Hello everyone,
Having realized my dream of designing and building a 3-Way, Coaxial Compression Driver, and Horn speaker capable of playing down to 300Hz by 112.5dB, paired with a Closed Bass 15” (101 dB), I now have the opportunity to take my hobby more seriously. Previously, I was building DIY speakers based on blueprints from the internet.
I recently acquired funds, allowing me to delve deeper into the world of amplifiers. Despite having zero knowledge about amps initially, I've gradually gained understanding. My preference is to drive these speakers with a tube amplifier. I have an DSP + Active Crossover + Preamp+DAC Allinone Solution from the German high-end horn manufacturer Hornsolution with a Nadja Board.
Through some coincidences, I obtained a pair of Quad II with original tubes, together with a DIYTube Preamp (1 Phono (mm), 4 Line 1 Tape In). My plan is to implement a passive crossover for the coaxial compression driver, enabling me to drive them with one tube amp. I intend to connect the amp to the Hornsolution Nadja, and have it only cut the frequencies below 300Hz, and use the Tube PreAmp for the CD Player/TT attached to the Nadja.
Now, my questions:
A) For the bass, which will receive a low pass filter for the crossover, I'm uncertain about the right amp. Should I go for a Tube or Class A or D with more wattage?
B ) I've attached a picture of the amp. Can you confirm if the amp is wired to 8 ohms? What's your initial impression of its condition?
C) The preamp was inherited, and the person doesn't know much about it. Can someone assess the quality/value of the preamp? Was it worth the 300€?
D) What are your overall thoughts on my plan? Does it make sense?
Thank you all, looking forward to your thoughts.
Having realized my dream of designing and building a 3-Way, Coaxial Compression Driver, and Horn speaker capable of playing down to 300Hz by 112.5dB, paired with a Closed Bass 15” (101 dB), I now have the opportunity to take my hobby more seriously. Previously, I was building DIY speakers based on blueprints from the internet.
I recently acquired funds, allowing me to delve deeper into the world of amplifiers. Despite having zero knowledge about amps initially, I've gradually gained understanding. My preference is to drive these speakers with a tube amplifier. I have an DSP + Active Crossover + Preamp+DAC Allinone Solution from the German high-end horn manufacturer Hornsolution with a Nadja Board.
Through some coincidences, I obtained a pair of Quad II with original tubes, together with a DIYTube Preamp (1 Phono (mm), 4 Line 1 Tape In). My plan is to implement a passive crossover for the coaxial compression driver, enabling me to drive them with one tube amp. I intend to connect the amp to the Hornsolution Nadja, and have it only cut the frequencies below 300Hz, and use the Tube PreAmp for the CD Player/TT attached to the Nadja.
Now, my questions:
A) For the bass, which will receive a low pass filter for the crossover, I'm uncertain about the right amp. Should I go for a Tube or Class A or D with more wattage?
B ) I've attached a picture of the amp. Can you confirm if the amp is wired to 8 ohms? What's your initial impression of its condition?
C) The preamp was inherited, and the person doesn't know much about it. Can someone assess the quality/value of the preamp? Was it worth the 300€?
D) What are your overall thoughts on my plan? Does it make sense?
Thank you all, looking forward to your thoughts.
It does make sense indeed. I am running a very similar setup, the two upper bands being a two way multiple entry horn. It is powered by a 300B SET amp. Below it, I have a 15" mid-bass. That one is powered by Denon PMA1500AE via the power amp input (bypassing its preamp). I would recommend a good quality ss amplifier - since you need more power due to the difference in sensitivities. Also, if you plan to boost the low end by DSP (I can recommend that), you will need extra headroom in the amplifier. I cannot comment on the other points.
Are those the original coupling caps? When (not if) they go leaky they put your OT at risk, and those OTs are not the easiest to come by.
Thank you, happy to hear. Out of curiosity how to you handle the crossover when your 300B are firing both ways
@ahankinson I’m out of town right now and will check a soon as I’m back but i think so. Good shout will look into replacing them. Can you see if its wired to 16 or 8 Ohm
I use first order series crossover, since it is a MEH and then MiniDSP 2x4 HD for crossover to the bass and general equalization (also for the MEH channel). I am waiting for my DCX464 to return - and I plan to implement a passive crossover for it as well. In a similar way - use a simple passive crossover and equalize by DSP.
This is the bit in the manual that says how to change the output impedance. I can’t see the letters in your photos so I can’t say for sure.
You need to read Keith Snooks site for proper care and feeding of these:
https://keith-snook.info/quad-ii-valve-power-amplifier.html
You need to read Keith Snooks site for proper care and feeding of these:
https://keith-snook.info/quad-ii-valve-power-amplifier.html
Attachments
Sorry, a few more comments:
- it’s funny that someone mucked about with the cathode capacitors. That looks a bit “how ya doin” (to quote EEVblog Dave).
- likewise the resistors are all changed but they left the 0.1 mfd cap. Maybe that’s still good but still weird to change all the resistors and leave that.
- your pic doesn’t include the can cap. Is that new or original? It can also fail.
- you should know that the input doesn’t have a dc blocking cap as that was part of the 22 preamp output circuit. So any DC on your preamp output will go straight into the driver on the II, throwing the bias off. So just double-check that your preamp has no DC on the output.