[darkclouds]

This has got to be the most stunning piece of equipment I've ever owned. Despite it's size, it seems to way a ton.
I can see my own reflection on the mirrored aluminum casing. The 300B tubes are simply gorgeous.

In my haste to set it up, I skipped the manual and didn't realize that each of the tubes' bubble wrap was labelled from VB1-VB6 (4 12au7 and 2 300B). I only discovered this after I have taken the tubes out of its wrapping. A glance at the manual revealed a diagram with tube sockets corresponding to VB1-VB6. Now I'm a bit worried.

On both sides of the amp, there's TP 'plug', Hum and Bias adjustment screw.

In anycase, I plugged everything in. Hooked the amp directly to the 555es and wired the K1000 to the amp's 4 ohms binding post.

The sound? Not like what I had imagined. The combination seems to lack the 'oomph' I was looking for. At low volume, the sound was crystal clear. But I was unable to get the amp up to my normal listening level without getting distortion.

Calling out to Tuberoller or any other tube gurus for help and advise.

 

[darkclouds]

Maybe one of the K1000 owners could help. These are brand new. I've only tested them out on my Zotl which was at very low volume and sounded fanstastic. I'm wondering if the k1000 needed to be burn in first.
Regretably I do not have speakers to test the amp.

 

[Tuberoller]

Hey,

The Sovtek 300B tubes(they are simply relabed ) that come with that unit require some burn in.But I think you may have another problem.please let me know what other equipment you are using with this amp(especially speakers) and how long it has been in use.If it is brand new take it back.Also let me know if this distortion is isolated to one channel and what you consider a normal listening level.


I should have read you post closer.I see that you are using the ASL with a set of AKG.Still I need to know if there is channel specific distortion and how loud you are playing the amp.If my memory serves me I think that the AKG phones require a minimum 7watt amp and the ASL amp puts out 8-9 watts advertised and more like 5 watts measured.sorry for the confusion

 

[darkclouds]

Very nicely done Tuberoller.
I hadn't notice until you mentioned it; it's the left channel that distorts. I had automatically assumed it was both. The distortion is quite noticeable at just past 11 o'clock. The volume knob starts at about 7 and maxes out at about 5.

For what it's worth, the 300Bs are Valve Art and the 12au7s have ASL label.

 

[Tuberoller]

Switch the two 300b tubes.allow the amp to warm up and let me know if the distortion switches channels.

 

[darkclouds]

Well, just hooked up the UHC-signature and tried out it out with my HD600 and got the same left channel distortion. I've powered the amp off and waiting for the tubes to cool down.
I hope I don't have to replace the tubes cause they are freaken expensive.

thanks tuberoller for your help thus far.

 

[darkclouds]

Ok, I've switched the 300bs and the distortion is still coming from the left side. I hope the amp is not defective.

 

[Tuberoller]

I was looking online for a shematic of your amp and have not been able to find one.From what I know about the 300b tube I know that your amp is an SET and the 300b is an output tube.SET amps are very simple to diagnose but I would not encourage this if you are not technical or if the amp is under warranty.Try swapping inputs jacks with your souce and try moving the input tubes.If none of this helps isolate the problem to the input tubes pop off the cover and visually inspect the chassis wiring.i don't know if this amp uses a pcboard or point to point wiring so all can can tell you to do is look for any schaffed,deformed or burned wiring near the transformers,tube sockets or output jacks.I don't think this is a power supply or volume pot problem as it's isolated to one channel.you would be looking for some obvious problem in the circuit for that channel.I could be wrong about all of this because I don't know much about the specific circuit design.If you chose to pop the cover please allow cool down and plate voltage dissipation so that you don't get burned or shocked.please let me know if you find anything.

 

[darkclouds]

Thanks Tuberoller,
I've been switching the input tubes and different rca and switching to the amp's other line level inputs. I didn't solve the problem but has added another one. Now I've lost the right channel and the left one is distorted.

 

[darkclouds]

Thanks Tuberoller,
I've been switching the input tubes and different rca and switching to the amp's other line level inputs. I didn't solve the problem but has added another one. Now I've lost the right channel and the left one is distorted.


Maybe Joe Lau will chime in later.

 

[darkclouds]

Got the right channel back (loose connection). but the left channel distortion is still here.

 

[Joe Lau]

Quote:

Originally posted by darkclouds Ok, I've switched the 300bs and the distortion is still coming from the left side. I hope the amp is not defective.

You should adjust the power tube to proper current ! It is around around 70ma. It may be change pot position when shipping and you also had mixed the tube.

 

[darkclouds]

Can you give me instructions on biasing the amp?
The manual does not mention biasing at all.

Thanks

 

[Tuberoller]

If there is a bias adjustment screw/s there should be a test point or terminal where you would make the adjustment using a meter,sometimes the screw is the test terminal.Joe Lau gave the spec so if you can bias the amp do so.Have you heard of anyone else driving the AKG with this amp?Is this a good match?I really don't know.I looked up some specs for the k1000 and they are only 74db efficient and have a 120 ohm impedance.If the ASL does drive these well I think it is working hard to do so.I am still trying to find a schematic,when I do I can be of more help.

 

[Joe Lau]

Quote:

Originally posted by darkclouds Can you give me instructions on biasing the amp? The manual does not mention biasing at all. Thanks

You can find 3 Holes on both side (Left & Right) of Chassis. it have 3 Hole mark Bias , Hum and TP.

Just behid Front Panel is Bias adjust pot and middle is Hum adjust and the last is Test Point.

You can use a Multi meter to test it. The Black (_) test prob should connet to chassis and Red (+) connect to test point. Adjust the Bias pot around 0.7V (70ma). It will be the correct bias. Adjust both tube to same current. You also can adjust the Hum to minimun by Hum Pot.

Is it well match with AKG1000 ? Yes ! It is good match with AKG1000. I suggest you connect AKG1000 to 4 or 8 Ohm. It will get better result. AKG1000 need low impedance to drive even it say it is 120 Ohm impedance but it is not good sound if you drive it by high impedance. You can found some review on net. I can't remember is it Headwiser or somewhere !