What am I experiencing?

KenCalgary · 2nd October 2010, 12:49 AM

I have just completed my first tube preamp using John Broskie's Aikido line and Tetra phono PCBs. It replaces a solid state preamp but still plugs into my solid state amplifier. It has very little (perhaps 3 hours) burn in time. The line stage (e.g., when using the CD player) is quiet, clear and delightful. All the tubes are NOS organ tubes.

The phono stage produces a lot more detail than did the SS preamp. So much so that groove noise (and/or recording tape hiss on older classical LPs) is very obvious. It isn't a problem on newer well pressed reissues. There also seems to be an emphasis on high frequencies; for example sibilance comes through on several LPs.

The strange thing is that much of this white noise (if that is what it is?) recedes or goes away after an hour or so of listening.

Since I have no experience with tube equipment I was wondering if:
1) Tube equipment needs to warm up before sounding proper?
2) The tubes/wires/etc. need some burning in time?
3) There is a wiring/soldering/other construction problem that is causing this?
4) Something else?

Arnulf · 2nd October 2010, 04:52 PM

Quote:

Originally Posted by KenCalgary

1) Tube equipment needs to warm up before sounding proper?

Yup, give it a minute or a couple of minutes to warm up to the working temperature. This is very much unlike solid-state.

Quote:

2) The tubes/wires/etc. need some burning in time?

W00tLOL

Quote:

3) There is a wiring/soldering/other construction problem that is causing this?

Mostlikely: no.

Quote:

4) Something else?

Mostlikely: yes. I have never met a tube amplifier that didn't hiss on its own. A simple test to perform is to short the input (use a piece of uncoated wire, a leg piched off a resistor or something like that). UIf it still hisses, it's your preamp. If it doesn't, it's someting ahead of your preamp (either the recording itself or the reading mechanism).

DF96 · 2nd October 2010, 07:34 PM

Double-check the components in the RIAA network(s) - it is possible that the HF cut is wrong, perhaps by a factor of 10 (7.5us instead of 75us). After a while listening to it you will get used to it and so not notice it so much. If possible, both re-check the component markings/colour codes and measure them with a DVM.

2nd October 2010, 12:49 AM	#1
KenCalgary diyAudio Member Join Date: Nov 2009	What am I experiencing? I have just completed my first tube preamp using John Broskie's Aikido line and Tetra phono PCBs. It replaces a solid state preamp but still plugs into my solid state amplifier. It has very little (perhaps 3 hours) burn in time. The line stage (e.g., when using the CD player) is quiet, clear and delightful. All the tubes are NOS organ tubes. The phono stage produces a lot more detail than did the SS preamp. So much so that groove noise (and/or recording tape hiss on older classical LPs) is very obvious. It isn't a problem on newer well pressed reissues. There also seems to be an emphasis on high frequencies; for example sibilance comes through on several LPs. The strange thing is that much of this white noise (if that is what it is?) recedes or goes away after an hour or so of listening. Since I have no experience with tube equipment I was wondering if: 1) Tube equipment needs to warm up before sounding proper? 2) The tubes/wires/etc. need some burning in time? 3) There is a wiring/soldering/other construction problem that is causing this? 4) Something else?

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Experiencing problems to insert tubes	talaerts	Tubes / Valves	6	29th January 2007 06:38 PM
experiencing stability problems in my simple mic preamp	Dominique	Solid State	16	24th June 2005 08:36 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

2nd October 2010, 07:34 PM	#3
DF96 diyAudio Member Join Date: May 2007	Double-check the components in the RIAA network(s) - it is possible that the HF cut is wrong, perhaps by a factor of 10 (7.5us instead of 75us). After a while listening to it you will get used to it and so not notice it so much. If possible, both re-check the component markings/colour codes and measure them with a DVM.