Bottlehead Forum
Bottlehead Kits => S.E.X. Kit => Topic started by: albertoderoma on May 01, 2013, 07:14:24 AM
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Hi there,
I've been enjoying my SEX tremendously since I first built it in 2007. It makes harsh digital sound sweet.
A couple of weeks ago, I finally got around to assembling the Seduction pre (2007 edition! Yes, it sat in my garage for 5 years.)
Assembly went without a hitch and all ohm and voltage checks were within range. Connected my vintage Empire 280 turntable to it with a Shure M97xe cartridge at the input and my SEX at the output and it worked right off he bat. So far so good.
Here's the problem, the sound is fatiguing. I can't pinpoint anything particularly harsh. I can't quite put my finger on what makes it fatiguing, perhaps a forward midrange ... or perhaps the sound is too compressed or distorted.
I know it's not my turntable/cartridge + speakers combo since they sound great with other phono stage. And it can't be the SEX since it's my go-to amp whenever I need to play something that is poorly recorded and fatiguing ... or could it be the SEX -- that I need a proper preamp to deal with the relatively low signal.
I am hoping that it's just a matter of giving it enough break-in time, but if that's the case it would be the most amazing example of break-in in my 20+ years of audio experience.
Any suggestions would be greatly appreciated. Is it just a matter of a loooooong break-in ... or punishment for having waited 5 years to build it :-).
Thanks,
Alberto
PS Big kudos for Doc + team for putting together instructions such that I was able to get it right the first time ... as I did with the SEX.
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It will take at least 50 hours for the capacitors to settle down. That's with music playing, not just turned on. Compressed, forward, and fatiguing are all things that I hear from new caps.
I find that a good SET system will often make break-in more obvious. But I have done the experiment of break-in without listening (to eliminate the effect of "getting used to it") and it's real. Still bugs the engineer in me to not know why, but that same engineer finds it hard to argue with reality!
If the problem remains, we can try some diagnostics and brainstorming.
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Thank you for your reply Paul. Will do more break-in and report back in a couple of weeks or so.
Since I find it rather grinding to listen to as it is, I will simulate the break-in experiment you have done (i.e. run a signal through, but without listening - at least not at regular listening volume and see if things improve. If that happens, I will be even more convinced that this break-in thing is for real ... and not at all subtle in some cases.
Thank you again for taking the time to reply Paul!
Alberto
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Alberto, I have the SEX and Seduction combo and the sound is nice and warm. I'd definitely try rolling the tubes a bit if you're still having a problem after the caps have gone through their break in period.
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Yep, I have the same combo. No fatigue here. Let the caps break in and maybe try some other tubes.
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I see that tubes4hifi.com makes a reverse RIAA filter kit for $39... you could plug in your laptop or a cd player, put it on repeat for a couple of days, and not have to worry about flipping records during burn-in.
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Plug your laptop into it on nearly the lowest setting and play music through it. You don't need a reverse RIAA as your not listening to the music. I will start at zero volume and increase it until it's a little below listening level, then, turn off the power amp and let it play for 100 or so hours.
Caps need signal to break in. Tubes do not (most of the time) EML specifies something different, for all other tubes I know of they need time with or without signal to break in).
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The Seduction was around for so long that there have been different tubes and capacitors supplied over the years. What tubes did you get, and can you post a pic of the underside so we can see the caps? Could simply be caps needing break in like the guys are saying, but some 6922/6DJ8s can be bright in the 8kHz region.
Another possibility is that there is something out of spec in the RIAA that is making the frequency response a little off. You might want to double check the cap values and which terminals the caps are attached to.
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Thank you for all the advice guys.
Doc, the tubes are indeed Sovtek 6922. Do you have suggestions for a good (and affordable) replacement that might address the problem ... in case the break-in is not sufficient. I listen to music all day while I work so being non-fatiguing (erring on the side of warm and forgiving) is important to me, that's why I enjoy my S.E.X. so much. A tube with those characteristics would be ideal.
Thanks again for a great product and the super support.
Alberto
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A good source of 6922/6DJ8 tubes would be http://www.tubeaudiostore.com/index.html (http://www.tubeaudiostore.com/index.html)
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First of all, sorry for posting this mostly Seduction question on the S.E.X. board, I did not see the well hidden Seduction legacy forum. Feel free to change it to the correct board if this is a problem.
Per Doc's request, I've attached a photo - no snickering at my soldering skills pleeeze :-[.
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi1288.photobucket.com%2Falbums%2Fb493%2FAlbertoAficionado%2FSeductionPhonoAmplifierBottom_zps6a0ab11d.jpg&hash=bddb38ead0f52cdf73e774a8ad0e3c4b220c0b4b)
Two questions:
1) There were supposed to be 2 .01MF 1.6kV capacitors for the RRSF and full-wave rectifier part of the circuit. In my kit, I had one 0.01MF and one 0.015MF (both 1.5kV). I assumed that since these were outside the signal path, the difference in MF would not be an issue so I went ahead and used the 0.015MF anyway. Was I wrong?
2) Since experiencing the problem with the edgy/forward sound, I've done some research on the Sovtek 6922 and, as Doc mentioned, it does have a reputation for being on the harsh side. I was thinking to testing the tube hypothesis as the culprit by buying a pair of JJ E88CC / 6922, which have the reputation of being: "... a great alternative to ECC88, 6922 and 6DJ8's for preamplifiers if you are looking for a warmer, smoother sound at a low price." It definitely fits my budget, or lack thereof ...
Thank you again for the help, and please feel free to repost this to the proper forum.
Thank you,
Alberto
PS I should emphasize that --- other than the very noticeable fatiguing nature of the sound --- there are no hums, strange noises or imbalances or any other indications that there is something wrong with the Seduction. It just sounds forward and edgy.
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OK, those are the Panasonic ECPQ/U caps. The Sed did not have a particular reputation for being edgy, and those caps were what came with it for many years. So I would guess it is indeed the tubes that you are not liking. And the .01 vs. .015 is not a problem in the RRSF.
I am probably not the person to ask, because I was fortunate to get a fairly good sized collection of Amperex 7308s and a few Telefunken E88CCs for my own use years ago. These sound the best to me, but are now stupid expensive.
What we have gone to is the Russian 6N23p, which I think sounds great for the money. But that may be what the Sovtek 6922 is, I don't know. If I have a Sovtek at the shop I will compare it to the Voshkod 6N23Ps.
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I like the sound of the JJs a bit more than the Sovteks, but my pair of Sovteks are noticeably quieter than the JJs, so that is what I settled on because I was doing a lot of headphone listening at the time I actually sat down to compare tubes. The Sovteks aren't offensive to my ears, the JJs just have a bit more je ne sais quoi. I had a pair of Electro Harmonix (that's what shipped with my kit) but they died after several years of heavy use, so no direct comparisons. Also worth noting, the tubes corndog linked to are Sovteks, the extra cost being for testing/matching services. You might want to look elsewhere if it is really the Sovtek sonic signature that's rubbing your ears the wrong way.
Right now the JJs are in the Reduction prototype I have in my room. I'm not really ready to go into the sound of that preamp yet, since it is still breaking in. I will say that after feeding it radio static for ~24 hours, it started sounding a lot better. The best use I have found so far for Seattle radio...
I'd still recommend burning in your caps: it's free and easy and tube rolling remains an option down the line. While the Panasonics might not need as much as some other types, it won't hurt anything and it gives you a better baseline for comparisons. Have you tried listening again at all (with or without doing something for the particular purpose of burn-in in the interim)?
Edited to add: IMHO,YMMV, don't buy JJs just because I said so, et cetera, ad infinitum.
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Thank you Doc and Joshua. I'll do one more week of break-in, by then it will have been well past 50hrs.
>Have you tried listening again at all (with or without doing something for the particular purpose of burn-in in the interim)?
I've been playing it 3-5hrs/day for the past few days. Some times I am listening, others I have the S.E.X. volume at zero, running just for break-in purposes. It's so hard to tell if things are changing, perhaps it's a bit less harsh now, but it still sounds edgy, which I find particularly strange since the S.E.X. adds such deliciousness to most inputs.
I will check back next week after more break-in ... Thank you all for the help and suggestions, I appreciate it very much!
Alberto
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There are a lot of good tubes out there. I'm a fan of the Russians. I have used them in my Seduction for years, cheap mother that I am. Here is a link to a thread I started in the Seduction folder:
http://www.bottlehead.com/smf/index.php/topic,1029.0.html
You will find a list of tube number equivalents there. This will open up your search to tubes you would overlook otherwise.