Hi,
Re: Uesugi U-BROS-1
Specifications for my preamplifier are not available anywhere, HiFi Engine has copy of brochures, no other data is available. I tried through the staff of Stereo Sound [Japan] but to no avail.
For example, I would like to find out what the phono loading values are. There are three phono inputs 1 and 2 are standard, input 3 is high level, I have no idea what the gain is. Please see photo.
Cheers,
Re: Uesugi U-BROS-1
Specifications for my preamplifier are not available anywhere, HiFi Engine has copy of brochures, no other data is available. I tried through the staff of Stereo Sound [Japan] but to no avail.
For example, I would like to find out what the phono loading values are. There are three phono inputs 1 and 2 are standard, input 3 is high level, I have no idea what the gain is. Please see photo.
Cheers,
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A relatively simple way to test loading resistance is to use an ohms meter for each input jack, pin to ground.
The "standard" must be 47K, there's no room for variation. Unless an input specifically states that is is for a MC (Moving Coil) cartridge, it's going to be 47K. MC would not be specified as "high level", it would be called "high gain" unless there's a serious language barrier at work.
Without having the schematic handy, I'd say there's a ciruitry change downstream for higher output cartridges.
In solid state preamps they usually change the first transistor's emitter bias resistor via a switch setting.
You best bet to eliminate further speculation would be to read and go over the Owner's Manual for an exact answer.
I'm certain that would clear up your curiosity.
Probably a voltage-divider *before* the preamp. This is bad form but if the input is overloading it is better than overload. There's several possible values but even with low-% standard parts it won't be 47k exact. (And does not have to be exact.)
You're in luck. Note the 100VAC AC line rating, as would be expected.
Still no input capacitance loading specified, but that was common back then.
Phono gain appears to be 40dB, and the line stage gain 22dB, also typical of the time.
Uesugi U-Bros-1: Manufacturer's technical parameters:
Input sensitivity / impedance (SP output at rated power):
PHONO 1 / 2 - (2mV / 47 kOhm)
PHONO 3 - (6.5 mV / 47 kΩ)
AUX 1 / 2, TAPE PB - (200 mV / 140 kΩ)
AUX 3 - (1000 mV / 120 kΩ)
Output level / impedance REC OUT (200 mV nominal, 40 V max):
PRE OUT (nominal 2.5 V, max. 30 V)
Supply voltage AC100V, 50Hz / 60Hz
Used lamps: 12AX7 x 5 / 12AU7 x 2
Dimensions: Main body: W532 x H146 x D360 mm
Power supply: W127 x H146 x D314 mm
Weight: Main body approx. 10.7 kg.
Power supply approx. 4.3 kg.
price 430,000 yen (1975-)
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Great info Rayma, thank you.
The PS transformer came wired for 100VAC but it also has a 117VAC tap, I resoldered it and got rid of the transformer. Some Luxman transformers have also this feature.
The PS transformer came wired for 100VAC but it also has a 117VAC tap, I resoldered it and got rid of the transformer. Some Luxman transformers have also this feature.
Now you need a schematic. Surely one of those Japanese audio sites will have it,
since they seem to have everything.
since they seem to have everything.
Odds are that seventh tube is a cathode follower output buffer for the line stage. Same specs otherwise.
Can someone tell me what the power consumption on the Uesugi U-Bros-1 preamp is? I am considering a purchase of this preamp (leaving as 100V), attaching two low power 100V model monoblock amplifiers to the switched outlets, and need to calculate the total power consumption (adding values for the two monoblocks and the preamp) in order to purchase the correctly-rated (W) Accupwr step-down power transformer to then connect the preamp to.
Also considering as alternative Luxman CL-36 Ultimate preamp which has 75W power consumption. In this case, I already have the correctly-rated Accupwr step-down transformer which is 300W rated.
Thank you, Don
Also considering as alternative Luxman CL-36 Ultimate preamp which has 75W power consumption. In this case, I already have the correctly-rated Accupwr step-down transformer which is 300W rated.
Thank you, Don