Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Eros Tape => Topic started by: Mrbryanmarshall on March 30, 2019, 10:37:21 PM
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I've never written a review article but felt compelled to after assembling and of course, listening to the Eros Tape Stage kit.
Building:
The last time I built any type of electronics kit was when I was about 13, well over 20 years ago. Since then, I've only rewired my electric guitar a couple of time when changing pickups and pots etc. Needless to say, my experience can be measured in hours rather than months or years. I only have basic electronic knowledge and would have no idea how to trouble shoot any serious issues or repair any thing.
Despite all of this, I managed to put together a fairly complicated piece of kit and only hit maybe half a dozen speed bumps - more on this later.
I upgraded my soldering iron to a fine tipped version which cost about $12 and dug out the side cutters and needle nose pliers - both of which are essential. I bought a wire stripper but never used it as the teflon wires are way to slippery for it to grasp. So, ended up using a Olfa cutter/craft knife to carefully strip the teflon and the 3 core wires.
My multimeter is also an $15 Ace Hardware version. With this basic kit, I was surprised at the quality of the results. So, you don't need much to get this up and running.
The instructions are super clear in my opinion. Two of the (maybe) six issues I faced were simply because I missed an instruction, maybe because I didn't take enough breaks. Fresh eyes are very important in putting a kit like this together.
Not being very electronics savvy, I also got stuck with some of the resistance values. Namely the 130K values should actually be 200k. In retrospect, this is obvious as you're using 200k resisters at the relevant terminals.
The other issues were mostly resolved by re-soldering, tidying up joints or putting a wire in the wrong solder pad. E.g.: On the voltage check for the regulator, one wire had sheered internally so it was visually fine, but was only found when it popped out on a re-solder, right at where the bare wire met the insulation.
The final issue was the T11 to T12 (Not T10) 200k resistor terminal connection, which is incorrect in the manual. This is in the forums so definitely read all of these before starting! I actually destroyed the resistor when trying to correct, so had to order another one and wait several days for a replacement - tricky in Dubai! Once this was in place, all resistance and voltage checks fell into place.
I am also getting about 76v (instead of 100v) on OB terminals on each board. But, it works and have a feeling that this may be because I am on 240v, not 110v - would appreciate some input here!
Also in the build, I stained the box Walnut, painted the face plate matt black and the transformer bell red. I made sure the bell was covered in masking tape to make sure it didn't scratch with the large amount of moving around that is required. I didn't do this for the edges of the face plate which wore through. But, this is fine because it isn't noticeable when mounted in its final position.
I also ran out of red wire, so just used the black for the Eq switch. No problemo.
How does it sound?
I read a comment in these forums about testing with your ears, not with readings. I am an advocate of this and can initially confirm that it sounds fantastic after only a couple of hours of listening.
I have a JCorder Technics RS1500 two track and got this to use because I have a Flux Magnetics Direct out head installed. My amp is a Line Magnetic 518ia with tubes upgraded (845s, 12ax7s, 5AR4, 6L6Gs) and speakers are the new Klipsch Forte iii's.
I have some fresh copies of old IEC classical production masters. Some from 4 or more track 1" or 2" and some from 1/4".
These of course sound great. Once past the potential quality issues of the original recordings, the first impression was that the sound stage is wiiiiiiide... I spent a while tweaking the toe in of these speakers when I got them for my record setup and was happy with them. However - and I don't know why - but I found that I could "toe -out" the speakers even more and this had a great effect at having an even wider stage.
On an OK recording (IEC) of Saint-Saens Symphony No.3, (the organ one,) some parts of the performance felt like they were being beamed from a different dimension right into the audio cortex of my brain. Goosebumps? Forget about it. This was a different experience all together.
On a rather bad recording of Rachmaninoff Piano Concerto No.2, (also IEC,) I still got the impression that this combo of Eros and FM head got way more out of the tape than was to be expected. Even a bad recording sounded full and dynamic, full of force.
My only potentially negative observation is the lack of bass oomph so far. I think this is down to the recordings and type of music/performance rather than the Eros. I will update this in time once I've listened more. There was much fuller bass from a Carmina Burana IEC tape, (which also lead to Goosebumps btw,) but again, this isn't really bassy music...O Futuna (the main theme you will know) was full and lovely and more than happy with this as is!
Another observation is that it needs a little time to warm up. This is by no means a negative and typical of tube gear. 10 - 15mins warm up results in a better sound and is about the same as my Decware ZP3 phono stage and main amp too.
I have my wifi router near my hifi. I have to turn this off when listening to music - records or tape - as these phono and tape stages do pick up the noise. I read a bunch of forums about tube rush and hiss - mine is completely removed when the wifi is off. Which is also nice actually to turn that off when listening to music!
That's it! a great kit to put together but more importantly, it sounds great. I can't wait to get out of the office to get in some more listening and will post a couple of up dates as and when.
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Nicely done, thank you!
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I am also getting about 76v (instead of 100v) on OB terminals on each board. But, it works and have a feeling that this may be because I am on 240v, not 110v - would appreciate some input here!
What do you get at KregB and OA on each of those boards? This voltage will not change based on your wall voltage.
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Bryan? I haven't seen too many flat finishes, looks great with the red accent. great work.
Karl
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What do you get at KregB and OA on each of those boards? This voltage will not change based on your wall voltage.
I will have to check my notes. But remember one was spot on and was was a bit off, but in spec. Will check later.
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Also re. Bass, I played a Bill Evans radio broadcast tape, the double bass is full and great. Not that the internal technics electronics can be accused of being boomy, but the Eros is cleaner and tighter I guess, with a bit more texture.
No probs at all, just recording related on the previous classical stuff.
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What do you get at KregB and OA on each of those boards? This voltage will not change based on your wall voltage.
Here are all the voltages i just re-took them now:
A Side: (actual | target)
Kreg 1 | 1
breg 99 | 100
OA 157 | 170
IA 222 | 225
BA 0 | 0
OB 98 |100
B Side: (Actual | target)
Kreg 0.8 | 1
breg 76 | 100
OA 194 | 170
IA 229 | 225
BA 0 | 0
OB 70 | 100
So, all over the show... :(
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Can you swap the EF86 tubes and recheck the voltages?
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New numbers with swapped Tubes:
A Side: (actual | target)
Kreg 0.8 | 1
breg 76.3 | 100
OA 196.8 | 170
IA 223 | 225
BA 0 | 0
OB 70.8 |100
B Side: (Actual | target)
Kreg 1.4 | 1
breg 98.9 | 100
OA 156.4 | 170
IA 225 | 225
BA 0 | 0
OB 97.1 | 100
so, tube issue?
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Ah, that's good to know. In circuits with DC feedback (especially ones I didn't design!), it can sometimes be difficult to separate variations in tube performance from an actual assembly error.
I would bet that if you left your Eros on for a few days, these voltages will settle down a bit.
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thanks! So, just a wear in issue basically?
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Yes, this is very likely.
PJ, of course, may look at the set of voltages and have a different idea.
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So, these voltages are OK? I've order some new tubes anyway just to play around, will see if that makes any difference
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Have you left your Eros running for a few days, then rechecked them?
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I've been leaving it on whilst i've been home. So, not that long in total, doing this for a while longer and going to see if there is any shift this weekend.
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I left this on for a total of about 40hrs over a week or so. The voltages stayed basically the same as before, no real shift.
I replace the 2x EF86 with NOS RFTs and the ECC88 with a NOS Sylvania. Here are the new readings with those tubes. These were taken after about 5hrs of leaving the EROS on:
A Side: (actual | target)
Kreg 1.1 | 1
breg 97.5 | 100
OA 159 | 170
IA 222 | 225
BA 0 | 0
OB 95.3 |100
B Side: (Actual | target)
Kreg 1.42 | 1
breg 98 | 100
OA 156.9 | 170
IA 223 | 225
BA 0 | 0
OB 95.8 | 100
These look a lot better, with the only outlier being the Kreg on the B Side, which i am not worried about.
Regarding sound. These tubes are fresh, but are noticeably quieter. With the stock tubes, the background noise floor seemed to worsen and became very obvious after a few days. It wan't bad, but quite noticeable on quiet sections of music - may because of very sensitive speakers?
Anyway, very happy with this and will update if/when.