Dynaco'ed
Hi navin
Wow, you got a power tranny guy!? Yes, HV winding insulation. In combination with the filament windings your talking one big heavy, hot xfrmr. I would still have three separate units as I stated earlier. Will make your life much easier. My power transformer measures approx. 12cm x 10cm x 9.5cm and weighs tons. A large power transformer supplying around 20A @6.3VAC would produce one heck of a field around it! And tubes being high impedance devices are susceptible to these fields. Besides it's best to keep PS coupling of the different amps, pre-amps to a minimum. Plus as an added bonus it will be easier to make upgrades/modifications to any of the separate amps. Also much easier to lift without the use of a fork-truck!
And as for 20A pwr trannys for a sand (SS) amp, the SS amp is not drawing 20A continuosly (at least it shouldn't be!), whereas the filaments of the tubes will be drawing this current at all times, so even a well built 20A tranny will be HOT!
No not 2 6SN7's, just 1. You would replace the 6U8 triode section, which is a cathodyne/concerta/split-load phase splitter with BOTH units/sections of a single 6SN7 which is a TWIN triode (it has two identical sections/units as does a ECC88, 81, 82, 83, 85 etc.) in a LTP configuration.
Yes you could do that and it will work well. It was used in Dynaco amplifiers using a 6AN8 and the 7199 in some amps, in place of the 6U8/EF82. There is plenty of gain there, 775mV input IIRC will give full output. So you don't need any extra gain in the amp itself. And why Dynaco used the 6AN8 (doesn't sound good IMO) I'll never understand, they must have gotten a really good deal on a large supply of them. But there weren't many tubes that would replace them, pin-wise, but as for the 6U8/EF82 there are much more. Dozens! And as for the 7199 none to speak of really.
Are you thinking of the crossover and placing it inside the amp(s)? You can do that. Put the "LO" crossover in the "LO' amp and the "HI" crossover in the "HI" amp. Unless you provide a means for switching it out, you're committed. In others words you couldn't use either amp as a "straight" amp unless you flipped her over and whip out your soldering iron!
But still I would go with the three box/chassis design. If you need extra gain place it in the crossover box. And if you need to drive long interconnects from the crossover to amp, buy low cap cables and maybe (shudder) add a good cathode follower and/or Frank's 12B4 line-stage to the crossover unit!
Cheers
Wayne
Edit: Maybe xfrmr coupled output! Just a thought!
Hi navin
Wow, you got a power tranny guy!? Yes, HV winding insulation. In combination with the filament windings your talking one big heavy, hot xfrmr. I would still have three separate units as I stated earlier. Will make your life much easier. My power transformer measures approx. 12cm x 10cm x 9.5cm and weighs tons. A large power transformer supplying around 20A @6.3VAC would produce one heck of a field around it! And tubes being high impedance devices are susceptible to these fields. Besides it's best to keep PS coupling of the different amps, pre-amps to a minimum. Plus as an added bonus it will be easier to make upgrades/modifications to any of the separate amps. Also much easier to lift without the use of a fork-truck!
And as for 20A pwr trannys for a sand (SS) amp, the SS amp is not drawing 20A continuosly (at least it shouldn't be!), whereas the filaments of the tubes will be drawing this current at all times, so even a well built 20A tranny will be HOT!
No not 2 6SN7's, just 1. You would replace the 6U8 triode section, which is a cathodyne/concerta/split-load phase splitter with BOTH units/sections of a single 6SN7 which is a TWIN triode (it has two identical sections/units as does a ECC88, 81, 82, 83, 85 etc.) in a LTP configuration.
Yes you could do that and it will work well. It was used in Dynaco amplifiers using a 6AN8 and the 7199 in some amps, in place of the 6U8/EF82. There is plenty of gain there, 775mV input IIRC will give full output. So you don't need any extra gain in the amp itself. And why Dynaco used the 6AN8 (doesn't sound good IMO) I'll never understand, they must have gotten a really good deal on a large supply of them. But there weren't many tubes that would replace them, pin-wise, but as for the 6U8/EF82 there are much more. Dozens! And as for the 7199 none to speak of really.
Are you thinking of the crossover and placing it inside the amp(s)? You can do that. Put the "LO" crossover in the "LO' amp and the "HI" crossover in the "HI" amp. Unless you provide a means for switching it out, you're committed. In others words you couldn't use either amp as a "straight" amp unless you flipped her over and whip out your soldering iron!
But still I would go with the three box/chassis design. If you need extra gain place it in the crossover box. And if you need to drive long interconnects from the crossover to amp, buy low cap cables and maybe (shudder) add a good cathode follower and/or Frank's 12B4 line-stage to the crossover unit!
Cheers
Wayne
Edit: Maybe xfrmr coupled output! Just a thought!
I have a transformer winding guy on my doorstep. He designs the power, I the output stuff. Should I consider myself blessed? Down here one does not only have postage to consider but also a rather uninspiring exchange rate. Imports of the inductive kind would cost double+ the cost of local construction.
Wayne, me guy, what is this about old creaking bones? You youngsters are moaning at an early age these days! I thought (being ignorant from afar) Hillbillies were only in Arkansas. Spent a pleasant time in Fayetteville and surroundings for a week+ in 1988 - congress, etc.
I would agree with Wayne regarding construction, that there comes a time to consider separates. Somewhat in the same boat, I have just completed a 2 x 100W (only! - 8 x 6L6GC) job for someone, and that was somewhat massive (about 24 Kg) and on the border of what should have been separates, or at least monoblocks. After boasting earlier on another thread that I never experienced induction problems (particularly with the L of an LC PS filter), I did have some this time, which I was fortunate to have been able to cancel with a nifty little circuit. Compact sure looks nice, but can cause tears afterwards.
Regards.
Wayne, me guy, what is this about old creaking bones? You youngsters are moaning at an early age these days!
I thought (being ignorant from afar) Hillbillies were only in Arkansas. Spent a pleasant time in Fayetteville and surroundings for a week+ in 1988 - congress, etc.I would agree with Wayne regarding construction, that there comes a time to consider separates. Somewhat in the same boat, I have just completed a 2 x 100W (only! - 8 x 6L6GC) job for someone, and that was somewhat massive (about 24 Kg) and on the border of what should have been separates, or at least monoblocks. After boasting earlier on another thread that I never experienced induction problems (particularly with the L of an LC PS filter), I did have some this time, which I was fortunate to have been able to cancel with a nifty little circuit. Compact sure looks nice, but can cause tears afterwards.
Regards.
Re: Dynaco'ed
your 12cm x 10cm x 9.5cm transformer should weigh about 5.5kg (12lbs). I knoew there was a catch to the tube transformers. continuous current is very different from occasoinal current peak.
I think you have got me convinced to use 3 power trannys. one for each set of 4 EL34 and one for the ECC88 and 6SN7etc. Now how lond a wire can the EF82 drive? what about the 6SN7? can i split the amp so tha tthe 8 EL34 are in 2 seperate boxes (4 + 4)?
since my design skills in tubes is extremely limited i now am trying to deide beteen the ckt you posted and the EICO HIF 87 (repalcing the ECC83 with ECC88) . I have not heard good things about the 7199.
keeping my less = more principle in mind...
EICO = 8 tubes. 2 ECC88, 2 6SN7, 4 EL34 per channel
Your ckt = 6 tubes. 1 ECC88, 1 EF82, 4 EL34 per channel. how big is the EF82?
cogsncogs said:
your 12cm x 10cm x 9.5cm transformer should weigh about 5.5kg (12lbs). I knoew there was a catch to the tube transformers. continuous current is very different from occasoinal current peak.
I think you have got me convinced to use 3 power trannys. one for each set of 4 EL34 and one for the ECC88 and 6SN7etc. Now how lond a wire can the EF82 drive? what about the 6SN7? can i split the amp so tha tthe 8 EL34 are in 2 seperate boxes (4 + 4)?
since my design skills in tubes is extremely limited i now am trying to deide beteen the ckt you posted and the EICO HIF 87 (repalcing the ECC83 with ECC88) . I have not heard good things about the 7199.
keeping my less = more principle in mind...
EICO = 8 tubes. 2 ECC88, 2 6SN7, 4 EL34 per channel
Your ckt = 6 tubes. 1 ECC88, 1 EF82, 4 EL34 per channel. how big is the EF82?
Re: Dynaco'ed
1. how long a cable can i have using the 6SN7 or EF82? How far away can my power amps be using Belden interconnects.
2. this amp will be dedicated to driving the 18W8546 push push and 2905-9900 based speaker so i am going to avoid the switch. I will leave a note in the amp telling me what to bypass if I ever need to use the amp fullrange.
cogsncogs said:
No not 2 6SN7's, just 1. You would replace the 6U8 triode section, which is a cathodyne/concerta/split-load phase splitter with BOTH units/sections of a single 6SN7 which is a TWIN triode (it has two identical sections/units as does a ECC88, 81, 82, 83, 85 etc.) in a LTP configuration.
Yes you could do that and it will work well. It was used in Dynaco amplifiers using a 6AN8 and the 7199 in some amps, in place of the 6U8/EF82.
Are you thinking of the crossover and placing it inside the amp(s)? You can do that. Put the "LO" crossover in the "LO' amp and the "HI" crossover in the "HI" amp. Unless you provide a means for switching it out, you're committed. In others words you couldn't use either amp as a "straight" amp unless you flipped her over and whip out your soldering iron!
But still I would go with the three box/chassis design. If you need extra gain place it in the crossover box. And if you need to drive long interconnects from the crossover to amp, buy low cap cables and maybe (shudder) add a good cathode follower and/or Frank's 12B4 line-stage to the crossover unit!
1. how long a cable can i have using the 6SN7 or EF82? How far away can my power amps be using Belden interconnects.
2. this amp will be dedicated to driving the 18W8546 push push and 2905-9900 based speaker so i am going to avoid the switch. I will leave a note in the amp telling me what to bypass if I ever need to use the amp fullrange.
dont know if i should start another thread for this since the amp has now morphed into a 3 box design.
box 1: Steve Bench's ECC88 crossover and 2 6SN7 for the line stage (or 12B4 or another line stage that can drive 15 m of RCA cable). Low Pass and High Pass line output.
box 2 and 3: 2 6SN7 or ECF82 phase splitter and 4 EL34 and 2 OPTs. Low Pass and High Pass speaker output.
Q: what line stage should I use after the ECC88 XO? th 6SN& can have a gain of about 20 while the 12B4 about 5.
Q: I am stuck between the 6SN7 phase splitter used in the HIF 87 and the ECF82 ckt Wayne posted earlier. Any opinions?
Q: Anyone have a link to the final version of Frank's 12B4 line stage. I am a newbie and would like to first use tried and tested ckts.
box 1: Steve Bench's ECC88 crossover and 2 6SN7 for the line stage (or 12B4 or another line stage that can drive 15 m of RCA cable). Low Pass and High Pass line output.
box 2 and 3: 2 6SN7 or ECF82 phase splitter and 4 EL34 and 2 OPTs. Low Pass and High Pass speaker output.
Q: what line stage should I use after the ECC88 XO? th 6SN& can have a gain of about 20 while the 12B4 about 5.
Q: I am stuck between the 6SN7 phase splitter used in the HIF 87 and the ECF82 ckt Wayne posted earlier. Any opinions?
Q: Anyone have a link to the final version of Frank's 12B4 line stage. I am a newbie and would like to first use tried and tested ckts.
@navin
Some would prefer an ECC88 driving a 6SN7 LTP driving a pair of EL34's. In that configuration the output would clip before the LTP, which supplies more than enough drive. Others would prefer the 6U8/EF82 for it's simplicity. A pair of EL34's is known for being easy to drive. And if you've read the thread:
www.diyaudio.com/forums/showthread.php?s=&threadid=40609&highlight=
You will notice the unequal plate/cathodeload resistors of the 6U8 triode unit. This I believe is due to some peculiar charactristics of the output transformers. You can read about in the thread. I have read some articles and one old thread here, as to why the bottom EL34 needed more drive than the upper EL34, but I can't seem to locate any of these at the moment. But with a good or other OPT's equal resistors would probably be used in most cases. I had an old BELL 6060 stereo intergrated amp that used a 12AX7/ECC83 amp/concerta phase splitter with equal plate/cathode resistors driving the output stage. I will email you the schemantic. It's too large to post here, unless I cut it up in sections. When I get my web site up and running...!
It is about the same size of an ECC88, 9 pin, 9AE basing.
Go to Frank's Electron tube pages and do a search for 6U8:
www.tubedata.info/
My suggestions:
'LO' amp:
1x ECC88 AF Amp (1/2 each for Left/Right)
2x 6SN7 LTP/Splitter (1 tube each) for Left/Right)
4x EL34 AF Output PP UL Configuration (2 each for Left/Right)
'HI' amp:
1x ECC88 AF Amp (1/2 each for Left/Right)
2x 6SN7 LTP/Splitter (1 tube each) for Left/Right)
4x EL34 AF Output PP Triode configuration (2 each for Left/Right)
Crossover:
2x ECC88 (1 tube Hi pass, Lo pass for each channel Left/Right)
A good linestage (we're talking 4 stages of line level amplification here) for a 'little' extra gain plus/with a LOW output impedance and low noise for each channel Left/Right placed after the crossover stage, with the Volume/Level control placed 'between' the XO and the linestage. The level pots (4) placed at that position will allow individual adjustment of the the Hi/Lo outputs for each channel, Hi-lo adjustment for the left cahnnel, Hi-Lo adjustment for the left channel.
You could use a balance adjustment pot (dual ganged control, one section reversed connected for either the Hi or Lo, so that would need to be a 'linear taper' pot, or a very hard to find audio/log taper pot made for just such an application i.e. one section having a reverse log taper) for HI-Lo for each channel and a 'Master' level (dual ganged) audio/log taper control for both channels. That would reduce the controls to three. Dual ganged would mean a 'stereo' pot. And If you wanted to you could add a Left/Right balance control, but I've found with most sources it's really not necessary in most all cases. A balance adjustment pot for the HI-Lo outputs are necessary for each channel. As you would need to balance the HI-LO for each speaker.
Three separate units. Does this make sense?
What you would end up with doing it this way would be:
1 nice 35-40W Class AB1 PP UL Amp.
1 nice 15-20W Class A or AB1 PP triode amp.
1 nice crossover/linestage unit.
Hope this helps
Wayne
P.S. If you need more gain in your individual amps you could use many other tubes for the 1st stage (AF Amp) to put in front of the 6SN7 LTP, like a 12AT7/ECC81, 6AQ8/ECC85 and lots of others depending on what's available where you live.
Some would prefer an ECC88 driving a 6SN7 LTP driving a pair of EL34's. In that configuration the output would clip before the LTP, which supplies more than enough drive. Others would prefer the 6U8/EF82 for it's simplicity. A pair of EL34's is known for being easy to drive. And if you've read the thread:
www.diyaudio.com/forums/showthread.php?s=&threadid=40609&highlight=
You will notice the unequal plate/cathodeload resistors of the 6U8 triode unit. This I believe is due to some peculiar charactristics of the output transformers. You can read about in the thread. I have read some articles and one old thread here, as to why the bottom EL34 needed more drive than the upper EL34, but I can't seem to locate any of these at the moment. But with a good or other OPT's equal resistors would probably be used in most cases. I had an old BELL 6060 stereo intergrated amp that used a 12AX7/ECC83 amp/concerta phase splitter with equal plate/cathode resistors driving the output stage. I will email you the schemantic. It's too large to post here, unless I cut it up in sections. When I get my web site up and running...!
It is about the same size of an ECC88, 9 pin, 9AE basing.
Go to Frank's Electron tube pages and do a search for 6U8:
www.tubedata.info/
My suggestions:
'LO' amp:
1x ECC88 AF Amp (1/2 each for Left/Right)
2x 6SN7 LTP/Splitter (1 tube each) for Left/Right)
4x EL34 AF Output PP UL Configuration (2 each for Left/Right)
'HI' amp:
1x ECC88 AF Amp (1/2 each for Left/Right)
2x 6SN7 LTP/Splitter (1 tube each) for Left/Right)
4x EL34 AF Output PP Triode configuration (2 each for Left/Right)
Crossover:
2x ECC88 (1 tube Hi pass, Lo pass for each channel Left/Right)
A good linestage (we're talking 4 stages of line level amplification here) for a 'little' extra gain plus/with a LOW output impedance and low noise for each channel Left/Right placed after the crossover stage, with the Volume/Level control placed 'between' the XO and the linestage. The level pots (4) placed at that position will allow individual adjustment of the the Hi/Lo outputs for each channel, Hi-lo adjustment for the left cahnnel, Hi-Lo adjustment for the left channel.
You could use a balance adjustment pot (dual ganged control, one section reversed connected for either the Hi or Lo, so that would need to be a 'linear taper' pot, or a very hard to find audio/log taper pot made for just such an application i.e. one section having a reverse log taper) for HI-Lo for each channel and a 'Master' level (dual ganged) audio/log taper control for both channels. That would reduce the controls to three. Dual ganged would mean a 'stereo' pot. And If you wanted to you could add a Left/Right balance control, but I've found with most sources it's really not necessary in most all cases. A balance adjustment pot for the HI-Lo outputs are necessary for each channel. As you would need to balance the HI-LO for each speaker.
Three separate units. Does this make sense?
What you would end up with doing it this way would be:
1 nice 35-40W Class AB1 PP UL Amp.
1 nice 15-20W Class A or AB1 PP triode amp.
1 nice crossover/linestage unit.
Hope this helps
Wayne
P.S. If you need more gain in your individual amps you could use many other tubes for the 1st stage (AF Amp) to put in front of the 6SN7 LTP, like a 12AT7/ECC81, 6AQ8/ECC85 and lots of others depending on what's available where you live.
cogsncogs said:
Some would prefer an ECC88 driving a 6SN7 LTP driving a pair of EL34's.
You will notice the unequal plate/cathodeload resistors of the 6U8 triode unit. This I believe is due to some peculiar charactristics of the output transformers. You can read about in the thread....I will email you the schemantic. It's too large to post here, unless I cut it up in sections. When I get my web site up and running...!
My suggestions:
'LO' amp:
1x ECC88 AF Amp (1/2 each for Left/Right)
2x 6SN7 LTP/Splitter (1 tube each) for Left/Right)
4x EL34 AF Output PP UL Configuration (2 each for Left/Right)
'HI' amp:
1x ECC88 AF Amp (1/2 each for Left/Right)
2x 6SN7 LTP/Splitter (1 tube each) for Left/Right)
4x EL34 AF Output PP Triode configuration (2 each for Left/Right)
Crossover:
2x ECC88 (1 tube Hi pass, Lo pass for each channel Left/Right)
A good linestage (we're talking 4 stages of line level amplification here)...
You could use a balance adjustment pot (dual ganged control, one section reversed connected for either the Hi or Lo, so that would need to be a 'linear taper' pot...and a 'Master' level (dual ganged) audio/log taper control for both channels. That would reduce the controls to three.
Three separate units. Does this make sense?
What you would end up with doing it this way would be:
1 nice 35-40W Class AB1 PP UL Amp.
1 nice 15-20W Class A or AB1 PP triode amp.
1 nice crossover/linestage unit.
Hope this helps
Wayne
P.S. If you need more gain in your individual amps you could use many other tubes for the 1st stage (AF Amp) to put in front of the 6SN7 LTP, like a 12AT7/ECC81, 6AQ8/ECC85 and lots of others depending on what's available where you live.
Wayne, I dont know where i would be without all this input. Sometimes I wonder why you waste your time on numbskulls like me. You can email me at navinadv@yahoo.com.
As far as the unequal resistors are concerned maybe the right way is to use a pot for one (or both) resistor(s) and see what value or ratio of values sound best. Then one can replace the pots with resistors. Easier said that done right?
following my less=more philosophy i am trying to keep parts count down so am hoping to eliminate the AF section of the HI and LO power amps. The gain required could be in the line stage of the crossover hence the thought of using 6SN7 as the line stage (instead of Frank's line stage). Should this even be attempted? Does it make sense? The idea of having more gain the the crossover stage is that the singal going to the power amps will be higher and that might improve the signal / noise ratio of the system.
I think for the Hi-Lo balance a linear (reverse) pot will be just fine.
I was also hoping that if I am using a 3 amp combo I could place the power amps near the speakers. In that case each power amp would have one triode 15W channel and 1 UL/Pentode 35-40W section. Am I asking for too much?
I get the feeling that you keep steering me towards the road of sanity and I keep asking for impossible solutions.
Are you thinking of putting the driver/splitter stage (6SN7) in the xo unit? This will not work because the driver (and that includes the ECC88 AF Amp) must reside in the power amplifier. Reason; global feedback loop (NFB). Almost mandatory in a PP UL amp. But some have built (and they are good amps) PP amps without global feedback, but the OPT requirements are high, and the use of local feedback (nested); but doing as I think you are proposing, the HF stability would be a nightmare! It would also increase the noise to an amount I don't even want to think of.
I will simulate Steve's XO and do an AC Analysis. You may not need any extra gain but you will more than likely need to lower the output impedance through the use of some kind imp. lowering stage. Even adding one or two more tubes to the XO would be easy to do, not hard at all.
I was also hoping that if I am using a 3 amp combo I could place the power amps near the speakers. In that case each power amp would have one triode 15W channel and 1 UL/Pentode 35-40W section. Am I asking for too much?
You could but why? Place the amps in-between the spkrs! Fairly good spkr cables are not that expensive. It will make your connections much easier. It's really hard for me to comment on this as I cannot see your listening room. Don't fall into that "My speaker cables sound better fastened to the wall than lying on the floor/carpet. The carpet slows down the electrons, muffling/smearing the sound!" stuff!
Some audiophiles/phools have more money invested in spkr cables and interconnects than they do in the rest of their equipment. And don't forget the rocks (pulled up from the bottom of Lake Erie!) or bricks on your CD player! I found an old P.A. amplifier buried deep in trash dump; I'm gonna use those well aged carbon comp. resistors! Should make my amp sound real smooth. <rant>
And yes, less is always more. If you can do a job with one stage instead of two, then one is the answer. But can just one do what's being asked of it?
Possibly. But we will know more after I do the simulation. Most good cables have a shunt capacitance of around 75-100pf per meter. I've measured some as high as 360pf per meter i.e. Rat Shack mid-line, the cheaper ones had lower capacitance!
Cheers
Wayne
Edit: Ok, I think I see what you are thinking of. Using another 6SN7 as a linestage? Yes that will work very well.
cogsncogs said:
Are you thinking of putting the driver/splitter stage (6SN7) in the xo unit?
I will simulate Steve's XO and do an AC Analysis. You may not need any extra gain but you will more than likely need to lower the output impedance through the use of some kind imp. lowering stage. Even adding one or two more tubes to the XO would be easy to do, not hard at all.
You could but why? Place the amps in-between the spkrs! .... Don't fall into that "My speaker cables sound better fastened to the wall than lying on the floor/carpet. The carpet slows down the electrons, muffling/smearing the sound!" stuff!
Some audiophiles/phools have more money invested in spkr cables and interconnects than they do in the rest of their equipment.
Possibly. But we will know more after I do the simulation. Most good cables have a shunt capacitance of around 75-100pf per meter. I've measured some as high as 360pf per meter i.e. Rat Shack mid-line, the cheaper ones had lower capacitance!
Ok this is what i am thinking of.
Crossover: ECC88 x 2 (left/right channel) and 6SN7 x 4 (left/right hi/lo) line stage. 1 6SN7 for each of the 4 "channels".
Power amp x 2: 2 6SN7 phase splitter and 4 EL34. the HIF 87 has global feedback coming to the ECC83 but cant we modify that feedback to go to the 6SN7 instead? If not we always have your ECF82/EL34 3 tube power amp ckt to fall back on.
You know what due to the poor availability of the parts in India and my slow speed of making these amps I am starting almost 1 year ahead of when i expect to use the amps. The apt we plan to move into is still not ready and we dont expect to get it before Oct 2006. Such is the speed of things in India.
I intend to start the process of making them as soon as the parts list is finalised and that will only happen after the ckt is finalised.
This amp will be part of my bedroom system and the bedroom wont be more than 210 sq. ft. So space is going to be critical. Since speakers are push push I could hide each power amp behind it's speaker and only have a compact (no OPTs) crossover visible.
I use standard Belden cable for my inteconnects and found them to be smother than atleast a couple of more highly regarded brands. My CD players are a Marantz CD 63Ki and a Phonosopihe and I have a Marantz CD recorder as well. One of the CD players will be part of my room system the other will be mated to a EL84 amp and be part of my son's system (with still undecided fullrange speakers).
As far as less = more is concerned when i built my ScanSpeak 2 way I noticed that as one eliminated some passive XO components the sound got more transparent. I was using 12SWG air core inductors and polyester caps. Also if one places a speaker carefully one can really get decent sound.
When are you next coming to the US - I have pages and pages of schematics for you. The best choice, IMO, would be a solid state front end with the EL 34 output stage. What output transformers will you be using? That is really the key.
I've e-mailed you privately, check your account and please email me privately, off forum.
I've e-mailed you privately, check your account and please email me privately, off forum.
al2002 said:
which address did you email to. my vsnl address is down so i am using navinadv@yahoo.com address till they get it figured out.
my nxt trip to the US will be after we move to the new apt and much after this amp will be built.
SS front end - tube power.
most people I know do this the other way around.The Pentode/UL OPTs are being built in Singapore. The builder just told me he does not know how to build one for a triode output. Now considering he build OPTs for Diva and other Hi end guys in Sing I am surprised. I will be meeting him saturday to figure this out.
I dont think I'd use Hammond and Lundhal is way too expensive so I looking at alternates as well.
Something to consider:
It seems to me that what your building or your earlier concept was something like a ST-70 where you could add an octal plug in to carry the RC crossover filter, and where the output can be switched triode/UL. This would allow you to configure it back to normal stereo if you ever want to use them in a different configuration.
Pete B.
It seems to me that what your building or your earlier concept was something like a ST-70 where you could add an octal plug in to carry the RC crossover filter, and where the output can be switched triode/UL. This would allow you to configure it back to normal stereo if you ever want to use them in a different configuration.
Pete B.
PB2 said:
the way this design has progressed....
1st idea.
large 4 ch power amp with 4 OPTs and common power transformer where the driver tube also acted as a LO pass or HI pass crossover.
next stage...
dedicated tube for the crossover - this added 4 more tubes to the orignal chassis. using steve bench's XO and the HIF 87. by this point everyone was of the opinion that it be atleast a 2 box design with atleast 2 power transformers (1 per channel).
3rd stage....enter Wayne from Wayne and others
3 box design. box 1: LO pass amp, box 2: HI pass amp, box 3: crossover.
this was later configured to...
box 1: Left channel power amp LO Pass and HI Pass
box 2: Right channel power amp, LO Pass and HI Pass
box 3: crossover and line stage.
Wayne also posted an excellent ckt using just 3 tubes per channel (1 EF82 and 2 El34).
now to simplify the signal path I thought of eliminating the AF tube in box 2 and 3 and using a line stage with 20+db of gain to compensate for the gain lost by removing the AF section of the power amp and to drive a RCA cable a longer distance - 10m+. Only the question of how to handle global feedback....here is where we are stuck.
Meanwhile the guy I ordered my OPTs from told me he does not know how to build a OPT for a triode amp. I thought it was jsut a question of the right taps.
PB2 said:
How good is the HIF 87 ckt? Is it preferable over the ckt using the EF82 that Wayne posted? How does one etermine which is a better ckt?
BTW my OPT guys toled me this "I dont know how to make a OPT for Triode my OPT has a standard 5 wire input and is used in UL mode" How does one wire an OPT in Triode and Pentode.
Navin, that sounds funny. Depending on the required impedance, you simply ignore the screen taps. Primary impedance for triodes is usually some 20 - 30% higher than for UL, but the difference in sound is not that noticable. Note that some amplifiers provide the option to switch between triodes and UL using the same output transformer.
cogsncogs said:
Ok here are the choices...
Crossover:
2 x ECC88C (Steve bench design) octal
http://members.aol.com/sbench101/Crossover/xover.gif
Line stage: 4x 6SN7 nonal
http://www.tubebuilder.com/images/schematics/preamps/6sn7_sig.gif
Power amp:
4x ECF82, 8x EL34 (wayne posted it earlier) ECF82 is nonal
4 6SN7, 8x EL34 (Steve Bench) http://members.aol.com/sbench102/PowerAmps/e34lamp.gif
or
http://www.tubebuilder.com/images/schematics/pushpull/6146_a.gif
2x ECC88 AF, 4x 6SN7 Phase Splitter, 8x EL34 (modified HIF87)
the power amp will be divided into 2 power amps.
seems that i will end up using the following combination of tubes.
octal tubes....4x ECC88, 8 EL34
nonal tubes....8 x 6SN7
the crossover will have 2 x ECC88 and 4 x 6SN7 and each power amp will have 1 x ECC88, 2 x 6SN7 and 4 x EL34.
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