Bottlehead Forum
Bottlehead Kits => S.E.X. Kit => Topic started by: physicsmajor on October 21, 2016, 07:40:33 PM
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So will the new kit be S.E.X. version 2.2, or turning over a new number to 3.0? Exciting! This was a really awesome kit, I'm glad it'll be back in the stable - not least so I can recommend it.
I wondered if you'd just move to the 6FJ7 compactron version with minimal wiring changes, though the layout and allusions to a 'surprise tube' in the email makes it seem like more may be afoot.
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Doc, is there a timeframe for when more details will be released?
I was about to the pull the trigger on a SEX around the time that it was announced it would be discontinued and I still have an itchy trigger finger.
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We will have more info available soon. It's the 99% the same circuit as the previous version, with a different tube and a better layout that makes the build easier. There is a small change in the heater supply that brings the noise floor down from that of the previous version.
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Cool, I can't wait to see what you come up with. I love my S.E.X. Amps. I'm curios to hear how the sound of the new tube compares with the 6DN7.
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If it's 99% the same then it should be easy enough to convert the 2.1 to the new tube if you wanted to. That's what the SEX is all about right? I'm curious about the tube too. The old page specified that it was easy to mod it to use 6EM7/6EA7 tubes.
My modded SEX is my go to amp at the moment. It's a wonderful amp and I'm excited for the latest update!
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If I may be so bold enough as to guess, I'm thinking the 99% same circuit means that now we will see a pair of additional 100 ohm resistors in the heater supply. I already did that on my SEX, and I found it a worthwhile improvement to the point I was curious why it not had already been implemented.
Next I'm thinking the tube change is likely related to ease of availability - 6DN7's aren't a "dime a dozen" any more
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Anyone who comes to the DIY meet today will be able see for themselves what tube we plan to use. We'll have the prototype that was built for the manual available to inspect.
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Recap post by Doc B. says it is the 6FJ7, but also notes it's got a significantly lower noise floor than the current S.E.X.
I'm curious about the changes to the circuit (or perhaps just the layout?) to achieve this.
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After I finished building the second 6FJ7 SEX amp, and verified that the chassis plate layout would work as intended, I spent a lot of time trying different configurations of heater grounding and measuring the noise level with each of them.
The layout had to change to accommodate different heater rectifier diodes, along with the new universal power transformer. There is now much more room for larger parallel feed capacitors as well, as those buggers get pretty huge.
-PB
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That is great to hear as i always found mine a fantastic pairing with sensitive cans like Grados, but could never recommend one as the stock kit wasn't quiet enough. Glad to see the kit coming back :)
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After I finished building the second 6FJ7 SEX amp, and verified that the chassis plate layout would work as intended, I spent a lot of time trying different configurations of heater grounding and measuring the noise level with each of them.
The layout had to change to accommodate different heater rectifier diodes, along with the new universal power transformer. There is now much more room for larger parallel feed capacitors as well, as those buggers get pretty huge.
-PB
Neat I'm looking forward to seeing the new lay out in the flesh. Can I ask if the uf values and voltage ratings for the parallel feed and interstage capacitors are similar to those used in the Sex?
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Yes, of course. The 6FJ7 is a 6DN7 structure in a different envelope. So the circuit is going to be the same. To reiterate - different tube pinout, universal transformer, better layout and manual, slightly different heater connection and quieter operation because of it.
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Could the new heater circuit and parts be retrofitted into the 2.1?
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I know it will be quieter which is a great thing.
Does the sound quality change much from the prior version?
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It sounds essentially the same except that it is more quiet and hence has little better resolution.
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Is there a need for a C4S Upgrade Kit for the SEX 3.0?
On the fence to either pre-order or wait to see what's in store for black friday/cyber monday.
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The C4S will be released sometime next year.
Orders for this kit are coming in. At the close of the preorder period, parts will be ordered to the quantities required. If you choose wait longer to place your order, you will not be in the first batch, and therefore will have to wait longer for shipping.
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Is the much choice of different tubes and will tube rolling see significant improvement?
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Is the much choice of different tubes and will tube rolling see significant improvement?
There are a fair number of variants in the 6FJ7, with a mix of gray and black plates. Luckily, however, I haven't run into any series heater configurations, so that will be completely consistent.
IMO, tube rolling was never a particularly important consideration in the 6DN7 kit.
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There are a fair number of variants in the 6FJ7, with a mix of gray and black plates. Luckily, however, I haven't run into any series heater configurations, so that will be completely consistent.
IMO, tube rolling was never a particularly important consideration in the 6DN7 kit.
Thanx heaps for the info
I am looking forward to the assembly of my kit when it becomes available
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I'm in. You have my pre-order and I threw in a Stereomour II shunt regulator upgrade for good measure. :)
When people come over to my house and they hear the S.E.X. amp they want one (and a set of Orca's). I've purchased two S.E.X. amps directly from Bottlehead and two used, unassembled kits from private parties in the past. I only have one left. Thats gotta tell you something. Keep up the good work, Bottlehead! You guys rock.
Tom AKA "Natural Sound" in Albuquerque.
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Thanks Tom, and thanks to everyone who has preordered!
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Given the similarity of the circuit to the 2.1 version, will the output (parafeed) capacitor for the 3.0 also be rated as a 1.5 uF?
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Given the similarity of the circuit to the 2.1 version, will the output (parafeed) capacitor for the 3.0 also be rated as a 1.5 uF?
Yes.
The calculated nominal is 1.25uF so 1.0uF is as good as 1.5uF. You could experiment, going as low as 0.625uF, or as high as 2.5uF. The smaller values will give better deep-bass power with less extension, but there is substantial interaction with the speaker and the listening room.
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Yes.
The calculated nominal is 1.25uF so 1.0uF is as good as 1.5uF. You could experiment, going as low as 0.625uF, or as high as 2.5uF. The smaller values will give better deep-bass power with less extension, but there is substantial interaction with the speaker and the listening room.
PJ, I've seen you discuss this before. Does that mean the bass will have more oomph but not go as low with the smaller values (taking the speaker/room variables out of the equation)?
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That would be a reasonable paraphrase of my post. But you can't really take the speaker/room out of consideration; the possible interactions are too complex to trust analyses. Listen and learn.
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Just placed my order. 8)
Now I just need to look into some affordable speakers to go with it. Wish I could afford orcas.
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For speakers you can look at the Madisound Fostex kits. They look interesting and reasonably priced.
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FYI - I have used 1.0uF with wonderful success, and it seems that a greater selection of capacitors with sufficient voltage rating is available in this capacitance value.
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Thanks, P.B.
I used some Mundorf 1.5 uf in my S.E.S. 2.1 because that is what came with the kit.
I'll try using the same caps in 1.0uf in my 3.0 when it arrives, probably in January.
Also, I plan to install the C4S for the S.E.X. 3.0 when it is available. For those of us that will be assemblying the kit before the availability of the C4S, can we be told where it will be mounted, the individual components that will be removed (if any), etc.? This informtion can help us during the initial assembly to be prepared for the C4S upgrade.
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I would strongly recommend installing the C4S before changing out the 0.1uF interstage coupling caps.
-PB
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I would strongly recommend installing the C4S before changing out the 0.1uF interstage coupling caps.
-PB
I'm a little bit confused. Can you expand on that a little please?
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I would strongly recommend installing the C4S before changing out the 0.1uF interstage coupling caps.
-PB
I do not currently have plans to touch the interstage 0.1 uf cap only the 1.5uf parafeed output cap. So, I'm assuming changing the parafeed cap before the installation of the C4S when it becomes available is OK (I'm thinking positioning/location, considering I don't choose some gigantic size cap!).
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Quick question about the new SEX, and BH amps in general...is it OK to operate the amp long term with the chassis plate in a vertical position?
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Yes to the SEX kit. Indirectly heated tubes can be oriented on their side.
Maybe to the DHT amps. It depends upon how the tube filament is oriented. It needs to be vertical. If it is horizontal there is a slight possibility of it sagging and hitting the grid.
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Thanks Doc!
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(asking about recommending install of C4s before changing out caps)
I'm a little bit confused. Can you expand on that a little please?
The reason is that the C4s provides a material upgrade to the sound, so you should strongly consider applying the upgrade(s) to the stock kit, hearing the differences, and then if you still want to tweak go after the caps/resistors.
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While there is plenty of room in the new kit for cap upgrades, the C4S kit will occupy a little bit of space that you might be tempted to use for larger interstage coupling caps.
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While there is plenty of room in the new kit for cap upgrades, the C4S kit will occupy a little bit of space that you might be tempted to use for larger interstage coupling caps.
Ah, OK, that makes more sense. Thanks.
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I'm in. You have my pre-order and I threw in a Stereomour II shunt regulator upgrade for good measure. :)
When people come over to my house and they hear the S.E.X. amp they want one (and a set of Orca's). I've purchased two S.E.X. amps directly from Bottlehead and two used, unassembled kits from private parties in the past. I only have one left. Thats gotta tell you something. Keep up the good work, Bottlehead! You guys rock.
Tom AKA "Natural Sound" in Albuquerque.
Just got UPS tracking info. ;D
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Just received my S.E.X. 3.0 via UPS!
I already have a 2.1 version w/C4S in the living room listening area and wanted another S.E.X. on my desk.
The kit came with two different brands of 6FJ7: GE and Sylvania
I am currently sourcing additional 6FJ7s and what to have pairs of the same maunfacturer.
I would not be surprised to hear that GE, RCA, and perhaps Sylvania 6FJ7s are all made by the same manufacturer (probably GE).
I really don't expect any substantial sonic differences but I would like to have tubes with the same markings (if not only for appearance).
I remember reading in this forum that a given manufacturer of the 6DN7 tubes for the earlier S.E.X. versions should not be mixed with another manufacturer.
Can this be said for the 6FJ7 as well?
Just curious.
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I don't know who said not to mix 6DN7s, but that's rubbish. They all run the same in the old amp and it won't hurt anything except a case of OCD. Ditto 6FJ7s.
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Doc B
This is where I got the idea of not mixing brands of 6DN7s:
http://bottlehead.com/smf/index.php?topic=6795.msg82645#msg82645
I used different brands of 6DN7s before.
Anyway, I may struggle against my OCD concerning matching brands!
How it sounds is what really matters.
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Tubes are matched by manufacturer and structure. Branding is separate from manufacturer. Both tubes were made by GE. Look for the permanent dots that GE etched on the glass on all tubes they made. Also I will bet that the plate structures are the same (grey, black, or one grey one black), because your tubes were hand matched, by me.
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Thanks, Josh ... learning everyday!
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I got my kit in this week and finally got around to taking a spin around the manual. Here are my observations of the improvements over previous generations that I have built.
PT10 Power Transformer. Multiple primary taps allow you to fine tune to your specific mains voltage. (115V and less, 115V to 130V) (210V to 225V, 225V to 235V, 235V to 245V)
New style heater rectifiers that mount to the top plate. This greatly simplifies assembly. The 1N5820's in the older kits were a bear to deal with sometimes. There is another nifty little trick used in the heater circuit too. No, I wont give any details. You have to buy one yourself to find out. ;)
Use of a better quality interstage cap along with a better solution for attachment.
Better layout providing more room for Parafeed caps.
CAT5 wiring for input and output wiring. I've used this type of wiring before with nice results.
All in all some very nice tweaks. There may be a few I missed too. Good job guys. I cant wait to build this.
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In the middle of building one for a friend, all the changes get a thumbs up from me too. Transformer taps are a nice touch, wired for 240v all the secondary voltage are spot on which they never were with my 2.1 as the mains here is 235-245v depending on the time of day. Heater circuit diodes are interesting, looking at the specs they have much lower reverse leakage so it will be interesting to scope the supply vs my 2.1 as i recall it had rather large spikes. Also nice to see the PVC wiring has been replaced with the teflon coated wire, same for the cat5 in the audio path. Interstage cap is a nice change too, as is the revised layout and grounding scheme. Downsides, to me its not as pretty looking as the 2.1, but its a small price to pay for a quieter amplifier. Nice upgrade overall, looking forward to getting it up and running...
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Working through the build of the 3.0 and this is the simpliest of the six BH kits I have done!
I have stopped at the heater circuit connection to the "B" side, however.
The scematic on page 6 shows that both the heater connections for "A" & "B" are the same; e.g., "A" A1 is connected to "B" B1 and "A" A12 is connected to "B" B12.
However, the directions on page 39 direct me to connect "A" A1 (Black lead) to "B" B12?!, and then "A" A12 (Red lead) is then connected to "B" B1?!
The picture matches the directions on page 39.
There is inconsistency between the scematic and the directions on page 39.
{I know most people don't follow the scematic, but it is very specific.}
Cna you explain why the tube socket heater connections are "swapped"?
I'm continuing with the build per the directions and picture.
Also, on page 54 the terminology used describing the speaker binding posts seems wrong.
The directions identify these as left and right "inputs". These are really one of the outputs to the circuit (the other being the Headphone Jack).
Thanks
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Interesting catch, the schematic numbering is incorrect so follow the directions/photos. Reason being is the resistor from pin 12 to ground needs to connect to a red wire on the A side, and a black wire on the B side.
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Thanks for the quick response.
Go PATS!!!!
edited
Here's the corrected schematic for the heater circuit:
Edited by J. Harris: please do not post schematics without permission.
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Thank you for pointing these out. I will get these corrections into the manual.
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Thank you for pointing these out. I will get these corrections into the manual.
I apologize for posting the change to the schematic - I kinow better!
I just wasn't thinking this morning.
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Just finished the resistance and voltage checks and currently listening to the S.E.X. 3.0 at my desktop.
I wired the outputs for 4 ohms. I'm currently listneing to the amp via my laptop, Radio Tunes, through a Schiit Modi 2 DAC, feeding Klipsch R14M desktop 8 ohm speakers. I wired this amp for 4 ohms with the intent to purchase a pair of Decware 4 ohm desktops.
This amp sounds simply fantastic with the current setup, however.
Prior to this I have been using a LM3875 Gain Clone amp at the desktop and the 3.0 has noticibly clearer and extended upper and lower registers. The amp is very quiet. I have listened with NAD VISO HP50 headphones and it is still very, very quiet.
Wow, this amp sounds great and I haven't even put it through any break-in. I'm using a pair of GE Black Plate 6FJ7s.
I installed a pair of Mundorf parafeed caps and a Gold Point V47 stepped attenuator. The Gold Point attentuator fits but I had to chisel out some space in the base to accomodate it because it came too close to the edge of the plate.
I installed a power-on indicator lamp (117VAC LED) I had used in my Gain Clone to good effect, but it didn't work with the 3.0 circuit topology. With the lamp installed the circuit would not develop enough DC voltage for the heater circuit. So, I am left with a hole in the plate just above the power switch.
Here are some pictures:
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Seems strange that a power indicator LED on the mains side of the power transformer would pull the mains voltage down enough to affect the secondaries.
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I haven't put my head into it yet, but I am confused about the LED, too. I only got 0.1 VDC on the heaters.
I have a couple more of them and I'm thinking of trying it again (maybe I had a bad light).
If I do I will want to replace the power switch because I have already soldered and heated it three times.
I guess I want to have one on the side just in case.
Anyway, thanks for the great amp. A wonderfully easy build (maybe the 680 ohm resistors terminals could have been a little closer together) and absolutlely beautiful performance.
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I see you went with the brushed metal finish on the plate chokes, very nice 8)
I have seen some LED's fail and create a short, usually when the reverse voltage is exceeded.
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The LED https://www.zoro.com/value-brand-round-indicator-light-green-120vac-24m050/i/G4705181/ (https://www.zoro.com/value-brand-round-indicator-light-green-120vac-24m050/i/G4705181/) is simply connected in series with the switch - the same as in the solid state amp.
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Sounds odd to me, i would have expected it to go across live and neutral. If it is in series it would need another diode in parallel or it would block half the mains cycle. Really need a datasheet to know what exactly is inside that unit, does it have a reversed diode in parallel, or just a current limiting resistor?
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The link has enough of the specs to determine it should be in parallel with the power transformer primary - not in series.
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You are absolutely right. It should be connected in parallel.
Here's my story:
When I installed this light in the Gain Clone amp I tried the series connection and it didn't work.
I installed it in parallel and it worked as designed.
Over a year later .... I forgot about my lessons learned and tried to do it in series. The light bulb (in my aged skull) did not come on until earlier today.
Moral of this story: I didn't learn from my previous mistake...and...getting old is a bitch and not for sissies!
So, I put pen to paper and designed what I think is the circuit for this lamp.
I would chose a capacitor to provide the correct amount of capacitive reactance to drop a very large majority of the voltage to bring down the current to the lamp designed 4.4mA. I would put in a resistor to handle any current spikes.
I wired the lamp directly across the primary of the main transformer.
Here is the schematic I made (nothing about this circuit should be of a proprietary nature):
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Thank you for pointing these out. I will get these corrections into the manual.
Another correction you may consider for the S.E.X. 3.0 manual:
On page 59 (Resistance Check), Terminals 28 & 29 should read "infinity".
These terminals have nothing connected to them and they are mounted to the chassis plate with insulating fiber washers and a plastic acorn nut.