Hello All, I am looking for your (forum's) advice on a project I want to try; Eli Dutmtman said in one of his posts "An elegant full function tube preamp mated to 1st rate SS power amplification..."
This is what I am looking for, an elegant tube preamp KIT to work with my Hafler DH500 power amp. FYI - I have gone through the Hafler (which I built from kit) and upgraded the few (in my opinion) short-comings of it, the internal signal wiring has been replaced with Kimber wire, the input and output jacks have been replaced w/WTB connectors, and that's it. currently, it works great, it doesn't sound great, as it has no sound. it's silent (no hum).
Anyway, I would like to build a Tube preamp, as my understanding, this is where the most significant "changes" can be realized. I have a foot in both worlds, I love my REGA turntable spinning vinyl, and I will also play CD/SACD's.
Your suggestions and help is appreciated. Thank you.
This is what I am looking for, an elegant tube preamp KIT to work with my Hafler DH500 power amp. FYI - I have gone through the Hafler (which I built from kit) and upgraded the few (in my opinion) short-comings of it, the internal signal wiring has been replaced with Kimber wire, the input and output jacks have been replaced w/WTB connectors, and that's it. currently, it works great, it doesn't sound great, as it has no sound. it's silent (no hum).
Anyway, I would like to build a Tube preamp, as my understanding, this is where the most significant "changes" can be realized. I have a foot in both worlds, I love my REGA turntable spinning vinyl, and I will also play CD/SACD's.
Your suggestions and help is appreciated. Thank you.
Unless the DH500 is for pushing big panel speakers like Maggies or some-such. Otherwise, a nice push-pull tube amp will eat the Hafler.
jeff
Unless the DH500 is for pushing big panel speakers like Maggies or some-such. Otherwise, a nice push-pull tube amp will eat the Hafler.
jeff
Stock or slightly tweaked as done by the OP, yes. OTOH, fully rebuilt by AVA and its a close horse race. Correct speaker matching will decide the outcome. Although it's been some time, I have used AVA rebuilt Dyna and Hafler SS amps. Many of the claims made stand up to scrutiny.
Fact, many a very good sounding rig uses tubed preamplification and 1st rate SS power amplification. Thinking of the amps and speakers as parts of whole is crucial.
Raven. Sowter or Lundahl do the iron.
And/or Toccata
A variatino on the above K&K Phono Preamp Kit Preamplifier with 2003 review
B&W makes good speakers, but they should be mated to SS power amps. A look at the uploaded snip from the N804 spec. sheet shows why. Notice the 8 Ω nominal impedance and the 3 Ω impedance minimum. For the most part, tube amps have modest damping factors. For use with a tubed power amp, the N804s have to be treated as being 4 Ω and their sensitivity has to be derated to 86 dB.
B&W joins plenty of other speaker manufacturers in "spinning" their products' numbers. The claimed sensitivity is with 2.83 V. of drive, but 2.83 V. into 4 Ω is 2 W. Therefore, the claimed 89 dB. sensitivity is (IMO) quite dubious.
B&W joins plenty of other speaker manufacturers in "spinning" their products' numbers. The claimed sensitivity is with 2.83 V. of drive, but 2.83 V. into 4 Ω is 2 W. Therefore, the claimed 89 dB. sensitivity is (IMO) quite dubious.
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Most of the "sound" is where the gain is. In other words a tube running at a gain of 1.0 adds almost nothing. You can't hear it that there is even a tub in the chain. If the tube is providing gain, that it will add something you can hear.
So the only use of tubes, other then for decoration and bragging rights is when it will actually do amplification. That would be either (1) in the power amp or (2) in the phono preamp. But NOT in a line level low or no gain section.
I think you will find that tube equipment is so darn simply you don't need a kit. point to point ott turret board contruction is better than using printed circuits too. You can cut aluminum chasses with hand tools if needs be. It is pretty easy.
Simon, Rozenblit's chassis is decent and the circuitry is OK. However, the OP wants a full function preamp and finding a complete kit for that is not easy.
James, please give us a feel for your skill level. Design is not an issue, as the members can point you at all sorts of reasonable options. Can you do a bit more than "follow the dots"?
I agree.
I really would not go the preamp route unless it is simply something that you want to do to fulfill a bucket list. The sound quality will only be as good as a good solid state preamp, but no better and likely less.
The tube power amp acts as a current drive amp, which behaves differently than a solid state amp (voltage drive amp).
That means the changing impedance of the speaker over the audio spectrum affects the true SPL differently depending on the type of amp.
I contend the "tube sound" of an undistorted amplifier has more to do with this behavior than anything else.
When a solid state amp drives a higher impedance load the power produced goes down. Most speakers have higher impedances at the low end resonance point of the woofer and increasing impedance as frequency goes up with a tweeter. So, solid state amps tend to loose audio SPL and sound a little duller and lacking bass because of that when compared to a valve amp.
The valve amp, with its lower negative feedback, operates closer to a current driven amp and provides more power as speaker impedance rises, providing a somewhat brighter and bassier response compared to a solid state amp that has lots of feedback.
The downside is lower damping with the valve amp. However, when you factor in a passive crossover, that loss is not that significant.
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Speakers and amps form integrated wholes. The OP has B&W N804 speakers, which exhibit 1 or more nasty dips in the impedance curve. With few exceptions, those speakers should be mated to SS power amplification. A Harman/Kardon Cit. 2 refurbished ala Jim McShane is an exception and would work well, with the N804s connected to the 4 Ω taps.
As I read it, reality is a tweaked Hafler DH500 driving the N804s. A full function (phono and line) tubed preamp that gets the most out of what's downstream is what the situation requires. Lots of good options are available and I hope other members will make suggestions. Of course, I'll grind my own axe and suggest designs I'm associated with, but they are far from "the only game in town".
I've uploaded schematics for a tweaked RCA phono section and a 12B4 line stage. That pair would do the job quite nicely. A PSU that provides for the needs of both sections would have to be worked out, but that's NBD.
As I read it, reality is a tweaked Hafler DH500 driving the N804s. A full function (phono and line) tubed preamp that gets the most out of what's downstream is what the situation requires. Lots of good options are available and I hope other members will make suggestions. Of course, I'll grind my own axe and suggest designs I'm associated with, but they are far from "the only game in town".
I've uploaded schematics for a tweaked RCA phono section and a 12B4 line stage. That pair would do the job quite nicely. A PSU that provides for the needs of both sections would have to be worked out, but that's NBD.
We have Troll
Please take your contention to a thread that cares.
OP asked for something specific and you've waded in with flame bait.
That's not going to help the OP at all.
Please take your contention to a thread that cares.
OP asked for something specific and you've waded in with flame bait.
That's not going to help the OP at all.
Thanks, but I think you are badly mistaken.
Actually, my opinion is that he is not going to get what he wants by pursuing the route he outlined.
Your opinion may differ, and that is well, fine and probably appreciated; but you will not find me telling you where to go because I see things differently.
So, in the interest of diversity, it may serve Jhm007 better to hear a wider spectrum of opinions than simply what you feel is appropriate. Would you agree with that?
RTFM
Making it a bit easier is that the Hafler has a 47Kohm input impedance according to the manual
I've seen input SS amp impedances well below 10K which makes driving them properly without an output transformer rather difficult. So the KK kits would be overkill. They're not cheap either.
But neither are the Audio Note kits.
Making it a bit easier is that the Hafler has a 47Kohm input impedance according to the manual
I've seen input SS amp impedances well below 10K which makes driving them properly without an output transformer rather difficult. So the KK kits would be overkill. They're not cheap either.
But neither are the Audio Note kits.
If you truly want Full Function, then you could start with the Bent Audio TAP OEM parts. You get autoformer VCs which can double as outputs if you parafeed, remote control with balance, mute, tape loop and input select (6 inputs), and LCD displays. You then build your preamp around it, as I did with my 26 pre.
It sounds astounding. If you're in NJ let me know and you can stop by and hear it.
PS: It's mated to a 1st rate SS power amp now...at least until the 833C monos are done.
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It sounds astounding. If you're in NJ let me know and you can stop by and hear it.
PS: It's mated to a 1st rate SS power amp now...at least until the 833C monos are done.
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