@
kentrent
Do you have the manual for the preamp?
https://audioresearch.com/ar-package/ls15_manual-pdf/
Do you have the manual for the preamp?
https://audioresearch.com/ar-package/ls15_manual-pdf/
Audio Research VT100 MK1 and LS15 HELP!!!
I recently bought this set VT100MK1 and preamp LS15 and while I was at this seller house he demonstrated the sound from his online Tidal on TV connect optical to the DAC Luxman DA - 06 then this go to the preamp LS15 and out into the VT100. This set up sounds amazing at his house. However, when I came home play CD from the Sony X1100ES Blu-ray player RCA output into the LS15 and out to the VT100 and it sound horrible - no bass at all in any type of music. The sound sometime muffle and not clear and most importantly the bass missing tremendously. Im using a pair of KEF R900 Speakers. What is wrong here? can anyone help me correct the sounds? it is because I didn’t have the Luxman DA - 06 DAC? or it is because I don’t have those fancy hundred - thousands of dollars cable? or the CD source is playin at 41khz /16 bit not high enough signal?
This is my first system and I don’t know why I can’t get that high fidelity sound from the ARC equipments. I'm waiting for the Audioengine B1 to arrive so I can stream Spotify into the LS15. What is wrong with my set up? Thank you in advance for helping me solve this.
This is my first system and I don’t know why I can’t get that high fidelity sound from the ARC equipments. I'm waiting for the Audioengine B1 to arrive so I can stream Spotify into the LS15. What is wrong with my set up? Thank you in advance for helping me solve this.
Showing 12 responses by jea48
almarg8,964 posts @ kentrent If you pull any of the tubes from the VT100 make sure the tube goes back into the same exact tube socket the tube was removed from. Exactly the same tube socket. Especially the small 6922 signal tubes. Failure to do so can cause damage to the amp. The 6922 tubes are biased for the circuits they are installed in. Also before you pull the top cover unplug the amp from the power wall outlet. Let the amp set for about a half hour to allow the high voltage electrolytic caps to drain/bleed off. The DC plate voltage for the power tubes runs about 450 volts DC. Did the guy you bought the amp from tell you about how many hours are on the 6550 power tubes and the 6922 signal tubes? If not you need to find out. 6550 power tubes have an average life of 1500 - 2000 hours. The 6922 tubes average life around 4000 - 5000 hours. Jmho, you are not knowledgeable, experienced, to replace and bias the 6922 tubes. You will need to pay to have it re-tubed by a professional when it comes time. Total retube of VT100 Mk 1 & Mk 2 http://mycollins.net/audio/artube1.html ~ As for the speaker jumpers. Can you here any bass, music, at all coming from the bass drivers? Jim |
kentrent OP12 posts Are you 100% sure you have the speaker cables connected to the VT100 amp terminals correctly? ( 0 ) is common, neg ( - ). Make sure both speakers neg ( - ) is connected to ( 0 ) common on the amp. Pos ( + ) on the 8 ohm or 4 ohm terminal on the amp. Verify 100% you have them connected correctly. Also make sure the interconnects are plugged in all the way. |
kentrent OP31 posts In your case, imo, no kentrent OP31 posts The preamp protection circuit was/is shutting down the unit.I would not power up the preamp again until you install the new tubes. Hopefully the bad tube didn’t take out a resistor. As for why the 6922 tube shorted, went bad? I have had new 6922 short after just a few hours of use. It happens. Just curious approximately how many times have you turned on, and turned off, the preamp since you brought it home. Repeated power up can cause stress on a tube. Did you read the owners manual for the preamp? |
Same set up, I switched out the arc and use the mac1500 and has a lot of bass response especially low. Switched back to arc and it has about 60% decreased in bass. All speakers wires are all properly connected. Can someone here explain this? https://classicreceivers.com/mcintosh-mac-1500 http://sportsbil.com/mcintosh/Receiver/MAC1500/MAC1500_ser.pdf But what about the LS15 preamp? You didn’t just switch out the VT100 amp. You switched out the preamp, amp, and balanced ICs. Just curious, what do you have the tone controls set at on the MAC receiver? Flat, ( 0 )? How about the loudness button? In, on? Out, off? You need to find someone to come into your home to help you to resolve your problem. |
chip_29508 posts If not, steal a 6922 from the VT100. It has 8. Bad idea. If the 6922 tube is damaged he will have a bigger headache than he has now. First he will have to buy two new closely matched pairs, and I mean each section of each pair closely matched, 6922 tubes and pay a qualified Tech to re bias the 6922 tubes in that channel of the amp. |
@almarg No Al, I was wrong. The bad thing is I knew better, LOL.... Like I said I must have had a brain fart moment. Here is a picture of the back of a VT100 https://www.google.com/search?q=audio+research+XLR+single+ended+shorting+jumpers+for+vt100+power+amp...: Note the printed picture beside each XLR input connector showing the correct jumper install position for the jumpers. Edit: No excuse but I know where I went astray, LOL....... chip_29508 posts Jim |
chip_29508 posts@chip, Thanks for the shorting pins info. The OP is using balanced ICs. But with that said are the jumpers removed? ~ ~ ~ @almarg, What if the jumpers are still installed? The OP is using balanced ICs. Would the jumpers not be shorting out one side of the balanced outputs of the LS15 preamp? That might explain why the OP said he had to crank up the volume so high to reach the desired volume level he wanted. Wouldn’t shorting the outputs cause problems with that section of the balanced output circuitry of each channel of the preamp? Could that cause the 6922 tube damage? Back of VT100 https://www.manualslib.com/manual/907956/Audio-Research-Vt100.html?page=3#manual Al, Here is a PDF for the SP15 preamp manual. Read the warning about muting the preamp with the volume control turn up. https://audioresearch.com/ar-package/ls15_manual-pdf/ Jim |
Just right now, i used another old 80s preamp from Sony and the sound is boomy boost of full bass and tone control was on neutral (imagine if i crank that bass up). So this confirmed the vt100 is working and my LS15 preamp is not giving that sound. Perhaps because of the faulty V3 tube? I already ordered the new tube on the way. I’m hoping replacing this faulty tube will fix my bass response problem. @ kentrent I assume you used RCA single ended ICs to connect the Sony preamp to the VT100. Read my post above ( page 2 ) about if the shorting jumpers were removed on the VT100. If you were using balanced ICs the jumpers must be removed. Back of VT100 https://www.manualslib.com/manual/907956/Audio-Research-Vt100.html?page=3#manual |
kentrent OP35 The jumpers MUST BE REMOVED if using balanced ICs The jumpers Must BE INSTALLED if using RCA single ended ICs. Jim |