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fa-schmidt Headphone Council Joined: Dec. 7, 2001 |  Message [#1] posted on: 05-14-2005 04:44 PM CST (US).   |  |  Here we go again: www.fa-schmidt.de/yaha/index.htm Hope you will enjoy it. YAHA stands for Yet Another Hybrid Amp. [Edited by fa-schmidt on 05-15-2005 at 03:33 AM.] |
cmoy Administrator Joined: Apr. 13, 1999 | Message [#2] posted on: 05-14-2005 05:11 PM CST (US). | | fa-schmidt, pls edit the above post. I accidentally deleted the other thread. [Edited by on 05-14-2005 at 05:15 PM.] |
| Thraxeh Member Joined: Apr. 1, 2005 | Message [#3] posted on: 05-15-2005 03:53 AM CST (US). | | the image links arnt working :S |
| fa-schmidt Headphone Council Joined: Dec. 7, 2001 | Message [#4] posted on: 05-15-2005 05:45 AM CST (US). | | Thraxeh: Which browser do you use ? Is www.fa-schmidt.de signed as a trusted site in your browser ? (Dammit, this html stuff is not my world. I tried to save CMOY |
| Thraxeh Member Joined: Apr. 1, 2005 | Message [#5] posted on: 05-15-2005 05:51 AM CST (US). | | Firefox i just tryed with IE and it works. btw, i like the amp, very compact :) i have a OPA2132 opamp, so thats a start. [Edited by Thraxeh on 05-15-2005 at 05:54 AM.] |
| fa-schmidt Headphone Council Joined: Dec. 7, 2001 | Message [#6] posted on: 05-15-2005 05:57 AM CST (US). | | Fixed a problem with scripting. Link should now work better. OPA 2132 should be a good match. |
| cmoy Administrator Joined: Apr. 13, 1999 | Message [#7] posted on: 05-15-2005 04:12 PM CST (US). | | Yay! a portable tube amp!!! Many rechargeable batteries now provide voltages of 1.4 to 1.5V, so you might be able to get away with as few as 8 AA batteries. How low can the 12VDC supply fall and still allow the amp to operate? What is the gain on the tube input stage? |
| sijosae Administrator Joined: N/A | Message [#8] posted on: 05-16-2005 02:44 AM CST (US). | | Great Altoids tin hybrid amp. I'm interested in low voltage amp. It looks good solution. As a portable only use, instead of LM317-CCS, 5 x AA-size rechargeable batteries seems good choice for the heater supply. |
| fa-schmidt Headphone Council Joined: Dec. 7, 2001 | Message [#9] posted on: 05-16-2005 03:32 AM CST (US). | | CMOY: Yes, 8 NiMh do the job. The supply voltage can go as low as 10VDC before the CCS stops working. The gain of the tube stage is 10..15. It depends a bit on the Sijosae: |
| evo HeadWizer Joined: Jul. 18, 2004 | Message [#10] posted on: 05-19-2005 07:10 AM CST (US). | | Hi fa-schmidt, sorry but the link to the 'circuit diagram' in your YAHA page doesn't work. |
| fa-schmidt Headphone Council Joined: Dec. 7, 2001 | Message [#11] posted on: 05-19-2005 07:43 AM CST (US). | | evo: Thank you. I will fix that link asap. (The contents that link should show is the same as in the picture at the beginning of the article.) |
| RainerB Headphone Council Joined: N/A | Message [#12] posted on: 05-20-2005 05:39 AM CST (US). | | Hi fa-schmidt, very, very interesting. I still have some tubes (E88CC, 12AX7, 6922 etc.) for a tube amp but haven't made it to build an amp up to now. The design is very simple, perhaps I will give it a try in the next time. How about higher supply voltages? Did you try to use 18V or more? Depends on the opamp, I know. Rainer [Edited by RainerB on 05-20-2005 at 05:47 AM.] |
| fa-schmidt Headphone Council Joined: Dec. 7, 2001 | Message [#13] posted on: 05-20-2005 06:14 AM CST (US). | | This amp will truly benefit from higher supply voltages. It probably will be less portable, then. Using higher B+ calls for adjustment of the plate resistor Sure, the opamp supply voltage is another criteria. The NJM opamp is good for 36VDC unipolar. (Dammit. Thereīs a typo in the schematic. Itīs NJM 4556, not |
| Tomo Headphone Council Joined: May 4, 1999 | Message [#14] posted on: 05-21-2005 06:00 AM CST (US). | | Hey, Count me in. I found a nice SWITCHING(!!) PSU going probably around 30V or so. (Yesh me a heretic) Thank you for putting this up. I was going totally non-tube mentally as well as physically. I needed some glass in my life. ;) I am gonna go chasis hunting next weekend. Tomo |
| fa-schmidt Headphone Council Joined: Dec. 7, 2001 | Message [#15] posted on: 05-21-2005 01:14 PM CST (US). | | Hi Tomo ! Nice to hear from you again. For home use i bought a switched ps giving 12VDC@1200mA. Good hunting ! (I know you donīt drink so a vaccum tube is what you need). |
| RainerB Headphone Council Joined: N/A | Message [#16] posted on: 05-23-2005 04:55 AM CST (US). | | Hi fa-schmidt, the link to the YAHA schematics in your site is still wrong. Rainer |
| fa-schmidt Headphone Council Joined: Dec. 7, 2001 | Message [#17] posted on: 05-23-2005 06:25 AM CST (US). | | Thanks, Rainer. I couldnīt get it corrected during the weekend and i am afraid that i donīt find the time to fix it within the next few days.. Iīll be offline from Tuesday to Saturday due to business affairs. |
digi01 HeadWize Fanatic Joined: Dec. 3, 2002 | Message [#18] posted on: 05-26-2005 04:30 AM CST (US). | | very cute design,I will try. |
| Tomo Headphone Council Joined: May 4, 1999 | Message [#19] posted on: 05-27-2005 07:36 PM CST (US). | | Tomo Reporting from Tokyo! I have completed and listening to my new AD-HOC YAHA amp. Pretty cool. I never knew low voltage running tube amp would be pretty decent. Why ad-hoc? I had to make few modifications. I didn't have LM317 in stock so I used LM337. (This has to be connected to GROUND not to +B. This is on LM337 spec sheet.) And, I COULD NOT GET A HAND ON NJM4556! They had NJM4558 and NJM4580. I tried few other stores in Akihabara with negative hits. :( Anyways, so I picked up an NJM4580. It's a pin-compartible opamp with 50mA (to short). My plate resistor is around 50kohms. And, the output resistor is 500 ohms(!). I smashed my old kit and pulled them. (Somehow I lost entire resistor stock. ...) Lastly, my current source resistor is 4.7 ohms. Supposedly I should be getting 200-300mA. I am a bit worried because the tube is pretty bright and beautiful. Tomo P.S. I am using Ei ECC88. Did you know Ei survived the civil war? I think it's a wonderful news! I also have Tesla ECC88 to try out. |
| Tomo Headphone Council Joined: May 4, 1999 | Message [#20] posted on: 05-27-2005 07:39 PM CST (US). | | Hey, JRC is no longer producing NJM4556. Poo! T |
| RainerB Headphone Council Joined: N/A | Message [#21] posted on: 05-28-2005 02:06 PM CST (US). | | Also positive results from the other side of the world. :-)) Made a YAHA prototype yesterday:
This time with 22V supply, 6922, plate resistor has to be 470k for half supply at plate, output via OPA2134, output caps = 1000uF. The on/off bump in the headphones is neglectible, perhaps due to the 3 x 4700uF caps in the power supply. Sound: somehow very even, warm and also refined. The sound is very different from pure opamp-based amps. I think it will get a final version with 24V or more supply, Rp=440k + 250k pot. One question: LM317 with 2x8.6 ohms makes 200mA filament current. But why is the voltage over 4-5 neraly 18V????? Shouldn\\'t it be 6.3V? Confusing. Rainer [Edited by RainerB on 05-28-2005 at 02:09 PM.] |
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Đ Chu Moy, 2001.