CECAA850 Posted April 18, 2015 Share Posted April 18, 2015 After picking Eriks brain (thanks!) I decided to take the plunge and order this pre. It's a Transcendant Sounds grounded grid preamp. It will be paired with one of Justins Stereo 15's and my Cornscalas in my "bedroom 3" system. I'm still working on the system as far as a source goes but I've listened enough to give a couple impressions. 3 Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted April 18, 2015 Author Share Posted April 18, 2015 My main criteria was that the pre be absolutely silent. I'm new to tubes and I know they can be a little noisier than SS. This pre definitely met the requirement. Turning it on or off and moving the volume 0 to 100% adds absolutely nothing to the very slight hum from my amp. The case is a little utilitarian but I like the face. 3 Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted April 18, 2015 Author Share Posted April 18, 2015 (edited) The back is plain as well. Labels wouldn't add much to the cost of the assembly and would be nice to have. There's a couple extra holes in the case on the back and several on the bottom. I don't know if this case is used for more than one assembly but it gives the overall impression that this IS a kit . The upper case extends slightly past the rear panel where it should be flush. Again, all you see is the front and back when it's installed and none of the above are visible. It's very nice looking from those angles. The worst problem though was the threaded inserts for the screws. Three of them fell out as I was putting the case on causing me to pull the cover 3 times to reinstall them. They're pressed in but not held in very well. They could use a drop of glue or something to help them stay in place as the plate is too thin for them to really grab. Edited April 18, 2015 by CECAA850 Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted April 18, 2015 Author Share Posted April 18, 2015 OK, the money shot. This pre can be purchased as an un assembled kit or pre-assembled from TS. I purchased the unassembled kit. If anyone here thinks for one moment that I assembled this myself, you're gravely mistaken. This is Maynards craftsmanship. He did a stunning job and I'm extremely thankful I sent it to him. During assembly, he found that one tube had a dead leg and the two others were marginal. I never would have caught that. I contacted TS and was told that Maynard measured some anomaly and that the tubes were fine. I took the "tube fanatics" word for it and ordered 3 more tubes of the same number and manufacturer as what came with the kit. These tested perfectly and then the entire unit now scoped perfectly. I'm really glad I know my limitations and had Maynard build this. 4 Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted April 18, 2015 Author Share Posted April 18, 2015 (edited) I'm not into flowery hyperbole but I will say that this is the best this system has sounded. The preamp just flat gets out of the way. I'm extremely happy with it and thank Erik for recommending it. I can't thank Maynard enough for all his help. Overall, I'd give the kit: A 10 where it counts in sound. A 5 to 6 in build quality and fit. A 9 in finished appearance. A 1 in customer support. Would I recommend this kit? Most definitely. Edited April 18, 2015 by CECAA850 Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted April 18, 2015 Share Posted April 18, 2015 top notch. the other stuff is cool, but Maynard is THE MAN. Quote Link to comment Share on other sites More sharing options...
dubai2000 Posted April 18, 2015 Share Posted April 18, 2015 Congrats - it's a great preamp - currently I am running it in combination with the (discontinued) SEOTL on my Khorns - a very musical combo and quiet indeed! Wolfram Quote Link to comment Share on other sites More sharing options...
twistedcrankcammer Posted April 18, 2015 Share Posted April 18, 2015 OK, the money shot. This pre can be purchased as an un assembled kit or pre-assembled from TS. I purchased the unassembled kit. If anyone here thinks for one moment that I assembled this myself, you're gravely mistaken. This is Maynards craftsmanship. He did a stunning job and I'm extremely thankful I sent it to him. During assembly, he found that one tube had a dead leg and the two others were marginal. I never would have caught that. I contacted TS and was told that Maynard measured some anomaly and that the tubes were fine. I took the "tube fanatics" word for it and ordered 3 more tubes of the same number and manufacturer as what came with the kit. These tested perfectly and then the entire unit now scoped perfectly. I'm really glad I know my limitations and had Maynard build this. Carl, That soldering and wire run is the best looking piece of the whole project!! Rog Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted April 18, 2015 Author Share Posted April 18, 2015 You're right Roger. If I would have had built it, I never would have posted pictures of the guts! 1 Quote Link to comment Share on other sites More sharing options...
Moderators dtel Posted April 19, 2015 Moderators Share Posted April 19, 2015 That looks great, very nice work by Maynard, very neat and clean looking, perfectly matches the overall design on the outside, straight to the point. Glad you like the sound, for a 3rd and bedroom setup your doing it in style, very nice. Quote Link to comment Share on other sites More sharing options...
justinsweber Posted April 20, 2015 Share Posted April 20, 2015 (edited) Great looking gear. GD is a well thought of topology. Edited April 20, 2015 by justinsweber Quote Link to comment Share on other sites More sharing options...
wvu80 Posted April 20, 2015 Share Posted April 20, 2015 (edited) During assembly, he found that one tube had a dead leg and the two others were marginal. I never would have caught that. I contacted TS and was told that Maynard measured some anomaly and that the tubes were fine. I hate it when someone tries to BS me like that, like I am stupid and will believe whatever they tell me. +++ Edit: I just saw your other post further downstream, where you rated the kit: A 1 in customer support. Agree. Edited April 20, 2015 by wvu80 Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted April 20, 2015 Share Posted April 20, 2015 Nice addition and great craftmanship by Maynard. I wonder how will you know if one tube is out or going bad. I have thought this about my tube amp. I am a total noob when it comes to tubes. Quote Link to comment Share on other sites More sharing options...
erik2A3 Posted April 20, 2015 Share Posted April 20, 2015 (edited) Justin: "GD is a well thought of topology." Not sure what you're referring to as GD. Without getting into the specifics of the circuit, "Grounded Grid" (also sometimes more quickly referred to as GG) designs have their origins, as indeed does essentially all vacuum tube audio, in high speed radio applications. The Grounded Grid preamplifier is the designer's (Bruce Rozenblit of Transcendent Sound) second linestage to made available to the public, the first being a dual output impedance (both high and low) preamp using somewhat more common approaches to circuit design. This first one was published in Glass Audio Magazine in the early 90s, and was when I first stumbled upon it and built it at that time from the published schematic. This was before Transcendent Sound made kit offerings. It's also included in his first book, along with those products more specifically associated with him -- the vacuum tube output transformerless amplifier, or OTL. The Grounded Grid preamp, of which I have built several, is both capable of quite wide bandwidth, and as Carl indicated, is extremely quiet. Much of that quality is due to the simple but effective technique of locating the power supply on one side of the chassis (in this case to the right in Carl's picture) and the signal circuitry on the other. Note the lack of shielded cable, which is just not needed. Transcendent Sound has yet another preamp/headphone amp designed for extraordinarily low output impedance and the ability to effectively drive long lengths of IC. It is based on the 300B triode, and is now in the first stages of construction on my workbench. My amazing wife bought it for me as an anniversary present -- with little time these days to work totally from scratch, which I prefer, the pre-punched chassis is a very welcome thing! This design is largely a point-to-point affair. See here -----> http://www.transcendentsound.com/Transcendent/Masterpiece.html Carl: the next time you take off the top panel of the GG, add a small dab of JB Weld epoxy to the sides of those nuts (keeping the epoxy off the threads of the machine screw). It will prevent headaches in the future. I have built many TS products for myself and others (absolutely zero connection with the company other than being someone who appreciates truly clever and innovative designs!) and have never had any of those come loose or fall off. Edited April 20, 2015 by erik2A3 Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted April 20, 2015 Share Posted April 20, 2015 I wonder how will you know if one tube is out or going bad. I have thought this about my tube amp. I am a total noob when it comes to tubes. Derrick, to answer your question, I don't believe in tube testers but find them useful for picking up obvioius issues. That was the case here. The three tubes furnished were JJ ECC82s which are dual triodes with both sections having the same characteristics. All three had problems in the same section which suggests a bad production run. With one tube, the section was barely functional. The other 2 had significantly decreased output from the same section. One test which I run is to reduce the filament voltage by 10-15% to see how the tube's output holds up. With good, robust, tubes there is virtually no change. In this case, the emission of the tubes (including the "better" section of each) dropped like a rock. In addition, the longer plate voltage was applied, the lower the output became. When tested in-circuit (fortunately, the preamp has a regulated filament supply to keep the voltage constant, so that isn't an issue), one channel had much lower output than the other. Since the preamp uses a single volume control, and doesn't have a balance control, this was a problem- the soundstage was shifted to one side as expected. At 2V out from one channel, the difference was around 0.3V if I recall correctly. At higher output voltages, it increased to 0.5V. This is totally unacceptable. To make a long story short, Joe at Tube Depot was able (for only $2 extra per tube) to supply 3 tubes (also JJs) with both sections of each tube matched, and all 3 matched to each other. Decreasing the filament voltage of these resulted in only a trifling decrease in output. And it made no difference how long plate voltage was applied- output remained constant. Once installed, the preamp was terrific, and furnished excellent channel balance. The big disappointment here is that Bruce, Transcendent's owner, brushed this off. When you consider that he's not paying more than $4-5 each for those tubes in the quantities that he purchases, replacing them should not even have been a thought. If the defective tubes were used in a factory built unit, the owner certainly would have been dissatisfied with the performance and would probably tell others not to buy one. In any event, the circuit itself, as Erik stated, is excellent. Bandwidth is huge. I stopped testing at 50 kHz which still showed an amazing square wave. In fact, it looked better than many other preamps show at 10 kHz. Frankly, I've never encountered a preamp which measures this well. All Bruce needs to do to make the unit really top-notch (in addition to furnishing good tubes!) is to use separate volume controls for each channel, or a balance control. Given the extra three bucks that it would cost, it should be done. Maynard Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted April 20, 2015 Author Share Posted April 20, 2015 Nice addition and great craftmanship by Maynard. I wonder how will you know if one tube is out or going bad. I have thought this about my tube amp. I am a total noob when it comes to tubes. Excellent point Derrick. I thought long and hard about building this myself. I am a tube noob but I can solder and the directions are supposed to be very straight forward. The thing I couldn't get past was the fact that if I had an issue once it was built, who would I turn to for help? I have a DVOM but no way whatsoever to test anything myself. I'd have to find someone, pay to ship it there and back and pay for repairs. I never even thought about the possibility of a bad tube or two rather my workmanship (bad solder joint) would cause an issue that I'd never be able to figure out on my own. I'm glad I came to my senses and put the assembly in the hands of someone who was MORE than capable of building it. I listened to it some more yesterday and am thoroughly enjoying it. Thanks again to Erik for pushing me in this direction. 1 Quote Link to comment Share on other sites More sharing options...
erik2A3 Posted April 20, 2015 Share Posted April 20, 2015 (edited) Maynard: I agree on the dual mono pot approach. In fact I had done just that on more than one GG in the past, and in one case, used two linear taper pots for input level adjustment for each channel (for balancing gain in cases of mismatched tubes), both of which in turn were fed to a single audio or log taper stereo volume control for day-to-day volume adjustment. This put a total of four pots through the front panel, which takes careful machining so they all match. Obviously it can be done. Some people really don't like to hassle with two potentiometers, though, so whether or not two mono controls vs a single stereo can be considered an improvement would really depend on the person. That you and I both prefer that approach does not in my view make it something he should necessarily implement. In terms of performance this preamp is absolutely good enough to be used in any primary system. Glad you enjoy Carl, and Maynard did a nice job for you! Edited April 20, 2015 by erik2A3 Quote Link to comment Share on other sites More sharing options...
Marvel Posted April 21, 2015 Share Posted April 21, 2015 My jma Merlin has l/r adjustments with a third dual. Absolutely a great feature. I would love to hear (or not, as the case may be) one of these. Bruce Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted April 21, 2015 Share Posted April 21, 2015 listened to it some more yesterday and am thoroughly enjoying it Enjoying the music without worrying about some of this stuff make for a pleasurable listening experience! Quote Link to comment Share on other sites More sharing options...
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