I have had a VP-845 for a couple of years and I have learned a few things about this amplifier (not everything). I'll cover some bases. For the 6sn7 NOS tubes I have only tried RCA GTB black ladders and Sylvania chrome dome black base green print. While they were nice, much to my surprise the Shuguang 6n8 offered a more dimensional performance. It came time to replace these and I purchased (off ebay) some Shuguang 6n8 T which is supposed to be the top grade of this basic tube $25 for the pair. I got the same results. This tube works very nicely in this amp. I replaced the output tubes with Shuguang 845b tubes and these are quite nice, doing practically everything better than the basic 845. The stock Shuguang 12ax7 is......junk. I had the opportunity to try several current production 12ax7 tubes because a friend has a preamp that uses these and he has LOTS of current production tubes. I found of his tubes the Tung Sol Russian made 12ax7 sounded best. Now, I am using Psvane Treasure cv-181 for 6sn7 duty and Psvane Treasure 12ax7 in my amp and they handily stomp what I was using before. Greater transparency yet more liquid and luscious.
Regarding bias, there are 2 adjustable pots on the inside of the amp. Leave you speakers hooked up, tip your amp on it's side and place something solid under the transformer so it doesn't tip over. It should be pretty solid now. Remove bottom plate. Locate the pots. The bare shafts are small and slotted. Get a small screwdriver with a PLASTIC OR RUBBER handle. Turn amplifier on and let it warm up for 30 minutes. Now keep in mind that you need to be VERY careful when working in the amp because there is voltage inside of that thing that is as high as 1000 volts and the could very easily be fatal. The left channel pot is on the left side of the amp. Listen VERY closely to your left speaker. Adjust pot back and forth until you find the spot with the LEAST amount of noise (buzz, hum, hiss). Repeat with the right channel. Shut the amp off and reassemble. It is not a bad idea to do this whenever you change output tubes. One last thing; before putting in the 845 tubes lightly polish the pins with 2000 grit paper. Clean the pins with a 90% or greater solution of alcohol. LIGHTLY (and I mean lightly) coat the pins with Permatex Dielectric Grease. WITH THE AMPLIFIER DRAINED, OFF AND UNPLUGGED clean the 845 sockets with a Q Tip and alcohol. Let it all dry and reassemble. The alcohol and Permatex works for the other tube pins and sockets too. Just remember, too much and it will cause sonic degradation. A SUPER thin coating on JUST the tube pins will due. |
To hijack an old thread, I have to agree that the Chinese Shuguang 6N8 (6SN7) is a damn nice sounding tube in the VP-845. I got into "tube rolling" pretty hot and heavy for a while with this thing; using old used, NOS, the ones that people recommend. Much to MY surprise, I keep coming back to the stock Chinese Shuguang 6N8. When the best sounding brand of tube in your amp is still in production and costs $20 - $25 a set, that's a pretty good problem to have! |
What year is your VP-845 Rdk845? |
I have an older version of dared 845 and have been contemplating about getting 845M. But I was worried about low dissipation power rating of 845M than stock 845. Ken do you see, any redish glowing on the plate of 845M on your dared under room light off? thanks. |
Ok, Thanks. I'm just going to spend a couple hundred on some pairs of 6sn7's and see what I like best. I'm going to get the 845's upgraded first so I can see which 6sn7 I will like best with them. I'll update what I'm buying. Thanks.
Brian |
YMMV...(Your Mileage May Vary)..basically how and under what circumstances you drive your vehicle may be different than someone else.. car for same car...your gas mileage may be different...thus the analogy... what works and sounds good to me may not work or sound good to you. :-)
BTW..I am playing the Raytheon short bottle 6SN7's. They are superb sounding. Sweet mids and top with bass almost deep as the KR..but tighter. I think its a winner of a tube. On the Gon right now for $49.00 a pair and a bargian at the price.
Cheers,
Ken |
I'm using a Miova (canadian) power cord. It cost me $50 plus shipping and is quite impressive. I have other more expensive power cords that don't compare. The locking interconnects are also very nice and sound great. Thanks for letting me know the status on your 6SN7's. I'm looking at a matched pair of KR and TS on ebay right now. The TS's are NOS and the KR look nice and are possibly NOS. I'll test them when I get them to be sure they are in good working order. Check out this ebay auction (Item number: 230112569253).
Also, whats YMMV???
Thanks,
Brian |
Telefunken 6SN7GTA [PHOTO HERE]
[GT: ??? GTA: top getter, white labels on glass, black base, round mica with diamond points scattered around it]
GT: This tube certainly lives up to its legendary status. Why? Because it never existed. 6SN7s were NEVER made by Telefunken.
This tube is always sourced from Philips Holland (which in turn sourced from 1960s East German or Russian factories) Also occasionally rebranded as Ultron and Hoges.
GTA: This tube, while labelled Made in West Germany, was almost certainly not made in West Germany. Most who purchase this tube have been disappointed with its sound, describing it as boring and dry (AA).
This above is from Head-fi site..Yes, tele did not make a 6SN7. |
Brian,
Both the KR and TS are already sold..But im curious regarding the Raytheons when they arrive I'll let you know what I think of them..I also tried RCA Gray Glass VT-231 and some Short bottle Sylvanias some time ago..sold them too. Just wasnt right in this amp. I sure would like to try the famous TS round plates, but I wont pay that kind of money just to try them. Dont know, but seems the stock 6N8 are good enough leaving alone as long as you change the other tubes. as I did..this works for me. YMMV of course. What PC are you using on the back of the amp? |
You suprise me by saying the china 6N8 is one of the best you have heard considering all the rave reviews the Ken Rad's and Tung Sol's get. Would you be willing to sell your Ken Rad's or Tung Sol's? Email me at: [email protected] if you would sell them. I'd offer you a fair price or just let me know what you would want. Also, I read that there is no such thing as a Telefunken 6SN7 so what are people selling on ebay??? Two places stated that Tele never made a 6SN7 tube EVER. Makes me wonder. It looks like you have tried about all the tubes I want to try. If you are not interested in selling them to me, maybe rent/loan them to me? I could pay you and use them for a day or two just to see how they each pair sounds. That way I can base my decision better. I'd take really good care I promise! White gloves and all! :) I know it's a long shot but let me know. Thanks. Brian |
Brian..No mods. None planned. Love the sound just as it is. I run a Melos Phono pre amp into one of the line inputs. If I ever got a sub..I'd run it off the speaker level, so not concerned about a line sub out on mine.
I saw your other thread regarding 6SN7 input tubes. Ive rolled Tung Sol Tall Bottle GTB Black base...To polite for me....RCA 5692 Red Base were very airy and smooth as silk, but bass was way too light....Ken Rad Black Glass had killer bass and mids and wasn't bad on top..I could live with this tube, but I found that the stock Chinese 6N8 is by and away the best so far. It has drive and dynamics and very good bass. Halographic more so than any other Ive tried..so I keep coming back to these. I figure they knew what they were doing when they used this tube. That said, I have a pair of 60's Raytheon Short bottle clear glass on the way to try.
My biggest change came from the 845M's and a pair of 50's Tung Sol 12AX7 that came from a Fender Tweed amp. Really textured and musical. This is my current and best sound so far.
Best,
Ken |
All I ever hear is good good good news about ALL 845 metal plates and the Super TNT (Supertnt.com) has a pair for a great price that gets rave reviews also. They released a 845W and not much info is available. I really want to know what it is since they don't cost much more than the 845M. I'm not about to pay the rediculous asking prices for the NOS RCA and United Tubes people are asking. It's getting to be crazy! I've wanted an 845 SET amplifier for a while now and have been folowing the RCA 845's for a while. They were half what they are now 1.5-2 years ago. Do you have any modifications dome to your VP-845 such as adding an output or bypassing the oem control knobs? I was considering getting the Dare MC-7P Preamplifier and bypassing the oem control knobs. My main reason for wanting this is the phono input section. Well, thanks again Ken for the info. If there is anything else or a fun fact about the VP-845 you think I should know, please feel free to post again. Thanks!
Brian |
Brian,
Yeah, I have the 2006 VP-845. Its about 7 mos old. I emailed Dared US and Joe answered to say that the 845 models are self biasing. Yes,I have the 845M metal plates from Sophia. Dont know about the Super TNT as you mentioned. Unless this is the same tube...im not sure as I haven't seen that particular designation..I have not noticed any loss of power compared to the stock 845 (which have graphite plates for comparison)..In fact the metal plates seem so much more alive and coherent with truly great mids compared to the stock tube. Everything seems much more musical and dynamic with the metal plates. |
Thanks for the bias info Ken. I appreciate it very much. The Sophia Electric webpage sells Shuguang 845 Metal Plate tubes, is this what you have? Are they the same as the Super TNT 845M? I'm not worried about a loss in power, but really am focused on getting the cleanest purest sound possible. I'm assuming you are running a Dared VP-845 as well. Is my assumption correct? Thanks.
Brian |
Brian,
The bias is self adjusting on this amp.Not sure about the difference between those tubes. I have the metal plates from Sophia Electric and absolutely love them..much better across the board than the stock 845 IMO.
Ken |
