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A friend sugested that a passive pre (eg Creek or DPA) could not drive a valve amp. Any thoughts?
steve r
Follow Ups:
I have used the passive mode of a Melos Sha Gold to good effect. I never liked the Melos' active outputs with this amp They also do not think that a SS preamp will be a good match, but I really like the results when I hook up the pre out from my Accuphase E-406 integrated with the Baron.Currently, I am searching for a tube or passive preamp that'll be better than both of these. I have a list of possibilities, but am unable to audition any so far. Also, most are too expensive for me to splurge on at this time, so I'll have to set aside the funds.
Happy listening...RR
Funny you should ask...I just replaced a Cary integrated with an FT Audio LW-1 passive and a Conrad-Johnson MV55. Sounds pretty fine, actually. Has bass and dynamics. It depends on how well the equipment matches; also, interconnect length should be short.
If you talk to Paul Lam (who sells the FT Audio), he'll have some insight on whether your current components will work with a passive/valve combo.
I have been using the Silver Rock transformer/pot. volume control with no problems into both VV45 and 2A3 amps.
Building a system around a passive unit is a nightmare. You need to have ALL the system in tune with the special requirements a passive needs to works properly. You need a high input impedance and sensitivity at the power amps (ideally higher than 100 Kohms and 1 volt sensitivity or better for full output) A source with 2 volts minimun output (higher the better) and impedance output lower than 100 Ohms (lower the better). You definitely need interconnects screened and with the lower possible capacitance and shorter possible lenght (Nordost Quattrofil are an ideal choice).You need ALL this requirements. If you failed in one of the requirements then it´s very possible you obtain an horrible sound. But if you have all the system "in tune" then I can assure you a good passive like my Audio Synthesis Passion Ultimate will beat ANY active preamp at ANY price (I´ve tried a demo at home with the Conrad Johnson ART versus my Audio Synthesis Ultimate, and the AS Ultimate wons every time)
Hope this helps.
I agree with Joseph. My transformer attenuators will beat any resistor or potentiometer-based volume controls. Using transformer attenuators also solves the problem of source impedence, since transformers are ratio devices and the power is preserved. i.e. the lower the voltage, the higher the current, and the lower the output impedence.
No ! It is not alway true. It only problem on Resistor attenuator or Normal V.R Pot. It don't have problem on Transformers tapped V.R.1. No need a High impedance input in Power amplifiers due to the turn ratio will higher the Input impedance from Passive Pre-amps. e.g turns Ratio 3:1 (When work at 1/3 Volumn) , Power amps input impedance at 10K. Input resistance seen by CD or other source will be . 10K x (3 x 3) = 90K ohm. So Use step down tapped transformers will increase to high impedance especially in low level. (Sometime down to 100:1 or more . So Even 10K Input impedance power amps will made it become 100M seen by your source.
2. No need a Low output impedance due to same reason as point 1.
3. Yes ! It really need a Higher output to drive your power amplifers to full power. It nay be at least 1V or Over is suitable but most CD/SACD have good enough voltage to drive it very good.
Some Mistake on test output Impedance of Transformers coupling Pre-amps : It can not test by Ohm meter.
Output Impedance is not Fix but domain by it turns ratio. MOre lower the Volumn. More higher input impedance on transformers passive pre-amps.
The about theory only suitable for step down type transformers Pot. Step up type will be reverse it.
Thanks for your input. I was talking just about conventional passive units (working with resistors, not transformers). With "conventional" passive preamps I am positivetely sure all the the requirements I said are true. BTW I´ve heard transformer based passive preamps are not so transparent or neutral sounding like "conventional" passive units due to the existence of a transformer in the signal path. Ultra high quality passive units uses the "less is more" approach in the signal path with ferocity. Of course the compatibility of the transformer based type units is the strong point.
No ! A good transformer coupling still can get transparent or neutral sounding as traditional Resistor type passive Pre-amps. It only some manufacturer made it too narrow in band width due to some technical reason. I had try many difference way to winding it . I finally has a very good result. You may be can found a Model Passive T1 in AA Review or in UHF Issue 62. I think it will change your mind in Transformers coupling. I will open it detail later Due to We are applicated patend in China to avoid copy. We have many completitor in China like to copy our products design now. e.g A transformers coupling Headphone amp.
It should work better with one than a solid state amp. I use a Creek OBH12 with a Croft Toubadour and it's a great combo.
Hi.I recommend a passive pre for use with my valve (tube) power amps, but this is based on experience. Whether a passive pre works does not depend on the topology of the power amp.
You need to look up the input sensitivity and input impedence specification of the amp. Idealy the input impeadence should be higher than 100K ohms and the sensitivity better than 500mV for full output and cable lengths should be kept short.
As with any piece of equipment, try before you buy.
Chris Jennings
Steve-I had problems with a Mod Squad passive linedrive and a Moscode600-due to an impedance mismatch.Raanan
P.S. All DPA's pres are active SS-none passive.
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