Tube amp question or opinions

[Squishman]

For the longest time I have wanted to try a tube amp (even borrow one for a weekend if that was possible) to run my Klipsch Heritage speakers. I have heard that these speakers sound best with a tupe amp. Well I found one that was restored and for a decent price. But my question is this: If I got it and hooked it up to the front pre-outs on my RZ50, would that not defeat the purpose of using a tube amp (if a tube amp is actually better) since I would still have a SS connection in the chain? A couple years back TLS Guy said (in so many words) its not all it's cracked up to be. It is a legendary Dynaco ST70.

 

[PENG]

For the longest time I have wanted to try a tube amp (even borrow one for a weekend if that was possible) to run my Klipsch Heritage speakers. I have heard that these speakers sound best with a tupe amp. Well I found one that was restored and for a decent price. But my question is this: If I got it and hooked it up to the front pre-outs on my RZ50, would that not defeat the purpose of using a tube amp (if a tube amp is actually better) since I would still have a SS connection in the chain? A couple years back TLS Guy said (in so many words) its not all it's cracked up to be. It is a legendary Dynaco ST70.

I agreed with TLSGuy on his comments on tube amps, in general anyway. Whether yours will work as you anticipated depends on the specific model. Many tube amps, such as McIntosh's, were designed to be transparent, so those would likely sound just the same as their SS amps if the eyes are not involved.

Which tube amp do you have? You should look at the specs such as frequency response, distortions, input and output impedance. Those, as a whole, could answer you question. There is no mystery involved, amps amplify the input signal, it's all scientific, all measurable, hence predictable, without "hearing" them. The late Peter Walker (whom TLSGuy seems to respect) will tell you that, I think...

 

[Tankini]

There's these two, anyone wanting or needs a fix for Nostalgia, feeling of days gone by of gear with VU meter's. .ASR, site tested and gave his recommendation.

Gone are the days of following the Buffalo across the prairie.

 

[Squishman]

I will likely pass on the idea. A few reasons. What TLS Guy told me a couple years ago and connecting to SS defeats the purpose (I think). My La Scalas don't put out a tremendous amount of bass, So if I hooked it up independently, even temporarily, I'd probably not be satisfied without my sub. And also, I do not have a decent quality separate turntable preamp. Unless someone convinces otherwise, I will pass. Probably be hard-pressed to find a better one at this $$ though.

 

[cpp]

Regarding tubes, if you want tubes, get tubes, but be darn sure you chose wisely in matching your tube amp and to your speaker like PING noted. And then if you are adding a "pre-amp, make sure it compatible as well., And the world of tube rolling comes in, an expensive hobby in itself. IT can become a very slippery slope.

 

[TLS Guy]

For the longest time I have wanted to try a tube amp (even borrow one for a weekend if that was possible) to run my Klipsch Heritage speakers. I have heard that these speakers sound best with a tupe amp. Well I found one that was restored and for a decent price. But my question is this: If I got it and hooked it up to the front pre-outs on my RZ50, would that not defeat the purpose of using a tube amp (if a tube amp is actually better) since I would still have a SS connection in the chain? A couple years back TLS Guy said (in so many words) its not all it's cracked up to be. It is a legendary Dynaco ST70.

I restored an ST70 some years ago. It is bunk that they are superior to solid state amps, at least the amps I use. The problem with tube amps, is that there power is limited and clipping is clipping, whether is so called soft, or not as the enthusiasts call it. I can assure you it is far worse than NO clipping.

The issue that really is a major problem for tube amps, is that they cope poorly with impedance swings. This is a problem as decent passive speakers are baffle step compensated. All my speakers were. The issue is the output transformers, as they give tube amps a high source resistance relative to solid state amps. This makes their response upset by the speakers impedance curves. Baffle step compensation in a passive speaker pretty much always causes an impedance drop.

Much is made by tube enthusiasts of the fact that tube amps are all pretty much class A, and therefore don't have crossover distortion at low signal levels. However tube amps invariable have higher distortion at the higher ends of their output. However good solid state designs are biased class A at low outputs and transition to B. This is for reasons of reducing power consumption in the output devices. In a class A biased amp the power consumption and heating of the devices is constant however loud you play it.

I doubt that the low output level crossover distortion is audible in most designs.

I use unique amps that are called current dumpers by their designer the late Peter Walker. The output stages are heavily biased class B, and there is a very accurate class A amp that generates a feed forward error correction signal. It is a brilliant solution and even when pushing them hard they only get mildly warm and never hot. Since heat kills this contributes to the reliability of these amps. As you have heard they sound excellent.

A couple of words of warning about tube amps. NEVER have the amp on, not connected to the speakers. This destroys the output tubes fast and often makes them explode.

The other warning, is that amp is now old. Do you know if it has been restored? The voltages are high, and the aging high tension capacitors can explode without warning.

This happened to me when I was working on an old tube amp as a kid. The thing exploded violently and I was lucky I was not badly injured. It was a shock I will never forget.

Those ST 70s do have a protective cage, and for this reason.

Anyhow I sold the ST 70 after a year or two at a handsome profit.

 

[highfigh]

I restored an ST70 some years ago. It is bunk that they are superior to solid state amps, at least the amps I use. The problem with tube amps, is that there power is limited and clipping is clipping, whether is so called soft, or not as the enthusiasts call it. I can assure you it is far worse than NO clipping.

The issue that really is a major problem for tube amps, is that they cope poorly with impedance swings. This is a problem as decent passive speakers are baffle step compensated. All my speakers were. The issue is the output transformers, as they give tube amps a high source resistance relative to solid state amps. This makes their response upset by the speakers impedance curves. Baffle step compensation in a passive speaker pretty much always causes an impedance drop.

Much is made by tube enthusiasts of the fact that tube amps are all pretty much class A, and therefore don't have crossover distortion at low signal levels. However tube amps invariable have higher distortion at the higher ends of their output. However good solid state designs are biased class A at low outputs and transition to B. This is for reasons of reducing power consumption in the output devices. In a class A biased amp the power consumption and heating of the devices is constant however loud you play it.

I doubt that the low output level crossover distortion is audible in most designs.

I use unique amps that are called current dumpers by their designer the late Peter Walker. The output stages are heavily biased class B, and there is a very accurate class A amp that generates a feed forward error correction signal. It is a brilliant solution and even when pushing them hard they only get mildly warm and never hot. Since heat kills this contributes to the reliability of these amps. As you have heard they sound excellent.

A couple of words of warning about tube amps. NEVER have the amp on, not connected to the speakers. This destroys the output tubes fast and often makes them explode.

The other warning, is that amp is now old. Do you know if it has been restored? The voltages are high, and the aging high tension capacitors can explode without warning.

This happened to me when I was working on an old tube amp as a kid. The thing exploded violently and I was lucky I was not badly injured. It was a shock I will never forget.

Those ST 70s do have a protective cage, and for this reason.

Anyhow I sold the ST 70 after a year or two at a handsome profit.

I haven't seen "Much is made by tube enthusiasts of the fact that tube amps are all pretty much class A", but rather that they're biased fairly hot, they hate NFB and use tubes that have some mystique to them, like 2A3, 300B or KT-100/8550, looking down their noses at more common types like 6L6 or EL34/6CA7.

I had mentioned the 200W/channel Conrad Johnson Premier One that I heard when the Infinity IRS speakers were being demo'd at CES- the key to any tube amp sounding clean is having enough power that it's never necessary to use it. Avoiding the point of clipping isn't difficult when the speakers are designed or chosen intelligently. Klipsch speakers were very sensitive because he was designing them when tube amps were common- he was quoted as saying something similar to "With a 5W amp and a pair of my speakers, what more could you need?"- oh, I guess speakers that can pass full bandwidth would be a good start- some were able to produce the FM audio bandwidth ±3dB, but that was all. I replaced the tweeter diaphragms in a pair of 1970s Heresy and the RTA showed that response- I thought something was wrong until I searched for the specs and found that they matched.

IMO, it's important to use source material that matches the music of the time- I played several selections and the Hereseys didn't sound good until I played some Jazz with acoustic instruments and some Classical- with that music, they sounded really good and it was the first time I heard a pair of those and liked the sound.

As an exercise, I think it would be interesting to find a tube amp that can produce wide band response without distortion but for everyday use, it's good to be able to turn a system on and off when it's needed, rather than fearing damage to the tubes from frequent ON/OFF cycles.

WRT not being connected to speakers- I might worry more about the output transformer(s)- shorting the output is a great way to turn tubes into light bulbs.

Caps popping is a special experience, especially when it's unexpected. Hot, flying glass is never a good thing.

 

[MrBoat]

I have found that many who are looking into tubes these days are not as happy with their speakers as they had hoped. It's almost always those with either the flattest measuring speakers trying to play mainstream pop/rock thru them, or the brightest of horn speakers. Especially now that the inclusion of tone controls/EQ are fewer and farther between, and with modern interior decor being so open and reflective now, compared to when tubes were popular.

We had tube stereo in our home in the '60s, but we also had heavy sculpted wall-to-wall carpet with 'rubber' waffled padding, heavy curtains, less windows, sectional floor plans and enough enough cozy furniture for a family of 7 in a 1500 SQ ft. house. Now, half the family/double sq. footage is more the norm, with much less in the way of cozy.

I always tell them to try EQ first and knock a db or two off the 4khz and up range. Especially speakers that tend to have even the slightest rise in the FR there, which so many seem to now. Whether by design, or accident, my favorite speakers always tended to slope slightly downward in that range and almost never had issue with brightness or lack of warmth, and the further away from clipping, the better.

As stubborn as I am with regard to being passionate about antique furniture and technology, too many years have passed. I had already gotten a double life out of my oldest solid state gear, and even it, is too old for me to take seriously now. It ends up sitting (albeit restored and functional) as museum pieces.

 

[highfigh]

I have found that many who are looking into tubes these days are not as happy with their speakers as they had hoped. It's almost always those with either the flattest measuring speakers trying to play mainstream pop/rock thru them, or the brightest of horn speakers. Especially now that the inclusion of tone controls/EQ are fewer and farther between, and with modern interior decor being so open and reflective now, compared to when tubes were popular.

We had tube stereo in our home in the '60s, but we also had heavy sculpted wall-to-wall carpet with 'rubber' waffled padding, heavy curtains, less windows, sectional floor plans and enough enough cozy furniture for a family of 7 in a 1500 SQ ft. house. Now, half the family/double sq. footage is more the norm, with much less in the way of cozy.

I always tell them to try EQ first and knock a db or two off the 4khz and up range. Especially speakers that tend to have even the slightest rise in the FR there, which so many seem to now. Whether by design, or accident, my favorite speakers always tended to slope slightly downward in that range and almost never had issue with brightness or lack of warmth, and the further away from clipping, the better.

As stubborn as I am with regard to being passionate about antique furniture and technology, too many years have passed. I had already gotten a double life out of my oldest solid state gear, and even it, is too old for me to take seriously now. It ends up sitting (albeit restored and functional) as museum pieces.

Solid state amplifiers don't have a big problem with most speaker loads, but tube amps can. It's the lack of understanding about how speaker impedance affects tube amp output that makes them dislike their speakers.

What old SS gear do you have? If it's acting up, clean the controls and switches- they oxidize and lose contact if they aren't moved and most controls & switches are never adjusted or moved, which causes the signal to stop. I can't estimate the number of people who brought their stereo equipment into the store where I worked, for service. Many thought their receiver launched either/both channels and in most cases, it just had dirty controls and/or switches.

 

[Squishman]

I restored an ST70 some years ago. It is bunk that they are superior to solid state amps, at least the amps I use. The problem with tube amps, is that there power is limited and clipping is clipping, whether is so called soft, or not as the enthusiasts call it. I can assure you it is far worse than NO clipping.

The issue that really is a major problem for tube amps, is that they cope poorly with impedance swings. This is a problem as decent passive speakers are baffle step compensated. All my speakers were. The issue is the output transformers, as they give tube amps a high source resistance relative to solid state amps. This makes their response upset by the speakers impedance curves. Baffle step compensation in a passive speaker pretty much always causes an impedance drop.

Much is made by tube enthusiasts of the fact that tube amps are all pretty much class A, and therefore don't have crossover distortion at low signal levels. However tube amps invariable have higher distortion at the higher ends of their output. However good solid state designs are biased class A at low outputs and transition to B. This is for reasons of reducing power consumption in the output devices. In a class A biased amp the power consumption and heating of the devices is constant however loud you play it.

I doubt that the low output level crossover distortion is audible in most designs.

I use unique amps that are called current dumpers by their designer the late Peter Walker. The output stages are heavily biased class B, and there is a very accurate class A amp that generates a feed forward error correction signal. It is a brilliant solution and even when pushing them hard they only get mildly warm and never hot. Since heat kills this contributes to the reliability of these amps. As you have heard they sound excellent.

A couple of words of warning about tube amps. NEVER have the amp on, not connected to the speakers. This destroys the output tubes fast and often makes them explode.

The other warning, is that amp is now old. Do you know if it has been restored? The voltages are high, and the aging high tension capacitors can explode without warning.

This happened to me when I was working on an old tube amp as a kid. The thing exploded violently and I was lucky I was not badly injured. It was a shock I will never forget.

Those ST 70s do have a protective cage, and for this reason.

Anyhow I sold the ST 70 after a year or two at a handsome profit.

Wow, good warnings! Here is the link to the unit. It has been restored. I think the price is right. If someone is interested, get it! I am no longer interested as much as I thought I was. https://www.facebook.com/marketplace/item/742181750843348/?ref=search&referral_code=null&referral_story_type=post&tracking=browse_serp:6b2c2af1-aa9f-4355-ade1-c0e65019168a

 

[Squishman]

Solid state amplifiers don't have a big problem with most speaker loads, but tube amps can. It's the lack of understanding about how speaker impedance affects tube amp output that makes them dislike their speakers.

What old SS gear do you have? If it's acting up, clean the controls and switches- they oxidize and lose contact if they aren't moved and most controls & switches are never adjusted or moved, which causes the signal to stop. I can't estimate the number of people who brought their stereo equipment into the store where I worked, for service. Many thought their receiver launched either/both channels and in most cases, it just had dirty controls and/or switches.

I have newer ss amps. Denon AVR, Onkyo AVR, plus a Yamaha stereo rcvr 15 or thereabout years old and a Pioneer stereo rcvr for my computer that is probably 7 years old. It has a subwoofer output so that's a bonus. Four sound systems in this mobile home! ha.

 

[highfigh]

Wow, good warnings! Here is the link to the unit. It has been restored. I think the price is right. If someone is interested, get it! I am no longer interested as much as I thought I was. https://www.facebook.com/marketplace/item/742181750843348/?ref=search&referral_code=null&referral_story_type=post&tracking=browse_serp:6b2c2af1-aa9f-4355-ade1-c0e65019168a

The duct tape over the 16 Ohm terminals is a nice touch.

That has a lot of newer resistors- if it was just caps and tubes, it might be interesting but that's a lot of money to pay for someones' service that may or may not be great. Not sure what the plexi over the circuit board adds, but OK. Kind of wondering why the small tubes weren't fully inserted, either.

This has replacement tubes, too. The originals were great, the output tubes look like recent issue and while they may be good, I have read about issues. The silicone rubber bands don't help with anything- if a tube is microphonic, it should be rejected unless it happens at high SPL than the system is EVER operated.

The small 12AU7 tubes are easy to find, even the vintage ones but a vintage 5AR4/GZ34 rectifier or a set of four EL34 output tubes are very expensive- a new set of El34 will run about $169 at the minimum and can be closer to $500 but the asking price on Ebay for a set of four good vintage tubes can cost well over $1000. I have found this rectifier (the single tube that's not as large as the output tubes) for more than $50, so a set like this, assuming the small tubes were less than $10 each, will run at least $250. That means the amp with its replaced parts is worth about $550 and there's no guarantee that it will work at all, never mind the long term.

If you decide to get into a tube amp, I would recommend being patient.

 

[highfigh]

In my search for tubes that apply to this amp, I have realized that I need to sell most of mine somewhere other than Ebay.

 

[Squishman]

There is a lot of stuff to know to add tubes to a hifi hobby. Better to stay well enough away. For me anyway! I'd probably have to shop for a tube pre-amp then too.

 

[ski2xblack]

Tube amp for mains only?

Happy new year! I have Klipsch Forte II's for my mains in my 5.1.2 HT powered by a Yamaha RX-A1060. I have often wanted to hear my Forte II's powered by a tube amp for 2 channel listening (mainly LP's). Or 2.1, actually. But if I found a tube amp and plugged it into the pre-amp outs, would I not...

forums.audioholics.com

I thought this seemed familiar. You still have the tube bug pretty bad, it seems. "Buy and try" is the last thing you need to do. DIY is cheaper and more edifying, but you'll learn what we've been telling you all along.

 

[Squishman]

Actually less now. Seeing this for sale piqued my interest again. This unit is about 4 miles from me and it was restored and the price was not too shabby. I'll never see that all at once again. I recall when TLS Guy told me its not all its cracked up to be, I was happy to hear that, so now it was good to put the kibash on that idea probably permanently

 

[TLS Guy]

Actually less now. Seeing this for sale piqued my interest again. This unit is about 4 miles from me and it was restored and the price was not too shabby. I'll never see that all at once again. I recall when TLS Guy told me its not all its cracked up to be, I was happy to hear that, so now it was good to put the kibash on that idea probably permanently

That Dynaco is not original. The PC board is new and different. A tube has been added which must be a dual tube shared between channels. This is probably not a good idea and likely to lead to some crosstalk.

A lot of these units have been modified. Only about 5% of these units are factory. 95% were bought as kits and built by the original owners.

 

[TLS Guy]

Actually less now. Seeing this for sale piqued my interest again. This unit is about 4 miles from me and it was restored and the price was not too shabby. I'll never see that all at once again. I recall when TLS Guy told me its not all its cracked up to be, I was happy to hear that, so now it was good to put the kibash on that idea probably permanently

If you are going to get into vintage tubes you need to know what you are doing. You have to have an electronic workshop of some type, as the grid bias needs tweaking relatively frequently, at least that was my experience of that Dynaco amp.

 

[Squishman]

If you are going to get into vintage tubes you need to know what you are doing. You have to have an electronic workshop of some type, as the grid bias needs tweaking relatively frequently, at least that was my experience of that Dynaco amp.

It's all above my pay grade. I'm done! And happy about it.

 

[MrBoat]

Solid state amplifiers don't have a big problem with most speaker loads, but tube amps can. It's the lack of understanding about how speaker impedance affects tube amp output that makes them dislike their speakers.

What old SS gear do you have? If it's acting up, clean the controls and switches- they oxidize and lose contact if they aren't moved and most controls & switches are never adjusted or moved, which causes the signal to stop. I can't estimate the number of people who brought their stereo equipment into the store where I worked, for service. Many thought their receiver launched either/both channels and in most cases, it just had dirty controls and/or switches.

My old stuff has been restored and works fine and I still use it occasionally. I have an Adcom GFA-5500 and and my first Pioneer amp which is an SA-8500 among others. But I won't be rebuilding them again or adding to the collection. If they had bass management, I'd still be using them full time.

But still, it's just so much easier and more efficient with class D stuff, or even the A/B stuff from the last couple decades and without those dreadful analog pots. It's been all about the speakers (provided the amps are capable) for me for the last 30 years or so anyway.

I have some other MOSFET amps from 8-25 watts that I amuse myself with occasionally, but this class D stuff is getting too good to ignore.