 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
24.140.110.227
In Reply to: RE: Listening to my New Korneff Clone 45 SET Amps ................. posted by Cut-Throat on March 26, 2021 at 13:57:06
C-T,
Why are you bi-amping with 115dB horns?
The TAL SE 45's should have enough power for "wideband" audio reproduction.
Let the amplifiers show what they can do in the listening room .
DT 667
Follow Ups:
A few reasons.... First of all, it is working perfectly now. It is seamless, powerful and Musical. And I am not Bi-Amping the 115db Oris Horns. I am Bi-Amping the Entire System, which includes the 100db Khorn Bass Bins. The only Amp attached to the 115db Oris Horns ARE the TAL 45s.
When I got my Oris Orphean Horn System, the designer Bert Doppenberg of Holland recommends the Bi-Amp Configuration. And specifically the Hypex Amplifiers for the Bass Bins of your choice. All of his Bass Bins use a separate Bass Amp. Even with High Power Solid State Amps on his Horns. (Bert Prefers Solid State Amps). The Hypex Amps have a built in Active Crossover for the Bass Bin. The Orphean Horn Mid-Range and Tweeter use a passive crossover for cutoff Freqs of 270hz and 7,000 Hz. I have the Khorn Bass Bin cutoff Freq set at 270 Hz. --
Before I got the Oris Horns, I was using Altec Multicells and the Bass was sorely lacking even though the Khorn/Altec System was 104db. This was with 45 amps and 2A3 Amps. Amps were driven into clipping when volume hungry friends came over. Did the Bass bins make noise? -- Yes, but it was not the Controlled, Quick and Powerful Bass that I have now. And it also 'taxed' the SET amplifiers to clipping during Big orchestral performances (Think Firebird Suite and 1812 Overture) and Heavy Rock.
So, Been there, done that and 45 amps alone won't do it for me across all music spectrums. I switched to Oris Horns/Bi-Amping 7 years ago and have never looked back.
If you're ever in the Minneapolis Area, give me a shout and you can listen for yourself. I'll even provide the libations of your choice. :-)
I wish I had more time to travel and hear what other people are doing.
Your system sounds very interesting.
Enjoy the TAL SE 45's!
DT 667
"The Orphean Horn Mid-Range and Tweeter use a passive crossover for cutoff Freqs of 270hz and 7,000 Hz."
What do you do to keep the bass out of the 45 amplifier?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Not sure I understand your question. But the Bass is kept out of the Oris Horn.... The full signal from the pre-amp still 'goes into' the 45 Amplifer, as well as the Hypex Amplifer.http://www.bd-design.nl/contents/en-us/d71.html
I did try a Marchand Active Crossover once, that would filter out the Bass before it reached the Amp, but it was a Mass of extra cables and added more hum to my system than I've ever heard before.
Edits: 03/27/21 03/27/21 03/27/21
I understand that. I am asking what do you do to keep the bass out of the 45 SET amplifier?Even though you have a passive crossover keeping the bass out of the horn, if you don't do something to keep the bass out of the 45 SET amplifier the load line for the mids and highs will follow an elliptical load line because of the presents of the bass. No gapped output transformer has enough inductance to properly deal with low bass frequencies. This leads to distortion of all the frequencies.
Try this, add your best .015uf capacitor in series with the 100k input impedance of the 45 amplifier. I like the Russian Silver mica caps.
This will create a 6db high pass filter at about 100Hz and greatly improve that amplifiers performance in the mids and highs without changing your 270Hz crossover point. The load line for the mids and the highs will become much more "resistive" leading to less harmonic distortion.
Voltsecond did a study of inductance and elliptical load lines and made the very point I am trying to share with you.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 03/27/21
I needed a high pass filter at 70Hz, so I added a .0022uF mylar cap to the input stage grids my of SE DC breadboard amp.
The circuit uses a 6SN7 with a 1Meg grid leak resistor.
THD @ 1W/1KHz increased by .3%
The caps are cheap and outer foil orientation was easy to determine, not sure if that is the reason why or not.
DT 667
And His response was the following:
"Yes, true but ...
Depending on the used amplifier you can or you shouldn't. If your main amp is capable to give good bass signals without noise (without the need for much power) then your present connections are optimal.
This way you keep the harmonic signature of the sound fed into the bass system the same for optimal sounding integration.
***************************************************************************************
If your main amp is not capable (makes too much noise or uses relative small output transformers then it can be beter to use a pre-amplifier or split the signal on the input of your main amplifer and connect from there to your bass amplifier. Make sure that the input impedance of both amps are not too low, your source might not be able to drive this load if it has a relative high output impedance (TVC's do not like this at all!).
As long as the output impedance is roughly 10 times lower then the combined input impedance then you're good to go. A pre-amplifier with output a buffer or 2 buffered outputs work best."
********************************************************************************
Upon further discussion with him and sending him the Schematics of My Amplifier, His recommendation was to feed the Full Signal to amp.
.
Have Fun and Enjoy the Music
"Still Working the Problem"
I removed some carbon comp grid stoppers from the 6SN7 driver stage relay sockets on my breadboard.My ARTA test setup uses a 100K pot to trim voltage coming out of the sound card. It is housed in a plastic box with rca jacks for in/out.
For some reason, I am getting odd THD readings from on the left channel, so I think the grid might be going into oscillation as I turn the pot.
A test signal directly from the soundcard into the amp causes no problems.
I will have to investigate further and try to input cap mod again.
DT 667Edit : found an issue related to power supply returns.
Once corrected, ARTA measurements seemed to normalize.
I will need to re-test the input cap mod again.
Edits: 04/01/21 04/01/21 04/07/21
Yes, but did it sound any different?
Yes, but did it sound any different?No, I did not listen.
I might reinvestigate with some different film caps to see if the distortion issue happens again or not.
FWIW, I also noted an small increase in THD at 100Hz as well.
Not what I was hoping to see.
I would leave the TAL SE 45's unmodified.
Don't void the warranty.
DT 667
Edits: 03/29/21
Did you mean 1 Meg ? -- I'm just trying to document the Modification.
Edits: 03/27/21
.
Have Fun and Enjoy the Music
"Still Working the Problem"
on the input stage so I'm thinking .022 uf for about 60Hz, the lower reasonable limit to my folded mid-bass horn?
Makes sense.
Or just a smaller coupling cap between the driver and the 300B?
.
Have Fun and Enjoy the Music
"Still Working the Problem"
.
Have Fun and Enjoy the Music
"Still Working the Problem"
.
Have Fun and Enjoy the Music
"Still Working the Problem"
I had not heard of this.... I won't be modding anything for awhile, but I'll save it for future reference. Here is the Schematic... Could you tell me exactly where you'd put that Cap?
With a 1meg input impedance the cap only needs to be a .00159ufA .0015uf would work just fine.
This is a big deal. You will hear immediately the mids and highs "clean up".
Do yourself a favor and just try it.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 03/27/21 03/27/21
With a Cap that small, I should be able to afford the highest End Cap made! -- Could you provide me with a link to the 'Study' you had mentioned?
Mike, on the Magnequest forum here on the AA, used to host the paper by
Voltsecond but it's not there anymore.All output transformers have a limited amount of inductance. Single ended output transformers need to have a gap so the idle current for the output tube doesn't saturate the core. When a gap is placed in the core of a transformer the inductance goes way down. The inductance can be brought back up by winding more wire around the core but there are limits. Too much wire and you will began to lose highs because of the winding capacitance. The end result of all the this is that SET transformers do not have a ton of inductance. The lack of inductance means that the reactance of that inductance will be small for the lower frequencies and that is what causes the elliptical load line.
If you allow the lower frequencies to reach the output transformer the load line becomes elliptical instead of the straight load line we think of when we're dealing with a plate resistor. An elliptical load line causes the tube to operate in a less linear part of the operating curve for part of the wave form.
The part that most people miss (and the part that Voltsecond points out) is that once there are low frequencies present in the output transformer all the frequencies have to follow that elliptical load line, not just the bass frequencies. If you can keep the low frequencies out of the transformer the load line will be much more like a resistive load line and there will be less distortion.
Even if you don't follow what I am trying to explain or if you don't believe me, it costs very little to try this and it is totally reversible.
After reading Voltsecond's paper, I placed caps in front of my SET 300b amps driving my midrange and tweeter and was shocked at the improvement.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 03/27/21
I agree with the main premise and suggestions.
I'd just like to add that the inductance and capacitance (and it affect on high-frequency performance) seems often overstated. A good winder using suitable materials and techniques should be able to achieve sufficient inductance and high frequency extension for most common SE output requirements. A 5k:8 ohm, 35mA transformer ain't that tough.
And I'm not suggesting a "perfect" transformer can be wound, or that there is only one right way etc... that easing of inductance for a different set of compromises is not desirable for some tastes in some systems.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
I don't know of any gapped output transformers that have enough inductance to prevent an elliptical load line in the presents of low bass.Let me explain a little more. I don't play bass using SET transformers for three reasons. One, not enough power, 2 too low a damping factor and 3 the subject at hand.
I have seen sims that show the elliptical load lines for a "normal" SET output transformer at low frequencies and it's not pretty. I have also seen sims of the load line when the bass is limited to 200Hz for the same "normal" SET output transformer. With the bass frequencies limited the load line almost looks like a resistive load line resulting is much less harmonic distortion.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 03/27/21
As I said, I agree with your point in principle and would do similar if biamping. I think biamping is great approach for the reasons you suggested.
My point was that the severity and significance of some of the compromises mentioned can be overstated, especially where quality output transformers are concerned, and IME don't preclude fine or enjoyable performance used full range in a suitably matched system.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
.
Have Fun and Enjoy the Music
"Still Working the Problem"
nt
I wanted to stay away from your 270Hz crossover point but make sure to limit the low bass as much as possible to your output transformer.
If you're 270Hz crossover is 6db then you could use a .00056uf cap instead and get rid of the passive 270Hz crossover part but that would leave your horn subject to any bumps that might happen in the amp so it would not be as safe.
Or, if your 270Hz crossover is 12db then you could change it to 6db and have 6db at 270Hz before the amp and 6db at 270Hz after the amp and still be safe-ish.
But let's not get too off track. Limit the low bass to the amp and enjoy the improvement.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Seems a bit hard to find for me..
Edits: 03/27/21
http://www.soniccraft.com/index.php/film-capacitors-rel-cap-rte-c-301_48
I'm having trouble too.
Why is the grid resistor 1 meg?
You could get two 1000pf (.001uf) and two 500pf (.0005uf)
Place one 1000pf in parallel with one 500pf. That would be one .0015uf cap and that will work.
Against the 1meg grid resistor it would make a 6db per octave high pass filter with a -3db point of 106Hz.
https://tubedepot.com/products/silver-mica-1000pf-500v?utm_source=google&utm_medium=cpc&adpos=&scid=scplpCP-SM-1000-500V&sc_intid=CP-SM-1000-500V&gclid=EAIaIQobChMIvYjtuKbR7wIVfyGtBh1UYgR_EAQYBCABEgJiAvD_BwE
https://tubedepot.com/products/silver-mica-500pf-500v?utm_source=google&utm_medium=cpc&adpos=&scid=scplpCP-SM-500-500V&sc_intid=CP-SM-500-500V&gclid=EAIaIQobChMIvYjtuKbR7wIVfyGtBh1UYgR_EAQYASABEgJ2uPD_BwE
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
What do you think of these?
https://www.ebay.com/itm/0015-uF-1500pf-630-volt-Polystyrene-Capacitor-NOS-QTY-20-ea-P510/192162051515?hash=item2cbdc035bb:g:fJQAAOSwE1xbyhgr
or
https://www.ebay.com/itm/2-NOS-Vintage-Pyramid-0015-uf-300v-PIO-Capacitors-Vitamin-Q-Oil-Treble-Bleed/122629572318?hash=item1c8d4ac6de:g:TMAAAOSwjC9ZgoWT
or
https://www.ebay.com/itm/2-NOS-Vintage-Fast-0015-uf-300v-PIO-Capacitors-Vitamin-Q-Oil-Treble-Bleed-Caps/112507170078?hash=item1a31f32d1e:g:21wAAOSw3IdZgoZL
Polystyrenes are pretty good sounding caps.
I don't like PIO caps anymore, I use to.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
I have a 3535Pf (.003535uf) Russian silver mica cap against a 330k ohm grid resistor for a -3db point of 136Hz. My midrange speakers are about 3db down and falling at 200Hz all by themselves. I use an electronic (opamp based) low pass filter at 200Hz. in front of the SS amp I use to drive my JBL 2231s woofers.I find the Russian silver mica caps to be very transparent. I use them in my phono preamp also.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 03/27/21 03/27/21
https://www.hificollective.co.uk/search/site?title=.0015
The Audio Note Tin Foil Capacitor is not to bad.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
"Why is the grid resistor 1 meg?"
I don't know, you'd have to ask Jeff Korneff :-)
It goes back to the Article in 'Glass Audio' to a Schematic from Eric Barbour, where Jeff Korneff got his initial design. Here is the Schematic from that Article.
It would be nice to use a Single Capacitor.
You can make that grid resistor just about any value you like.
I use the 330k on my first stage because it fits well and gives me the frequency I want with the sliver mica caps I had. And it's plenty high as to not load down my preamp.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Can't you get a capacitor close to crossover FQ and fine tune with the grid resistor value?
Wouldn't it be cheaper to swap out resistors than caps?
What formula do you use to calculate crossover FQ?
What can a 500 ohm output impedance preamp be comfortable with?
"Can't you get a capacitor close to crossover FQ and fine tune with the grid resistor value?"
That's what I do.
"What formula do you use to calculate crossover FQ?"
-3db point of the filter = 159155/(cap value in uf times resistance value)
"What can a 500 ohm output impedance preamp be comfortable with?"
Almost anything. The rule of thumb is 1:10 so it will drive 5k without trouble. Just don't forget about capacitance reactance at the high frequencies which is in parallel with the grid resistor value. That would include cable capacitance and the Miller capacitance of the tube being driven. Also the source needs to be able to supply the current that capacitance reactance will require.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
T
.
Have Fun and Enjoy the Music
"Still Working the Problem"
nt
Sometime this year... It's quick and easy to do.
.
Have Fun and Enjoy the Music
"Still Working the Problem"
| FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
||||||||||||||
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2024, Audio Asylum, all rights reserved ]
