New to AK, looking for my first tube amp.

bberkom

bberkom

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I just recently joined Audiokarma on rec from a friend after convincing myself I need a tube amp for my system. I've subscribed so that I can access the bartertown forum, but I need some basic advice. I have been collecting records for a long time, but I think it's time for me to go tube. I have a 2.1 system with Polk tsi400 speakers, and polk sub, a project debut III table with some upgrades, and it's all running through a harmon kardon HK 3490 stereo receiver.

This receiver has plenty of power for these speakers, rated at 120 wpc, but I don't think they are super efficient speakers. I'd like to replace it with an integrated tube amp, but I am not sure how much tube-power I should be looking for. After some initial research it seems like 20 wpc may be sufficient? I also may just need to get more efficient speakers to run a tube amp, but I'd rather not have to do both speakers and amp. But I need some help!
 
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I run Klipsch KG4s with my Scott 299B at 20 wpc and Fisher X-200 at 35 wpc. Love the sound of tubes and horns! Dave
 
Looks like they're 91dB sensitivity, so not too bad. Tube watts can get expensive.

What's your room size and how loud do you like to go?
 
I'm curious about this too, though I don't think I'm quite ready to take the plunge yet. Among the stuff I've read recently are conflicting opinions regarding a hybrid amp by Jolida, model JD301BRC, which (if I understand correctly) combines a tube-based pre-amp with a MOSFET transistor power amp. A reviewer at CNet digs this with Wharfdale Diamond speakers as an outstanding entry-level system; other commentators seem to think he's demented.
 
Unless you have huge room and/or like things really loud, 20WPC should be fine, but if you want more you could consider a Dynaco ST70 (35 per channel). Mine is running at the moment. Think of the volume pot as a clock face, starting at 6. My tube preamp is currently at between 7 and 8 for comfortable listening. If I turn it to 9 it'll disturb people at the other end of the house. If I go to 11, it'll bother the neighbours. That's with KEF 104/2 speakers (92dB).

richardgrant, a hybrid won't give you the full tube sound.
 
captouch said:
Looks like they're 91dB sensitivity, so not too bad. Tube watts can get expensive.

What's your room size and how loud do you like to go?
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My room is about 25'x25' open living space with hardwood floors, lots of furniture. I don't usually listen too loud, and I'm usually not trying to push sound to other parts of my house. That room is probably 50% of my whole house anyways.
 
Dandy said:
Unless you have huge room and/or like things really loud, 20WPC should be fine, but if you want more you could consider a Dynaco ST70 (35 per channel). Mine is running at the moment. Think of the volume pot as a clock face, starting at 6. My tube preamp is currently at between 7 and 8 for comfortable listening. If I turn it to 9 it'll disturb people at the other end of the house. If I go to 11, it'll bother the neighbours. That's with KEF 104/2 speakers (92dB).

richardgrant, a hybrid won't give you the full tube sound.
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I have heard and read good things about the Dynacos. It seems they are going to start remaking this model too. It seems like it could be a great first tube amp.
 
I saw your WTB ad. I think the ST-70 is an excellent choice to get you started. I have one, upgraded with a VTA driver board. I've only compared it directly against a couple of high power SS amps, but it beat both in sound quality pretty handily.

Lots of info and upgrades available for this model. Good luck on finding a nice one.
 
captouch said:
I saw your WTB ad. I think the ST-70 is an excellent choice to get you started. I have one, upgraded with a VTA driver board. I've only compared it directly against a couple of high power SS amps, but it beat both in sound quality pretty handily.

Lots of info and upgrades available for this model. Good luck on finding a nice one.
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Yeah I'm starting to see how expensive tube power can be now that I've spent some time looking into it. I've realized I'll also need a preamp for my system if I choose to go this way, so I'm wondering if an integrated amp may be a better fit or even more cost effective?
 
There is also the issue of sensitivity vs power. Talking just about amplifiers, many are quite sensitive and can be driven by passive preamps (or linestage) - source from CDs is sufficient, and if you have a phono pre that also should be sufficient. The consideration here is that if your preamp amplifies an already sufficient signal, then your volume pot (actually attenuator) can only be turned up a bit to achieve the listening volumes you want. On an integrated I was using max volume was at 9 o'clock on the volume pot. Basically you are amplifying the signal only to attenuate it before it hits the power amp. Some consider the preamp signal 'conditioning' useful, some consider it distorting. The amplification makes it hard to get the volume where you want because of so little range on the knob to play with. Potentially the same issue on an integrated. The power is more important, I think. Lower power seems to drive the mid and high speaker drivers well, but getting the big bass iron moving well takes more juice. I am thinking about comfortable listening levels. I went from a 30 wpc tube to a 50 wpc tube and the bass really bloomed. Could have been the amp design, but no other components in the system changed. My simplistic sense of it is that there is plenty of 'headroom' on the 50 wpc amp, so when the bass driver demands juice, then the amp can deliver. I am guessing that the 30 wpc just could not deliver. If you are looking at a single 8" woofer then maybe no problem. If you are thinking of 12 inch or 15 inch woofers, that is big thirsty iron. They can sound great, but only if you give them what they need....

regards -- Roger
 
bberkom said:
Yeah I'm starting to see how expensive tube power can be now that I've spent some time looking into it. I've realized I'll also need a preamp for my system if I choose to go this way, so I'm wondering if an integrated amp may be a better fit or even more cost effective?
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It'll likely be more cost effective in the short term, but there's a lot of factors to consider, such as whether you think you'll be satisfied with an integrated long term, or that you'll want to go with separates eventually.

Also, would you want to go full tube, or are you okay with a hybrid integrated - most hybrids would use a tube pre and SS amp?

And then, whether you have a preference for vintage or modern. Some of that might depend on whether you're comfortable working on vintage gear or not.

Any idea which way you're leaning on above?
 
captouch said:
It'll likely be more cost effective in the short term, but there's a lot of factors to consider, such as whether you think you'll be satisfied with an integrated long term, or that you'll want to go with separates eventually.

Also, would you want to go full tube, or are you okay with a hybrid integrated - most hybrids would use a tube pre and SS amp?

And then, whether you have a preference for vintage or modern. Some of that might depend on whether you're comfortable working on vintage gear or not.

Any idea which way you're leaning on above?
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Great points. I am trying to pick a cost-effective starting point and leave myself some flexibility if I decide I really want to juice up my system and go full tube. I don't think I want a hybrid, though. If I go with separate pieces, that will leave me more flexibility but will probably be more of an initial commitment. So I may grab an integrated just to get my feet wet. The Fisher X-100-B that I am looking at, if I can get it, would probably be around $300-$350 and is in pretty good shape.
 
rogerh113 said:
There is also the issue of sensitivity vs power. Talking just about amplifiers, many are quite sensitive and can be driven by passive preamps (or linestage) - source from CDs is sufficient, and if you have a...

regards -- Roger
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Thanks for the info. I'm quickly finding out how complicated this stuff is! That's kindof why I started leaning towards an integrated as my first tube amp. I am sure once I start down the road, though, that I'll quickly feel the need to upgrade...
 
In inegrated bring a level of complexity...because its got a preamp in it. An ST-70 is the way to go for a my first tube amp. Simple, flexible an a solid good sounding piece, lots of things you can do to it, and can be had for cheep. Its everything you want without the complexity of a preamp.

What you can do and this leave you well set up for the future is get an ST70, do it up and use your HK as the preamp. Its got a preout signal, you can use that as your preamp. I did it for years with a pioneer solid state that has preouts, fed that to my st70. That way when you got a better idea of where you wanna go, youve got a solid amp and you go do what ever you want. Everyone will say you wont get the full effect yeah yeah yeah, but you need your foot in the door, and this is the best way i think to suit your kneeds, and its still gonna make a helluva difference on the sound
 
coffee123 said:
In inegrated bring a level of complexity...because its got a preamp in it. An ST-70 is the way to go for a my first tube amp. Simple, flexible an a solid good sounding piece, lots of things you can do to it, and can be had for cheep. Its everything you want without the complexity of a preamp.

What you can do and this leave you well set up for the future is get an ST70, do it up and use your HK as the preamp. Its got a preout signal, you can use that as your preamp. I did it for years with a pioneer solid state that has preouts, fed that to my st70. That way when you got a better idea of where you wanna go, youve got a solid amp and you go do what ever you want. Everyone will say you wont get the full effect yeah yeah yeah, but you need your foot in the door, and this is the best way i think to suit your kneeds, and its still gonna make a helluva difference on the sound
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Man I think that's a great point. I was considering a Fisher 500c that someone has had mostly restored, at least the parts I wouldn't be comfortable with. Now I'm all undecided about going integrated versus separate and just doing the preamp later.
 
rogerh113 said:
If you are thinking of 12 inch or 15 inch woofers, that is big thirsty iron. They can sound great, but only if you give them what they need....
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I don't think it works this way. Many consoles have 12 or 15 inch woofers with quite modest amps. It depends on the sensitivity of the drivers.

I tend to agree with those who say get a Dynaco ST70 to start with, and use a SS amp as a preamp. It's also easier to understand tubes if you just start with a power amp. Those integrateds can be a bit scary for beginners.
 
Dandy said:
I tend to agree with those who say get a Dynaco ST70 to start with, and use a SS amp as a preamp. It's also easier to understand tubes if you just start with a power amp. Those integrateds can be a bit scary for beginners.
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I agree as well. Many hardcore audio folk will eventually move toward separates, and it really allows you to have a lot of choices in sound by using different preamps.

I'm kind of going through that now - trying to decide which preamp(s) to settle with long term. I'll likely narrow it down to two, but I don't feel a need to change the amp as a redone ST-70 seems to meet my threshold for quality sound without feeling the need to upgrade the amp side of things.
 
The thing about the ST70 is that the output transformers are excellent and this is what matters. Apart from upgrades to the boards, there are further things that can be done later, e.g. upgrade the power supply, use different tubes, etc. All this when the stock design sounds great.
 
After doing my old Maggie Imperial (15" woofers btw with a 6v6 biamp sterero amp 15ish watts to the woofers) I went on the same hunt, I wanted a Stereo tube amp and ended up with the ST70. I got with it a PAS3 and an FM3, so I have a whole set, complete with telefunken tubes in the preamp and the FM tuner. The AMP however was poorly and horribly modified, (someone made it mono, replaced the original power transformer with 2, added 2 huge electrolytic caps and a solid state diode rectifier) but had the original audio tranformers and RCA fat bottle EL34's, so it was a good platform to start with. I needed a driver board so I went with the VTA board new JJ tubes for the board and the rectifier, and a new power transformer, choke and all that jazz. I couldnt be happier. There is so much info out there for the amp, diagrams, schematics etc etc you cant go wrong. Support for it is amazing an its just a good solid good looking/sounding piece of gear, its on right now as I type this makin my Wharfdale W30d's sing.

Here is a before and after pic to give you an idea. I was worried about being on over my head, especially cause it was so bad when I got it, I stripped it completely to the chassis, no wires, nothing. Im good with electrical, but im not an electronics guy. I learned a lot about how it really works with this one, and you can see how well it came out. I did polish the nickel chassis a bit, and painted the audio transformers. You can see part of a beer can holding that one cap on from the before pic haha. I do have the cage for it too.



 
http://www.tubes4hifi.com/home.html

Check out the ST-70 kit. It's fun and a fantastic sounding tube amplifier. You can still use your HK preamp out as a pre. The 70 doesn't seem to mind using SS preamps. I've tried and they sound fine. This is better than buying a real vintage one and restoring it.

Or Option two. Go over to the vintage forum at Audioasylum and ask about the smaller tube integrated amps. Like a Eico, Scott or Sherwood, etc... would run you about $550 and about $550 in restoration and you're set for life. Don't under estimate those small stereos!
 
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