Hi all can any one tell me the best way to reduce the gain on this preamp as it is in front of a SS power amp with 1.28v input 135w 8ohms and 12k.
I'm new to tube stuff so some help here would be great.🙂
I'm new to tube stuff so some help here would be great.🙂
In many cases the best way to reduce the gain of a preamp is to omit it from the system. That unit appears to have a gain of 9 (19dB) which is far too high for a line stage. You could add a -19dB attenuator.
That's what I was thinking may be a stepped attenuator home made 12steps around 50k as the main volume is a crappy 100k pot that will be changed to a attenuator to. The pre is not made yet I want too sort this gain out as I only want 2-2.5v max!
I have to still buy the tubes this my be anther option to drop the gains
I have to still buy the tubes this my be anther option to drop the gains
ZSP1 preamp gain.
That's what I was thinking may be a stepped attenuator home made 12steps around 50k as the main volume is a crappy 100k pot that will be changed to a attenuator to. The pre is not made yet I want too sort this gain out as I only want 2-2.5v max!
I have to still buy the tubes this my be anther option to drop the gains
That's what I was thinking may be a stepped attenuator home made 12steps around 50k as the main volume is a crappy 100k pot that will be changed to a attenuator to. The pre is not made yet I want too sort this gain out as I only want 2-2.5v max!
I have to still buy the tubes this my be anther option to drop the gains
Most digital sources will give you 2V out. No need for a line stage. However, if for some reason you really want one (e.g. mild FX box) then you can sometimes reduce the gain by adding or increasing cathode degeneration. This raises anode impedance so it is important that the voltage amplifier is then followed by a cathode follower - which I believe is the case with the unit you are considering.
There are very few mainstream valves with sufficiently low mu for a sensible line stage. 12B4 is one possibility, but I believe they have a reputation for being microphonic?
There are very few mainstream valves with sufficiently low mu for a sensible line stage. 12B4 is one possibility, but I believe they have a reputation for being microphonic?
Thanks for ya input!
I no what you saying maybe I'm going down the wrong road? At the moment I'm just using
A 10k attenuator as a volume control from cd to amp I do in joy the sound great sound stage and so on but just a bit thin and bright.
I also want to add a phono stage for my MC. I was thinking a tube preamp might tone things down a bit?
I no what you saying maybe I'm going down the wrong road? At the moment I'm just using
A 10k attenuator as a volume control from cd to amp I do in joy the sound great sound stage and so on but just a bit thin and bright.
I also want to add a phono stage for my MC. I was thinking a tube preamp might tone things down a bit?
'Thin and bright' may be a speaker problem. A good tube preamp will not tone things down. A bad one might, but you can make a bad preamp using any technology.
Funny you should say that my speakers are custom made about 10years ago they are running a scan-speak 8" 21w/8554 and a D28-2 dynaudio I have never been happy with the crossover as it is a to component type with a 10uf cap and a .68mH inductor 1st order 6db. I found the highs were to bright and the mids all over the place but bass ok plus power handling a problem! As I'm not
Very good with crossovers I sent all the specs to madisound in the US and they have come up with a new network that should sort it out I hope? The network looks like a 12db 2ed order with impedance correction. I'm at the stage of sourcing the parts. As you say this could be the hole problem. What I will do is sort this out 1st and go from there!
I will post how I go with the speakers. And thank you so much for you feed back. I might have been getting a little ahead if my self. Oh I did contact Steve at decware got a big 0.. As you probably worked out I have next to no experiences with valve amps but would like to have a play with them! I no there is a nice headphone pre amp the Decware made thet is ideal for running SS power amps. If any one out there has the schematic for it I would like to have a go at building it. PS Cheers DF96.
Very good with crossovers I sent all the specs to madisound in the US and they have come up with a new network that should sort it out I hope? The network looks like a 12db 2ed order with impedance correction. I'm at the stage of sourcing the parts. As you say this could be the hole problem. What I will do is sort this out 1st and go from there!
I will post how I go with the speakers. And thank you so much for you feed back. I might have been getting a little ahead if my self. Oh I did contact Steve at decware got a big 0.. As you probably worked out I have next to no experiences with valve amps but would like to have a play with them! I no there is a nice headphone pre amp the Decware made thet is ideal for running SS power amps. If any one out there has the schematic for it I would like to have a go at building it. PS Cheers DF96.
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