Hey tube forum!
I've got a very attractive 12x8x2 enclosure that is simply begging for some tubes and blue Edcors sticking out of the top. I'm also in need of a new integrated (downsizing the eyesore stack of commercial stuff).
I've looked at the Simple SE board, but it appears to be just slightly too large for any layout I can figure, taking into account the transformers. I'm not 100% confident in my ability to PTP that circuit either.
Anyone got an idea for a smallish tube integrated, ideally with an available board? My speakers are ~88db-ish sensitivity and 4 ohms (though I'll likely be building new ones at some point soon).
I've got a very attractive 12x8x2 enclosure that is simply begging for some tubes and blue Edcors sticking out of the top. I'm also in need of a new integrated (downsizing the eyesore stack of commercial stuff).
I've looked at the Simple SE board, but it appears to be just slightly too large for any layout I can figure, taking into account the transformers. I'm not 100% confident in my ability to PTP that circuit either.
Anyone got an idea for a smallish tube integrated, ideally with an available board? My speakers are ~88db-ish sensitivity and 4 ohms (though I'll likely be building new ones at some point soon).
You will definitely need new, high efficiency, speakers. You need upwards of 30 WPC, if 88 dB. sensitive speakers are employed.
Contact member Jeff Yourison about the SE 6BM8 project he and I worked on. You have only 2 bottles. It is based on an old Mullard design. Mullard used full pentode mode, but we used UL. I think you can squeeze everything into the little box. The B+ supply is a "full wave" voltage doubler. If push comes to shove, use a "wall wart" for the heater supply and buy some space.
BTW, build an external 300 mA. heater supply and 16BM8/PCL82 tubes with series wired heaters will work NICELY.
Contact member Jeff Yourison about the SE 6BM8 project he and I worked on. You have only 2 bottles. It is based on an old Mullard design. Mullard used full pentode mode, but we used UL. I think you can squeeze everything into the little box. The B+ supply is a "full wave" voltage doubler. If push comes to shove, use a "wall wart" for the heater supply and buy some space.
BTW, build an external 300 mA. heater supply and 16BM8/PCL82 tubes with series wired heaters will work NICELY.
My original SSE, the industrial amp, is built in a chassis that is exactly 12 X 8 X 2 internally, so it can be done. That said, my amp does run quite hot, but it has zero ventilation. There is a closed bottom box and no holes.
The amp is 7 years old and other than the solid state diodes blowing in the first month, there have been no issues. It still has the original EH KT-88's and I run them hot, almost 100 mA per tube. Yes this puts too much load on the Allied power transformer at 220 mA on a 175 ma transformer. It gets too hot to touch after playing all day, but survives.
My speakers are Yamaha NS-10M's rated at 87 or 88 db depending on which paper you read. Will it rock the house...no it won't. However it is plenty loud in my 10 X 11 foot room. Loud enough to get the "turn it down" scream from my wife in the other end of the house.
My OPT's are early Transcendars which do not have UL taps so I run triode for about 7 or 8 WPC. UL will get you about 14 watts with KT88's which is like 3 db more efficient speakers.
My other SSE uses the big Edcors with UL taps and 96 db 15 inch speakers....yes it rocks the house...across the street. And no, there is no way those big OPT's will fit on that chassis.
The amp is 7 years old and other than the solid state diodes blowing in the first month, there have been no issues. It still has the original EH KT-88's and I run them hot, almost 100 mA per tube. Yes this puts too much load on the Allied power transformer at 220 mA on a 175 ma transformer. It gets too hot to touch after playing all day, but survives.
My speakers are Yamaha NS-10M's rated at 87 or 88 db depending on which paper you read. Will it rock the house...no it won't. However it is plenty loud in my 10 X 11 foot room. Loud enough to get the "turn it down" scream from my wife in the other end of the house.
My OPT's are early Transcendars which do not have UL taps so I run triode for about 7 or 8 WPC. UL will get you about 14 watts with KT88's which is like 3 db more efficient speakers.
My other SSE uses the big Edcors with UL taps and 96 db 15 inch speakers....yes it rocks the house...across the street. And no, there is no way those big OPT's will fit on that chassis.
I refuse to listen exclusively to "cans". So, some friction is inevitable. "Women are from Venus. Men are from Mars."
Wow, thanks for the input! Was that original SSE with a board? What are the actual dimensions of the board? I found a template on the forum somewhere, but it may not be 100% accurate.
Perhaps what I need to do is consider other transformer options. I was looking at the GX transformers at Edcor and they're about 3x3 and the power transformer was about 3.2x4.2 (not to mention if I want a choke on top). Here's the power and the OT I looked at. They weren't leaving me enough room without allowing some overlap of the board under the transformers inside the chassis (but maybe that isn't a big issue?).
I've heard so many good things about the SSE that it is my first choice, if I can get it to work.
Perhaps what I need to do is consider other transformer options. I was looking at the GX transformers at Edcor and they're about 3x3 and the power transformer was about 3.2x4.2 (not to mention if I want a choke on top). Here's the power and the OT I looked at. They weren't leaving me enough room without allowing some overlap of the board under the transformers inside the chassis (but maybe that isn't a big issue?).
I've heard so many good things about the SSE that it is my first choice, if I can get it to work.
It is the second or third one I made, but the first one to use the actual mass produced PC board. The first ones used home cooked boards.
The PC board is 5.25 inches by 7.5 inches.
I got the amp out from behind the TV where it has been for about two years. It is rather dusty back there. I use it with this computer and a cheap 10 inch powered subwoofer from Newegg (behind this computer screen facing the corner of the room), since the Yamahas don't go below 80Hz.
Now that I look at it there may be an issue. The internal size of the chassis is 12 X 8 X 2 but the channel aluminum that I used makes the top plate 12 X 9 X 2 and my OPT's hang over the rear edge. These OPT's are 2.75 inches wide and would just fit on a 8 inch deep chassis.
Having the OPT's overlap the board is not an issue. Having the OPT's overlap the output tubes IS. I am not sure your OPT's will fit with KT88's.
I stuffed a Triad C-24X choke under the deck. It's only 1 HY but far better than no choke and no hum is noted on the big speakers. These chokes are far too ugly to display on top, but I did mount a huge motor run cap up there.
Women do not understand why guys NEED 500 watts or 500 horsepower, and guys do not understand the need for 7 pillows on the bed that you can't sleep on or 14 pairs of shoes in the closet that are never worn.......after 29 years of marriage, we just call it a draw. Some things are not meant to be understood. My head sweats too much for "cans" so I try to keep things down when she is home. I'm selling the 500 HP car, but building a 500, no 800 watt tube amp! Kinda hard to hide that one.
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Good news!
I just remeasured the top plate and it is actually 8.25 X 12. In addition, the aluminum channel gives me another 1/2 on either end for a total of 9.25 width on top. Maybe, just maybe, that will leave room for rca's, a switch or two, and a pot.
Will the 350-0-350 transformer I'm looking at limit my tube choice at all? I'm a sq stickler, but could probably use as many watts as are realistically possible.
Thanks to all for the help with this!
I just remeasured the top plate and it is actually 8.25 X 12. In addition, the aluminum channel gives me another 1/2 on either end for a total of 9.25 width on top. Maybe, just maybe, that will leave room for rca's, a switch or two, and a pot.
Will the 350-0-350 transformer I'm looking at limit my tube choice at all? I'm a sq stickler, but could probably use as many watts as are realistically possible.
Thanks to all for the help with this!
Multiply 350 by a conservative 1.2 to get 420. Use a 5AR4 to rectify the B+ and get a bit more. That's plenty for SE KT88s. If you use a 5AR4, install the SS diode tweak, with UF4007s in series with the tube's anodes. The otherwise satisfactory Sovtek 5AR4 needs help in the PIV dept. George will have to state the best way to do this in combination with his board.
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The SSE board was revised about a year ago to include these diodes and a CL140 in the PT CT. These parts were added due to the questionable quality of random batches of 5AR4's from any of todays current vendors. Tube purists can place wire jumpers in the holes for these parts, which makes the revised board exactly like the old board......
Except for the name change. It is now SSE. I can not use the word "simple" and the common abreviation for Single Ended together without getting another letter from the lawyers. There is a trademarked audio product out there with a similar name that is neither simple or single ended. It seems that Googling their name brought up pictures of SSE users proudly displaying the SSE's that they had built instead of the trademarked product.
Ok, one last quick question (hopefully) before I place some orders:
Because I like to fiddle with my stereo, it's entirely likely that I'll want to use 8 ohm speakers at some point in this setup (in fact I have a pair of ported Fostex 8ohm bookshelves somewhere around the house). Currently I'm using 4 ohm speakers though (missed the tweeter and better extension).
Is there a way to spec the OPT from Edcor that it will work satisfactorily well with either 4 or 8 ohm loads? I'm looking at the GXSE15-4-5k. By my understanding, that would work with 8ohm speakers at a reduced output. Is this better than going with a GXSE15-8-5k and suffering increased distortion with the 4 ohm speakers I'm using ATM (i.e. would it be noticeable)? Finally, would a GXSE15-6-5k give me the most flexibility to keep the effective load as close as possible to 3k-5k for either speaker impedance?
With the lead time on these Edcors, I want to make the right decision!
Because I like to fiddle with my stereo, it's entirely likely that I'll want to use 8 ohm speakers at some point in this setup (in fact I have a pair of ported Fostex 8ohm bookshelves somewhere around the house). Currently I'm using 4 ohm speakers though (missed the tweeter and better extension).
Is there a way to spec the OPT from Edcor that it will work satisfactorily well with either 4 or 8 ohm loads? I'm looking at the GXSE15-4-5k. By my understanding, that would work with 8ohm speakers at a reduced output. Is this better than going with a GXSE15-8-5k and suffering increased distortion with the 4 ohm speakers I'm using ATM (i.e. would it be noticeable)? Finally, would a GXSE15-6-5k give me the most flexibility to keep the effective load as close as possible to 3k-5k for either speaker impedance?
With the lead time on these Edcors, I want to make the right decision!
Given that Edcor does not make a multi tapped version of these transformers, yes. This would present a 6666 ohm load to the tube with an 8 ohm speaker, and a 3333 ohm load with a 4 ohm speaker.
I have a 3.5K OPT with 4 and 8 ohm taps. I usually run my "8 ohm" Yamahas on the 4 ohm tap reflecting a 7000 ohm load to the tube, if my speakers were 8 ohms, but for most of the curve, they are 10 ohms or higher. I seem to prefer the tighter bass offered with the lighter load even though it may cost me a watt or two.
You have not discussed your tube choice but a KT88 will work down to 3300 ohms. An EL34 should work that low except if your speakers are actually below 4 ohms in the bass region (unlikely unless they are really big) and you hit them hard with bass. A 6L6GC may strain to deliver crisp bass and may audibly distort into a 3300 ohm load. Loads that are too high improve the damping factor, reduce distortion, but reduce output power. I tend toward preferring this so I usually build 300B amps with 5K OPT's instead of the usual 3600 ohms.
I have both EL34's and 6L6's on hand (mostly cheaper guitar-amp spec for my gigging amps), but I'd like to go with KT88's for this.
Sounds like the 6 ohm tap is a go. In all likelihood, I'll be building/buying new speakers in the future and 8 ohm seems to be the most common impedance. I'll be looking for sensitivity when future shopping/building anyways, so I'm not too concerned about reduced output with the higher load.
Found my Fostex speakers and they're Tekton 4.1's. 8 ohms and 90db, so they'll get a fair shake with the new amp along with the 4 ohm speakers. We'll see who comes out on top. The suspense is killing me!
edit: board and transformers ordered!
Sounds like the 6 ohm tap is a go. In all likelihood, I'll be building/buying new speakers in the future and 8 ohm seems to be the most common impedance. I'll be looking for sensitivity when future shopping/building anyways, so I'm not too concerned about reduced output with the higher load.
Found my Fostex speakers and they're Tekton 4.1's. 8 ohms and 90db, so they'll get a fair shake with the new amp along with the 4 ohm speakers. We'll see who comes out on top. The suspense is killing me!
edit: board and transformers ordered!
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Any opinions on this choke?
Choke for power Supply 200ma 4h
200 mA, 4H, DCR 43 ohms. Is that DCR just going to give me a slightly higher B+? With a 350-0-350 transformer (on the lower end of the spec range), will that be a problem? I'm looking for a choke that will fit inside the enclosure, so options are limited (2 inch height restriction).
Also, how about this for an auxiliary cap:
Obbligato Film Oil 30uF 630V
30uF 630V film oil Obbligato? Pricey, yes, but it will be mounted on the top panel so I want it to look the part!
Almost done ordering the bits and pieces. I'm down to just the non-board parts, with the exception of coupling caps (any opinions on Obbligato? trying to keep shipping down).
Choke for power Supply 200ma 4h
200 mA, 4H, DCR 43 ohms. Is that DCR just going to give me a slightly higher B+? With a 350-0-350 transformer (on the lower end of the spec range), will that be a problem? I'm looking for a choke that will fit inside the enclosure, so options are limited (2 inch height restriction).
Also, how about this for an auxiliary cap:
Obbligato Film Oil 30uF 630V
30uF 630V film oil Obbligato? Pricey, yes, but it will be mounted on the top panel so I want it to look the part!
Almost done ordering the bits and pieces. I'm down to just the non-board parts, with the exception of coupling caps (any opinions on Obbligato? trying to keep shipping down).
Your choice of choke should work if it actually meets the published specs. I think Obbligato caps are intended (or marketed) for audio applications so motor applications may not be mentioned.
I have been using these ASC motor run caps......Sometimes they can be found on Ebay for about half the Angela price. I have a 100 uF 370 VAC ASC cap in my SSE's that have the same sticker as these. I got them on Ebay several years ago for $10 each.
Angela Instruments Online Catalog - Capacitors - Angela/ASC
I have been using these ASC motor run caps......Sometimes they can be found on Ebay for about half the Angela price. I have a 100 uF 370 VAC ASC cap in my SSE's that have the same sticker as these. I got them on Ebay several years ago for $10 each.
Angela Instruments Online Catalog - Capacitors - Angela/ASC
Thanks, George.
As I'm putting together the rest of these orders, space on the top plate is becoming a big issue. I don't think I'll find a cap that will fit inside the enclosure, so I may end up with the choke inside the enclosure. A 2" clearance just barely disqualifies all the Triad/Hammond chokes I've seen that are near the design specs.
edit: how about the Hammond 157Q? 150mA, 3.5H, 98ohms
As I'm putting together the rest of these orders, space on the top plate is becoming a big issue. I don't think I'll find a cap that will fit inside the enclosure, so I may end up with the choke inside the enclosure. A 2" clearance just barely disqualifies all the Triad/Hammond chokes I've seen that are near the design specs.
edit: how about the Hammond 157Q? 150mA, 3.5H, 98ohms
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Each half of the 12AT7 eats nearly 10 mA and your output tubes will be set to somewhere between 60 and 100 mA. Thas can mean 140 to 220 mA through the choke. The 150 mA choke is probably too small. When too much current flows through a choke, it saturates, causing its inductance to drop to near zero becoming a resistor. I used the tiny Triad C-24X because it is rated for 240 mA. It is only 1 Hy but kills hum far better than a resistor. They are 1.5 inches tall so they fit under the deck. You can use two in series if you have the room.
My first TSE amp is the Lexan unit seen on my web site. it works great with all my relatively ineficient speakers, but one day I took it to visit some $10,000 106 db Lowther based horns. Hummmmmmm. So it came home unhappy.
I found a 30 uF 400 volt ASC film cap which I could stuff up under one of the OPT's inside the box where it wasn't too visible. On its second visit, it wasn't afraid of all those big named amps surrounding it. Look at some of the big film caps from Solen. They have some reasonable prices.
You can see the white cap between the holes for the output tubes. An early SSE plays in the foreground. The listeners agreed that the TSE was excellent, but the SSE was "lacking".
Even I could tell that it just didn't sound right. The theory, which did prove to be true, was that it is possible for an OPT to be too big. When the average listening level was tens of milliwatts, too much detail is lost in those big Hammond cores. They sounded good on my 87db speakers because they were running at near full power.
At a later date We tested a box full of OPT's and found that something in the 2 to 4 pound range was optimum for speakers like those. I think the little $28 XSE was excellent at that level. The Hammonds are still in the boxes on the shelf 6 years later. The big Edcors however worked much better, and they are almost as big. They are now in a 307A based TSE.
I usually make an amp on a board like the SSE. That way I can play with it for a while, tweak it, and change things like transformers without destroying a chassis. If I haven't lost interest in a year or so I make a good chassis. The wood SSE became the aluminum SSE in the last picture whch was made in 2007 it still lives on behind my TV set, but got relieved of about a pound of dust a few days ago. There is a wood based version of Pete's big red board (my 125 WPC version) waiting for a proper chassis, and a new creation being born right now that already has a shiney Landfall Systems chassis. I must say that it's harder to make an amp to fit a box, than it is to make a box to fit an amp.
My first TSE amp is the Lexan unit seen on my web site. it works great with all my relatively ineficient speakers, but one day I took it to visit some $10,000 106 db Lowther based horns. Hummmmmmm. So it came home unhappy.
I found a 30 uF 400 volt ASC film cap which I could stuff up under one of the OPT's inside the box where it wasn't too visible. On its second visit, it wasn't afraid of all those big named amps surrounding it. Look at some of the big film caps from Solen. They have some reasonable prices.
You can see the white cap between the holes for the output tubes. An early SSE plays in the foreground. The listeners agreed that the TSE was excellent, but the SSE was "lacking".
Even I could tell that it just didn't sound right. The theory, which did prove to be true, was that it is possible for an OPT to be too big. When the average listening level was tens of milliwatts, too much detail is lost in those big Hammond cores. They sounded good on my 87db speakers because they were running at near full power.
At a later date We tested a box full of OPT's and found that something in the 2 to 4 pound range was optimum for speakers like those. I think the little $28 XSE was excellent at that level. The Hammonds are still in the boxes on the shelf 6 years later. The big Edcors however worked much better, and they are almost as big. They are now in a 307A based TSE.
I usually make an amp on a board like the SSE. That way I can play with it for a while, tweak it, and change things like transformers without destroying a chassis. If I haven't lost interest in a year or so I make a good chassis. The wood SSE became the aluminum SSE in the last picture whch was made in 2007 it still lives on behind my TV set, but got relieved of about a pound of dust a few days ago. There is a wood based version of Pete's big red board (my 125 WPC version) waiting for a proper chassis, and a new creation being born right now that already has a shiney Landfall Systems chassis. I must say that it's harder to make an amp to fit a box, than it is to make a box to fit an amp.
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That's exactly what I needed to hear. I knew you were using a 1H choke, but everyone seems to be using these 5-10H behemoths. There just isn't going to be room for that in my build. I may be able to squeeze in two Triads, but Edcor also makes a 2H 200mA choke that's just a hair under 2" tall. Should work with persuading.
I'm still undecided on that 4H 200mA choke I linked to earlier. It seems too good to be true and it's a no name brand. Better the devil I know than the devil I don't?
I'm still undecided on that 4H 200mA choke I linked to earlier. It seems too good to be true and it's a no name brand. Better the devil I know than the devil I don't?
I can't even begin to imagine trying to pick an OT for a headphone amp, mostly because I've got several sets of cans that I like to use depending on mood/genre. Grados are 32 Ohm and Senns are 600+. I suppose the impedance plays less of a role when the current is so small? I've got a Starving Student Millet Hybrid (point to point) for quiet time listening.
Asked Edcor to add their 2H, 200mA open frame choke to my order. It should fit in the chassis as it's 1.9" high and 1.75" wide (I'll mount it sideways if needed). I'm seeing those ASC caps at several online shops, so hopefully I'll find a single source for all my panel parts (Parts Connexion is looking promising).
Do I need to be careful with the rating of the DPDT switches for UL mode and CFB?
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