Never Owned a Tube Amp and Want Advice

@dsper Ask him if he can wire the woofers in series rather than parallel. It will require a little bit of adjustment in the crossover but otherwise the math of the drivers in the box is exactly the same. Contrary to popular myth, the woofers will be no less easy to 'control'. But it will make the speaker much more friendly to tube amps and all amps will have lower distortion driving a load like that.

^^Good- that's how its supposed to work :)

The Audio Technica cartridge could be part of my problem as I was not knowledgeable about tone arm and cartridge compatibility. I would have to admit the AT cartridge is a bad match for the light weight Technics tone arm. Anyone interested in a AT150MLX cartridge?

The stylus often suffers in older cartridges- the suspension in the cantilever can perish whether the cartridge is used or not. At that point it will sound tipped up in the treble and harsher/more sibilant than it should. If the cartridge is also a poor match for the arm that certainly isn't helping things! I use an older SL1200 in the recording studio to play back cuts we have made on the LP mastering setup. I use a Grado Gold in that arm and it seems to work quite well with it- tracks well, smooth and detailed.

In the meantime, I set up my turntable.This is a Technics SL1200Mk 5 with an AT150MLX cartridge.

Turntables, especially those with high output, can have a variety of issues causing sibilance. Make sure you have a low capacitance cable between the tonearm and preamp- that will help prevent brightness. The cable should not be more than a meter and 12-20pf per foot is a good value for capacitance of the cable.


The mechanical setup of the cartridge in the arm (VTA, tracking angle and the like) also can affect its tonality. The platter pad can too- the rubber mat found on most Technics machines isn’t helpful. This is all probably a topic for another thread, but since it all affects sibilance I felt I should mention this.

My tube rolling experience with preamps tells me that you can get these types of effect from different tubes. Does the same thing hold true for tube amp 6922 driver tubes?  

Currently, there are Electro Harmonix tubes in the two driver positions and a Sovtek Reflector in the input/phase splitter position. I know I do not like Electro Harmonix in my CJ preamp.

Wonder would happen if I changed out the Electro Harmonix tubes?

You've just put your finger on exactly the problem with using 6922/6DJ8s in amplifiers. Its hard to find a good one! The tube is very prone to microphonics and harsh sound. The Russian tubes IMO made this problem even worse.


Yes, if you have decent tubes the sound of the amp will change quite a lot. I've personally had terrible luck with the EH 6922. IMO, its pretty easy to find better sounding tubes than any of the Russian-made miniature tubes- 12AX7, 12AU7, 6922 and so on. Its not surprising at all to hear that a microphonic 6922 is causing silibance!!

I need to hook up the turntable and have not done that yet.

Do that and try something with vocals.

To be clear, I am talking about "bliss" and "sound" versus "blisss" and "ssound".

I get it. Do you have another source besides CD? If no this could be a digital problem... is it in both channels??

Regarding the sibilance- that really shouldn't be showing up at all, even on a new speaker (it might be bright until it breaks in, but sibilance suggests something wrong).


Does it do this on all sources?

Thought it would be a fairly low cost way to see if I can hear a tube difference

The difference between tube and transistor is usually pretty easy to hear. I've had people walk in from off the street and they were able to tell the difference. I wouldn't worry about that!

might be true for ralph's amps but this is something that is best NEVER to do

Yes!- in case it wasn't clear, don't pull power tubes out of any amp that has an output transformer while its running.

Don't run your new tube amp without a load attached as it can destroy the unit.

If the amp is of competent design, *as long as there is no signal at the input* this should be no worries. Our amps do not care about the input and output condition- they are unconditionally stable- you can even pull power tubes out while its playing and the amp acts as if nothing happened.

To be perfectly clear, energy stored in the supply is how an amp can handle an orchestral crescendo that would cause it to exceed its continuous power rating, correct?

No. The extra energy is useful to reduce IMD at higher power levels. Essentially it allows the power supply to have less noise- and less noise in the power supply results in the lower IMD of the amp.

Since this is a conversation about having enough power, what about going for a larger tube amp like 100 wpc.

As you increase the power of most tube amps, the output transformer has to be able to handle that power and at the same time make bandwidth. The problem is this basically doesn't happen; with output transformers as you build progressively larger devices, bandwidth is increasingly more difficult to obtain. For decades, 60 watts was the 'sweet spot' for push-pull tube amps, where they could make the power and still have the bandwidth needed (5-100KHz). You may not think that bandwidth above 20KHz is important, but unless you have a great degree of feedback (above 35dB or so) that bandwidth is important to prevent phase shift which can cause issues with tonality and the soundstage presentation.


Another thing to think about is the simple fact that 100 watts is not a great deal of power over 60 watts insofar as the ear is concerned- its slightly less than 3dB which is barely louder to the ear. But a 100 watt amp might have other properties (assuming bandwidth isn't an issue) at lower power levels that could be in its favor. So its a mixed bag.

OTLs get around the bandwidth issue by getting rid of the output transformer, so that tradeoff does not exist in them when going to higher power levels- a 200 watt OTL can be as fast, dynamic and transparent as a smaller one.

When I think of solid state, I understand that the continuous power rating is one thing and peak power supply is another.

My question is:

Is it true with tube amps that if an amp is rated at 60 wpc that is all you are going to get or do capacitors, power transformer, etc. come into play to allow higher peak power?

Peak power is an early 1970s thing. All amplifiers today are rated at continuous power. 

Now 'peak power supply' as you put it might be a current rating that has to do with what happens when you short out the power supply, and might be stated in amps. This is really a statement of how much energy is stored in the supply (and how big the spark will be when you short it out) rather than anything to do with how much power the amp makes.

Most tube amps are "optimistically" rated. That 60 watt tube amp might deliver that wattage at peak, but at 60 watts, it would be typically distorting quite a bit. Tube amps simply do not do well in a numbers game.  

This has nothing to do with tube or solid state and has everything to do with how conservative the manufacturer is with their ratings. We rate our amplifiers for RMS power into an 8 ohm load and we rate them to not be clipping at that power level. Now there are different definitions used by several measuring organizations such as Stereophile, but clipping technically speaking is when you see the test sine wave signal getting a flattened top and bottom- as if someone 'clipped' the top and bottom of the waveform off with a pair of scissors. That is why its called 'clipping'. Any other definition is arbitrary.

  For my taste, they are a touch lean (midrange on up being a bit more prominent than upper bass), but that is a matter of taste, and the good attributes of Atmasphere amps can be quite compelling.

Being more load sensitive, this has far more to do with how the amplifier is dealing with the load rather than the actual character of the amp itself. If you have it on a proper load (and the Tyler appears to be an excellent example) its not at all lean. The bigger the OTL, the less of an issue this is, IOW smaller OTLs are more load sensitive.


Now @larryi made a  good comment about amplifier clipping- if you plan to use a solid state amp, my surmise is you'll need to have about 200 watts to do what a 50-60 watt tube amp will seem to do on this speaker, entirely because of the simple fact that tube amplifiers clip (overload) so much more gracefully than solid state. When a solid state amp breaks up, its instantly audible even if its only for a few milliseconds. But in the case of a tube amp this isn't always true. They can overload so gracefully that it may not be apparent until the amp is really heavily overloaded. IME its important that the amplifier have instantaneous overload recovery- this is very helpful in minimizing the audible artifacts when the amp is briefly overloaded. This is why tube amplifier power seems to carry more weight than solid state.

The decibel reading at my chair is averaging 80 dbl with peaks at 92 dbl.

@dsper

50 watts should be enough unless your room is really big.

Can it cover the low frequency impedance dips.

Our amps are some of the most sensitive of amps to load, and even they would be fine on a speaker like this. You’ve no worries about a dip 6 ohms with any tube amp made!

The speakers in question are Tyler Acoustics. Tyler advised me they are 8 ohm 88 dbl and should not dip below 6 ohms.

@
In terms of impedance this speaker is an easy load (which is good regardless of what kind of amp you have, but with tubes this is particularly helpful). The only issue is whether 50-60 watts is enough power. What are you playing them with now?