Mesh Anode globes as Outputs, two pairs of TJ 274A/B as rectifiers and a pair of Sovtek 6S45 as Drivers, from DIY HiFisupply you get the lot for around $ 700 from DIY HiFisupply.
As the whole amplifier I would recommend (stacked supplies, directcoupled, chokeloaded driver) is pretty much "parts less" apart from those listed above such a "piece de resistance" with virtually ALL areas maxed out for performance would set you back well below $ 2,500 US.
For that you get an amplifier the likes of which are not made commercially and if you switch to using the ISO/Tango TC-160-15W Anode Load choke for the driver and the ISO/Tango FC-30-3.5S as Output Transformer (I'd keep the rest Hammond) for a total of < $ 1,000 for the Audio Iron you have something that will be exceptional by anyones standards for around $ 3,000 in parts.
I personally think those around 3K American would be well worth it for a pair of monoblocks of that kind of build and design.
If you wanted instead "cheap" (by comparison) you could build a variant of the DRD Amplifier by Jack Elliano. With Hammond Iron (1628SE, 274BX using "hybrid bridge" rectifier, 2 X 193J Choke and a suitable Anode Choke, 3pcs 50uF Motor Run Cap) you could build these paying around $ 1,500 in parts per pair of monoblocks including chassis, TJ Rectifier & Output valve and Sovtek 6S45PE Driver, all Film Cap PSU with CLCLC filtering, in itself a mightily serious Amp I'd say.
So, decide just how far you want to go in lunacy and then build.
Sayonara
More mistakes Thorsten?
Thorsten,
First, I don't mean to be mean. But when one preaches but doesn't know what he/they are talking about, alot of people are going to get hurt. Afterall, they work hard for their money and want to spend it wisely.
".. Many commercial 300B Amplifiers are indeed severely coloured, as a direct result of their design. I would think that these colorations are deliberatly introduced to give what the designer thinks will "sound good".
Have you listened to the Kondo/Audio Note Japan Baransu 300B SE Amplifier? Or one of the Loesch/Wiesner ones? Or maybe the Wavac EC300B or the later Le Maison de l'Audiophile 300B with teh Valve regulated supply and EL84 driver designed by JC Verdier (also made with small changes by JC Verdier)? Or have you heard the 2-Stage version of the Broderpatrol 300B SE Amplifier? All these are known to me and all these sound exceptionally uncoloured, realistic and outperform almost ANYTHING else I have previously come across."
Well if the colorations induced, then you just convicted the brands that showed at the CES and THE Show. Yes I heard all of what was there, some of what you said and some not. Of course you also haven't heard all the KT88 designs out there either, but that never stopped you from condemning the tube.
Read on.
You have 2 years, maybe3 in tube design, and before that proaudio?
"For the 300B grid coupling use 0.1uF & 510k if the valves operate self bias (with a 1k//6k8 cathode resistor) and 0.47uF/100k if fixed grid bias is used. If you pay enough attention to your 300B Amplifier as described above you may very well find the same as I found, namely that no EL34 or KT88 comes even close. Of course, if you FUBAR the amplifier design then you have a bad amplifer, but don't go blaming the output valve in that case." You just convicted yourself.
So your schematic and "teaching" uses a .15uf cap(your schematic), and above a .1/510k, .47uf /100k if fixed grid bias.
However, even a simple test will confirm that Neither of these designs are even close, Not even close to flat sounding VS a straightwire reference. Way off. So one must color the music to make the 300b sound good?
So besides not checking for parts neutrality, in another string, we see you haven't checked a simple neutral sounding coupling circuit either.
"For the last two years I have had my head deep in triodes and Valves of every kind. Most of my System is DIY."
I don't mean to be mean, but Thorsten these people have worked hard for their money and they don't need someone preaching at us when one can't even design a simple flat response sounding circuit, let alone a complete amp.
Bas, now what are we to believe. First, Thorsten seems to have us spending thousands on an amp and now you say they don't?
Confusion reigns. So what will a particular design sound like?
Thorsten,
First, I don't mean to be mean. But when one preaches but doesn't know what he/they are talking about, alot of people are going to get hurt. Afterall, they work hard for their money and want to spend it wisely.
".. Many commercial 300B Amplifiers are indeed severely coloured, as a direct result of their design. I would think that these colorations are deliberatly introduced to give what the designer thinks will "sound good".
Have you listened to the Kondo/Audio Note Japan Baransu 300B SE Amplifier? Or one of the Loesch/Wiesner ones? Or maybe the Wavac EC300B or the later Le Maison de l'Audiophile 300B with teh Valve regulated supply and EL84 driver designed by JC Verdier (also made with small changes by JC Verdier)? Or have you heard the 2-Stage version of the Broderpatrol 300B SE Amplifier? All these are known to me and all these sound exceptionally uncoloured, realistic and outperform almost ANYTHING else I have previously come across."
Well if the colorations induced, then you just convicted the brands that showed at the CES and THE Show. Yes I heard all of what was there, some of what you said and some not. Of course you also haven't heard all the KT88 designs out there either, but that never stopped you from condemning the tube.
Read on.
You have 2 years, maybe3 in tube design, and before that proaudio?
"For the 300B grid coupling use 0.1uF & 510k if the valves operate self bias (with a 1k//6k8 cathode resistor) and 0.47uF/100k if fixed grid bias is used. If you pay enough attention to your 300B Amplifier as described above you may very well find the same as I found, namely that no EL34 or KT88 comes even close. Of course, if you FUBAR the amplifier design then you have a bad amplifer, but don't go blaming the output valve in that case." You just convicted yourself.
So your schematic and "teaching" uses a .15uf cap(your schematic), and above a .1/510k, .47uf /100k if fixed grid bias.
However, even a simple test will confirm that Neither of these designs are even close, Not even close to flat sounding VS a straightwire reference. Way off. So one must color the music to make the 300b sound good?
So besides not checking for parts neutrality, in another string, we see you haven't checked a simple neutral sounding coupling circuit either.
"For the last two years I have had my head deep in triodes and Valves of every kind. Most of my System is DIY."
I don't mean to be mean, but Thorsten these people have worked hard for their money and they don't need someone preaching at us when one can't even design a simple flat response sounding circuit, let alone a complete amp.
Bas, now what are we to believe. First, Thorsten seems to have us spending thousands on an amp and now you say they don't?
Confusion reigns. So what will a particular design sound like?
Hi,
actually I found thorsten's post quite informative and he makes sense too. The pricing he's related in the above thread seems pretty accurate as I've investigated myself. I'd like Thorsten to keep posting his advice here, and do hope he's not put off by all this negative stuff.
Thanks
Raja
actually I found thorsten's post quite informative and he makes sense too. The pricing he's related in the above thread seems pretty accurate as I've investigated myself. I'd like Thorsten to keep posting his advice here, and do hope he's not put off by all this negative stuff.
Thanks
Raja
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