Problem faced with Valhalla2 as pre with Audiolab 8200A as power amp - Help needed

[Kannan]

Your Valhalla is actually under powered to drive the Audiolab and not the other way around.

A tube integrated should be a better option, but Audiolab is a good product and I suggest you think twice before jumping the boat.

It is not always easy to match any pre to a power, specs are a starting point and do not assure total comparability.

Zero gain buffers is a safe route.if all you are looking for is some warmth.

Also you will have to see what power you will need if going for a tube, to power your speakers

 

[Deleted member 15865]

S

Pairing a integrated tube amp becomes all the more critical and very much the power requirements of your speaker will be a very important factor to decide

Jolida comes in my mind if you want something in excess of 20 to 30 watts
Not sure about pricing and other details

Thanks. My speakers - Castle Knight 2 (biwired) which I am happy with. They pair well with the Audiolab 8200A.

Any compatible integrated tube amp suggestions?

 

[Deleted member 15865]

Your Valhalla is actually under powered to drive the Audiolab and not the other way around.

A tube integrated should be a better option, but Audiolab is a good product and I suggest you think twice before jumping the boat.

It is not always easy to match any pre to a power, specs are a starting point and do not assure total comparability.

Zero gain buffers is a safe route.if all you are looking for is some warmth.

Also you will have to see what power you will need if going for a tube, to power your speakers

So, I’d need to look for tube preamp with higher output impedance, right? How much should be min necessary? The Freya has 210 ohms. Would that be sufficient? The Audiolab 8200A’s preamp’s output impedance is 100 ohms. So Freya is double that. Should that be sufficient you think? What other parameters I need to match?

 

[Kannan]

Impedance should not be an issue as most modern SS amps have very high input impedance.

Input/output impedance and input/output sensitivity are some of the main factors in matching pre to.power.
But still some combos may just not work together well while some may go well with one another.

 

[jls001]

Sachin,
I tend to disagree with your final diagnosis about the Valhalla overpowering the 8200. Unless there is a clipping detection circuitry in the 8200 that shuts it down for its own as well as speaker protection when clipping occurs, there is no reason why the 8200 will shut down. It will just clip and produce a distorted sound. As I mentioned before, the problem seems to be lying elsewhere else and not in the gain structure of the chain.

 

[Deleted member 15865]

Sachin,
I tend to disagree with your final diagnosis about the Valhalla overpowering the 8200. Unless there is a clipping detection circuitry in the 8200 that shuts it down for its own as well as speaker protection when clipping occurs, there is no reason why the 8200 will shut down. It will just clip and produce a distorted sound. As I mentioned before, the problem seems to be lying elsewhere else and not in the gain structure of the chain.

JLS, there is a detection circuitry in the 8200A which takes precautionary measure and is shutting down/cutting off. So, can we rule out the overpowering possibility?

 

[Deleted member 15865]

As Joshua stated earlier and I also mentioned, why not get hold of a sensitive multimeter and take some readings ?

Problem could be with a out of spec component in the Pre leading to some voltage leaks or ripples.... Just a wild guess but since the RCA audio output of the headphone preamp is THE source of the problem, then why not take some readings ???

Else, If I were you, I would have done one of the two things:

1. Used a tube buffer before the integrated amp and put the headphone amp on sale.

OR

2. Invested in a Tube Integrated amp, and sold the SS amp and Headphone amp to partly finance the new investment.

How good does this amp look.......

View attachment 28822

Just an example, KT88, PP mode I think, 55 watts per channel at 4 or 8 ohms. Amazing build quality. Just $700 IIRC.

There could be other options too.....

Just some food for thought.

Forgot to mention, I will try to optimize the tube buffer I built recently. Pretty cheap and great value for money. You can give that a try. ( No, I am not into building several of these and make money, I just happen to have built two identical and can let one go at actual costs, I incurred )

Thanks Yogibear. I do intend to get the Valhalla 2’s output checked. Just that I don’t have the capability and equipment for the same. I am locating who can help. I need to ensure they don’t have to open it as it’s under 5 years warranty. And I want to ascertain the problem before sending it in for warranty.

Let me understand the buffer option better. I’d connect with you one on one for the same. And thanks for the magnanimous offer to help out.

 

[jls001]

JLS, there is a detection circuitry in the 8200A which takes precautionary measure and is shutting down/cutting off. So, can we rule out the overpowering possibility?

Good to know that there's a protection circuitry!

At moderate to low volume the Valhalla shouldn't overdrive the 8200. Has this been your observation? I vaguely recall you mentioning that the shutdown happens when you stop the music (it something like that). If so, we need to ask why is that event triggering the protection circuitry?

On a related note, most amplifier protection circuits are meant for protecting against the presence of large DC values in the output (this preserving the speakers), or shut it down if the negative and positive leads of the speaker cable are accidentally shorted (protects the amp from blowing up). We can rule out the latter. How about the former?

 

[hifitoaster]

Guys, thanks for the diagnoses and suggestions. Based on it all, I am currently hypothesising that the Valhalla 2 preamp (whose primary purpose is a headphone amp, but also has provisions to be used as a tube preamp) is not suited to be used with my SS Audiolab 8200A in power amp mode because Valhalla2 adds too much gain which the 8200A power amp is not able to handle causing it to frequently get into protection cut off.

So now, I think I have to start looking for a new preamp. I am quite clear that I want the tube sound - close to, or better than the current one. And my choices would be limited in terms of my budget. I need some suggestions on this, I have noted the Yaqin and Lyrita suggestions. But not sure how much they cost. Also, it’d be difficult for me to make the decision without trying how they sound in my system.

Schiit itself has a proper preamp now, the Freya, which has active tube, passive and JFET buffer stage options. The specs (attached below) show an output impedance of 210 ohms and gain of 5. Do you think, as per your analysis, this would match my Audiolab 8200A power amp section? What other factors I need to check to ascertain this compatibility? Would the problem I face with the Valhalla 2 be non-existent with the Freya? How can I ascertain this without an insystem trial (which I shall check with the authorised dealer if I can get - if they have demo piece and I can take my amp to check). I see the cost would be around Rs 70000, but I like the Schiit sound produced by the Bifrost DAC with the Valhalla 2 today, and imagine the Freya would be close to it, if not better (have to read the reviews in detail yet).

Another option for me is to replace both Valhalla 2 and the Audiolab with an integrated tube amplifier. Are there any good suggestions (sound and reliability wise) that come within Rs 100,000? Especially what I can audition in Mumbai. Please advise.

And, thanks!


View attachment 28820

Are there any Vincent dealers in India? I found one : http://www.focalaudio.in/vincent/txt_SV226.asp They sound incredible for the money.

 

[Deleted member 15865]

Good to know that there's a protection circuitry!

At moderate to low volume the Valhalla shouldn't overdrive the 8200. Has this been your observation? I vaguely recall you mentioning that the shutdown happens when you stop the music (it something like that). If so, we need to ask why is that event triggering the protection circuitry?

On a related note, most amplifier protection circuits are meant for protecting against the presence of large DC values in the output (this preserving the speakers), or shut it down if the negative and positive leads of the speaker cable are accidentally shorted (protects the amp from blowing up). We can rule out the latter. How about the former?

Thanks. The latter possibility (shorting of cables) is ruled out as this problem ONLY happens when the tube pre is directly connected with the 8200 power amp. Not if the pre amp of the 8200 is also in the chain, and also not if the tube is taken out and 8200 is run in integrated mode by itself.

The former (DC value in output of tube preamp) is a possibility that I need to get checked.

 

[jls001]

The former (DC value in output of tube preamp) is a possibility that I need to get checked.

DC checking is not tough (see earlier posts on how to). Buy yourself a multimeter for about Rs 500-600.

 

[Deleted member 15865]

DC checking is not tough (see earlier posts on how to). Buy yourself a multimeter for about Rs 500-600.

Thanks. I don’t mind spending the money. I only hope it’s safe for a noob (non-practising chemical engineer here, not electrical) to perform. Can you/someone help me with link to a reasonably priced but accurate enough (for this purpose) multimeter that I can purchase on Amazon?

 

[Deleted member 15865]

Ok I just recalled a similar experience with a friend putting a tube pre before SS.

Can you tell me which all those 4 tubes your pre is using ? I very much suspect that one of your tubes are Nasty and the power amp just goes into the protection mode Whereas the SS pre takes the hit.

The stock tubes only. This is the description from the specs page:

Tube Complement: 6N1P dual triode input, 6N6P dual triode output, 1 each per channel. 6N1Ps rollable to 6DJ8, E88CC, 6922, 6BZ7, and similar types.

 

[Kannan]

Mastech is quite good. i use model MAS830L

 

[Deleted member 15865]

Ok I just recalled a similar experience with a friend putting a tube pre before SS.

Can you tell me which all those 4 tubes your pre is using ? I very much suspect that one of your tubes are Nasty and the power amp just goes into the protection mode Whereas the SS pre takes the hit.

The stock tubes only. This is the description from the specs page:

Tube Complement: 6N1P dual triode input, 6N6P dual triode output, 1 each per channel. 6N1Ps rollable to 6DJ8, E88CC, 6922, 6BZ7, and similar types.

 

[jls001]

Can you/someone help me with link to a reasonably priced but accurate enough (for this purpose) multimeter that I can purchase on Amazon?

Visit Lamington Road.

Recently bought a Mastech MAS830 digital multimeter for Rs 550.

If you're anywhere near Andheri West, I know a place within 1 min walking distance from my place where to buy this particular model.

 

[Deleted member 15865]

Visit Lamington Road.

Recently bought a Mastech MAS830 digital multimeter for Rs 550.

If you're anywhere near Andheri West, I know a place within 1 min walking distance from my place where to buy this particular model.

Thanks. I’ve ordered a Fluke multimeter and shall be able to do the testing over the weekend.

 

[sound_cycle]

Valhalla2 feeding straight to 8200A power amp), the 8200A’s protection mechanism keeps cutting in. Now, this doesn’t happen immediately or with a predictable interval. It can sometimes happen almost once per twice a song, at other times I am able to play two or three CDs before this happens. But whenever this happens, the 8200A mutes itself for about 5-8 seconds and then comes on again playing the music further as if nothing happened.

I have a similar issue. While it might not be directly relevant it is possibly interesting.

i hooked up gungnir mb through saga to vidar. And Vidar was driven to protection mode at unpredictable intervals from instantly to about the duration of two tracks.

The probable causes 1) thermal overload 2) shorting in the speaker's/ cables 3) DC in the input to the amp.

It was 3). The gumby was faulty. If I had a multimeter I could have measured how much dc (correction if I had any brains, I have a multimeter). And it also took the woofers on the right channel out.

Gumby will be taken care of under warranty (sourced from the Indian distributor) but there is nothing to cover my speakers. I am hoping that saga and vidar are fine.

Ciao
GR

 

[sound_cycle]

The voltages on the RCA audio output would never do any harm..... Using a digital multimeter.

Sadly it can. And it need not be jigavolts. A few .Xx V of DC will do nicely to let magic smoke out

Ciao
Gr

 

[Deleted member 15865]

I have a similar issue. While it might not be directly relevant it is possibly interesting.

i hooked up gungnir mb through saga to vidar. And Vidar was driven to protection mode at unpredictable intervals from instantly to about the duration of two tracks.

The probable causes 1) thermal overload 2) shorting in the speaker's/ cables 3) DC in the input to the amp.

It was 3). The gumby was faulty. If I had a multimeter I could have measured how much dc (correction if I had any brains, I have a multimeter). And it also took the woofers on the right channel out.

Gumby will be taken care of under warranty (sourced from the Indian distributor) but there is nothing to cover my speakers. I am hoping that saga and vidar are fine.

Ciao
GR

Thank you so much. And sorry to hear about your loss. The symptoms of my problem are similar. Quite possible the problem is the same. Shall get it checked for DC offset. Did the Schiit distributor/service center accept the fault with the Gungnir?

Your experience suggests that I need to check both the preamp (Valhalla 2) and the DAC (Bifrost) checked for DC. Let me first try to isolate the DAC and see if the problem persists with the Valhalla 2 still in the chain. That will help me decide which one (DAC or Preamp) may be the cause.