@vetusto, No need to apologize. Stupid would be not asking, when doing so would provide the answer.
OP = original poster: you.
OP = original poster: you.
Threshold T-200. Help me choose a preamplifier
Good day, Colleagues!
Not so long ago, at an auction in Japan, I accidentally won the Threshold T-200 amplifier. I really wanted this brand, but I was looking for the T-800D model. But it turned out to buy this amplifier ... And now I am very tormented with the choice.
I spent two days on the internet looking for balanced amplifiers. Here is a list, is there anything on this list worth seeing?
Pass Labs X1 -
This preamplifier is sold in Russia at a very good price, it seems to me. 1800 dollars. But I do not know his condition. The photographs show that the cable that connects the power supply and the preamplifier itself is frayed. And the power supply is not complete, but a small black box.
Pass Labs X2.5 - I found this preamp for 2000 euros in Croatia, but shipping will cost around 500 euros, so it is already very expensive for me.
Black Ice F-360 - A very interesting preamplifier. The ad suggests that this preamp has very high detail and can expand the scene. :) But I don't believe in advertisements.
Leema Acoustics Pyxis ll - This amplifier is quite expensive, I found it in my country for $ 2500 and this is a showcase sample. It has an impressive range of features, there is a phono stage, which I also need, and balanced inputs and outputs.
Electrocompaniet ec 4.7
Electrocompaniet EC 4.8
Krell KSL-2
Audia Flight Pre
Quad Artera Pre
Rotel RC-5000
Audio research LS-15
audio research LS-2B
Spectron Model 10
Audio research LS 17
BAT VK-30
McIntosh C2200 - But this is already very dear to me.
I really look forward to your help and advice in choosing.
97 responses Add your response
@vetuso. What I posted, is that the “balanced” output of the Pass would not be good with the “balanced” inputs of the Threshold. And, that the balanced circuitry was part of the expense of the Pass. As has been pointed, out while a pre with a suitably low balanced output impedance could work nicely, such beasts are rare. You might be better off finding a single ended only pre. While transistor output devices have become rather rugged for 50 years now, should your somewhat old Threshold’s somewhat unusual IGBT devices fail, you might have a Dickens of a time finding replacement parts. You might have to scrap the amp, or do a total rebuild with different transistors. As it is, if not already done so, the caps will be soon due for replacement. |
| Post removed |
Part of the expense that went into that Pass pre was for it's balanced circuitry, which won't be a good match into your Threshold amp.Did you say Pass Labs is not good for my Threshold? "which won't be a good" - can you say "not good"? Did I get it right? Did you say that because Threshold has a resistance of about 1 kΩ, and the output impedance at the Pass Labs balanced outputs is 0.35 kΩ? Did I understand everything correctly? That is, I need to look for a preamplifier with an output impedance of no more than 50 ohms on balanced outputs? A respected colleague in this topic wrote a little higher that the output impedance of the preamplifier should be 20 times lower than the input impedance of the amplifier. That is, if the input impedance of the amplifier is 926 ohms, then the output impedance of the preamplifier = 926/20 = 46 ohms. Fifty ohms is very little ... I hardly ever find such a preamplifier ... If I painted everything correctly, then a tragedy awaits me. What kind of preamp should I get? |
Part of the expense that went into that Pass pre was for it's balanced circuitry, which won't be a good match into your Threshold amp. Pass Laboratories Aleph X2.5 Stereo Preamplifier Rich, Warm, And Pleasant Review By John Gatski (enjoythemusic.com) Threshold T-200 power amplifier Measurements | Stereophile.com |
Before you begin compile any list you should ensure that every pre on it is capable of driving that input impedance to full effect. This will probably weed out 90% of the market for starters.I have already made my choice. I will be taking Pass Labs X2.5 or Pass Labs X1. Most likely the first one, because the second one costs much higher than my budget, and the seller does not want to give up in price, therefore, if I don’t persuade, then in 1-2 days I will buy Pass Labs X2.5 in Japan. |
Just for your information, Threshold T-200 (1994-98) was designed by Swedish engineer Michael Bladelius. At the time Michael was working in Threshold, the company underwent ownership changes and sold to Dynatech in 1988, and Nelson Pass left it in 1992. Mike Bladelius became the head of the design office at that time. Threshold T-200 specification: Output power: 100W into 8 ohms (20dBW), 200W into 4 ohms (20dBW), 350W into 2 ohms (19.4dBW). Full power bandwidth: DC–80kHz, +0/–3dB. Distortion: <0.1%; typically <0.02%. Voltage gain: 27.4dB balanced, 28dB unbalanced. Input sensitivity: 1.21V balanced, 1.13V unbalanced to produce 100W into 8 ohms. Input impedance: 50k ohms unbalanced, 2k ohms balanced. Current consumption: 2A, idle; up to 12A full output in mono. |
Be real careful with the T series. It was prone to melting down. I owned a T2 and the T400. Both had to go back to Threshold three times each for issues. One day I fired up my system (quite literally) and my Snell's burned up from DC current sent to them by the amp and preamp. I unloaded them when Threshold was still in business. Should anyone buy a T2 pre amp; DO NOT connect it to your system without FIRST connecting the power supply to the preamp!!! You will experience a system meltdown. |
vetusto ... the question is: what is the output impedance of Pass Labs X2.5?According to the manual, 360 balanced 150 unbalanced. |
For good voltage transfer from preamp to power amp it is better to have a low impedance at the output of the preamp and to have a high impedance at the input of the power amp. We should using a minimum ratio of >1:10 to improve transfer efficiency and I recommend >1:20 which transfers > 95% of the voltage. 100Ω : 2000Ω = 1: 20 2000 / (2000+100) = 95% If the ratio is low it will affected the system frequency response and noise floor. Also a preamp with high output impedance will has greatest possibility to hear differences in interconnect cables, a very low output impedance preamp will be immune to cable effects. |
For preamp choice, if you intend to use balanced inputs of the Threshold T-200, be caution of its 2kΩ input impedance!@imhififan, I do not completely understand what you are talking about. More precisely, I understand individual words, but I do not grasp the meaning in these numbers. If the preamp on the balanced outputs is greater than 100 ohms, what happens? In other words, I need to understand what the consequences will be if I choose the wrong preamp. |
@luxmancl38,
Thank you for the extended story. Probably, if I knew that this amplifier was not designed by Nelson Pass, then I probably would not hunt for it like that. :) But, already, what has been done is done.
|
The T-200 was designed by Michael Bladelius. He was originally hired by Nelson Pass. Michael also designed the Forte 4A a 50 wpc Class A amp. I had one years ago and always regretted selling it. Forte was the budget line of Threshold. The big difference between the T series and the earlier models are the output transistors. The T models and and the Forte's use Toshiba IGBT's. These transistors are no longer in production.The T-200 has 16 matched IGBT's per channel. It runs rather warm. I had a pair of Modified T-50's that I bought from a former Threshold employee. Michael Bladalius turned them into mono blocks w/24 matched IGBT's per amp. Michael Bladelius has his own company in his home country of Sweden. Also at Threshold during that time were Eric Lauchli, B.D. Dale and Lorin Peterson founders of Coda audio. |
Just to clarify, I don't build any preamplifiers that cost over $5K, I'm not sure where the $10K comes from....O! Good day, Aric, and good mood! I didn't mean to offend you, forgive me if this happened! I thought it was a company, I didn't expect it to be one person. :) I recently saw an Aric Audio preamplifier on ebay and it cost 11 thousand dollars. :) For some reason I can't find a link to this amplifier now. But if I meet, I will definitely post it here. :) |
I use Aric Audio preamps. The Unlimited in my secondary system,and The Motherlode II in my main system.Wow! These are very expensive preamps. I've met Aric Audio on ebay occasionally, they cost $ 10k. :) For me, this is absolutely not real money. :) Although, maybe I'm confusing something. I will put these preamplifiers in the search, I will follow them. |
Please tell us which tube preamps do you use?
The point is that I have always believed that it is best to use a tube preamplifier with a transistor amplifier. With it, the sound will be alive.
However, colleagues on other forums convince me that it is necessary to take exactly something from these preamplifiers, which I have given above.
All this is expensive, and I do not have the opportunity to first buy Pass Labs, and then buy, for example, Audio research tube. Therefore, you need to choose now.
|
All designed by Nelson Pass. I’ve heard great things about all of these. I’m sure someone with firsthand knowledge will be chiming in soon. I have two Nelson Pass amps,(First Watt F5,and J2) I run tube preamps with them. The results put a huge smile on my face. However that doesn’t give me experience with your choices. As long as the pre you choose is in proper working order, I would speculate great sound. |
For many days of choosing and searching for a preamplifier, I have compiled the following list:
Pass Labs x1
Pass Labs x2.5
Threshold T2
Threshold T3
These four preamps are in priority.
But I have not yet found an inexpensive device from the above-mentioned list. They all cost from 3 thousand dollars.
|
Yahoo auction. There is a "deferred bid" which is triggered 5 minutes before the end of trading. I followed this amp for 6 days and half an hour before the end of the auction, the price was still around $ 1100. I decided to place a bet.
And the service informed me that my rate is lower than the one that has already been offered. Apparently, someone made this deferred bet. I bet $ 1,200, but it was also below that deferred bet. Then I started wondering how much my appponent had bet ... :) I started raising my bet, 1300, 1400, 1500, 1800, 2000 dollars - your bet is accepted. :) I think this is a very high price for this amplifier. But no one else put more than $ 2000 ... So I became the owner of Threshold for $ 2300 (another $ 300 - delivery to Moscow). Something like this. :)
|
