To @wolf_garcia, which output tubes did you land on for your DH Firebottle HO amp?
Your journey with lower-watt tube amps -- Can a kit be good enough?
Looking for stories about your low-watt amp journeys.
Here's the situation: I have new speakers, 97 db. Trying them with lower watt tube amps (45/211, 300b, etc) seems generally wise. I am attempting to borrow some from audiophiles in the area.
The horizon beyond trying these things involves actually buying some. I'm looking at a budget limit of about $5k.
Curious as to folks' experience with lower-watt amp kits vs. those of good makers (e.g. Dennis Had, etc.).
If you have any thoughts about the following, I'd be interested:
Did you start out with a kit and then get dissatisfied? Why?
Did you compare kits vs. pre-made and find big differences?
Did you find you could get the equivalent level of quality in a kit for much less than the same pre-made version? How about kit vs. used?
Also: did you find there was a difference between "point to point wiring" vs. "PCB" in these various permutations?
I realize that there are good kits and bad ones, good pre-made amps and bad ones. I'm hoping you'll be comparing units which seem at comparable levels of quality and price-points.
Thanks.
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I'm currently using Gold Lion KT66s, a NOS Amperex 6SN7GTB (looks like a re-branded GE), and a "Tubestore Preferred Series" 274B rectifier. Note I have a drawer full of tubes including more GLs (88s, 77s, 90s, 120s, etc.) and other stuff. The 66s are pretty great, but I'll likely get bored and swap em out at some point...for now they stay. |
@alexberger Here's what my tech friend and amp builder said about your comment, in case you're interested: "It doesn't [have an interstage transformer], but then again most single-ended amps don't have an interstage transformer, nor most PP amps for that matter, they are expensive. The 845 is hard to drive and since the SV uses a 12BH7 to drive it, there is less power than if driven with a larger tube or an interstage transformer. Clearly it is not "impossible" as the amplifier operates." |
I don't want to interpret for someone else, particularly someone with vastly more hands on equipment building and technical knowledge than Alex Berger, but, I don't think "impossible" meant it cannot be done--its more like it cannot be done optimally. Clearly Sun Valley is doing it; the question is whether this is a good approach. I think that there are lots of suboptimal designs that are done to lower cost, so it is helpful that Alex Berger is pointing this out. I too have my doubts about the plethora of low cost 300B SET amps with 12AX7 drivers and no interstage transformer--this might be less than ideal, so the question is whether this is the right cost-quality tradeoff. I am not saying it is the wrong tradeoff, but, it helps for buyers to be aware of the issue. |
@alexberger This statement is entirely false (and is what IT manufacturers would like you to believe). If the driver is a cathode follower and direct-coupled to the grid of the power tube you'll have no problem with drive and less distortion than you can get with an interstage transformer. SET designers don't do it because you have to have a B minus supply for the driver tube and they don't want to spend the money although a good interstage driver transformer will cost more. The other reason SETs designers don't do it is they didn't think of it! You'll recall I mentioned this technique on another thread on which you were active on this website. For the record we've been driving power triodes in exactly this manner for decades (47 years to be more exact). The driver has an iron grip on the grid of the power tube and can easily drive it into grid current with good linearity. It also prevents blocking distortion which is a problem for any tube amp which employs coupling capacitors between the driver and grid of the power tube so you get instantaneous overload recovery. You might try it since you're into DIY. If you have any questions about how to go about it, email me. |
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