Sending Dared SL2000a in to repair hum

Stew

I've seen several threads lately talking about hum in the Dared SL2000a. Mine has always had a slight 60 hz hum but I convinced myself it was the nature of the beast. I tried lifting grounds, swapping cables, tubes, etc. but nothing changed the hum. It's barely noticeable from the listening position but very obvious a few feet from the speakers.

After reading that some are essentially silent, I contacted Joe at Dared for advice. He suggested I contact Mike at Deltronics in Woodridge, IL. I'll box it up tomorrow or Friday and send it in. Unfortunately, the warranty's up so I'll eat the repair bill. My own dumb fault for not dealing with this sooner. Mike will contact me with a diagnosis before making repairs. I'll post his findings when I hear.

I'm also sending the Auricap input caps I purchased but never installed. Mine has the rectangular input caps flush mounted to the board so I'd have to get access to the back of the board to install. Mike said he can install while he has it apart.

audio_alan

Please keep us updated on what happens with your unit. If it does turn out to be a defect, maybe mine suffers from the same thing. My sounds like your's - the hum isn't very noticeable from far away, but up close it's obvious.

As a side note, strangely I was able to get mine to stop humming, but that was when I accidently plugged in a dvd player's outputs into the dared's outputs (instead of the dared's inputs). However, after realizing my mistake and hooked it up correctly, the hum came back (bummer!). I'm wondering if mine isn't just a ground loop problem...

heiney9

I have talked with Mike and bought an amp from him. A local polkie also had a cap replaced in his Dared and Deltronics did the work. They seem to be very good.

Good luck

H9

schwarcw

Stew, do you have an antenna hooked to a tuner or receiver in your system? Or possibly a cable TV box that's connected into your audio system in some manner. These can cause hum!

daboyz

That was my Dared and they did a very nice job. You're in good hands.

audiocr381ve

Please let us know how it turns out! I have one with the same issue, but it sounds like mine is more severe. I hear not only hum, but noise from my computer (on the same circuit), AND I'm running an APC H15 power conditioner.

Stew

H9/daboyz - Glad to know I'm in good hands with Mike at Deltronics. They just called to let me know it arrived and get a deposit.

Carl - I do have a cable box that's connected but I disconnected everything and hooked up preamp, amp, and speakers only - with and without cheater plugs. Still hums when preamp is turned on.

audio_alan, audiocr381ve, etc. - Deltronics estimated 1 to 2 weeks for a diagnosis. I'll keep everyone posted.

Happy New Year!

audio_alan

Good deal, Stew. I hope it works out and the fix isn't too expensive.

audiocr381ve

Any word on this yet?

Stew

I haven't heard anything yet. I'll call next week if I don't hear from them.

erniejade

I live 5 Min. from Deltronics. They have always done good work for me. I have had a lot of boomboxes ( i collect them) on down to my velodyne spl1200 hum fixed there. Nice people there. If something isnt right, don't be afraid to call them either. They will make sure you are taken care of after a repair also.

erniejade

I forgot to mention, if you live in the area, make sure you stop up the street at Holm Audio!

audiocr381ve

Stew wrote: »

I haven't heard anything yet. I'll call next week if I don't hear from them.

Great, please keep me posted! Mine is out of the system until I can fix that hum.

Stew

I spoke to Mike earlier this week. He heard a slight hum but hasn't been able to duplicate what I was hearing. He did find and repair some questionable solder joints in the power supply that could have been the culprit. I'm wondering if he has cleaner power in his shop and therefore less hum to begin with. I'm hoping that I'll hear a bigger improvement.

He's trying to locate an NAD amp so he can duplicate my setup. I appreciate the effort and will wait patiently. I'm really going to be baffled if it still hums in my system! Time will tell. I'll keep everyone posted.

audiocr381ve

Stew wrote: »

I spoke to Mike earlier this week. He heard a slight hum but hasn't been able to duplicate what I was hearing. He did find and repair some questionable solder joints in the power supply that could have been the culprit. I'm wondering if he has cleaner power in his shop and therefore less hum to begin with. I'm hoping that I'll hear a bigger improvement.

He's trying to locate an NAD amp so he can duplicate my setup. I appreciate the effort and will wait patiently. I'm really going to be baffled if it still hums in my system! Time will tell. I'll keep everyone posted.

Bummer, I was hoping it would be something more obvious. Thanks for checking in!

Stew

My Dared is on the way home. Mike at Deltronics checked all the capacitors in the power supply, cleaned up solder joints (power supply, inputs, outputs and volume control) and installed the Auricap input capacitors I supplied. He says the noise floor is within spec and as low as he can get it. He only hears a hum if he's close to the speakers. It should be here Wednesday and I'll be anxious to see if the hum is less in my system. If not, I either missed a ground loop or it doesn't play well with my amplifier. I'll post the results. By the way, Mike charged about $140 + shipping. Seems more than fair for the effort.

Oldfatdogs

I hope your guy got things fixed for you.
His price seems reasonable,how many caps did he replace?
Knock on wood mine is still quiet.Hope yours is too.
Dan

Stew

It arrived Wednesday night and I finally got a chance to listen today. Hum seems a little better but still there.:sad: It's really not that bad but I would like to find a solution. I'm using the amplifier portion of a NAD C370 integrated amp. There was no hum at all when I used the preamp in the C370. Any thoughts on whether a different amp might help?

Dan - He replaced the two input caps with Auricaps. It's been a while since I've listened to it but the Auricaps sound incredible!

soundfreak1

I dont think ANY hum is accecptable. Mine has never hummed its dead silent.might want to roll some tubes just in case. Dont know if they can cause a hum but the unit should not!

Stew

On a whim, I just hooked up my Yaqin tube buffer between the Dared preamp and NAD amp.

In my old system, the tube buffer still passed the signal through when turned off but speaker output was lower. The gain is 1 when turned on.

I first tried the tube buffer between my Dared and NAD with the tube buffer off. The hum is almost entirely gone! I have to turn the volume knob on the Dared up more to get the same volume but there's no hum. With the tube buffer turned on, the hum comes back.

Do I need an amplifier with a higher input impedance? Someone who understands tube buffers/amplifiers better than I do please help!

Oldfatdogs

Dan - He replaced the two input caps with Auricaps. It's been a while since I've listened to it but the Auricaps sound incredible!

Hello stew,I'm glad your upgrade on the caps showed improvement.I would try another amp if you have access to one,cant hurt to try.Like soundfreak, I would roll some different tubes just to see. Wish I could be of more help,Im sure others will chime in here.
Dan

Systems

Have you tapped on the tubes with a pencii when in use?

heiney9

Not recommended to do that!! Tubes and the internals are delicate and should not be tapped, especially when in use. What does that prove anyway? If the the OP hasn't already; you can power down the unit remove and reinsert the tubes, on occasion this will get rid of humming or static. I would assume as long as the OP has had this issue, he has done that and also tried various other tubes to eliminate tubes as the source of his problem. That should be the first thing one does with a tube piece.

Auricaps are simply wonderful. I feel for the guys who bought the later models because they don't come stock anymore. It really improves the performance of the Dared SL2000A

H9

Stew

I've tried it with original and upgraded tubes, cleaned pins, etc. all to no avail. A better wall socket couldn't hurt but it's plugged into a Panamax conditioner. I've tried it with and without the Panamax and it doesn't change the hum.

What effect would a tube buffer that's turned off have? (See Post 20) Would it increase the input impedance? If so, I need to look for an amp with a higher input impedance. Thoughts??

Toolfan66

My dared has never been dead quiet, as a matter of fact I don't think I have ever had any tube gear that was dead quiet except my phono pre.

Not that it was a loud hum on any gear..

zombie boy 2000

Same here. I've owned two Dareds mated with a variety of amps and speakers in three different residences with different tubes and have ALWAYS had a slight hum. Nothing obnoxious. And nothing I can hear once the music starts. Just my experience....

Stew

With the tube buffer in line but turned off, the hum is there but I have to be within a couple of feet of the speakers to hear it. That would not bother me. Without the tube buffer (or with it turned on), the hum is slightly audible from the listening position during quiet passages. That does bother me.

The more I think about the tube buffer in line but turned off, I assume it is effectively decreasing the gain of the preamp. How would I lower the gain of the Dared? I'm not sure I want to do that but would like to know what's involved. The other option would be to find an amplifier that handles high gain better than the NAD. What specs do I look for in an amplifier that will handle high gain? Any brands that seem to handle high gain better than others? Thanks for the help!

daboyz

I'm sorry to say that your Dared is toast and you should just sell it. I'll give you $20 for it.

I'm trying to remember but I had to send it in is because one channel hummed to the point where it was unlistenable. If it's not there when the music is playing then I wouldn't worry about it. The Auricaps are sweet.

Systems

Not recommended to do that!!

My thoughts where the micros......
That said, if there is a major problem doing this........then you have other problems.
Comprende?

audiocr381ve

So I swapped my Polk Monitor 5's for a pair of Magnepan MG10's and can't hear a hum anymore.... Very strange.

The hum coming out of my Monitor 5's could be heard easily from my listening position. With the Maggie's swapped in, the hum is gone.

OP, have you tried swapping in a different pair of speakers?

Stew

I'd be willing to bet the Maggie's have a lower input sensitivity than the Polks. I think this is starting to make sense. From the research I've been doing tonight, a high amplifier input sensitivity (v) requires a higher volume setting to achieve the same sound level. A low speaker sensitivity (db/watt/meter) also requires a higher volume setting to achieve the same sound level. Either will reduce the noise floor.

I'm glad you found a solution but I'm not interested in different speakers. I need to look at the amplifier. My NAD has an input sensitivity of 1.1v. I've seen some amps as high as 1.75 v. Another option might be in-line attenuators (Rothwell, Goldenjack, etc.) but I'm concerned they might degrade sound quality. Any thoughts appreciated.