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There's a new hombre on the horizon. And my trigger finger is really itching to pull. A preamp that has phono with gain controlled by a tube. And tube rectification. https://www.transcendentsound.com/slider.html I had resisted pulling the trigger on his prior phono pre because it had so much gain that with my set up would necessitate adding volume pots for gain attenuation on each channel of it. Rozenblit is known for innovation and dependability with his products. I can attest to that. I've used his OTL and preamp for decades now. The preamp, the grounded grid I cobbled together from plans from one of his books. Which makes it a rather sentimental attachment for me. But I can use it with my old Hafler 220 amp and my 1st speaker build, Dynaudio Gemini's. This ought to be quite a change from the Graham Slee phono I've use for decades too. Fate made me wait with his former phono pre. Had to have a new hvac system put in. Guess the fickle finger worked. Ready, aim....
That looks really sweet! If you do pull the trigger, please write back. Maybe even do a build thread!
Hi, Yes some feed back would be nice. The write up makes me want to mention something about signal to noise. I notice that the preamp is listed as DBA for S/N. This is a common way to do it but..... it might not tell the whole story. DBA uses a roll off for noise below say 200 HZ and is really steep below 50HZ. I personally prefer DBV. That is flat without any roll off. At about 20HZ the difference is about 40 to 50 db. So at 20HZ a device with a -80DBA S/N could actually have only a S/N of -40 DBV. Since the DBA curve is supposed to be related to the sensitivity of our hearing that may not matter to most folks. I personally have the feeling that low frequency junk can alter the quality of the sound. I was really chagrin when I measured my pre-production tube phono preamps at -53DBV at 20HZ. The DBV for 300HZ and up was -93. A less scrupulous designer would say fine -53 DBV at 20 is about -90 DBA and let it go. Not my style. I thrashed it and made several changes so that at any frequency below 300HZ it was at -80DBV and still at -90 to -95 above that. Is it quiet....yes indeed. So my message is beware of specifications and know what they mean. I encourage folks to listen to devices and determine if they are suitable and pass on the numbers.
Never noticed any spurious noise with the two older designs I've used for some time. From his website he has a line stage product called the fixer that the specifications list noise as less than 200 microvolts unweighted. Is that the same as what you mention? Anyway, based on the products I've used for so long and his strong reputation in the diy community for integrity I don't feel too insecure that this product will be anything less than the write up says. Guess I need to pull that trigger and find out. Final cost with tubes is going to be around $750. The one tube it's built around, the 6386 is a pricey little buggar. Around $125.
I took the comments on S/N to be more about dBA versus dBV and less about the device. I kinda have a feeling that preamps from both Bruce's are pretty stellar. Both are passionate men making the best stuff they can make. Such good stuff!
Absolutely. I've no doubt about the veracity of both designers. Both have my admiration as creative craftsmen, even artisans depending on how looking at the audio business. I just know Rozenblit from using his products and having a bit of home town pride of someone making a small mark in the audio field that lives a few miles away from myself. I don't detect animosity, just some professional throw down. I've read enough peer debate, here and many other venues and disciplines that it's all part of the make up of experience and interpretation. Healthy stuff.
Hi, I never intentionally disparage other designers or builders. Doing so has IMO no value. I just wanted to point out that there are different ways to indicate performance and that the ultimate decision for getting something ought to be by listening to it. I figure if the person getting it is satisfied then all is well.
I ordered it and I will post pics of it's innards after I get it soldered. And how I interpret it's contribution from what I used for so long. Have to wait for his delivery he said. He's swamped with orders. He's a one man band. I'll get personal delivery from the designer himself. This forum seems to have the dog days of summer with a covid twist going on. Not much activity.
That's awesome, Rusty! Can't wait to see pics!
A knock on the door and a delivery personally via an electric bicycle with a newsboy basket on the front. On my front porch, a pony tailed gent that looks to take care of himself. I'm in the presence of an eccentric creative genius. I call him now, The Wizard of Waldo. Waldo is a section of the city developed in the 1940's when it was a suburb. The wizard is Bruce Rozenblit. And the box of wonder within the shipping box. Putting in the hardware. A dainty handed lady could have done it in a half hour. But an aging wiener fingered guy like myself took hours. About halfway done, whew, doing point to point wiring is time consuming and sometimes exasperating getting wire crimped over the solder lugs. It's been close to 20 years since I'd done anything like this. It becomes a learning curve again with the soldering skill. And...those wiener fingers again, makes things much harder. That's all for now. I'm taking my sweet time. I can't sit for too long with a furrowed brow.
Man, that looks good, Rusty! Thanks for sharing your build with us. I love it!
Nice progress Rusty... especially with wiener fingers. Interested to know how you like the sound once you've run it in for a while...
Whew! Done wiring...Finally. Did a cursory look over and called it a day. I'll go over everything this week. Soldering looks shiny enough, though sometimes I glommed a tad much. Soldering is a skill set that takes sheer volume of tries. I got much better towards the end. I'll go over everything and if all's well, button it up, put the knobs on an fire it up. Hoping against yet still, did I mess something up? That's what fuses are for. There are no fancy audiophile parts within, which a trained eye could tell. But, that's the philosophy of the designer. I'm alright with that.
Wow! Looks great!!! Fingers crossed on the initial power-on...
Still wondering how this turned out for you Rusty? I just finished, and am running in a pre-amp kit of my own from VTA...
Hey JC5. I've been chasing a buzz. It's got to be a bad solder weld. I've been over all the hookups and placements of parts, which seem to check. I'm just going to have to go over the solder joints with the iron. Which is hard for some of the occupied terminal strips. I'll have to undo the connecting screws to let me get at them better. Point to point build seems much more difficult than I'd anticipated. Circuit boards are much friendlier to solder. But I remember I had this problem with my original Grounded Grid preamp I built from schematic. Once I got the one little connection stuck tight, it was silent as an owls feather. Real frustrating though until then. How do you like your build?
I think reflowing all of your solder joints can be a good idea/approach. It worked for me in the past for correcting a problem (oscillation...). I agree It is much easier on a PCB though. I am enjoying my new preamp (VTA sp-14) and it seems to be burning in/mellowing out quite nicely. I was a bit unsettled at first, as it seemed a bit bright and strident. That was not an effect I had from any previous DIY preamp builds I'd done. It's as quiet as a church mouse lol. Seems to have a little bit more gain than I'm used to or need though. It wasn't my first choice, and a bit more $ than I was looking to spend, but It satisfied the "DIY" itch...
Fingers crossed. Noodling around, moving a terminal out from it's location a film cap leg from the gain pot just popped off from the terminal. It was a stretch originally getting it to span to the terminal, so I added some wire from it to the terminal. Later I checked one heavily populated terminal for the phono section that was very unfriendly getting it fixed back to the case. I must have spent 45 min to an hour trying to get a teeny lock washer and nut back on to the screw. I felt like Curly from the 3 Stooges, exasperated at doing the same thing over and over with a pair of needle nose pliers with a bit of magnetism holding on to the little parts when I didn't want it to. Yup, I'm paying my dues getting this thing to play right by me.
Hi, it is a bit difficult to see but it appears that all the input wires and output wires are not shielded. I have found that any time one needs to be longer than about 2 inches they have to be shielded to prevent hum. If you replace them with shielded wire remember to only ground the shield at one end unless it is actually carrying the ground return of the signal.
Guess he designed it that way Bruce. No insulators for the input/outputs, no ground ring for the outer sleeve. Guess the case carries the ground return. No shielded wire included in the kit. I emailed him about this hum/buzz. He says I must have an open or bad ground in the power supply. I thought I had it when the little film cap leg popped off the terminal, but, nope. No cigar yet. Very frustrating. His products sound great. So I figure it's my bad soldering skills.
Hummmm. I believe I would upgrade it to shielded wire regardless, just because I am a fanatic about hum and noise and any at all is too much.
After you finish this project (or before, for that matter), if you want I have some shielded cable that I used when I built my IR Remote Passive "Preamp" prototypes way back when. Just ping me if you want ten or twenty feet of the stuff and I'll mail it to you.
Thanks both of you and Wayne specifically. Where would the shield portion go? Some ground point on the case? Still though, the design doesn't use shielded inputs or outputs, or sleeve ground. Just the single wire to the center tip. I'm not sophisticated enough to know his justification. Any idear's? If this is a chronic dilemma I'm facing. Reckon I'd give anything a try. The noise is constant, on all switched inputs, doesn't go up in loudness with volume control, or gain control. Thanks for any tips.
Connect one end to ground, whichever side is most convenient. Just leave the other end bare - Cut back the shield braid right along with the outside jacket. You might even put 1/4" to 1/2" of heat-shrink tubing over the edge where the outside jacket ends, to cover the frayed edge of the shield braid. That way the shield is grounded, but no ground loops are created 'cause it's only connected at one end.
I did all that my meager knowledge and skills allowed. The last effort was to try a cheater plug and see if that broke the ground loop. It's in the shop with the master. He said he'd fix it. It'll be interesting to find out what the hell I did wrong. Probably something very elemental. But it escaped me going over what I did.
Finally got it back today. No charge. He said he'd goofed and left out this one last instruction from the manual that was a ground wire from one of the tubes filament. No one had pointed it out. It appears in the finished wiring picture, but I never noticed just following the instruction steps. No fault of mine. It's dead quiet now he said. And he said I did a pretty good job wiring up everything, and that he'd seen units people sent in that parts were falling out opening up the things. I'm honored. Anyway I'm too damn pooped to pop getting it set up now. I finally finished raking and mulching leaves and I need a beer and an easy chair. Yes tunes would be nice. But I'll find out tomorrow what I've been missing. The man knows his stuff, so I guess the case carries all the grounding duties. Shielding cables not needed. Hot diggity! I'll do a little write up on what I think.
Wow, man, awesome! Congratulations, this is huge! And kudos both to you and to Rozenblit. You did a great job building the kit and Bruce did a great job supporting you. Round of applause!
Good job Rusty! Let us know how you like it after listening for a while.
I really like Wayne's last reply. It looks like a shot from the Guinness Book of World Records "Speed Clapping Competition"
Johnnycamp. I think of those old timey silent movies where everyone moved in double time. I can tell you that from my preliminary listening, this thing is a joy to behold. I haven't formulated yet how to express it in words. Just more and more of what I have enjoyed from his older products. Which I understand now why this replaces two of his legacy preamps, the grounded grid line preamp which I've used for years and the phono preamp. I'll try to do a coherent sort of short review without audiophilic blather triggering a gag reflex. Hate that crap.
My review at long last. Drum roll..... crickets chirping. I found something that seems to accurately and visually accounts for what I'm enjoying from this line preamplifier with phono circuit built in. This is from a Danish speaker builder whom has tried a couple of Transcendent Sound products. Here he remarks about the prior phono preamp that the new Slider line preamp replaces. His remarks: Above the perceived soundstage from these experiments. When we did the Densen/Transcendent comparison we first listened to the Densen and then the Transcendent and my guest bringing in the Densen said: "See, a wider soundstage!" And yes, I too hear a sort of wider soundstage, but at the cost of the holographic and expansive midrange good valve stages can create through good high-efficiency speakers (DTQWT in use here). From Densen and the Jasmine I hear a somewhat compressed midrange, very cool, very clean, but nevertheless without the transparent, almost "reach out and touch" properties of good valves. I suspect this might be what Johnnycamp is experiencing with his new preamp. And will be the same with Bruce's phono preamp when made publicly available. This seems to sum up what I'm hearing better than any gushing prose I can write. It was quite a change from my Graham Slee preamp with the volume setting I typically used. Going above 9 or 10 o'clock would make very loud music. The prior Transcendent phono pre was too hot to put in my system. When this new rig became available that sealed it. Now with a gain and volume setting to use, I'm typically putting the volume control around 1 or 2 o'clock and just bringing the gain setting up to about the 9 o'clock range for typical listening levels. I get better channel balance, just like the man says in his write up. What he states is right on. Now, I guess I'll try out some different 12AX7's and hear what gives.
That's great Rusty! Congrats! That is the impression I get from tube preamp vs. ss preamp. My VTA sp-14 also has left and right gain knobs, and then the master volume. Its a high gain pre-amp (19db). In my system the left and right gain knobs are set at 3:00 and then the master is at around 1:00-2:00 for around 80-85 db..
I like supporting these independent audio entrepreneurs that maximize the end users resources, (their labor), to bring high end to the masses. They're doing it for the joy it brings them and a little bit of income to lead a life of their own without kowtowing to a corporate entity. Frequently and probably to a higher percentage so, they innovate and push the envelope of the craft that can't be replicated by the big players without a commensurate inflated price tag. Years ago after out of curiosity trying out a subscription to Audiophile mag, just to get a taste of what this high end was about. I happened on to an article/ review of Rozenblit's first commercially available OTL amp. And he was based in my home town. The review was praise worthy as the reviewer ended with, "penciling in" about obtaining this amp. This was the beginning, and end to any commercial audio magazine review of his products. I figured it was his confirmation of acceptance by the ordained audiophile community that his products were viable. But, I reckon from there is where the concept of a small diy kit manufacturer and a pay to play requirement of the audio review process ended. Thus henceforth his products never made the recommended list of that publication. When I picked my unit up from him after he fixed his error in the instruction manual. He told me after I asked if and when he might retire. He said, he'd keep on until he wasn't capable of his standards mentally. And that, as a business venture he could probably make as much or more working at a hardware store. He had worked as a consultant in the power industry. It was luck I found out about his little company. Only through an audio rag that other than my finding out about a valuable resource for great audio at sanely priced products, most of what your paying for is prestige and pretty casework with usually ordinary circuits residing within. I let my subscription to Audio-vile lapse after one year.