Here are some shootouts I found online:
1 RGN2504 Telefunken mesh My favorite, best articulation, detailing and life.
2 RGNx004 Telefunken mesh 2004 and 4004, almost identical in sound, v. clear + clean.
3 AZ1 Telefunken mesh Really nice rectifier, clean, musical, liveliness.
4 UX-280 RCA/Cunningham Very musical, sweet, detailed in mids, highs pretty good.
5 83 RCA Very detailed high-mids/highs, good response.
6 80 (ST) RCA A bit more mellowed than the 80 globe, not as precise/accurate.
7 UX-281 RCA/Cunningham A bit like the 80, somewhat warmer, more force in lows.
8 866A RCA In big amps only. Very clear, sometimes a bit noisy.
9 5Y3GT RCA Very neutral, good for preamps etc, clean, a bit dry.
10 5U4G RCA Sound is dull, not as detailed, warm. The 300B of rectifiers.
GZ34/37 etc These types all sound very grainy and closed in, just not my cup of tea.
1. AZ-1 Vintage by "Valvo" ("brass" pins, ST shape balloon)), manufactured before WWII. Sounds so relaxing. Apsolutely the best. Like TFK AZ-1, but with soft highs. Speakers disappear "far away behind the back wall". Wonderful violins, mandolins and female vocals.
2. AZ-1 "Telefunken" balloon - beautiful. Excellent 3D, very flat, extra-speed bass. But with ng highs inferior to Valvo
3. EZ-80 "Miniwatt", D-getter best of EZ-80/81 types. Sounds clean, flat and forward.
4. GZ-34 "Siemens" Mazda-Belgium sounds very good, but too much brightnessssssssss,
1. AZ1 mesh
2. WE274B
3. 83 - tuneful and open. I would suggest staying away from the 83 tube. Mercury is not our friend
1. 5Y3 my personnel fav. Airy and deep bass. Fast, transparent. Bass is deep. Far better than GZ34. I run this tube a lot, hard and over spec. Go for brown base types. Or a british type where they are more transparent and lower base. Ken rad are really good and wet bass.
2. 80- Ancestor of the 5y3 , rolled of highs but super mids. I use type 80 with a 5y3 mix in my set up to balance things
3. 5R4. Super highs, fast,airy but thin sounding and light on body. Go for non-potato masher.
1 RGN2504 Telefunken mesh My favorite, best articulation, detailing and life.
2 RGNx004 Telefunken mesh 2004 and 4004, almost identical in sound, v. clear + clean.
3 AZ1 Telefunken mesh Really nice rectifier, clean, musical, liveliness.
4 UX-280 RCA/Cunningham Very musical, sweet, detailed in mids, highs pretty good.
5 83 RCA Very detailed high-mids/highs, good response.
6 80 (ST) RCA A bit more mellowed than the 80 globe, not as precise/accurate.
7 UX-281 RCA/Cunningham A bit like the 80, somewhat warmer, more force in lows.
8 866A RCA In big amps only. Very clear, sometimes a bit noisy.
9 5Y3GT RCA Very neutral, good for preamps etc, clean, a bit dry.
10 5U4G RCA Sound is dull, not as detailed, warm. The 300B of rectifiers.
GZ34/37 etc These types all sound very grainy and closed in, just not my cup of tea.
1. AZ-1 Vintage by "Valvo" ("brass" pins, ST shape balloon)), manufactured before WWII. Sounds so relaxing. Apsolutely the best. Like TFK AZ-1, but with soft highs. Speakers disappear "far away behind the back wall". Wonderful violins, mandolins and female vocals.
2. AZ-1 "Telefunken" balloon - beautiful. Excellent 3D, very flat, extra-speed bass. But with ng highs inferior to Valvo
3. EZ-80 "Miniwatt", D-getter best of EZ-80/81 types. Sounds clean, flat and forward.
4. GZ-34 "Siemens" Mazda-Belgium sounds very good, but too much brightnessssssssss,
1. AZ1 mesh
2. WE274B
3. 83 - tuneful and open. I would suggest staying away from the 83 tube. Mercury is not our friend
1. 5Y3 my personnel fav. Airy and deep bass. Fast, transparent. Bass is deep. Far better than GZ34. I run this tube a lot, hard and over spec. Go for brown base types. Or a british type where they are more transparent and lower base. Ken rad are really good and wet bass.
2. 80- Ancestor of the 5y3 , rolled of highs but super mids. I use type 80 with a 5y3 mix in my set up to balance things
3. 5R4. Super highs, fast,airy but thin sounding and light on body. Go for non-potato masher.
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Hi Felipe.
This is my #26 preamp raw HT supply.
242V RMS AC in, AZ1 mesh, CLCLC and two SSHV2 (2*20mA).
Attachments
Hello euro21,
Thanks to share your PSU schematic, I fixed my issue: I used 6VAC tx for AZ1 heaters with 1R in series to lower to 4VAC, I measured 4,90VAC in AZ1 heaters instead 4VAC so I added 1R more in series to have 2R and now I have 4VAC at the AZ1 heaters
Cheers
Felipe
If you ground C3 instead of C1 it will sound better. And as the result SS rectifier will "sound" less different from vacuum rectifier.
Hi Jeffrey,
what is the advantage you are seeing in dual mono supplies for such a preamp? Even in my most elaborate preamps I have a common B+ supply. Decoupling between channels is done with separate LC filter sections with high inductance coils. Filament supplies I keep separate
Best regards
Thomas
what is the advantage you are seeing in dual mono supplies for such a preamp? Even in my most elaborate preamps I have a common B+ supply. Decoupling between channels is done with separate LC filter sections with high inductance coils. Filament supplies I keep separate
Best regards
Thomas
Just seeking the last iota of seperation of channels with a common power chord. Also the rest of my system is completely dual mono and I have a fetish for bi-lateral symetry
JD
JD
Yes please!
As many have asked me for my latest schematic, here it is:
http://www.bartola.co.uk/valves/dht-pre-amplifier/26-dht-pre-amplifier-gen2/
Still early days playing with it so may be tuning it a bit..
Ale
I'm just wondering about the glow tubes here. The way I understood it you used a .056uF bypass cap rather than 1uF (edit: 0.1uf meant). Also you don't put any capacitance after the glow tubes. You have 10uF, though this is separated by a 3.3K resistor. I thought glow tubes started to misbehave when you added capacitance.
If you have this up and working then clearly it works. Maybe we haven't been reading the same theory - I just read a lot of stuff on various posts about this.
Does anyone have definitive answers to using capacitors with glow tubes?
If you have this up and working then clearly it works. Maybe we haven't been reading the same theory - I just read a lot of stuff on various posts about this.
Does anyone have definitive answers to using capacitors with glow tubes?
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Andy,
Bypass cap is 100n, not 1u. Didn't have a 56n around and it seems that the VR don't complain about that.
The additional RC is a voltage drop/ filtering stage as per Gary Pimm's.
See this:
http://www.pimmlabs.com/web/Tabor3s.gif
Perhaps an expert in VR can explain why with CCS feeding the VR additional capacitance doesn't make it to oscillate, etc....
Ale
Bypass cap is 100n, not 1u. Didn't have a 56n around and it seems that the VR don't complain about that.
The additional RC is a voltage drop/ filtering stage as per Gary Pimm's.
See this:
http://www.pimmlabs.com/web/Tabor3s.gif
Perhaps an expert in VR can explain why with CCS feeding the VR additional capacitance doesn't make it to oscillate, etc....
Ale
I wasn't aware of this - it could be useful since you can adjust the final voltage more accurately. What's the minimum size resistor to give adequate separation?
Also it could help with strike voltage if the HT is restricted.
Hi,
Wish add my newborn 26 pre to the list:
It sounds very, very well. I'm impressed for the strings and female voices.
Set up is two ux 226 (one radiotron, the other a strange green base echotron) with filament bias at 10 V, plate voltage at 150 V -around 6 mA- on two hammond 156c for channel like Andy's pre. Supply is, as Rod suggestion, a mix graetz of uf4007 and a valvo az1 mesh plate with a c-l-c-l-c (2 uF oil-15 H Hammond-50 uF polarized-15 H- 100 uF ) for a raw line of 175 V inijected on a SSHV 1.
Problem to solve in the next:
1) great microphonic effect.... all noises generated near pre will sound on speaker
2) Two box that will limit at maximum hum captation.
Thanks to all participants to this great thread. I've learned enormous knowledge reading your post.
Ciao,
Anto
Wish add my newborn 26 pre to the list:
It sounds very, very well. I'm impressed for the strings and female voices.
Set up is two ux 226 (one radiotron, the other a strange green base echotron) with filament bias at 10 V, plate voltage at 150 V -around 6 mA- on two hammond 156c for channel like Andy's pre. Supply is, as Rod suggestion, a mix graetz of uf4007 and a valvo az1 mesh plate with a c-l-c-l-c (2 uF oil-15 H Hammond-50 uF polarized-15 H- 100 uF ) for a raw line of 175 V inijected on a SSHV 1.
Problem to solve in the next:
1) great microphonic effect.... all noises generated near pre will sound on speaker
2) Two box that will limit at maximum hum captation.
Thanks to all participants to this great thread. I've learned enormous knowledge reading your post.
Ciao,
Anto
